lecture 7: Shoulder and Elbow Flashcards
What are the features that permit a wide range of motion for the shoulder joint? (LO1)
the articular surface of the humerus head is considerably larger than the glenoid fossa
what is the common site of fracture in the head of the humerus?
surgical neck
what is the name of the structure around the glenoid fossa that softens and deepens its edge?
glenoid labrum
what muscles originate at the supraglenoid and infra glenoid tubercles?
supraglenoid tubercle- ‘O’ of the long head of bicep brachii
infra glenoid tubercle- ‘O’ of the long head of triceps
what are the rotator cuff muscles?
subscapularis, teres minor, supraspinatus, and infraspinatus
what ligament reinforces the shoulder joint capsule superiorly?
coracohumeral
where do most shoulder dislocations happen?
anteriorly and inferiorly
which ligament holds down the tendon of the long head of the bicep?
traverse humeral ligament
what is the role of
what are the chief abductors of the shoulder?
Supraspinatus and deltoid(multipennate central fibres)
which muscle prevents upward displacement of the head of the humerus?
teres minor and major
what is the chief lateral rotator of the shoulder
infraspinatus
teres minor
Posterior deltoid
what are the chief internal rotators(and adductors)?
subscapularis
pectoralis major
teres major
Latissimus dorsi
what muscles flex the arm on the shoulder?
clavicular fibres of pec major
anterior fibers of deltoid
what muscles extend the arm at the shoulder joint?
posterior fibers of deltoid latissimus dorsi
Teres major
Long head of triceps
Steenocostal portion of pectoralis major
what is the weakest position of the shoulder joint
when the arm is abducted only the tendon of the long head of the triceps(which originates at the infra glenoid tubercle) is supporting the head of the humerus inferiorly.
e.g fall on extended arm
‘O’ and ‘I’ of infraspinatus, supraspinatus, and teres minor
infraspinatus:
‘O’-infraspinous fossa
‘I’-middle facet of greater tubercle
Supraspinatus:
‘O’-supraspinous fossa
‘I’-superior facet of greater tubercle
Teres minor:
‘O’-lateral border of scapula
‘I’-inferior faceet of greater tubercle
‘O’ and ‘I’ subscapularis
O:Subscapular fossa
I:lesser tubercle of humerus
what nerve innervates teres minor?
axillary n
what nerve innervates infraspinatus and supraspinatus?
subscapular nerve
what nerve innervates subscapularis?
upper&lower subscapular n
what is the action of the subscapularis
internally rotates the arm
main function of supraspinatus
abduct the arm
main function of infraspinatus and teres minor
externally rotate arm
subscapularis: ant or post?
anterior
what nerve innervates teres major?
lower subscapular nerve
what is the order of insertions on the intertubercular groove?
most lateral-pec major
middle-lat.dorsi
most medial- teres major
what are the bursas in the shoulder?
-subscapular bursa(lies under subscapularis tendon)
-subcoracoid bursa( under coracoid)
-subacromial bursa and subdeltoid bursa(continuation of each other)
what provides active stabilisation of the shoulder ?
rotator cuff muscles
what muscles are innervated by the suprascapular nerve?
supraspinatus, infraspinatus
what does the subscapular nerve innervate?
subscapularis
what are the flexor/extensor joints of the elbow?
Humero-ulnar joint
Humero-radial joint
what are the pronator/supinator joints of the elbow?
humero-radial
superior radio-ulnar joint
what is the area on the condyle that is part of the humero-ulnar joint?
trochlea
what are the components of the humero-radial joint?
capitulum
superior surface of radius
what is the function of the coronoid, olecranon, and radial fossas in the elbow?
increase the range of motion at the maximum flexion
what is the role of ulnar and radial collateral ligaments in the elbow?
Ulnar prevent abduction of Ulna and Radial prevents adduction of radius
where does the radial collateral ligament originate and insert?
O- lateral epicondyle
I- anular ligament of radius
what is the role of anular ligament of radius?
runs from edge of radial notch, wraps around the head of the radius
allows the radius to rotate BUT prevents it from being pulled out inferiorly
what is the function of the fat pads in the elbow?
Sit in the coronoid and olecranon fossas, reduce the amount of synovial fluid needed. Moved away during flexion.
what happens if yank on a kid’s arm too hard?
can pull the head of the radius through the anular ligament
(because it takes a while to ossify)
can pop it back in
in adults- ossified and ligament is tough, so can cause more damage
what is wrong here?
can see that the fat pads have moved out of the fossas
potential fracture leaking blood into the joint space-> lifting the fat pads
arm abductors at the shoulder joint
supraspinatus
deltoid middle part
arm adductors at the shoulder joint
arm flexors at the shoulder joint
arm extensors at the shoulder joint
internal and external rotators of the arm
internal:
lat. dorsi
teres major
pec. major
subscapularis
anterior deltoid
external:
teres minor
posterior deltoid
infraspinatus
