Shoulder Articulations, Movements, Purpose, Etc..

scapula articulations

• Acromion with lateral clavicle (AC joint)

• Glenoid fossa with the head of the humerus (glenohumeral joint)

• Thoracic rib cage, ribs 2-7

scapula purpose

• Provide stability to support upper extremity movement

• Muscular attachment

• Transmit forces from upper extremity to axial skeleton

clavicle articulations

• Sternum and first costal cartilage (SC Joint)

• Acromion process (AC Joint)

clavicle purpose

• Holds arm away from trunk

• Transmits forces from upper extremity to axial skeleton

• Muscular attachment

humerus articulations

• Head with glenoid fossa (glenohumeral joint)

• Radius and ulna at distal end (elbow)

humerus purpose

• Primary mover of the shoulder joint

• Allows for reach

• Muscular attachment

sternoclavicular articulation

• Medial end of the clavicle

• manubriurm sterni

• first costal cartilage

sternoclavicular type

Synovial (plane)

sternoclavicular capsule

• Surrounds joint

• Lined by synovial membrane

sternoclavicular ligaments

• Sternoclavicular

• Costoclavicular

Supraclavicular nerve

• Nerve to subclavius muscle

sternoclavicular innervated by..

• Trapezius

• sternocleidomastoid

• levator scapulae

• rhomboid

action: elevates the scapula/clavicle

Pectoralis minor and subclavius

action: depresses the scapula/clavicle

serrtaus anterior

action: clavicle glides forward

(protracts; anterior)

trapezius and rhomboid

action: clavicle glides back

(retract; posterior)

acromioclavicular joint articulation (AC)

Between acromion and lateral end of Clavicle

AC joint type

Synovial (plane)

AC joint capsule

• Surrounds joint

• Lined by synovial membrane

AC joint ligaments

• Superior and inferior acromioclavicular

• Coracoclavicular

suprascapular nerve

acromioclavicular joint innervated by..

AC joint movement

Gliding movement

• Triggered by scapular rotation or clavicular elevation/depression

glenohumeral joint articulation

Head of humerus and glenoid fossa

• Hyaline articular cartilage

• Fossa is deepened by the labrum

glenohumeral joint type

Synovial ball and socket

glenohumeral joint capsule

• Medial attachment - margin of glenoid fossa

• Lateral attachment - anatomical neck of the humeral head to the medial side of humeral shaft

glenohumeral ligaments

• Transverse humeral ligament

• Coracohumeral ligament

• Coracoacromial ligament

glenohumeral joint synovial membrane

• Lines capsule

• Surrounds biceps tendon

• Forms a tubular sheath around the long head of biceps brachii

• Forms the subscapularis bursa

Axillary nerve and suprascapular nerve

glenohumeral joint is innervated by..

anterior fibers of the deltoid,

pectoralis major,

biceps, and

coracobrachialis

action: flexes shoulder/arm

posterior fibers of deltoid,

latssimus dorsi,

and teres major

action: extension of shoulder/arm

middle fibers of deltoid and supraspinatus

action: abduction of the shoulder/arm

pectoralis major,

latssimus dorsi,

teres major,

and teres minor

action: adduction of the shoulder/arm

infraspinatus,

teres minor,

and posterior fibers of deltoid

action: laterally rotates arm/shoulder

subscapularis,

latssimus dorsi,

teres major,

anterior fibers of deltoid,

pectoralis major

action: medially rotates arm/shoulder

trapezius origin

• from medial third of superior nuchal line of occipital bone

• external occipital protuberance

• ligamentum nuchae; from spine of seventh cervical vertebra

• spines and supraspinous ligaments of all thoracic vertebrae

trapezius insertion

• upper fibers - lateral third of clavicle

• middle fibers - acromion and upper border of spine of scapula

• lowest fibers - medial end of spine of scapula

trapezius nerve supply

• motor fibers from spinal part of accessory nerve (i.e. cranial nerve XI)

• sensory fibers from third and 4th cervical nerves

trapezius action

• upper fibers elevate scapula

• middle fibers pull scapula medially

• lower fibers pull medial border of scapula inferiorly resulting in glenoid cavity facing in anterosuperior directon

latissimus dorsi origin

• from posterior part of iliac crest

• lumbar fascia

• spines of lower six thoracic vertebrae (deep to trapezium); from lower three or four ribs

• few fibers from inferior angle of scapula

lattismus dorsi insertion

tendon wraps around lower border of teres major muscle and inserted into floor of bicipital groove of humerus

thoracodorsal nerve

(a branch of posterior cord of brachial plexus)

latissimus dorsi is innervated by..

latissimus dorsi action

extends, adducts, and medially rotates arm

levator scapulae origin

Transverse process of upper four cervical vertebrae

levator scapulae insertion

Medial border of scapula (opposite of supraspinous fossa)

3rd & 4th cervical nerve,

dorsal scapular nerve

levator scapulae innervated by..

levator scapulae action

Pulls scapula medially and superiorily

• Acts with middle fibers of traps and rhomboids

• Braces shoulder joint during flexion

rhomboid minor origin

Lower part of ligamentum nuchae and spine of 7th cervical and first thoracic vertebrae

rhomboid minor insertion

medial border of scapula

dorsal scapular nerve

rhomboid minor is innervated by..

rhomboid minor action

• Elevates medial border of scapula

• Pulls scapula medially