The arm (from the Latin brachium), sometimes called the forearm, is the part of the upper limb between the shoulder and elbow.

Structure. The arm is made up of a single bone: the humerus. The latter as well as the intermuscular partitions separate the muscles into two distinct parts:

• the anterior compartment, which groups together three flexor muscles, the biceps brachii, the coraco brachialis and the brachialis
• the posterior compartment, made up of a single extensor muscle, the triceps brachii

Innervation and vascularization. The innervation of the arm is supported by the musculocutaneous nerve, the radial nerve, and the medial cutaneous nerve of the arm (1). The arm is deeply vascularized by the brachial artery as well as the brachial veins.

Supination movement. The biceps brachii muscle participates in the supination movement of the forearm. (2) This movement allows the palm of the hand to be oriented upwards.

Elbow flexion / extension movement. The biceps brachii as well as the brachii muscle are involved in flexing the elbow while the triceps brachii muscle is responsible for extending the elbow.

Arm movement. The coraco-brachialis muscle has a flexor and adductor role in the arm. (3)

Pain in the arm. Pain is frequently felt in the arm. The causes of these pains are varied and can be associated with muscles, bones, tendons or joints.

• Fractures. The humerus can be the site of fractures, whether at the level of the shaft (central part of the humerus), the lower extremity (elbow), or the upper extremity (shoulder). The latter may be accompanied by a dislocation of the shoulder (3).
• Tendinopathies. They designate all the pathologies that can occur in the tendons. The causes of these pathologies can be varied. The origin can be intrinsic as well with genetic predispositions, as extrinsic, with for example bad positions during the practice of sport. At the level of the shoulder, the rotator cuff which corresponds to the set of tendons covering the head of the humerus, as well as the tendons of the long biceps and the biceps brachii can be affected by tendonitis, that is to say – say inflammation of the tendons. In some cases, these conditions can worsen and cause tendon rupture. (4)
• Myopathy. It covers all neuromuscular diseases affecting muscle tissue, including those of the arm. (5)

Medical treatment. Depending on the disease, different treatments may be prescribed to regulate or strengthen bone tissue or reduce pain and inflammation.

Surgical treatment. Depending on the type of fracture, surgery can be performed with the placement of pins, a screw-retained plate, an external fixator or in some cases a prosthesis.

Orthopedic treatment. Depending on the type of fracture, the installation of a plaster or a resin can be carried out.

Physical treatment. Physical therapies such as physiotherapy or physiotherapy can be prescribed.

Physical examination. Diagnosis begins with an assessment of forearm pain to identify its causes.

Medical imaging exam. X-ray, CT, MRI, scintigraphy or bone densitometry examinations can be used to confirm or deepen the diagnosis.

When one of the tendons of the biceps brachii ruptures, the muscle can retract. This symptom is called “Popeye’s sign” in comparison to the ball formed by the biceps of the fictional character Popeye (4).