Humerus
General
• Long bone of upper limb, bone of the arm.
• Extends from shoulder → elbow.
•Articulates:
•Proximally with scapula (glenoid cavity) → shoulder joint.
•Distally with radius & ulna → elbow joint.
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Humerus radius ulna short notes, Schemes and Mind Maps of Medicine
Bones of upper limb Suject anatomy Topic humerus radius ulna
Typology: Schemes and Mind Maps
2024/2025
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Humerus
General
- Long bone of upper limb, bone of the arm.
- Extends from shoulder → elbow.
- Articulates:
- Proximally with scapula (glenoid cavity) → shoulder joint.
- Distally with radius & ulna → elbow joint.
Parts
- Upper End
- Head → hemispherical, articulates with glenoid cavity.
- Anatomical neck → constriction around head.
- Greater tubercle → lateral, attachment for supraspinatus, infraspinatus, teres minor.
- Lesser tubercle → anterior, subscapularis insertion.
- Intertubercular sulcus (bicipital groove) → lodges tendon of long head of biceps; bounded by crests for pec major (lat. lip), teres major (med. lip), latissimus dorsi (floor).
- Surgical neck → common fracture site; axillary nerve & posterior circumflex humeral artery at risk.
- Shaft
- Deltoid tuberosity → insertion of deltoid.
- Radial (spiral) groove → contains radial nerve & profunda brachii artery.
- Shape: cylindrical (proximal), triangular (distal).
- Lower End
- Condyles:
- Capitulum → articulates with radius.
- Trochlea → articulates with ulna.
- Epicondyles: medial (ulnar nerve behind) & lateral.
- Fossae:
- Coronoid fossa (anterior, ulna).
- Radial fossa (anterior, radius).
- Olecranon fossa (posterior, ulna). ⸻ Ossification
- Primary center: shaft (8th week IU).
- Secondary centers: head, greater tubercle, lesser tubercle, capitulum, trochlea, medial & lateral epicondyles.
- Fusion complete by 20–21 years.
- Mnemonic: “The Lady Got Mad Crazy Tiny Little Head” (Trochlea, Lateral epicondyle, Greater tubercle, Medial epicondyle, Capitulum, Trochlea, Lesser tubercle, Head). ⸻
General
- Long bone of forearm, lateral bone (thumb side).
- Lies parallel to ulna.
- Participates in elbow joint (with humerus & ulna) and wrist joint (with carpal bones). ⸻ Parts
- Upper End
- Head → disc-shaped, articulates with:
- Capitulum of humerus (above).
- Radial notch of ulna (medially).
- Neck → narrow, below head.
- Radial tuberosity → insertion of biceps brachii (posterior rough part).
- Shaft
- Borders: anterior, posterior, interosseous (medial).
- Surfaces: anterior, posterior, lateral.
- Interosseous border → attachment of interosseous membrane.
- Lower End
- Expanded, quadrilateral.
- Radial styloid process → projects downward & laterally.
- Ulnar notch → medial side, articulates with head of ulna.
- Carpal articular surface → articulates with scaphoid & lunate.
- Dorsal tubercle (Lister’s tubercle) → pulley for tendon of extensor pollicis longus. ⸻ Ossification
- Primary center: shaft (8th week IU).
- Secondary centers:
- Lower end (appears 1 year, fuses ~20 years).
- Upper end (appears 4–5 years, fuses ~18 years). ⸻ Applied Anatomy
- Fractures:
- Colles’ fracture → fracture of lower end, distal fragment displaced dorsally (“dinner fork deformity”).
- Smith’s fracture → reverse of Colles, distal fragment displaced ventrally.
- Galeazzi fracture-dislocation → fracture of lower shaft + dislocation of distal radioulnar joint.
- Important in supination & pronation (radius rotates around ulna).
Parts
- Upper End
- Olecranon process → large projection behind; insertion of triceps brachii.
- Coronoid process → projects anteriorly; insertion of brachialis.
- Trochlear notch (semilunar notch) → between olecranon & coronoid; articulates with humeral trochlea.
- Radial notch → lateral side of coronoid; articulates with head of radius.
- Ulnar tuberosity → below coronoid; insertion of brachialis.
- Shaft
- Borders: anterior, posterior, interosseous (lateral).
- Surfaces: anterior, posterior, medial.
- Interosseous border → attachment for interosseous membrane.
- Lower End
- Small, forms head of ulna.
- Styloid process → medial projection.
- Articular surface → articulates with ulnar notch of radius (distal radioulnar joint).
- Does not directly articulate with carpal bones (separated by articular disc). ⸻ Ossification
- Primary center: shaft (8th week IU).
- Secondary centers:
- Lower end (appears 5–6 years, fuses ~18 years).
- Upper end (appears ~10 years, fuses ~20 years). ⸻ Applied Anatomy
- Fractures:
- Monteggia fracture-dislocation → fracture of upper ulna + anterior dislocation of radial head.
- Olecranon fracture → due to fall on flexed elbow, displacement by triceps.
- Important in stabilization of forearm during pronation–supination.