Shoulder Complex Flashcards
4 Joints that make up shoulder complex
GH, SC, AC, ST Joints
True Joints
GH, AC, SC Joints
Functional Joint (not a true “joint”)
ST “joint”
Dynamic Stabilization
-active forces or dynamic muscular control
What type of joint is the Sternoclavicular (SC) joint?
-Synovial with 3 DOF;
-Saddle-shaped;
-Reciprocal convex-concave surfaces
SC fibrocartilage disc
-Improves stability
-Increase congruence between the articulating surfaces and dissipates joint loads
A/P SC Ligaments
-Reinforces capsule
-Restraint A/P translations
SC-Costoclavicular Ligament (A/P laminae)
-Limit lateral elevation and medial translation of clavicle
-Absorb and transmits superior forces
SC-Interclavicular Ligament
-Limits excessive depression of lateral clavicle
-Limits superior gliding of medial clavicle
Interclavicular ligament protect?
-Brachial plexus and subclavian artery
Joint connecting UE to axial skeleton?
-SC Joint
Coracoclavicular Ligament Critical Function
-Couple posterior rotation of the clavicle + upward rotation of scapula
Resting position of scapula
-Approx. 5cm from midline
-Betw. ribs 2-7
-Tilted ant. 10-15 degrees from vertical
-Up. rotated 10-15 degrees from vertical
-IR 34-45 degrees from coronal plane
SC Open-packed position
-arm resting by the side
SC Close-packed position
-Max UE elevation
SC Osteokinematics
Elevation/Depression
Protraction/Retraction
A/P Rotation
Subacromial Space structures
-Rotator cuff tendons
-LH of biceps tendon
-Subacromial bursae
Coracoacromial arch (Osteoligamentous vault over humeral head) Consists of…
coracoid process
acromion
coracoacromial ligament
AC joint
ST “joint” Functions
-Orient contact of scapula with thorax, glenoid fossa with humeral head
-Provide stable base for controlled motions between humeral head and glenoid fossa
-Add range to elevation of arm
Muscles Synergistically Stabilizing GH joint
-Rotator cuff muscles + Deltoid
Full elevation of arm, ST “joint” needs to
-Up. rotate, post. tilt, and ER to open subacromial space
The upper trap, serratus anterior, and lower trap fire _______________ to produce scapular upward rotation while the rhomboids fire ______________ to stabilize this motion.
-concentrically; eccentrically
What type of joint is the Acromioclavicular (AC) Joint?
-Incongruent Plane synovial w/ 3 DOF
Primary function of the AC Joint
-allow scapula to rotate in 3D; increasing UE motion, positions glenoid beneath humeral head, max scapula contact with thorax
AC Osteokinematics
IR/ER
A/P Tilting
Up/Down Rotation
AC Open packed position
Arm resting by side
AC Close-Packed position
90 degrees ABd.
AC superior and inferior ligaments
-assist capsule in apposing the articular surfaces
-provide horizontal stability and prevent superior dislocation of the AC joint