Elbow Joint

The elbow is the synovial hinge joint between the humerus in the upper arm and the radius and ulna in the forearm. The elbow consists of 3 joints, which form a functional unit enclosed within a single articular capsule. The elbow is the link between the powerful motions of the shoulder and the intricate fine-motor function of the hand. To provide that link, the motions of the elbow include extension and flexion as well as pronation and supination of the forearm.

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Parts of the Elbow Joint

The elbow joint consists of 3 separate articulations enclosed in a single capsule:

JointArticular surfacesTypeFunction
Humeroulnar joint
  • Trochlear notch of ulna
  • Trochlea of the humerus
Simple hinge-joint
  • Flexion-extension
  • Circumduction
Humeroradial joint
  • Head of the radius
  • Capitulum of the humerus
Limited ball-and-socket jointLimited pronation-supination in semiflexion
Proximal radioulnar joint
  • Head of the radius
  • Radial notch of the ulna
Pivot jointPronation-supination in any degree of flexion-extension

Ligaments of the Elbow Joint

The elbow capsule is supported by the ligaments of the elbow, especially the radial (lateral) and ulnar (medial) collateral ligaments.

LigamentAttachmentsFunction
Radial collateral ligament
  • Lateral epicondyle of the humerus
  • Annular ligament of the radius
Stabilizes the elbow joint against varus stress
Ulnar collateral ligament
  • Medial epicondyle of the humerus
  • Coronoid process and olecranon of the ulna
Stabilizes the humeroulnar joint against valgus stress
Annular ligament of the radiusAnterior-posterior margins of the radial notchSurrounds and anchors the radial head to the radial notch of the ulna
Interosseous membraneInterosseous margins of the radius and the ulna
  • Divides forearm into anterior/posterior compartments
  • Stabilizes pronation-supination

Functional Anatomy and Movements of the Elbow Joint

The functional anatomy of the elbow is unique secondary to the orientation and multiple articulations. The main function of the elbow is to link the shoulder and the hand and position and stabilize the hand during activities.

Elbow movement and normal range of motion

Range of motion and movements of the elbow joint

Image by Lecturio.

Carrying angle:

  • Normal valgus carrying angle: 515 degrees
  • Prevents arm from contacting hips
  • Women > men, greater in dominant limb (both sexes)
Carrying angle

Carrying angle

Image by BioDigital, edited by Lecturio

Muscles of the Elbow Joint

The muscles of the elbow originate in the upper arm and insert into the forearm, producing flexion-extension of the elbow as well as supination-pronation of the forearm. The muscles also provide dynamic stabilization to the elbow joint.

MuscleOriginInsertionNerve supplyFunction
Brachialis muscleAnterior aspect of the humerus lateral to the deltoid tuberosityUlnar tuberosityMusculocutaneous nerve (C5–C7)Flexes the elbow and assists with supination
Brachioradialis muscleProximal 2 thirds of lateral supracondylar ridgeLateral surface of distal radius and pre-styloid processRadial nerve (C6)Weak flexor of the elbow, strong flexor when forearm mid-pronated
Biceps brachii muscleShort head: coracoid process; long head: supraglenoid tubercleTuberosity of the radiusMusculocutaneous nerve (C5–C6)Supinates the forearm and assists with elbow flexion
Triceps brachiiLong head: infraglenoid tubercle; lateral and medial heads: posterior humerusOlecranonRadial nerve (C6–C8)Extends the elbow
AnconeusInserts on the posterior aspect of lateral epicondyleLateral surface of the olecranonRadial nerve (C7, C8)Assists in extension of the elbow and stabilizes the joint

Neurovascular and Lymphatic Supply of the Elbow

Innervation

  • Anteriorly: The musculocutaneous, median, and radial nerves pass anterior to the elbow and innervate the anterior capsule.
  • Posteriorly: The ulnar nerve passes posteriorly and medially at the elbow and innervates the posterior capsule.
Nerves of the elbow

Nerves of the elbow

Image by BioDigital, edited by Lecturio

Arterial supply

  • Brachial artery
    • Courses down the anterior surface of the arm into the cubital fossa
    • Bifurcates into the radial and ulnar artery in the proximal forearm
  • The cubital anastomosis is an extensive circulatory system surrounding the elbow, formed from branches of the brachial, radial, and ulnar arteries.
Arteries of the elbow

Arteries of the elbow

Image by BioDigital, edited by Lecturio

Venous drainage

  • Basilic and cephalic vein: the primary superficial veins of the upper arm
  • Connected at the elbow anteriorly by the median cubital vein

Lymphatic drainage

Epitrochlear or cubital lymph nodes are found at the elbow and drain proximally to the axillary lymph nodes.

Clinical Relevance

The following are common conditions related to the elbow:

  • Humerus fracture: A distal humerus fracture primarily occurs from falling on the outstretched arm. Humerus fractures are classified into supra-, trans-, or intercondylar fractures. Depending on the location and the extent of the fractures, these injuries may need to be reduced and addressed surgically. 
  • Supracondylar fracture: a common traumatic fracture in children that occurs from a fall on an outstretched arm or hand. Treatment often includes closed reduction and percutaneous pinning, which may be urgent if the neurovascular system is compromised.
  • Olecranon fracture: occurs secondary to falling on the flexed arm. Depending on the complexity of the fracture, the fracture may be treated surgically with a tension band osteosynthesis.
  • Radial head fracture: 1 of the most common fractures in adults; occurs secondary to falling on the extended arm. Can occur with or without dislocation and may include multiple fragments. May require surgical management.
  • Elbow dislocation: 2nd-most common joint dislocation after the shoulder. A fall on an outstretched hand is the usual mode of injury. Complex elbow dislocations have an associated fracture or neurovascular injury.
  • Nursemaid’s elbow (radial head subluxation): also called “babysitter’s elbow.” Common injury of young children that occurs secondary to longitudinal traction on the hand and forearm. Causes a subluxation of the annular ligament from the normal location surrounding the radial head. Treatment is usually closed reduction using a supination technique.
  • Medial/lateral epicondylitis or flexor/extensor tendinosis: a common problem of the elbow, with localized pain at either the lateral (extensor) or medial (flexor) epicondyle. Associated with inflammation or degeneration of the tendons of the area due to repetitive microtrauma/overuse. Medial epicondylitis or flexor tendinosis is also known as “golfer’s elbow,” while lateral epicondylitis or extensor tendinosis is known as “tennis elbow.”
  • Ulnar nerve compression syndrome: also called cubital tunnel syndrome. Usually due to a direct trauma of the ulnar nerve or repetitive/prolonged elbow flexion. Less commonly secondary to hypermobility of the ulnar nerve or osteophytes in the cubital tunnel.

References

  1. Drake, R.L., Vogl, A.W., & Mitchell, A.W.M. (2014). Gray’s Anatomy for Students (3rd ed.). Philadelphia, PA:  Churchill Livingstone.

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