KINE 3200 - Chapter 4

Scapula and Clavicle

• move as a unit

• clavicle’s articulation w/ sternum is only a bony link to the axial skeleton

Know the bony landmarks

Shoulder Girdle

• upper extremity depends on the shoulder girdle to serve as a base

• ONLY attachment of upper extremity to axial skeleton

Sternoclavicular (SC) Joint

• link between the clavicle & sternum

• multiaxial, arthrodial joint

• Movements: in relation to manubrium, the clavicle moves ~ protraction/retraction, elevation, depression, slight rotary gliding movements

Sternoclavicular (SC) Joint -> Ligamentous support

• anteriorly and posteriorly by the SC ligaments

• Costoclavicular & interclavicular ligaments provide stability

Acromioclavicular (AC) Joint

• joint in the shoulder where 2 bones meet

• Arthrodial classification

• 20º-30º of gliding & rotational motion accompany shoulder girdle & shoulder joint motions

• often injured

Acromioclavicular (AC) Joint -> Ligamentous support

• Coracoclavicular ligaments

• Acromioclavicular ligaments

Scapulothoracic Joint

• Not a true synovial joint, DOESN'T have regular synovial features

• Movement depends on SC & AC joints which allows the scapula to move ~ abduction/adduction ~ upward/downward rotation ~ elevation/depression

• supported dynamically by its muscles

• NO ligamentous support

Movements of shoulder girdle

• SC joint provides a majority of the shoulder girdle movements

• Shoulder girdle = scapula movements

• Where scapula goes, clavicle follows

** Shoulder joint & shoulder girdle work together in carrying out upper extremity activities

Abduction and Adduction

• Abduction: Scapula moves laterally away from spinal column

• Adduction: Scapula moves medially toward spinal column

Downward/Upward Rotation

• Downward rotation: Moving the inferior angle of the scapula inferiorly and medially towards the spinal column

• Upward rotation: Moving inferior angle of the scapula superiorly and laterally away from spinal column

Depression/Elevation

• Depression: Downward or inferior movement of scapula, as in returning to normal position

• Elevation: Upward or superior movement of scapula, as in shrugging shoulders

Shoulder Girdle Movements

• for some movements, scapula must rotate on axis

Internal/External Rotation

Internal Rotation (lateral tilt)

• During abduction, scapula rotates about vertical axis resulting in posterior movement of medial border & anterior movement of lateral border

External rotation (medial tilt)

• During extreme adduction, Scapula rotates about its vertical axis resulting in anterior movement of the medial border & posterior movement of lateral border

Anterior/Posterior Tilt

Anterior/upward tilt

• Rotational movement of scapula about frontal axis during glenohumeral hyperextension

• Superior border moves anteroinferiorly & inferior angle moves posterosuperiorly

Posterior/downward tilt

• Rotational movement of scapula about frontal axis during glenohumeral hyperflexion

• Superior border moves posteroinferiorly & inferior angle moves anterosuperiorly

Shoulder girdle muscles

• Stabilize scapula so shoulder joint muscles will have a stable base to move the humerus

• Maintain scapula during shoulder joint actions

• Contract to move shoulder girdle & to enhance movement of upper extremity when shoulder goes through extreme ROM

• 5 muscles primarily involved in shoulder girdle movements

• All originate on axial skeleton & insert on scapula and/or clavicle

• Do not attach to humerus & do not cause shoulder joint actions

• Essential in providing dynamic stability of the scapula

Shoulder Girdle Muscles

1. Serratus Anterior

2. Pectoralis Minor

3. Trapezius

4. Rhomboid

5. Levator Scapulae

Serratus Anterior

• posterior and lateral

• abduction & upward rotation

Pectoralis Minor and (subclavius)

• anterior

• abduction, downward rotation, & depression

Subclavis: depression

Trapezius

• posterior

• Upper fibers: elevation, head extension

• Middle fibers: elevation, adduction, upper rotation

• Lower fibers: adduction, depression, upper rotation

Rhomboid

• posterior

• adduction, downward rotation, elevation

Levator Scapulae

• posterior

• elevation

Scapula Muscle Weakness and Posture

• Kyphosis: Forward shoulder due to scapula protractors & depressors becoming stronger & tighter

• Scapula winging: Relatively rare Serratus anterior weakness or paralysis is typically due to injury of the long thoracic nerve

Cervical Plexus

• Upper region

• Trapezius, Levator scapula, Rhomboid

• Branches of C3 & C4, C5, spinal accessory nerve

Brachial Plexus

• Lower region

• Levator scapula, Rhomboid, Serratus anterior, Pectoralis minor

• Branches of C5, C6, C7, C8, T1

Trapezius (Origin, Insertion, Movements)

• Origin: base of the skull, occipital protuberance, C7, T1-T12

• Insertion: clavicle, acromion process, scapula

• Movements:

~ Upper: scapula elevation, extension & rotation of the head

~ Middle: elevation, upward rotation & retraction of scapula

~ Lower: depression, retraction & upward rotation of scapula

Trapezius

Levator Scapulae (Origin, Insertion, Movements)

• Origin: C1-C4

• Insertion: scapula

• Movements: elevates the medial portion of the scapula, weak downward rotation, and adduction

Rhomboid Muscles: Major & Minor (Origin, Insertion, Movements)

• Origin: C7, T1, T2-T5

• Insertion: scapula

• Movements: adduction, downward rotation, elevation

Serratus Anterior (Origin, Insertion, Movements)

-Origin: ribs at the chest

• Insertion: medial scapula

• Movements: abduction and slight upward rotation

Serratus Anterior

Pectoralis Minor (Origin, Insertion, Movements)

• Origin: ribs

• Insertion: scapula

• Movements: abduction, downward rotation

Subclavius (Origin, Insertion, Movements)

• Origin: ribs

• Insertion: clavicle

• Movements: depression and abduction

Scapula Abduction (Examples, Agonists)

• Scapula move laterally away from spinous processes without rotation

• Ex: push-ups & bench press

• Agonists: Pectoralis Minor & Serratus Anterior

Scapula Adduction (Examples, Agonists)

• occurs with retractions

• Ex: bent-over rows

• Agonists: Middle Trapezius, Lower Trapezius, Rhomboids

Scapula Upward Rotation (Examples, Agonists)

• lateral & upward movement

• Ex: overhead press

• Agonists: Middle Trapezius, Lower Trapezius, Serratus anterior

Scapula Downward Rotation (Examples, Agonists)

• downward & medial movements

• Ex: chin-ups and dips

• Agonists: Pectoralis Minor and Rhomboid

Scapula Elevation (Examples, Agonists)

• lifting scapula without rotation in anatomic position

• Ex: Shoulder shrug

• Agonists: Levator scapula, Upper/middle trapezius, Rhomboid

Scapula Depression (Examples, Agonists)

• lowering the scapula

• Ex: Dips

• Agonists: Lower trapezius, Pectoralis minor

Muscles