Chapter 10: The Muscular System

Question 1

Describe the varied functions of muscles.

Answer 1

• Movement- muscles enable us to move from place to place and to move individual body parts.
• Stability- muscles maintain posture and stabilize joints by maintaining tension on tendons and bones.
• Control of body openings and passages- it helps us chew, speak, and close and open our eyes.
• Heat production- muscles produce about 85% of the body’s heat.
• Glycemic control- regulates blood glucose concentration.

Question 2

Describe the connective tissue components of a muscle and their role in muscle fibers

Answer 2

• Endomysium- thin sleeve of loose connective tissue that surrounds each muscle fiber.
• Perimysium- thick connective tissue sheath that wraps muscle fibers together to create fascicles.
• Epimysium- fibrous sheath that surrounds entire muscle.
• Fascia- sheet of connective tissue that separates neighboring muscles from each other and from the subcutaneous tissue.

Question 3

Describe the various shapes of the skeletal muscles

Answer 3

• Fusiform- thick in the middle, tapered at the end, relatively strong
• Parallel- uniform width and parallel fascicles; produce less force
• Triangular (convergent)- fan-shaped, small but relatively strong because of the large number of fibers in the wide part.
• Pennate- feather-shaped, generates more force because they fit more muscle fibers.
• Circular (sphincters)- form rings around certain body openings. When they contract, they constrict the opening and tend to prevent the passage of material through it.

Question 4

What is intrinsic muscle?

Answer 4

entirely contained within a particular region, has both origin and insertion there.

Question 5

what is extrinsic muscle?

Answer 5

acts upon a designated region but its origin is elsewhere.

Question 6

describe the innervation of spinal nerves

Answer 6

originates from the spinal cord, emerge through the intervertebral foramina, innervate muscles below the neck.

Question 7

describe the innervation of cranial nerves

Answer 7

originates from the base of the brain, emerge through the skull foramina, and innervate muscles of the head and neck.