Question

For the efferent pathway start with the primary motor cortex in the precentral gyrus. For the efferent pathways be sure to describe the pyramidal and extrapyramidal efferent pathways. Which is involved in fine motor control? What plexus and arm nerve are involved in this motor control of the flexor digitorum profundus muscle? What role does the cerebellum play in the flexion or the index finger?

Answer 1

Pyramidal tract - refers to corticospinal tract. these are pathway of volunatry movement.

Extrapyramidal tract - referes to all the descending tracts other than corticospinal tracts. These tracts do not pass throug the medullary pyramids. These includes Basal ganglia and other descending tracts. Rubrospinal, tectospinal, reticulospinal and vestibulospinal tract.

Efferent pathway ::: Pyramidal pathway

Origin - 2/3rd from precentral gyrus and 1/3rd from post central gyrus

Crossing - occurs at spinomedullary junction. 80% of the fiber cross the median plain and continue as lateral corticospinal tract. The uncrossed fiber continue as ventral corticospinal tract.

Lateral corticospinal cord descents upto S4. The fibers for upper limb are located medially, while lower limb is located laterally.

Ventral corticospinal tract desents upto mid thoracic level and then crosses the median plane and synapse to other side.

These motor fiber originates from the ventral horn of the spinal cord in cervical region and forms the brachial plexus. Ulnara nerve and anterior interosseus nerve supply the flexor digitorum profundus.

Brachial plexus are involved in the motor controle of FDP.(flexor digitorum profundus)

Role of cerebellum - Cerebellum co-ordinates and fine tunes the all the movement of finger.