174 THE ANATOMY OF THE HORSE. 



capitis posticus muscles, where it gives (1) muscular branches to these 

 muscles, and (2) auricular branches already followed to the skin of the 

 ear. 



The 2nd Cervical Nerve issues by the foramen at the anterior edge 

 of the arch of the axis, where it is covered by the obliquus capitis 

 inferior. It divides into superior and inferior primary branches, the 

 latter of which has already been referred to (page 147). The superior 

 branch gives twigs to the superior and inferior oblique muscles of the 

 head, and is continued like the succeeding members of the cervical 

 series (page 158). 



The Occipital Artery. This vessel will be found ascending through 

 the antero-external foramen of the atlas, and dividing there into cerebro- 

 spinal and occipito-muscular branches. The former enters the spinal 

 canal by the antero-internal foramen ; the latter divides for the supply 

 of the muscles and other structures of the poll. 



The Retrograde or Anastomotic branch of the occipital artery will be 

 found issuing with a backward course from the posterior foramen of the 

 atlas, and inosculating with the termination of the vertebral artery. 



The Mastoid branch of the occipital artery will be found beneath 

 the obliquus capitis superior. It ascends behind the styloid process ; 

 and, crossing over the mastoid crest, immediately above the mastoid 

 process, it passes under the edge of the squamous temporal bone, and 

 enters the parietotemporal conduit, in which it anastomoses with the 

 spheno spinous branch of the internal maxillary artery. 



Veins. — Satellite veins accompany these arteries. 



THE INTERMAXILLARY SPACE. 



Directions. — Incise the skin along the middle line, from the mental 

 symphysis upwards, and raise it on each side as far as the edges of the 

 rami. 



Cutaneous Nerves. The skin of the intermaxillary space is supplied 

 by a nerve derived from the 2nd cervical nerve. It comes from the first 

 stellate group of cutaneous nerves already seen on the surface of the 

 mastoido-huoieralis; and, crossing obliquely downwards into the space 

 (the long axis of the head is supposed to be vertical), it extends to near 

 the symphysis of the lower jaw. 



The Panniculus. This is here extremely thin. It hardly forms a 

 continuous layer, but consists of muscular fasciculi scattered in an 

 aponeurosis. 



The Submaxillary Lymphatic Glands (Plate 27). This group of 

 glands is placed on the inner side of the horizontal ramus, a little above 

 the point where its edge is crossed by the submaxillary vessels and 

 Stenson's duct. It rests on the lower belly of the digastricus muscle, 



