PRESENTATION ON PHYSIOLOGY ON THE TOPIC: “SPINAL CORD”. Completed by: Student 205 A group Avakyan A. A. Supervisor: Pomazan I. A.
Structure spinal cord The spinal cord is located inside the spinal column. It starts from the brain and looks like a white cord with a diameter of about 1 cm. On the anterior and posterior sides, the spinal cord has deep anterior and posterior longitudinal grooves. They divide it into right and left parts. On cross section a narrow central canal can be seen running the entire length of the spinal cord. It's full cerebrospinal fluid.
The structure of the spinal cord The spinal cord consists of white matter, located at the edges, and gray matter, located in the center and shaped like butterfly wings. Gray matter contains bodies nerve cells, and in white - their processes. Motor neurons are located in the anterior horns of the gray matter of the spinal cord (in the front wings of the “butterfly”), and in hind horns and around the central canal - interneurons.
Structure of the spinal cord The spinal cord consists of 31 segments. A pair of spinal nerves depart from each segment, starting with two roots - anterior and posterior. Motor fibers pass through the anterior roots, and sensory fibers enter the spinal cord through the dorsal roots and end on interneurons and motor neurons. In the posterior roots there is spinal ganglia, in which clusters of sensory neuron bodies are located.
Structure of the spinal cord 1. Anterior root 2. Spinal nerve 3. Spinal ganglion 4. Posterior root 5. Posterior sulcus 6. Spinal canal 7. White matter 8. Posterior horns 9. Lateral horns 10. Anterior horns 11. Anterior sulcus
Functions of the spinal cord The spinal cord performs two main functions: reflex and conduction. Reflex function lies in the fact that the spinal cord ensures the implementation of contraction of skeletal muscles, such as simple reflexes, such as extension and flexion of limbs, withdrawal of the hand, knee reflex, as well as more complex reflexes, which, in addition, are controlled by the brain.
FUNCTIONS OF THE SPINAL CORD Reflex Gray matter Conductive White matter Conducting motor impulses sensitive to the muscles of the body through impulses from the skin, descending conductive tendons, joints, pain and temperature receptor pathways Carries out voluntary movements Along the ascending pathways, connection between the brain and spinal cord
Functions of the spinal cord From the segments of the cervical and upper thoracic parts of the spinal cord, nerves extend to the muscles of the head, upper limbs, organs of the chest cavity, to the heart and lungs. The remaining segments of the thoracic and lumbar parts control the muscles of the body and organs abdominal cavity, and the lower lumbar and sacral segments of the spinal cord control the muscles lower limbs and lower abdominal cavity.
Nerve impulses from receptors in the skin, muscles and internal organs are carried through the white matter of the spinal cord to the brain, and impulses from the brain are sent to the executive neurons of the spinal cord. This is the conductive function of the spinal cord.
Spinal cord injury Complete injury: There is complete loss of sensation and muscle function below the level of injury. Partial Damage: Body functions below the level of damage are partially preserved. In most cases of spinal cord injury, both sides of the body are equally affected. Damage to the upper cervical regions spinal cord injury can cause paralysis of both arms and both legs. If the spinal cord injury occurs in the lower back, it can cause paralysis in both legs.
Conducting tracts of the spinal cord Ascending tracts Thin fasciculus (Gaull) Sphenoid fasciculus (Burdach), passes into rear pillars, impulses enter the cortex Conscious impulses from the musculoskeletal system spinocerebellar Dorsal horns Impulses from proprioceptors of muscles, tendons, ligaments; unconscious impulse spinothalamic Lateral and anterior pain and temperature sensitivity, tactile (touch, pressure)
Descending tracts corticospinal (pyramidal) Lateral and anterior Impulses from the cortex to skeletal muscles.
Sensory conduction (Gaull and Burdach pathways) spinocerebellar pathways (Flexig and Gowers pathways) pyramidal pathways Extrapyramidal pathways.
The doctrine of reflexes Jiří Prochazka (1749-1820) was the first to extend the concept of reflex to all activities nervous system, and not just its lower departments. He believed that a living organism selectively reacts to external influences, evaluating them in relation to the needs of the body: “External impressions arising in the sensory nerves very quickly spread along their entire length to the very beginning. There they are reflected according to a certain law, go to certain and corresponding motor nerves and along them they are extremely quickly directed to the muscles, through which they produce precise and strictly limited movements.”
Classification of reflexes 1) by biological significance: a) vital (nutritional, defensive, homeostatic, saving energy, etc.) b) zoosocial (sexual, child and parental, territorial, gregarious) c) self-development (research, play, freedom, imitative); 2) depending on the type of receptors stimulated: exteroceptive, interoceptive, proprioceptive; 3) according to the nature of the response: 1 - motor or motor (to muscles), 2 - secretory (to glands), 3 - vasomotor (to vessels).
Reflex - the body's reaction to changes in external or internal environment, carried out with the participation of the central nervous system (R. Descartes). Monosynaptic Polysynaptic afferent Interneuron efferent According to modern concepts, reflexes are “loop” because the result of the action affects the receptor that triggers this reflex (functional systems).
Examples of reflex arcs Monosynaptic, as a result of a sharp stretching of the proprioceptors of the quadriceps muscle, the lower leg is extended. But: even the simplest reflexes do not work separately. (Here: interaction with the inhibitory circuit of the antagonist muscle)
Examples of reflex arcs Defensive reflex Polysynaptic Irritation of skin receptors leads to coordinated activation of interneurons of one or different segments of the spinal cord
Examples of reflex arcs Reciprocal inhibition of antagonist muscles § is mutual (conjugate) inhibition of the centers of antagonistic reflexes, ensuring the coordination of these reflexes. The phenomenon is functional, i.e. muscles are not always antagonistic
Examples of reflex arcs 4 - disinhibition 4 1 3 2 A. continuous excitation of the motor centers of the central nervous system is divided into alternating acts of excitation of the right and left legs. (reciprocal + reciprocal inhibition) B. control of movement using the postural reflex (reciprocal inhibition)
Examples of reflex arcs Muscle receptors: 1. muscle spindles (intrafusal fibers) Gamma loop (motor control) 2. Golgi tendon complexes
Conditioned reflexes– combination of an indifferent (unconditioned) reflex with a conditioned stimulus (I.P. Pavlov) Essence: An indifferent stimulus (S) causes an orienting reflex (activation of a large number nerve centers). If at the same time (or a little later) the salivation reflex (unconditioned-B) is activated, a temporary connection will be formed (association) U B B U
The spinal cord (medulla spinalis), located in the spinal canal, is divided into two halves. On its lateral surfaces, the posterior (afferent) roots of the spinal nerves symmetrically enter and exit the anterior (efferent) roots. The section of the spinal cord corresponding to each pair of roots is called a segment. Within the spinal cord, the segments are cervical (I - VIII), thoracic (I - XII), lumbar (I - V), sacral (I - V) and coccygeal (I-III). The length of the spinal cord is on average 45 cm in men and 41 -42 cm in women, weight is 34 -38 g.
Cervical (intumescentia cervicalis) and lumbar (lumbosacral) (intumescenta lumbosacralis) - which correspond to the origin of fibers innervating the upper and lower extremities. In these sections of the spinal cord there is a greater number of nerve cells and fibers than in other sections.
In the lower parts of the spinal cord gradually narrows and forms the medullary cone (conus medularis).
- a - brain and spinal cord from the lateral surface;
- b - section of the spine with the spinal cord inside;
- c - spinal cord from the ventral surface.
- 1 - medulla oblongata (myelencephalon);
- 2 - intersection of pyramids (decussatio pyramidum);
- 3 - cervical thickening (intumescentia cervicalis);
- 4 - anterior median fissure (fissura mediana ventralis (anterior));
- 5 - lumbosacral thickening (intumescentia lumbosacralis);
- 6 - conus medullaris;
- 7 - terminal thread (filum terminale).
A - Cervicothoracic region:
- 1-medulla oblongata
- 2-posterior median sulcus
- 3-cervical thickening
- 4-posterior lateral groove
- 5-dentate ligament
- 6-hard shell
- 7-lumbosacral thickening
B – Lumbosacral region
- 1st posterior median sulcus
- 2-brain conus
- 3-end thread
- 4-ponytail
- 5-Dura mater of the spinal cord
- 6-Spinal ganglion
- 7-Thread (dura) of the spinal cord
The surface of the spinal cord is covered with longitudinal grooves and folds, which are the morphological boundaries of the structures. The anterior median fissure runs along the midline on the anterior surface, and the posterior median groove runs along the posterior surface.
Parallel to the anterior median fissure there are two anterolateral grooves, from which the anterior roots of the spinal nerves emerge. There are two pairs of grooves located parallel to the posterior median sulcus. Closer to the midline lie the posterior intermediate grooves, separating the wedge-shaped bundle of ascending fibers and the thin bundle of ascending fibers (posterior cord of white matter), and laterally there are the posterolateral grooves, which include the dorsal roots of the spinal nerves.
Between the posterior lateral sulcus and the anterior lateral sulcus is the lateral cord of white matter, and between the anterior median fissure and the anterolateral sulcus is the anterior cord of white matter.
The spinal cord is surrounded by three membranes. The outer shell is a hard shell, behind it lies the middle one – the arachnoid shell. Directly adjacent to the spinal cord is the internal, soft shell spinal cord.
Spinal nerve injuries
Violation of conduction functions comes to the fore in cases of spinal cord injury. His injuries lead to extreme severe consequences. If the damage occurs in the cervical region, then the functions of the brain are preserved, but its connections with most muscles and organs of the body are lost. Such people are able to turn their heads, speak, make chewing movements, and in other parts of the body they develop paralysis .
Most nerves are of a mixed nature. Damage to them causes loss of sensation and paralysis. If the cut nerves are stitched surgically, nerve fibers grow in them, which is accompanied by restoration of mobility and sensitivity.
1 slide
Lesson #11. Spinal cord: structure, functions Orlova V.N., teacher of chemistry and biology, MAOU "Tarasovka Gymnasium", pos. Cherkizovo, Pushkinsky district, Moscow region
2 slide
Study the structure of the spinal cord and the functions it performs in our body. Stimulate the development of cognitive interest Predict the consequences for a person of dysfunction of the spinal cord Lesson objectives:
3 slide
The spinal cord is located in the spinal canal and in adults it is a long (45 cm in men and 41-42 cm in women) cylindrical cord, weighing 30-40 g and about 1 cm in diameter. The spinal cord begins at the level of the foramen magnum of the skull and ends in a conical pointed, at the level of the 2nd lumbar vertebra. The spinal cord is much shorter than the spine and because of this, the nerve roots extending from the spinal cord form a thick bundle, which is called the “cauda equina.”
4 slide
Structure: Five sections: cervical, thoracic, lumbar, sacral, coccygeal Length 45 cm in men (41-42 in women) Weight 30 g Diameter 1 cm Surrounded by three membranes: Hard Arachnoid Soft Spinal cord Has two thickenings: cervical, associated with innervation arms, and lumbar, associated with the innervation of the legs. The nervous system is formed by the brain and spinal cord, as well as all their branches - nerves and ganglia. The nervous system is a huge community consisting of more than ten billion coherently working cells - neurons. The oldest and most durable part of the human nervous system is the spinal cord. Today in the lesson you will get acquainted with the features of the external and internal structure and functions of the spinal cord. The spinal cord is located in the spinal canal and in adults it is a long (45 cm in men and 41-42 cm in women) cylindrical cord, weighing 30-40 g and about 1 cm in diameter. (Slide No. 3) The spinal cord begins at the level of the occipital magnum openings of the skull and ends with a conical point, at the level of the 2nd lumbar vertebra. The spinal cord is much shorter than the spine and because of this, the nerve roots extending from the spinal cord form a thick bundle, which is called the “cauda equina.”
5 slide
Spinal canal - filled with cerebrospinal fluid Gray matter White matter Transverse section of the spinal cord: It is divided into two symmetrical halves by the anterior and posterior longitudinal grooves. The cross section clearly shows that in the center of the spinal cord around the spinal canal there are cell bodies of neurons that form the gray matter of the spinal cord. Around the gray matter are located the processes of the nerve cells of the spinal cord itself, as well as the axons of the neurons of the brain and peripheral nerve ganglia coming into the spinal cord, which form the white matter of the spinal cord. In cross section, the gray matter looks like a butterfly; it distinguishes anterior, posterior and lateral horns
6 slide
Significance of cerebrospinal fluid Carrying out nutrients to the cells of the spinal cord Shock absorber Participates in the removal of metabolic products Has bactericidal properties Cerebrospinal fluid: Quantity: 120 – 150 ml per day Capable of being renewed up to six times a day
7 slide
8 slide
Slide 9
10 slide
Motor neurons (motoneurons) Cross section of the spinal cord: The anterior horns contain the bodies of motor neurons (motoneurons), along the axons of which excitation reaches the skeletal muscles of the limbs and trunk, causing them to contract.
11 slide
12 slide
Neurons sympathetic division autonomic nervous system Cross section of the spinal cord:
Slide 13
The spinal cord is divided into segments, from each of which a pair of mixed (i.e., containing motor and sensory fibers) spinal nerves arise. There are 31 such pairs in total. Each segment of the spinal cord innervates a specific part of the human body. The nerves of the cervical and upper thoracic segments innervate the muscles of the neck, upper limbs and organs located in the thoracic cavity. The nerves of the lower thoracic and upper lumbar segments innervate the muscles of the trunk and abdominal organs. The nerves of the lower lumbar and sacral segments control the functioning of the muscles of the lower extremities and organs located in the pelvic region
Slide 14
Functions of the spinal cord Reflex Gray matter Conductive White matter Conducting motor impulses to the muscles of the body along descending pathways Conducting sensitive impulses from the skin, tendons, joints, pain and temperature receptors Carrying out voluntary movements Along ascending pathways, connection between the brain and spinal cord
15 slide
Spinal cord injury Complete injury: There is complete loss of sensation and muscle function below the level of injury. Partial Damage: Body functions below the level of damage are partially preserved. In most cases of spinal cord injury, both sides of the body are equally affected. Injuries to the upper cervical spinal cord can cause paralysis of both arms and both legs. If the spinal cord injury occurs in the lower back, it can cause paralysis in both legs.
To use presentation previews, create an account for yourself ( account) Google and log in: https://accounts.google.com
Slide captions:
Structure and functions of the spinal cord
The spinal cord is located in the spinal canal and in adults it is a long (45 cm in men and 41-42 cm in women) cylindrical cord, weighing 34-38 g and about 1 cm in diameter. The spinal cord begins at the level of the foramen magnum of the skull and ends conical pointed, at the level of the 2nd lumbar vertebra. The spinal cord is much shorter than the spine and because of this, the nerve roots extending from the spinal cord form a thick bundle, which is called the “cauda equina.”
Structure: Five sections: cervical, thoracic, lumbar, sacral, coccygeal Surrounded by three membranes: Hard Arachnoid Soft Spinal cord
Gray matter White matter Cross section of the spinal cord:
The importance of cerebrospinal fluid Conducts nutrients to the cells of the spinal cord Shock absorber Participates in the removal of metabolic products Has bactericidal properties Cerebrospinal fluid: Quantity: 120 - 150 ml per day Capable of being renewed up to six times a day
The spinal cord is divided into segments, from each of which a pair of mixed (i.e., containing motor and sensory fibers) spinal nerves arise. There are 31 such pairs in total. Each segment of the spinal cord innervates a specific part of the human body. The nerves of the cervical and upper thoracic segments innervate the muscles of the neck, upper limbs and organs located in the thoracic cavity. The nerves of the lower thoracic and upper lumbar segments innervate the muscles of the trunk and abdominal organs. The nerves of the lower lumbar and sacral segments control the functioning of the muscles of the lower extremities and organs located in the pelvic region
Functions of the spinal cord Spinal cord Gray matter White matter Reflex function - takes part in motor reactions Conductor function - conduction of nerve impulses
Spinal cord injury Complete injury: There is complete loss of sensation and muscle function below the level of injury. Partial Damage: Body functions below the level of damage are partially preserved. In most cases of spinal cord injury, both sides of the body are equally affected. Injuries to the upper cervical spinal cord can cause paralysis of both arms and both legs. If the spinal cord injury occurs in the lower back, it can cause paralysis in both legs.
Anchorage The average length of the spinal cord is: 1. 40 cm 2. 45 cm 3. 50 cm
Consolidation Which element of the somatic reflex arc is located entirely in the spinal cord? 1) motor neuron 2) receptor 3) interneuron 4) working organ
Reinforcement What is indicated by the letter A in the figure? 1) gray matter 2) white matter 3) ganglion 4) spinal cord root
Fastening The number of spinal nerves is: 1. 21 pairs 2. 40 pairs 3. 31 pair
Homework Page 56 – 57, notes in notebooks.
STUDENTS 205 P BABENKO DARIA DMITRIEVNA
Slide 2: Spinal cord (lat. Medulla spinalis) -
organ of the central nervous system of vertebrates located in the spinal canal. Inside the spinal cord there is a cavity called the central canal (lat. Canalis centralis). The spinal cord is protected by soft, arachnoid and hard tissue meninges. The spaces between the membranes and the spinal canal are filled with cerebrospinal fluid. The space between the outer hard shell and the bone of the vertebrae is called the epidural and is filled with fatty tissue and a venous network.
Slide 3
Slide 4
The SM is an uneven thickness, compressed from front to back, 45 cm long in men and 41-42 cm in women. Near top edge The atlas SM, without sharp boundaries, passes into the medulla oblongata, and at the level of the 2nd lumbar vertebra it ends with the medullary cone, the thin apex of which passes into the filum terminale, which is attached to the 2nd coccygeal vertebra.
Slide 5
Slide 6
The length of the spinal cord in an adult ranges from 40 to 45 cm, the width is from 1.0 to 1.5 cm, and the weight is on average 35 g. There are 4 surfaces of the spinal cord: a somewhat flattened anterior one, a slightly convex posterior one, two almost rounded lateral ones, passing in the anterior and posterior The anterior median fissure and the posterior median sulcus divide the spinal cord into two symmetrical halves.
Slide 7
Slide 8
The spinal cord does not have the same diameter throughout. Its thickness increases slightly from bottom to top. Largest size in diameter there are two fusiform thickenings: in the upper part - this is the cervical thickening (lat. intumescentia cervicalis), corresponding to the exit of the spinal nerves going to upper limbs, and in the lower section - this is the lumbosacral thickening (lat. intumescentia lumbosacralis), - the place where the nerves exit to the lower extremities. Cervical thickening begins at level III-IV cervical vertebra, reaches the II thoracic, reaching its greatest width at the level of the V-VI cervical vertebra. The lumbosacral thickening extends from the level of the IX-X thoracic vertebra to the I lumbar vertebra, its greatest width corresponds to the level of the XII thoracic vertebra (at the height of the 3rd lumbar spinal nerve).
Slide 9
10
Slide 10
11
Slide 11
12
Slide 12
The SC segment is a segment of the SC corresponding to each pair (right and left) of the spinal nerves. In SM there is a trace. segments: 1. Cervical segments – 8 (C 1 -C 8); 2. Thoracic segments –12 (Th 1 -Th 12); 3. Lumbar –5 (L 1 -L 5); 4. Sacral – 5 (S 1 -S 5); 6. Coccygeal –1 (C o 1) Segments of the spinal column are shorter than the segments of the spinal column - vertebrae, because at embryonic development the spinal column grows faster.
13
Slide 13
14
Slide 14
There is Shipo's rule about the relationship between the segments of the spinal cord and the spinal column. In the cervical and upper thoracic regions, the spinal cord segments are located one vertebra above their corresponding vertebra. In the middle thoracic - two vertebrae higher, in the lower thoracic - three vertebrae higher. Therefore, the spinal cord ends at the level of the 2nd lumbar vertebra. Below this level, the spinal cord forms the cauda equina, which consists of the roots of the spinal nerves L 1 - C o 1, descending down to the corresponding intervertebral foramina.
15
Slide 15
16
Slide 16: NEURONS OF THE SPINAL CORD. HISTOLOGY
The human spinal cord contains about 13 million neurons, of which 3% are motor neurons, and 97% are intercalary neurons. Functionally, neurons of the spinal cord can be divided into 4 main groups: 1) motor neurons, or motor neurons, - cells of the anterior horns, the axons of which form the anterior roots; 2) interneurons - neurons that receive information from the spinal ganglia and are located in the dorsal horns. These neurons respond to pain, temperature, tactile, vibration, proprioceptive stimulation; 3) sympathetic and parasympathetic neurons are located predominantly in the lateral horns. The axons of these neurons exit the spinal cord as part of the ventral roots; 4) associative cells - neurons of the spinal cord’s own apparatus, establishing connections within and between segments.
17
Slide 17
18
Slide 18
19
Slide 19
In a cross section of the spinal cord, white and gray matter are distinguished. The gray matter is located in the center, has the shape of a butterfly or the letter “H”, and is formed by neurons (their diameter does not exceed 0.1 mm), thin myelinated and non-myelinated fibers. Gray matter is divided into anterior, posterior and lateral horns. In the anterior horns (they have a round or quadrangular shape) the bodies of efferent (motor) neurons are located - motor neurons, the axons of which innervate skeletal muscles. In the posterior horns (they are narrower and longer than the anterior horns) and partially in the middle part of the gray matter, the bodies of interneurons are located, to which afferent nerve fibers approach. In the lateral horns from the 8th cervical to the 2nd lumbar segments of the spinal cord there are the bodies of neurons of the sympathetic nervous system, from the 2nd to 4th sacral - the bodies of neurons of the parasympathetic nervous system.
20
Slide 20
21
Slide 21
The white matter surrounds the gray matter, it is formed by myelinated nerve fibers and is divided into anterior, lateral and posterior cords. In the posterior funiculi of the spinal cord there are ascending paths, in the anterior ones there are descending pathways, in the lateral ones there are ascending and descending pathways. These tracts connect different parts of the spinal cord to each other and to different parts of the brain. The spinal cord has a segmental structure (31 segments), on both sides of each segment there is a pair of anterior and a pair of posterior roots. The dorsal roots are formed by axons of afferent (sensitive) neurons, through which excitation from receptors is transmitted to the spinal cord, the anterior ones - by axons of motor neurons (efferent nerve fibers), through which excitation is transmitted to skeletal muscles. The functions of the roots were studied by Bell and Magendie: with unilateral transection of the dorsal roots, the animal experiences a loss of sensitivity on the side of the operation, but motor function is preserved; when the anterior roots are cut, paralysis of the limbs is observed, but sensitivity is completely preserved.
22
Slide 22
23
Slide 23
Association fibers also pass through the white matter of the spinal cord. They make connections between the segments of the spinal cord and form the anterior, lateral and posterior bundles of their own (lat. fasciculi proprii ventrales, laterales et dorsales), which are adjacent to the gray matter of the spinal cord, surrounding it on all sides. These bundles include: dorsolateral tract (lat. tractus dorsolateralis) - a small bundle of fibers located between the top of the posterior gray column and the surface of the spinal cord in close proximity to the dorsal root septal-marginal bundle (lat. fasciculus septomarginalis) - a thin bundle of descending fibers, closely adjacent to the posterior median fissure, can be traced only in the lower thoracic and lumbar segments of the spinal cord, the interfascicular fascicle (lat. fasciculus interfascicularis) - formed by descending fibers located in the medial part of the wedge-shaped fascicle, can be traced in the cervical and upper thoracic segments.
24
Slide 24
25
Slide 25: FUNCTIONS OF THE SPINAL CORD
The spinal cord is connected by afferent and efferent nerve fibers to the trunk and limbs. The spinal cord includes axons of afferent neurons, bringing impulses from the skin, motor apparatus (skeletal muscles, tendons, joints), as well as from internal organs and the entire vascular system. Axons of efferent neurons emerge from the spinal cord, carrying impulses to the muscles of the trunk and limbs, skin, internal organs, blood vessels. In lower animals there is greater independence in the functioning of the spinal cord. It is known that a frog, while maintaining the medulla oblongata and spinal cord, can swim and jump, and a decapitated chicken can take off. In the human body, the spinal cord loses its autonomy; its activity is controlled by the cerebral cortex.
26
Slide 26
27
Slide 27
The spinal cord performs the following functions: afferent, reflex, conductive.
28
Slide 28
The afferent function is to perceive stimuli and conduct excitation along afferent nerve fibers (sensitive or centripetal) to the spinal cord. The reflex function lies in the fact that the spinal cord contains reflex centers of the muscles of the trunk, limbs and neck, which carry out a number of motor reflexes, for example, tendon reflexes, body position reflexes, etc. Many centers of the autonomic nervous system are also located here: vasomotor, sweating, urination , defecation, genital activity. All reflexes of the spinal cord are controlled by impulses coming to it along descending pathways from various parts of the brain. Therefore, partial or complete damage spinal cord cause severe disturbances in the activity of spinal centers.
29
Slide 29
30
Slide 30
The conductive function is to transmit excitation along numerous ascending pathways to the centers of the brain stem and to the cerebral cortex. From the overlying parts of the central nervous system, the spinal cord receives impulses along descending pathways and transmits them to the skeletal muscles and internal organs.
31
Slide 31
32
Slide 32: RISING PATHS
formed by axons of receptor or interneurons. These include: Gaulle's bundle and Burdach's bundle. They transmit excitation from proprioceptors to the medulla oblongata, then to the thalamus and cerebral cortex. Anterior and posterior spinocerebellar tracts (Gowers and Flexig). Nerve impulses are transmitted from proprioceptors through interneurons to the cerebellum. Lateral spinothalamic tract transmits impulses from interoceptors to the thalamus - this is the route for receiving information from pain and temperature receptors. The ventral spinothalamic tract transmits impulses from interoreceptors and tactile receptors of the skin to the thalamus.
33
Slide 33
34
Slide 34: DOWN ROUTES
formed by axons of neurons of the nuclei, which are located in various departments brain. These include: Corticospinal or pyramidal tracts carry information from the pyramidal cells of the cerebral cortex (from motor neurons and autonomic zones) to skeletal muscles (voluntary movements). The reticulospinal tract - from the reticular formation to the motor neurons of the anterior horns of the spinal cord, maintains their tone. The rubrospinal tract transmits impulses from the cerebellum, quadrigemole and red nucleus to motor neurons and maintains skeletal muscle tone. Vestibulospinal tract - from the vestibular nuclei medulla oblongata to motor neurons, maintains body posture and balance.
35
Slide 35
36
Slide 36: SPINAL CORD REFLEXES
The operating principle of the segmental apparatus of the spinal cord is reflex arcs. Basic diagram of the spinal cord reflex arc: information from the receptor goes along sensory neuron, it switches to the interneuron, which in turn switches to the motor neuron, which carries information to the effector organ. The reflex arc is characterized by sensory input, involuntary, intersegmental, motor output. Examples of spinal reflexes include: Flexion (flexor) reflex - a protective type reflex aimed at removing a damaging stimulus (pulling the hand away from a hot one). Stretch reflex (proprioceptive) - prevents excessive stretching of the muscle. The peculiarity of this reflex is that the reflex arc contains a minimum of elements - muscle spindles generate impulses that pass into the spinal cord and cause monosynaptic excitation in α-motoneurons of the same muscle. Tendon, various tonic and rhythmic reflexes. In four-legged animals, an extensor impulse can be observed.
37
Slide 37
38
Slide 38: PATHOLOGIES
Damage to the spinal cord is called myelopathy and can lead, depending on the level of damage to the spinal cord, to paraplegia or quadriplegia. In case of chronic inflammatory reaction Ankylosing spondylitis may develop. Radicular syndrome - neuralgia of the spinal cord.
39
Slide 39
