Which type of lever produces the most force?
The second class lever produces the most force.
Give an example of a muscle named for each of the following characteristics: direction of fibers, shape, action, size, origin and insertion, location, and number of tendons of origin.
For muscles named after their various characteristircs, ehre are possible correct responses: direction of fibers: external oblique; shape: deltoid; action: extensor digitorum; size: gluteus maximus; origin and insertion: sternocleidomastoid; location: tibialis anterior; number of tendons of origin: biceps brachii.
Critical Thinking: Minor-leagur pitcher Jose has been throwing a hundred pitches a day in order to perfect his curve ball. Lately he has experienced pain in his itching arm. The doctor diagnosed a torn rotator cuff. Jose was confused because he thought cuffs were only found in shirt sleeves, not inside his shoulder. Explain to Jose what the doctor means and how this injury could affect his arm movement.
The rotator cuff is formed by a combination of the tendons of four deep muscles of the shoulder—subscapularis, supraspinatus, infraspinatus, and teres minor. These muscles add strength and stability to the shoulder joint.
Although any of the muscles’ tendons can be injured, the subscapularis is most often damaged. Dependent upon the injured muscle, Jose may have trouble medially rotating his arm (subscapularis), abducting his arm
(supraspinatus), laterally rotating his arm (infraspinatus, teres minor), or extending his arm (teres minor).