214 THE ANATOMY OK THE HORSE. 



3. The Staphyline Nerve passes by the groove of the same name to the 

 soft palate. 



4. The Spheno-2X(latine Nerve enters the foramen of the same name, 

 and is distributed to the nasal mucous membrane. 



The Spheno-palatine (Meckel's) Gangliox. This is a small, greyish, 

 elongated and fusiform enlargement, generally adherent to the spheno- 

 palatine nerve. Slender branches radiate from it, and are divided into 

 afferent and efferent filaments. 



Aff'erent Filaments. — 1. The Vidian Nerve, which enters its posterior 

 extremity. This is a composite nerve foraaed by the unimi of the large 

 superficial petrosal branch of the 7th with a sympathetic filament. 

 Traced upwards, it entei's a minute foramen — the lower orifice of the 

 vidian canal. At the upper orifice of the canal it enters the sub- 

 sphenoidal confluent, and passes into the cavernous sinus by the foramen 

 lacerum basis cranii. There it separates into its petrosal and sympa- 

 thetic branches. 



2. Short bi-anches passing from the spheno-palatine nerve to the 

 posterior part of the ganglion. 



The vidian nerve is supposed to combine the motor and sympathetic 

 roots of the ganglion ; the spheno-palatine branches represent its sensoiy 

 root. 



Efferent Branches. — Some of these pass to the ocular sheath, to the 

 ophthalmic vessels, and to the muscles and other accessory pails of the 

 eye. Others join the spheno-palatine, palatine, superior dental, and 

 staph^'line nerves. The latter it is believed derives fi'om this source the 

 motor filaments which it conveys to the levator palati muscle. 



THE OCCIPITO-ATLANTAL ARTICULATION. 



This joint possesses two synovial sacs and an enveloping capsule, with 

 accessory fasciculi above and at each side which are sometimes dcsci'ibed 

 as distinct ligaments — the cruciform and styloid. 



The Occipito-Atlantal Ligament is membranous, and closes the 

 interval between the occiput and atlas. It is attached to the occiput at 

 the upper and lower edges of the foramen magnum, and to the outer side 

 of the condyles. Its posterior edge is fixed to the anterior border of the 

 atlas. The most superior fibres pass obliquely, the right and left fibres 

 intercrossing. This is the so-called cruciform ligament. On each side a 

 thickened coixl-like portion passes to be inserted into the styloid process 

 of the occipital bone, and these constitute the styloid ligaments. 



Synovial Sacs. Each of these belongs to an occipital condyle and its 

 receiving cavity on the front of the atlas. On the inner side each is 

 related to the dura mater and the occipital continuation of the odontoid 

 ligament, and elsewhere tliey are supported by the occipito-atlantal 

 ligament. 



