Chapter 11 The Muscular System (ch. review)

What is the difference between a muscle's origin and insertion?

The origin is the attachment to the stationary bone, while the insertion is the attachment to the movable bone.

In the context of skeletal movement, what do bones and joints represent?

Bones serve as levers, and joints serve as fulcrums.

What are the three classes of levers in the body?

First-class, second-class, and third-class levers.

What is the most common type of lever in the human body?

Third-class lever.

What two properties of a muscle are affected by its fascicular arrangement?

Power and range of motion.

What is the function of a synergist muscle?

To assist a prime mover by reducing unnecessary movement.

What is the role of a fixator muscle?

To stabilize the origin of a prime mover so it can act more efficiently.

What are the primary criteria used to name skeletal muscles?

Direction of fascicles, size, shape, action, number of origins, location, and sites of origin and insertion.

How do muscles of facial expression differ from other skeletal muscles?

They move the skin rather than a joint when they contract.

What is unique about the extraocular muscles?

They are among the fastest contracting and most precisely controlled skeletal muscles in the body.

What are the muscles that move the mandible at the temporomandibular joint called?

Muscles of mastication.

What is the function of the suprahyoid and infrahyoid muscles?

They assist in deglutition and speech, and help stabilize the hyoid bone.

Besides moving the vertebral column, what are the functions of the abdominal muscles?

Protecting abdominal viscera, compressing the abdomen, and assisting in defecation, urination, vomiting, and childbirth.

What is the primary function of the thoracic muscles used in breathing?

To alter the size of the thoracic cavity to allow for inhalation and exhalation.

What are the two main functions of the pelvic floor muscles?

Supporting pelvic viscera and functioning as sphincters.

What is the function of the muscles of the perineum?

Assisting in urination, erection, ejaculation, and defecation.

Why is it important for thoracic muscles to stabilize the scapula?

To provide a stable base of origin for muscles that move the humerus.

How are the muscles of the arm that move the radius and ulna organized?

Into flexor and extensor compartments.

What are extrinsic muscles of the hand?

Muscles located in the forearm that act on the digits.

What is the primary purpose of the intrinsic muscles of the hand?

To enable skilled activities and the grasping/manipulation of objects.

Why are the muscles of the gluteal region larger than those in the upper limb?

They must provide the power necessary for movement of the femur in the lower limb.

How are the muscles of the thigh categorized by compartment?

Medial (adductor), anterior (extensor), and posterior (flexor) compartments.

How are the muscles of the leg that move the foot and toes divided?

Into anterior, lateral, and posterior compartments.

What are the primary functions of the intrinsic muscles of the foot?

Support and locomotion.