Download File - Wk 1-2

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)
 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
 SITE: weakest part is the junction of the middle and lateral thirds
 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
 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
 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
 STRUCTURES ENDANGERED
o NERVES - axillary
o VESSELS – anterior and posterior circumflex arteries
(iii) fracture of shaft of humerus
 MECHANISM
o transverse fractures often result from direct blow to the arm
 EFFECT:
o pull of deltoid pulls proximal fragment of fractured humerus laterally
 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
 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
 MECHANISM:
 EFFECT:
o pain on supination and pronation
o tender over radial head
(ii) fracture of lower end of radius
 MECHANISM:
o fall on outstretched hand
 SITE:
o Colles’s Fracture (dinner fork deformity): complete transverse fracture within
the distal 2cm of radius, is most common
 STRUCTURES ENDANGERED
o NERVES - radial
o VESSELS – radial artery
(iii) fracture of scaphoid (with particular reference to its blood supply).
 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
 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)
 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
 STRUCTURES ENDANGERED
o NERVES – axillary nerve
(ii) dislocation of elbow joint (uncommon)
 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
 STRUCTURES ENDANGERED
o NERVES – ulnar nerve (numbness of little finger and weakness of flexion and
adduction of the
wrist)