Applied Anatomy of Bones & Joints of Upper Limb Week 28 LOs
Understand the concepts & associated principles, functional &clinical applications of:
1. the site, mechanism, effect, and in particular the anatomical structures(s) endangered by:
(i) fracture of clavicle
 common in adults and children (although more common in the more slender clavicle of a child)
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MECHANISM: o fractured by indirect force resulting from violent impacts to the outstretched hand during a fall that are transmitted up the forearm and arm to the shoulder itself o or by direct impact to the shoulder itself
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SITE: weakest part is the junction of the middle and lateral thirds
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EFFECT: o after fracture the SCM muscle elevates the medial fragment o the trapezius is unable to hold up the lateral fragment (due to weight of upper limb) and the shoulder drops o the coroclavicular ligament usually prevents dislocation of the AC joint
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Structures endangered: o NERVES – phrenic, vagus and brachial plexus o VESSELS – subclavian artery and vein, vertebral arteries o VISCERA – apex of lung
(ii) fracture of surgical neck of humerus
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MECHANISM: o most injuries of proximal end occur here o especially common in the elderly o humeral fractures are often impacted (one fragment is driven into the spongy bone of the other) o usually result from minor fall ion hand with force transmitted up the forearm o due to impaction the fracture site is stable and arm can be moved passively with little pain
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STRUCTURES ENDANGERED o NERVES - axillary o VESSELS – anterior and posterior circumflex arteries
(iii) fracture of shaft of humerus
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MECHANISM o transverse fractures often result from direct blow to the arm
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EFFECT: o pull of deltoid pulls proximal fragment of fractured humerus laterally
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STRUCTURES ENDANGERED o NERVES – distal end of humerus – radial nerve (wrist and finger extension) o VESSELS – basilic and cephalic veins, brachial artery

(iv) supracondylar fracture of humerus
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MECHANISM: o fracture in distal part of humerus near the supracondylar ridges o distal bone fragment may be displaced anteriorly or posteriorly
 o
STRUCTURES ENDANGERED o NERVES – median nerve o VESSELS – brachial vessels
2. the site, mechanism and effect of:
(i) fracture of head of radius
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MECHANISM:
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EFFECT: o pain on supination and pronation o tender over radial head
(ii) fracture of lower end of radius
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MECHANISM: o fall on outstretched hand
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SITE: o Colles’s Fracture (dinner fork deformity): complete transverse fracture within the distal 2cm of radius, is most common
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STRUCTURES ENDANGERED o NERVES - radial o VESSELS – radial artery

(iii) fracture of scaphoid (with particular reference to its blood supply).
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MECHANISM: o most frequently fractured carpal bone and fracture of scaphoid is most common injury of the wrist, especially as a result of fall onto the palm when the hand is abducted
 poor blood supply to the proximal part of the scaphoid means that union of the fractured parts may take several months
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avascular necrosis of the proximal fragment of the scaphoid may occur and produce degenerative joint disease of the wrist
3. the mechanism, diagnosis and structures endangered by:
(i) dislocation of shoulder joint (common)
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MECHANISM: o common by direct or indirect injury due large freedom of movement and instability o coracoacromial arch and rotator cuff prevents superior dislocation and most dislocations occur inferiorly o displacement inferoanteriorly most common o loss of deltoid contour o patient is unable to use the arm and often supports it with the other hand
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STRUCTURES ENDANGERED o NERVES – axillary nerve
(ii) dislocation of elbow joint (uncommon)
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MECHANISM: o posterior dislocation of the elbow joint may occur when children fall on their hands with their elbow flexed o hyperextension or a blow that drives the ulna posterior or posterolateral o distal end of humerus is driven through the weak anterior part of the fibrous capsule as the radius and ulna dislocate posteriorly o ulnar collateral ligament is often torn o associated fracture of head of radius, coronoid process or olecranon process of ulna may occur
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STRUCTURES ENDANGERED o NERVES – ulnar nerve (numbness of little finger and weakness of flexion and adduction of the wrist)