Arterial Supply to Upper Limb: Anatomy Overview

Overview of Arterial Supply to Upper Limb

• Focuses on the arteries of the upper limb, starting from the great vessels
• Begins with the aorta and its branches
• The arch of the aorta typically has three major arteries branching from it
• Left subclavian artery: supplies blood to the left upper limb
• Left common carotid artery: supplies blood to the head and neck
• Brachiocephalic trunk (formerly the nominate artery): branches to supply the right side of the body
• The brachiocephalic trunk splits into the right common carotid artery and the right subclavian artery
• Notes that anatomical variations exist and models aren't always correct

Importance of Critical Thinking in Anatomy

• Do not blindly trust any single source
• Multiple sources should be consulted
• Textbooks sometimes contain errors
• Simplifying information sometimes requires omitting or "faking" details
• Exceptions to the rule exist

Course of the Aorta and its Branches

• The aorta comes out of the left ventricle, arches to the left and posteriorly
• The arch of the aorta gives off the brachiocephalic trunk, left common carotid artery, and left subclavian artery
• The common carotid arteries supply the head and neck
• The brachiocephalic trunk divides into the right subclavian artery and the right common carotid artery
• Subclavian artery gives off the vertebral artery which runs through the transverse processes of the vertebrae and supplies blood to the brain

Transitions of the Subclavian Artery

• Subclavian artery passes the first rib, it changes its name to the axillary artery, as it enters the axilla (armpit)
• Stealth assassins should be aware that the axillary artery is not protected in the axilla

Axillary Artery and Pectoralis Minor

• Axillary artery runs through the axilla
• Brachial plexus surrounds the axillary artery
• Parts of the brachial plexus are named according to their position around the axillary artery
• Pectoralis minor muscle covers part of the axillary artery, dividing it into three segments:
  • First part: From the first rib to the border of pectoralis minor
  • Second part: Behind pectoralis minor
  • Third part: Continues past pectoralis minor

Branches of the Axillary Artery

• The axillary artery has one branch in its first part, two in its second part, and three in its third part
• First part branch:
  • Superior thoracic artery (supplies the superior thoracic region)
• Second part branches:
  • Lateral thoracic artery (supplies the lateral part of the thorax)
  • Thoracoacromial artery (supplies the thorax and acromion, going around the scapula)
• Third part branches:
  • Subscapular artery (supplies the subscapular region)
  • Anterior and posterior circumflex humeral arteries (circumflex arteries that go around the humerus)

Anastomoses Around Joints

• Presence of many arterial branches and anastomoses (interconnections between arteries) around joints like the shoulder/elbow prevent loss of blood to a limb
• Anastomoses provide collateral circulation
• If one artery is occluded, blood can flow through other arteries around the joint

Brachial Artery

• After the axilla, the axillary artery becomes the brachial artery at the lower border of teres major
• Brachial artery runs through the brachium (upper arm)
• The ulnar nerve runs around the "funny bone"
• The median nerve also runs alongside the brachial artery
• The brachial artery is palpable in the groove between the biceps and triceps muscles

Course of Brachial Artery at the Elbow

• At the cubital fossa (elbow), the brachial artery divides into the radial and ulnar arteries
• Radial artery: runs towards the thumb
• Ulnar artery: runs deep within the forearm
• Ulnar artery gives off interosseous branches
  • Supply blood to the posterior compartment (extensors)
  • Also, supply the deep anterior compartment of the forearm
• Radial artery: is fairly straightforward and swoops around towards the base of the thumb

Arterial Branches in the Forearm

• Arteries are interconnected by recurrent and interosseous branches
• Recurrent arteries go back up towards the elbow
• Presence of arteries around the elbow allows collateral circulation if main arteries are occluded

Radial and Ulnar Arteries at the Wrist

• Ulnar artery is deep in the forearm, but appears again at the wrist
• Radial artery is more superficial
• Ulnar artery passes over the flexor retinaculum with the ulnar nerve
• Radial artery passes posteriorly around the thumb through the anatomical snuffbox

Arterial Arches in the Hand

• Radial artery passes through the anatomical snuff box and enters the hand
• Radial and ulnar arteries meet to form superficial and deep palmar arches
• Palmar arches give off digital branches to supply the hand and digits with blood
• Structures in the hand (palmar aponeurosis, muscles) protect the arteries
• The hand has a rich blood supply

Clinical Considerations for Injuries to the Hand

• Stopping bleeding from a deep laceration in the hand can be difficult
• Compressing the radial or ulnar arteries at the wrist might not be effective
• Compressing the brachial artery higher up in the arm to reduce blood flow to the hand is an alternative
• Torniquets may be used as well, but must be released regularly to prevent damage to the tissues