612 THE BLOOD-VASCULAR SYSTEM OF THE OX 



(4) The masseteric artery resembles that of the horse, but is smaller. 



The superficial temporal artery is large and presents the following special 

 features: (1) Its transverse facial branch passes into the central part of the masse- 

 ter. (2) It gives off a branch which corresponds to the posterior meningeal artery 

 of the horse, enters the temporal canal, and ramifies in the dura mater, giving off 

 twigs to the external ear, the temporal muscle, and the frontal sinus. (3) It 

 usually gives off the anterior auricular artery. (4) Branches are supplied to the 

 frontalis muscle and the eyelids. (5) A large branch passes around the outer side 

 of the base of the horn-core, supi^lies the matrix of the horn, and anastomoses 

 across the back of the frontal eminence with the artery of the opposite side. 



The internal maxillary artery is less curved than in the horse and is entirely 

 extraosseous, since the alar canal is absent. The principal differential features in 

 its branching are as follows: 



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

 frontal branch enters the supraorl)ital canal and ramifies chiefly in the frontal sinus. 



(2) Several branches take the place of the internal carotid artery. One of 

 these enters the cranial cavity through the foramen ovale and several small ones 

 pass through the foramen which represents the foramen rotundum and foramen 

 lacerum orbitale of the horse. They concur with the vertel^ral and condyloid 

 arteries in the formation of an extensive rete mirabile 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 of the horse. 



(3) 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. 



(4) The infraorbital artery is large and emerges from the infraorl)ital foramen 

 to form the lateral nasal artery. 



(5) The palatine artery is smaller than in the horse and usually arises by a 

 common trunk with the si^henopalatine. 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 up]:)er lip. It forms a rete mirabile al)out the nasopalatine 

 canal and terminates in the mucous membrane of the anterior part of the nasal 

 cavity. 



ARTERIES OF THE THORACIC LIMB 

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

 At the ell)ow it becomes the median.^ The chief differential features in its l^ranches 

 are as follows: 



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

 The posterior circumflex artery sends branches backward and downward into the 

 tricejis, taking the place in part of the deep brachial artery. The thoracico-dorsal 

 artery supi^lies branches to the pectoral muscles and the tricejis as well as the teres 

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



2. The deep brachial artery is small. 



3. The superior collateral ulnar artery is often doul)le, and does not extend to 

 the carpus. 



The median artery (posterior radial artery) descends along the inner part of 

 the posterior surface of the radius and divides near the middle of the forearm into 

 the radial and ulnar arteries. It gives oft' at the upper third of the forearm the 

 common interosseous artery, a large vessel which anastomoses with the deep bra- 

 chial, passes through the proximal interosseous space, and descends (as the dorsal 

 interosseous) in the groove between the radius and ulna, and concurs in the forma- 

 tion of the rete carpi dorsale. At the distal end of the forearm it sends a branch 



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

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



