DEEP BRANCHES OF THE CERVICAL PLEXUS. 



763 



The middle or supraclavicular branches cross the clavicle, and supply the 

 integument over the Pectoral and Deltoid muscles, communicating with the 

 cutaneous branches of the upper intercostal nerves. 



The external or supra-acromial branches pass obliquely across the outer surface 

 of the Trapezius and the acromion, and supply the integument of the upper and 

 back part of the shoulder. 



Rect. Cap. Lett, 



III 



\JZect. Ant. Major 

 )Rect. Ant. Minor 



' To Sympathetic 

 ) To Hypoglossal 



3 To Scalp and Occipito Frontalis 

 I To Auricle 



Mastoid 



Auricular 

 Facial 



Trapezius 



. with Spin. Accessory 



FIG. 409. Plan of the cervical plexus. 



Deep Branches of the Cervical Plexus. Internal Series. 



The communicating branches consist of several filaments, which pass from 

 the loop between the first and second cervical nerves in front of the atlas to the 

 pneumogastric, hypoglossal, and sympathetic ; of branches from all four cervical 

 nerves to the superior cervical ganglion of the sympathetic, together with a branch 

 from the fourth to the fifth cervical. 



Muscular branches supply the Anterior recti and Rectus lateralis muscles ; 

 they proceed from the first cervical nerve, and from the loop formed between it 

 and the second. 



The Communicans Hypoglossi (Fig. 406) consists usually of two filaments, one 

 being derived from the second, and the other from the third, cervical. These 

 filaments pass downward on the outer side of the internal jugular vein, cross in 

 front of the vein a little below the middle of the neck, and form a loop with 

 the descendens hypoglossi in front of the sheath of the carotid vessels (see 

 page 756). Occasionally, the junction of these nerves takes place within the 

 sheath. 



The Phrenic Nerve (internal respiratory of Belt) arises chiefly from the fourth 



