Shoulder Complex & Scapula Flashcards
Sternoclavicular Joint (SC)
Degrees of Freedom: 3
Movements: elevation, depression, protraction, retraction, posterior rotation, anterior rotation
Ligaments: Interclavicular ligament: runs between the medial ends of the clavicles and over the manubrium; strengthens the superior aspect of SC joint; becomes tense when lateral end of clavicle is depressed (ie, when carrying heavy objects)
Anterior sternoclavicular ligament: runs from anterosuperior surface of medial portion of clavicle to anterosuperior surface of manubrium, & adjacent part of first costal cartilage; stabilizes the anterior aspect of SC joint
Posterior sternoclavicular ligament: spans the posterior aspect of the SC joint surfaces; weaker than its anterior counterpart
Costoclavicular ligament: runs between superior surface of 1st rib & inferomedial aspect of clavicle; stabilizes inferior aspect of SCJ - limits clavicular elevation & anteroposterior movement
Scapula Thoracic Joint (costal)
Degrees of Freedom: 3
Motions are a combo of SC & AC joints
Movements:
Gliding: elevation, depression, abduction, adduction
Rotation: internal, external, upward, downward
Tilt: anterior, posterior
Ligaments:
No ligaments; stabilized by synchronized actions and passive tensions of the traps, serratus anterior, rhomboids, and levator scapulae
Acromioclavicular (AC)
Degrees of Freedom: 3
Movements: anterior and posterior gliding, superior and inferior gliding
Ligaments: Superior Acromioclavicular ligament: connects superior aspect of clavicle and acromion; fuses partly with trapezius, which helps to support the AC joint
Inferior Acromioclavicular ligament: connects the inferior surfaces of acromion and clavicle; thinner than its counterpart and can perforate with age; particularly important for people with noncongruent articular surfaces of AC joint b/c it provides an attachment point for articular disc if it’s present
Coracoacromial ligament: extends between the acromion and coracoid process; forms a roof over the proximal humerus, known as the coracoacromial arch
Suprascapular ligament: bridges across suprascapular notch, allows for passage of suprascapular nerve
Coracoclavicular ligament: runs from crest of coracoid process to the clavicle; helps to prevent shoulder separation
Glenohumeral (GH)
Degrees of Freedom: 3
Movements: flexion, extension, abduction, adduction, internal rotation, external rotation, horizontal abduction, horizontal adduction
Ligaments: Glenohumeral ligaments (superior, middle, and inferior): thickened region of joint capsule; support the GHJ from the anteroinferior side; weak stabilizers; limit maximum amplitude of certain arm movements; become taut during external rotation of humerus, relax in internal rotation; resist anterior translation of humeral head; middle and inferior ligaments tense during abduction, while the superior is relaxed
Superior glenohumeral ligament: w/ the coracohumeral ligament, supports rotator interval and prevents inferior translation of the humeral head, particularly during shoulder adduction; runs from supraglenoid tubercle of scapula to prox aspect of lesser tubercle of humerus
middle glenohumeral ligament: stabilizes anterior capsule, limiting external rotation, particularly when in abduction
inferior glenohumeral ligament: stabilizes the humeral head when abducted above 90 degrees; anterior band limits ER, posterior band limits IR; strongest of the three GHJ ligaments; runs between the glenoid labrum and the infromedial part of the humeral neck
Transverse humeral ligament: runs between the tubercles of the humerus; prevents displacement of the tendon from the sulcus
Coracohumeral ligament: runs between the coracoid process of scap to the tubercles of the humerus; supports GHJ from superior side; limits inferior translation & excessive external rotation of the humerus
Scapular Protraction
(abduction w/anterior tilt)
-Agonist:
-serratus anterior (w/ fixed origin)
-pectoralis minor (w/ fixed origin)
Scapular Retraction (adduction w/posterior tilt)
-Agonist:
-trapezius (middle fibers)
-rhomboid major
-rhomboid minor
Scapular Elevation
-Agonist:
-trapezius (upper fibers,
unilaterally)
-rhomboid major
-rhomboid minor
-levator scapulae (unilaterally)
Scapular Depression
-Agonist:
-trapezius (lower fibers)
-serratus anterior (w/ fixed origin)
-pectoralis minor
Upward Scapular Rotation
-Agonist:
-trapezius (upper & lower fibers)
-serratus anterior (w/ fixed origin)
Downward Scapular Rotation
-Agonist:
-trapezius (upper fibers, unilaterally)
-rhomboid major
-rhomboid minor
-levator scapulae
-pectoralis minor
Shoulder Flexion
-Agonist
-deltoid (anterior fibers)
-pectoralis major (clavicular fibers)
-biceps brachii
-coracobrachialis
Shoulder Extension
-Agonist:
-deltoid (posterior fibers)
-latissimus dorsi
-teres major
-pectoralis major (sternal fibers)
-triceps brachii (long head)
Shoulder Abduction
-Agonist:
-deltoid (all fibers)
-supraspinatus
Shoulder Adduction
-Agonist:
-latissimus dorsi
-teres major
-teres minor
-infraspinatus
-pectoralis major (all fibers)
-triceps brachii (long head)
-coracobrachialis
Shoulder Horizontal Abduction
-Agonist:
-deltoid (posterior fibers)
