Dominic Stone
The biceps is a large muscle that lies on the front of the upper arm between the shoulder and the elbow. The biceps muscle is made up of two heads, with tendons that anchor the muscles to bone. The long head originates from a cavity in the scapula and passes through the shoulder joint to the upper arm. The short head originates from a projection on the scapula and runs alongside the long head on the inside of the arm. The two heads join in the middle arm to form a combined muscle belly. The biceps brachii is one of the chief muscles located in the front (anterior) compartment of the arm. It is involved in the pulling in of the forearm toward the elbow.
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What You'll Learn
The biceps brachii is a two-headed muscle
The long head of the biceps brachii originates from a cavity in the scapula called the glenoid and passes through the shoulder joint to the upper arm through a groove in the humerus (the large bone of the upper arm). It remains tendinous as it passes through the shoulder joint and through the intertubercular groove of the humerus. The short head of the biceps brachii, on the other hand, originates from a projection on the scapula called the coracoid and runs alongside the long head on the inside of the arm. The coracoid process is a protrusion of the scapula.
The two heads of the biceps brachii unite to form a single muscle belly at the anterior side of the humerus and attach to the radial tuberosity. The radial tuberosity is a rough projection just beneath the neck of the radius, a bone of the forearm. The biceps brachii is the only muscle that crosses two joints: the elbow joint and the glenohumeral (shoulder) joint.
The biceps brachii has several functions, including 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 biceps femoris is a hamstring muscle
The biceps femoris has two heads, a short head and a long head, that originate from different locations but share the same insertion site. The long head originates from the medial facet (inferomedial impression) of the ischial tuberosity, which is a rounded portion of the pelvic bone. The short head originates from the lateral lip of the inferior third of the linea aspera and the supracondylar ridge of the femur (thighbone). The tendon of the long head of the biceps femoris shares a tendon with the semitendinosus muscle and the sacrotuberous ligament. The tendons of the biceps femoris and semitendinosus run together before separating into two distinct muscles.
The biceps femoris muscle has several important functions. At the hip joint, it produces the movement of hip extension, which is strongest when the trunk is brought from a forward bend to an upright position. It also assists with external rotation when the hip joint is in an extended position. At the knee joint, the most prominent action of the biceps femoris is flexion of the leg, which occurs when the lower limb is in an anatomical position. When the knee is semiflexed, the biceps femoris acts to produce external rotation of the leg at the knee.
The biceps femoris, along with the other hamstring muscles, plays a crucial role in stabilising the pelvis, especially during the forward flexion of the trunk. It is involved in many leg movements, including walking, climbing stairs, and performing squats. However, hamstring muscles are also prone to injuries, especially in athletes who engage in activities that require quick stops and starts, such as soccer, football, skiing, and dancing.
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Biceps are involved in forearm flexion
The biceps is a large muscle that lies on the front of the upper arm between the shoulder and the elbow. It is called a
The biceps muscle is comprised of two heads. At each end are connective tissues called tendons that anchor the muscles to bone. The long head originates from a cavity in the scapula called the glenoid. It passes through the shoulder joint to the upper arm through a groove in the humerus (the large bone of the upper arm). The short head originates from a projection on the scapula called the coracoid and runs alongside the long head on the inside of the arm. The two heads join in the middle arm to form a combined muscle belly. Although the heads work in tandem to move the forearm, they are anatomically distinct, with no conjoined fibres.
The biceps brachii is a prominent muscle on the front side of the upper arm. It bends the forearm towards the upper arm and is thus used in lifting and pulling movements. It also supinates the forearm (turns the palm forward or upward). The size of the biceps brachii is a conventional symbol of bodily strength.
The biceps brachii is one of the most variable muscles in the human body. It has a third head arising from the humerus in 10% of cases, most commonly originating near the insertion of the coracobrachialis and joining the short head. However, four, five, and even seven supernumerary heads have been reported in rare cases.
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Biceps brachii tears are common in athletes
The biceps brachii is a large muscle that lies on the front of the upper arm between the shoulder and the elbow. It is involved in the flexion and outward rotation of the forearm. The biceps brachii is made up of two heads, which originate in two places: the coracoid process, a protrusion of the scapula (shoulder blade), and the upper glenoid cavity, the hollow for the shoulder joint. The two heads join in the middle of the upper arm to form a single muscle belly. The biceps brachii is one of the most variable muscles in the human body, with a third head arising from the humerus in 10% of cases.
Biceps brachii tears are a common injury among athletes. They can be caused by a sudden injury, especially eccentric loading or muscle resistance against lengthening. They can also result from forceful, eccentric contraction of the biceps muscle while lifting. Tears can be either partial or complete. Partial tears damage the soft tissue but do not completely sever the tendon, and the torn muscle fibres do grow back as healing takes place. Complete tears, on the other hand, completely detach the tendon from the bone, and the tendon is no longer intact.
Athletes who participate in sports with repeated overhead motions are particularly at risk of developing biceps tears. Baseball players, tennis players, golfers, and swimmers are especially susceptible. Tears can also occur as a result of the aging process, as tendons start to wear down and fray over time. This process can be accelerated by overuse, with repeated shoulder motions causing further wear and tear.
Treatment for a biceps tear will depend on the severity of the injury. In many cases, the muscle will heal over time without the need for surgery. Applying cold pressure and using anti-inflammatory medications can help to manage pain and reduce swelling. More severe tears may require surgery and post-operative physical therapy to restore strength and functionality to the muscle. Surgery is typically reserved for elite athletes who require a complete recovery.
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The biceps shares its nerve supply with other muscles
The biceps brachii muscle is a large, thick muscle in the anterior compartment of the upper arm. It is one of the chief muscles of the arm and is involved in several movements of the arm. The biceps brachii muscle is a two-headed muscle, with a third head arising from the humerus in 10% of cases. The two heads are the short head and the long head, which are distinguished according to their origin at the coracoid process and supraglenoid tubercle of the scapula, respectively.
The biceps shares its nerve supply with the other two muscles of the anterior compartment of the upper arm, the brachialis muscle and the coracobrachialis muscle. The nerve that supplies these three muscles is called the musculocutaneous nerve, which is derived from cervical spinal nerves C5-C7. The musculocutaneous nerve provides motor innervation to the muscles of the anterior compartment of the arm and sensory innervation to the lateral forearm. It courses through the anterior part of the arm, terminating 2 cm above the elbow.
The musculocutaneous nerve gives rise to the lateral cutaneous nerve of the forearm, which initially enters the deep forearm but then pierces the deep fascia to become subcutaneous. In this region, it can be found close to the cephalic vein. The lateral cutaneous nerve of the forearm innervates the skin of the anterolateral aspect of the forearm. The musculocutaneous nerve also gives articular branches to the elbow joint and the humerus.
The biceps brachii muscle is supplied by the musculocutaneous nerve (C5-C6), a branch of the brachial plexus. The musculocutaneous nerve descends between the brachialis and biceps brachii muscles, sending branches to innervate them. The nerve then pierces the deep fascia lateral to the biceps brachii and continues into the forearm as the lateral cutaneous nerve, providing sensory innervation to the lateral aspect of the forearm.
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Frequently asked questions
The biceps brachii is a large muscle that lies on the front of the upper arm between the shoulder and the elbow. It is involved in the pulling in of the forearm toward the elbow.
The biceps brachii consists of two heads, the short head and the long head, which originate at the coracoid process and supraglenoid tubercle of the scapula, respectively.
The main function of the biceps brachii is to supinate the forearm and flex the elbow. It also helps to control the motion of the shoulder and elbow joints.
The long head of the biceps brachii crosses both the shoulder and elbow joints, while the short head originates from a projection on the scapula called the coracoid and runs alongside the long head on the inside of the arm.
The biceps brachii can be strengthened using weight and resistance training. Examples of exercises that target this muscle include the chin-up and biceps curl.
