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Task 3. Deep (prophound) spinal reflexes investigation

Biceps-reflex – is caused by irritation of muscle tendon above cubital joint by neurologic hammer. Answer reaction – hand flexion in cubital joint. The reflexes arc is closed at C5-C6. Afferent and efferent fibers are in muscular-cutaneous (skin) nerve structure.

Triceps-reflex- is caused by hammer shock on triceps-muscle tendon, on 1-1,5 cm upper of posterior process of ulna. Answer reaction- muscular contraction and antebrachium (fore-arm) extension. The reflexes arc is closed at C6-C8. The fibers are in medianus, radialis and muscular-cutaneous nerves.

Carpo-radialis reflex –is investigated by hummer shock onto awl-like processus of radius. Answer reaction – flexure in cubital joint and antebrachium pronation. Origin location: investigated person hand must be bended at obtuse angle in cubital joint; person’s examinated hand is supported by doctor’s hand at the locus between pronation and supination. The reflexes arc is closed at C5-C8. The fibers are in medianus, radialis and muscular-cutaneous nerves.

Knee jerk or patellar tendon reflex - is caused by light shock of hummer on musculus quadriceps femoris tendon. Answer reaction – tibia extension. The reflexes arc is closed at L2-L4. Sensor and motor fibers are in femoral nerve. Every doctor must know how to elicit knee jerk. Knee jerk can be elicited by tapping the patellar tendon after the knee is semiflexed by placing one knee over the other while sitting on a chair or edge of a table. Immediately after the tendon tap the quadriceps femoris muscle contracts and there is jerking forward of the leg. There can be some alterations in knee jerk. Knee jerk is decreased or lost in:

  • Lesions in afferent neuron e.g. tabes dorsalis (Neurosyphilis).

  • Lesions in center, e.g. poliomyelitis.

  • Lesions in efferent neuron, e.g. lower neuron i.e. nerve pathway from anterior horn cell to muscle.

  • During sleep and anaesthesia.

Knee jerk is increased or exaggerated in:

  • Upper motor neuron lesion.

  • Tetany, where there is increased neuromuscular excitability.

  • Neurotic subjects due to hyperexcitability of CNS.

Pendular knee jerk occurs in lesion of neocerebellum which is characterized by hypotonia. In this type of knee jerk:

  • Contraction of quadriceps is weaker than in normal knee jerk.

  • Relaxation of quadriceps is quicker than normal knee jerk leading to quick fall of the leg like a dead weight. This is followed by vibrations or swinging of the leg like a pendulum. Hence the name pendular knee jerk. Hypotonia is the cause of the pendular knee jerk.

Achilles’ reflex – the investigated person kneels on a chair for free feet hanging. To shock with hummer on achilles’ (calcaneus) tendon. Answer reaction – musculus gastrocnemius contraction and plantar foot flexion. The reflexory arc is closed at S1-S2. Sensor and motor fibers are in tibial nerve.

If prophound myotatic reflexes are decreased or lost it testifies to reflector arc links disturbances. If answer reaction to the irritation is increased with significant excitement irradiation and involving other muscular groups into the answer reaction, reflector field spreading - it testifies to suprasegmentory central nervous system disorder existence.

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