Page:Laboratory Manual of the Anatomy of the Rat (Hunt 1924).djvu/71

Rh (3) Deep artery of the arm. Leaving the distal end of the axillary artery, it sends branches to muscles of the upper arm (triceps), then proceeds distally along a spiral course, and finally sends branches down the anterior and lateral surfaces of the fore arm.

(4) The brachial artery, the continuation of the axillary, passes through the arm pit region, thence down the medial surface of the upper arm in company with the large nerves in this part of the arm. It lies throughout its length close to the posterior edge of the biceps brachii muscle. The artery provides branches for the muscles of the elbow region, but the main trunk passes down the forearm.

The second large arterial trunk leaving the aortic arch is the left common carotid artery. It originates from the aortic arch between the innominate artery and the origin of the left subclavian, and passes forward lateral to the trachea as far as the anterior end of the neck, where it splits into the external and internal carotid arteries.

The internal carotid artery proceeds anterodorsally from its origin and divides into two branches immediately posterior to the tympanic bulla. The dorsal branch of the two enters the tympanic bulla through the posterior lacerated foramen, which is situated on the median surface of the bulla immediately in front of the jugular process. The ventral branch enters the cranium by way of the carotid foramen.

The external carotid artery gives off the following branches.

(1) The occipital artery courses anterodorsally, from its origin immediately anterior to the internal carotid artery, passes around the median surface of the jugular process, thence dorsally to the dorsal musculature of the neck.

(2) The superior thyroid artery runs ventrally from its