Question

Which of the following supplies (supply) the motor innervation of each hemidiaphragm? 

1. Vagus nerve (tenth cranial nerve) 

2. Phrenic nerve 

3. Lower thoracic nerves 

4. Glossopharyngeal nerve (ninth cranial nerve) 

     A. 1 only B. 2 only C. 1 and 4 only D. 2 and 3 only

Answer 1

A diaphragm is a major component for respiration. It is a double-domed sheet of skeletal muscles located at the rib cage. Its main function is separating the thoracic cavity and abdominal cavity. During respiration when a person inhales the diaphragm contracts creating more volume for the thoracic cavity to expand increasing the air intake volume. Whereas during exhaling the diaphragm slowly relaxes to its original position maintaining the thoracic and abdominal volumes. The diaphragm is divided as left and right halves named as hemidiaphragm. Both these halves receive motor innervation from the phrenic nerve.

Thus the correct option is B.

Answer 2

15.Ans: B .2 only

Reason: the left half of diaphragm (hemidiaphragm) is innervated by left phrenic nerve and the right half is innervated by the right phrenic nerve.