Overview
This lecture covers the bones and major anatomical landmarks of the upper limb, focusing on the humerus, ulna, radius, and the bones of the wrist and hand.
Humerus Structure & Landmarks
- The head of the humerus articulates with the glenoid cavity of the scapula using articular cartilage.
- The anatomical neck is just behind the head and is the rotation point during movement.
- The surgical neck, inferior to the anatomical neck, is a common fracture site.
- Greater and lesser tubercles are muscle attachment sites; the intertubercular groove (sulcus) lies between them.
- The deltoid tuberosity on the shaft serves as the deltoid muscle attachment.
- The distal humerus features the trochlea (articulates with ulna) and capitulum (articulates with radius).
- Medial and lateral epicondyles protrude from the distal end; the medial side is determined by the direction of the humeral head.
- Olecranon fossa (posterior) and coronoid fossa (anterior) accommodate ulna processes during elbow movement.
- The radial fossa on the humerus allows space for the head of the radius during flexion.
Ulna & Radius Structure
- Ulna's trochlear notch grips the humerus' trochlea for elbow joint movement.
- The olecranon (elbow tip) and coronoid process of the ulna fit into corresponding fossae on the humerus.
- The radial notch on the ulna receives the head of the radius.
- Both ulna and radius have tuberosities for muscle attachment.
- The distal end of the ulna is called the head and includes a styloid process.
- The radius has its head at the proximal end, with a distal styloid process.
- The interosseous membrane links the radius and ulna for stability.
- Styloid processes of the radius and ulna help secure the wrist bones.
Wrist and Hand Bones
- There are 8 carpal (wrist) bones: scaphoid, lunate, triquetrum, pisiform (pinky side); hamate, capitate, trapezoid, trapezium (thumb side).
- Mnemonic for carpal bones: "So Long To Pinky, Here Comes The Thumb" (start on thumb/radius side).
- Metacarpal bones (1–5) form the palm, numbered from thumb (1) to pinky (5).
- Phalanges are finger bones: each finger has proximal, middle, and distal phalanges, except the thumb, which has only proximal and distal.
- Each hand contains 14 phalanges.
Key Terms & Definitions
- Humerus — long bone of the upper arm.
- Glenoid cavity — shallow socket in the scapula for the humerus head.
- Tubercle — small rounded projection for muscle attachment.
- Fossa — shallow depression in a bone.
- Trochlea — spool-shaped structure on humerus articulating with ulna.
- Capitulum — rounded knob on humerus articulating with the radius.
- Olecranon — bony tip of the ulna (elbow).
- Styloid process — pointed bone projection at distal ends of radius/ulna.
- Interosseous membrane — ligamentous sheet connecting radius and ulna.
- Carpal bones — eight bones forming the wrist.
- Metacarpals — bones forming the palm.
- Phalanges — bones of the fingers.
Action Items / Next Steps
- Memorize the names and order of carpal bones using a mnemonic.
- Review diagrams or videos illustrating the anatomical landmarks and bone articulations of the upper limb.