ch:10Muscle system notes

What are the three types of muscle tissue in the body?

Skeletal, cardiac, and smooth muscle

What is the main function shared by all muscle types?

Converting chemical energy (ATP) into mechanical energy (movement)

. About how many skeletal muscles are in the human body?

Around 600–650.

What is myology?

The study of muscles

What does the word "muscle" literally mean?

“Little mouse,” because ancient Greeks thought muscles looked like mice moving under the skin

What are the six major functions of muscles?

Movement, stability, control of body openings, heat production, hormone secretion, and glycemic control.

How do muscles help regulate body temperature?

They generate 20–30% of body heat at rest and up to 85% during exercise.

Why do muscles play a role in glycemic control?

Because skeletal muscles absorb, store, and use a lot of the body’s glucose, helping stabilize blood sugar.

why do muscles play a role in hormone secretion like?

- During exercise muscles release hormones that stimulate the liver to convert glycogen to glucose and to break down fats for energy.

What prefix means muscle?

Myo-

What prefix means flesh or meat?

Sarco-

What is the muscle cell's plasma membrane called?

Sarcolemma

What is the muscle cell's endoplasmic reticulum called?

Sarcoplasmic reticulum

Name the four tissues found in skeletal muscle.

Muscular tissue, connective tissue, nerves, and blood vessels.

What are the three layers of connective tissue in muscle (from deepest to most superficial)?

➡️ Endomysium → Perimysium → Epimysium

What does the endomysium surround?

Each individual muscle fiber.

What does the perimysium surround?

A fascicle (a bundle of muscle fibers).

What does the epimysium surround?

The entire muscle

What is fascia?

A sheet of connective tissue separating muscles or muscle groups.

What ions are important for muscle contraction?

Calcium (Ca²⁺), Sodium (Na⁺), and Potassium (K⁺). within the endomysium

How does fascicle orientation affect muscle strength and motion?

It determines the direction of pull and strength of the muscle.

Describe fusiform muscles. Give examples.

Thick in the middle, tapered ends (e.g., biceps brachii, gastrocnemius).

Describe parallel muscles. Give examples.

Uniform width, parallel fascicles (e.g., rectus abdominis).

Describe triangular (convergent) muscles. Give examples.

Fan-shaped, broad at one end, narrow at the other (e.g., pectoralis major, temporalis).

Describe pennate muscles and their types.

➡️ Feather-shaped muscles:

Unipennate: fascicles approach tendon on one side (extensor digitorum)

Bipennate: fascicles approach tendon on both sides (rectus femoris)

Multipennate: several feathers converge at a point (deltoid)

Describe circular (sphincter) muscles and their function.

Form rings around openings and control passage (e.g., orbicularis oris).

Which fascicle arrangement produces the most force?

Pennate, because it can pack more fibers in a given space.

What is the origin of a muscle?

The fixed or stationary attachment point.

What is the insertion of a muscle?

The moveable attachment point.

What is a direct muscle attachment?

Muscle fibers attach directly to bone (e.g., temporalis, deltoid, pectoralis major).

What is an indirect muscle attachment?

Muscle attaches to bone via fibrous cord called tendon (e.g., biceps brachii, rectus femoris).

-more range of motion/ more pron to injury

What are the four functional categories of muscle actions?

Prime mover (agonist), synergist, antagonist, fixator.

What is a prime mover (agonist)?

Muscle that produces the main force for a movement

- Brachialis is prime mover when flexing elbow, the biceps brachii is prime mover when supinating the forearm

What is a synergist?

A muscle that assists the prime mover.

-brachialis assists biceps brachii

What is an antagonist?

A muscle that opposes the prime mover's action.

Example: triceps brachii extends elbow

Antagonist plays two important roles in muscle function

1) maintain body or limb position

2) they control rapid movement like shadow boxing

What is a fixator?

A muscle that stabilizes a bone to prevent unwanted movement.

Give an example of each type: if I flex my elbow➡️

Prime mover: brachialis (flexing elbow)

Synergist: biceps brachii and brachioradialis

Antagonist: triceps brachii

what does innervation mean?

The identity of the nerve that stimulates a muscle

Why is knowing a muscles innervation important

It helps diagnose nerve spinal cord or brainstem injuries by testing which muscles work or don't

What are the two major sources of muscle innervation

Spinal nerves and cranial nerves

Where do cranial nerves come from

They arise from the base of the brain and exit through the skull foramina

How much blood does a muscular system get at rest

About 1.24 L/min 1/4 of cardiac output

Why do skeletal muscles need such rich blood flow

Because contracting fiber burns tons of energy and need constant oxygen and nutrients,

- Muscle cells also produce metabolic waste which must removed effectively

What language are most muscle names based on

latin

What do muscle names usually describe

Distinctive aspects like structure location or action

For example oblique means

Diagonal to midline