A & P Ch 9 Muscular System 3/3

A lever has four basic components:

(1) a rigid bar or rod, (2) a fulcrum or pivot on which the bar turns, (3) an object moved against resistance, and (4) a force that supplies energy to move the bar.

Signs of aging in the muscular system begin to appear in one's ___, although a person can still be active. At a microscopic level, supplies of the molecules that enable muscles to function—_______, ATP, and creatine phosphate—_____. Gradually, the muscles become smaller, ____, and capable of less forceful contraction. Connective tissue and ____ cells begin to replace some muscle tissue.

40s; myoglobin; decline; drier; adipose

what is the size of the pectoralis major? where is it located?

A large (major) muscle in the pectoral region (chest).

According to the National Institute on ____, exercise should include strength training and _____.

Aging; aerobics

the flexors that move the arm are

Coracobrachialis and Pectoralis major

what is the shape of a deltoid?

Shaped like a delta or triangle.

the Rotators of the arm are

Subscapularis, Infraspinatus, and Teres minor

the Abductors of the arm are

Supraspinatus and Deltoid

the Extensors of the arm are

Teres major and Latissimus dorsi

An agonist causes an ____, and an ____ works against the action.

action; antagonist

In the example of elbow flexion, the biceps brachii is the ____ for flexion and the ____ brachii is the antagonist to that movement. Note that the role of a muscle is dependent on the ______, because in the opposite example of elbow extension, the triceps ____ is the agonist and the biceps brachii is the _____.

agonist; triceps; movement; brachii; antagonist

The names of muscles often describe them. A name may indicate a muscle's size, shape, location, action, number of _____, or the ____ of its fibers

attachments; direction

When the upper limb bends, the forearm bones represent the rigid ____, the elbow joint is the ____, the hand is moved _____ the resistance provided by the weight, and the force is supplied by muscles on the _____ side of the arm (Part 1/2)

bar; fulcrum; against; anterior

Some muscles have more than one origin or insertion. The biceps ____ in the arm, for example, has two origins. This is reflected in its name biceps, meaning "two ____." The head of a ____ is the part nearest its origin.

brachii; heads; muscle

one head of the biceps brachii is attached to the ____ process of the ____, and the other head arises from a ___ above the glenoid ___ of the scapula. The muscle runs along the anterior surface of the _____ and is inserted by a single ____ on the radial tuberosity of the radius.

coracoid; scapula; tubercle; cavity; humerus; tendon

Exercise can help maintain a healthy muscular system throughout life, countering the less effective oxygen ____ that results from the decreased muscle ____ that accompanies aging.

delivery; mass

By age ____, nearly half the muscle mass has atrophied, due to a decline in ____ neuron activity. Diminishing muscular strength slows____.

eighty; motor; reflexes

The parts of a third-class lever are in the sequence resistance-_____-fulcrum. Eyebrow tweezers or forceps used to ____ an object illustrate this type of lever.

force; grasp

one end of a skeletal muscle typically attaches to a relatively _____ or fixed part on one side of a joint, and the other end attaches to a ____ part on the other side of that joint, such that the muscle ____ the joint

immovable; movable; crosses

Whenever limbs or other body parts move, bones and muscles ____ as simple mechanical devices called _____

interact; levers

Exercise can even lead to formation of ____ muscle by stimulating skeletal muscle cells to release interleukin-6 (___-_), a type of proinflammatory molecule called a ___. The IL-6 stimulates satellite cells, which function as muscle ___ cells. They divide and migrate, becoming ____ into the muscle fiber.

new; IL-6; cytokine; stem; incorporated

The less movable end is called the ____ of the muscle, and the more movable end is called its ____. When a muscle contracts, its insertion is pulled ____ its origin

origin; insertion; toward

The term agonist is often used interchangeably with ____ ______, but in many applications the term prime mover refers to an agonist that provides most of the ____ for a movement when more than one ____ contributes to that movement.

prime mover; force; muscle

One of these muscles, the biceps brachii, is attached by a tendon to a _____ (radial tuberosity) on the ____ bone in the forearm, a short distance ____ the elbow. Because the parts of this lever are arranged in the sequence resistance-force-fulcrum, it is a ___-class lever. (Part 2/2)

projection; radius; below; third

Levers provide a range of movements. Levers that move limbs, for example, produce ___ motions, whereas others, such as those that move the head, help maintain ____ with minimal effort.

rapid; posture

The human body also has a second-class lever (fulcrum-____-force). The fulcrum is the _____ joint. Muscles supply the resistance, attaching to a projection (coronoid process) and body of the ____. These muscles resist or oppose ____ the mouth. The muscles attached to the ____ area of the mandible provide the force that opens the mouth.

resistance; temporomandibular; mandible; opening; chin

The parts of a second-class lever are in the sequence fulcrum-_____-force, as in a ______.

resistance; wheelbarrow

A first-class lever's parts are like those of a pair of _____. Its fulcrum is located _____ the resistance and the force, making the sequence of components resistance-______-force. Other examples of first-class levers are seesaws and hemostats (devices used to ___ blood vessels).

scissors; between; fulcrum; clamp

In most cases other muscles, called _____, contribute to an action by helping the agonist. Again, however, the relationship between muscles depends on the _____. For example, pectoralis major, a ____ muscle, and ___ dorsi, a back muscle, are synergistic for medial rotation of the _____. However, they are antagonistic for ____ and extension of the shoulder.

synergists; action; chest; latissimus; arm; flexion

When the biceps brachii contracts, its insertion is pulled _____ its origin, and the elbow flexes.

toward