412 CERVICAL PLEXUS. 



The Superficialis colli is formed by communicating branches from the 

 second and third cervical nerves ; it curves around the posterior border 

 of the sterno-mastoid and crosses obliquely behind the external jugular 

 vein to the anterior border of that muscle, where it divides into an ascend- 

 ing and a descending branch ; the descending branch is distributed to the 

 integument on the side and front of the neck, as low do\vn as the clavicle ; 

 the ascending branch passes upwards to the submaxillary region, and 

 divides into four or five filaments, some of which pierce the platysma 

 myoides and supply the integument as high up as the chin and lower part 

 of the face, while others form a plexus with the descending branches of 

 the facial nerve beneath the platysma. One or two filaments from this 

 nerve accompany the external jugular vein. 



The Jiuricularis magnus, the largest of the three ascending branches of 

 the cervical plexus, also proceeds from the second and third cervical 

 nerve ; it curves around the posterior border of the sterno-mastoid, and 

 ascends upon that muscle, lying parallel with the external jugular vein, to 

 the parotid gland, w r here it divides into an anterior and a posterior branch. 

 The anterior branch is distributed to the integument over the parotid 

 gland, to the gland itself, communicating with the facial nerve, and to the 

 external ear. The posterior branch pierces the parotid gland and crosses 

 the mastoid process, where it divides into branches which supply the pos- 

 terior part of the pinna and the integument of the side of the head, and 

 communicate with the posterior auricular branch of the facial and with 

 the occipitalis minor. Previously to its division the auricularis magnus 

 nerve sends off several facial branches which are distributed to the cheek. 



The Occipitalis minor arises from the second cervical nerve ; it curves 

 around the posterior border of the sterno-mastoid above the preceding, 

 and ascends upon that muscle, parallel with its posterior border, to the 

 lateral and posterior side of the head. It is distributed to the integument 

 and to the muscles of this region, namely, to the occipito-frontalis, attollens 

 and attrahens aurem, and communicates with the occipitalis major, auri- 

 cularis magnus and posterior auricular branch of the facial. 



The Acromiales and Claviculares are two or three large nerves which 

 proceed from the fourth cervical nerve, and divide into numerous branches 

 which pass downwards over the clavicle, and are distributed to the inte- 

 gument of the upper and anterior part of the chest from the sternum to the 

 shoulder. 



The Communicating branches are filaments which arise from the loop 

 between the first and second cervical nerve, and pass inwards to commu- 

 nicate with the sympathetic, the pneumogastric, and the hypo-glossal 

 nerve. The three first cervical nerves send branches to the first cervical 

 ganglion ; the fourth sends a branch to the trunk of the sympathetic, or 

 to the middle cervical ganglion. From the second cervical nerve a large 

 branch is given off which goes to join the spinal accessory nerve. 



The Muscular branches proceed from the third and fourth cervical 

 nerves; they aie distributed to the trapezius, levator anguli scapulae, and 

 rhomboidei muscles. 



The Communicans noni is a long slender branch formed by filaments 

 from the first, second, and third cervical nerves ; it descends upon the 

 outer side of the internal jugular vein, and forms a loop with the descen- 

 dens noni over the sheath of the carotid vessels. 



