What is bicep brachii?

Biceps Brachii Muscle

Introduction

The biceps brachii is one of the most recognizable muscles in the human body due to its prominent appearance in the upper arm. Often associated with strength and aesthetic fitness, this muscle plays a crucial role in upper limb function, especially in lifting and rotational movements. Clinically, it is essential in assessing elbow and shoulder pathologies, and its dysfunction can significantly impact daily activities like lifting, pulling, or carrying.

Understanding its detailed anatomy, function, clinical assessment, and therapeutic approaches is vital for healthcare professionals and students in anatomy, physiotherapy, and sports science.

Anatomy of the Biceps Brachii

Origin

The biceps brachii has two heads:

  • Long head: Originates from the supraglenoid tubercle of the scapula.

  • Short head: Arises from the coracoid process of the scapula.

Insertion

Both heads converge into a single muscle belly and insert at the radial tuberosity of the radius and via the bicipital aponeurosis into the deep fascia of the forearm.

Nerve Supply

  • Musculocutaneous nerve (C5-C6), a branch of the lateral cord of the brachial plexus.

Function of the Biceps Brachii

The biceps brachii is a biarticular muscle—acting on both the shoulder and the elbow joints. Its primary functions include

  • Elbow flexion (especially when the forearm is supinated).

  • Forearm supination (it’s the most powerful supinator).

  • Assists in shoulder flexion.

  • Stabilizes the shoulder during arm movements.

Clinical Assessment of the Biceps Brachii

Palpation

  • Patient's elbow should be slightly flexed and supinated.

  • Ask the patient to flex the elbow against resistance.

  • The muscle belly becomes prominent in the mid-upper arm and can be palpated easily.

Power Testing

  • Position: Seated or standing.

  • Procedure: Ask the patient to flex the elbow with the forearm in supination against resistance.

  • Grading: Follow the Medical Research Council (MRC) scale (0–5).

Length Testing

  • Position: Patient supine.

  • Procedure: Extend the shoulder and elbow with the forearm in pronation.

  • A tight biceps will restrict full extension or cause anterior shoulder discomfort.

Therapeutic Exercises

1. Biceps Curls

  • Position: Standing or seated.

  • Procedure:

    • Hold a dumbbell with a supinated grip.

    • Flex the elbow, bringing the weight toward the shoulder.

    • Lower slowly.

  • Repetitions: 3 sets of 10–15 reps.

2. Isometric Biceps Hold

  • Position: Seated with elbow at 90° flexion.

  • Procedure:

    • Press against a stable object without changing elbow angle.

    • Hold for 10 seconds.

  • Repetitions: 5–10 holds per session.

3. Eccentric Biceps Loading (Post-injury rehab)

  • Position: Standing.

  • Procedure:

    • Use a heavier load for the lowering phase.

    • Assistance can be used for lifting.

    • Slowly lower the weight in 3–5 seconds.

Trigger Points of the Biceps Brachii

Common myofascial trigger points may develop in:

  • Mid-belly of the long head: Refers pain to the anterior shoulder.

  • Distal belly: Refers pain to the cubital fossa (anterior elbow).

Treatment:

  • Ischemic compression, dry needling, or myofascial release techniques.

  • Stretching and heat therapy can also reduce sensitivity.

Common Injuries Related to the Biceps Brachii

  1. Biceps Tendonitis

    • Common in athletes and manual workers.

    • Pain in the anterior shoulder, worsened with lifting or overhead activity.

  2. Biceps Tendon Rupture

    • May present with a “Popeye” deformity.

    • Loss of strength, especially in supination.

  3. Impingement Syndrome

    • Long head gets compressed under the acromion during shoulder elevation.

  4. Overuse Injuries

    • Repetitive lifting and pulling tasks can strain the muscle and tendon.

FAQs about the Biceps Brachii

Q1: Why is the biceps muscle important in daily life?
A: It enables vital movements such as lifting, pulling, and rotating the forearm. It also helps stabilize the shoulder during complex motions.

Q2: How can I tell if my biceps tendon is injured?
A: Symptoms include anterior shoulder pain, weakness in elbow flexion or supination, or a visible bulge in the upper arm after rupture.

Q3: What is the difference between the short and long head of the biceps?
A: The short head originates from the coracoid process and provides more stability to the shoulder, while the long head assists more in overhead motion and shoulder stability.

Q4: Can biceps exercises help in shoulder rehabilitation?
A: Yes, controlled strengthening of the biceps can enhance shoulder stability, especially after rotator cuff or labral injuries.

References


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