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shoulder functional anatomy pt 2 - Coggle Diagram
shoulder functional anatomy pt 2
anatomy of SS and clin sig
-two muscle bellies, anterior and post
-ant is larger and pulls through smaller tendon area
-anterior tendon stress sig greater than post
-RC tendon repairs should inc ant tendon when possible as it acts as primary cont unit
Role of long head of biceps
-opinions vary considerably. vestigial vs crucial role in stability
-EMG/dynamic cadaveric studies show it may contribute to anterior stability by decreasing translation
-may have HH depressing effect in presence of larger RC tear by restraining sup migration
-elbow flexion strength dec as much as 30% with LH tendon tear
-supination can dec by as much as 10-20%
-abduction strength may dec 20% secondary to loss of stabiliizing function
Role of bicipital groove in ant shoulder pain:
-pos assoc b/w radiographic deg changes of bicipital groove and anterosuperior shoulder pain
-inc incidence of bicipital tendon disease in pts with degenerative changes in bicipital groove
-degen changes include stenosis and osteophyte formation
most common variations of labral origin of biceps anchor
-40-60% from supraglenoid tubercle, remaining from superior glenoid labrum
considerable variability in attachment to superior labrum: most common to least common
-equal contribution of ant and post attachment
-mostly post, small contribution to ant labrum
-all post
-mostly ant with little post
quadrangular space: anatomic interval
borders:
-humerus laterally
-long head of triceps medially
-TMi superiorly
-TMa inferiorally
structures:
-axillary nerve and posterior circumflex artery
triangular space: anatomic interval medial to quadrangular space
border:
-lateral: long head of triceps
-superior: TMi
-inferior: TMa
structures:
-circumflex scapular artery (branch of scapular artery)
GH stability: maintained by static and dynamic structures
passive structures: normally lax in mid range
-tighten at extreme ranges to act as checkreins to excessive translation
GH capsule and ligaments
dynamic stabilizer: greatest contribution to stability at mid ranges of motion using concavity-compression effect
-lose effect at end ranges as they are stretched beyond functional length at extremes of motion
primarily RC and deltoid
most important static restraint to ant translation in 90-90 position
-position where most traumatic shoulder dislocations occur
-ant band of IGHL is principal restraint in 90-90 position
-MGHL provides ant translation at mid ranges of shoulder elevation
-SGHL restrains inf translation and ER with arm at side
bankart lesion: lesion of glenoid labrum corresponding to detachment of anchoring point of ant band of IGHL and MGHL from glenoid rim
-result of traumatic dislocation of GH joint
HAGL lesion: uncommon avulsion of humeral attachment of GH ligament bc of GH dislocation
-analogous to more common avulsion of glenoid attachment of GH lig (bankart lesion)