Shoulder complex Flashcards
What are the joints contributing to the shoulder complex
Acromioclavicular (AC)
Sternoclavicular (SC)
Scapulothoracic (ST)
Glenohumeral (GH)
what are the bones contributing to the shoulder comple
Scapula
clavicle
humerus
sternum
Describe the glenoid fossa and its orientation in good posture
-small and shallow
-diected anterior-laterally about 5*
-glenoid labrum and articular cartilage add depth
(articular cartilage is thinner on the inside)
What is the resting position of the scapula
-superior angle at T2
-root at T3
-inferior angle T8
-Medial border 5-6cm from midline
-35* anterior to frontal plane
describe the orientation of the clavicle
-acts as a strut-keeps scapula at a constance distance from trunk/thoracic
-20* posterior to the frontal plane
Describe the orientation of the humerus
-head faces medial
-incline 135* to shaft (superiorly)
-retroverted 30* posteriorly
articular surfaces of the GH joint
head of hummus with glenoid fossa of scapula
(1/3 of the humeral head contacts the glenoid fossa at any given time)
What is hilton’s law
a joint capsule has nerve supply from branches of the nerves that cross that joint (innervate the muscles that cross that joint)
Describe the GH
-capsule innervation
-overall ligament structure
-capsule is innervated by C5,6
-has a lax structure to allow for large ROM
~arm at side causes an inferior fold/slack
~can be distracted about 1 in
GH ligaments
coracohumeral
glenohumeral (Superior, middle, and inferior)
Coracohumeral ligament
-coracoid process to greater tuberosity
-limites external rotation and inferior translation (when you pull down on the humerus)
-limits flexion and extension at the extremes
Superior Glenohumeral ligement
Runs under coracohumeral
limits inferior translation
-limits external rotation at 0 degrees (what my arm is at my side)
Middle glenohumeral ligament limits
-limits external rotation at 0 and 45 * of abduction
Inferior GH ligament
-thickest
-2-3bands of the ligament
~superior (“2-4 O’clock”)
~axillary pouch
~posterior (“7-9 o’clock”)
-ligament is like a sling for the humerus
-limits ER at 90* of abduction/prevents anterior translation
-limits IR at 90* of abduction/prevents
posterior translation
GH capsule/ligament influence on kinematics
-ER produced posterior translation
-IR produced anterior translation
-capsule tension counters and reverses humeral head movement
where are the GH joint bursae
-subscapular bursa: deep to tendon of subscapularis
-subacromial bursa/sub deltoid: in the subscromial space
GH joint classifcation
-diarthrosis
-ball and socket: enarthroses
-triaxial
-three degrees of freedom
what are the osteokinematic motions of the GH joint and ROM
-flexion 0-180
-Abd: 0-180
-external rotation 0-90 (90 when abducted and 0-60 when at side)
-internal rotation 0-65 (90 when Abd)
-horizontal Add 0-120
-horizontal abd 0-45
-extension 0-50