Anatomy Of The Upper Limb - Bones And Joints

Front 1

Bones of the shoulder girdle - function

Back 1

Clavicle and scapula - provide a mobile base to attach the limbs to the trunk

Front 2

Functions of the clavicle (3)

Back 2

- Strut to distance the scapula and upper limb from the chest wall
- Articulates with the sternum and the acromion process of the scapula
- Transmits forces to the axial skeleton (fracture - fall on an outstretched arm)

Front 3

Scapula - articulation and function

Back 3

- Articulates with the humerus at the glenoid fossa
- Provides large, flat surfaces and rough processes for muscle attachment

Front 4

Sternoclavicular joint features

Back 4

Between - medial end of clavicle and upper lateral edge of manubrium
Atypical synovial joint - surfaces covered by fibrocartilage
Enclosed by synovial capsule, reinforced by anterior and posterior sternoclavicular and costoclavicular ligaments
Joint divided into two cavities by a fibrocartilaginous disc

Front 5

Acromioclavicular joint features

Back 5

Between lateral end of clavicle and medial edge of acromion process
Atypical synovial joint
Weakly encapsulated - stabilised by coracoclavicular and acromioclavicular ligaments

Front 6

Glenohumeral joint features

Back 6

Between glenoid fossa and humeral head
Most mobile joint in body - ball-and-socket synovial joint
Shallow joint - low surface area of articulation (unstable - prone to dislocation)
Thin synovial capsule - loose inferiorly to permit wide range of movement
Capsule strengthened by rotator cuff tendons
Glenoid labrum (fibrocartilaginous rim at fossa margin) deepens the joint and helps to stabilise

Front 7

Bones of the upper arm

Back 7

- Humerus
- Radius
- Ulna

Front 8

Humerus - features and functions

Back 8

Mobile lever - directs forearm movement in any direction
Articulates the scapula at the head, the radius at the capitulum and the ulna at the trochlea.
Forearm angled laterally with respect to the humerus (carrying angle) by the trochlea (projects further at its medial that its lateral border)
Often fractures at the 'surgical neck'

Front 9

Radius - features and functions

Back 9

Thick, disc-like head articulates with humerus
Distal end articulates with scaphoid and lunate carpal bones
Colles fracture - fractured radius due to fall on an outstretched hand

Front 10

Ulna - features and functions

Back 10

Articulates with humerus at the trochlea notch via the olecranon which prevents overextension of (locks) the elbow joint
Articulates with the radial head at the radial notch

Front 11

Elbow joint features

Back 11

Synovial hinge joint
Articulations - trochlea of humerus and trochlea notch of ulna, humerus capitulum and radial head, radial head and radial notch (proximal radio-ulna joint)
Capsule covers all 3 articulations - reinforced by radial and ulna collateral ligaments (lateral and medial ligaments)
Proximal radio-ulna joint held together by the annular ligament - permits rotation of the radial head on ulna
CLINICAL: fall on an outstretched hand = posterior dislocation

Front 12

Interosseous membrane

Back 12

Joins shafts of radius and ulna
Fibrous sheet - syndesmosis

Front 13

Distal radio-ulna joint

Back 13

Between ulnar notch of radius and the ulnar head
Radius and ulna united by intra-articular disc - a triangle of fibrocartilage

Front 14

Carpal bones - features and functions

Back 14

Transversely arched - creates a hollow
Provides flexible yet firm basis on which muscles can exert their action
Scaphoid prone to fracture through fall on outstretched hand

Front 15

Radio-carpal joint

Back 15

Synovial ellipsoid joint between distal end of radius + intra-articular disc and the proximal row of carpals
Strengthened by radial and ulnar collateral and dorsal and palmar ligaments
Flexor retinaculum (transverse carpal ligament) - runs from (medially) pisiform and hook of hamate to (laterally) scaphoid and trapezium
Forms the carpal tunnel - the flexor tendons of the digits and the median nerve run through this
Merges with palmar aponeurosis (protective, tendon-like sheet) originating from the tendon of palmaris longus
Extensor tendons run under the thinner, extensor retinaculum - runs across the back of the wrist from the pisiform and hook of hamate to the radius forming channels by spanning grooves on the dorsal aspect of the distal radius.

Front 16

Metacarpals - features and functions

Back 16

1st is support for the base of the thumb
Remaining 4 form the framework of the palm
Relatively immobile (only the thumb moves freely)

Front 17

Phalanges - features and functions

Back 17

Bones of the fingers (3) and thumb (2)
Function as a unit rather than individual bones