578 THE CERVICAL NERVES. 



h. The mastoid hranch is united to the posterior auricular branch of the facial 

 nerve, and ascends over the mastoid process to the integument behind the ear. 



c. The facial branches of the great amdcular nerve, which extend to the 

 integuments of the face, are distributed over the parotid gland. Some slender 

 filaments penetrate deeply thi'ough the substance of the gland, and communicate 

 with the facial nerve. 



Small occipital nerve. — The smaller occipital nerve varies in size, 

 and is sometimes double. It springs from the second cervical nerve, 

 and is directed almost vertically to the head along the posterior border 

 of the sterno-mastoid muscle. Having perforated the deep fascia near 

 the cranium, the small occipital nerve is continued upwards between 

 the ear and the great occipital nerve, and ends in cutaneous filaments 

 which extend upwards in the scalp ; it communicates with branches 

 from the larger occipital nerve, as well as with the posterior auricular 

 branch of the facial. It appears to supply sometimes the occipito- 

 frontalis muscle. 



The auricula?' hranclt is distributed to the upper part of the ear on the posterior 

 aspect, and to the elevator muscle of the auricle. Tliis amicular branch is an offset 

 from the great occipital nerve when the small occipital is of less size than usual. 



II. Superficial Descending Branches. 



Supraclavicular nerves. — The descending series of the superficial 

 nerves are thus named. There are tAvo of these nerves, or, in some 

 cases, a greater number. They arise from the third and fourth cervical 

 nerves, and descend in the interval between the sterno-mastoid and the 

 trapezius muscles. As they approach the clavicle, the nerves are aug- 

 mented to three or more in number, and are recognised as internal, 

 middle, and posterior. 



a. The iiitcrnal (suprasternal) branch, which is much smaller than the rest^ 

 ramifies over the inner half of the clavicle, and terminates near the sternum. 



h. The middle branch (supraclavicular), lying opposite the interval between 

 the pectoral and deltoid muscles, distributes some twigs over the fore part of the 

 deltoid, and others over the pectoral muscle. The latter join the small cutaneous 

 branches of the intercostal nerves. 



c. The external ox jJosterior hranch (supra-acromial) is dhected outwards over 

 the acromion, and the clavicular attachment of the trapezius muscle, and ends 

 in the integmnent of the outer and back part of the shoulder. 



III. Deep Branches : Inner Series. 



Connecting branches. — The cervical plexus is connected near the 

 base of the skull with the trunks of the pneumo-gastric, hypoglossal, 

 and sympathetic nerves, by means of filaments intervening between 

 those nerves and the loop formed by the first two cervical nerves in 

 front of the atlas (p. 560). 



Muscular branches. — Branches to the anterior recti muscles proceed 

 from the cervical nerves close to the vertebrae, including the loop 

 between the first two of these nerves. 



Two Iranclics to the ansa hypoglossi, one from the second, the other 

 from tlie third cervical nerve, descend over or under the internal 

 jugular vein, to form a loop of communication with the ramus de- 

 scendens noni, and aid in the supply of the muscles below the hyoid 

 bone (p. 5G7). 



Phrenic nerve. — The diaphragmatic or phrenic nerve passes down 

 through the lower part of the neck and the thorax to its destination. 



