The biceps refers to the biceps brachii muscle. It is found in humans in the upper arm, but is also found in quadruped mammals (such as dogs). In both cases he is responsible, inter alia, for bending the arm or foreleg.

What characterizes the biceps brachii muscle?

The upper arm muscle, often referred to as the "two-headed muscle of the arm" or "biceps" for short, is a skeletal muscle that consists of two muscle heads. He is located on the upper or front of the upper arm and is responsible for bending the arm. For this reason, he is also called "Armbeuger". Basically, the two-headed Schenkelbeuger muscle is referred to as biceps. However, the term is more common in the humeral muscle than in the biceps femoris muscle .

Anatomy & Construction

Under the two-headed muscle of the arm the medicine understands a skeletal muscle, which is in the upper arm. The biceps brachii muscle consists of two muscle heads: the long head ( Caput longum ) and the short head (also known as the short head). These two heads are responsible for the naming of the muscle. They arise in humans from the shoulder blade. The two heads of the biceps connect approximately where they are visible from the outside. Here they become a single muscle body or muscle belly. This muscle belly sets below the elbow, directly at the muscle tuber called Tuberositas radii of the spoke (medically called radius), together with a tendon of the upper arm. This tendon branches into the aponeurosis musculi bicipitis (sinewy muscle origin) and into the fascia of the forearm (the fascia antebrachii ). Unlike humans, the biceps of four-legged mammals such as dogs, cats, and horses have only one origin at the small bony tubercle ( tuberculum supraglenoidale ) of the scapula. As a result, the biceps also has only one head in this case. From a comparative anatomical point of view, however, he is still dubbed in medicine as a bisexual and thus as a biceps.

Function & Tasks

The bicep is responsible for turning the forearm out of its home position so that the thumb rotates from the inside to the outside and around the hand until it points vertically upwards and in the opposite direction of the home position. Anatomy speaks of supination in this function. If the forearm is already in a supinated position, the bicep will be able to return it to its original position. Another task of the biceps is to flex the forearm in the elbow area.

Both heads have their own tasks, which in detail affect the entire function of the biceps. The long head is stressed when the upper arm is lifted or removed from the rib cage. The short head is responsible for movements in which the arm is to be guided towards the chest.

In addition, both muscle heads act simultaneously on the movement process when the arm is to be guided away from the body and forward. The two heads are also necessary for the internal rotation of the arm. Here they work together, creating a smooth movement. In addition, they also ensure that the arm is not turned too far. As a result, they prevent injuries.

A difference in function is found in the biceps again in the comparison between humans and animals - in four-legged mammals, the biceps acts as a connection of the leg to the shoulder joint and operates exclusively as a flexor of the elbow. Rotary movements are not common in animals such as dogs, cats and horses and are therefore not intended. For this reason, the biceps are less strong and strong in them. He is also slightly weaker than the human biceps or other bipedal mammals.

Diseases & complaints

The most common condition associated with the biceps is biceps tendon rupture in humans. In this rupture, the tendon or tendon of the muscle is usually torn. Another and similar injury can be a muscle strain. In most cases, both injuries are caused by trauma, as it can happen through an accident.

A rupture or straining of the biceps can also be caused by a short or long-term overload of the upper arm. In the elderly, a rupture or strain of the muscle often occurs as a result of age-related wear. The muscle often weakens with age and thus more susceptible to injury.

A disease of the biceps, however, is a pulley lesion. Such is the case of medicine when there is an unnatural displacement of the tendon of origin. Such a lesion usually occurs when the tendon shifts in the course of time obliquely in the groove of the shoulder joint. This can happen, inter alia, by an overload, but also by an accident.

In rare cases, the tendon is already offset at birth. Relocation of the tendon over time causes it to thinn out and is therefore more prone to injury. Often, the pulley lesion ends in biceps tendon fracture. For this reason, the medicine also speaks of such a comprehensive, if there is a displacement-related injury to the tendon.

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