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Shoulder Functional anatomy Pt 4 - Coggle Diagram
Shoulder Functional anatomy Pt 4
-center of rotation in normal GH: center of GH head at mid glenoid level
-severely RC deficient GH: CoR migrates superior secondary to unopposed pull of deltoid and loss of HH depressing function. HH migrates sup and medial
-when HH no longer centered in glenoid, deltoid is at mechanical disadvantage resulting in limited abduction
coracoacromial ligament anatomic variations include
-quadrangular (48%)
-Y shape (42%)
-broader lateral, thinner medial band
-broad banded (8%)
-multiple bands (2%)
arthroscopic acromioplasty
-acromial attachment of coracoacromial ligament is released in most cases
-CA lig can be an impinging factor and is often calcified or has enthesopathy contributing to anterior acromial spur formation
-overlying deltoid inserting into ant part of acromion remains attached
most common normal variations in labral anatomy
1) presence of sublabral foramen: sulcus b/w well-developed anterosuperior portion of labrum and glenoid art cartilage
2) presence of sublabral foramen and cord-like MGHL
3) complete absence of labral tissue at the anterosuperior aspect of the labrum in association with cordlike MGHL attached to superior part of the labrum at base of the biceps (Buford complex)
pec major tendon anatomy
-width of insertion ~6 cm
-insertion is broad on undersurface, small on anterior surface
-sternal head spirals into its insertion to form posterior lamina
-clavicular head remains anterior as it inserts into humerus to form anterior lamina
medial pectoral nerve enters pec major ~12 cm from lateral insertion and 2 cm from inferior edge
-insertion is inferior to lateral nerve insertion
lateral pectoral nerve inserts ~12.5 cm from lateral humeral insertion
-passes medial to pec minor before entering pec major whereas medial pec nerve passes through or lateral to pec minor before entering pec major
anatomy of deltoid insertion
-ant, middle, and post deltoid insert in a v-shaped tendinous confluence
-broad post band and narrow separate ant band
-ant band accounts of 1/5 of insertion
-insertion can be really close to pec major insertion, nearly apposed to each other in some cases
-avg distance from axillary nerve is 5.6 cm anteriorly, 4.5 cm post
main stabilizers of AC joint
-AC ligament and joint capsule primary constraints for post displacement of clavicle and post axial rotation
-conoid lig primary role in constraining ant/sup rotation and ant/sup displacement of clavicle
-trapezoid lig acts as constraint for both horizontal and vertical displacement primarily when clavicle moves in axial compression toward acromion
avg proximal articular version relative to trans epicondylar axis of distal humerus: 30 deg of retroversion
normal version/tilt angle of glenoid: 8 deg retroversion
-clinical sig is inc retroversion places pt at inc risk for post instability
relationship b/w glenoid inclination and RC tears/instability: yes
increasing superior inclination of glenoid sig reduces force required for sup head migration
-suggests more upward facing glenoid may increase risk for superior HH translation > contributes to development of RC disease
-inc glenoid retroversion shown to inc risk for post instability