Unit 3 study guide chp9

Which muscle shape has fibers running straight and evenly spaced, often long?

Parallel. (ex sartorious)

Which muscle shape has fibers radiating from a broad area to a single tendon?

A: Convergent (e.g. pectoralis major).

Q: Which muscle shape surrounds an opening and controls entrances/exits?

A: Circular (sphincters).

Q: What is a pennate muscle?

A: A muscle with fibers attached at an angle to a central tendon (feather-like). ex. rectus femoris

Q: What does "fusiform" mean in terms of muscle shape?

A: Muscle is thick in the middle and tapered at both ends (e.g. biceps brachii).

Q: Which muscle shape twists as it moves from origin to insertion?

A: Spiral (ex. supinator).

Q: What are the 5 major functions of skeletal muscle?

A: Movement, posture, joint stabilization, heat production, and support of soft tissues.

Q: How do skeletal muscles help maintain body temperature?

A: Through heat production during contractions (shivering = muscle-generated heat).

Q: How do skeletal muscles assist with posture and joint stability?

A: Continuous partial contractions (muscle tone) keep the body upright and stabilize joints.

Q: What does a muscle’s name tell you if it includes “brachii” or “femoris”?

A: It tells you the location:

• Brachii = arm

• Femoris = thigh

Q: What do names like maximus, longus, and brevis, flexor, adductor, rectus and oblique describe?

A: The size or length of the muscle:

• Maximus = largest

• Longus = long

• Brevis = short

• Rectus = straight

• Oblique = angled/diagonal

• Flexor = flexes a joint

• Adductor = pulls toward the body

Q: What is the agonist in a movement?

A: The prime mover – the main muscle responsible for the action (e.g. biceps brachii during elbow flexion).

Q: What is the antagonist in a movement?

A: The muscle that opposes the agonist

• Relaxes when the agonist works, and vice versa

• Helps control or stop the motion

Q: What is a synergist and a fixator muscle?

• Synergist helps the agonist.

• Fixator holds a bone steady for smooth movement. (does its job without the body wobbling or shifting all over the place.)

Q: What is a first-class lever, and where is it found in the body?

• Fulcrum is between the force and load (like a seesaw)

• Example: Neck extension
  • Fulcrum = atlanto-occipital joint
  • Force = neck muscles pulling down
  • Load = weight of the head

• Power: Moderate

• Range of motion: Moderate

Q: What is a second-class lever, and where is it found in the body?

• Load is between the fulcrum and force (like a wheelbarrow)

• Example: Plantar flexion (tiptoeing)
  • Fulcrum = ball of the foot
  • Load = body weight
  • Force = calf muscles (gastrocnemius/soleus) pulling heel up

• Power: High

• Range of motion: Low

Q: What is a third-class lever, and where is it found in the body?

• Force is between the fulcrum and load (like a shovel)

• Example: Elbow flexion (biceps curl)
  • Fulcrum = elbow joint
  • Force = biceps pulling on radius
  • Load = weight in hand

• Power: Low

• Range of motion: High

Q: What muscles help you climb stairs?

• Agonists: Glutes & quads

• Synergists: Hip flexors

• Fixators: Core

• Antagonists: Hamstrings

Q: What muscles help with drinking?

• Agonist: Biceps

• Synergist: Deltoid

• Fixators: Rotator cuff

• Antagonist: Triceps

Q: What muscles work during walking & eating?

• Walking: Glutes, hamstrings, quads, calves, core

• Eating: Masseter, temporalis, tongue, neck stabilizers