Shoulder/Elbow Anatomy Flashcards
describe synovial membrane?
highly vascular/neuro
what happens if you tear synovial membrane?
haemarthrosis
describe articular cartilage
on surface of bones in a joint
avascular
aneural
Fibrous capsule reinforced by 3 things
stabilizer muscles
intrinsic ligaments
extrinsic/accessory ligaments
what is the labrum for? 2 things
deepens glenoid
provides attachment site (e.g.. long head biceps)
what is intra-articular but extrasynovial in joints? purpose?
fat pad, used to distribute synovial fluid evenly during movement
What are discs and menisci for in joints? how are their blood and nerve supply?
weight bearing and shock absorption
blood and nerve supply to outer third
special feature of bursae?
may communicate with joint cavity/risk of infection spreading
characteristics of stable vs. mobile joints
congruent vs. incongruent articular surfaces
limited vs. increase ROM
tight vs. lax capsules/ligaments
4 main joints of the shoulder complex?
sternoclavicular
acromioclavicular
scapulothoracic
gleno-humeral
When do long bones ossify?
in utero at 8 weeks from transition from embryo to fetus
when do epiphyses appear?
generally after birth but if large baby could be before birth
What do the following humeral fractures endanger?
- surgical neck
- midshaft
- supracondylar
- axillary nerve
- radial nerve
- median nerve and brachial artery
difference between anatomical and surgical neck?
anatomical is end of capsule
surgical is common site of fracture
What is the point of the acromioclavicular joint?
give the shoulder girdle a ‘hinge’ to allow for scapulo-humeral rhythm and allow scapula to move along posterior chest well.
likely site of clavicle fracture?
max change of curvature between lateral 1/3 and medial 2/3
Key features of sternoclavicular joint? 3 things
intra-articular disc
strong capsule
costoclavicular ligament to limit movement
what does a intra-articular disc in the sternoclavicular joint do?
increases complexity of movement
lateral disc: elevation depression
medial disc: rotation about longitudinal axis
structures endangered during a sternoclavicular subluxation?
subclavian artery and vein
What are the coracoclavicular ligaments?
ligaments from coracoid process to clavicle: main stabilizers of acromioclavicular joint
prevent upward displacement of clavicle
what does the acromioclavicular ligament do?
prevent upward displacement of clavicle
acromioclavicular joint is strong or weak capsule?
weak
acromioclavicular subluxation grade 1,2,3?
1: stretched not torn
2. separation and AC ligaments torn
3. wide separation AC and coracoclavicular ligaments torn
5 layers of GH joint?
bones labrum capsule tendons/rotator cuff coraco-acromial ligaments/bursae
where does the capsule attach above and below the head of the humerus?
above: anatomical neck
below: surgical neck (makes pouch for increased ROM)
rotator cuff attachment blends into?
capsule
what happens if rotator cuff weak?
deltoid pull humerus upwards and lead to impingment of supraspinatus
what does the subacromial bursa do?
protects head of humerus from hitting acromion
subacromial bursa communicates?
Nope.
shoulder dislocation most common one is?
anterior-inferiorly
how would a posterior shoulder dislocation happen?
electric shock
epileptic fit
how to test if axillary nerve damaged by dislocation?
C5 dermatomes sensory test however it’s not perfect as peripheral nerves often overlap
2 types of synovial joints of the elbow are?
hinge
pivot
elbow complex has two joints, how many synovial cavities?
one
capitulum vs. trochlea is where?
capitulum: lateral
trochlea: medial
What is in the fossae of distal humerus?
fat pads
what is the coronoid process?
part of the proximal ulnar that articulates with humerus
what can be mistaken for a fracture on x-ray?
epiphyses -usually straight rather than jagged fracture
3 main ligaments of elbow
lateral/radial collateral lig
medial/ulnar collateral lig
annular lig
what allows pronation and supination
the LCL attaches to annular ligament rather than a bone
what do the collateral ligaments resist in the elbow
abduction and adduction
max stability in elbow when?
full extension
what is the significance of carrying angle in elbow?
valgus could irritate ulnar nerve
where are the traction epiphyses in the distal humerus?
epicondyles
purpose of interosseus membrane?
allow pron/sup
transmit forces
attachment of muscles
What does the inferior RU joint have?
triangular fibrocartilage complex (disc)
in a ‘ring’ principle of bones what happens?
a fracture in one is associated with fracture in another
what does the distal RU joint disc do? what happens with age?
stabilizes the joint
more perforated with age
annular ligament in children is?
weaker more likely to dislocate with traction on extended arm
what is most common dislocation/fracture in elbow?
posterior dislocation with coronoid process fracture
whats the risk of a supracondylar fracture?
children more commonly damage brachial artery get Volkmann’s ischemia and avascular necrosis of forearm muscles
what is suceptible to injury in medial epicondyle fracture?
ulnar nerve
