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):
Levator scapulae and rhomboids

Depression (scapula):
Latissimus dorsi
Shoulder Movements

Abduction (scapula):
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:
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:
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:
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
 Infraspinatus
 Teres minor
 Subscapularis

S
I
T
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: