Scapulothoracic Joint
what muscles perform downward rotation?
levator scapulae, rhomboids
True/False: all AC motion occurs within the plane of the scapula
True
what type of joint is the SC joint
Saddle joint
True/False: The rotator cuff muscles consist of, supraspinatus, infraspinatus, teres major & subsapularis
False: teres minor not major!
What are the Thoracohumeral muscles and why are they important?
Latissimus dorsi, pectoralis major
bypass scapula creating a problem
Protraciton with the scapula occurs with what motions?
IR & abduction
what type of joint is the AC joint?
plane synovial joint
what is the function of the articular disc at the SC joint
- Separate the joint into M and L compartments
- Tethered to the costal cartilage and manubrium on the posterior aspect
- Tethered to the clavicle on the superior medial part
- Elevation and depression→ medial end of clavicle and the disc
- Protraction and retraction→ the disc moves with the clavicle (so disc on manubrium)
is the long head of the biceps tendon interarticular or extraarticular?
True/False the radial nerve is off of the posterior cord
True
Serratus Anterior
Upper Trapezius
Lower Trapezius
What is the function of the coracoclavicular ligament?
Stability to the AC joint, hold the lateral end of the clavicle close to the joint
What is the clavicular motion with scapular elevation
lateral clavicle upwardly rotates
What is the rotator cuff interval?
gap between the supraspinatus and subscapularis caused by the coracoid process
What is the scapulohumeral rhythm?
what is the scapular plane?
Scapular plane 30 degrees forward
Glenoid fossa facing 30-40 degrees of anterior to frontal plane
Clavicular is 20 degrees posterior to frontal plane
what are the scapular rotations at the AC joint?
Upward rotation & Downward rotation (AP axis)
IR and ER (vertical axis)
Anterior and posterior tilting (ML axis)
what is the clavicular motion during protraction of the scapula?
Lateral clavicle moves anteriorly on the manubrium and first costal cartilage with up to 15-20 degrees of motion
what is the function of the labrum?
triangular fibrocartilaginous ring that rims the glenoid fossa to improve congruency
Attached to the periphery of the glenoid fossa (rim)
50% increase in the congruency of the glenoid fossa!!!
Continuous with the long head of the biceps brachii
Type 1 collagen fibers - tension
what is the orientation of the scapulothoracic joint
•Internally rotated 35 to 45 degrees
•Anteriorly tilted 10 to 15 degrees
•Vertebral border upwardly rotated 5 to 10 degrees
True/false: motions only happen with combination at SC & AC joint
Motion can only happen w/ a combo of motions at the SC & AC joints. (combined joint motions)
What is the Acromioclavicular Stress?
AC joint is susceptible to both trauma and degenerative changes. Usually occurs in the first three decades of like. Typically due to inferiorly directed forces on the acromion
what shape is the medial clavicle in the frontal & sagittal plane?
Frontal plane: convex
Sagittal plane: concave
what structures make up & pass through the quadrangular space
boundaries: Inferior margin of teres minor, surgical neck of the humerus, superior margin of teres major, lateral margin of long head of triceps brachii
Structures that pass through it: axillary nerve, posterior circumflex humeral artery & vein
What is the coracoacromial arch and what is the importance of it?
Forms an osteoligamentous vault that covers the humeral head and forms a space within which the subacromial bursa, the rotator cuff tendons, and a portion of the tendon of the long head of the biceps brachii.
Roof of the GH joints
TUAT WITH ARM AT SIDE