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The biceps brachii, commonly known as the biceps, is a large, thick muscle on the front of the upper arm. It is one of the chief muscles of the arm and is involved in the flexion and outward rotation of the forearm. The biceps is located between the shoulder and the elbow and is attached to these joints by tendons. It is composed of a short head and a long head, which originate from the scapula (shoulder blade) and combine in the middle arm to form a muscle mass. The other end of the biceps attaches to the radius, one of the two bones that make up the forearm.
| Characteristics | Values |
|---|---|
| Common name | Biceps |
| Latin name | Biceps Brachii |
| Meaning | Two-headed muscle of the arm |
| Muscle structure | Consists of two heads, a short head and a long head |
| Muscle location | Front of the upper arm between the shoulder and the elbow |
| Muscle function | Flexion and supination (outward rotation) of the forearm |
| Muscle movement | Bends the forearm and rotates it outwards |
| Muscle supply | Musculocutaneous nerve (C5-C6) |
| Muscle nerve roots | C5 and C6 |
| Muscle blood supply | Muscular branches of the brachial artery |
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What You'll Learn
The biceps brachii muscle is located in the upper arm
The biceps brachii muscle, commonly known simply as the biceps, is a large, thick muscle on the upper arm's ventral portion. The muscle is composed of two heads: the short head and the long head. The long head is located on the lateral side of the biceps brachii, while the short head is located on the medial side. The long head of the biceps brachii tendon originates at the supraglenoid tubercle and superior glenoid labrum, with an average tendon length of 9 cm. The short head originates from the apex of the coracoid process of the scapula.
The biceps brachii is one of the chief muscles of the arm, and its name derives from its two heads, which merge into one unique distal body. This unusual structure allows the biceps to act on both the shoulder joint and the elbow joint. The muscle's primary function is to flex the elbow and rotate the forearm, with the long head pulling the arm away from the trunk and turning it inwards, and the short head pulling the arm back towards the trunk. When both heads contract simultaneously, it leads to an arm bend.
The biceps brachii is supplied by the musculocutaneous nerve, a branch of the brachial plexus. The primary arterial blood supply for the biceps brachii comes from the muscular branches of the brachial artery, with the artery providing blood supply originating from up to eight vessels. The musculocutaneous nerve provides sensory and motor innervation for the biceps, arising from the C5 and C6 spinal roots.
The biceps brachii is an important landmark for locating the brachial artery during physical examinations. It provides an orientation for the palpation of the brachial artery, which is palpated deep to the biceps. The biceps reflex is tested by striking the insertion tendon with a hammer, activating a contraction of the muscle.
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It is attached to the shoulder and elbow joints
The biceps brachii, or simply "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 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.
The biceps muscle is attached to the bones of the shoulder and elbow by tendons, which are strong cords of fibrous tissue that attach muscles to bones. The biceps tendon at the elbow is called the distal biceps tendon, and it attaches to a part of the radius bone called the radial tuberosity, a small bump on the bone near the elbow joint. The radial tuberosity is a confluent muscle belly formed by the combination of the two heads of the biceps muscle in the middle arm. The radial tuberosity then continues as the bicipital aponeurosis, crossing the elbow joint to insert into the radius and forearm fascia.
The long head of the biceps brachii tendon originates at the supraglenoid tubercle and superior glenoid labrum, which is above the glenoid cavity of the scapula. The long head tendon exits the distal bicipital groove and joins the short head tendon. The long head tendon is a well-recognized source of anterior shoulder pain, and it is vulnerable to tenosynovial inflammation due to its association with the glenohumeral joint's synovial lining.
The short head of the biceps brachii originates at the apex of the coracoid process of the scapula, where it partly blends with the origin tendon of the coracobrachialis. The short head is sometimes referred to as "caput breve", while the long head is also called "caput longum". The biceps muscle helps to bend and rotate the arm. 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 muscle bends the forearm (flexion) and rotates it outwards (supination).
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The biceps has two heads: a short and a long head
The biceps brachii, or simply "biceps", is a large, thick muscle on the upper arm's ventral portion. The muscle is composed of two heads: a short head and a long head. The short head is sometimes referred to as "caput breve", while the long head is also called "caput longum".
The short head originates from the apex of the coracoid process of the scapula (shoulder blade). The long head originates from the supraglenoid tubercle of the scapula, above the glenoid cavity. The long head's labral origin is mostly posterior in most individuals, while the tendon is 9 cm long on average. The long head tendon possesses a rich sympathetic nerve network.
The two heads merge in one unique distal body, defining the unusual structure of the muscle. They unite to form a confluent muscle belly before tapering across the anterior aspect of the elbow, inserting on the radius and forearm fascia. The biceps brachii continues as the bicipital aponeurosis, crossing the elbow joint.
The biceps has several functions. It is involved in the flexion and supination (outward rotation) of the forearm. 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 muscle bends the forearm (flexion) and rotates it outwards (supination).
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The long head is located on the lateral side, and the short head on the medial side
The biceps brachii, or simply "biceps", is a large, thick muscle on the upper arm's ventral portion. The biceps brachii muscle is one of the chief muscles of the arm. The name 'biceps' comes from its two heads, which merge into one unique distal body. These two heads are the short head and the long head.
The long head is located on the lateral side of the biceps brachii, while the short head is located on the medial side. The short head originates from the apex of the coracoid process of the scapula. The long head originates from the supraglenoid tubercle of the scapula, above the glenoid cavity. The long head's labral origin is mostly posterior in most individuals. The tendon is 9 cm long on average.
The biceps brachii works across three joints and is able to generate movements in the glenohumeral, elbow, and radio-ulnar joints. The main functions of the biceps are the flexion and supination (outward rotation) of the forearm. This is facilitated by the 90-degree rotation of the muscle as it connects to the radius. 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 an arm bend.
The biceps are susceptible to various conditions and injuries. For example, the "popeye deformity", common to baseball pitchers, arises from a ruptured long head tendon due to chronic wear and tear. This causes the muscle to form a ball at the anterior mid-arm. The long head of the biceps tendon is also a well-known source of anterior shoulder pain. Mechanical causes include repetitive traction, friction, and glenohumeral rotation.
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The biceps is involved in the flexion and supination of the forearm
The biceps muscle is located in the front of the upper arm between the shoulder and the elbow. It is a long, thick muscle that is easily flexed and visible when contracted. The bicep's primary function is to flex the forearm and supinate the forearm, and it is involved in a variety of movements at the shoulder and elbow joints.
When the biceps contract, it pulls on the radius bone in the forearm, bringing the hand and wrist forward in a flexion movement. This action is crucial for many everyday tasks such as lifting objects towards the chest, and it is also important in sports such as climbing and swimming. The degree of flexion possible at the elbow is considerable, with a full range of motion from a straight arm to a fully flexed position.
The biceps are also involved in supination, which is the action of turning the palm of the hand upwards. This movement is also facilitated by the biceps tendon attaching to the radius bone, and it allows for a wide range of rotational movements in the forearm. Supination is important for actions such as turning a door handle or screwdriver, and it is also key to many sports such as tennis and golf, where the forearm rotates during the action of serving or swinging.
The muscle's ability to supinate and flex the forearm is aided by its two heads, which originate at different points on the scapula (shoulder blade). This allows for a greater range of motion and the ability to perform complex movements with precision and strength. The short head of the biceps, which is the lower part of the muscle, is particularly important for supination, while the long head is more involved in flexion movements.
In addition to its role in forearm movement, the biceps also contribute to stabilization and movement at the shoulder joint. It assists in shoulder flexion, where the arm is raised forward and upward, and it also helps with abduction, where the arm is lifted out to the side. The biceps work in conjunction with other muscles in these movements, including the deltoids and coracobrachialis, to provide a full range of motion and stability.
Overall, the biceps play a crucial role in forearm flexion and supination, as well as contributing to movement and stability at the shoulder joint. Its ability to contract strongly and visibly has also given it a cultural significance, with well-developed biceps often associated with strength and health. Understanding the function and anatomy of the biceps is important for anyone wishing to improve their upper body strength and for those studying movement and anatomy in a medical or sports context.
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Frequently asked questions
The biceps muscle is located in the front of the upper arm, between the shoulder and elbow joints.
The biceps brachii muscle originates at the scapula and inserts into the radius of the forearm.
The biceps muscle's main functions are the flexion and supination (outward rotation) of the forearm.
Common conditions affecting the biceps include tendon tears, tendinitis, and tenosynovial inflammation, often caused by physical trauma, overuse, or repetitive activity.
