Ch 10 Muscle Identification and Mechanics

Comprehensive practice flashcards covering fascicle arrangements and musculoskeletal lever systems from the Muscle Mechanics lecture.

What are the four functional groups of skeletal muscles and what are their primary roles?

1. Prime movers (agonists) - primarily responsible for producing a movement.

   - Example: Biceps during elbow flexion.

2. Antagonists - oppose or reverse the action of the agonists.

   - Example: Triceps during elbow flexion

3. Synergists - assist the prime movers in performing a movement.

   - Example: Brachialis assisting the biceps

4. Fixators - hold a body part steady so another movement can occur efficiently.

   - Example: Core muscles stabilizing the spine during a lift

• Agonist = Moves

• Antagonist = Opposes

• Synergist = Assists

• Stabilizer = Holds steady

What are the seven criteria used to name skeletal muscles?

1. Location – Where the muscle is found.

• Example: Temporalis (located near the temporal bone).

2. Shape – The shape of the muscle.

• Example: Deltoid (triangular-shaped).

3. Relative Size – The size of the muscle compared to others.

• Example: Gluteus maximus (largest gluteal muscle).

4. Direction of Muscle Fibers – The direction the fibers run.

• Example: Rectus abdominis (straight fibers).

5. Number of Origins – How many attachment points or heads the muscle has.

• Example: Biceps brachii (two heads); triceps brachii (three heads).

6. Location of Attachments – The bones or structures the muscle attaches to.

• Example: Sternocleidomastoid (attaches to the sternum, clavicle, and mastoid process).

7. Action – The movement the muscle produces.

• Example: Flexor carpi radialis (flexes and abducts the wrist).

How many muscles are in the human body?

There are over 600 skeletal muscles in the human body

Which muscles form the quadriceps and the hamstrings?

The quadriceps consist of 4 muscles:

1. Rectus femoris

2. Vastus lateralis – outer thigh

3. Vastus medialis – inner thigh

4. Vastus intermedius – underneath the rectus femoris

The hamstrings consist of 3 muscles:

1. Biceps femoris – outer back thigh

2. Semitendinosus – inner back thigh

3. Semimembranosus – inner back thigh

Quads extend (straighten) the knee, while hamstrings flex (bend) the knee.

How are fascicles arranged in a circular muscle pattern, and what is a specific example?

Fascicles are arranged in concentric rings; an example is the orbicularis oris.

What characterizes a convergent fascicle arrangement, and which muscle serves as an example?

Fascicles converge toward a single tendon insertion; an example is the pectoralis major.

What is a parallel muscle fascicle arrangement, and what is an example?

Fascicles run parallel to the long axis of a straplike muscle; an example is the sartorius.

What describes a fusiform muscle arrangement, and which muscle is an example?

Spindle-shaped muscles with parallel fibers; an example is the biceps brachii.

How are fascicles arranged in a pennate muscle, and what is a primary example?

Short fascicles attach obliquely to a central tendon running the length of the muscle; an example is the rectus femoris.

What are the three specific types of pennate muscles identified in the lecture and their corresponding muscle examples?

Unipennate (extensor digitorum longus), bipennate (rectus femoris), and multipennate (deltoid).

What anatomical structure functions as the lever in the body's lever systems?

A bone (a rigid bar that moves on a fixed point or fulcrum).

What anatomical structure serves as the fulcrum in bodily lever systems?

A joint (the fixed point on which the lever moves).

How is effort defined within a musculoskeletal lever system?

The force supplied by muscle contraction applied to a lever to move a resistance (load).

What comprises the load in a biological lever system?

The resistance moved by the effort, which includes bone, tissues, and any added weight.

What is the structural arrangement of elements in a first-class lever system?

The fulcrum is located between the load and the effort (load-fulcrum-effort).

What class of lever system is illustrated in this diagram of the head and neck, and what anatomical structures serve as the fulcrum, effort, and load?

A first-class lever system. The atlanto-occipital joint is the fulcrum, the posterior neck muscles provide the effort, and the facial skeleton is the load being lifted.

How are the elements arranged in a first-class lever system?

The elements are arranged with the fulcrum positioned between the load and the effort, creating a load-fulcrum-effort structure.

What is the relative arrangement of components in a second-class lever system?

The load is located between the fulcrum and the effort (fulcrum-load-effort).

What class of lever system is represented when standing on tip-toe, and how are its anatomical components configured?

A second-class lever system. The joints of the ball of the foot act as the fulcrum, the calf muscles pulling upward on the heel exert the effort, and the weight of the body acts as the load.

How are the elements arranged in a third-class lever system?

The effort is applied between the fulcrum and the load (load-effort-fulcrum).

What class of lever system is depicted during forearm flexion, and what anatomical structures correspond to the fulcrum, effort, and load?

A third-class lever system. The elbow joint is the fulcrum, the effort is exerted on the proximal radius of the forearm by the biceps brachii muscle, and the load is the hand and distal end of the forearm.