Ch 2 - Muscle Shape And Fiber Arrangement

Question 1

The larger the cross-section diameter, the ______ force a muscle exerts.

Answer 1

More

Question 2

The longer a muscle fiber/muscle, the more it can ________, therefore the more effective at moving joints.

Answer 2

Shorten

Question 3

What are the two types of fiber arrangements?

Answer 3

• parallel: arranged parallel to the length of the muscle, produces greater range of movement
• pennate: arranged obliquely to their tendons (like a feather), produces greater power/force

Question 4

Flat

Answer 4

• parallel arrangement
• thin and broad, originating from aponeuroses that allow the muscle to spread its forces over a broad area
• rectus abdominus, external oblique

Question 5

What would happen if the rectus abdominus went lax?

Answer 5

There would be more stress on your back, and your pelvis would tilt anteriorly

Question 6

Fusiform

Answer 6

• tapers to tendons on each end, focus their power on small bony targets
• very long, so can shorten a lot
• biceps brachii, brachialis

Question 7

Strap

Answer 7

• parallel
• very long parallel configuration, focus their power on smal boney targets
• sartorius

Question 8

Radiate

Answer 8

• parallel
• originate on broad aponeuroses and converge into a single point of attachment via a tendon
• pectoralis major, trapezius

Question 9

Sphincter

Answer 9

• parallel
• fibers concentrically arranged around a body opening, basically a circular strap muscle
• orbicularis oris, orbicularis oculi

Question 10

Unipennate

Answer 10

• pennate
• run obliquely from a tendon on one side only
• biceps femoris, extensor digitorum longus, tibialis posterior

Question 11

Bipennate

Answer 11

• pennate
• run obliquely from a central tendon on both sides
• strongest of pennate muscles
• rectus femoris, flexor hallucis longus

Question 12

What is the job of the flexor hallucis longus?

Answer 12

• bipennate muscle in the big toe that propels the entire body foward

Question 13

Multipennate

Answer 13

• pennate
• several tendons with fibers running diagonally btwn them
• least strong of the pennate muscles, but is the most versatile in how it produces movement
• deltoid

Question 14

The smaller the moment arm, the _______ the ROM, and vice versa.

Answer 14

Larger

Question 15

Irritability/excitability

Answer 15

• sensitive or responsive to chemical, electrical, or mechanical stimuli. Respond by developing tension
• if the stimulus isn’t receive or interpreted, the muscle doesn’t know what to do

Question 16

Contractility

Answer 16

Ability of muscle to contract and develop tension or internal force against resistance when stimulated

Question 17

Extensibility

Answer 17

The ability of muscle to be passively stretched beyond its normal resting length

Question 18

Elasticity

Answer 18

The ability of muscle to return to its original resting length following stretch

Question 19

The smaller the pennation angle, the ______ the force. And vice versa

Answer 19

Greater