ap exam4

What are the functions of the muscular system?

Movement, posture, joint stabilization, and heat production.

Origin

The fixed, stationary attachment of the muscle

Belly

The thick, middle part of the muscle

Insertion

The movable attachment where the muscle exerts force

Which part of the muscle is typically still?

Origin is still

Which part moves the bone?

Insertion moves the bone

Tendon

A fibrous connective tissue that connects muscle to bone

Aponeurosis

A flat, sheet-like tendon that muscles

Agonist

The primary mover in an action (e.g., biceps in elbow flexion)

Antagonist

The muscle that opposes the agonist (e.g., triceps in elbow flexion)

What can a muscle’s name tell you?

It can indicate action, location, attachment points, shape/size, number of origins, and fiber direction

How can you remember muscle actions if you forget?

Think about what happens when the muscle shortens or where it is located

Mastication

The process of chewing; involves muscles that move the mandible

What do the pterygoid muscles do that the masseter and temporalis can’t?

They allow side-to-side grinding movements of the jaw

What does the transversus abdominis do?

Stabilizes the core and compresses the abdomen

When the diaphragm contracts, does it move up or down? Do you inhale or exhale?

Moves down → Inhale

What is the role of scapular muscles in shoulder movement?

They stabilize and move the scapula to allow full arm movement

What are the rotator cuff muscles? What bone do they insert on?

SITS Muscles (Supraspinatus, Infraspinatus, Teres Minor, Subscapularis); insert on the humerus

Which muscle is more developed in boxers?

Boxers: Serratus Anterior (punching motion)

Which muscle is more developed in swimmers?

Swimmers: Latissimus Dorsi (pulling motion)

What are the three types of muscle tissue?

Skeletal (voluntary), Cardiac (heart, involuntary), Smooth (organs, involuntary)

Why are skeletal muscle fibers multinucleated?

They form by the fusion of multiple cells during development

Describe the organization of muscle tissue from smallest to largest.

Myofilaments → Myofibrils → Muscle Fiber → Fascicle → Whole Muscle

What makes up thick filaments?

Myosin

What makes up thin filaments

Actin, troponin, tropomyosin

What covers the binding sites on actin?

Tropomyosin covers

What moves the binding sites on actin?

Troponin moves it when calcium binds

What are the key parts of the neuromuscular junction?

Synaptic knob, Synaptic cleft, Motor end plate

Synaptic Knob

End of neuron, releases neurotransmitter

Synaptic cleft

Gap between neuron and muscle

Motor end plate

Part of the muscle that recieves the signal

What ion enters the synaptic knob to trigger neurotransmitter release?

Calcium (Ca²⁺)

What is the neurotransmitter for skeletal muscle contraction?

Acetylcholine (ACh)

What organelle stores calcium in muscle cells?

Sarcoplasmic reticulum

What molecule is needed for myosin to perform a power stroke?

ATP

Motor unit

A motor neuron and all the muscle fibers it controls

What are the three ways muscles generate ATP?

Creatine phosphate system, Anaerobic glycolysis, Aerobic respiration

Creatine phospahte system

Immediate, short-lasting

Anaerobic glycolysis

Uses glucose, no oxygen, short duration)

Aerobic respiration

Uses oxygen, long-lasting

What are the three types of skeletal muscle fibers?

Slow oxidative, Fast glycolytic, Fast oxidative

low oxidative

Endurance, fatigue-resistant

Fast glycolytic

Powerful, fatigues quickly

Fast oxidative

Intermediate power and endurance

What are the two main types of contractions?

Isotonic and Isometric

Isotonic

Muscle changes length

Concentric

Muscle shortens

Eccentric

Muscle lengthens

Isometric

Muscle doesn’t change length

Orbicularis Oculi

Closes eyelid

Orbicularis Oris

Closes and puckers lips

Temporalis

Elevates mandible (chewing)

Sternocleidomastoid

Turns and flexes head

Rectus Abdominis

Flexes spine

Internal/External Obliques

Rotate and flex torso

Transverse Abdominis

Compresses abdomen

Trapezius

Elevates/depresses scapula

Pectoralis Major

Flexes and adducts shoulder

Latissimus Dorsi

Extends and adducts shoulder

Deltoid

Abducts arm

Biceps Brachii

Flexes elbow

Triceps Brachii

Extends elbow

Rectus Femoris

Extends knee, flexes hip

Gastrocnemius

Plantarflexes ankle

Masseter Muscle Origins & Insertions (Examples)

Origin: Zygomatic arch → Insertion: Mandible

Deltoid Muscle Origins & Insertions (Examples)

Origin: Clavicle/scapula → Insertion: Humerus

What determines muscle contraction strength?

Size and number of motor units recruited.

What are the three ways muscles generate ATP?

Creatine phosphate, glycolysis, aerobic respiration.

Which ATP pathway is most immediate but short-lasting?

Creatine phosphate.

Which pathway uses glucose but not oxygen?

Glycolysis.

Which ATP pathway lasts the longest?

Aerobic respiration (needs oxygen).

What brings an electrical impulse deep into the muscle cell?

T-tubules.

What stores calcium in muscle cells?

Sarcoplasmic reticulum.

Which sarcomere structures get smaller when a muscle contracts?

I band and H zone.

Describe muscle tissue organization from myofilaments to whole muscle.

Myofilaments → Myofibrils → Muscle Fibers → Fascicles → Whole Muscle.

What is the sarcolemma?

The plasma membrane of a muscle cell.

What is the sarcoplasm?

The cytoplasm of a muscle cell.

What are the three types of muscle tissue?

Skeletal, cardiac, smooth.

What causes skeletal muscle fibers to be multinucleated?

Fusion of myoblasts during development.

How long are muscle fibers?

Can be several centimeters long.

What do the endomysium, perimysium, and epimysium form when merged?

A tendon.

What do the pterygoid muscles do that the masseter/temporalis can't?

Side-to-side jaw movement.

What does the transversus abdominis do?

Compresses the abdomen, not movement.

When the diaphragm contracts, does it move up or down?

Downward.

Do you inhale or exhale when the diaphragm contracts?

Inhale.

What is the role of scapular muscles in shoulder movement?

Stabilize and assist movement.

What are the rotator cuff muscles?

Supraspinatus, infraspinatus, teres minor, subscapularis.

What bone do all rotator cuff muscles insert on?

Humerus.

Orbicularis Oculi

Orbicularis Oris

Temporalis

Sternocleidomastoid

Rectus Abdominis

Internal Oblique

External Oblique

Transverse Abdominis

Trapezius

Rhomboid Major

Rhomboid Minor

Pectoralis Major