Ulna

Description

• General
  • Medial bone of the forearm
  • Proximal end articulates with the humerus at the elbow joint and with head of radius at the proximal radioulnar joint
  • Distal end articulates with radius at distal radioulnar joint
  • Ulna is separated from wrist joint by an articular disc
  • The proximal and large end of ulna is the olecranon process forming the prominence of the elbow
• Anatomic Description
  • Trochlear notch is on the anterior surface of ulna and it articulates with trochlea of humerus
  • Coronoid process is located below the trochlear notch
  • Radial notch is located on the lateral surface of the coronoid process and it serves for articulation with the radius
  • Supinator crest is located below the radial notch and it gives origin to the supinator muscle
  • The shaft of ulna goes from above down
  • The shaft has a sharp interosseous border laterally for interosseous membrane attachment
  • The ulna posterior border is rounded and subcutaneous
  • The head of the ulna is located at its distal end
  • The styloid process is a projection from the medial aspect of ulnar head
• Annular Ligament
  • Extends from the surface of the ulna both anterior and posterior to the radial notch and wraps the head of the radius
  • Holding it in the radial notch of the ulna
  • Helps to form the pivot type joint known as the proximal radio-ulnar joint.
• Ulnar Collateral Ligament
  • Located in the medial side of the elbow
  • Attached to the humerus and to the ulna
  • Consists of three bands anterior, posterior and transverse it plays an important role in elbow stability.

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Actions

• Articular
  • Articulates with Humerus to allow flexion and extension at the elbow joint.
  • Articulates with the radius to allow pronation and supination of the forearm, motion at the wrist joint
• Muscle Attachments
  • Anconeus
  • Flexor Carpi Ulnaris
  • Brachialis
  • Pronator Teres
  • Flexor Digitorum Superficialis
  • Flexor Digitorum Profundus

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Vascular supply

• Primarily Ulnar Artery
• Also, Common Interosseous Artery

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Innervation

• Ulnar Nerve

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Clinical Significance

• Distal Ulna Fracture
• Isolated Ulna Fracture
• Radius Ulna Fracture
• Monteggia Fracture
• Ulnar Impingement Syndrome

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See Also

• Hand And Wrist Anatomy
• Forearm Anatomy
• Wrist Pain (Main)
• Forearm Pain (Main)