Bicipital aponeurosis

Structure and location

Bicipital aponeurosis (aponeurosis m. bicipitis brachii, or Pirogov's aponeurosis) is a tendinous expansion. The fibers of the aponeurosis arise from the biceps tendon and run medially toward the cubital fossa. There, they blend into the deep fascia (fascia propria) of the upper limb. These fibers reinforce the fascia over the medial group of forearm muscles, giving it an aponeurotic appearance. At the medial margin of the cubital region, this fascia fuses with the ulna.

What passes beneath Pirogov's aponeurosis?

The aponeurosis crosses superficial to the medial neurovascular bundle.

Deep to the aponeurosis lie:

• Brachial artery (a. brachialis) — lies in the groove between the pronator teres (m. pronator teres) and the brachialis muscle (m. brachialis).
• Bifurcation of the brachial artery — 1–2 cm inferior to the line connecting the epicondyles of the humerus; the artery divides into two terminal branches: the radial and ulnar arteries.
• Median nerve (n. medianus) — in the lower third of the arm, it lies medial to the brachial artery.
• Deep veins — two venae comitantes (vv. brachiales) accompanying the brachial artery.

Topography of the branches of the brachial artery

Following the bifurcation of the brachial artery beneath the bicipital aponeurosis, its terminal branches course as follows:

• Radial artery (a. radialis) — runs laterally, crosses anterior to the tendon of m. biceps brachii, and enters the interval between the brachioradialis muscle (m. brachioradialis) and the pronator teres muscle (m. pronator teres).
• Ulnar artery (a. ulnaris) — passes deep to the pronator teres muscle and subsequently lies between the superficial and deep flexor muscles of the fingers.

(Note: high division of the artery above the cubital region is a normal variant — in such cases, a superficial brachial artery, a. brachialis superficialis, is formed.)

Surrounding structures and landmarks

The following topographical landmarks are found in the region of the bicipital aponeurosis:

• Muscles: m. brachioradialis and m. pronator teres.
• Superficial veins: v. mediana cubiti — an anastomosis in the cubital fossa. A communicating branch connecting v. mediana cubiti with the deep veins is also located here.
• Cutaneous nerves: cutaneous innervation of this area is provided by the medial cutaneous nerve of the arm (n. cutaneus brachii medialis) and the lateral cutaneous nerve of the forearm (n. cutaneus antebrachii lateralis).

Relation to the biceps brachii muscle

The aponeurosis is part of the distal attachment of the biceps brachii muscle (m. biceps brachii).

• Origin of the muscle: the long head arises from the supraglenoid tubercle of the scapula (tuberculum supraglenoidale), and the short head arises from the apex of the coracoid process (processus coracoideus).
• Insertion: distally, the muscle attaches via its main tendon to the radial tuberosity (tuberositas radii), and via its aponeurosis, it blends into the forearm fascia. The bicipitoradial bursa (bursa bicipitoradialis) is located in the area of tendon insertion.
• Function and innervation of the muscle: the biceps brachii is a strong forearm flexor and supinator. The muscle is innervated by the musculocutaneous nerve (n. musculocutaneus).

Class and exam questions

What else to study on this topic

• Biceps brachii muscle (m. biceps brachii)
• Brachial artery (a. brachialis)
• Cubital fossa (fossa cubiti)
• Deep fascia of the upper limb

Other topics in the "Anatomical Structures" section

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