The arm
Each subclavian artery becomes the axillary artery as it crosses the outer edge of the first rib, and the brachial artery at the lower edge of the armpit. The brachial runs down the inner side of the upper arm close to the humerus. Pressing it against the bone stops bleeding further down the arm.
In front of the elbow it divides into the radial and ulnar arteries. The radial runs down the thumb side of the forearm, and its pulse is the one felt at the wrist. The ulnar runs down the side of the little finger.
The front of the forearm, deep view: the brachial artery dividing below the elbow into the radial and ulnar arteries, Gray's Anatomy, 1918, figure 528Wikimedia Commons, Henry Vandyke Carter, Public domain (Gray528.png)
In the palm the two join in a superficial and a deep palmar arch, from which the fingers are fed. Because both arteries feed the arches, the hand keeps its blood supply when one of them is blocked.
The arteries of the front of the forearm and hand, superficial view, with the superficial palmar arch, Gray's Anatomy, 1918, figure 527Wikimedia Commons, Henry Vandyke Carter, Public domain (Gray527.png)
Sources
- Susan Standring (ed.), Gray's Anatomy, 42nd ed. (2020), chapters on the shoulder girdle and arm, the elbow and forearm, and the wrist and hand.
Prev: The brain's arteriesNext: Blood pressure