Cubital Fossa

The cubital fossa is a triangular, fat-filled depression located on the anterior aspect of the elbow. This small area is anatomically important as it serves as a passageway for vascular and nervous structures passing between the upper arm and forearm. It is used as an anatomical landmark to identify the brachial pulse, as well as for performing common procedures like venipuncture, insertion of an intravenous (IV) catheter, and creating an arterio-venous fistula (AV fistula).

The cubital fossa is located anteriorly to the elbow joint. It has a superior, medial, and lateral border, as well as a roof and a floor. The superior border consists of an imaginary line joining the medial and lateral epicondyles of the humerus; the lateral border is the brachioradialis muscle; and the medial border is the pronator teres muscle. Deep within this region is the floor of the cubital fossa, which is formed by the brachialis and supinator muscles. Finally, the roof is formed by the antebrachial fascia and the bicipital aponeurosis from the biceps brachii, as well as the overlying skin and subcutaneous tissue.

The cubital fossa contains several important structures. From medial to lateral, the median nerve travels medially to the brachial artery and the biceps brachii tendon, eventually entering the forearm between the two heads of the pronator teres muscle. The brachial artery bifurcates into the radial artery and cubital artery at the apex of the cubital fossa. More laterally, the tendon of the biceps brachii muscle gives rise to the bicipital aponeurosis. Finally, the radial nerve, found on the most lateral part of the fossa, lies in between the brachioradialis and brachialis muscles. 

Understanding the anatomy of the cubital fossa has several clinical uses. First, the brachial pulse can be identified more easily by palpating the brachial artery, which is medial to the biceps tendon in the cubital fossa. Next, since the superficial veins of the cubital fossa are easily accessible, they’re often used for drawing blood and inserting intravenous catheters, as well as other procedures, like the creation of an AV fistula.

In preparation for dialysis, individuals typically undergo a surgical procedure to create the AV fistula, which is when an artery and vein are surgically ligated to create a dialysis access. The fistula causes extra pressure and blood to flow into the vein, turning it into a stronger blood vessel. The larger vein provides reliable, long-term access to vessels to allow large volumes of blood to be removed from the body through the dialyzer, which after filtration is returned to the body through the fistula. Without the fistula, regular hemodialysis sessions would not be possible, as untreated veins tend to collapse with repeated needle insertions.  

The cubital fossa is a fat-filled, triangular space situated anteriorly to the elbow joint. This small area is anatomically important as it serves as a passageway for vascular and nervous structures passing between the upper arm and forearm. Clinically, it is used as an anatomical landmark for the identification of the brachial pulse, as well as for performing important procedures like drawing blood, inserting IV catheters, and the creation of an AV fistula. From medial to lateral, the contents of the cubital fossa include the median nerve, the brachial artery, the biceps tendon, and the radial nerve.