THE INTERNAL MAXILLARY ARTERY 



553 



arises from the internal maxillary just before the latter enters the canal of the 

 pterygoid process. It passes upward and backward in the temporal fossa on the 

 deep face of the temporalis muscle, in which it ramifies. It sends a branch outward 

 to the masseter, and anastomoses with the superficial temporal and middle men- 

 ingeal arteries. 



In some cases the tympanic and middle meningeal arise from this artery. 



The second part lies in the alar canal and is about an inch (ca. 2 to 3 cm.) in 

 length. It gives off two branches- — the anterior deep temporal and the ophthalmic. 



1. The anterior deep temporal artery (A. temporalis profunda oralis) emerges 

 from the canal through the teni])()ial or small alar foramen, and passes upward in 

 the anterior part of the temporal fossa on the deep face of the temporalis muscle, 



Fig. 439. — Left Eye of Horse, Deeper Dissection. 

 The outer plate of bone has been removed behind the pterygoid crest to expose the vessels and nerves. 

 a, a. Remnants of periorbita; b, stump of rectus oculi superior; c, obliquus oculi inferior; ci, rectus oculi inferior; 

 e, rectus oculi lateralis; e' , retractor oculi; / rectus oculi internus; g, g, obliquus oculi superior; h, eyeball; i, 

 trochlear nerve; k, ophthalmic nerve; k' , nasal nerve; k", infratrochlear nerve; k'" , ethmoidal nerve; I, optic 

 nerve; m, frontal nerve; n, lacrimal nerve; o, zygomatic nerve; p, nerve to obliquus inferior (from oculomotor); 

 (/, maxillary nerve; r, infraorbital nerve; s, sphenoi:)alatine nerve; ^ great palatine nerve; », small palatine nerve; 

 i\ internal maxillary artery; w, buccinator artery (cut off); x, infraorbital artery; x' , malar artery; y, spheno- 

 palatine artery; 3, great palatine artery; z', small palatine (or staphyline) artery; 1, 2, stumps of zygomatic arch; 

 3, stump of supraorbital process; 4. facial crest; 5, temporal fossa; 6, ophthalmic artery; 7 , mu.scular branch of 6; 

 S, lacrimal arterj- (cut); 9, frontal artery; 10, anterior deep temporal artery; 11, ethmoidal artery. (After 

 EUenberger-Baum, Top. Anat. d. Pferdes ) 



in which it is chiefly distributed. It gives twigs to the orbital fat and the skin of 

 the frontal region. 



2. The ophthalmic artery (A. ophthalmica externa) emerges from the anterior 

 opening of the alar canal, and enters the apex of the periorbita or ocular sheath. 

 Within this it forms a semicircular liend under the rectus oculi superior and is 

 continued by the ethmoidal artery. Its branches are as follows: 



(a) The supraorbital or frontal artery (A. supraorbitalis)^ is a small vessel 

 which often arises from the anterior deep temporal or the internal maxillary. It 

 passes along the inner wall of the orbit in company with the nerve of the same 

 name to the supraorbital foramen, through w'hich it emerges. It is distributed to 

 the orbicularis oculi, the corrugator supercilii, and the skin of the supraorbital region. 



(6) The lacrimal artery (A. lacrimalis) runs upward and forward wathin the 

 ^ This vessel appears to represent both the supraorbital and frontal of man. 



