Cubital Fossa - Borders & Contents

The Cubital Fossa is a triangular-shaped depression, located between the forearm and the arm on the anterior surface of the elbow, with the apex of the triangle pointing distally. It is also known as the “antecubital” because it lies anteriorly to the elbow. It is a space filled with different structures that makes up its content. It has three boundaries/borders, and it also has a floor and a roof.

Cubital Fossa 

Structures/Borders

• Apex - Imaginary line connecting the medial and lateral epicondyles

• Medial border - the pronator teres

• Lateral border - the brachioradialis

• The floor - formed by the brachialis and supinator muscles

• The roof - formed by the skin and fascia of the arm and forearm reinforced by bicipital aponeurosis (which is a sheet of tendon-like material that arises from the tendon of the biceps brachii). The bicipital aponeurosis forms a partial protective covering to the median nerve, brachial artery, ulnar artery, and radial artery.

Contents

The cubital fossa contains four structures which from medial to lateral are :

• The median nerve- The median nerve leaves the cubital between the two heads of the pronator teres. It supplies the majority of the flexor muscles in the forearm. It runs distally in the arm on the lateral side of the brachial artery until it reaches the middle of the arm, where it crosses to the medial side and contacts the brachialis. The median nerve descends into the cubital fossa, where it lies deep to the bicipital aponeurosis and median cubital vein. The median nerve has no branches in the axilla or arm, but it does supply articular branches to the elbow joint.

• The brachial artery – The brachial artery provides the main arterial supply to the arm and is the continuation of the axillary artery. The brachial artery usually divides at the apex of the fossa into the radial and ulnar arteries which supplies the forearm, and it lies between the biceps tendon and the median nerve. The brachial artery may be felt pulsating deep to the medial border of the biceps. the medial and lateral epicondyles of the humerus are subcutaneous and can be easily palpated at the medial and lateral aspects of the elbow.

• The tendon of biceps brachii- It is a muscle of the anterior compartment of the arm. The biceps tendon runs through the cubital fossa, attaching to the radial tuberosity, just distal to the neck of the radius.

• The radial nerve- The radial nerves enters the arm posterior to the brachial artery, medial to the with the profunda brachii artery. Radial nerve It divides into superficial and deep branches. The radial nerve is in a deep groove also known as the radial groove between the brachioradialis and brachialis to the level lateral epicondyle of the humerus dividing into its superficial and deep branches. Anterior to the lateral epicondyle, the radial nerve divide into deep and superficial branches.

• Superficially, in the subcutaneous tissue overlying the cubital fossa are the median cubital vein, lying anterior to the brachial artery, the medial and lateral cutaneous nerves of the forearm, related to the basilic and cephalic veins.

Clinical Relevance

• Venipuncture – The area superficial to the cubital fossa is a common site used for the collection of venous blood specimens and blood transfusion. The basilic vein, median cubital vein, and cephalic vein are superficial veins that are frequently selected for venipuncture at the cubital fossa. The median cubital vein connects the basilic and cephalic veins, and it lies directly on the deep fascia, running diagonally from the cephalic vein of the forearm to the basilic vein of the arm. It crosses the bicipital aponeurosis, which separates it from the underlying brachial artery and median nerve, and it provides protection to the later. Because of its characteristics and visibility, it is easily accessible for the collection of the venous blood specimen. It may also be used for the insertion of a peripherally inserted central catheter.

• Brachial pulse and blood pressure- The brachial pulse can be palpated immediately medial to the biceps tendon in the cubital fossa. Also, when measuring blood pressure manually, a stethoscope is placed over the cubital fossa to auscultate the brachial artery for Korotkoff sounds.

• Supracondylar humeral fracture- Supracondylar fractures are the most common type of upper arm injury in children. It is an injury to the humerus, or upper arm bone, at its narrowest point, just above the elbow. They are frequently caused by a fall on an outstretched elbow or a direct blow to the elbow such as the median and the radial nerve. The displaced fracture fragments may impinge and damage the contents of the cubital fossa such as the median and radial nerve. Direct damage or post-fracture swelling can cause interference to the blood supply of the forearm from the brachial artery. The resulting ischemia can cause Volkmann’s ischaemic contracture.

• Cubital Tunnel Syndrome - Cubital tunnel syndrome is a peripheral nerve compression syndrome. It is an irritation or injury of the ulnar nerve in the cubital fossa at the elbow.