SECTION XIV 

 CERVICAL PLEXUS 



THE cervical plexus is formed by the anterior primary divisions 

 of the first four cervical nerves. The nerves emerge from the 

 intervertebral foramina behind the vertebral artery, and each 

 nerve is joined at once by a communicating branch from the 

 sympathetic ganglion. The plexus lies on the scalenus medius 

 muscle, and is covered by sterno-mastoid. The four nerves join 

 with another, forming a series of loops, from which the branches 

 of distribution arise. 



Branches. (1) Cutaneous to head, neck, and shoulder. 



(2) Muscular to muscles of neck and diaphragm. 



(3) Communicating to vagus, spinal accessory, hypoglossal, 

 and sympathetic. 



(1) The Cutaneous branches appear in the posterior triangle of 

 the neck. The three ascending ones turn upwards over posterior 

 border of sterno-mastoid, the three descending ones to the 

 clavicular region. 



Ascending Branches : (a) Small occipital supplies skin on back 

 of ear and on scalp over mastoid process. 



(b) Great auricular crosses sterno-mastoid obliquely upwards, 

 and supplies the scalp behind the ear, the lower part of the 

 pinna, and the skin over the lower part of the masseter and 

 the parotid gland. 



(c) Superficial cervical crosses straight over the sterno-mastoid 

 and supplies the skin over the anterior triangle of the neck. 



Descending Branches : One large trunk is formed whic 

 descends from beneath sterno-mastoid. It extends through the 

 posterior triangle of the neck and supplies . the skin over the 



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