Self-reflex

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A self-reflex is a reflex that produces an effect in the same organ that was previously stimulated. Paradigmatically, in neurophysiology, this usually refers to the muscle self-reflex (MER), which is triggered by muscle stretching via the Ia afferents via only one synapse ( monosynaptic ) to the alpha motor neuron in the spinal cord and via the efferents (motor nerves) to one visible twitching of the previously stretched muscle.

evaluation

The extent of the reflex response depends on the state of excitation of the motor neuron and the functional integrity of the structures involved in the reflex arc. The state of excitation of a motor neuron is influenced , among other things, by descending motor path systems , depth sensitivity and segmental interneurons . After a stroke , the muscles' own reflexes can increase in the affected muscle groups ( spasticity ). Then z. B. the stretching of a muscle also in functionally adjacent muscle groups from reflex twitches, that is, external reflexes are also clinically recognizable. Damage to the reflex arc itself, for example due to neuritis or mechanical damage, on the other hand, typically leads to a weakening of the muscles' own reflex.

Even the classic monosynaptic muscle reflex therefore does not follow a mechanically unchanged process, but can be influenced, for example, by learning, paying attention and voluntary tension. In contrast to external reflexes , self-reflexes are not habitable - repetition does not weaken or fail the reflex response.

Self-reflexes

Some muscle reflexes used in clinical neurological diagnostics . In the following list, the term affected nerve pathways refers to the nerves that absorb the stimulus and trigger the effect. As usual, the cranial nerves are represented in Roman numerals, the abbreviations C (neck), Th (chest) L (loin) and S (cross) indicate the corresponding spinal cord nerves .

Achilles tendon reflex

See main article: Achilles Tendon Reflex

Adductor reflex

  • also ADR
  • Triggered: Blow on the adductor tendons immediately proximal to the insertion on the epicondyle medialis femoris (inside of the thigh bone on the knee joint).
  • Effect: adduction of the leg in the hip.
  • Affected nerve tracts: L2, L3, L4, obturator nerve
  • Comment: When the reflex is increased, both legs react to a one-sided trigger.

Abdominal reflex

  • Trigger: Place your fingers firmly on the abdominal muscles and hit the back of your fingers
  • Effect: contraction of the abdominal muscles on the same side (ipsilateral)
  • Affected nerve tracts: Th6-L1
  • Comment: Not to be confused with the abdominal skin reflex

Biceps tendon reflex

Biceps femoris reflex

Extensor digitorum reflex

  • also Braunecker-Effenberg reflex, BER, finger extension reflex
  • Triggering: Strike the extensor digitorum muscle with fingers slightly to moderately flexed.
  • Effect: extension of the fingers D2-D4 (index, middle and ring fingers)
  • Affected nerve tracts: C6, C7, radial nerve Ramus profundus
  • Comment: BER is one of the deep tendon reflexes and is slightly superior to the biceps tendon reflex and the brachioradialis reflex in terms of sensitivity and specificity in terms of neurological information

Flexor reflex

  • also finger flexor reflex, Trömner reflex (named after Ernst Trömner ), snap reflex, cinema reflex, Mayerscher joint reflex, Hoffmann reflex
  • Trigger: stretching the flexor muscles of the fingers; Safest release (according to Wartenberg): The examiner's index finger is placed across the loosely flexed fingers of the patient and the index finger is struck with the reflex hammer .
  • Effect: The fingers are flexed
  • Affected nerve tracts: C7, C8, median and ulnar nerves
  • Comment: Contrary to older representations, it is not a certain spastic sign, but a self-reflex near the threshold.

Masseter reflex

  • also masseter temporalis reflex, mandibular reflex
  • Triggering: A reflex hammer blow from above against the lower row of teeth or the chin, which stretches the masseter and temporalis muscles .
  • Effect: the mouth is closed.
  • Affected nerve tracts: trigeminal nerve

Patellar tendon reflex

See main article: Patellar Tendon Reflex
  • also hamstring reflex, quadriceps reflex, PSR
  • Triggering: Brief blow to the patellar tendon with the knee joint bent (for example by crossing the legs).
  • Effect: The quadriceps femoris muscle is tensed and the leg in the knee joint is stretched.
  • Affected nerve tracts: L2, L3, L4 and femoral nerve

Pectoral reflex

  • Triggering: Stretching the tendon of the pectoralis major muscle by pressing against the chest and hitting the back of the fingers
  • Effect: adduction of the upper arm in the shoulder joint
  • Affected nerve tracts: C5 – C8

Pronator reflex

  • also pronation reflex
  • Release: With the forearm bent in the middle position between pronation and supination, a short blow is performed from the inside out on the processus styloidus radii.
  • Effect: the hand and forearm are pronated .
  • Affected nerve tracts: C6, C7, C8 and median nerve

Radius periosteal reflex

  • also RPR, brachioradialis reflex
  • Triggering: Hit the lower third of the radius with the forearm slightly bent in the middle position between supination and pronation.
  • Effect: flexion of the forearm in the elbow joint by tensing the brachioradialis muscle .
  • Affected nerve tracts: C5, C6 and radial nerve

Scapulohumeral reflex

Tibialis posterior reflex

  • also TPR
  • Triggered: strike against the tendon of the tibialis posterior muscle, i.e. above or below the inner ankle ( malleolus medialis )
  • Effect: The medial edge of the foot is lifted ( supination ).
  • Affected nerve tracts: L4, L5 and tibial nerve
  • Comment: The reflex is close to the threshold and therefore cannot always be triggered. In the case of disc damage in the lumbar region L4 / L5, this reflex is an important diagnostic indicator, but it can only be interpreted in a side-by-side comparison.

Triceps tendon reflex

  • also TSR, pocket knife reflex
  • Triggering: With the forearm bent, a blow is hit on the tendon of the triceps brachii muscle just above the olecranon .
  • Effect: The forearm is stretched.
  • Affected nerve tracts: C7, C8 and radial nerve

Toe flexion reflex

  • also Rossolimo reflex,
  • Triggering: The examiner hits the toe berries briefly and violently with his fingers.
  • Effect: The toes are bent.
  • Affected nerve tracts: S1 / S2, tibial nerve
  • Comment: The toe flexion reflex cannot usually be triggered. If it occurs, this is a diagnostic indication of damage to the central motor system.

See also

Individual evidence

  1. ↑ M.-J. Zhang et al .: Applying the Extensor Digitorum Reflex to Neurological Examination. In: J Nippon Med Sch Volume 77, Issue 5, 2010, pp. 250-253