Cross extensor reflex. Reciprocal inhibition and innervation

Pathological reflexes appear when the pyramidal tract is damaged, when spinal automatisms are disturbed. Pathological reflexes, depending on the reflex response, are divided into extensor and flexion.

extensor pathological reflexes lower limbs. Highest value has a Babinsky reflex - extension of the first toe with dashed skin irritation of the outer edge of the sole, in children under 2–2.5 years old - a physiological reflex. Oppenheim reflex - extension of the first toe in response to running fingers along the tibial crest down to the ankle joint. Gordon's reflex - slow extension of the first toe and fan-shaped divergence of other fingers during compression of the calf muscles. Schaefer's reflex - extension of the first toe with compression of the calcaneal tendon.

Flexion pathological reflexes on the lower extremities. The most important is the Rossolimo reflex - flexion of the toes with a quick tangential blow to the balls of the fingers. Bekhterev-Mendel reflex - flexion of the toes when hit with a hammer on its back surface. Zhukovsky reflex - flexion of the toes when struck with a hammer on its plantar surface directly under the fingers. Ankylosing spondylitis reflex - flexion of the toes when struck with a hammer on the plantar surface of the heel. It should be borne in mind that the Babinski reflex appears with an acute lesion of the pyramidal system, for example, with hemiplegia in the case of a cerebral stroke, and the Rossolimo reflex is a late manifestation of spastic paralysis or paresis.

Flexion pathological reflexes on upper limbs. Tremner reflex - flexion of the fingers in response to rapid tangential irritations by the fingers of the examiner of the palmar surface of the terminal phalanges of the II-IV fingers of the patient. Jacobson's reflex - Weasel - combined flexion of the forearm and fingers in response to a hammer blow on the styloid process radius. Zhukovsky reflex - flexion of the fingers of the hand when struck with a hammer on its palmar surface. Bekhterev's carpal-finger reflex - flexion of the fingers of the hand during percussion with the hammer of the back of the hand.

Pathological protective, or spinal automatism, reflexes on the upper and lower extremities - involuntary shortening or lengthening of a paralyzed limb when pricked, pinched, cooled with ether or proprioceptive irritation according to the Bekhterev-Marie-Foy method, when the researcher produces a sharp active flexion of the toes. Protective reflexes are often flexion in nature (involuntary flexion of the leg at the ankle, knee and hip joints). The extensor protective reflex is characterized by involuntary extension of the leg in the hip and knee joints and plantar flexion of the foot. Cross-protective reflexes - flexion of the irritated leg and extension of the other are usually noted with a combined lesion of the pyramidal and extrapyramidal tracts, mainly at the level spinal cord. When describing protective reflexes, the form of the reflex response, the reflexogenic zone, is noted. the reflex evoking area and the intensity of the stimulus.

Neck tonic reflexes occur in response to stimuli associated with a change in the position of the head in relation to the body.

Magnus-Klein reflex - increased extensor tone in the muscles of the arm and leg, towards which the head is turned with the chin, flexor tone in the muscles of opposite limbs when turning the head; flexion of the head causes an increase in flexor, and extension of the head - extensor tone in the muscles of the limbs.

Gordon's reflex - delaying the lower leg in the extension position when evoking a knee jerk. The phenomenon of the foot (Westphal) is the “freezing” of the foot during its passive dorsiflexion. Foix-Thevenard's shin phenomenon - incomplete extension of the shin in the knee joint in a patient lying on his stomach, after the shin was kept in the position of extreme flexion for some time; manifestation of extrapyramidal rigidity.

Yanishevsky's grasping reflex on the upper limbs - involuntary grasping of objects in contact with the palm; on the lower extremities - increased flexion of the fingers and feet during movement or other irritation of the sole. Distant grasping reflex - an attempt to capture an object shown at a distance. It is observed with damage to the frontal lobe.

An expression of a sharp increase in tendon reflexes are clonuses, which are manifested by a series of rapid rhythmic contractions of a muscle or group of muscles in response to their stretching. Foot clonus is caused in a patient lying on his back. The examiner flexes the patient's leg in the hip and knee joints, holds it with one hand, and with the other hand grabs the foot and, after maximum plantar flexion, jerks the foot dorsiflexion. In response, rhythmic clonic movements of the foot occur during the time of stretching the calcaneal tendon. Clonus of the patella is caused in a patient lying on his back with straightened legs: fingers I and II grab the top of the patella, pull it up, then sharply shift it in the distal direction and hold it in this position; in response, a series of rhythmic contractions and relaxations of the quadriceps femoris muscle and a twitching of the patella appear.

Synkinesia is a reflex friendly movement of a limb or other part of the body, accompanying the voluntary movement of another limb (part of the body). Pathological synkinesis is divided into global, imitation and coordinating.

Global, or spastic, is called pathological synkinesis in the form of an increase in flexion contracture in a paralyzed arm and extensor contracture in a paralyzed leg when trying to move paralyzed limbs or when actively moving healthy limbs, tensing the muscles of the trunk and neck, coughing or sneezing. Imitative synkinesis is an involuntary repetition by paralyzed limbs of voluntary movements of healthy limbs on the other side of the body. Coordinator synkinesis manifests itself in the form of additional movements performed by paretic limbs in the process of a complex purposeful motor act.

of the brain provide the realization of the influences of the centers of the brain in the control of the musculoskeletal system, and also carry out their own reflexes and regulation muscle tone trunk, neck and limbs. If the nature of the response is taken as the unifying core of the limb reflexes, then all of them can be combined into four groups: 1) flexion, 2) extensor, 3) rhythmic and 4) postural reflexes.

A. Flexion reflexes are phasic and tonic. Phase reflexes are a single flexion of the limb with a single irritation of the skin or proprioreceptors. Simultaneously with the excitation of the motor neurons of the flexor muscles, reciprocal inhibition of the motor neurons of the extensor muscles occurs. Reflexes arising from skin receptors are polysynaptic, they have a protective value (Fig. 5.2). For example, immersing in a weak solution of sulfuric acid the foot of a spinal frog (a frog whose brain has been removed) suspended on a hook, or pinching the skin of a limb with tweezers causes the limb to withdraw due to its flexion at the knee joint, and with stronger irritation in the hip joint.

Rice. 5.2. Reflexes of the lower extremities.

And the arc of the flexion (protective) reflex; B duta cross extensor reflex; AT knee joints with muscles; G segment of the spinal cord; 1 irritation of skin receptors; 2 afferent path ();

3 efferent pathways (↓) from α-motor neurons of the flexion (C) and extension (P) centers. Interneurons: O--<тормозные, О--< возбуждающие

Reflexes arising from proprioceptors can be monosynaptic and polysynaptic, for example, cervical postural (postural) reflexes. Phase reflexes from proprioreceptors are involved in the formation of the act of walking. According to the severity of phase flexion and extensor reflexes, the state of excitability of the central nervous system and its possible violations are determined. Tonic flexion (as well as extensor) reflexes occur during prolonged stretching of the muscles, their main purpose is to maintain the posture. Tonic contraction of skeletal muscles is the background for all motor acts carried out with the help of phasic muscle contractions.

There are several flexion phase reflexes: elbow and Achilles proprioceptive reflexes, plantar skin reflex. The elbow reflex is expressed in flexion of the arm in the elbow joint when the hammer hits the tendon of the biceps muscle of the shoulder (m. bicepsbrachii) (when the reflex is called, the arm should be slightly bent at the elbow joint), its arc closes in the cervical segments of the spinal cord CV-CVI. The Achilles reflex is expressed in the plantar flexion of the foot as a result of contraction of the triceps muscle of the lower leg when the hammer strikes the Achilles tendon, the reflex arc closes at the level of the sacral segments SI-SII, the plantar reflex is the flexion of the foot and fingers with stroke stimulation of the sole, the reflex arc also closes at the level of SI- SII.

B. Extensor reflexes, like flexion reflexes, are phasic and tonic, arise from the proprioreceptors of the extensor muscles, and are monosynaptic. Phase reflexes occur in response to a single stimulation of muscle receptors, for example, when hitting the tendon of the quadriceps muscle below the patella. In this case, a knee extensor reflex occurs due to contraction of the quadriceps muscle: the motor neurons of the flexor muscles during the extensor reflex are inhibited by this postsynaptic reciprocal inhibition with the help of Renshaw's intercalary inhibitory cells (Fig. 5.3). The reflex arc of the knee jerk closes in the lumbar segments LII-LIV. Phasic extensor reflexes, like flexion reflexes, are involved in the formation of the act of walking.

Tonic extensor reflexes are a prolonged contraction of the extensor muscles during prolonged stretching of their tendons. Their role is to maintain posture. In the standing position, tonic contraction of the extensor muscles prevents flexion of the lower extremities and maintains an upright natural posture. The tonic contraction of the back muscles keeps the torso in an upright position, providing a person's posture. Tonic reflexes in response to stretching of the muscles (flexors and extensors) are also called myotatic.

B. Reflexes of posture redistribution of muscle tone that occurs when the position of the body or its individual parts changes. Posture reflexes are carried out with the participation of various parts of the central nervous system. At the level of the spinal cord, cervical postural reflexes are closed, the presence of which was established by the Dutch physiologist R. Magnus (1924) in special experiments on a cat. There are two types of these reflexes that occur when tilting and when turning the head.

When the head is tilted down (anteriorly), the tone of the flexor muscles of the forelimbs and the tone of the extensor muscles of the hind limbs increase, as a result of which the forelimbs bend and the hind limbs unbend. When the head is tilted up (posteriorly), opposite reactions appear: the forelimbs unbend due to an increase in the tone of their extensor muscles, and the hind limbs bend due to an increase in the tone of their flexor muscles. These reflexes arise from the proprioceptors of the muscles of the neck and fascia covering the cervical spine. Under conditions of natural behavior, they increase the chances of getting food that is above or below the head of the animal (Fig. 5.4).

The second group of cervical postural reflexes arises from the same receptors, but only when the head is turned or tilted to the right or left. At the same time, the tone of the extensor muscles of both limbs on the side where the head is turned increases, and the tone of the flexor muscles on the opposite side increases. The reflex is aimed at maintaining a posture that can be disturbed due to a change in the position of the center of gravity after turning the head. The center of gravity shifts in the direction of turning the head, it is on this side that the tone of the extensor muscles of both limbs increases (Fig. 5.5).

Rice. 5.4. Postural neck reflexes in a cat with a removed vestibular apparatus.

before changing the position of the head; when passively raising () and lowering (↓) the head

Rice. 5.5. Changes in muscle tone of the limbs when the head is tilted to the right (a) and to the left (b)

G. Rhythmic reflexes repeated repeated flexion and extension of the limbs. Examples are the rubbing reflexes in a frog, and the scratching and walking reflexes in a dog. The rubbing reflex consists in the fact that after lubricating the skin of the thigh with a solution of sulfuric acid, the spinal frog repeatedly rubs this area in an attempt to free itself from the irritant. Weak irritation of the skin of the lateral surface of the body in a dog causes scratching of this area with the hind limb - a scratching reflex (analogous to the rubbing reflex in a frog). The walking reflex is observed in a spinal dog suspended with straps in a stand.

It was indicated above that when the spinal segmental-reflex mechanisms are isolated from the cerebral cortex (damage to the pyramidal tract), in addition to changes in the reflexes existing in the norm, a number of pathological reflexes appear that are normally absent. Familiarity with them is of great diagnostic value.

Pathological finger reflexes. All pathological finger reflexes observed in the clinic, depending on the nature of the motor reaction when they are evoked, can be divided into two groups - extensor and flexion.

extensor reflexes. The most important representative of this group for the clinic is Babinsky's symptom, which is the most reliable sign of damage to the pyramidal tracts above the Lv - S1 segments. It lies in the fact that when a blunt object is held along the outer edge of the foot from the heel upward, instead of normal flexion of the fingers, a slow tonic dorsal extension of the thumb occurs. Sometimes the rest of the toes fan-shaped diverge. Often there is a dissociation of the reflex, when only a fan-shaped divergence of the fingers occurs (fan symptom).

What is the essence of this most important pyramidal symptom? Dorsal extension of the thumb is normally associated with other motor components of the complex act of walking. Each time you walk, following the touch of the sole to the ground, a dorsal extension of the thumb occurs. The biological significance of this movement is, obviously; in that when the sole is taken off the ground and when the foot is subsequently brought forward, the thumb does not cling to the ground. This link is closely linked with all other elements of the act of walking and it is difficult to single it out from a continuous series of successive movements. But when the spinal cord is released from the control of the pyramidal system, the individual components of the complex functional system of the step reflex begin to appear in an isolated form and in all their complete isolation.

Other pathological finger reflexes of the extensor group include the following.

Symptom of Oppenheim. Tonic extension of the thumb is caused by pressing the pulp of the thumb and forefinger along the crest of the tibia from top to bottom.

Gordon's symptom. The same effect is obtained by squeezing the patient's calf muscles with the fingers.

Schaeffer's symptom. Thumb extension is caused by compression of the calf tendon.

Grossman's symptom. The same effect is sometimes obtained by squeezing the little toe of the foot.

Flexion reflexes. Rossolimo's symptom is one of the most important reflexes in this group. It is caused by a short blow of the researcher's fingers on the pulp of the terminal phalanges of the II-V toes. In response, a reflex plantar flexion of these fingers is obtained.

The same reflex on the hands is obtained by applying a short blow to the pulp of the fingers of the pronated hand.

Symptom Mendel - Bechterew. The same flexion of the fingers is evoked when a hammer strikes the anteroexternal surface of the rear of the foot in the region of the IV-V metatarsal bone. The same reflex on the hands is caused by a hammer blow on the back of the hand.

Zhukovsky's symptom. Plantar flexion of the toes is achieved by applying a short hammer blow to the sole just below the toes. The same reflex is evoked on the hands when the hammer strikes the palmar surface of the hand.

Hirshberg's symptom. With dashed stimulation of the inner edge of the sole, flexion and turn of the foot inward is obtained.

Symptom of Wartenberg. With the left hand, the doctor firmly grasps the wrist of the patient's supinated hand from below. The doctor hooks the bent 4 fingers of his right hand to the corresponding 4 bent fingers of the patient. The patient is invited to continue to bend his fingers as much as possible (against resistance). In this case, the thumb turns out to be adducted, bent and turned inward across the palm. In healthy individuals, the thumb remains motionless or its terminal phalanx bends slightly.

Of all the listed pathological reflexes, extensor reflexes, and of them mainly Babinsky's symptom, are the earliest and most reliable symptom of damage to the pyramidal tract. It often occurs even when, due to the irradiation of inhibition to the segmental reflex apparatus of the spinal cord, all normal spinal reflexes are depressed and muscle tone is reduced.

As for the group of flexion reflexes, in most cases they occur in the later periods of the disease, often combined with an increase in reflex muscle tone. Some authors attribute the appearance of these reflexes to the defeat of both the pyramidal and extrapyramidal pathways.

defensive reflex. One of the most striking manifestations of spinal automatism as a consequence of the isolation of spinal reflex mechanisms from the overlying sections is the mentioned protective or defensive reflex. Its essence lies in the fact that when irritation (pain or cold) is applied to the sole of a paralyzed and numb leg, reflex flexion of the leg occurs in the hip and knee joints and dorsiflexion of the foot in the ankle joint. The reflex is also obtained when irritation is applied to the entire area located below the lower boundary of the break in the connection between the brain spinal cord. The reflex can also be induced by forced plantar flexion of the thumb or all fingers according to Marie Foix. Sometimes it is possible to obtain a cross-protective reflex: in one leg, when stimulated, triple flexion (shortening) occurs, in the other - extension (lengthening). So, alternately irritating one or another leg, it is possible to cause reflex synergy in the form of phase movements of “walking”. A necessary condition for the appearance of a protective reflex is the defeat of the pyramidal pathways. However, one defeat of the pyramids for the emergence of a protective reflex is still not enough. Obviously, only a more massive lesion across the spinal cord with involvement of the extrapyramidal pathways, combined with the irritative state of the afferent systems, creates the conditions for the emergence of a protective reflex. In the presence of an additional focus of constant irritation (in the posterior roots and internal organs), patients sometimes have a tendency to a constant flexion posture of the legs.

The protective reflex is often used in the clinic to establish the lower boundary of the pathological focus. The upper level to which the protective reflex is evoked corresponds to the lower limit of the supposed pathological process.

The protective reflex from the upper extremities is of less importance for topical diagnosis. It is also caused by pain or cold irritation of the skin. The form of responses depends on the initial position of the affected hand. Most often they are manifested by flexion of the forearm, flexion and pronation of the hand, flexion of the fingers, less often by extension of the forearm. With pronounced protective reflexes on the hands, the response sometimes takes on the character of rhythmic, sequentially occurring flexion and extensor movements of the hand.

One of the variants of the protective reflex can be considered the so-called dorsal adductor reflex. It is examined in a patient sitting with legs slightly apart. Hammer strikes the spinous processes of the vertebrae or, better, paravertebral (from the sacrum up or down). In patients with damage to the pyramidal tracts, adduction of both hips or one with a unilateral lesion is observed. The local diagnostic value of the dorsal adductor reflex is the same as the protective one: the upper limit from which the reflex is evoked corresponds to the lower limit of the supposed pathological focus.

Pathological synkinesis. Simultaneously with the appearance of pathological reflexes, the defeat of the pyramidal tracts is also accompanied by pathological synkinesis - friendly movements. The essence of synkinesis lies in the fact that due to the weakening of the inhibitory reactions of the cerebral cortex to the executive-motor apparatus, motor impulses fall not only into the corresponding segment, but also radiate to neighboring, sometimes very distant segments of their own and opposite side. Synkinesis is manifested by diverse friendly movements in the affected limbs, both with muscle tension on the healthy side, and on the affected limbs when the patient tries to make one or another movement.

There are three main types of synkinesis:

1. Global, or spasmodic, synkinesis: at the moment of strong muscle contraction in healthy limbs, with one or another movement on the paralyzed side, strong muscle tension is also obtained.

2. Coordination synkinesis: a variety of additional synergistic movements that occur during voluntary movements.

3. Imitative synkinesis: in paralyzed limbs, symmetrical movements are repeated that the patient makes with healthy limbs.

An example of global synkinesis is such a test, when in a patient with a strong clenching of the hand of a healthy hand into a fist, the paralyzed arm bends at the elbow joint. Some attribute here the appearance of involuntary movements in paralyzed limbs when coughing, sneezing, yawning, laughing.

There are a lot of tests for determining coordination synkinesis. These include Raimist's adductor and abductor symptom (if the patient's healthy leg is abducted or brought to the midline with resistance, the paralyzed leg is adducted or retracted accordingly), Shtrumpel's tibial phenomenon (if the patient, with resistance exerted by the researcher, tries to bend the paralyzed leg at the knee, it turns out simultaneous extension of the foot and sometimes the thumb), a symptom
Grasset-Gossel (when a patient tries to lift a paralyzed leg out of bed, a healthy leg reflexively clings to the bed), etc.

With imitation synkinesis, paralyzed limbs repeat such voluntary movements as flexion and extension of the fingers, pronation and supination of the hand, etc.

These synkinesias are the result of damage not only to the pyramidal tracts. Their origin is more complicated. An important role in the occurrence of synkinesis is played by subcortical formations and violations of their connections with the cortex. Most often, pathological synkinesis is observed when the internal capsule is damaged.

Babinski's reflex- slow extension of the big toe (isolated or combined with a fan-shaped divergence of the remaining fingers) in response to dashed stimulation of the sole. In children under one year old, it is normal. It is caused by deep dashed irritation applied by the handle of the malleus along the outer edge of the foot from the fifth toe or in the opposite direction (Fig. 9).

Rice. 9. Study of the pathological Babinski reflex.

Oppenheim reflex- extension of the big toe when holding (with pressure) the pulp of the thumb along the inner edge of the tibia to the foot. The movement should be sliding in the direction from top to bottom (Fig. 10).

Rice. 10. Study of the pathological Oppenheim reflex.

Gordon reflex- extension of the big toe while squeezing the calf muscles by hand (Fig. 11).

Rice. 11. Study of the pathological reflex of Gordon.

Schaeffer's reflex- extension of the big toe with compression or pinch irritation of the Achilles tendon (Fig. 12).

Rice. 12. Study of the pathological Schaefer reflex.

Flexion pathological reflexes

Reflex Rossolimo(Fig. 13) - rapid plantar flexion of the II-V toes with abrupt blows to the pulp of these fingers with the fingers of the examiner.

Rice. 13. Reflex Rossolimo.

Zhukovsky reflex(Fig. 14) - quick plantar flexion of the II-V toes when struck with a hammer in the middle of the sole, under the fingers.

Rice. 14. Zhukovsky reflex.

Bekhterev-Mendel reflexes- rapid plantar flexion of the II-V toes when tapping with a hammer on the rear of the foot, in the region of the III-IV metatarsal bones (Fig. 15).

Pathological reflexes arise as a result of damage to the pyramidal tract, which conducts impulses from the cerebral cortex to the spinal cord. passes from the anterior central gyrus of the cerebral cortex through the subcortical regions of the brain, the brain stem and ends in the cells of the anterior horns.

Pathological reflexes are observed not only in cases of damage to the pyramidal tract, but also in normal children aged 1-1.5 years (see above). There are pathological reflexes: a) carpal; b) foot (flexion and extensor); c) oral automatism.

hand reflexes are characterized by the fact that with various methods of evoking them, a reflex flexion of the fingers of the hand occurs - they “bow”.

Rossolimo's carpal symptom - the examiner applies a short jerky blow to the tips of the II-V fingers of the patient's hand with his fingertips (the hand is in the palm down position). In response, rhythmic flexion of the fingertips occurs.

Zhukovsky's symptom - the researcher strikes with a hammer on the palm at the base of the fingers. In response, rhythmic flexion of the fingertips occurs.

foot reflexes divided into extensor and flexion. The extensor foot reflexes are characterized by the fact that with various methods of evoking them, a reflex extension (extension) of the thumb occurs.

Babinsky's symptom is caused by holding the handle of the neurological hammer, the blunt end of the needle along the outer edge of the sole (Fig. 9). In response, there is an extension of the thumb or a fan-shaped divergence of the toes. In children under 1.5 years of age, Babinski's symptom is physiological and is normally caused.

Oppenheim's symptom is caused by holding the back surface of the middle phalanx of the II and III fingers along the anterior surface of the lower leg of the subject. In response, there is a reflex extension of the big toe (Fig. 10).

Gordon's symptom is caused by compression of the gastrocnemius muscle of the subject's leg (Fig. 11). In response, there is a reflex extension of the big toe.

Schaeffer's symptom is caused by contraction of the Achilles (Fig. 12). In response, there is a reflex extension of the big toe.

Flexion foot reflexes are characterized by the fact that the fingers, with various methods of irritation, “nod”, “bow”.

Symptom of Rossolimo - the examiner with his fingertips delivers a short blow to the tips of the II-V fingers from the plantar side of the foot of the examinee. In response, there is a reflex flexion of the fingers.

Zhukovsky's symptom - caused by a hammer blow in the middle of the sole at the base of the fingers. In response, there is a reflex flexion of the fingers.

Ankylosing spondylitis I - is caused by a blow of the hammer on the back of the foot in the region of the IV-V metatarsal bones. In response, there is a reflex flexion of the fingers.

Symptoms of oral automatism occur with bilateral damage to the cortico-nuclear pathways (paths from the cortex to the nuclei).

The palmo-chin reflex is caused by irritation of the palm. In response, there is a contraction of the muscles of the chin.

The labial proboscis reflex is caused by either a stroke irritation of the lips. In response, there is a protrusion of the lips.

Grasping reflexes occur when the frontal lobe is affected, along with symptoms of oral automatism, mental and speech disorders. There are several grasping reflexes.

The symptom of automated grasping occurs with stroke irritation of the palm. In response, there is a flexion of the fingers of the hand (the patient grabs the object).

A symptom of obsessive grasping - the patient grabs all the surrounding objects.

Along with pathological reflexes in paralyzed or paretic limbs, an increase in tendon and periosteal reflexes, muscle reflexes, and protective reflexes occur.

defensive reflexes- involuntary shortening or lengthening of a paralyzed limb (flexion or extension of it), which occurs in response to pain, temperature, cold irritation. For example, in response to a needle prick, the paretic limb bends into,. With a sharp painful flexion of the toes, flexion of the leg occurs in the hip, knee and joints.

Protective reflexes manifest themselves in different ways. If the paretic limb was bent, then after an injection, a sharp cooling - it unbends, if it is unbent - it bends. Similar phenomena are noted on the hands.