Shoulder: Action, Origin, Insertion, & Nerve Innervation Flashcards
Trapezius
Action:
bilaterally: extend the head and neck.
unilaterally: laterally flex the head and neck to the same side, rotate the head and neck to the opposite side, elevate the scapula, and upwardly rotate the scapula.
middle fibers: adduct and stabilize the scapula.
lower fibers: depress and upwardly rotate the scapula.
Origin: external occipital protuberance, medial portion of superior nuchal line of the occiput, ligamentum nuchae, and spinous processes of C-7 through T-12.
Insertion: lateral one-third of clavicle, acromion, nd spine of the scapula.
Nerve Innervation: spinal portion of cranial nerve XI (accessory) and ventral ramus C2 to C4.
Deltoid
Action:
all fibers: abduct the shoulder.
anterior fibers: flex, internally (medially) rotate, and horizontally adduct the shoulder.
posterior fibers: extend, externally (laterally) rotate, and horizontally abduct the shoulder.
Origin: lateral one-third of clavicle, acromion, and spine of scapula.
Insertion: deltoid tuberosity.
Nerve Innervation: axillary C5 and C6.
Latissimus Dorsi
Action: extend, adduct, and internally (medially) rotate the shoulder.
Origin: inferior angle of the scapula, spinous processes of last six thoracic vertebrae, last three or four ribs, thoracolumbar fascia, and posterior iliac crest.
Insertion: intertubercular groove of humerus.
Nerve Innervation: thoracodorsal C6 to C8.
Teres Major
Action: extend, adduct, and internally (medially) rotate the shoulder.
Origin: inferior angle and lower one-third of lateral border of the scapula.
Insertion: crest of the lesser tubercle of the humerus.
Nerve Innervation: lower subscapular C5 to C7.
Rotator Cuff: Supraspinatus
Action: abduct the shoulder and stabilize the head of the humerus in the glenoid cavity.
Origin: supraspinous fossa of the scapula.
Insertion: greater tubercle of humerus.
Nerve Innervation:
Rotator Cuff: Infraspinatus
Action: externally (laterally) rotate and adduct the shoulder, and stabilize the head of the humerus in the glenoid cavity.
Origin: infraspinous fossa of the scapula.
Insertion: greater tubercle of the humerus.
Nerve Innervation: suprascapular C4 to C6.
Rotator Cuff: Teres Minor
Action: externally (laterally) rotate and adduct the shoulder, and stabilize the head of the humerus in the glenoid cavity.
Origin: upper two-thirds of the lateral border of the scapula.
Insertion: greater tubercle of the humerus.
Nerve Innervation: axillary C5 and C6.
Rotator Cuff: Subscapularis
Action: internally (medially) rotate the shoulder and stabilize the head of the humerus in the glenoid cavity.
Origin: subscapular fossa of the scapula.
Insertion: lesser tubercle of the humerus.
Nerve Innervation: upper and lower subscapular C5 to C7.
Rhomboid Major
Action: adduct, elevate, and downwardly rotate the scapula.
Origin: spinous processes of T2 to T5.
Insertion: medial border of the scapula between the spine of the scapula and inferior angle.
Nerve Innervation: dorsal scapular C4 and C5.
Rhomboid Minor
Action: adduct, elevate, and downwardly rotate the scapula.
Origin: spinous processes of C7 and T1.
Insertion: upper portion of medial border of the scapula, across from the spine of the scapula.
Nerve Innervation: dorsal scapular C4 and C5.
Levator Scapulae
Action:
unilaterally: elevate and downwardly rotate the scapula, laterally flex the head and neck, and rotate the head and neck to the name side.
bilaterally: extend the head and neck.
Origin: transverse processes of first through fourth cervical vertebrae
Insertion: medial border of scapula between the superior angle and superior portion of spine of scapula.
Nerve Innervation: cervical C3 and C4, and dorsal scapular C4 and C5.
Serratus Anterior
Action: abduct, upwardly rotate, and depress the scapula, and hold the medial border of the scapula against the rib cage.
Origin: external surfaces of upper eight or nine ribs.
Insertion: anterior surface of medial border of the scapula.
Nerve Innervation: long thoracic C5 to C8.
Pectoralis Major
Action:
all fibers: adduct and internally (medially) rotate the shoulder, assist to elevate the thorax during forced inhalation.
clavicular fibers: flex and horizontally adduct the shoulder.
sternocostal fibers: extend the shoulder.
Origin: medial half of clavicle, sternum, and cartilage of first through sixth ribs.
Insertion: crest of greater tubercle of humerus.
Nerve Innervation:
clavicular fibers: lateral pectoral C5 to C7.
sternocostal fibers: lateral and medial pectoral C6 and C8, T1
Pectoralis Minor
Action: depress, abduct, and downwardly rotate the scapula.
with the scapula fixed: assist to elevate the thorax during forced inhalation.
Origin: third, fourth, and fifth ribs.
Insertion: medial surface of coracoid process of the scapula.
Nerve Innervation: medial pectoral, with fibers from a communicating branch of the lateral pectoral C6 to C8, T1.
