Ribs and sternum.

Home In its shape, the chest resembles an ovoid with an upper narrow end and a wider lower end, both ends being obliquely cut. In addition, ovoid chest

somewhat compressed from front to back. The chest, compages thoracis, has two openings or apertures: the upper, apertura throracis superior, and lower apertura thoracis inferior,

covered by a muscular septum - the diaphragm. The ribs limiting the lower aperture form the costal arch, arcus costalis. The leading edge of the lower aperture has a notch in the shape of an angle, angulus infrastemalis, substernal angle; at its apex lies the xiphoid process. The spinal column protrudes into the chest cavity along the midline, and on the sides of it, between it and the ribs, wide pulmonary grooves appear, sulci pulmonales, in which the posterior edges of the lungs are located. The spaces between the ribs are called intercostal spaces,

spatia intercostalia.

With the transition to upright walking, the chest becomes wider and shorter, but the ventro-dorsal size still prevails over the transverse (monkey form). Finally, in humans, in connection with the complete transition to upright walking, the hand is freed from the function of movement and becomes a grasping organ of labor, as a result of which the chest experiences the pull of the muscles of the upper limb attached to it; the insides press not on the ventral wall, which has now become the front, but on the lower one, formed by the diaphragm, as a result of which the line of gravity in a vertical position of the body is transferred closer to the spinal column. All this leads to the fact that the chest becomes flat and wide, so that the transverse dimension exceeds the anteroposterior (human shape; Fig. 24).

Reflecting this process of phylogenesis, the chest has different shapes in ontogenesis. As the child begins to stand up, walk and use his limbs, and as the entire apparatus of movement and internal organs grow and develop, the chest gradually acquires a characteristic human shape with a predominant transverse dimension.

The shape and size of the chest are also subject to significant individual variations, due to the degree of development of muscles and lungs, which in turn is associated with the lifestyle and profession of a given person. Since it contains vital organs such as the heart and lungs, these variations have great importance to assess the physical development of an individual and diagnose internal diseases. Usually there are three shapes of the chest: flat, cylindrical and conical. In people with well-developed muscles and lungs, the chest becomes wide, but short and takes on a conical shape, that is, its lower part is wider than the upper, the ribs are slightly inclined, the angulus infrasternalis is large. Such a chest is in a state of inhalation, which is why it is called inspiratory. On the contrary, in people with poorly developed muscles and lungs, the chest becomes narrow and long, acquiring a flat shape, in which the chest is strongly flattened in the anteroposterior diameter, so that its anterior wall is almost vertical, the ribs are strongly inclined, and the angulus infrasternalis is sharp. The chest is in a state of exhalation, which is why it is called expiratory. The cylindrical shape occupies an intermediate position between the two described. In women, the chest is shorter and narrower in the lower section than in men, and more rounded. Social factors on the shape of the chest are reflected in the fact that, for example, in some capitalist and developing countries, children of the exploited segments of the population living in dark houses, with a lack of nutrition and solar radiation, develop rickets (“English disease”), in which the chest takes on the shape of a “chicken breast”: the anteroposterior size predominates, and the sternum abnormally protrudes forward, like in chickens. In pre-revolutionary

In northern Russia, shoemakers who spent their whole lives sitting on a low stool in a bent position and using their chest as a support for the heel when driving nails into the sole, a depression appeared on the front wall of the chest, and it became sunken (funnel-shaped chest of shoemakers). In children with long and flat chests, due to poor muscle development, when sitting on a desk incorrectly, the chest appears to be in a collapsed state, which affects the activity of the heart and lungs. To avoid diseases, children need physical education.

Movements chest. Respiratory movements consist of alternately raising and lowering the ribs, along with which the sternum moves. During inhalation, the posterior ends of the ribs rotate around the axis mentioned in the description of the joints of the ribs, and their anterior ends are raised so that the chest expands in anteroposterior size. Due to the oblique direction of the axis of rotation, the ribs simultaneously move apart to the sides, as a result of which the transverse size of the chest also increases. When the ribs are raised, the angular bends of the cartilages are straightened, movements occur in the joints between them and the sternum, and then the cartilages themselves are stretched and twisted. At the end of the inhalation caused by the muscular act, the ribs lower, and then exhalation occurs.

SKELETON HEADS

Scull(cranium) only partly relates to the musculoskeletal system. It primarily serves as the seat of the brain and the sensory organs associated with the latter; in addition, it surrounds the initial part of the digestive and respiratory tracts, which open outward. Accordingly, the skull in all vertebrates is divided into two parts: the brain skull, neurocranium and visceral skull, cranium viscerale. IN of the brain skull there is a vault, calvaria, and the foundation basis.

The human brain skull includes: unpaired occipital, sphenoid, frontal and ethmoid bones and paired temporal and parietal bones. The visceral skull includes paired ones - the upper jaw, lower nasal concha, palatine, zygomatic, nasal, lacrimal bones and unpaired - vomer, lower jaw and hyoid bones.

Development of the skull. The skull, like the skeleton of the head, is determined in its development by the above-mentioned organs of animal and plant life.

The cranium develops in connection with the brain and sensory organs. Animals that do not have a brain do not have a skull. In chordates (lancelet), in which the brain is in its infancy, it is surrounded by a connective tissue membrane (membranous skull).

With the development of the brain in fish, a protective box is formed around the latter, which in cartilaginous fish (sharks) acquires cartilaginous tissue (cartilaginous skull), and in bony fish it acquires bone tissue (the beginning of the formation of a bony skull).

With the emergence of animals from water onto land (amphibians), cartilaginous tissue is further replaced by bone tissue, which is necessary for protection, support and movement in conditions of terrestrial existence.

In other classes of vertebrates, connective and cartilaginous tissues are almost completely replaced by bone tissue, and a bone skull is formed, which is more durable. The development of individual bones of the skull is also determined by the same factors. This explains the relatively simple structure

the structure of the bones of the cranial vault (for example, the parietal) and the very complex structure of the bones of the base, for example the temporal, which is involved in all functions of the skull and is a container for the organs of hearing and gravity. In terrestrial animals, the number of bones decreases, but their structure becomes more complicated, because a number of bones are the product of fusion of previously independent bone formations.

In mammals, the brain skull and visceral skull are closely fused with each other. In humans, due to the greatest development of the brain and sensory organs, the neurocranium reaches a significant size and predominates over the visceral skull.

The visceral skull develops from the material of paired gill arches enclosed in the lateral walls of the head section of the primary intestine. In lower vertebrates living in water, the gill arches lie meta-dimensionally between the gill slits through which water passes to the gills, which are aquatic respiratory organs.

The I and II branchial arches are divided into dorsal and ventral parts. The upper jaw (partially) develops from the dorsal part of the first arch, and the ventral part of the first arch takes part in the development lower jaw. Therefore, in the first arc a distinction is made between processus maxillaris and processus mandibularis.

As animals emerge from the water onto land, the lungs gradually develop, i.e., air-type respiratory organs, and the gills lose their importance. In this regard, gill pouches in terrestrial vertebrates and humans are present only in the embryonic period, and the material of the gill arches is used to build facial bones. Thus, the driving forces behind the evolution of the head skeleton are the transition from aquatic to terrestrial life (amphibians), adaptation to living conditions on land (other classes of vertebrates, especially mammals) and the highest development of the brain and its tools - the senses, as well as the appearance of speech (humans) ).

Reflecting this line of evolution, the human skull in ontogenesis goes through 3 stages of development: 1) connective tissue, 2) cartilaginous and 3) bone. The transition of the second stage to the third, i.e. the formation of secondary bones on the basis of cartilage, lasts throughout a person’s life. Even in an adult, remnants of cartilaginous tissue between the bones are preserved in the form of their cartilaginous joints (synchondroses). The cranial vault, which serves only to protect the brain, develops directly from the membranous skull, bypassing the cartilage stage. The transition of connective tissue into bone tissue also occurs throughout a person’s life. Remains of non-ossified connective tissue are preserved between the bones of the skull in the form of fontanelles in newborns and sutures in children and adults (see below). The brain skull, which is a continuation of the spinal column, develops from the sclerotomes of the cephalic somites, which are formed in 3-4 pairs in the occipital region around the anterior end of the chorda dorsalis.

The mesenchyme of sclerotomes, surrounding the brain vesicles and developing sensory organs, forms a cartilaginous capsule, cranium primordiale(initial), which, unlike the spinal column, remains unsegmented. The notochord penetrates the skull up to the pituitary gland, hypophysis, as a result of which the skull is divided in relation to the notochord into notochordal and prechordal parts. In the prechordal part in front of the pituitary gland, another pair of cartilages, or cranial crossbars, trabeculae cranii, are laid, which are in connection with the cartilaginous nasal capsule lying in front, enclosing the olfactory organ. On the sides of the notochord there are cartilaginous plates called parachordalia. Subsequently, trabeculae cranii fuse with parachordalia into one cartilaginous plate, and parachordalia - with cartilaginous auditory capsules, enclosing the rudiments of the hearing organ (Fig. 25). Between nasal and auditory

Rice. 25. Development of the skull (diagram).

/ - nasal capsule; 2 - visual capsule; 3 - auditory capsule; 4 - parachordal cartilage; 5 - chorda dorsalis; b - trabeculae cranii.

capsules on each side of the skull create a recess for the organ of vision.

Reflecting evolutionary fusion into larger formations, the bones of the skull base arise from separate bony formations (formerly independent) that fuse together to form mixed bones. This will be discussed when describing the individual bones of the base of the skull.

The cartilages of the gill arches are also transformed (Fig. 26, Table 2): the upper part (of the first gill or jaw arch) participates in the formation of the upper jaw. On the ventral cartilage of the same arch, the lower jaw is formed, which is attached to the temporal bone through the temporomandibular joint.

The remaining parts of the gill arch cartilage turn into auditory ossicles: hammer and anvil. The upper section of the second branchial arch (hyoid) goes to the formation of the third auditory ossicle - the stapes. All three auditory ossicles are not related to the bones of the face and are located in the tympanic cavity, which develops from the first gill pouch and makes up the middle ear (see “Organ of Hearing”). The rest of the hyoid arch goes to build the hyoid bone (lesser horns and partly the body) and the styloid processes of the temporal bone along with the lig. stylohyoideum.

The third branchial arch gives rise to the remaining body parts of the hyoid bone and its large horns. From the remaining gill arches come the cartilages of the larynx, which are not related to the skeleton.

Thus, in humans, the bones of the skull can be divided into 3 groups according to their development.

1. Bones forming the brain capsule:

a) developing on the basis of connective tissue - bones of the arch: parietal
ny, frontal, upper part of the squama of the occipital bone, squamosal and tympanic
part of the temporal bone;

b) developing on the basis of cartilage - bones of the base: wedge-shaped (behind
with the exception of the medial plate of the pterygoid process), the lower part
scales, basilar and lateral parts of the occipital bone, petrous part
temporal bone.

2. Bones developing in connection with the nasal capsule:

a) based on connective tissue - lacrimal, nasal, vomer;

b) based on cartilage - the ethmoid and inferior nasal concha.

3. Bones developing from the gill arches:

a) motionless - upper jaw, palatine bone, zygomatic bone;

Rice. 26. Scheme of the relationship between the derivatives of the gill arches. Cartilaginous and bone elements arising from the gill arches in humans: the lower jaw, the hyoid apparatus, some cartilages of the larynx and trachea.

Gill arches: 1 - first; 2 - third; 3 - fourth; 4 - fifth; 5 - second.

b) movable - the lower jaw, hyoid bone and auditory ossicles.

The bones developed from the brain capsule make up the brain skull, and the bones of the other two sections, with the exception of the ethmoid, form the bones of the face.

Due to the strong development of the brain, the cranial vault, which rises above the rest of the skull, is very convex and rounded in humans. This feature sharply distinguishes the human skull from the skulls of not only lower mammals, but also great apes, a clear proof of which can be the capacity of the cranial cavity. Its volume in humans is about 1500 cm 3, in apes it reaches only 400-500 cm 3. The fossil ape-man (Pithecanthropus) has a skull capacity of about 900 cm 3 .

Table 1

Derivatives of the branchial arches and their corresponding nerves(Braus)

Visceral (gill in the broad sense) arches

Derivatives of human visceral arches

Cranial nerves

First branchial arch Second branchial arch

Third branchial arch Fourth branchial arch Fifth branchial arch

Hammer, incus, ventral cartilage of the mandible

Stirrup, styloid process of the temporal bone, lesser horns and part of the body of the hyoid bone, ligamentum stylohyoideum

Large horns and part of the body of the hyoid bone

Thyroid and other cartilages of the larynx

Third branch of the trigeminal nerve (V)

Facial nerve (VII)

Glossopharyngeal nerve (IX)

Superior laryngeal branch of the vagus nerve (X)

Inferior laryngeal branch of the vagus nerve (X)

SKULL BONES

Occipital bone

Occipital bone, os occipitdle, forms the posterior and lower walls of the cranium, participating simultaneously in both the cranial vault and its base. Accordingly, it (being a mixed bone) ossifies both as a covering bone on the basis of connective tissue (the upper part of the occipital scales), as well as on the basis of cartilage (the remaining parts of the bone). In humans, it is the result of the fusion of several bones that exist independently in some animals. Therefore, it consists of 4 separately laid parts that grow together into a single bone only at the age of 3 - 6 years. These parts, closing the foramen magnum, foramen magnum(place of transition spinal cord into the oblong from the spinal canal into the cranial cavity), the following: in front - the basilar part, pars basilaris, on the sides - lateral parts, partes laterales, and behind - occipital scales, squama occipitalis. The upper part of the scales, wedged between the parietal bones, ossifies separately and often remains separated for life by a transverse suture, which is also a reflection of the existence in some animals of an independent interparietal bone, os interparietale, as it is called in humans.

occipital scales, squama occipitalis as the covering bone has the appearance of a plate, convex on the outside and concave on the inside. Its external relief is due to the attachment of muscles and ligaments. Thus, in the center of the outer surface there is the external occipital protrusion, protuberantia occipitalis externa(place of appearance of the ossification point). From the protrusion, a curved line runs laterally on each side - the upper one is a different line, linea nuchae superior. A little higher there is a less noticeable one - Npea nhchae supr"ema(highest). From the occipital protuberance down to the posterior edge of the foramen magnum, the external nuchal crest runs along the midline, crista occipitalis externa. From the middle of the ridge, other lower lines go to the sides, lineae nuchae inferibres. The relief of the internal surface is determined by the shape of the brain and the attachment of its membranes, as a result of which this surface is divided by two ridges intersecting at right angles into four pits; both of these ridges together form a cruciform elevation, eminentia cruci-fbrmis, and at the place of their intersection - the internal occipital protrusion, protuberantia occipitalis int"erna. The lower half of the longitudinal ridge is sharper and is called crista occipitalis int"erna, the upper and both halves (usually the right) of the transverse are equipped with well-defined grooves: sagittal, and transverse sulcus sinus transversi(traces of adjacency of the venous sinuses of the same name).

Each of the lateral parts, partes laterales, participates in the connection of the skull with the spinal column, therefore it bears the occipital condyle on its lower surface, condylus occipitalis - place of articulation with the atlas.

Approximately near the middle of the condylus occipitalis, the hypoglossal canal canalis hypoglossalis passes through the bone.

On the upper surface of the pars lateralis there is the sulcus sinus sigmoidei (a trace of the so-called venous sinus).

basilar part, pars basilaris, by age 18, fuses with the sphenoid bone, forming a single bone in the center of the base of the skull os basilare.

On the upper surface of this bone there is a slope, clivus, fused from two parts, on which the medulla oblongata and the pons lie. The pharyngeal tubercle protrudes on the lower surface, tub"erculum pharyngeum, to which the fibrous membrane of the pharynx is attached.

Sphenoid bone

Sphenoid bone, os sphenoiddle, unpaired, resembles a flying insect, which explains the name of its parts (wings, pterygoid processes).

The sphenoid bone is the product of the fusion of several bones that independently exist in animals, therefore it develops as a mixed bone from several paired and unpaired ossification points, forming 3 parts at the time of birth, which in turn fuse into a single bone by the end of the first year of life. It distinguishes the following parts: 1) body, corpus(in animals - unpaired basisphenoid and presphenoid); 2) big wings, alae majores(in animals - paired alisphenoid); 3) small wings, alae minores(in animals - paired orbitosphenoid); 4) pterygoid processes, processus pterygoidei(its medial plate is a former paired pterygoid, develops on the basis of connective tissue, while all other parts of the bone arise on the basis of cartilage).

Body, corpus on its upper surface it has a depression in the midline - the sella turcica, sella tur"cica, at the bottom of which lies a fossa for the pituitary gland, fossa hypophysidlis. There is a hill in front of her, tuberculum sellae, which runs transversely sulcus chiasmatis for chiasma of the optic nerves; optic canals are visible at the ends of the sulcus chiasmatis, candles optici, through which the optic nerves pass from the orbital cavity to the cranial cavity. At the back, the sella turcica is limited by the bony plate, the dorsum of the saddle, d"orsum sellae. A curved carotid groove runs on the lateral surface of the body, sulcus caroticus, trace of the internal carotid artery.

On the anterior surface of the body, which is part of the posterior wall of the nasal cavity, a ridge is visible, crista sphenoidalis, below, entering between the wings of the opener. The crista sphenoidalis connects anteriorly to the perpendicular plate of the ethmoid bone. Irregularly shaped holes are visible on the sides of the ridge, aperturae sinus sphenoidalis, leading to the airway/sinus, sinus sphenoidalis, which is located in the body of the sphenoid bone and is separated by a septum, septum sinuum sphenoiddlium, into two halves. Through these openings the sinus communicates with the nasal cavity.

In a newborn, the sinus is of very small size and only around the 7th year of life begins to grow rapidly.

Small wings, alae minores, are two flat triangular plates, which with two roots extend forward and lateral from the anterosuperior the edges body of the sphenoid bone; between the roots of the small wings there are the mentioned visual channels, candles optici. Between the lesser and greater wings is the superior orbital fissure, fissura orbitlis superior, leading from the cranial cavity to the orbital cavity.

Big wings, alae majores, extend from the lateral surfaces of the body laterally and upward. Near the body, posterior to the fissura orbitalis superior, there is a round opening e, foramen rotundum, leading anteriorly into the pterygopalatine fossa, caused by the passage of the second branch trigeminal nerve, n. trigemini. Posteriorly, a large wing in the form of an acute angle protrudes between the scales and the pyramid of the temporal bone. Near it there is a spinous aperture. foramen spinosum, through which a passes. meningea media.

Anterior to it is a much larger oval foramen, foramen ovale, through which passes the third branch of n. trigemini.

Large wings have four surfaces: the medulla, fades cerebral-lis, ocular, fades orbitalis, temporal, fades temporalis, and maxillary fades maxilldris. The names of the surfaces indicate the areas of the skull where they face. The temporal surface is divided into the temporal and pterygoid parts by the infratemporal crest, crista infriitemporalis.

Pterygoid processes, processus pterygoidei extend vertically downward from the junction of the large wings with the body of the sphenoid bone. Their base is pierced by a sagittal canal, canalis pterygoideus, - the place of passage of the homonymous nerve and vessels. The anterior opening of the canal opens into the pterygopalatine fossa.

Each process consists of two plates - lamina medialis And lamina lateralis, between which a hole forms at the back, fossa ptery-goidea.

The medial plate at the bottom is bent with a hook, hamulus pterygoideus, through which the tendon of the m starting on this plate is thrown. tensor veli palatini (one of the muscles of the soft palate).

Temporal bone

Temporal bone, os temporale, the paired bone has a complex structure, as it performs all 3 functions of the skeleton and not only forms part of the side wall and base of the skull, but also contains the organs of hearing and gravity. It is the product of the fusion of several bones (mixed bone), which independently exist in some animals, and therefore consists of three parts: 1) the scaly part, pars squamosa; 2) drum part, pars tympanica and 3) rocky part, pars petrosa.

During the 1st year of life, they merge into a single bone, closing the external auditory canal, meatus acusticus externus, in such a way that the scaly part lies above it, the stony part medially from it, and the tympanic part behind, below and in front. Traces of the fusion of individual parts of the temporal bone are preserved for life in the form of intermediate sutures and fissures, namely: at the border of pars squamosa and pars petrosa, on the anterosuperior surface of the latter - fissura petrosquambsa; in the depths of the mandibular fossa - fissura tympanosquambsa, which is divided by a process of the petrous part into fissura petrosquamosa And fissura petrotympanica(the chorda tympani nerve exits through it).

scaly part, pars squamosa, participates in the formation of the lateral walls of the skull. It belongs to the integumentary bones, i.e. it ossifies on the basis of connective tissue and has a relatively simple structure in the form of a vertical plate with a rounded edge overlapping the corresponding edge of the parietal bone, margo squamosa, in the form of fish scales, which is where its name comes from.

On its brain surface, fades cerebrdlis, visible traces of the brain, finger indentations, impressibnes digitatae, and a groove ascending upward from a. meningea media. The outer surface of the scales is smooth, participates in the formation of the temporal fossa and is therefore called fades temporalis. The zygomatic process departs from it, processus zygomdticus, which goes forward to connect with zygomatic bone. At its origin, the zygomatic process has two roots: anterior and posterior, between which there is a fossa for articulation with the lower jaw, fossa mandibularis. On the bottom surface

an articular tubercle is placed on the anterior root, tuberculum articuldre, preventing the head of the lower jaw from dislocating forward when the mouth opens significantly.

drum part, pars tympanica The temporal bone forms the anterior, lower and part of the posterior edge of the external auditory canal, ossifies endesmally and, like all integumentary bones, has the appearance of a plate, only sharply curved.

External auditory canal, medtus acusticus externus, It is a short canal that goes inward and somewhat forward and leads into the tympanic cavity. The upper edge of its outer opening, poms acusticus externus, and part of the posterior edge is formed by the scales of the temporal bone, and along the remaining length by the tympanic part.

In a newborn, the external auditory canal is not yet formed, since the tympanic part is an incomplete ring (annulus tympanicus), covered by the eardrum. Due to such a close position of the eardrum outwards, diseases of the tympanic cavity are more often observed in newborns and young children.

rocky part, pars petrosa, so named for the strength of its bone substance, due to the fact that this part of the bone is involved in the base of the skull, and is the bony receptacle for the organs of hearing and gravity, which have a very thin structure and require strong protection from damage. It develops on the basis of cartilage. The second title of this part is pyramid, given by its shape as a triangular pyramid, the base of which faces outward, and the apex faces forward and inward toward the sphenoid bone.

The pyramid has three surfaces: front, back and bottom. The anterior surface is part of the bottom of the middle cranial fossa; the posterior surface faces posteriorly and medially and forms part of the anterior wall of the posterior cranial fossa; the lower surface faces down and is visible only on the outer surface of the base of the skull. The external relief of the pyramid is complex and is determined by its structure as a container for the middle (tympanic cavity) and inner ear(bone labyrinth, consisting of the cochlea and semicircular canals), as well as the passage of nerves and blood vessels. On the front surface of the pyramid, near its apex, a slight depression is noticeable, impressio trigemini, from the trigeminal nerve ganglion (p. trigemini,). Two thin grooves run outward from it, the medial one - siilcus n. petrbsi majoris, and lateral - siilcus n. petrosi minoris. They lead to two homogeneous foramina: medial, hiatus candlis n. petrosi majoris, and lateral hiatus candlis n. petrbsi minoris. Outside of these holes, an arched elevation is noticeable, eminentia arcudta, formed due to the protrusion of a rapidly developing labyrinth, in particular the superior semicircular canal. The surface of the bone between eminentia arcuata and squama temporalis forms the roof of the tympanic cavity, tegmen tympani.

Approximately in the middle of the posterior surface of the pyramid is the internal auditory opening, pbrus acusticus internus, which leads to the internal auditory canal, meatus acusticus internus, where the facial and auditory nerves pass, as well as the artery and veins of the labyrinth.

A thin pointed styloid process extends from the lower surface of the pyramid, facing the base of the skull, proces-sus styloideus, serving as a place of attachment for the muscles of the “anatomical bouquet” (mm. styloglossus, stylohyoideus, stylopharyngeus), as well as ligaments - ligg. stylohy-oideum and stylomandibulare. The styloid process represents a part of the temporal bone of branchial origin. Together with lig. stylohyoideum it is a remnant of the hyoid arch.

Between the styloid and mastoid processes there is a stylomastoid foramen, foramen stylomastoideum, through which the n. facialis exits and a small artery enters. Medial to the styloid process there is a deep jugular fossa, fossa juguldris. Anterior to the fossa jugulafis, separated from it by a sharp ridge, is the external opening sleepy channel, foramen caroticum externum.

The pyramid has three edges: anterior, posterior and upper. The short anterior margin forms an acute angle with the scales. In this corner the opening of the myotubal canal is noticeable, canalis musculotubdrius, leading into the tympanic cavity. This channel is divided by a partition into two sections: upper and lower. Upper, smaller, half-channel, semicandlis m. tensoris tympani, contains this muscle, and the lower, larger one, semicandlis tubae auditivae, is the bony part of the auditory tube, which serves to conduct air from the pharynx into the tympanic cavity.

A clearly visible groove runs along the upper edge of the pyramid, separating the front and back surfaces, sulcus sinus petrosi superi-oris,- trace of the venous sinus of the same name.

The posterior edge of the pyramid anterior to the fossa jugularis connects with the basilar part of the occipital bone and, together with this bone, forms the sulcus sinus petrosi inferioris - a trace of the inferior petrosal venous sinus.

The outer surface of the base of the pyramid serves as a place for muscle attachment, which determines its external relief (process, notches, roughness). Downwards it extends into the mastoid process, processus mastoideus. The sternocleidomastoid muscle is attached to it, which maintains the head in the balance necessary for an upright position of the body. Therefore, the mastoid process is absent in quadrupeds and even apes and develops only in humans in connection with their upright posture. On the medial side mastoid process there is a deep mastoid notch, incisura mastoidea,- place of attachment of m. digastricus; even more inward - a small furrow, sulcus a. occipitalis,- trace of the artery of the same name.

On the outer surface of the base of the mastoid process, a smooth triangle is distinguished, which is a place for rapid access to the cells of the mastoid process when they are filled with pus.

Inside the mastoid process contains these cells cellulae mastoideae, which are air cavities separated by bone bars that receive air from the tympanic cavity, with which they communicate through the antrum mastoideum. There is a deep groove on the cerebral surface of the base of the pyramid, sulcus sinus sigmoidei, where the venous sinus of the same name lies.

Canals of the temporal bone. The largest channel is canalis caroticus, through which the internal carotid artery passes. Beginning with its external opening on the lower surface of the pyramid, it rises upward, then bends at a right angle and opens with its internal opening at the apex of the pyramid medial to the canalis musculotubarius. Facial canal (Fig. 27), canalis facialis, begins in the depths of the porus acusticus internus, from where the canal first goes forward and laterally to the cracks (hiatus) on the anterior surface of the pyramid; at these holes, the canal, remaining horizontal, turns at a right angle laterally and backwards, forming a bend - the elbow, geniculum canalis facialis, and then down and ends through foramen stylomastoideum, located on the lower surface of the pyramid of the temporal bone. Canalis muculotubarius(see above).

Rice. 27. Temporal bone (os temporale), right; vertical cut parallel to the axis of the pyramid.

/ - cavUm tympani; 2 - tegmen tympani; 3 - canalis facialis; 4 - canalis caroticus (internal opening); 5 - impressio trigemini; b - semicanalis tubae auditivae; 7 - canalis caroticus (external opening); 8 - fossa jugularis; 9 - canalis facialis et for. stylomastoideum; 10 - cellulae mastoideae.

Parietal bone

Parietal bone, os parietale, steam room, forms the middle part of the cranial vault. In humans, it reaches the greatest development in comparison with all animals due to the highest development of his brain. It represents a typical integumentary bone, performing primarily a protective function. Therefore, it has a relatively simple structure in the form of a quadrangular plate, convex on the outside and concave on the inside. Its four edges serve to connect with neighboring bones, namely: the anterior - with the frontal, margo frontalis, posterior - with the occipital, margo occipitalis, medial - with the sonominal bone of the other side, margo sagittalis, and lateral - with the scales of the temporal bone, margo squamosus. The first three edges are serrated, and the last is adapted to form a scaly suture. Of the four corners, the anteromedial one connects to the frontal bone, angulus frontalis, ne-mediolateral with sphenoid bone, angulus sphenoidalis, posteromedial with the occipital bone, angulus occipitalis, and posterolateral with the base of the mastoid process of the temporal bone, angulus mastoideus. The relief of the outer convex surface is caused by the attachment of muscles and fascia. In its center protrudes the parietal tubercle, tuber parietale(place of beginning of ossification). Below it are curved temporal lines - lineae temporales(superior et inferior) - for the temporal fascia and muscle. Near the medial edge there is a hole, foramen parietale(for artery and vein). Relief of the internal concave surface, fades int"erna, due to the fit of the brain and especially its hard shell; the places of attachment of the latter to the bone look like a groove running along the medial edge of the sagittal sinus, sulcus sinus sagittalis superibris(trace of the venous sinus, sinus sagittalis superior), as well as in the area of ​​the angulus mastoideus transverse groove,

sulcus sinus sigmoidei(trace of the venous sinus of the same name). The vessels of this shell seem to be imprinted in the form of branching grooves on almost the entire inner surface. On the sides of the sulcus sinus sagittalis superioris traces of so-called arachnoid granulations are visible, foveolae granulares.

Frontal bone

Frontal bone, osfrontdle, unpaired, participates in the formation of the cranial vault and belongs to its integumentary bones, developing on the basis of connective tissue. In addition, it is associated with the senses (smell and vision). According to this dual function, it consists of two sections: vertical - scales, squama frontal is, and horizontal. The latter, in relation to the organs of vision and smell, is divided into a paired orbital part, pars orbitalis, and unpaired nasal, pars nasalis. IN As a result, the frontal bone is divided into 4 parts:

1. Frontal scales, squama frontalis, like any integumentary bone, it has the appearance of a plate, convex on the outside and concave on the inside. It ossifies from two ossification points, visible even in an adult on the outer surface, fades externa, in the form of two frontal tubercles, tubera frontlia. These bumps are expressed only in humans due to brain development. They are absent not only in apes, but even in extinct forms of humans. The lower edge of the scales is called the supraorbital, mdrgo supraorbi-talis. Approximately on the border between the inner and middle third of this edge there is a supraorbital notch incisura supraorbitdlis(sometimes turns into foramen supraorbitale), the place of passage of the arteries and nerve of the same name. Immediately above the supraorbital margin, elevations that vary greatly in size and extent are noticeable - the brow ridges, arcus superciliares, which pass medially along the midline into a more or less erect platform, glabella(glabella). It is a reference point when comparing skulls modern man with a fossil. The outer end of the supraorbital margin extends into the zygomatic process, processus zygomdticus, connecting to the zygomatic bone. From this process a clearly visible temporal line goes upward, linea temporalis, which limits the temporal surface of the scales, fades temporalis. On the inner surface, fades interna, a groove runs along the midline from the posterior edge, sulcus sinus sagittalis superioris, which below passes into the frontal ridge crista frontalis. These formations are the attachment of the dura mater. Near the midline, pits of granulation of the arachnoid membrane (outgrowths of the arachnoid membrane of the brain) are noticeable.

2 and 3. Orbital parts, partes orbitales, They represent two horizontally located plates, which with their lower concave surface face the orbit, the upper one faces the cranial cavity, and their posterior edge connects to the sphenoid bone. On the upper cerebral surface there are traces of the brain - impressiones digitatae. Bottom surface fades orbitalis, forms the upper wall of the orbit and bears traces of the attachment of auxiliary devices of the eye; at the zygomatic process there is a fossa of the lacrimal gland, fossa gldndulae lacrimalis, near incisura supraorbitalis - fovea trochledris and a small thorn spina trochledris, where the cartilaginous block (trochlea) for the tendon of one of the eye muscles is attached. Both orbital parts are separated from each other by a notch, incisura ethmoidalis, filled with ethmoid bone on the entire skull.

4. Bow part, pars nasalis, occupies the anterior part of the ethmoidal notch along the midline; a comb is visible here, which ends in a sharp process - spina nasalis, taking part in the formation of nasal

howling septum. On the sides of the scallop there are pits that serve as the upper wall for the cells of the ethmoid bone; in front of them there is a hole leading into the frontal sinus, sinus frontalis,- a cavity that is located in the thickness of the bone behind the brow ridges and the size of which varies greatly. The frontal sinus, containing air, is usually divided by a septum septum sinuum frontalium. In some cases, additional frontal sinuses are found behind or between the main ones. The frontal bone in its shape is the most characteristic of all the bones of the skull for humans. In the most ancient hominids (like apes), it was sharply tilted back, forming a sloping, “running back” forehead. Behind the orbital narrowing it is sharply divided into scales and orbital parts. Along the edge of the eye sockets, from one zygomatic process to the other, there was a continuous thick ridge. In modern humans, the ridge has sharply decreased, so that only the brow ridges remain. According to the development of the brain, the scales straightened and took a vertical position, at the same time the frontal tubercles developed, as a result of which the forehead became convex from sloping, giving the skull a characteristic appearance.

Rice. 28. Ethmoid bone (os ethmoidale); back view.

/, 2 - crista galli; 3 - lam. cribrosa; 4 - lam. orbitalis;

5 - concha nasalis superior;

6 - lam. perpendicularis; 7 -
labyrinthus ethmoidalis.

Ethmoid bone

Ethmoid bone, os ethmoidale, unpaired, usually described among the bones of the brain skull, although for the most part it is involved in the formation of the face. Located centrally between the bones of the face, it comes into contact with most of them, participating in the formation of the nasal cavity and eye sockets, and is covered by them on the entire skull. It develops in connection with the nasal capsule, based on cartilage, and is built from thin bone plates surrounding the air cavities (Fig. 28). The bony plates of the ethmoid bone are arranged in the shape of the letter “T”, in which the vertical line is formed by a perpendicular plate, lamina perpendicularis, and the horizontal one is the cribriform plate, lamina cribrosa. Lattice labyrinths hang from the latter on the sides of the lamina perpendicularis, labyrinthi ethmoidales. As a result, the ethmoid bone can be divided into 4 parts:

1. Lamina cribrosa- rectangular plate performing incisura
ethmoidalis of the frontal bone. It is permeated like a sieve with small holes.
(hence its name), through which the branches of the olfactory
nerve (about 30). Along its midline rises the cock's head
Ben, crista galli(place of attachment of the dura mater of the brain).

2. Lamina perpendicularis is part of the nasal septum.

3 and 4. Labyrinthi ethmoidales represent a paired complex of bony air cells, cellulae ethmoidales, covered externally by a thin orbital plate, lamina orbitalis, forming the medial wall of the orbit (Fig. 29). The upper edge of the orbital plate connects with the orbital part of the frontal bone, anteriorly - with the lacrimal ossicle, posteriorly - with the sphenoid and orbital process of the palatine, below - with the upper jaw; all these bones cover the marginal cellulae ethmoidales. On the medial side of the labyrinths

4 Human anatomy

Rice. 29. Ethmoid bone (os ethmoi-dale); left view.

1 - crista galli; 2 - lam., orbifalis; 3 - cellulae eth-moidales posteriores; 4 - concha nasalis media; 5-lam. perpendicularis; 6 - cellulae ethmoidales anterio-res.

there are two nasal conchas - cbchae nasales superior et media, sometimes there is a third - concha nasalis supre"ma.

The conchae are curved bony plates, due to which the surface of the nasal mucosa covering them increases.

FACE BONES

Bones of the face, ossa faciei, form bone containers for the sense organs (vision, smell), as well as for the initial sections of the digestive (oral cavity) and respiratory (nasal cavity) systems, which determines their structure. At the same time, they were affected by those changes in the soft parts of the head that are caused by the process of humanization of the monkey, i.e. the leading role of labor, the partial transfer of grasping function from the jaws to the hands, which became organs of labor, the development of articulate speech, the development of the brain and its tools - sensory organs, and finally, the consumption of artificially prepared food, which facilitates the work of the masticatory apparatus.

Upper jaw

Upper jaw, maxilla, a paired bone with a complex structure due to its diverse functions: participation in the formation of cavities for the sensory organs - the eye socket and nose, in the formation of the septum between the cavities of the nose and mouth, as well as participation in the functioning of the masticatory apparatus.

The transfer of the grasping function from the jaws (as in animals) to the hands in humans due to their work activity has led to a decrease in the size of the upper jaw; At the same time, the appearance of speech in humans made the structure of the jaw more delicate. All this determines the structure of the upper jaw, which develops on the basis of connective tissue.

The upper jaw consists of a body and four processes.

A. The body, corpus maxillae, contains a large air sinus, sinus maxillaris(maxillary or maxillary, hence the name for sinus inflammation - sinusitis), which has a wide opening, hiatus maxillaris, opens into the nasal cavity. There are four surfaces on the body.

Front surface fades anterior, in modern humans, due to the weakening of the chewing function caused by artificial preparation of food, it is concave, and in Neanderthals it was flat. Below it passes into the alveolar process, where a number of elevations are noticeable, juga alveoldria, which correspond to the position of the tooth roots. The elevation corresponding to the canine is more pronounced than others. Above it and laterally there is a canine fossa, fossa canina. At the top, the anterior surface of the maxilla is delimited from the orbital by the infraorbital margin, margo infraorbitalis. Immediately below it the infraorbital foramen is noticeable, foramen infraorbitdle, through which the nerve and artery of the same name exit the orbit. The medial border of the anterior surface is the nasal notch, incisura nasalis.

infratemporal surface, fades infratempordlis, separated from the anterior surface by the zygomatic process and bears the tubercle of the maxilla, tuber maxillae, And sulcus palatinus major.

nasal surface, fades nasalis, below it passes into the upper surface of the palatine process. It has a visible ridge for the inferior turbinate. (crista conchdlis). A tear groove is visible behind the frontal process, sulcus lacrimalis, which, with the lacrimal ossicle and inferior concha, turns into the nasolacrimal canal - canalis nasolacrimalis, connecting the orbit with the inferior nasal meatus. Even more posteriorly there is a large opening leading to the sinus maxillaris.

Smooth, flat orbital surface, fades orbitalis, has a triangular shape. On its medial edge, behind the frontal process, there is a lacrimal notch, incisura lacrimalis, where the lacrimal ossicle enters. Near the posterior edge of the orbital surface, the infraorbital groove begins, sulcus infraorbitalis, which anteriorly turns into canalis infraorbitalis, opening to the above-mentioned foramen infraorbitale on the anterior surface of the upper jaw. The alveolar canals extend from the infraorbital canal, candles alveoldres, for nerves and vessels going to the front teeth.

B. Processes. 1. Frontal process, processus frontalis, rises upward and connects with the pars nasalis of the frontal bone. There is a ridge on the medial surface, Christa Ethmoiddlis - trace of the attachment of the middle turbinate.

2. Alveolar process, processus alveolaris, on your bottom
edge, drcus alveolaris, has dental cells, alveoli dentdles, eight top
their teeth; cells are separated by partitions, septa interalveolaria.

3. Palatine process, processus palatinus forms most of
hard palate, palatum osseum, connecting with the paired process opposite
reverse side with a median seam. Along the middle seam on the top,
the side of the process facing the nasal cavity goes nasal crest,
crista nasalis, connecting to the lower edge of the opener. Near the front end
crista nasalis, on the upper surface there is a noticeable hole leading into the incisive
channel, canalis incisivus. The upper surface is smooth, while the lower surface is turned
into the oral cavity, rough (impressions of the glands of the mucous membrane) and carries
longitudinal grooves, sulci palatini, for nerves and blood vessels. In the anterior section
the incisal suture is often visible, sutura incisiva. He separates the merged
with the upper jaw the incisive bone, os incisivum, which in many animals
occurs in the form of a separate bone (os intermaxillare), but in humans only as
rare option.

4. Zygomatic process, processus zygomaticus, connects to the cheekbone
howls with bone and forms a thick support through which it is transmitted to
zygomatic bone pressure when chewing.

Rice. 30. Palatine bone (os palatinum), right; outside view (A) and from the inside (b).

1 - processus sphenoidalis; 2 - incisura sphenopalatina; 3 - processus orbitalis; 4 - lam. perpendicularis; 5 - sul. palatinus major; 6 - processus pyramidalis; 7 - lam. horizontalis.

Palatine bone

Palatine bone, os palatinum, steam room; participates in the formation of a number of cavities of the skull - the nasal cavity, mouth, orbits and pterygopalatine fossa. This participation determines its unique structure in the form of a thin bone, consisting of two plates connected to each other at right angles and complementing the upper jaw (Fig. 30).

1. Horizontal plate, lamina horizontalis, complements
behind the processus palatinus maxillae, forming solid sky, palatum osseum.
On the lower surface of the horizontal plate of the palatine bone there is
greater palatine foramen, foramen palatinum majus, through koto
from the canalis palatinus major (see below) emerge the palatine vessels and
nerves.

2. Perpendicular plate, lamina perpendicularis, adjoining
goes to fades nasalis maxillae. There is a groove on its lateral surface,
sulcus palatinus major, which, together with the conominal groove of the maxilla
forms canalis palatinus major. Two visible on the medial surface
crest for two nasal conchas: middle (crista ethmoidalis) and inferior
(crista conchalis). The palatine bone has three processes: one, processus
pyramidalis, extends from the junction of the horizontal and perpendicular
no plates back and laterally and on the whole skull fills the notch
pterygoid process of the sphenoid bone. Through it vertically through
naltsy, canales minbres, nerves and blood vessels pass through. The other two perform
on the upper edge of the perpendicular plate, forming a notch between themselves,
incisura sphenopalatina, which, when connected to the body of the sphenoid bone
closes the hole, foramen sphenopalatinum (for the named vessels and
nerves). The anterior of these processes complements the floor of the orbit in the very
the back corner of it and that’s why it’s called processus orbitalis, and the back one is adjacent
to the lower surface of the body of the sphenoid bone and is called processus
sphenoidalis.

Rice. 31. Lacrimal bone (os lacrimale), left; outside view. 1 - sul. lacrimalis; 2 - crista lacrimalis posterior.

Rice. 32. Vomer.

/ - lam. perpendicularis ethmoid bone; 2 - margo superior vomer; 3 - margo posterior vomer.

Inferior turbinate

Inferior nasal concha, concha nasalis inferior, steam room; it is an independent bone, in contrast to the superior and middle shells, which are components of the ethmoid bone. With its upper edge it is attached to the side wall of the nasal cavity and separates the middle nasal passage from the lower one. The lower edge is free, and the upper edge is connected to the crista conchalis of the upper jaw and palatine bone.

Nasal bone

Nasal bone, os nasdle, adjacent to its mate, it forms the back of the nose at its root. In humans, compared to animals, it is underdeveloped.

Lacrimal bone

Lacrimal bone, os lacrimale(Fig. 31), steam room; it is a thin plate that is part of the medial wall of the orbit immediately behind the processus frontalis of the upper jaw. On its lateral surface there is a lacrimal crest crista lacrimalis posterior. Anterior to the crest there is a tear groove, sulcus lacrimalis, which, together with the groove on the frontal process of the upper jaw, forms the fossa of the lacrimal sac, fossa sacci lacrimalis. The human lacrimal bone is similar to that of apes, which serves as one of the proofs of their close relationship with hominids.

Opener, vomer(Fig. 32), unpaired bone; it is an irregularly quadrangular plate, reminiscent of a corresponding agricultural tool and part of the bony septum of the nose.

Its posterior edge is free and represents the posterior edge of the bony nasal septum, separating the posterior openings of the nasal cavity - choanae, through which nasal cavity communicates with the nasal part of the pharynx.

Cheekbone

Zygomatic bone, os zygomdticum, steam room, the strongest of the facial bones; it is an important architectural part of the face, closing the zygomatic processes of the frontal, temporal and maxillary bones and thereby helping to strengthen the facial bones in relation to the skull. It also provides a large surface for the beginning of the masticatory muscle. According to the location of the bone, three surfaces and two processes are distinguished. Side surface, fades lateralis, has the appearance of a four-pointed star and slightly protrudes in the form of a mound. The posterior, smooth, faces the temporal fossa and is called fades temporalis; third surface, orbital, fades orbitalis, participates in the formation of the walls of the orbit. The superior process of the bone, processus frontalis, connects with the zygomatic process of the frontal and the greater wing of the sphenoid bone. Lateral process processus temporalis, connecting with the zygomatic process of the temporal bone, it forms the zygomatic arch - the origin of the masticatory muscle.

Lower jaw

Lower jaw, mandibula, is a movable bone of the skull. It has a horseshoe shape due to its function (most important part of the masticatory apparatus), and by development from the first branchial (mandibular) arch, the shape of which it retains to a certain extent. In many mammals, including lower primates, the lower jaw is a paired bone. In accordance with this, in humans it is formed from two rudiments, which, gradually growing, merge in the 2nd year after birth into an unpaired bone, retaining, however, along the midline a trace of fusion of both halves (symphysis mentalis). According to the structure of the masticatory apparatus from the passive part, i.e., the teeth that perform the chewing function, and the active part, i.e., the muscles, the lower jaw is divided into a horizontal part, or body, corpus mandibulae bearing teeth, and a vertical one in the form of two branches, rami mandibulae, serving for the formation of the temporomandibular joint and the attachment of the masticatory muscles. Both of these parts - horizontal and vertical - converge at an angle, angulus mandibulae, to which the masticatory muscle is attached on the outer surface, causing the appearance of the so-called tuberosity, tubero-sitasmasseterica. On the inner surface of the angle there is a pterygoid tuberosity, tuberositaspterygoidea, place of attachment of another masticatory muscle, m. pterygoideus medialis. Therefore, the activity of the masticatory apparatus affects the size of this angle. In newborns it is close to 150°, in adults it decreases to 130-110°, and in old age, with the loss of teeth and weakening of the act of chewing, it increases again. Also when comparing monkeys with various types hominids, corresponding to the weakening of the chewing function, a gradual increase in the angulus mandibulae is observed from 90° in apes to 95° in Heidelberg man, 100° in Neanderthal man and 130° in modern man (Fig. 33) 1 .

1 Brief anthropological information is given from the textbooks of M. A. Gremyatsky and V. V. Ginzburg.

Rice. 33. Lower jaw.

/-newborn; 2 - men 30 years old; 3 - men 80 years old; 4 - the jaw of a modern man (red outline), combined with the jaw of a Heidelberg man. Its decrease is visible with the formation of the chin and coronoid process.

The structure and relief of the body of the lower jaw are determined by the presence of teeth and its participation in the formation of the mouth.

So, upper body, pars alveoldris, bears teeth, as a result of which on its edge, arms alveolaris, there are dental alveoli, alveoli dentales, with partitions, septa interalveolaria, corresponding to the external alveolar elevations, jiiga alveoldria. The rounded lower edge of the body is massive, forms the base of the body of the lower jaw, basis mandibulae. In old age, when teeth fall out, the pars alveolaris atrophies and the whole body becomes thin and low. Along the midline of the body, the crest of the symphysis passes into mental eminence triangular shape, protuberantia mentalis, the presence of which characterizes modern man. Of all mammals, the chin is expressed only in humans, and even then modern ones. In apes, Pithecanthropus and Heidelberg man, there is no chin protrusion and the jaw in this place has a backward-curving edge. In Neanderthals, the mental protuberance is also absent, but the corresponding edge of the lower jaw looks like right angle. Only modern man has a real chin. On the sides of this elevation the mental tubercles are visible, tubercula mentd-On, one on each side. On the lateral surface of the body, at the level of the space between the 1st and 2nd small molars, there is a mental foramen, foramen mentality, representing the exit of the mandibular canal, canalis mandibulae, serving for the passage of nerves and blood vessels. An oblique line stretches back and upward from the tuberculum mentale area, linea obliqua. Two mental spines protrude on the inner surface of the symphysis, spinae mentdles, - places of tendon attachment mm. genioglossi. In anthropomorphic monkeys this muscle

it is attached not by a tendon, but by a fleshy part, as a result of which a fossa is formed instead of a spine. In the series of fossil jaws there are all transitional forms - from the pit characteristic of monkeys, caused by the fleshy attachment of m. genioglossus and combined with the absence of a chin, until the development of a spine caused by the tendon attachment of the genioglossus muscle and combined with a protruding chin. Thus, changing the method of attachment of m. genioglossus from fleshy to tendon entailed the formation of spina mentalis and, accordingly, the chin. Considering that the tendinous method of attachment of the tongue muscles contributed to the development of articulate speech, the transformation of the bone relief of the lower jaw in the chin area should also be associated with speech and is a purely human characteristic. On the sides of the spina mentalis, closer to the lower edge of the jaw, the attachment points of the digastric muscle, fossae digastricae, are noticeable. Further posteriorly, the maxillary-hyoid line goes back and upward towards the branch, linea mylohyoidea, - place of attachment of the muscle of the same name.

jaw branch, ramus mandibulae, extends upward on each side from the posterior part of the body of the lower jaw. The opening of the lower jaw is noticeable on its inner surface, foramen mandibulae, leading into the canalis mandibulae mentioned above. The inner edge of the hole protrudes in the form of a tongue of the lower jaw, lingula mandibulae, where lig is attached. sphenomandibulare; The lingula is more developed in humans than in monkeys. Posterior to the lingula, the mylohyoid groove begins and goes down and forward. sulcus mylohyoideus(trace of nerve and blood vessels). At the top, the branch of the lower jaw ends in two processes: the anterior one, the coronoid, proce"ssus coronoideus(formed under the influence of strong traction temporal muscle), and the posterior condyle, processus condylaris, participates in the articulation of the lower jaw with the temporal bone. A notch is formed between both processes incisura mandibulae. Towards the coronoid process, the crest of the buccal muscle rises on the inner surface of the branch from the surface of the alveoli of the last large molars, Christa buccinatoria.

The cleft process has a head, cdput mandibulae, and neck, cbllum mandibulae; There is a hole in the front of the neck, fovea ptery-goidea(place of attachment of m. pterygoideus lateralis).

To summarize the description of the lower jaw, it should be noted that its shape and structure characterize modern humans. Described on p. 87 factors led to a decline in dental activity and reduction of the lower jaw. Along with this, a person began to develop articulate speech, associated with the strengthened and delicate work of the tongue muscles attached to the lower jaw. Therefore, the mental region of the lower jaw, associated with these muscles, functioned intensively and resisted the action of regression factors, and mental spines and a protrusion appeared on it. The formation of the latter was also facilitated by the expansion of the jaw arch, associated with an increase in the transverse dimensions of the skull under the influence of the growing brain. Thus, the shape and structure of the human lower jaw were influenced by the development of labor, articulate speech and the brain that characterize a person.

Hyoid bone

The chest (compages thoracis) is an osteochondral formation consisting of 12 thoracic vertebrae, 12 pairs of ribs and sternum, connected to each other by joints, synchondroses and ligaments. The rib cage is the skeleton of the walls of the chest cavity, which contains the heart and large vessels, lungs, esophagus and other organs.

The chest is flattened in the anteroposterior direction and has the appearance of an irregular cone. It has 4 walls (anterior, posterior, lateral and medial) and 2 openings - upper and lower. The anterior wall is formed by the sternum, costal cartilages, back wall- the thoracic vertebrae and the posterior ends of the ribs, and the lateral vertebrae - the ribs. Ribs separated from each other intercostal spaces(spatia intercostalia). Top hole chest(apertura thoracis superior) is limited by the first thoracic vertebra, the inner edges of the first ribs and the upper edge of the manubrium of the sternum. The anteroposterior size of the upper aperture is 5-6 cm, the transverse size is 10-12 cm. Inferior thoracic outlet(apertura thoracis inferior) is bounded behind by the body of the XII thoracic vertebra, in front by the xiphoid process of the sternum, and on the sides by the lower ribs. The median anteroposterior size of the inferior aperture is 13-15 cm, the largest transverse is 25-28 cm. The anterolateral edge of the inferior aperture, formed by the connections of the VII-X ribs, is called costal arch(arcus costalis). The right and left costal arches anteriorly limit substernalcorner(angulus infrasternalis), open downwards. The apex of the infrasternal angle is occupied by the xiphoid process of the sternum.

The shape of the chest depends on many factors, especially body type. In people brachymorphic type physique, the chest is conical in shape. Its upper part is significantly narrower than the lower part, the substernal angle is obtuse. The ribs are slightly inclined forward, the difference between the transverse and anteroposterior dimensions is small.

At dolichomorphic type body type, the chest has a flattened shape. Its anteroposterior size is significantly inferior to the transverse one, the ribs are strongly inclined anteriorly and downward, and the substernal angle is acute.

For people mesomorphic type The body type is characterized by a cylindrical chest. In shape it occupies an intermediate position between conical and flattened.

Women's chests are usually more rounded and shorter than men's. In newborns, the anteroposterior size of the chest prevails over the transverse size. In old age, the chest flattens and becomes longer. This is due to an age-related decrease in muscle tone and lowering of the anterior ends of the ribs.

6. The structure of the sternum and ribs, their connections.

Sternumconsists of three parts: body, manubrium and xiphoid process, which with age (30-35 years) fuse into a single bone.

At the junction of the body of the sternum with the manubrium there is an anteriorly directed angle of the sternum.

The manubrium of the sternum has two paired notches on its lateral surfaces (for articulation with the two upper pairs of ribs) and one paired notch on the upper part (for connection with the clavicles). The body of the sternum also has notches on the sides , to which the cartilaginous parts of the II-VII pairs of ribs are attached. The xiphoid process can vary in size and shape, most often triangular, forked at the end, and often has a hole in the center.

Edge(costae) It is a long, flat, spongy bone that bends in two planes. In addition to the bone itself, each rib also has a cartilaginous part. The bone part, in turn, includes three sections: the body, the head with the articular surface on it and separating them

neck of the rib.

At the junction of the neck of the rib with the body there is a tubercle of the rib, which has an articular surface through which the rib articulates with the transverse process of the corresponding thoracic vertebra.

The body of the rib, represented by spongy bone, has different lengths: from the first pair of ribs to the seventh pair of ribs, the length of the body gradually increases, and at the following ribs the body is successively shortened. A longitudinal groove runs along the lower inner edge; in which intercostal nerves and vessels lie.

In its shape, the chest resembles an ovoid with an upper narrow end and a wider lower end, both ends being obliquely cut. In addition, the ovoid of the chest is somewhat compressed from front to back.

Rib cage, compages thoracis , has two holes or apertures: top, apertura throracis superior , And lower, apertura thoracis inferior , covered by a muscular septum - the diaphragm. The ribs limiting the lower aperture form costal arch, arcus costalis.

The leading edge of the lower aperture has a notch in angle shape, angulus infrastemalis , substernal angle; at its apex lies the xiphoid process. The spinal column protrudes into the chest cavity along the midline, and on the sides of it, between it and the ribs, wide pulmonary grooves, sulci pulmonales, in which the posterior edges of the lungs are located. The spaces between the edges are called intercostal spaces, spatia intercostalia .

In mammals, in which, due to their horizontal position, the thoracic viscera exert pressure on the lower wall, the chest is long and narrow, and the ventro-dorsal size exceeds the transverse one, as a result of which the chest has a sort of laterally compressed shape with a protruding ventral wall in the form keel (keel-shaped).

In monkeys, due to the division of the limbs into arms and legs and the beginning of the transition to upright posture, the chest becomes wider and shorter, but the ventro-dorsal size still prevails over transverse (monkey shape).

Finally, in humans, in connection with the complete transition to upright walking, the hand is freed from the function of movement and becomes a grasping organ of labor, as a result of which the chest experiences the pull of the muscles of the upper limb attached to it; the insides press not on the ventral wall, which has now become the front, but on the lower one, formed by the diaphragm, as a result of which the line of gravity in a vertical position of the body is transferred closer to the spinal column. All this leads to the fact that the chest becomes flat and wide, so that the transverse dimension exceeds the anteroposterior ( human form; rice. 24).

Reflecting this process of phylogenesis, and in ontogenesis the chest has different shapes. As the child begins to stand up, walk and use his limbs, and as the entire apparatus of movement and internal organs grow and develop, the chest gradually acquires a characteristic human shape with a predominant transverse dimension.

Shape and size of the chest are also subject to significant individual variations due to the degree of development of muscles and lungs, which in turn is associated with the lifestyle and profession of a given person. Since it contains vital organs such as the heart and lungs, these variations are of great importance for assessing the physical development of an individual and diagnosing internal diseases.
There are usually three forms of the chest: flat, cylindrical and conical.

In people with well-developed muscles and lungs, the chest becomes wide, but short and takes on a conical shape, that is, its lower part is wider than the upper, the ribs are slightly inclined, angulus infrasternalis large. Such a chest is in a state of inhalation, which is why it is called inspiratory. On the contrary, in people with poorly developed muscles and lungs, the chest becomes narrow and long, acquiring a flat shape, in which the chest is strongly flattened in the anteroposterior diameter, so that its anterior wall is almost vertical, the ribs are strongly inclined, and the angulus infrasternalis is sharp.

The chest is in a state of exhalation, which is why it is called expiratory. The cylindrical shape occupies an intermediate position between the two described. In women, the chest is shorter and narrower in the lower section than in men, and more rounded. Social factors on the shape of the chest are reflected in the fact that, for example, in some capitalist and developing countries, children of the exploited segments of the population living in dark houses, with a lack of nutrition and solar radiation, develop rickets (“English disease”), in which the chest takes on the shape of a “chicken breast”: the anteroposterior size predominates, and the sternum abnormally protrudes forward, like in chickens.

IN pre-revolutionary Russia shoemakers who spent their entire lives sitting on a low stool in a bent position and using their chest as a support for the heel when driving nails into the sole, a depression appeared on the front wall of the chest and it became sunken (funnel-shaped chest of shoemakers). In children with long and flat chests, due to poor muscle development, when sitting on a desk incorrectly, the chest appears to be in a collapsed state, which affects the activity of the heart and lungs. To avoid diseases, children need physical education.

Movements of the chest. Respiratory movements consist of alternately raising and lowering the ribs, along with which the sternum moves. During inhalation, the posterior ends of the ribs rotate around the axis mentioned in the description of the joints of the ribs, and their anterior ends are raised so that the chest expands in anteroposterior size. Due to the oblique direction of the axis of rotation, the ribs simultaneously move apart to the sides, as a result of which the transverse size of the chest also increases. When the ribs are raised, the angular bends of the cartilages are straightened, movements occur in the joints between them and the sternum, and then the cartilages themselves are stretched and twisted. At the end of the inhalation caused by the muscular act, the ribs lower, and then exhalation occurs.

Educational video of chest x-ray anatomy

Other video lessons on this topic are:

The shape of the chest resembles a vegetable with a narrow upper end and a wider lower end, both ends being cut obliquely. Rib cage ( compagesthoracis) has 2 aperture holes: upper ( aperturethoracissuperior) lower ( apertura thoracis inferior) tightened by the muscular septum of the diaphragm. The ribs limit the lower aperture and form the costal dogma ( arcuscostales). The chest consists of: the thoracic spinal column, ribs (12 pairs), sternum. There are front and rear side walls. The anterior wall is shorter than the other walls, formed by the sternum and cartilage of the ribs. The posterior wall is longer than the anterior one and is formed by the thoracic vertebrae and sections of the ribs from the heads to the corners. There are pulmonary grooves ( sulcipulmonales), in which the back parts of the leshgki are placed. The space between the ribs is intercostal ( spatia intercostale) The lateral walls are longer than the front and back, formed by the bodies of the ribs and are more or less convex. Shape of the chest different people different (flat, cylindrical, conical). The chest of men is longer and wider and more cone-shaped than that of women. The shape of the chest also depends on age.

Connections between the clavicle and the scapula and sternum.

Sternoclavicular joint (art. Sternoclavicularis) is formed by the clavicular notch of the sternum and the sternal end of the clavicle. The joint is simple. The articular surfaces are covered with connective tissue cartilage, often saddle-shaped. Their discrepancy is equalized by the articular disc. The articular capsule is strong and attached to the edges of the articular surfaces of the bone. Through the disc, the joint cavity is divided into two non-communicating parts. The ligaments of the sternoclavicular joint include ligaments: 1) Anterior, posterior sternoclavicular ( ligg. Sternoklavikulareanteriusetposterius) strengthen the articular capsule in front, above, behind. 2) costoclavicular ( lig. Costoclavulare) comes from the upper edge of the first rib of the clavicle. 3) Interclavicular ligament ( lig. Interaclaviculare) stretched between the sternal ends of the clavicle.

AC joint(art. Acromioclavicularis) is formed by the articular surface of the humeral end of the clavicle and the articular surface of the acromion of the scapula. The joint is simple art. Simplecs the articular surfaces are flat. The joint cavity is divided into two parts by the articular disc. Multi-axle but with a sharply limited range of motion artt. Planae. Strengthening ligaments: 1) acromioclavicular ( lig. Aromioclavicularis) between the acromial end of the clavicle and the acromion of the scapula. 2) coracoclavicular ( lig. Coracoclaviculare) connects the acromial end of the clavicle and the acromial end of the scapula. 3) the conical ligament (lig. Conoideum) is stretched between the cone-shaped tubercle of the acromial end of the clavicle and the coracoid process of the scapula. Ligaments of the scapula: lig. Carocoacromiale – stretches from the anterior edge of the acromion to the procussus carocoideus 2) lig. Transversum scapule superius stretches over the notch of the scapula. 3) lig. The tranversum scapule inferius runs from the base of the acromion 2/3 of the neck of the scapula to the posterior edge of the cavity.

Shoulder joint: formation, ligaments, movements. (art.)

Humeri Formed by the glenoid cavity of the scapula ( cavitas glenoidalis scapulae ) and the head of the humerus (caput hume ri ) articular surfaces with geoline cartilage and do not correspond to each other: the congruence of the articular surfaces increases due to the articular labrum ( labium glenoidale ligg. ). The articular capsule is fixed on the scapula along the edge of the articular cartilage of the glenoid cavity and along the outer edge of the articular labrum; on the humerus it is attached along the anatomical neck. On the inner surface of the joint capsule there are triarticular brachial ligaments (). They are attached on one side by the rope of the neck of the humerus and on the other to the articular lip of the scapula. In addition, the shoulder joint has a powerful coracobrachial ligament ( lig. Coracohumerale) it goes from the outer edge of the coracoid process to greater tubercle humerus. Coracoacromial ligament ( lig. Coracoacromiale) goes above the shoulder joint together with the acromion and the coracoid process of the scapula to form. The shoulder joint is triaxial, spherical in shape ( art. Spheroidea) (circunduction) movement along all sides is frontal, sagittal, vertical, there are also circular movements. around the frontal axis of flexion-flexion, around the sagittal - abduction-ghost, around vertical rotation.

Elbow joint: formations, ligaments, movements. (art.

Cubiti) IN elbow joint art. 3 bones articulate: humerus, ulna, radius. The articulating bones form 3 joints enclosed in one capsule. The elbow joint is formed by the articular surface of the distal epiphysis of the humerus - its trochlea and the head of the condyle, the articular surfaces on the ulna - the trochlear and radial notches of the ulna, as well as the head and articular circumference of the radius. The joint is complex ( Composita ). The elbow joint is capable of flexion and extension, pronation and supination. The articular surfaces are covered with geoline cartilage. In the cavity of the elbow joint there are 3 joints: 1) Shoulder-ulnar ( art. Humeroulnaris ) - a trochlear joint with a helical structure of the articular surfaces. The articular surface on the shoulder side is a block ( trohlea ); the recess located on it is not perpendicular to the axis of the block, but at a certain angle to it - a helical stroke is obtained. Articulates with the block incisura trohlearis ulna. Single-axle ( ginglymus ) 2) brachioradial ( art. Humerоradialis art. ) Formed by the head of the condyle of the humerus and the articular fossa on the head of the radius, belongs to the spherical (caput hum Spheroidea art. ), movement occurs around 2 axes: frontal and vertical. 3) Proximal radioulnar (Radioulnaris proximalis

) lies between the radial apex of the ulna and the articular circumference of the head of the radius. The joint is cylindrical.

Synchondroses are present: between the first ribs and the sternum, the manubrium and the body of the sternum, the xiphoid process and the body of the sternum, the false ribs between each other with the formation of the costal arch, the bony parts of the ribs and the costal cartilages. The xiphoid process and costal cartilages usually do not ossify throughout life. Synostosis is observed between the manubrium and the body of the sternum in people over 40-50 years old. The costovertebral joints are described above. The sternocostal joints between the cartilages of the II-VII ribs and the costal notches of the sternum are flat in shape. Thanks to the elastic costal cartilages, costovertebral and sternocostal joints, and respiratory muscles, the chest is well adapted for breathing movements: during inhalation it rises and expands, and during exhalation it falls and narrows.

The rib cage as a whole is an irregular cone with a truncated apex. It has four walls - front, back, two sides and two openings - upper and lower apertures. The anterior wall is formed by the sternum and costal cartilages, the posterior wall by the thoracic vertebrae and posterior ends of the ribs, and the side walls by the ribs. The ribs are separated by intercostal spaces (intercostal spaces). The upper aperture is limited by the first thoracic vertebra, the inner edges of the first ribs and the upper edge of the manubrium of the sternum. The esophagus, trachea, vessels, and nerves pass through it into the chest cavity. The lower aperture is limited by the XII thoracic vertebra, the lower ribs and the xiphoid process of the sternum. It is closed by a diaphragm, through the holes of which abdominal cavity the aorta, esophagus, vessels and nerves descend.

The shape of the chest depends on body type, age, gender, and profession. In anatomy, there are two extreme forms - narrow, long, corresponding to the asthenic body type, and wide, short, corresponding to the hypersthenic type. Most people have an intermediate (normosthenic) chest shape. In newborns and young children, the lower thoracic opening is expanded due to the large liver. The anteroposterior size of their chest is larger than the transverse size. In old people, the chest becomes flatter and longer due to decreased muscle tone and lowering of the anterior ends of the ribs. In women, the relief of the chest is influenced by the mammary glands, in men - by the contours of the muscles of the shoulder girdle, chest, back, and abdominal muscles.

Pathological changes in the shape of the chest occur with curvatures of the spinal column (scoliosis, kyphosis), rickets, diseases of the chest organs (emphysema, heart defects). Observed congenital deformities, for example, funnel chest or “shoemaker's chest”. The keeled (“chicken”) shape of the chest is usually of rachitic origin. These deformations are manifested by a corresponding decrease or increase in the anteroposterior size of the chest. A barrel-shaped chest is characteristic of patients with pulmonary emphysema.