What are biceps?
Biceps muscles are any group of muscles in the body that have two heads or points of origin. In humans, the two main biceps in the body are biceps brachii and biceps femoris. The first includes the large muscle on the front side of the upper arm, which is involved in the pulling in of the forearm toward the elbow. Another bicep (femoris) pulls the thigh near the trunk. The biceps muscle consists of two heads and a muscle belly. The muscle belly is attached to the bones with the help of tendons (muscle head). When the belly contracts, it pulls the forearm (or thigh) up and rotates it outward. It also helps transmit forces produced by the muscle belly to control the movement of the leg at the knee joint.
Basic anatomy of biceps brachii
The biceps brachii is one of the chief muscles located in the front (anterior) compartment of the arm. It is a large muscle that lies on the front of the upper arm between the shoulder and the elbow. It works across three joints and is able to generate movements of the shoulder and elbow. The muscle consists of a short head and a long head distinguished according to their origin at the coracoid process and winged-shaped bone in the upper back forming part of the shoulder joint (supraglenoid tubercle of the scapula). Both heads of the biceps join in the middle upper arm to form a common muscle belly. As the muscle extends distally, the two heads rotate 90 degrees and join to attach to the radius (bone in the forearm) as biceps tendon.
Functions of biceps brachii
Biceps brachii is a double-headed muscle that has two points of origin. It is a bi-articular muscle that helps control the motion of shoulder and elbow joints. The primary function of the muscle is flexion of the elbow and turning of the forearm (supination). The function of the biceps at the elbow is essential for the function of the forearm in lifting and pulling. The function at the shoulder is less pronounced playing minor roles in moving the arms forward, upward and sideways. Biceps brachii is one of the most variable muscles and is possible to have three to seven heads originating at the bone of the upper arm (humerus). The size of biceps brachii is a conventional symbol of bodily strength. Exercise can improve the tone and appearance and increase the size of the biceps brachii.
Basic anatomy of biceps femoris
It is a long muscle of the back compartment (posterior) of the thigh. It has a long and short head originating from the ischium and hip bone, respectively. The long head forms the part of the hamstrings muscle group and occupies the posterior section of the thigh. The two muscle heads join together away from the head and unite in an intricate fashion. The short head of the biceps femoris joins the belly of the long head in its deep surface as it descends in the thigh.
Functions of biceps femoris
These muscles provide bending (flexion) at the knee and extension at the hip when they contract. When the thigh is flexed, the hamstring muscles help tilt the pelvis backward. The muscle is important for knee flexion, internal and external rotation and hip extension. Tight hamstrings sometimes are associated with lower back pain. This muscle can be used to administer intramuscular injections. Overuse of the muscle could result in tearing of the muscles and ligaments.
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