Shoulder Girdle

Shoulder girdle

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consists of three synovial articulations

1. GLENOHUMERAL (GH) joint
2. STERNOCLAVICULAR (SC) joint
3. ACROMIOCLAVICULAR (AC) joint

and a fourth “functional” articulation, the SCAPULOTHORACIC joint, which is not a true anatomical joint

• Scapulothoracic movements
• Scapulohumeral rhythm

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Muscles of the shoulder girdle

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Summary of shoulder girdle movements during shoulder elevation “Shoulder elevation” or “elevation of the arm” (Smith, Weiss, & Lehmkuhl, 1996, p. 235) refers to a combination of movements that place the glenohumeral joint in either full flexion or abduction. Elevation involves glenohumeral movement in combination with scapulothoracic movement and thoracic extension.

From: http://moon.ouhsc.edu/dthompso/namics/shoulder.htm

Shoulder Girdle

Bones

• 2 clavicles (acromial extremity, conoid tubercle, body, costal tuberosity, sternal extremity)

• 2 scapula (a – anterior side, b – posterior side)

Joints

• Glenohumeral – humerus articulating with glenoid fossa of scapula
• Sternoclavicular (SC) – proximal clavicle articulating with manubrium and cartilage of rib 1
• Acromioclavicular (AC) – acromian process of scapula articulating with distal clavicle
• Coracoclavicular – coracoid process of scapula articulating with inferior clavicle
• Scapulothoracic – anterior scapula articulating with thoracic wall

Movements of Scapula and Muscles Causing Movement:

• Protraction (scapular abduction) – serratus anterior, pectoralis minor
• Retraction (scapular adduction) – trapezius, rhomboid, levator scapulae
• Downward Rotation – rhomboids, pectoralis minor
• Upward rotation – trapezius, serratus anterior
• Depression – trapezius (lower), pectoralis minor, subclavius
• Elevation – trapezius (upper), levatro scapulae, rhomboid

Scpulohumeral Rhythm- a regular pattern of scapular rotation that accompanies and facilitates humeral abduction
        *beyond 30 degrees abduction, 1 degree scapular rotation for 2 degrees of humerus elevationMuscles (all have origins on axial skeleton with insertions on scapula or clavicle)

Muscle	Origin	Insertion	Action	Palpate
Trapezius	occipital, C7-T12	posterior clavicle, acromian process, scapular spine	elevate scapula, extend head, upward rotation, adduction, depression	up and down posterior neck to T12, spine to scapula
Levator Scapulae	C1-C4	medial border of scapula above spine	elevate scapula	deep to trapezius
Rhomboid	C7-T5	medial scapula below spine	elevate and retract scapula	deep to trapezius
Serratus Anterior	upper 9 ribs	anterior border of scapula	protraction and upward rotation	front and lateral chest
Pectoralis Minor	ribs 3-5	coracoid process	protraction, downward rotation, depression	under pectoralis major
Subclavius	rib 1	“subclavian” groove of clavicle	depression	not palpable

From: http://academic.wsc.edu/faculty/jatodd1/351/ch7outline.html