Humerus Bone Anatomy

Author: Scott A. Sheffield MS

Last update: Jul 27th, 2023

The humerus, or the arm bone, is the only bone in the arm and the longest bone of the upper limb. It is a long bone that extends from the shoulder to the elbow. Proximally, it articulates with the scapula to form the shoulder (glenohumeral) joint. This joint connects the upper limb to the trunk. It is also the most mobile joint in the body, enabling a wide range of motion for the upper limb.

Distally, the humerus articulates with the radius and ulna, with which it comprises the elbow joint. The humerus consists of the proximal and distal ends, with a shaft between them. Numerous muscles attach to the humerus, enabling a great array of movement for the arm.

This article will present the anatomy of the humerus, focusing on its parts and bone markings.

Key points about the anatomy of the humerus
Proximal end	Head of humerus Anatomical neck Surgical neck Greater tubercle Lesser tubercle Intertubercular sulcus Crest of greater tubercle Crest of lesser tubercle
Shaft	Borders: Anterior, lateral and medial Surfaces: Anterolateral, anteromedial, posterior
Distal end	Lateral and medial supracondylar ridges Lateral and medial epicondyles Condyle of humerus: trochlea, capitulum, olecranon fossa, radial fossa, coronoid fossa

Proximal end

The proximal part of the humerus features the head, two necks and two tubercules. The head of humerus is spherical and it features a large articular surface for the joint with the glenoid cavity of the scapula. This articular surface is circumscribed by a circular groove, called the anatomical neck of the humerus.

The anatomical neck clearly separates the humeral head from two bony bumps called the greater tubercle (found on the lateral side of the bone) and lesser tubercle of humerus (on the anterior side of the bone), which serve as attachment sites for several muscles. Between these tubercles is a shallow depression called the intertubercular sulcus or bicipital groove. The tubercles continue distally as two separate crests, called the crest of greater tubercle and crest of lesser tubercle, respectively.

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Distally to the tubercules, the proximal end of the humerus gradually becomes thinner, forming an area called the surgical neck of humerus. This constriction of the bone is named that way because it is a common site of humeral fractures.

Body

The shaft of the humerus has three borders and three surfaces. Namely, the borders are the anterior, lateral and medial. They separate the three humeral surfaces called the anteromedial, anterolateral and posterior surface.

All three surfaces are relatively unremarkable and smooth. The anterolateral surface which features a bump called the deltoid tuberosity, which serves as an attachment site for the deltoid muscle. The posterior surface features a shallow sulcus called the radial groove for the passage of the radial nerve and deep brachial artery.

Distal end

The distal part of the humerus features several parts. The lateral and medial borders of the humeral shaft continue into the distal end to form two ridges: lateral and medial supracondylar ridges. Each ridge terminates with a bony prominence, called lateral and medial epicondyle of humerus, respectively. The epicondyles serve as attachment points for several forearm muscles.

The most distal part of the humerus is called the condyle of humerus and it plays a key role in the formation of the elbow joint as it articulates with the radius and ulna.

The condyle consists of two articular and three non articular bony landmarks. The articular bony landmarks directly participate in the elbow joint. They are the trochlea and the capitulum of the humerus. The trochlea is found on the medial side of the distal end of the humerus. It articulates with the trochlear notch of the ulna. The capitulum is a rounded knob on the humerus that articulates with the head of the radius. It is located laterally to the trochlea.

The remaining landmarks of the distal end of the humerus don’t participate directly in the elbow joint, and they are called the olecranon, coronoid and radial fossae.

The coronoid and radial fossae are two depressions found on the anterior side of the humerus. The olecranon fossa is located on the posterior side of the humerus. It is important for the elbow extension, as the tip of the ulnar olecranon process lodges into it. The coronoid fossa serves for lodging in the coronoid process of ulna during forearm flexion, while the radial fossa receives the head of radius.

Humerus anatomy quiz

Take this quiz on humerus bony landmarks to solidify your knowledge:

References

• Open Anatomy. (n.d.). TA2 Viewer. Retrieved April 5, 2023, from https://ta2viewer.openanatomy.org/
• Moore, K. L. (2018). Clinically Oriented Anatomy (8th ed.). Philadelphia, PA: Wolters Kluwer.
• Drake, R. L., Vogl, A. W., & Mitchell, A. W. M. (2015). Gray’s Anatomy for Students (3rd ed.). Edinburgh, Scotland: Churchill Livingstone.
• Standring, S. (2021). Gray’s Anatomy (42tst ed.). Edinburgh: Elsevier Churchill Livingstone.