Shoulder Muscles Flashcards
Deltoid
O: Spine of the scapula, acromion, lateral 1/3 of clavicle
INS: Deltoid tuberosity of humerus
INN: Axillary nerve
ACT: Abducts arm; anterior fibers can flex arm, posterior fibers can extend arm
Supraspinatus
O: Supraspinous fossa
INS: Greater tubercle of humerus (superior part)
INN: Suprascapular nerve
A: Abducts arm (also responsible for initiating abduction)
Infraspinatus
O: Infraspinous fossa
INS: Greater tubercle of humerus (middle part)
INN: Suprascapular nerve
A: Laterally rotates arm
Teres minor
O: Lateral border of scapula (upper half)
INS: Greater tubercle of humerus (inferior part)
INN: Axillary nerve
A: Laterally rotates arm
Teres major
Lateral border of scapula (lower half and inferior angle)
Anterior side of humerus (medial lip of intertubercular groove)
Lower subscapular nerve
Extends, adducts and medially rotates arm
Subscapularis
O: Subscapular fossa
INS: Lesser tubercle of humerus
INN: Upper and Lower subscapular nerves
A: Adducts and medially rotates arm
Pectoralis major
O: Clavicular head: medial ½ of clavicle + Sternocostal head: sternum and adjacent costal cartilages
INS: Anterior side of humerus (lateral lip of intertubercular groove)
INN: Medial and Lateral pectoral nerves
A: Flexes, adducts and medially rotates arm
Pectoralis minor
O: Ribs 3-5
INS: Coracoid process of scapula
INN: Medial pectoral nerve
A: Depresses scapula and assists with protraction
Serratus anterior
O: Upper ribs (typically 1-8)
INN: Medial border of the scapula (anterior side)
INS: Long thoracic nerve
A: Protracts and laterally rotates scapula
