A&P Ch 11

17. Name the three groups of muscles constituting the intrinsic muscles of the hand. Briefly describe their structures and functions.

1. Thenar: four muscles that act on the thumb and form the lateral rounded contour of the palm 2. Hypothenar: three muscles that act on the little finger and form the medial rounded contour of the palm 3. Intermediate: 12 muscles acting on all digits except the thumb; subgrouped as lumbricals, palmar interossei, and dorsal interossei, and located between metacarpals; needed for all phalangeal movements

3. This is an inflammation of the synovial membrane surrounding a joint. a. tenosynovitis b. tendonitis c. synovitis d. tendon inflammation e. capsule inflammation

A

5. Motion will occur in a muscle when the ______ supplied exceeds the _______. a. effort, load b. resistance, lever c. load, effort d. load, resistance e. lever, effort

A

9. This type of fascicle arrangement has the fascicles spread over a broad area and converges at a thick central tendon. a. triangular b. pennate c. circular d. fusiform e. multipennate

A

6. Briefly describe the differences between a mechanical advantage and a mechanical disadvantage.

A lever operates at a mechanical advantage when a smaller effort can move a heavier load. The effort must move a greater distance or have a longer range of motion and be faster than the load. A lever operates at a mechanical disadvantage when a harder effort moves a lighter load. The effort must move more slowly and for a shorter distance than the load.

1. Most muscles cross at least one a. tendon b. joint c. bone d. ligament e. body plane

B

10. What is another name for a prime mover? a. antagonist b. agonist c. synergist d. asynergist e. fixator

B

2. The attachment of a muscles tendon to the stationary bone is called the ______; the attachment of the muscles other tendon to the movable bone is called ______. a. origin, action b. insertion, action c. origin, insertion d. insertion, origin e. insertion, action

C

8. Which of the following is not a fascicle arrangement? a. pennate b. triangular c. oval d. parallel e. fusiform

C

11. This type of muscle works by stabilizing the origin of a prime mover so that it can act more efficiently. a. synergist b. agonist c. antagonist d. fixator e. secondary mover

D

4. A lever is acted on at two different points by two different forces which are a. fulcrum and resistance b. leverage and load c. lever and resistance d. effort and load e. lever and effort

D

13. Which of the following is not one of the descriptive ways to name a muscle? a. Size b. Shape c. Number of origins d. Sites of origins e. Number of cells

E

7. Briefly describe the three categories of levers, an example of each and if each one works at an advantage or disadvantage.

If the fulcrum is between the effort and the load it is a first class lever. Scissors are an example of a first class lever. A first class lever can produce either a mechanical advantage or disadvantage depending on whether the effort or load is closer to the fulcrum. If the load is between the fulcrum and the effort it is a second class lever. A wheel barrow is an example of a second class lever. They operate at a mechanical advantage because the load is always closer to the fulcrum than the effort. If the effort is between the fulcrum and the load it is a third class lever. Forceps are an example of a third class lever. They operate at a mechanical disadvantage because the effort is always closer to the fulcrum than the load.

12. Briefly describe four main benefits of stretching before exercising.

Stretching can increase flexibility and a flexible joint has the ability to move through a greater range of motion which improves performance. Stretching decreases resistance in various soft tissues so there is less of a chance of exceeding maximum tissue extensibility during activity. Stretching can reduce some of the muscle soreness that results after exercise. Stretching can help realign soft tissues to improve and maintain good posture.

14. Identify the anatomical parts corresponding to the generic components of a lever system. Describe the arrangement of these parts in first, second, and third class lever systems.

The bone is the lever; the joint is the fulcrum; the muscle contraction pulling on its insertion point is the effort; the weight of the part to be moved is the resistance. A first class lever has the fulcrum between the effort and the resistance; a second class lever has the resistance in the middle; the third class lever has the effort in the middle. In all cases, the lever moves around the fulcrum.

18. Name and describe the locations and actions of the muscles typically used in breathing.

The diaphragm forms the floor of the thoracic cavity. It flattens during inspiration to increase the size of the thoracic cavity. The external intercostals between the ribs increase the lateral and anteroposterior dimensions of the thorax. Internal intercostals between ribs pull ribs together in the opposite movement during expiration to decrease the size of the thoracic cavity. The diaphragm relaxes during expiration to form a dome and decrease the size of the thoracic cavity. The anterior scalenes and the pectoralis minor may assist during forced inspirations.

15. Discuss the roles of prime movers, antagonists, synergists, and fixators in movement.

The prime mover contracts to cause a particular action. The antagonist causes the opposite action, and so, must relax while the prime mover contracts. Synergists prevent unwanted movements during an action, while fixators stabilize the origin of the prime mover. Both allow the prime mover to work more efficiently.

16. Chuck has a rotator cuff injury. Which muscles and associated structures might be involved, and what sorts of activities might have led up to this injury. What movements might be inhibited by this injury?

The tendons of the subscapularis, supraspinatus, infraspinatus, and teres minor make up the rotator cuff. Any activity involving these muscles, from throwing baseballs to shoveling snow, could cause the problem. Inhibited movements depend on specific muscle involved: medial and lateral rotation, adduction, abduction, or extension of arm.