BICEPS BRACHII: ORIGIN AND INSERTION, FUNCTIONS, PATHOLOGIES - ANATOMY AND PHYSIOLOGY - 2025

The biceps brachii is a large muscle located in the anterior area of ​​the upper limb, seen clearly under the skin and which has been revered by human culture as a symbol of strength and body beauty.

The biceps brachii muscle, together with the more deeply located and smaller anterior brachialis muscle, make up the group of flexor muscles of the upper limb, acting on the elbow joint and its surroundings.

From the Latin biceps brachii, it owes its name to the presence of two "heads" in its origin, remembering that the prefix "bi" means "double" and "ceps" refers to "heads" or "portions".

The biceps brachii is nourished thanks to the vascularization provided by one or sometimes two direct branches of the main artery of the arm, the humeral, known by the name of bicipital arteries, and its motor and sensory innervation depends on a branch from the musculocutaneous nerve directly: the biceps nerve.

Origin and insertion

As previously mentioned, it is made up of two portions or heads proximal to the shoulder:

Short or short portion

It begins in the process or coracoid process of the scapula.

Long portion

It begins in the supraglenoid tubercle of the scapula by a long tendon, crosses the humeral joint and sits in the intertubercular groove of the humerus.

Both portions, joining, continue in an elongated belly that ends in a common tendon that attaches to the bicipital tuberosity of the radius.

Features

The biceps flexes the forearm at the elbow joint. Thanks to its insertion in the radius, it also acts as a supinator, producing a rotary movement if the forearm has previously performed the pronation with opposite rotation.

Pathology

Biceps injuries can appear from either of its two origins, in its course or in the region of the elbow where it inserts and ends.

Various factors influence the appearance of diseases in the biceps, many related to physical activities - sports or work - or age.

Among the most frequent pathologies of the biceps brachii we have:

Bicipital tendinitis

Although the name assumes that the pathology encompasses the entire muscle, it actually refers to the long portion or head of the muscle and is associated with other shoulder injuries such as those of the rotator cuff.

It usually occurs as a consequence of a repetitive action of the shoulder, as occurs in some work or sports activities, and its diagnosis and treatment are delayed because initially the discomfort is tolerable.

Those who suffer from tendonitis or bicipital instability present with pain of varying intensity in the anterior region of the shoulder that can extend to the arm and worsens with activities that put pressure on the shoulder.

A particular sign of bicipital instability is a popping or clicking sound that is heard or felt when the shoulder is moved or rotated.

Biceps tendon rupture is characterized by the appearance of sudden and intense pain, either at the shoulder or elbow level, with a tearing sensation referred to by patients as if something had broken inside. It is accompanied by local swelling, bruising, weakness, and difficulty moving the affected arm.

Instability of the long head of the biceps

It is produced by the tendon leaving its usual route, which is the intertubercular groove of the humerus, also known as the bicipital groove of the shoulder.

Overuse and trauma are the main causes of this instability, although it can also be found in the elderly due to weakening of the tendon and muscle fibers.

Biceps tendon tear

It can affect either of the two heads of the biceps:

Proximal

The injury can be partial or complete and begins in an already weakened tendon, which can definitively rupture after great effort when lifting weight.

The long head of the biceps is injured more frequently, however the damage of the short head is unusual, so that being healthy, the person can continue to use the shoulder although with pain.

The damage can be traumatic in origin, as occurs when trying to stop a fall with the arm fully extended, or from wear and tear on an overused tendon, which is more prone to injury.

The risk of injury increases with age, certain sports such as tennis, swimming or weightlifting, and heavy work activities.

Distal

Less frequent than the previous one but more dramatic. It presents as the avulsion or complete tear of the insertion of the tendon in the elbow, specifically in the bicipital tuberosity of the radius.

It occurs when the flexed elbow is forced to extend violently, such as when dropping a heavy box or trying to catch a free falling load.

Diagnosis and treatment

In addition to the symptomatic clinic, which is quite characteristic, complementary studies such as radiographs, echo sonograms of soft tissues and more specifically MRI of the affected area can be performed.

There are two trends when it comes to treating this type of injury: conservative or surgical, which will depend on many factors, such as age, form of appearance, patient activity and doctor's preferences.

Conservative treatment requires temporary immobilization with rest, analgesic and anti-inflammatory treatment, and then rehabilitative therapy. Surgery resolves the injury immediately but is more painful and risky, and it can leave large scars when the damage cannot be resolved arthroscopically or minimally invasive.

The biceps brachii in culture

Historically, this muscle has represented the highest achievement of body beauty, especially masculine, as a symbol of prestige among warriors and soldiers. It has been exalted in sculpture and other works of art, as well as in photography and film in our times.

It is also a fundamental element in bodybuilding, being one of the most worked muscles and evaluated by athletes and judges in competitions, there are specific exercise regimens for that area of ​​the body that occasionally border on the dangerous and insane.

This bodybuilding practice is one of the main causes of bicipital injuries, and not only because of the physical effort that it entails, but because its damage has been related to the consumption of anabolic steroids, a product widely used by those who practice this sport, even knowingly of the negative consequences they bring with them.

References

1. Cucca, YY et al. (2012). The biceps brachii muscle and its distal insertion: observations of surgical and evolutionary relevance. Surgical and Radiologic Anatomy, 32 (4), 371-375.
2. MEDS Clinic (nd). Biceps pathology. Sports medicine, recovered from: meds.cl.
3. Healthline Medical tean (2015). Biceps Brachii, Retrieved from: healthline.com
4. Prives, M; Lisenkon, N. and Bushkovich, V. (1975). Active part of the musculoskeletal system: arm muscles. Human Anatomy, Second Edition, 343-347.
5. Wikipedia (nd). Biceps brachii muscle, recovered from: en.wikipedia.org.
6. Kanayama, Gen et al. (2015). Ruptured Tendons in Anabolic-Androgenic Steroid Users: A Cross-Sectional Cohort Study. The American Journal of Sports Medicine, 43 (11), 2638-2644.