Arm Bone Anatomy Overview

Overview

This lecture covers the major bones and key anatomical features of the human arm, focusing on the humerus, radius, and ulna, and their identifying landmarks.

Bones of the Arm

• The arm consists of the humerus (upper arm) and the radius and ulna (forearm).
• The humerus articulates with the scapula at the glenoid cavity via its head.
• The radius is lateral (thumb side) and larger at the wrist; the ulna is medial (pinky side) and larger at the elbow.

Key Features of the Humerus

• The head of the humerus fits into the glenoid cavity of the scapula.
• The greater tubercle (lateral and superior) and lesser tubercle (anterior and lower) serve as muscle attachment points.
• The intertubercular groove lies between the tubercles and holds the tendon of the biceps' long head.
• The deltoid tuberosity (mid-shaft, lateral) is where the deltoid muscle attaches.
• The medial epicondyle (distal, medial) is a bony bump at the elbow for muscle attachment.
• The trochlea (distal, hourglass-shaped) articulates with the ulna.
• The capitulum (distal, lateral) articulates with the head of the radius.

Features of the Radius and Ulna

• The head of the radius is proximal and near the elbow; the radial tuberosity is just below it, for biceps attachment.
• The styloid process of the radius forms the lateral wrist bump.
• The ulna's olecranon (proximal, posterior) forms the bony elbow tip.
• The trochlear notch of the ulna articulates with the humerus’ trochlea.
• The coronoid process is the lower lip of the trochlear notch.
• The radial notch on the ulna is where the head of the radius articulates.
• The styloid process of the ulna is a distal pointed projection near the wrist.

Fossae and Articulating Surfaces

• The olecranon fossa (posterior humerus) receives the olecranon when the elbow is extended.
• The coronoid fossa (anterior humerus) receives the coronoid process during elbow flexion.
• The radial fossa (anterior humerus) receives the radius head during elbow flexion.

Key Terms & Definitions

• Humerus — upper arm bone, connecting shoulder to elbow.
• Radius — lateral forearm bone, larger at the wrist.
• Ulna — medial forearm bone, larger at the elbow.
• Tubercle — projection on a bone for muscle attachment (greater and lesser on humerus).
• Intertubercular groove — groove between tubercles for biceps tendon passage.
• Epicondyle — bony projection for muscle attachment (medial on humerus).
• Trochlea — spool-shaped surface on the humerus for ulna articulation.
• Capitulum — rounded surface on the humerus for radius articulation.
• Olecranon — bony prominence of the ulna forming the elbow.
• Fossa — depression in a bone (olecranon, coronoid, or radial fossae).

Action Items / Next Steps

• Review arm bone diagrams, focusing on key landmarks.
• Practice identifying each feature on models or images.
• Prepare for a quiz on arm bone anatomy.