• Clinical science

Upper arm and elbow

Summary

The upper arm, or brachium, extends between the shoulder joint and elbow. The shoulder joint connects the upper arm to the torso and the shoulder girdle, while the elbow joint connects it to the forearm. The muscles of the upper arm move the elbow joint (flexion and extension) and the forearm (pronation and supination), as well as stabilize and move the shoulder joint (internal rotation and flexion). This learning card covers the bones, muscles, vasculature, lymphatics, and innervation of the upper arm and elbow.

The forearm, wrist, and hand are discussed elsewhere, as are the shoulder, axilla, and brachial plexus.

Bones

The humerus is a bone of the arm that articulates proximally with the scapula to form the shoulder joint and distally with the radius and ulna to form the elbow joint.

Head of the humerus

Spherical proximal portion of the humerus that articulates with the glenoid cavity of the scapula (i.e., the ball of the ball-and-socket glenohumeral joint)

Neck of the humerus

Shaft of the humerus

Humerus fractures can also involve injuries to neighboring structures. From proximal to distal, the nerves that can be injured along with a humerus fracture are the nerves of the A-R-M (axillary, radial, median). Fractures at the surgical neck of the humerus can injure the axillary nerve (along with the posterior circumflex humeral artery). Fractures of the humeral shaft can injure the radial nerve (along with the deep brachial artery). Fractures of the distal humerus (supracondylar fractures) can injure the median nerve (along with the brachial artery).

Tendinosis at the medial epicondyle (medial epicondylitis) is called golfer's elbow, while tendinosis at the lateral elbow (lateral epicondylitis) is called tennis elbow.References:[1]

Muscles

The muscles of the arm can be categorized into two groups: flexors and extensors. They lie deep to the brachial fascia and are divided into anterior (flexor) and posterior (extensor) compartments by the medial intermuscular septum and the lateral intermuscular septum.

For specific tests to assess the function of these muscles, see “Motor function” in neurological examination.

Anterior compartment of the arm (flexors)

The anterior compartment contains three muscles that are elbow flexors, all of which are innervated by the musculocutaneous nerve.

Muscle Origin Insertion Innervation Function
Biceps brachii
  • Musculocutaneous nerve (C5–C7)
  • Elbow: flexion
  • Forearm: supination (strongest supinator)
  • Shoulder: internal rotation and flexion
    • Long head: shoulder abduction
    • Short head: shoulder adduction

Brachialis

  • Ulnar tuberosity

Coracobrachialis

  • Shoulder: arm flexion, adduction (weak)

The elbow flexors are innervated by the musculocutaneous nerve.

A common tendon rupture of the arm is biceps tendon tear, which classically causes the “Popeye sign” on examination.

Posterior compartment of the arm (extensors)

The posterior compartment contains two muscles that are elbow extensors, both of which are innervated by the radial nerve.

Muscle Origin Insertion Innervation Function
Triceps brachii
  • Radial nerve (C5-T1)
  • Shoulder: adduction and extension
  • Elbow: extension
Anconeus muscle
  • Dorsal ulnar surface distal of the olecranon

The elbow extensors are innervated by the radial nerve.

Vasculature and lymphatics

Arterial supply

Brachial artery: main artery of the arm, forearm, and hand

The brachial artery can be compressed proximally against the medial humerus to stop bleeding in the distal arm.

Venous drainage

Lymphatic drainage

Innervation

Motor and sensory innervation of the arm and elbow

Function Nerve Innervated structures

Motor

  • Musculocutaneous nerve
  • Radial nerve

Sensory

  • Skin over the inferomedial aspect of the arm
  • Skin over the inferior aspect of the deltoid
  • Skin over the inferolateral aspect of the arm
  • Skin over the distal third of the posterior arm
  • Intercostobrachial nerve (branch of the second intercostal nerve)
  • Skin over the proximal half of the medial arm
  • For more on the clinical presentation of upper limb nerve lesions, see the section “Nerve injuries in the upper body” in peripheral nerve injuries.
  • For tests to assess the function of these nerves, see “Motor function” and “Sensation” in neurological examination.

Dermatomal distribution of the arm

  • Skin over shoulder: C4
  • Lateral arm: C5
  • Posterior arm (elbow): C6
  • Inferomedial arm: T1
  • Superomedial arm: T2

Elbow joint

Radial head subluxation (nursemaid elbow) is a partial subluxation of the radial head at the radiohumeral joint and is caused by excessive axial traction. It is the most common elbow injury in children < 5 years old.

References:[2]

Cubital fossa (antecubital fossa)

The median cubital vein of the antecubital fossa is one of the most common sites for peripheral venipuncture and intravenous access.

The epitrochlear lymph nodes are classically enlarged in syphilis and sarcoidosis.

For the contents of the cubital fossa (from lateral to medial), remember “Really Need Beer To Be At My Nicest” = Radial Nerve, Biceps Tendon, Brachial Artery, Median Nerve.References:[3][4]

  • 1. Frontera WR, Silver JK, Rizzo TD. Essentials of Physical Medicine and Rehabilitation E-Book. Elsevier Health Sciences; 2014.
  • 2. Dhillon MS, Gopinathan NR, Kumar V. Misconceptions about the three point bony relationship of the elbow. Indian J Orthop. 2014; 48(5): pp. 453–7. doi: 10.4103/0019-5413.139835.
  • 3. Standring S. Gray's Anatomy: The Anatomical Basis of Clinical Practice. Elsevier Health Sciences; 2016.
  • 4. Catalano O, Nunziata A, Saturnino PP, Siani A. Epitrochlear lymph nodes: Anatomy, clinical aspects, and sonography features. Pictorial essay. J Ultrasound. 2010; 13(4): pp. 168–74. doi: 10.1016/j.jus.2010.10.010.
last updated 09/27/2019
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