Patellar reflex

“ The temperature has become normal. The patient has lost flesh to a considerable extent since the reception of the injury. The lower extremities are much wasted, especially the peroneal muscles. Patellar reflexes can be obtained, but the knee jerks are uncertain. Unevenly distributed paralysis exists in both lower extremities. Left—Sensation fairly [Pg 327] good throughout. Quadriceps very weak; does not react to electrical stimulation. Calf muscles act fairly. Anterior tibial and musculo-cutaneous groups are paralysed. ”

“ Stimulation of the skin of the hind foot by any of various stimuli that have the character of threatening the part with damage causes the leg to be flexed, drawing the foot up by steady maintained contraction of the flexors of the ankle, knee and hip. In this reaction the reflex arc is (under schematic provisions similar to those mentioned in regard to the scratch reflex schema) (i.) the receptive neurone, noci-ceptive, from the foot to the spinal segment, (ii.) the motor neurone to the flexor muscle, e.g. of hip (a short intra-spinal neurone) ”

“ It is a brief extension of the limb at the knee-joint, due to a simple contraction of the extensor muscle, elicited by a tap or other short mechanical stimulus applied to the muscle fibres through the tendon of the muscle. The jerk is obtainable only from muscle fibres possessed of neural tonus. If the sensory nerves of the extensor muscle be severed, the “jerk” is lost. The brevity of the interval between the tap on the knee and the beginning of the resultant contraction of the muscle seems such as to exclude the possibility of reflex development. ”

“ Even a weak stimulation of the noci-ceptive arcs arising in the foot often suffices to lower or abolish the knee-jerk or the reflex extensor tonus of the elbow or knee. If various species of reflex are arranged, therefore, in their order of potency in regard to power to interrupt one another, the reflexes initiated in receptors which considered as senseorgans excite sensations of strong affective quality lie at the upper end of the scale, and the reflexes that are answerable for the postural tonus of skeletal muscles lie at the lower end of the scale. ”

“ After a few days of essentially suggestive treatment with continued attempts at passive movements of the contracted joints (knee, ankle, toe) , with steady concentration of the patient’s attention upon the joints, a slight mobility in the toe joint on passive movement was obtained.
After a few more days, the ankle became passively mobile to some degree; the patient exerted a certain resistance to passive flexion of toes and ankle. A week later, reflex contractions of the toes could be evoked by deep pin-prick. ”

“ When a person in health is seated with one leg crossed over the other or with the legs dangling over the edge of a high bench or table, and a sudden blow is struck upon the tendon of the patella, the leg and foot will be spontaneously jerked forward. In locomotor ataxia, even from an early period, this tendon-reflex is abolished. In spastic spinal paralysis (lateral spinal sclerosis) it is exaggerated. ”

“ Insertion.—Pars lateralis is fused indistinguishably with M. vastus medialis; these two muscles form the main (middle) part of the patellar tendon, which also receives contributions from pars postica and Mm. femoritibialis internus, extensor iliotibialis lateralis, and extensor iliotibialis anticus; the patellar tendon attaches to the entire rotular crest of the tibia; the patella is situated in the proximal part of this tendon; some deep fleshy fibers of M. vastus lateralis pars lateralis and M. vastus medialis attach to the proximal edge of the patella. ”

“ Many subjects who appear to be irresponsive will respond very well when a point on the outer edge near the tibial insertion is percussed. The elbow reflex, which has the same signification for the upper extremity that the knee-jerk has for the lower, is elicited in the same manner. ”

“ Each reflex movement must of itself generate stimuli to afferent apparatus in many parts and organs - muscles, joints, tendons &c. This probably reinforces the reflex in progress. The reflex obtainable by stimulation of the afferent nerve of the flexor muscles of the knee excites those muscles to contraction and inhibits their antagonistics: the reflex obtainable from the afferent nerve of the extensor muscles of the knee excites the flexors and inhibits their antagonistics. ”

“ The ipselateral reflex is flexion at shoulder, elbow and wrist. The contra lateral fore limb at the same time is extended at shoulder, elbow and wrist. When the reflex spreads to the hind limbs the hind limb of the same side is extended at hip, knee and ankle, that of the crossed side is sometimes flexed at hip, knee and ankle, but sometimes is instead extended at hip, knee and ankle. The reflex sometimes spreads to the neck, causing the head to be turned toward the fore limb, which is the seat of the stimulation. ”

“ These reflex actions follow the arousing of the sense organ with no more delay than is required for the passage of the disturbance over the nervous pathway. There is a delay of a small fraction of a second at every nerve junction, which makes some reflexes slower in their action than others. For example, there is a reflex known as the knee jerk; this is an outward kick which results from a sharp blow on the front of the leg just below the knee. The kick follows so closely after the blow that there cannot be more than one or at the most two nerve junctions in the pathway. ”

“ Squeezing of muscles and stimulation of their afferent nerves and those of joints, &c., elicit reflexes. The primary reflex movement might be expected, therefore, of itself to initiate further reflex movement, and that secondarily to initiate further still, and so on. Yet on cessation of the external stimulus to the foot in the flexion-reflex the whole reflex comes usually at once to an end. The scratch-reflex, even when violently provoked, ceases usually within two seconds of the discontinuance of the external stimulus that provoked it. ”

“ Some of the facts brought forward by Babinski and Froment to demonstrate the differentiation of reflex paralyses from pithiatic disorders of motion are challenged in the records of this volume by others, as for instance, by Dejerine, Roussy, Marie, [xi] and Guillain. Babinski tells us that in pithiatism, properly so designated, the tendon reflexes are not affected. He believes that even in pronounced anesthesia of the lower extremities the plantar reflexes can always be elicited and are not abnormal in exhibition. ”

“ Reflex arcs from widely different parts conjoin and pour their influence harmoniously into the same muscle. The motor neurones of a muscle of the knee are the terminus ad quern of reflex arcs arising in receptors not only of its own foot, but from the crossed fore foot and pinna and tail, also undoubtedly from the otic labyrinth, olfactory organs and eyes. ”

“ Thus the flexion-reflex, if intense and prolonged, may, directly its own exciting stimulus is discontinued, be succeeded by a " spontaneous " reflex of extension, and this even when the animal is lying on its side and the limb horizontal - a pose that does not favour the tonus of the extensor muscles. Such a " spontaneous " reflex is the spinal counterpart of the visual " Lichthof." To this spinal induction, as it may be termed, seems attributable a phenomenon commonly met in a flexion-reflex of high intensity when maintained by very prolonged excitation. ”

“ Certain of the protective reflex movements call into play a large number of muscles, as in the balancing of the body when walking along a narrow ledge, or on a slippery pavement. The dodging motion of the recruit, when the first cannon ball passes over his head, is reflex and involuntary. ”

“ Compressive [Pg 253] strength is tested by compressing the oval. In order to test tractive strength, the dynamometer is fastened to a nail at the point C, and the patient pulls with all his strength at D. The effort is registered on a graduated scale and is of importance for detecting left-handedness and measuring the extraordinary force that is displayed in certain states of excitement.
Fig. 38
Dynamometer
Reflex Action consists of movements and contractions produced by an impression exciting the nerves of the cutis (cutaneous reflex) or tendons (tendinous reflex) . ”

“ The muscles which are supplied by its motor fibres are paralyzed; they no longer respond by contraction to the impulse of the will. No reflex movements can be excited in them either from the skin or the tendons. They lose their tonicity, which they derive from the spinal cord, and are relaxed, soft, and flabby. As the interrupted sensory fibres can no longer convey impressions to the brain, we might naturally look for an anæsthesia, a paralysis of sensation, in the parts to which they are distributed, as complete as is the loss of function in the muscles. ”

“ Origin by a strong tendon from the middle of the lateral border of the patella and by fleshy fibres from the ventral border of the lateral sesamoid.
The patellar tendon ends in a flattened head which passes ventrad over the lateral epicondyle of the femur and then curves distad; it is closely united with the lateral head of the gastrocnemius. The muscle ends in a thick tendon which passes through a sheath formed by the tendons of the gastrocnemius and soleus, and the fascia of the shank. The tendon passes over the grooved proximal end of the calcaneus onto its ventral surface. ”

“ When the flexion-reflex is elicitable poorly, as, for instance, in spinal shock or under fatigue or weak excitation, the crossed extension does not accompany the homonymous flexion and does not appear. But, where the flexion-reflex is well developed, if not merely one but both feet be stimulated simultaneously with stimuli of fairly equal intensity, steady flexion at knee, hip and ankle results in both limbs, and extension occurs in neither limb. The contralateral part of each reflex is inhibited by the homolateral flexion of each reflex. ”

“ In some instances, together with great increase of tendon reflex, we observe a transfer of the centrifugal impulse to other nerves of the same extremity, or across the spinal cord to nerves and muscles of the homologous limb. ”

“ Luxation of the Patella, or Stifle.—Under the influence of a severe blow, a sudden leap or strain, the patella, or knee-pan is sometimes displaced. The animal holds his leg stiff and extended, cannot rest on it, and when obliged to walk, draws it along. This displacement of the patella is called being STIFLED. The displacement can be reduced by the aid of sufficient help, and placing a side-line with a hopple on the pastern of the affected limb, and drawing the hind leg forward, the surgeon will then, with both hands, bring the bone to its place. ”

“ The reflex arcs concerned in reflex maintenance of this tonic contraction of muscles have been shown in several cases to arise within those muscles, and in those very muscles which themselves exhibit the tonic contraction, It is not, however, certain that all muscles exhibit a reflex tonus: for instance, it is not certain that in the dog the tail muscles exhibit such a tonus. And in those muscles which do exhibit the spinal reflex tonus attempts to obtain a similar untiring slight steady reflex contraction by artificial stimuli applied to receptive organs or nerves have failed. ”

“ I have since made up my mind that his nerve-fibre must have been of that inert sort which transmits waves of sensation but slowly, so that the perception of the first blow reached the interior of his helmet just about as the second descended. At all events, he jerked back his foot, and somehow, between the involuntary contraction of his flexor muscles from pain and the glancing of my stick, his foot slipped from the stirrup. ”

“ If such a set of holds is lacking altogether, he will be employing press holds with the hands, lever holds with arm or leg, twisted pressure-thrusts from his foot and ankle against one wall to his knee against the other—any device that will relieve him of direct pulls and will leave his body free to help him at any second with some balance adjustment. For, once the body is really jammed up against the rock or in a crack, arms and legs are usually working only against one another or [Pg 166] against the friction of shoulders or thighs, and the mechanism can merely struggle and exhaust itself. ”

“ In the simplest form of apparatus locomotion is expected to be accomplished by the action of muscles inserted above the seat of the paralysis. Thus, when the muscles passing over the ankle-joint are paralyzed, the foot is moved as a dead weight by means of the quadriceps extensor, popliteus, and hamstring muscles inserted at the upper extremity of the leg. ”

“ The exciting cause, or that which called her attention to her foot, was the alleged slipping of the tendon of the peroneus longus muscle where it passes under the outer ankle-bone. She had no theory, fancy, or any other sentiment regarding her lameness whatever. She simply dropped her toes when walking, and was obliged to lift that limb very high to advance the foot and prevent stumbling. When, in examining her, I asked her to raise the foot, she was unable to do so. The muscles moving the ankle-joint were powerless. ”

“ They all three pass to their termination on the anterior tubercle of the tibia. The external ligament is the strongest, and the internal ligament the least developed.
In the dog, the cat, the pig, and the sheep, the patellar ligament consists of a single band. The articulation is further strengthened on the sides by lateral ligaments—an internal and an external.
With regard to the principal movements, these are flexion and extension, to which may be added movements of rotation of limited extent. In flexion, the leg bends on the thigh; its inferior extremity is directed upwards and backwards ”