Muscles

Question 1

Types of muscle tissue

Answer 1

All very long because during development the cells fuse together to form long strands.

1. Smooth muscle cells
2. Skeletal muscle cells
3. Cardiac muscle cells

Question 2

Purpose of skeletal muscle tissue

Answer 2

1. form muscles that attach to and move the skeleton under voluntary control
2. Some skeletal muscles prevent the movement to maintain body position and achieve desired motion
3. Stabilize joints

Question 3

Some specific actions of skeletal muscles

Answer 3

• move eyeball
• facial expression
• respiration
• straining (urination, defecation, parturition)
• urinary bladder and bowel continence
• Twitch or wrinkle skin (superficial fascia- humans don’t have this)

Question 4

Sarcomere

Answer 4

The basic contractile unit of the muscle fibre.

• Composed of actin and myosin
• Myosin attach to actin, pulling it towards the center and if strong enough, the sarcomeres will shorten

Question 5

Muscle fibers

Answer 5

Multinucleate muscle cell surrounded by endomysium

Question 6

Fascicle

Answer 6

Group of fibers surrounded by perimysium

Question 7

What surrounds the entire muscle?

Answer 7

Epimysium surrounds the entire muscle and merges with deep fascia

Question 8

Tendons

Answer 8

• Attach muscle to bone
• Don’t contract like muscles
• Viscoelastic

Question 9

Viscoelastic

Answer 9

Elastic= return to form after being stretched

Visco= get stiff when force applied

Question 10

Aponeurosis

Answer 10

Broad, flat tendon

• Made up of both parallel bundles of collagen fibers and bundles that split away and run obliquely to the primary axis of elongation. This allows for them to withstand stretching forces in multiple directions

Question 11

What kind of tissue are tendons and ligaments?

Answer 11

Dense regular connective tissue (so have fibers running in same direction)

Question 12

What are some ways that tendons are protected?

Answer 12

• sesamoid cartilage or bone
• bursa (fluid filled cushions)
• Synovial sheath (similar to a bursa but wraps around the tendon)

Question 13

What is the most powerful contraction?

Answer 13

Lengthening

Question 14

Origin vs. insertion

Answer 14

Origin= least movable attachment
Insertion= most movable attachment

Question 15

Agonist

Answer 15

• Muscle that provides most of the force to cause a movement
• A prime mover

Question 16

Synergist

Answer 16

Muscle causes the same movement as an agonist muscle

Question 17

Antagonist

Answer 17

Muscle resists that movement causes the opposite movement

Ex. Triceps are antagonist to bicep movement

Question 18

Neutralizer

Answer 18

Muscle cancels out extra motion produced by an agonist muscle so that the movement occurs in the desired plane

Ex. hamstring muscles- some cancel others out to ensure that leg does not move sideways instead of straight

Question 19

Fixator

Answer 19

muscle that stabilizes the origin of an agonist muscle to help the agonist muscle function effectively

Ex. fixators in shoulder stabilize origin of agonist so that it moves properly

Question 20

Extrinsic muscles vs. intrinsic muscles

Answer 20

Extrinsic= also called axioappendicular muscles, and includes all muscles going from axial skeleton to the appendage

Intrinsic= appendicular muscles and include muscles within the appendage

Question 21

synsarcosis

Answer 21

A connection between parts of the skeleton formed by muscles alone

Question 22

Connection between thoracic girdle and axial skeleton

Answer 22

There is no bony link. Connection is a synsarcosis.

Allows the scapula to move cranially and caudally to increase the stride length.

Question 23

Muscle actions of the extrinsic thoracic appendicular muscles

Answer 23

1. Protraction- limb outstretched forward
2. Retraction- limb outstretched backward
3. Rotate scapula- needed for moving in any direction
4. Elevation
5. Depression
6. Draw scapula against thorax
7. support trunk
8. Abduction
9. Adduction

Question 24

Muscle actions of the intrinsic thoracic appendicular muscles

Answer 24

1. Medial rotation
2. Lateral rotation
3. Abduction
4. Adduction
5. Pronation
6. Supination