What is Which of the following statement(s) is/are true about phrenic nerve except - and explain in detail?
Ans is. 'C i.e., Formed in front of scalenus medius muscle Lies anterior to anterior scalenus muscle Phrenic nerve is a mixed nerve & carries motor fibres to the diaphragm & sensory fibres from the diaphragm, pleura, pericardium & pa of the peritoneum.Origin:It arise in the neck from the ant. rami of the 3rd, 4th & 5th cervical nervesIt is formed at the lateral border of the scalenus anterior, opposite the middle of the sternocleidomastoid at the level of the upper border of the thyroid cailage.Relations:It runs veically downwards on the ant. surface of the scalenus ant. & in this pa it is related anteriorly toPreveebral fasciaInf. belly of omohyoidTransverse cervical aerySuprascapular aeryInternal jugular veinSternocleidomastoid mus.Thoracic duct on left side.After leaving the ant. surface of the scalenus ant. the nerve runs downwards on the cervical pleura behind the commencement of the brachiocephalic vein. (on left side nerve leaves the scalenus ant. at a higher level & crosses in front of the .first pa of the subclan a.). Here it crosses the internal thoracic aery (either anteriorly or posteriorly) & enters the thorax behind the 1st costal cailage.