1.2: muscles in motion

Question 1

Tendons

Answer 1

Fibrous tissue that attaches muscle to bone

Question 1

Actin (filaments)

Answer 1

Protein that makes up the thin filaments; contains troponin

Question 2

Myosin (filaments)

Answer 2

Protein that makes up the thick filaments

Question 3

Muscle organizational level

Answer 3

Muscles are made of fascicles.
Fascicles are made of individual muscle cells.
Individual muscle cells are made of myofibrils.
Myofibrils are made of sarcomeres in a long line.
Sarcomeres are made of myofilaments: thick filaments and thin filaments.

Question 4

Steps of muscle contraction

Answer 4

1) Acetylcholine diffuses across the synaptic cleft (of the neuron) and attaches to receptors of the muscle cell.
2) The neurotransmitter is converted to an action-potential, traveling down the sarcolemma (sheath around muscle fibers) and T-tubules.
3) This causes the sarcoplasmic reticulum to release calcium to the muscle cells.
4) The calcium binds to proteins called troponin on the muscle cells (AKA muscle fibers). Troponin proteins are found on the actin [thin] filaments.
5) This signals for the tropomyosin protein to move so that the myosin head can attach.
6) The myosin head (energized by ADP + Pi) attaches to the actin.
7) The myosin head pulls the actin and myosin past each other (sliding filament theory).
8) An ATP eventually binds to the myosin head, causing it to detach from actin and for the muscle to relax.

Question 5

T-tubules

Answer 5

Extensions of the cell membrane that travel throughout the cell, allowing action-potentials to travel to muscle fibers,causing the sarcoplasmic reticulum to release calcium.

Question 6

Muscle fiber

Answer 6

Skeletal muscle cell

Question 7

Fascicle

Answer 7

Bundle of muscle fibers (muscle cells)

Question 8

Perimyseum

Answer 8

Surrounds fascicles

Question 9

Sarcolemma

Answer 9

Cell membrane of each muscle cell / fiber

Question 10

Endomysium

Answer 10

Connective tissue found around each muscle cell (on top of the cell membrane / sarcolemma)
Endo meaning innermost

Question 11

Epimysium

Answer 11

Connective tissue surrounding the entire muscle (epi meaning outermost)

Question 12

Muscle rules

Answer 12

1) They must have at least 2 attachments (at least 1 insertion and 1 origin)
2) They must cross at least 1 joint
3) Muscles can only contract (shorten)
3) Insertion is the attachment that moves; origin remains stationary
4) Muscles that decrease angles between ventral surfaces are flexors; muscles that increase these angles are extensors
5) Muscles work in opposing pairs
6) Muscle striations show the direction of the pull

Question 13

Naming muscles

Answer 13

1) Shape
2) Relative size
3) Location (regional terms)
4) Action (flexor / extensor)
5) Origin and insertion (which bones they attach to)
6) Number of origins
7) Direction of muscle fibers

Question 14

Intercostals origin

Answer 14

Lower border of a rib

Question 15

Intercostals insertion

Answer 15

Upper border of the rib below

Question 16

Intercostals action

Answer 16

Allow the rib cage to expand/relax

Question 17

Pectoralis minor origin

Answer 17

3rd-5th ribs

Question 18

Pectoralis minor insertion

Answer 18

Scapula corocoid process

Question 19

Pectoralis minor action

Answer 19

Internal / downward scapula rotation (pulls arm forward and down)

Question 20

Pectoralis major origin

Answer 20

Clavicular head: clavicle
Sternal head: 1, 2, and 3
Abdominal head: ribs 4, 5, and 6

Question 21

Pectoralis major insertion

Answer 21

All 3 heads insert into the lateralhumerus

Question 22

Pectoralis major action

Answer 22

Internal humerus rotation

Question 23

Serratus anterior origin

Answer 23

Lateral parts of ribs 1-8

Question 24

Serratus anterior insertion

Answer 24

Anterior, medial scapula (shoulder blade)

Question 25

Serratus anterior action

Answer 25

Arm elevation (90 degrees & upward)

Question 26

Fibrous joint

Answer 26

Immovable joint that connects bones

Question 27

Cartilaginous joint

Answer 27

Joint with some motion (hyaline cartilage)

Question 28

Synovial joint

Answer 28

Movable joint containing synovial fluid

Question 29

Ligaments

Answer 29

Fibrous connective tissue that connects bones to other bones

Question 30

Plantar flexion

Answer 30

Flexion at the ankle

Question 31

Dorsiflexion

Answer 31

AKA plantar extension at the ankle (returns flexion movement to normal position)

Question 32

Articular (hyaline) cartilage

Answer 32

Covers ends of bones (AKA condyles) and cushions joints

Question 33

Elastic cartilage

Answer 33

Most flexible cartilage, allowing for lots of movement (ear, respiratory tract)

Question 34

Fibrocartilage

Answer 34

Strongest type of cartilage (supports body, ie in the intervertebral discs)

Question 35

Pivot joint

Answer 35

1 bone rotates within a ring attaching it to another bone; only the first bone rotates.

Question 36

Hinge joint

Answer 36

Rounded shape of one bone and U shape of another rotate against each other (flexion/extension)

Question 37

Saddle joint

Answer 37

Concave surface of one bone and convex surface of another; allow for flexion/extension AND abduct/adduction (different from hinge)

Question 38

Plane joint

Answer 38

Between flat surfaces of 2 or more bones; bones don’t rotate but slide past each other. Typically have limited range of movement

Question 39

Condyloid joint

Answer 39

Oval depression and oval surface of bones; allow for abduction/adduction, flexion/extension (like saddle joint), but also circumduction in some cases

Question 40

Ball and socket joint

Answer 40

Spherical head of 1 bone rotates in the cup of another (widest ROM, allowing for all movements. Only hip and shoulder joint in humans)

Question 41

Posterior drawer test

Answer 41

The tibia is pushed away from the PT; assesses the PCL

Question 42

Anterior drawer test

Answer 42

The tibia is pulled toward the PT; assesses the ACL

Question 43

Valgus

Answer 43

The tibia is rotated outward (laterally); assesses the MCL

Question 44

Varus

Answer 44

The tibia is rotated inwardly (medially); assesses the LCL