Humerus

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
- Three smooth, flat impressions located posterosuperiorly
- Attachments from superior to inferior: supraspinatus, infraspinatus, teres minor
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 pectoralis major attaches to the lateral lip
Tendon of teres minor attaches to the medial lip
- Latissimus dorsi attaches to the posterior aspect
Surgical neck
- Narrowing just below the tubercles
- Close proximty to axillary nerve, posterior circumflex humeral artery
- Represents transition to shaft

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
- Blunt landmark superomedial to the medial condyle
- Ulnar Nerve passes posterior
- The common flexor tendon attaches here
- Composed of flexor carpi ulnaris, Palmeris Longus, flexor carpi radialis, Pronator Teres
Lateral Epicondyle
- Landmark superolateral to the lateral condyle
- Attachment site of the common extensor tendon
- Composed of brachioradialis, extensor carpi radialis longus, extensor carpi radialis brevis, Extensor digitorium, extensor digiti minimi, extensor carpi ulnaris, Anconeus
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

Humeral Shaft Fracture

Distal

References

↑ Image courtesy of https://www.theskeletalsystem.net/
↑ ^2.0 ^2.1 Case courtesy of Piotr Gołofit, Radiopaedia.org, rID: 53034
↑ www.wheelessonline.com/ortho/anatomy_of_proximal_humeral_physis. Accessed March 7, 2010.

Created by:

Atfreeceu on 22 July 2021 05:54:39

Authors:

John Kiel, Atfreeceu

Last edited:

6 June 2023 16:46:42

Category:

Anatomy

[1] Image courtesy of https://www.theskeletalsystem.net/

[golofit-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.

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