Shoulder Complex (2B) Flashcards
Attachments of pectoralis major
- proximal = medial clavicle (clavicular head), sternum, upper ribs (sternal head)
- distal = anterior/medial humerus
Innervation of pectoralis major
Lateral and medial pectoral nerves
Actions of pectoralis major
All fibers
- adduct the shoulder
- internally (medially) rotate the shoulder
- assist to elevate the thorax during forced inhalation (with the arm fixed)
Clavicular fibers
- flex the shoulder
- horizontally adduct the shoulder
Sternocostal fibers
- extend the shoulder
Attachments of pectoralis minor
- proximal = 3-5th ribs (middle ribs)
- distal = coracoid process
- can move either attachment
Innervation of pectoralis minor
Medial pectoral nerve
Actions of pectoralis minor
- depression the scapula
- abduction the scapula
- downwardly rotate the scapula
- assist to elevate the thorax during force inhalation (with the scapula fixed)
Attachments of coracobrachialis
- proximal = coracoid process
- distal = anterior/medial humerus
Innervation of coracobrachialis
Musculocutaneous nerve
Actions of coracobrachialis
- flex the shoulder
- adduct the shoulder
Attachments of deltoid
- proximal = lateral clavicle, acromion, lateral spine of the scapula
- distal = lateral humerus
Innervation of deltoid
Axillary nerve
Actions of deltoid
All fibers
- abduct the shoulder
Anterior fibers
- flex the shoulder
- internally (medially) rotate the shoulder
- horizontally adduct the shoulder
Posterior fibers
- extend the shoulder
- externally (laterally) rotate the shoulder
- horizontally abduct the shoulder
Muscles of rotator cuff
- SITS
- supraspinatus
- infraspinatus
- teres minor
- subscapularus
Attachments of supraspinatus
- proximal = supraspinous fossa
- distal = lateral humerus
Innervation of supraspinatus
Suprascapular nerve
Actions of supraspinatus
- abduct the shoulder
- stabilize the head of humerus in glenoid cavity
Attachments of infraspinatus
- proximal = infraspinous fossa
- distal = posterior/lateral humerus
Innervation of infraspinatus
Suprascapular nerve
Actions of infraspinatus
- externally (laterally) rotate the shoulder
- adduct the shoulder
- stabilize the head of humerus in glenoid cavity
Attachments of teres minor
- proximal = lateral border of scapula
- distal = posterior/lateral humerus
Innervation of teres minor
Axillary nerve
Actions of teres minor
- externally (laterally) rotate the shoulder
- adduct the shoulder
- stabilize the head of humerus in glenoid cavity
Attachments of subscapularis
- proximal = subscapular fossa
- distal = anterior/lateral humerus
Innervation of subscapularis
Upper and lower subscapular nerve
Actions of subscapularis
- internally (medially) rotate the shoulder
- stabilize the head of humerus in glenoid cavity
Attachments of teres major
- proximal = lower 1/3 of lateral border of scapula
- distal = anterior/medial humerus
Innervation of teres major
Lower subscapular nerve
Actions of teres major
- extend the shoulder
- adduct the shoulder
- internally (medially) rotate the shoulder
Attachments of latissimus dorsi
- proximal = inferior angle of scapula, spinous processes of inferior T-spine, and thoracolumbar fascia/posterior iliac crest
- distal = anterior/medial humerus
Innervation of latissimus dorsi
Thoracodorsal nerve
Actions of latissimus dorsi
- extend the shoulder
- adduct the shoulder
- internally (medially) rotate the shoulder
Attachments of trapezius
- proximal = occiput of scull, ligamentum nuchae, and C7-T12 spinous processes
- distal = lateral 1/3 clavicle, spine of scapula, and acromion
Innervation of trapezius
Cranial nerve (XI - Accessory)
Actions of trapezius
Upper fibers
- extend the head and neck
Upper fibers (unilaterally)
- laterally flex the head and neck to the same side
- rotate the head and neck to the opposite side
- elevate the scapula
- upwardly rotate the scapula
Middle fibers
- adduct scapula
- stabilize scapula
Lower fibers
- depression scapula
- upwardly rotate the scapula
Attachments of levator scapula
- proximal = transverse processes of C1-4
- distal = medial border of scapula
Innervation of levator scapula
Dorsal scapular nerve
Actions of levator scapula
Unilaterally
- elevate the scapula
- downwardly rotate the scapula
- laterally flex the head and the neck
- rotate the head and neck to the same side
Bilaterally
- extend the head and neck
Attachments of rhomboid major and minor
- proximal = spinous processes of C7-T5
- distal = medial border of scapula
Innervation of rhomboid major and minor
Dorsal scapular nerve
Actions of rhomboid major and minor
- adduct the scapula
- elevate the scapula
- downwardly rotate the scapula
Attachments of serratus anterior
- proximal = upper ribs
- distal = medial border of scapula
Innervation of serratus anterior
Long thoracic nerve
Actions of serratus anterior
With the origin fixed
- abduct the scapula
- upwardly rotate the scapula
- depression the scapula
- hold the medial border of the scapula against the rib cage
With the scapula fixed
- may act to elevate the thorax during forced inhalation
