DISSECTING MANUAL. 



(subclavian) below. The Digastric and the anterior belly of 

 the Omo-hyoid subdivide the anterior triangle into three tri- 

 angles, the digastric above, the carotid mesially, and the mus- 

 cular below. 



CERVICAL NERVES. 



Cervical Plexus. This is formed by the anterior primary 

 divisions of the first four cervical nerves; they emerge from 

 the spinal canal behind the vertebral artery and form loops on 

 the Rectus capitis lateralis and Scalenus medius under the 

 Sterno-mastoid. The branches, which arise from the loops, are 

 superficial (ascending and descending) and deep (external and 

 internal). [617] 



Superficial Branches (cutaneous). These pass under the 

 Sterno-mastoid to the posterior triangle. Ascending series: 

 The small occipital (C. 2 and 3) ascends along the posterior bor- 

 der of the Sterno-mastoid, pierces the deep fascia and divides 

 into the following branches: auricular, to the pinna; mastoid 

 and occipital, to the scalp; and cervical, to the upper neck. 

 It communicates with the great occipital, great auricular, and 

 posterior auricular. The great auricular (C. 2 and 3) ascends 

 on the Sterno-mastoid and divides below the ear into the fol- 

 lowing branches: mastoid, to the scalp ; auricular, to the lower 

 part of the pinna; and facial, to the lower part of the cheek. 

 It communicates with the small occipital, posterior auricular, 

 and (in the parotid gland) facial. The superficial cervical 

 (C. 2 and 3) runs across the Sterno-mastoid to its anterior bor- 

 der and divides into upper and lower branches for the neck in 

 front. It communicates with the infra-mandibular branch of 

 the facial. Descending series (C. 3 and 4) : A trunk descends 

 in the posterior triangle and divides into the following branches, 

 which pierce the deep fascia above the clavicle. The sternal 

 run over the clavicle internally, to supply the neck and chest 

 down to the end of the manubrium. The clavicular run over 

 the clavicle mesially, to supply the chest down to the nipple. 



[66] 



