710 THE BLOOD-VASCULAB SYSTEM OF THE OX 



The internal maxillary artery is entirely extraosseous, since the alar canal is 

 absent. It passes forward along the side of the pharynx and the lateral pterygoid 

 muscle and forms a double curve at the infratemporal fossa. It then runs forward 

 to the pterygo-palatine fossa and divides into two terminal trunks; one of these 

 divides into malar and infraorbital arteries, the other into sphenopalatine and 

 greater palatine. It gives off branches to the pterygoid muscles, and the principal 

 differential features in its branching are as follows : 



(1) The buccinator artery arises from the first curve of the internal maxillary; 

 it is relatively large, supplies the superior buccal glands, and divides into two 

 branches. One of these enters the buccinator; the other, which is much larger, 

 ramifies in the deep part of the masseter. 



(2) The anterior deep temporal artery usually arises by a common trunk with 

 the middle meningeal artery. The latter enters the cranial cavity through the 

 foramen ovale and concurs in the formation of the rete mirabile cerebrale. 



(3) The ophthalmic artery forms a rete mirabile within the periorbita.^ Its 

 frontal branch enters the supraorbital canal and ramifies chiefly in the frontal sinus. 



(4) Several branches which take the place of the internal carotid artery enter 

 the cranial cavity through the foramen orbito-rotundum. They concur with the 

 vertebral, middle meningeal, and condyloid arteries in the formation of an ex- 

 tensive rete mirabile cerebrale on the cranial floor around the sella turcica. From 

 each side of the rete an artery arises which is distributed in general like the internal 

 carotid and basilar arteries of the horse.^ 



(5) The malar artery is large; it arises by a common trunk with the infra- 

 orbital and gives off the dorsal nasal and the angular artery of the eye. 



(6) The infraorbital artery is large and emerges from the infraorbital foramen 

 to form the lateral nasal artery. 



(7) The greater palatine artery usually arises by a common trunk with the 

 sphenopalatine. It passes through the palatine canal and along the palatine groove, 

 enters the nasal cavity through the incisive fissure, and does not go to the upper lip. 

 It forms a rete mirabile about the incisive canal and terminates in the mucous 

 membrane of the anterior part of the nasal cavity. 



ARTERffiS OF THE THORACIC LIMB 



The brachial artery pursues the same course in the arm as that of the horse. 

 At the elbow it becomes the median.' The chief differential features in its branches 

 are as follows: 



1. The subscapular artery is almost as large as the continuation of the brachial. 

 The posterior circmnflex artery is large ; it sends branches backward and downward 

 into the triceps, taking the place in part of the deep brachial artery. The thoracico- 

 dorsal artery supplies branches to the pectoral muscles and the triceps as well as 

 the teres major and latissimus dorsi; it may arise directly from the brachial. 



2. The smallness of the deep brachial artery is compensated, as noted above, 

 by the large size of the posterior circumflex. 



3. The proximal collateral ulnar artery is often double, and does not extend to 

 the carpus. Its superficial descending branch goes to the superficial pectoral 

 muscle and the skin, and its ascending branch is distributed chiefly to the medial 

 head of the triceps and the anconeus. 



(4) The (distal) collateral radial artery, which is given off at the elbow joint, 



^ This may be distinguished as the rete mirabile orbitale. 



^ The arteries which concur in the formation of the rete may be termed the arterise retis 

 mirabihs cerebralis. 



^ The homologies of the vessels of the lower parts of the limbs are still uncertain. The ac- 

 coxmt given here is mainly based on the views of Sussdorf and Baum. 



