The Brachial Artery - A Comprehensive Long Answer with Clinical Correlations

1. Introduction

2. Origin

"The brachial artery is the major arterial supply to the arm and is the continuation of the axillary artery at the inferior margin of the teres major, deep and medial to the median nerve."

• Imaging Anatomy, Vol. 3

3. Course and Relations

Proximal arm

• Lies on the medial side of the arm, in the medial bicipital groove
• Rests on the medial head of the triceps, then on the coracobrachialis, and finally on the brachialis muscle
• The median nerve lies lateral to the artery at first, then crosses anterior to it at mid-arm to lie medial distally
• The ulnar nerve lies medial initially but deviates posteriorly at mid-arm level, passing posterior to the medial epicondyle (and does NOT pass through the cubital fossa)
• The basilic vein lies parallel to the artery medially
• Paired brachial veins accompany the artery on each side

Distal arm

• Moves anteriorly and laterally to assume a position midway between the medial and lateral epicondyles
• Can be compressed against the medial side of the humerus in the proximal arm
• Lies in the cleft between the biceps brachii and triceps brachii muscles (palpable along its full length)

Cubital fossa

• Enters beneath the bicipital aponeurosis (lacertus fibrosus)
• Lies medial to the biceps tendon and lateral to the median nerve
• The aponeurosis covers and protects both the brachial artery and median nerve
• Terminates at the apex of the cubital fossa by dividing into radial and ulnar arteries at the level of the neck of the radius

"In the proximal arm, the brachial artery lies on the medial side. In the distal arm, it moves laterally to assume a position midway between the lateral epicondyle and the medial epicondyle of the humerus." - Gray's Anatomy for Students

4. Termination

5. Branches

(a) Profunda Brachii Artery (Deep Artery of the Arm)

• The largest branch of the brachial artery
• Arises near the origin of the brachial artery, just below the inferior border of teres major
• Passes with the radial nerve through the triangular interval (bounded by the shaft of the humerus, inferior margin of teres major, and lateral margin of the long head of triceps)
• Winds around the posterior surface of the humerus in the radial (spiral) groove, deep to the lateral head of triceps
• Terminates as two collateral vessels:
  • Radial collateral artery - anastomoses with the radial recurrent artery
  • Middle (medial) collateral artery - anastomoses with the recurrent interosseous artery

(b) Superior Ulnar Collateral Artery

• Arises distal to the origin of the profunda brachii
• Accompanies (runs alongside) the ulnar nerve as it passes posterior to the medial epicondyle
• Anastomoses with the inferior ulnar collateral and posterior ulnar recurrent arteries

(c) Inferior Ulnar Collateral Artery

• Arises above the medial epicondyle
• Anastomoses with the anterior ulnar recurrent artery

(d) Muscular Branches

• Numerous branches to the muscles of the anterior compartment (coracobrachialis, biceps brachii, brachialis)

(e) Nutrient Artery to the Humerus

• Enters through a foramen in the anteromedial surface of the humeral shaft

6. The Cubital (Periarticular Elbow) Anastomosis

"The cubital anastomosis permits ligature of the brachial artery distal to the origin of the deep artery of the arm." - Color Atlas of Human Anatomy, Vol. 2

7. Surface Marking

• A line drawn from the apex of the axilla (arm slightly abducted) to the midpoint between medial and lateral epicondyles of the humerus represents the surface marking of the brachial artery.
• The artery is palpable along this entire course in the medial bicipital groove.
• Pulse point: Easily palpated in the medial bicipital groove, proximal arm, and in the cubital fossa.

8. Anatomical Variations

• Type I: The superficial brachial is dominant and divides into radial and ulnar arteries
• Type II: It runs parallel to the deep brachial artery and continues as the radial artery in the forearm
• Type III: It joins the brachial artery distally

"In approximately 20% of individuals the brachial artery gives off a superficial brachial artery that courses inferiorly superficial to the median nerve; it can be a high-branching radial artery (10%), high-branching ulnar artery (3%), or divide into radial and ulnar arteries (7%)" - Fischer's Mastery of Surgery, 8th ed.

9. Clinical Correlations

9.1 Blood Pressure Measurement

• When cuff pressure falls just below systolic pressure: sounds appear (systolic reading)
• When cuff pressure falls below diastolic pressure: sounds disappear (diastolic reading)

"The sphygmomanometer is a device that inflates a cuff around the midportion of the arm to compress the brachial artery against the humerus." - Gray's Anatomy for Students

9.2 Brachial Artery Puncture and Cannulation

• Arterial blood gas sampling
• Cardiac catheterization (Sones technique - brachial cutdown approach)
• Invasive blood pressure monitoring

• It lacks adequate collateral circulation (unlike the dual supply at the wrist)
• Risk of ischemic complications to the hand if thrombosis occurs
• Requires the arm to be extended, limiting mobility
• A longer catheter (10 cm) is required to traverse the elbow joint

"Although it appears safe for arterial puncture, the brachial artery does not have the anatomic benefit of the collateral circulation that is found in the wrist." - Roberts and Hedges' Clinical Procedures in Emergency Medicine

9.3 Supracondylar Fracture of the Humerus and Brachial Artery Injury

• Arterial spasm, thrombosis, or laceration
• Anterior compartment ischemia of the forearm
• If untreated: muscle necrosis replaced by fibrous tissue = Volkmann's Ischemic Contracture

1. Pain - especially with passive finger extension
2. Pallor of the hand and forearm
3. Pulselessness - absent radial pulse
4. Paraesthesia - tingling in the hand
5. Paralysis - inability to extend fingers/wrist

"The most serious complication is a compartment syndrome of the forearm, also known as Volkmann's ischemic contracture. This classically occurs following a displaced supracondylar fracture. Post-ischemic swelling increases pressure within the enclosed osteofascial forearm compartment..." - Tintinalli's Emergency Medicine

• Urgent reduction of the fracture
• If ischemia persists after reduction: emergency surgical exploration of the brachial artery
• Fasciotomy for compartment syndrome

9.4 Volkmann's Ischemic Contracture

• Post-ischemic muscle necrosis of the flexor compartment of the forearm
• Replaced by inelastic fibrotic tissue
• Produces a characteristic flexion contracture of the wrist and fingers with pronation of the forearm
• The median nerve is also compromised (the key nerve and artery involved)
• Prevention: early recognition and treatment is essential - "Extremities with signs of ischemia require emergency orthopedic consultation" (Tintinalli's Emergency Medicine)

9.5 Brachial Artery Injuries

• Penetrating trauma (stab/gunshot wounds)
• Blunt trauma with fracture/dislocation
• Iatrogenic (cardiac catheterization, IV drug injection)

• Proximal control by compressing the brachial artery against the humerus
• Access via longitudinal incision in the medial bicipital groove
• The median nerve crosses from lateral to medial in the distal arm - must be identified and protected
• Injuries proximal to the profunda brachii origin will compromise collateral circulation and are more likely to cause critical ischemia
• Injuries distal to the profunda brachii origin may be tolerated due to collateral flow
• Always check radial and ulnar pulses by palpation and Doppler before and after repair

9.6 Brachial Artery in the Cubital Fossa - Surgical Significance

• It covers the brachial artery and median nerve in the distal cubital fossa
• Separates the median cubital vein (used for venepuncture) from these deeper vital structures
• Must be divided when surgically exposing the brachial artery distally
• The aponeurosis prevents laceration of the brachial artery during routine venepuncture at the cubital fossa

9.7 Brachioradialis Arteriovenous Fistula (for Dialysis)

9.8 Blood Pressure Discrepancy (Differential Brachial Pressure)

• Subclavian artery stenosis (proximal to the brachial artery origin)
• Aortic dissection
• Thoracic outlet syndrome
• Atherosclerotic disease

10. Summary Table