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