Humerus Bone

Anatomy Lesson

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Introduction

Anatomical Features

Proximal (Lower) End

At its proximal end is the head of the humerus. This is the large, round, smooth region that faces medially. The head articulates with the glenoid cavity of the scapula to form the glenohumeral (shoulder) joint.

An expanded bony area called the greater tubercle is on the lateral side of the proximal humerus. A smaller lesser tubercle is found on the anterior aspect of the humerus. The tubercles are connected to the tubercular head by the anatomical neck. Both the greater and lesser tubercles are attachment sites for muscles that act across the shoulder joint.

Passing between the greater and lesser tubercles is the intertubercular groove (sulcus). This narrow depression is also known as the bicipital groove because it provides passage for the biceps brachii muscle tendon. The proximal end of the humerus narrows to form the surgical neck, which is a common site of arm fractures.

Proximal End of the Right Humerus Bone

Central Portion

The central portion of the humerus is referred to as the shaft or body. A roughened, V-shaped elevation called the deltoid tuberosity is on the mid-lateral side of the shaft. The name is applied to this structure because it is where the deltoid muscle attaches.

Central Portion of the Right Humerus Bone

Distal (Lower) End

The smooth, rounded distal border of the humerus is referred to as the humeral condyle. It is divided into two surfaces that articulate (join) with the ulna and radius bones of the forearm to form the elbow joint. The more medial of these areas is the pulley-shaped trochlea (L. pulley), which articulates with the ulna bone. Immediately lateral to the trochlea is the capitulum (L. head), a knob-like structure located on the anterior surface of the distal humerus. The capitulum articulates with the radius bone of the forearm.

Just above these bony areas are two small depressions. These spaces accommodate the forearm bones when the elbow is fully bent (flexed). Superior to the trochlea is the coronoid fossa, which receives the coronoid process of the ulna, and above the capitulum is the radial fossa, which receives the head of the radius when the elbow is flexed. Similarly, the posterior humerus has the olecranon fossa, a larger depression that receives the olecranon process of the ulna when the forearm is fully extended.

Superior to (proximal) the humeral condyle are two prominent bony projections. On the medial side is the medial epicondyle and on the lateral side is the much smaller lateral epicondyle. A roughened ridge of bone called the lateral supracondylar ridge is located above the lateral epicondyle. All of these areas are attachment points for muscles that act on the forearm, wrist, and hand. The powerful grasping muscles of the anterior forearm arise from the medial epicondyle, which is thus larger and more robust than the lateral epicondyle that gives rise to the weaker posterior forearm muscles.

Distal End of the Right Humerus Bone

Anterior Humerus Review Quiz

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Attributions

OpenStax, Anatomy and Physiology

Access OpenStax for free at – https://openstax.org/books/anatomy-and-physiology/pages/1-introduction

Reference: “Bones of the Upper Limb“