Chapter 10 Muscular System

Question 1

What is the function of a prime mover (agonist)?

Answer 1

The muscle mainly responsible for producing a specific movement.

Example: Biceps brachii during elbow flexion.

Question 2

What is the role of an antagonist in muscle movement?

Answer 2

The muscle that opposes the action of the prime mover, maintaining balance and control.

Example: Triceps brachii during elbow flexion.

Question 3

What is a synergist muscle?

Answer 3

Helps the prime mover by adding force or reducing unnecessary movements.

Example: Brachialis assisting the biceps in elbow flexion.

Question 4

How does a muscle’s position relative to a joint affect its action?

Answer 4

The location of a muscle around a joint determines the direction of movement it produces.

Question 5

What movement do muscles anterior to a joint typically cause?

Answer 5

Flexion.

Question 6

What movement do muscles posterior to a joint typically cause?

Answer 6

Extension.

Question 7

What movement is produced by a muscle that crosses on the lateral side of a joint?

Answer 7

Abduction.

Question 8

What movement is produced by a muscle that crosses on the medial side of a joint?

Answer 8

Adduction.

Question 9

What is the first criterion used in naming muscles?

Answer 9

Location – Where the muscle is in the body

Example: Tibialis anterior — located on the front (anterior) of the tibia.

Question 10

What is the second criterion used in naming muscles?

Answer 10

Size – Relative size of the muscle

Example: Gluteus maximus — the largest of the gluteal muscles.

Question 11

What is the third criterion used in naming muscles?

Answer 11

Shape – The muscle’s geometric form

Example: Deltoid — shaped like a triangle (Greek “delta”).

Question 12

What is the fourth criterion used in naming muscles?

Answer 12

Direction of Fibers – Orientation of muscle fibers

Example: Rectus abdominis — fibers run straight (rectus) vertically.

Question 13

What is the fifth criterion used in naming muscles?

Answer 13

Number of Origins – How many tendons attach the muscle

Example: Biceps brachii — has two origins (“bi” = two).

Question 14

What is the sixth criterion used in naming muscles?

Answer 14

Location of Origin and Insertion – Which bones the muscle is connected to

Example: Sternocleidomastoid — originates on the sternum and clavicle, inserts on the mastoid process.

Question 15

What is the seventh criterion used in naming muscles?

Answer 15

Action – The primary movement the muscle causes

Example: Flexor carpi radialis — flexes the wrist (carpus).

Question 16

What does the name ‘adductor brevis’ indicate about the muscle?

Answer 16

Adductor = performs adduction; Brevis = short muscle

Indicates that it pulls the limb toward the body and is short in length.

Question 17

What does the name ‘quadriceps femoris’ indicate about the muscle?

Answer 17

Quadriceps = four-headed muscle; Femoris = associated with the femur (thigh bone)

Indicates that it has four muscle heads and is related to the thigh.

Question 18

What does the name ‘tibialis anterior’ indicate about the muscle?

Answer 18

Tibialis = near the tibia; Anterior = located on the front side

Indicates its proximity to the tibia and its position at the front.

Question 19

What does the name ‘iliacus’ indicate about the muscle?

Answer 19

Iliacus = originates from or near the ilium (part of the pelvis)

Indicates its origin related to the ilium.

Question 20

What are the common patterns of muscle fascicle arrangement?

Answer 20

Parallel, Fusiform, Circular, Convergent, Unipennate, Bipennate, Multipennate

These patterns relate to the muscle’s function and power generation.

Question 21

Describe the Parallel fascicle arrangement.

Answer 21

Fascicles run alongside the muscle’s long axis, allows greater range of motion, generates less power due to fewer fibers. Example: Sartorius

Parallel muscles are typically long and thin.

Question 22

What is a Fusiform muscle?

Answer 22

Spindle-shaped, thick in the middle, tapered at ends, offers moderate range and power. Example: Biceps brachii

Fusiform muscles have a similar function to parallel muscles but can generate more power.

Question 23

How are Circular muscles arranged?

Answer 23

Fascicles arranged in concentric rings, controls openings, not built for power. Example: Orbicularis oris

Circular muscles are often found around openings like the mouth.

Question 24

What characterizes a Convergent muscle arrangement?

Answer 24

Broad origin narrowing to a single tendon, allows versatile movement, produces moderate power. Example: Pectoralis major

Convergent muscles can pull in different directions.

Question 25

What is the defining feature of Unipennate muscles?

Answer 25

Fascicles attach to one side of a tendon, generates high power. Example: Extensor digitorum ## Footnote Unipennate muscles are efficient in generating force due to their structure.

Question 26

Describe Bipennate muscles.

Answer 26

Fascicles attach on both sides of a central tendon, produces higher power. Example: Rectus femoris ## Footnote Bipennate muscles can generate more power than unipennate due to the increased number of fibers.

Question 27

What is a Multipennate muscle?

Answer 27

Multiple angled fascicle sections with several tendons, produces the highest power. Example: Deltoid ## Footnote Multipennate muscles have the most fibers packed into a given area, maximizing power output.

Question 28

Define lever.

Answer 28

A rigid bar (usually a bone) that moves on a fixed point called a fulcrum when force (effort) is applied to move a load.

Question 29

What is mechanical advantage in the context of a lever?

Answer 29

Occurs when the effort arm is longer than the load arm. ## Footnote Result: Less force needed to move the load. Focus: Power.

Question 30

What is mechanical disadvantage in the context of a lever?

Answer 30

Happens when the effort arm is shorter than the load arm. ## Footnote Result: More force needed—but allows faster, broader movement. Focus: Speed & range.

Question 31

Fill in the blank: A lever operating at a mechanical advantage requires _______ force to move the load.

Answer 31

less

Question 32

Fill in the blank: A lever operating at a mechanical disadvantage allows for _______ movement.

Answer 32

faster

Question 33

True or False: A lever that operates at a mechanical advantage focuses on speed and range.

Answer 33

False

Question 34

True or False: A lever that operates at a mechanical disadvantage requires more force to move the load.

Answer 34

True

Question 35

What are the three types of lever systems?

Answer 35

First-Class Lever, Second-Class Lever, Third-Class Lever ## Footnote Each type has a unique arrangement of effort, fulcrum, and load.

Question 36

What is the arrangement of a First-Class Lever?

Answer 36

Effort – Fulcrum – Load ## Footnote This lever can operate at a mechanical advantage or disadvantage depending on placement.

Question 37

What is an advantage of a First-Class Lever?

Answer 37

Can operate at a mechanical advantage or disadvantage ## Footnote Example: Neck muscles tilting the head back (atlanto-occipital joint).

Question 38

What is the arrangement of a Second-Class Lever?

Answer 38

Fulcrum – Load – Effort ## Footnote This lever always works at a mechanical advantage.

Question 39

What is an advantage of a Second-Class Lever?

Answer 39

Always works at a mechanical advantage (force-efficient) ## Footnote Example: Standing on tiptoe (calf muscles lifting the body).

Question 40

What is the arrangement of a Third-Class Lever?

Answer 40

Fulcrum – Effort – Load ## Footnote This lever works at a mechanical disadvantage.

Question 41

What is an advantage of a Third-Class Lever?

Answer 41

Enables speed and range but requires more force ## Footnote Example: Flexing forearm with biceps brachii.

Question 42

Which lever type is the fastest in muscle mechanics?

Answer 42

Third-Class Lever ## Footnote This lever type sacrifices force efficiency for speed and range of motion.

Question 43

How does a third-class lever function in terms of effort and load movement?

Answer 43

Effort is applied close to the fulcrum, making the end of the lever (load) move faster and farther. ## Footnote Example: Biceps brachii flexing the forearm.

Question 44

When prying an old fence post out of the ground, where should the fulcrum be positioned?

Answer 44

Closer to the post (the load). ## Footnote This creates a long effort arm, giving you mechanical advantage.

Question 45

What is the benefit of having the fulcrum closer to the load when using a lever?

Answer 45

It allows you to apply less force to move the heavy post more easily. ## Footnote This mimics a second-class lever system, which is power-efficient.