Arm muscles and Rotator cuff Flashcards
What is adduction?
Movement towards midline
add to the midline
What is abduction?
Movement away from midline
think abduct… or take away
Where is the deltoid?
From lateral ⅓ of clavicle, around the acromion and spine of the scapula and then all fibers insert on the deltoid tuberosity of the humerus
What do the anterior fibers of the deltoid do?
Flex and medially rotate the arm
What do the lateral fibers of the deltoid do?
Abduct the arm (away from midline)
What do the posterior fibers of the deltoid do?
Extend and laterally rotate arm
Where is the pectoralis major?
Medial ½ of clavicle and all of sternum to the humerus
What does the pectoralis major do?
Flex, adduct, and medially rotate humerus
What muscles form the axilla?
Anterior boder: pectoralis major
Posterior border: latissimus dorsi
Where is the latissimus dorsi?
Vertebrae and iliac crest to humerus
What does the latissimus dorsi do?
Extend, adduct, and medially rotate humerus
What shape is the teres minor?
Round
What does the teres major do?
Same as the latissimus dorsi.
Extend, adduct, and medially rotate humerus
What is the “little lat”?
Teres major- does what the latissimus dorsi does, but is smaller
Where is coracobrachialis?
Coracoid process to medial aspect on the shaft of the humerus
What does the coracobrachialis do?
Flex and adduct the humerus
Which muscles flex the humerus?
Deltoid, pectoralis major, coracobrachialis
Which muscles extend the humerus?
Deltoid, latissimus dorsi, teres major
What is the mnemonics for the rotator cuff muscles?
SITS- supraspinatus, infraspinatus, teres minor, subscapularis
What do the muscles of the rotator cuff do?
Tendons of these 4 muscles merge to help hold the head of the humerus in the glenoid fossa, because the glenoid is a shallow depression.
How can the rotator cuff be damaged?
Which muscle is most prone to injury?
Strenuous circumduction or hard blows to the shoulder, especially the supraspinatus
What does the supraspinatus do?
Abduct the humerus
What is a synergist of the supraspinatus?
Deltoid
What does the infraspinatus do?
Extend and laterally rotate the humerus
What movements does the teres minor do?
Extend, adduct, and laterally rotate humerus
Which SITS muscle keeps the head of the humerus in the rotator cuff?
Teres minor
What does the subscapularis do?
Medial rotation of humerus
