SHOULDER COMPLEX

Extrinsic Shoulder Muscles Review the following: Pectoralis major Pectoralis minor Serratus anterior Trapezius complex Latissimus dorsi Levator scapulae Rhomboideus major Rhomboideus minor

Sensory Supply to Shoulder Supraclavicular nerves: From cervical plexus C3-4 Supply skin over clavicle and over the superior-lateral aspect of pectoralis major Cutaneous branches of dorsal rami: Penetrate deep and superficial back muscles Supply skin on either side of midline of back

Shoulder Movements Elevation (scapula): Depression (scapula): Levator scapulae and rhomboids Depression (scapula): Latissimus dorsi

Shoulder Movements Abduction (scapula): Abduction (shoulder): Serratus anterior Abduction (shoulder): Middle deltoid Biceps brachii assists Adduction (scapula): Middle trapezius Adduction (shoulder): Pectoralis major (clav) Latissimus dorsi

Shoulder Movements Upward rotation (scapula): Serratus anterior Upper and lower trapezius (force couple) Downward rotation (scapula): Rhomboids Levator scapulae

Quadrilateral Space Boundaries: Contents: Inferior glenohumeral capsule. Teres major. Triceps longus. Surgical neck of humerus. Contents: Axillary nerve. Posterior circumflex humeral artery.

Shoulder Complex Joints Sternoclavicular joint (SC) Acromioclavicular joint (AC) Glenohumeral joint (GH)

Sternoclavicular Joint (SC) Plane synovial joint Articulating surfaces: Sternal end of clavicle Articular notch on manubrium First costal cartilage 3 degrees of freedom

SC Joint Movements Elevation and depression: Occurs around AP axis Elevation = 45 degrees Depression = 15 degrees Protraction and retraction: Occurs around vertical axis Protraction ROM = 15 degrees Retraction ROM = 15 degrees Rotation: Occurs around transverse axis

Sternoclavicular Joint Joint disc Fibrocartilage meniscus Attached to: Clavicle inferiorly Manubrium and first costal cartilage inferiorly Ligaments: Anterior/posterior sternoclavicular ligaments: Check anterior/posterior movements of clavicular head.

SC Joint Ligaments Costoclavicular ligament: Interclavicular Axis for elevation and depression Axis for protraction and retraction Main check for elevation Interclavicular

Acromioclavicular Joint Plane synovial joint 3 degrees of freedom Articulation surfaces: Convex facet on lateral end of clavicle Concave facet on acromion

AC Joint Movements Scapular rotation: Occurs around AP axis. Winging of vertebral border of scapula: Occurs around vertical axis. Tipping of inferior angle of scapula: Occurs around coronal axis.

Acromioclavicular Joint Acromioclavicular ligaments: Superior and inferior Reinforce joint capsule Coracoclavicular: Trapezoid (lateral) Conoid (medial)

Glenohumeral Joint Ball-and-socket joint Synovial Components: Head of humerus Glenoid fossa of scapula Glenoid labrum Fibrocartilage meniscus Deepens articulating surface of glenoid fossa

Glenohumeral Joint Ligaments: Joint capsule: Glenohumeral Coracohumeral Coracoacromial Joint capsule: Very lax Up to an inch of passive distraction

GH Joint Movements Flexion/extension of brachium: Abduction/adduction of brachium: Lateral/medial rotation of brachium:

Shoulder Complex Components Scapulothoracic joint: Not a true anatomic joint Represented by sliding of scapula on thoracic cage Coracoacromial arch: Components: Acromion Coracoid process Coracoacromial ligament Subacromial/subdeltoid bursae

ROTATOR CUFF

Rotator Cuff Composed of four muscles whose tendons of insertion form a partial “cuff” around the head of the humerus. Involved in snubbing and rotating head of humerus

Rotator Cuff Components Supraspinatus S Infraspinatus I Teres minor T Subscapularis S

Rotator Cuff

Rotator Cuff

Scapulohumeral Rhythm Refers to relatively uninterrupted movement of upper extremity from dependent position to full abduction. Requires simultaneous and coordinated movements of all the previous-named joints.

Scapulohumeral Rhythm ROM: Full abduction: 180 degrees Contributed by glenohumeral joint: 120 degrees Contributed by scapulothoracic movement: 60 degrees: Sternoclavicular joint = 40 degrees Acromioclavicular joint = 20 degrees Ratio of GH to ST = 2:1

Steps in Arm Abduction Movement (searching) of scapula: Serratus anterior clamps scapula to thoracic wall Snubbing of head of humerus into glenoid fossa: Rotator cuff muscles First few degrees of abduction: Supraspinatus External rotation of humerus: Infraspinatus

Clinical Applications Deltoid paralysis: Axillary nerve Serratus anterior paralysis: Long thoracic nerve Tears in rotator cuff Supraspinatus most often torn: