Dominic Stone
The biceps brachii, commonly known as the biceps, is a large, thick muscle on the upper arm's front portion. The biceps brachii is a two-joint muscle with two heads: a long head and a short head. The long head originates at the supraglenoid tubercle of the scapula, while the short head originates at the apex of the coracoid process of the scapula. The biceps brachii functions as a powerful supinator of the forearm, turning the palm upwards, and as a flexor of the forearm.
| Characteristics | Values |
|---|---|
| Common Name | Biceps |
| Scientific Name | Biceps Brachii |
| Type | Two-headed muscle |
| Location | Ventral portion of the upper arm |
| Function | Flexion and supination of the forearm |
| Innervation | Musculocutaneous nerve C5, C6, C7 |
| Blood Supply | Muscular branches of the brachial artery |
| Antagonist | Triceps Brachii |
| Origin | Scapula |
| Insertion | Radius |
| Joints | Shoulder, elbow, and radio-ulnar |
| Conditions | Popeye deformity, tendinitis, pulley lesions |
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What You'll Learn
The biceps brachii is a two-headed muscle
The biceps brachii is a large, thick muscle on the front of the upper arm between the shoulder and the elbow. It is commonly known simply as the biceps. The muscle is composed of two heads: the short head and the long head. The short head is sometimes referred to as "caput breve", while the long head is also called "caput longum". The long head is located on the lateral side of the biceps brachii, while the short head is located on the medial side.
The biceps brachii works across three joints and is able to generate movements in the glenohumeral, elbow, and radio-ulnar joints. In the shoulder joint, both muscle heads partially enforce opposite movements. The long head pulls the arm away from the trunk (abduction) and turns it inwards (inward rotation), while the short head pulls the arm back towards the trunk (adduction). When both heads contract simultaneously, it leads to an arm bend (flexion).
The biceps brachii also functions as a powerful supinator of the forearm, i.e. it turns the palm upwards. This action is aided by the supinator muscle and requires the humeroulnar joint of the elbow to be at least partially flexed. The biceps are a particularly powerful supinator due to their distal attachment at the radial tuberosity, on the opposite side of the bone from the supinator muscle.
The biceps brachii is supplied by the musculocutaneous nerve (C5-C7), a branch of the brachial plexus. The primary arterial blood supply for the biceps brachii comes from the muscular branches of the brachial artery.
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It is located on the upper arm
The biceps brachii is a large, thick muscle located on the upper arm. It is composed of two heads: the long head and the short head. The long head is located on the lateral side of the bicep brachii, while the short head is located on the medial side.
The biceps brachii is a two-joint muscle that acts on both the shoulder joint and the elbow joint. In the shoulder joint, the long head pulls the arm away from the trunk and turns it inwards, while the short head pulls the arm back towards the trunk. When both heads contract simultaneously, it leads to a bending of the arm.
In the elbow joint, the muscle bends the forearm and rotates it outwards. This outward rotation of the forearm is most powerful when the elbow is flexed. The biceps brachii is also involved in the supination of the forearm, which is the action of turning the palm upwards.
The biceps brachii is supplied by the musculocutaneous nerve, specifically the C5, C6, and C7 spinal roots. The primary arterial blood supply for the muscle comes from the brachial artery, with blood supplied by the muscular branches of the artery.
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The muscle's origin is at the scapula
The biceps brachii, or simply "biceps", is a large muscle that lies on the front of the upper arm between the shoulder and the elbow. The muscle is composed of two heads: the short head and the long head. The muscle derives its name from these two heads, which merge into one unique distal body. The short head originates from the apex of the coracoid process of the scapula, while the long head originates from the supraglenoid tubercle of the scapula. The supraglenoid tubercle is located above the glenoid cavity of the scapula, and the long head tendon exits the distal bicipital groove to join the short head tendon.
The biceps brachii is a two-joint muscle, and its origin at the scapula and insertion into the radius allow it to act on both the shoulder joint and the elbow joint. In the shoulder joint, the long head pulls the arm away from the trunk (abduction) and turns it inwards (inward rotation), while the short head pulls the arm back towards the trunk (adduction). When both heads contract simultaneously, it leads to a bend in the arm (flexion).
The biceps brachii is involved in several movements of the arm due to its ability to act on multiple joints. In the elbow joint, the muscle bends the forearm (flexion) and rotates it outwards (supination). The supination is most powerful when the elbow is flexed. The biceps also assist in forward flexion of the shoulder joint, bringing the arm forward and upwards.
The biceps brachii is supplied by the musculocutaneous nerve (C5-C7), a branch of the brachial plexus. The primary arterial blood supply for the muscle comes from the muscular branches of the brachial artery. The biceps brachii is a particularly powerful supinator of the forearm due to its distal attachment at the radial tuberosity. This attachment allows the biceps to effectively pull the radius back into its neutral supinated position.
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The biceps brachii functions as a forearm supinator
The biceps brachii is a large, thick muscle on the front of the upper arm between the shoulder and the elbow. It is one of the chief muscles of the arm and is also referred to simply as the biceps. The biceps brachii has two heads, the short head and the long head, which originate at the coracoid process and supraglenoid tubercle of the scapula, respectively. The two heads unite to form a single muscle belly, which is attached to the upper forearm.
The biceps brachii is a two-joint muscle, acting on both the shoulder joint and the elbow joint. In the shoulder joint, the long head pulls the arm away from the trunk (abduction) and turns it inwards (inward rotation), while the short head pulls the arm back towards the trunk (adduction). When both heads contract simultaneously, it leads to an arm bend (flexion).
In the elbow joint, the biceps brachii bends the forearm (flexion) and rotates it outwards (supination). This outward rotation is facilitated by the 90-degree rotation of the muscle as it connects to the radius. The supination is most powerful when the elbow is flexed, and this movement is used when opening a bottle with a corkscrew.
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It is supplied by the musculocutaneous nerve
The biceps brachii muscle, commonly known as the biceps, is a large, thick muscle on the upper arm's ventral portion. The muscle is composed of a short head and a long head. The biceps brachii works across three joints and is able to generate movements in the glenohumeral, elbow, and radio-ulnar joints.
The biceps brachii is supplied by the musculocutaneous nerve, a major peripheral nerve of the upper limb. The nerve arises from the C5, C6, and C7 spinal roots and is a terminal branch of the brachial plexus' lateral cord. It runs from the inferior border of the pectoralis minor, pierces the coracobrachialis, and traverses distally between the biceps and brachialis.
The musculocutaneous nerve provides sensory and motor innervation to the biceps brachii and other muscles in the anterior compartment of the arm, including the coracobrachialis and brachialis. It also provides sensory innervation to the lateral aspect of the forearm through its terminal branch, the lateral cutaneous nerve.
The musculocutaneous nerve plays an important role in the function of the biceps brachii, facilitating movements such as flexion and supination of the forearm. However, overuse of the biceps brachii and associated muscles can lead to stretching or compression of the musculocutaneous nerve, resulting in symptoms like pain, tingling, or reduced sensation in the lateral side of the forearm.
In summary, the biceps brachii is a significant muscle in the upper arm, and its function and health are closely linked to the musculocutaneous nerve, which provides sensory and motor innervation, enabling various movements and sensations in the arm and forearm.
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Frequently asked questions
The biceps brachii, or biceps, is a large muscle that lies on the front of the upper arm between the shoulder and the elbow.
The main functions of the biceps are the flexion and supination (outward rotation) of the forearm. It also assists in forward flexion of the shoulder joint.
The biceps brachii is a two-joint muscle with two heads that merge into one muscle belly, which attaches to the forearm. The long head originates at the supraglenoid tubercle of the scapula, and the short head originates from the coracoid process of the scapula.
