The Muscular System - ANIM1020

Flashcards covering muscle tissue types, anatomy, naming, fiber types, specific muscle functions, growth, and adaptations for locomotion based on the provided lecture notes.

What is the primary function of muscle tissue?

To contract and provide movement to different parts of the body.

Which nervous system voluntarily controls skeletal muscle?

The somatic nervous system.

Which nervous system involuntarily controls smooth and cardiac muscle tissues?

The autonomic nervous system.

Where is skeletal muscle primarily found?

Attached to the skeleton.

What is the appearance of skeletal muscle fibers under a microscope?

They run in parallel tracts, are multinucleated, and heavily striated.

Where is smooth muscle found in the body?

In the lining of internal organs (e.g., GI tract, uterus, blood vessels, eyes).

What is the primary function of smooth muscle?

It controls the involuntary constriction of internal regions, such as peristalsis or vasoconstriction.

Describe the appearance of smooth muscle fibers.

They are not striated, have a spindle shape, and each fiber contains a single central nucleus.

Where is cardiac muscle found?

Exclusively in the heart.

What is the primary function of cardiac muscle?

Responsible for the rhythmic contraction of the heart (heartbeat).

Describe the appearance of cardiac muscle fibers.

They are branching, intercalated, lightly striated, and have a single nucleus per fiber.

In muscle anatomy, what is the 'origin' of a muscle?

The end of the muscle that moves the least.

In muscle anatomy, what is the 'insertion' of a muscle?

The end of the muscle that moves the most.

Why do skeletal muscles come in pairs, known as antagonistic muscles?

Because muscles can only contract and relax, they can only pull on bones and cannot push them back.

What are some criteria used to name skeletal muscles?

Shape, size, fiber direction, location, number of origins, or action.

If a muscle is named 'rectus', what does this indicate about its fiber direction?

The fibers run straight.

What does 'brevis' or 'longus' in a muscle name indicate?

Its length (short or long, respectively).

What does 'quadriceps' in a muscle name indicate?

It has four origins.

What action is associated with 'flexor' muscles?

They decrease the angle at a joint.

Describe fusiform muscles.

Long and thin, often crossing hinge joints, assisting mainly in flexion and extension with one direction of pull.

What is a characteristic of convergent muscles?

They have a single connection at one end and a broader connection at the other, allowing a wide range of movement.

What structural feature gives pennate muscles more strength compared to fusiform muscles?

Short fibers that attach along greater lengths of bone.

What are Type I muscle fibers also known as, and what is their primary metabolic capacity?

Slow-twitch fibers; high capacity for oxidative metabolism.

Are Type I muscle fibers fatigue-resistant, and why?

Yes, they are fatigue-resistant due to a rich supply of mitochondria, abundant myoglobin (red color), and numerous blood vessels ensuring oxygen supply.

What type of activities are Type I muscle fibers engaged in?

Endurance activities.

What are Type IIX muscle fibers also known as, and what is their primary metabolic reliance?

Fast-twitch fibers; predominantly anaerobic glycolytic metabolism.

When are Type IIX muscle fibers primarily activated?

During high-intensity, short-duration activities requiring rapid, forceful contractions.

How do Type IIA muscle fibers generate energy, and what does this allow them to do?

They use both aerobic (oxidative) and anaerobic (glycolytic) metabolism, making them versatile for activities requiring a balance of strength and endurance.

What is the primary action of the Gluteals?

Extend the hip.

What is the primary action of the Masseter muscle?

Elevates the mandible and controls facial expressions.

Which muscle is a major retractor of the arm?

Latissimus Dorsi.

What is the function of the Triceps Brachii?

Extends the elbow and flexes the shoulder.

What is the function of the Biceps Brachii?

Flexor of the forearm.

What is the difference between epaxial and hypaxial muscles of the vertebral column?

Epaxial muscles sit above the transverse processes and extend the spine; hypaxial muscles sit below the transverse processes and flex the neck and tail.

What is the function of the Rectus Abdominis?

Supports the abdominal wall and ventrally flexes the abdomen.

What is the function of the Gastrocnemius and Soleus muscles?

Flexes the knee/stifle and extends the tarsus.

According to the notes, what is 'growth'?

An increase in the structure of the animal and a progressive increase in size until complete physical development.

What is 'mature weight'?

The genetically controlled size an animal will attain if there are no constraints on its growth.

What is 'compensatory growth'?

A natural occurrence where cattle undergo accelerated growth and enhanced feed efficiency after a period of dietary restriction when subsequently offered higher nutrition.

What is 'marbling' in beef, and what is its effect on eating quality?

Visible unsaturated intramuscular fat that accumulates within muscle fibers; it positively affects tenderness, juiciness, and flavor by making the meat softer and easier to chew.

What are the specific muscular adaptations of eagles for aerial locomotion?

Powerful pectoral muscles (especially pectoralis major) for strong wingbeats, gliding, and soaring.

What muscular adaptations do squirrels have for arboreal locomotion?

Strong and flexible limb muscles (flexor and extensor) for climbing and leaping, and well-developed forelimb muscles for gripping and pulling.

How are a shark's muscles adapted for aquatic locomotion?

Powerful myotomal muscles arranged in W-shaped blocks along their bodies that contract sequentially to produce wave-like movements for efficient propulsion.

What muscular adaptations do wombats have for fossorial locomotion?

Powerful shoulder and forelimb muscles (deltoids and triceps) and short, muscular limbs for digging extensive burrows.

What muscular adaptations do greyhounds have for cursorial locomotion?

Long, lean muscles, especially in their hind legs (gluteal and quadriceps), for explosive power, rapid acceleration, and sustained high-speed running.