Nine muscles insert on and move the humerus.
First, the pectoralis major originates on the medial half of the clavicle, one side of the sternum, on the costal cartilage (1-7) and the aponeurosis of the external oblique. It inserts on lateral lip of the intertubercular groove of the humerus. The pectorals major flexes, medially rotates and adducts the humerus.
Second, the deltoid originates from the lateral half part of the clavicle (anterior fibers), the acromion of the scapula (lateral fibers) and the spine of the scapula (posterior fibers). All the fibers merge on the deltoid tuberosity of the humerus.The anterior fibers flex and rotate the humerus medially. The lateral fibers abduct the humerus. The posterior fibers extend and laterally …show more content…
It functions to flex and medially rotate the humerus.
Fifth, the teres major originates on the lower lateral border and inferior angle of scapula and inserts on the medial lip of the intertubercular groove of the anterior humerus. It extends, medially rotates and adducts the humerus. It also represents a synergist of the latissimus dorsi.
The last four muscles make up the musculotendinous cuff. First, the supraspinatus muscle originates on the supraspinous fossa of scapula to insert on the superior part of the greater tubercle of humerus. It stabilizes and initiates abduction of the shoulder joint.
Next is the infraspinatus fossa which originates on the infraspinatus fossa of scapula to insert on the posterior facets of the greater tubercle of humerus. It laterally rotates the humerus. Then, the teres minor originates from the lateral border of dorsal scapular surface and inserts on the inferior facets of greater tubercle. It laterally rotates the humerus. Finally, the subscapularis originates from the subscapular fossa of the scapula and inserts on the lesser tubercle of the humerus. The teres minor represents the chief medial rotator of
First, the pectoralis major originates on the medial half of the clavicle, one side of the sternum, on the costal cartilage (1-7) and the aponeurosis of the external oblique. It inserts on lateral lip of the intertubercular groove of the humerus. The pectorals major flexes, medially rotates and adducts the humerus.
Second, the deltoid originates from the lateral half part of the clavicle (anterior fibers), the acromion of the scapula (lateral fibers) and the spine of the scapula (posterior fibers). All the fibers merge on the deltoid tuberosity of the humerus.The anterior fibers flex and rotate the humerus medially. The lateral fibers abduct the humerus. The posterior fibers extend and laterally …show more content…
It functions to flex and medially rotate the humerus.
Fifth, the teres major originates on the lower lateral border and inferior angle of scapula and inserts on the medial lip of the intertubercular groove of the anterior humerus. It extends, medially rotates and adducts the humerus. It also represents a synergist of the latissimus dorsi.
The last four muscles make up the musculotendinous cuff. First, the supraspinatus muscle originates on the supraspinous fossa of scapula to insert on the superior part of the greater tubercle of humerus. It stabilizes and initiates abduction of the shoulder joint.
Next is the infraspinatus fossa which originates on the infraspinatus fossa of scapula to insert on the posterior facets of the greater tubercle of humerus. It laterally rotates the humerus. Then, the teres minor originates from the lateral border of dorsal scapular surface and inserts on the inferior facets of greater tubercle. It laterally rotates the humerus. Finally, the subscapularis originates from the subscapular fossa of the scapula and inserts on the lesser tubercle of the humerus. The teres minor represents the chief medial rotator of