Lecture 6 - Shoulder Function Flashcards
functions of the shoulder girdle
- > the shoulder girdle is the main point of attachment of the upper-limb to the axial skeleton
- > also is very mobile and is esential for a variety of tasks and all uper limb functional activities
superior glenohumeral ligament limits which movements
- > ant displacement of humeral head
- > inferior and some posterior translation
middle glenohumeral ligament limits which motions
- > anterior displacement of humeral head
- > external rotation
inferior glenohumeral ligament prevents which motions
anterior displacement of humeral head
- > inferior translation and some posterior translation
coracohumeral ligament prevents which motions
- > resists inferior and posterior translation
what direction most commonly results in a dislocated shoulder
a downward and anterior motion
changes in the position of the humeral head or the position of glenoid fossa can…….
significantly impact function of the shoulder and increase the risk of injury
factors that can alter the position of the humeral head and glenoid foss
Muscle imbalances
- > weak muscles
- > tight structures
- > posture
Instability
- > ligament laxity
- > injury
Loss of neural control
- > impacting dynamic stability
dynamic stabilizers role in the shoulder joint
the shoulder joint can’t be fully secured to the glenoid cavity as it has to move so dynamic stabilizers must compensate for this to help hold the humeral head in the glenoid fossa
- > the rotator cuff muscles provide this dynamic stability
which is stronger: internal or external rotators? Why?
internal rotators
- > they are able to produce more force than ER due to overall greater cross-sectional area of the internal rotators
*their ability to generate more force is very useful in high speed throwing*
which muscles will ideally position the glenoid fossa during upward rotation of the scapula
upward rotators of the scapula
- > upper and lower fibres of trapezius
- > serratus anterior
Structures that produce a passive restraint against shoulder movement
Ligaments
Posture and muscle imbalance
structures that will passively restrain sternoclavicular joint
- > interclavicular ligament
- > costoclavicular ligament
- > sternoclavicular ligaments (post and ant)
structures that will passively restrain acromioclavicular joint
- > acromioclavicular ligaments
- > coracoclavicular ligaments
structures that will passively restrain the glenohumeral joint
- > coracohumeral ligaments
- > glenohumeral ligaments (Sup, Mid, Inf)
structures that limit shoulder flexion
Ligaments
- > post. part of coracohumeral ligament
- > trapezoid ligament
- > post. part of joint capsule GHjt
Muscles
- > rhomboids
- > levator scapulae
- > infraspinatus
- > teres minor and major
- > ticeps
- > lattiss
- > Post Deltoid
structures that limit shoulder extension
Ligaments
- > ant part of coracohumal lig
- > APO joint capsule GHjt
- > all parts of the glenohumeral joint ligs
Muscles
- > pec major
- > biceps
- > ant deltoid
- > coracobrachialis
structures that limit shoulder abduction
Ligaments
- > mid and iferior glenohumeral lig
- > trap lig
- > inf part of the capsule GHjt
Muscles
- > rhomboids
- > lev scap
- > coracobrachialis
- > pec major
- > lats
- > teres major
- > subscapularis
structures that limit adduction
body gets in the way; gravity does the work
structures that limit medial/internal rotation
ligaments
- > posterior glenohumeral joint capsule
muscles
- > infraspinatus
- > teres minor
structures that limit lateral/external rotation
ligaments
- > ant. glenohumeral joint capsule
- > glenhum ligaments (esp. middle portion)
- > coracohumeral ligaments
Muscles
- > pec major
- > lats
- > teres major
- > subscapularis
shoulder conditions
Instabilty
- > glenoid labrum injury
- > dislocation and subluxation
Impingement or Tendinopathy
- > scapular control
- > humeral head position
how does anterior dislocation of the shoulder occur
- > arm is forced into excessive abduction and external rotation
*most common traumatic sports injury*
damage caused by anterior shoulder dislocation
- > damage to glenoid labrum’s attachment to anterior glenoid margin
- > ligament damage
- > damage to auxillary nerve
*impaired sensation in lat side of arm and impairment of teres minor and delt
what is a labral tear/ tear to glenoid labrum
- > the glenoid labrum serves as an attachment site for shoulder capsule which can be damaged/torn due to repeated overhead throwing or trauma
how does the position of the glenoid cause shoulder impingement
- > caused by poor scapular control when performing arm movements,
- > the poor movement of the scapula during movement doesn’t allow for the glenhum joint to be in ideal position
tendinopathy
tendons become inflamed due to overuse or repetitive impingement
most commonly ruptured tendon
supraspinatus tendon rupture
biceps
what causes shoulder impingement
occurs when theres an imbalance between muscles that support the humeral head
- > rotator cuff muscles
- > external rotators vs internal rotators
