The cubital fossa is a triangular depression located on the anterior surface of the elbow joint. It serves as a passageway for various structures moving between the upper arm and the forearm. Understanding its anatomy is important in medical practice.
Defining the Cubital Fossa’s Location
Its boundaries create this distinct shape. The superior border, which forms the base of the triangle, is an imaginary horizontal line connecting the medial and lateral epicondyles of the humerus (the bone of the upper arm).
The medial border of this triangular space is formed by the lateral edge of the pronator teres muscle. The lateral border is defined by the medial edge of the brachioradialis muscle. The point where these two muscles converge forms the apex of the triangle. The floor of the cubital fossa is comprised of the brachialis muscle proximally and the supinator muscle distally, while the roof includes skin, fascia, and the bicipital aponeurosis.
Vital Structures Passing Through
Several important neurovascular structures traverse the cubital fossa. The brachial artery, which is the main blood vessel supplying the arm, passes through this area. Within the cubital fossa, this artery typically divides into two major arteries that supply the forearm: the radial and ulnar arteries.
Adjacent to the brachial artery is the median nerve, which plays a role in controlling movement and sensation in the forearm and hand. The tendon of the biceps brachii muscle also runs through the cubital fossa, attaching to the radial bone just below the elbow. Superficial to these deeper structures lies the median cubital vein, a prominent vein often visible beneath the skin. This vein acts as a connection between the cephalic and basilic veins.
Why This Area Matters Medically
The median cubital vein, being superficial and often large, is a primary site for venipuncture (drawing blood). Its stability and wide lumen make it an ideal choice for intravenous (IV) line insertion as well, facilitating the administration of fluids or medications. Healthcare professionals frequently select this vein for its ease of access and minimal discomfort for the patient.
The brachial artery is also used for medical procedures. Its pulse can be felt and is often used to measure blood pressure with a stethoscope and a blood pressure cuff. The brachial artery’s pulse can be palpated medial to the biceps tendon in this region. Additionally, the nerves passing through the cubital fossa, such as the median nerve, can be targeted for nerve blocks to provide pain relief or anesthesia for procedures in the forearm and hand.