anatomy of humerus bone

3 min read 10-03-2025

The humerus, the long bone of the upper arm, plays a crucial role in arm movement and overall upper body function. Understanding its intricate anatomy is key to comprehending various injuries and conditions affecting the shoulder and elbow. This comprehensive guide delves into the detailed structure of the humerus, exploring its key features, articulations, and clinical significance.

Key Features of the Humerus

The humerus, the longest and largest bone in the upper limb, is characterized by a distinct shaft (body) and two extremities: the proximal (shoulder) and distal (elbow) ends. Let's break down each part:

Proximal Humerus (Shoulder End)

Head: A smooth, hemispherical articular surface that fits into the glenoid cavity of the scapula (shoulder blade), forming the glenohumeral joint. This joint allows for a wide range of motion.
Anatomical Neck: A constricted area located just below the head, separating it from the tubercles. It's a common site for fractures.
Greater Tubercle: A large, lateral projection providing attachment sites for several rotator cuff muscles (supraspinatus, infraspinatus, and teres minor).
Lesser Tubercle: A smaller, medial projection providing attachment for the subscapularis muscle (another rotator cuff muscle).
Intertubercular Sulcus (Bicipital Groove): A deep groove between the greater and lesser tubercles, housing the long head of the biceps brachii tendon.
Surgical Neck: A slightly constricted region below the tubercles, a common fracture site due to its relatively narrow diameter.

Humeral Shaft (Body)

The humeral shaft is a long, cylindrical structure. Its features include:

Deltoid Tuberosity: A roughened area on the lateral side, serving as the attachment point for the deltoid muscle, the primary abductor of the arm.
Radial Groove: A shallow groove on the posterior aspect, running obliquely downward and laterally. It houses the radial nerve and profunda brachii artery.

Distal Humerus (Elbow End)

The distal end of the humerus articulates with the radius and ulna to form the elbow joint. Key features include:

Capitulum: A rounded, lateral articular surface that articulates with the head of the radius.
Trochlea: A pulley-shaped, medial articular surface that articulates with the trochlear notch of the ulna.
Medial and Lateral Epicondyles: Prominent bony projections on either side of the distal humerus. These serve as attachment points for forearm muscles.
Coronoid Fossa: A depression on the anterior surface that receives the coronoid process of the ulna during flexion of the elbow.
Radial Fossa: A depression on the anterior surface that receives the head of the radius during flexion.
Olecranon Fossa: A deep depression on the posterior surface that receives the olecranon process of the ulna during extension of the elbow.

Articulations of the Humerus

The humerus participates in two major joints:

Glenohumeral Joint (Shoulder Joint): The head of the humerus articulates with the glenoid cavity of the scapula. This is a ball-and-socket joint allowing for extensive movement.
Elbow Joint: The distal humerus articulates with the radius and ulna, forming a hinge joint primarily allowing for flexion and extension, with some rotation.

Clinical Significance

The humerus is susceptible to a variety of injuries and conditions, including:

Fractures: Fractures of the humeral head, surgical neck, and shaft are common, often resulting from falls or high-impact trauma.
Dislocations: The shoulder joint (glenohumeral joint) is prone to dislocation, often caused by forceful impacts.
Rotator Cuff Tears: Injuries to the rotator cuff muscles, which attach to the greater and lesser tubercles, are frequent.
Epicondylitis (Tennis Elbow/Golfer's Elbow): Inflammation of the tendons attached to the medial (golfer's elbow) or lateral (tennis elbow) epicondyles.

Understanding the detailed anatomy of the humerus is vital for diagnosing and treating injuries and conditions affecting the shoulder and elbow. This knowledge forms the basis for effective medical intervention and rehabilitation. Consult with healthcare professionals for any concerns related to your humerus or upper limb health.