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Humerus

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General

  • The humerus is a long bone that has both a shaft (diaphysis) and two regions of articulation (epiphysis)
  • The humerus is the longest bone in the upper extremity.
  • The proximal or upper portion of the humerus consists of the bone's large rounded head joined to the body by a constricted portion called the neck and two eminences the greater and lesser tubercles.

Anatomic Description

Illustration of the humerus anatomy with labels[1]
Lateral xray of a normal humerus[2]
PA xray of a normal humerus[2]

Proximal Humerus

  • Head
    • Hemispheric head covered in articular cartilage
    • Articulates with the glenoid fossa
    • Forms that lateral half of the glenohumeral joint
  • Anatomical neck
    • Just below the head
    • Represents the distal attachment of the joint capsule
  • Greater tubercle
  • Lesser tubercle
    • Located anterior to the to the anatomical neck
    • Attachments: subscapularis
  • Intertubercular sulcus
    • Also known as the bicipital groove
    • Indentation between the greater and lesser tubercle
    • Long head of the biceps brachii can be found in the groove
  • Tendon of teres minor attaches to the medial lip
  • Surgical neck

Humeral Shaft

  • Proximal half is cylindrical, distal half is triangular
  • Anterior Border
    • Begins at the greater tubercle, runs downward almost to the end of the bone
    • Proximal end is continuous with the lateral lip of the intertubercular sulcus
  • Lateral border
    • Begins just distal to the greater tubercle
    • Thickens distally to form the lateral supracondylar ridge
    • Middle portion of the lateral border is adjacent to the rough V shaped area referred to as the deltoid tubercle/tuberosity.
  • Medial border
    • Forms the medial supracondylar ridge distally
    • Radial groove: shallow groove that interrupts the lateral border in its medial third.
    • Contains radial nerve, deep brachial artery
  • Anterolateral surface
    • Limited between the anterior, lateral borders
    • Deltoid attaches to the proximal smooth surface, deltoid tuberosity on middle surface
    • Lateral brachialis originates from the distal part of this surface, proximal two third of the lateral supracondylar ridge
  • Anteromedial surface
    • Located between the anterior and medial borders
    • Begins proximally at the floor of the intertubercular sulcus.
    • Coracobrachialis attaches around its mid-portion
    • Brachialis covers distal half
  • Posterior surface
    • Bounded by the medial, lateral borders
    • Covered mostly by the medial head of the triceps brachii
    • Proximal third also gives attachment to the lateral head of the triceps brachii.

Distal Humerus

  • General
    • Consists of articular and non-articular components
    • Articular part is widened condyle articulating with both the proximal radius, ulna
  • Trochlea
    • The trochlea has a surface shaped like a pulley
    • Covers the anterior, posterior and inferior surfaces of the medial condyle of the humerus
    • Articulates with ulna at trochlear notch
    • Elbow extension: posterior, inferior aspects articulate with ulna
    • Elbow flexion: anterior, inferior parts articulate with ulna
  • Capitellum
    • Convex and rounded projection that articulates with the head of the radius
    • Covers the anterior, inferior surfaces of the lateral condyle of the humerus
    • Extension: inferior surfrace in contact with humerus
    • Flexion: radial head slides towards anterior aspect humerus
  • Medial Epicondyle
  • Lateral Epicondyle
  • Olecranon Fossa
    • The olecranon fossa is a deep hollowed area on the posterior surface, superior to the trochlea.
    • In elbow extension, the tip of the ulnar olecranon process lodges into this fossa.
  • Coronoid Fossa
    • Located superior to trochlea on the anterior surface
    • Coronoid process of ulna lodges here in elbow flexion
  • Radal Fossa
    • Located on anterior humerus
    • Head of the radius sits here with the elbow in full flexion

Osteology

Humeral Head

  • Four growth center: head, shaft, greater tubercle, lesser tubercle[3]
  • Typically fuses between ages 14-20
  • Contributes about 80% of longitudinal growth of humeral shaft

Vascular Supply

  • Proximally
    • Anterior circumflex humeral artery
    • Posterior circumflex humeral artery

Innervation

  • Needs to be updated

Clinical Significance

Proximal

Shaft

Distal


See Also


References

  1. Image courtesy of https://www.theskeletalsystem.net/
  2. 2.0 2.1 Case courtesy of Piotr Gołofit, Radiopaedia.org, rID: 53034
  3. www.wheelessonline.com/ortho/anatomy_of_proximal_humeral_physis. Accessed March 7, 2010.
Created by:
Atfreeceu on 22 July 2021 05:54:39
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Last edited:
6 June 2023 16:46:42
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