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Humerus – Anatomy Notes
What is the Humerus?
The humerus is the principal bone of the arm (upper limb between shoulder and elbow). Name derived from Latin “humerus” = shoulder. Proximal articulation: o With scapula at the glenohumeral (shoulder) joint Distal articulation: o With radius and ulna at the elbow joint Function: Provides mobility at the shoulder and hinge + pivot movements at the elbow.
Primary Bony Landmarks of the Humerus
1. Head of Humerus
Smooth, rounded, dome-shaped. Articulates with the glenoid cavity of scapula. Forms the glenohumeral joint. Only ⅓ of the humeral head articulates with the glenoid → high mobility, low stability.
2. Neck of Humerus
a. Anatomical Neck Immediately below the head. Attachment site for the joint capsule. b. Surgical Neck Below the tubercles. Clinically important. Axillary nerve and posterior circumflex humeral artery pass around it. Surgical neck fracture → Axillary nerve injury o Leads to deltoid weakness and loss of shoulder abduction.
3. Greater Tubercle
Large projection on lateral and posterior aspect. Attachment for 3 rotator cuff muscles : o Supraspinatus o Infraspinatus o Teres minor
4. Lesser Tubercle
Smaller projection on anterior aspect. Attachment for Subscapularis muscle (4th rotator cuff muscle).
5. Intertubercular Groove (Bicipital Groove)
Groove between greater and lesser tubercles. Contains tendon of long head of biceps brachii. Also called intertubercular sulcus.
6. Shaft of Humerus – Important Features
a. Radial (Spiral) Groove Located on posterior mid-shaft.
Origin of forearm extensor muscles. Involved in tennis elbow.
9. Fossae
a. Coronoid Fossa Anterior, shallow. Accommodates coronoid process of ulna during elbow flexion. b. Olecranon Fossa Posterior, deep. Accommodates olecranon process of ulna during elbow extension.
Clinical Importance Common site of fractures. Closely related to major nerves : o Axillary nerve → surgical neck o Radial nerve → mid-shaft o Ulnar nerve → medial epicondyle Essential for understanding: o Shoulder and elbow movements o Nerve injuries o Orthopedic and surgical anatomy
