Arm - Anatomy, Physiology, Pain

Arm – Anatomy, Physiology, Pain

The arm (from the Latin brachium), sometimes called hindarm, corresponds to the part of the upper limb located between the shoulder and the elbow.

Anatomy of the arm

Structure. The arm consists of a single bone: the humerus. The latter and the intermuscular septums separate the muscles into two distinct parts:

  • the anterior compartment, which includes three flexor muscles, the biceps brachial, the coraco brachial, and the brachial
  • the posterior compartment, consisting of a single extensor muscle, the triceps brachial

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

Arm movements

Supination movement. The biceps brachial muscle participates in the supination movement of the forearm. (2) This movement makes it possible to orient the palm of the hand upwards.

Elbow flexion/extension movement. The biceps brachial, as well as the brachial muscle, participate in the flexion of the elbow while the triceps brachial muscle is responsible for the extension of the elbow.

Arm movement. The coracobrachialis muscle has a flexor and adductor role in the arm.

Pathologies and diseases of the arm

Arm pain. 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 in the diaphysis (central part of the humerus), the lower end (elbow), or the upper end (shoulder). The latter may be accompanied by a dislocation of the shoulder.
  • Tendinopathy. They designate all pathologies that can occur in the tendons. The causes of these pathologies can be varied. The origin can be both intrinsic with genetic predispositions, and extrinsic, with for example bad positions during sports practice. At the shoulder, the rotator cuff which corresponds to all the tendons covering the head of the humerus, as well as the tendons of the long biceps and biceps brachial can be affected by tendonitis, that is to say, inflammation of the tendons. In some cases, these pathologies can worsen and cause the rupture of the tendons.
  • Myopathy. It includes all neuromuscular diseases affecting muscle tissue, including those of the arm.

Prevention and treatment of the arm

Drug therapy. 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 screwed plate, an external fixator, or in some cases a prosthesis.

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

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

Arm exams

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

Medical imaging examination. Examinations by radiography, scanner, MRI, scintigraphy, or bone densitometry can be used to confirm or deepen the diagnosis.

History and symbolism of the arm

When one of the tendons of the biceps brachial 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.

Image Credit: Photo by Andrea Piacquadio from pexels.com

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