DISSECTION OF THE HEAD AND NECK. 191 



Wharton's duct in position, and then remove the remainder of the gland 

 together with the stylo-hyoid, the digastricus, and the remains of the 

 stylo-maxillaris. This will expose the posterior part of the guttural 

 pouch, the pharynx, the larynx, the pharyngeal lymphatic glands, the 

 upper part of the external carotid artery (and its terminal branches — the 

 external and internal carotids, and the occipital), the superior cervical 

 ganglion of the sympathetic (and the upper part of the cervical cord), 

 the first parts of the 9th, 10th, 11th, and 12th cranial nerves, and the 

 inferior primary branch of the 1st cervical nerve. 



Pharyngeal Lymphatic Glands. These form an elongated cluster 

 situated at the upper part of the side of the pharynx. They are placed 

 on the course of all the lymphatic vessels of the head. 



The Common Carotid Artery (Plate 32) divides above the cricoid 

 cartilage of the larynx, and under cover of the submaxillary gland 

 or the stylo-maxillaris muscle, into three branches, viz., external 

 carotid, internal carotid, and occipital arteries. The first of these con- 

 tinues the direction of the parent trunk, and is much larger than either 

 of the others, which are of nearly equal size. 



The Occipital Artery (Plate 32). The root of this vessel is external 

 to, and slightly in advance of, the root of the internal carotid. It passes 

 upwards and slightly forwards over the anterior straight muscles of the 

 head, and enters the antero-external foramen of the atlas. In the 

 groove which connects this and the antero-internal foramen, the artery 

 divides into occipito-muscular, and cerebro-spinal branches. Before its 

 passage through the foramen the vessel detaches three collateral 

 branches, viz., prevertebral, mastoid, and retrograde or anastomotic 

 arteries. 



1. The Prevertebral Artery. — This is the first and most slender of the 

 three branches. Passing upwards and forwards, it supplies muscular 

 twigs to the anterior straight muscles of the head, and oneningeal twigs 

 that pass into the cranium by the foramen lacerum basis cranii and the 

 condyloid foramen. 



2. The Mastoid Artery, a considerable vessel, is detached about one- 

 third of an inch above the preceding. It crosses over the edge of the 

 rectus capitis lateralis, and ascends behind the styloid process of the 

 occipital bone, where it has already been exposed (page 170). 



3. The Retrograde or Anastomotic Branch varies considerably in 

 volume. Arising between the obliquus capitis superior and the rectus 

 capitis latei'alis, beneath the wing of the atlas, it passes backwards 

 through the posterior alar foramen, and anastomoses with the termina- 

 tion of the vertebral artery. 



The Internal Carotid Artery (Plate 32) is a long vessel which is 

 the main source of supply to the brain. It passes obliquely upwards 

 and forwards, supported by the membrane of the guttural pouch, and 



