Long Head Of Biceps BrachiiEdit

The long head of the biceps brachii is a tendon that links the upper arm to the forearm through a distinctive course that traverses the shoulder joint before contributing to forearm movement. It is one of the two heads of the biceps brachii muscle—the other head originates from a different site—and together they act as a versatile flexor and supinator of the forearm. The long head tendon is clinically important because its origin, course, and relationship to the glenohumeral joint can influence shoulder mechanics and be involved in common athletic and overuse injuries.

The tendon’s anatomy and its integration with nearby structures help explain both normal function and pathology. A precise understanding of its attachments, nerve supply, and vascularization supports diagnosis and treatment in sports medicine, orthopedics, and physical therapy. The long head tendon’s relationship to the glenoid labrum and to the intertubercular groove of the humerus also makes it a focus in discussions of shoulder stability and degenerative disease of the shoulder complex.

Anatomy and relationships

• Origin and route
  • The long head of the biceps brachii originates from the supraglenoid tubercle of the [shoulder joint] glenoid and the superior rim of the glenoid cavity. From there, the tendon travels within the joint capsule, exiting the shoulder through the intertubercular groove (also called the bicipital groove) of the humerus. In the groove, it is held in place by the transverse humeral ligament and lies adjacent to the humerus and the rotator cuff tendons.
• Distal attachment
  • Distally, the tendon merges with the short head of the biceps brachii to form the biceps muscle bellies, and the combined tendon inserts on the radial tuberosity. A fibrous extension called the bicipital aponeurosis fans out over the forearm fascia, contributing to the distal tendon’s stabilization and distribution of force.
• Relationships with surrounding structures
  • The long head tendon runs in close proximity to the glenohumeral joint and the superior labrum of the shoulder, and it can interact with the labrum during shoulder motion. Variations in anatomy are described in anatomical studies, with occasional accessory slips or deviations in trajectory reported in some individuals.

Attachments and contributions to movement

• Proximal attachments
  • Supraglenoid tubercle of the scapula
  • Superior glenoid rim
• Distal attachments
  • Radial tuberosity via the distal tendon
  • Bicipital aponeurosis
• Functional implications
  • The long head tendon contributes to elbow flexion and forearm supination, especially when the forearm is in a position of neutral or supination. Because the long head crosses the shoulder joint, it also plays a role in shoulder stabilization and proprioception. Activation of the long head tendon can be prominent during overhead activities and resisted flexion or supination movements.

Innervation and blood supply

• Innervation
  • The biceps brachii, including the long head, is innervated primarily by the musculocutaneous nerve (C5–C7). This nerve supplies the motor component that powers elbow flexion and forearm supination.
• Blood supply
  • Vascular input to the shoulder and upper arm region arises from branches of the brachial artery, with contributions to the distal biceps tendon from peri-tendinous vessels. Adequate blood supply supports tendon health and repair capacity.

Function and biomechanics

• Primary actions
  • Elbow flexion
  • Forearm supination
• Shoulder role
  • Because the long head passes through the shoulder, it can contribute to shoulder stability, particularly in maintaining the humeral head within the glenoid during certain movements. Its function is coordinated with the short head and adjacent shoulder muscles to produce smooth, controlled motion.
• Activity and loading
  • In athletes and laborers who perform overhead or forceful pulling actions, the long head tendon is frequently loaded, which can predispose it to wear, tendinopathy, or partial tears under repetitive stress.

Clinical significance

• Tendinopathy and tears
  • Long head tendinopathy and partial or full-thickness tears can cause anterior shoulder pain, weakness in forearm rotation, and tenderness near the bicipital groove. Overuse, repetitive overhead motion, and acute traction injuries are common etiologies.
• SLAP lesions and labral involvement
  • Because the long head tendon originates near the superior labrum, injuries to the labrum (such as SLAP lesions) can be associated with long head tendon pathology. Symptoms may include a catching sensation, clicking, or pain with throwing or overhead activities.
• Tendon rupture
  • Rupture of the distal biceps tendon is a distinct injury that may involve the distal attachment rather than the long head itself; however, athletes focusing on elbow flexion and forearm supination can experience acute weakness following tendon rupture.
• Physical examination and imaging
  • Clinicians employ a variety of tests to assess long head tendon pathology, including provocative maneuvers that stress the bicipital groove and labral region. Imaging modalities such as ultrasound and magnetic resonance imaging (MRI) help characterize tendon integrity, inflammatory changes, and associated shoulder pathology.

Imaging and diagnostic considerations

• Ultrasound
  • Dynamic ultrasound evaluation can visualize the long head tendon within the bicipital groove, assess for tendinopathy, tenosynovitis, or rupture, and evaluate related structures in real time during movement.
• Magnetic resonance imaging (MRI)
  • MRI provides high-resolution detail of the tendon’s origin at the supraglenoid tubercle, its intra-articular course, and its distal insertion, as well as the relationship to the glenoid labrum and other shoulder structures. MRI is useful in diagnosing SLAP lesions and concomitant rotator cuff pathology.

Variations and history

• Anatomical variation
  • While the standard description notes a consistent origin from the supraglenoid tubercle, anatomical studies document rare variants, such as accessory tendon slips or alternate paths that may influence clinical symptoms or tendon mechanics.
• Nomenclature
  • The long head is often discussed in relation to its counterpart, the short head of the biceps brachii, with the two heads combining to form the functional biceps muscle. The broader structure is commonly referred to as the biceps brachii, which has important implications in movement, strength, and rehabilitation planning.

See also

• biceps brachii
• glenoid
• supraglenoid tubercle
• intertubercular groove
• coracoid process
• musculocutaneous nerve
• brachial artery
• shoulder joint