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Shoulder Functional Anatomy Ch. 37 - Coggle Diagram
Shoulder Functional Anatomy Ch. 37
Muscle Origin, Insertion, action, Innervation Chat Pg 321.
Normal Scapulohumeral Rhythm:
relative Gh: ST movement varies from 1.25:1 to 4.3:1
-avg is 2:1
Giding movements of shoulder:
-obligate translation of head occurs due to asymm. tighterning of CL structures
-obligate anterior translation anteriorly >55 deg forward elevation
-obligate post translation with extension >35 deg
-surgical tightening of RI or post capsule inc ant translation with FE
-excessively tight anterior instability repairs shift humeral head posteriorly
tightness in one direction can lead to instability in the opposite direction
During elevation HH shifts superiorly 3 mm and rotates in place
strength ratios of shoulder
IR:ER-3:2
add:abd-2:1
ext:flex-5:4
-women ~45-65% strength of men
Coracohumeral ligament
-limits ER with arm at side
-arises from lateral aspect of coracoid process and inserts in RI
-frequently thickened and contracted in frozen shoulder
Rotator Interval (RI): capsular tissue interval b/w subscap and supra
components:
-parts of tendons of subscap and supra
-coracohumeral lig
-SGHL
-structures limit inf translation and ER with arm adducted
-limit post translation when arm is flexed, add, and IR
medial portion limits inf>ER, lateral limits ER>inf trans
-pathologic RI sig limits ER, especially in AC
-deficient or attenuated RI may be associated
parts of prox humerus
greater tuberosity
lesser tuberosity
shaft
articular/head segment
these are 4 ossification centers of humerus
-common sites of fracture especially in older adults with osetopenic bone
form basis of neer classification of prox humeral fx
shaft attaches to prox humerus at surgical neck
anatomic neck is above tuberosities v/w articular margin and art capsule
GT has 3 facets for RC attachments (SS, IS, TMi)
-LT for subscap
Layers of RC:
-5 layers in sup aspect of RC/capsule
-variations in tissue properties and loads of layers may contribute to shear forces > RC tears
at bursal surface
layer 1: superficial portion of CH lig
layer 2: closely packed parallel bundles of collagen fibers from mm belly to GT
Layer 3: smaller fascicles and more random orientation
Layer 4: loose CT and bands of collagen that run perpendicular to longitudinal orientation of cuff tendon
-also contains deep extent of CH lig and transverse band that may function to distribute forces along RC insertion
layer 5: true capsular layer
BM functions of RC:
-stability through force couples
-aids in motion about the GH joint
-HH depressing effect to counter sup pull of deltoid
-acts multiaxially during motion to maintain proper position of HH in glenoid