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The biceps brachii is a large muscle that lies 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 composed of two heads, the short head and the long head. The biceps shares its nerve supply with the brachialis and coracobrachialis muscles, which lie underneath the biceps. The biceps tendon is attached to the inner protrusion near the head of the radius, a bone in the forearm. This muscle is a forearm flexor when extended and becomes the forearm's most powerful supinator when flexed.
| Characteristics | Values |
|---|---|
| Muscle name | Biceps brachii |
| Muscle type | Two-headed muscle |
| Muscle location | Upper arm |
| Muscle function | Supination and flexion of the forearm |
| Muscle attachments | Origin at the scapula, insertion into the radius |
| Muscle innervation | Musculocutaneous nerve (C5-C6) |
| Blood supply | Brachial artery |
| Muscle stabilization | Supports and stabilizes the brachialis muscle |
| Muscle compartments | Anterior and posterior compartments |
| Associated muscles | Brachialis, coracobrachialis, triceps brachii |
| Tendon connections | Two tendons attach to the bone at the shoulder |
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What You'll Learn
The biceps brachii is a two-headed muscle
The biceps brachii is one of the chief muscles of the arm, with its origin at the scapula and insertion into the radius, allowing it to act on both the shoulder and elbow joints. It is involved in movements such as supination of the forearm, flexion of the arm at the elbow and shoulder, and abduction and adduction of the arm. The biceps brachii shares its nerve supply with the brachialis and coracobrachialis muscles, and it is supplied by the musculocutaneous nerve. The blood supply to the biceps brachii is the brachial artery.
The biceps brachii is located superficially to the brachialis and coracobrachialis muscles, forming the anterior side of the arm. Its insertion tendon can be easily observed and palpated at the crook of the arm. The medial and lateral bicipital grooves are formed by the space between the biceps and triceps, and they contain important structures such as the brachial artery and nerves. The biceps brachii is a two-joint muscle, with its long and short heads performing different functions in the shoulder and elbow joints.
The long head of the biceps brachii has a significant role in preventing the upward displacement of the head of the humerus. Additionally, it pulls the arm away from the trunk (abduction) and turns it inwards (inward rotation). On the other hand, the short head pulls the arm back towards the trunk (adduction). When both heads contract simultaneously, it results in an arm bend (flexion).
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The coracobrachialis muscle lies underneath the bicep
The biceps brachii is a two-headed muscle that lies on the front of the upper arm between the shoulder and the elbow. It is one of three muscles in the anterior compartment of the upper arm, along with the brachialis and the coracobrachialis muscle. The coracobrachialis muscle lies underneath the bicep, deep to the biceps brachii in the arm. It is a slender muscle that originates from the deep surface of the coracoid process of the scapula. The muscle fibres run inferolaterally towards the humerus and insert onto the anteromedial surface of the humeral shaft, between the brachialis muscle and the medial head of the triceps.
The coracobrachialis muscle is located medial to the biceps brachii and brachialis muscles. It is situated at the superomedial part of the humerus. The apex of the coracoid process is located between the pectoralis minor and the short head of the biceps brachii muscle. The tendon of the coracobrachialis attaches to the linear impression at the medial side of the midshaft of the humerus.
The coracobrachialis muscle shares its nerve supply with the biceps and brachialis muscles. It is perforated by and innervated by the musculocutaneous nerve, which arises from the anterior division of the upper trunk (C5, C6) and middle trunk (C7) of the brachial plexus. The musculocutaneous nerve is made up of fibres from the fifth, sixth and seventh cervical nerves. The brachial artery supplies the blood to the biceps, and the coracobrachialis receives its blood supply by a branch of the brachial artery.
Overuse of the coracobrachialis can lead to a hardening or stiffening of the muscle. This can be caused by heavy weightlifting or gymnastics. Symptoms include pain in the arm and shoulder, radiating down to the back of the hand. In more severe cases, the musculocutaneous nerve can become trapped, causing disturbances in sensation to the skin on the forearm and weakened flexion of the elbow.
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The brachialis muscle is deep to the bicep
The biceps brachii is a two-headed muscle that sits 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 the most prominent muscle of the upper arm. The biceps brachii is also one of three muscles in the anterior compartment of the upper arm, along with the brachialis and coracobrachialis muscles. The brachialis muscle is deep to the biceps brachii and is found more distally than the other muscles of the arm. It forms the floor of the cubital fossa.
The biceps brachii is a large, thick muscle consisting of two heads: the long head and the 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. Both heads of the muscle arise on the scapula and join to form a single muscle belly, which is attached to the upper forearm. The biceps brachii muscle is supplied by the musculocutaneous nerve (C5-C6), a branch of the brachial plexus. The blood supply to the biceps is provided by the brachial artery.
The brachialis muscle, on the other hand, originates from the medial and lateral surfaces of the humeral shaft and inserts into the ulnar tuberosity, just distal to the elbow joint. It is innervated by the musculocutaneous nerve, with contributions from the radial nerve. The brachialis muscle is the strongest flexor of the elbow in the absence of supination. With supination and flexion, its mechanical momentum becomes less advantageous than the biceps brachii.
The biceps and brachialis muscles work together to flex the elbow. The biceps brachii is the most prominent muscle of the upper arm, but it primarily serves to support and stabilise the deeper and stronger brachialis muscle whenever the forearm is lifted or lowered. The biceps brachii also plays a role in shoulder flexion, although this role is more limited to the initial 30 degrees of elevation.
The biceps brachii and brachialis muscles arise from a common premuscular mass. They are distinguished by the fact that the biceps brachii has two heads that merge in a unique distal body, defining its unusual structure.
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The bicep's main function is to supinate the forearm
The biceps brachii is a large muscle that lies on the front of the upper arm between the shoulder and the elbow. It is traditionally described as a two-headed muscle, with a short head and a long head, but some anatomical variations have been observed. The biceps' main function is to supinate the forearm, or in other words, to turn the palm upwards. This movement is possible due to the distal attachment of the muscle at the radial tuberosity, on the opposite side of the bone from the supinator muscle.
The long head of the biceps originates at the supraglenoid tubercle of the scapula, while the short head originates at the apex of the coracoid process of the scapula. Both heads join in the middle upper arm to form a single muscle belly, usually near the insertion of the deltoid. As the muscle extends distally, the two heads rotate 90 degrees externally before inserting onto the radial tuberosity. This 90-degree rotation facilitates the supination of the forearm.
The biceps brachii is one of the chief muscles of the arm and is involved in several important functions. It is one of three muscles in the anterior compartment of the upper arm, along with the brachialis muscle and the coracobrachialis muscle. These three muscles share a nerve supply from the musculocutaneous nerve. The biceps also work across three joints, with its most important function being the supination of the forearm and flexion of the elbow.
The biceps brachii is a powerful supinator of the forearm, especially when the limb is pronated. This function is aided by the supinator muscle, and it requires the elbow to be at least partially flexed. The supination movement of the biceps is used in everyday tasks such as opening a bottle with a corkscrew. This action involves first screwing in the cork (supination) and then pulling the cork out (flexion).
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The bicep is the most prominent muscle of the upper arm
The biceps brachii, or simply "biceps", is a large, thick muscle of the upper arm. It is located on the front of the upper arm, between the shoulder and the elbow. The biceps is one of four muscles in the upper arm, with three in the anterior compartment (biceps brachii, brachialis, coracobrachialis) and one in the posterior compartment (triceps brachii).
The biceps is the most prominent muscle of the upper arm, but it primarily serves to support and stabilise the deeper and stronger brachialis muscle whenever the forearm is lifted or lowered. The biceps muscle has two heads, the short head and the long head, which arise on the scapula and join to form a single muscle belly attached to the upper forearm. The long head of the biceps crosses both the shoulder and elbow joints, but its main function is at the elbow, where it flexes and supinates the forearm.
The short head of the biceps originates at the apex of the coracoid process of the scapula, where it partly blends with the origin tendon of the coracobrachialis. The long head originates from the supraglenoid tubercle of the scapula. Both heads insert distally into the radial tuberosity and the fascia of the forearm via the bicipital aponeurosis. The biceps tendon reflex tests spinal cord segment C6.
The biceps shares its nerve supply with the other two muscles of the anterior compartment, which are supplied by the musculocutaneous nerve. Fibres of the fifth, sixth and seventh cervical nerves make up the components of the musculocutaneous nerve that supplies the biceps. The blood supply of the biceps is the brachial artery. The distal tendon of the biceps can be useful for palpating the brachial pulse, as the artery runs medial to the tendon in the cubital fossa.
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Frequently asked questions
The biceps brachii lies superficial to the brachialis and coracobrachialis muscles. The brachialis muscle is the strongest flexor of the elbow.
The biceps' main function is to supinate the forearm and flex the elbow. It also flexes the arm at the shoulder.
The biceps brachii is a two-headed muscle of the arm. It is one of the chief muscles of the arm.
The biceps brachii originates at the supraglenoid tubercle above the glenoid cavity of the scapula.
The biceps brachii inserts on the radius and forearm fascia.
