EXSC 440 Exam 3 L

Question 1

Slow twitch

Answer 1

type 1, high myoglobin

Question 2

Fast twitch

Answer 2

white, low myoglobin content. Type 2a or 2b

Question 3

Smooth muscle

Answer 3

autonomic nervous system
non-striated, not organized in sarcomeres
single oval centrally located nucleus

Question 4

Cardiac muscle

Answer 4

regulated by intrinsic fibers, hormones, and ANS
striated, single centrally nucleus
intercalated discs

contracts 10 to 15 times longer

Question 5

Muscle composition

Answer 5

(smallest)
sarcomere
myofibril

muscle fiber –> covered w/endomysium, held together with fascia

fasciculi–> covered by perimysium

muscle–> covered by epimysium

Question 6

sarcomere order

Answer 6

Z disc
I band
A band
H zone
M line

Question 7

sarcomeres composition

Answer 7

actin or thin myofilaments, are made of troponin and tropomyosin. Troponin removes the tropomyosin so that the myosin/thick filament can bind to the actin head

Question 8

sarcoplasmic reticulum

Answer 8

extends throughout the cell and surrounds each myofibril

stores and releases calcium

Question 9

Transverse tubules (t-tubules)

Answer 9

run from the cell membrane (sacrolemma) to deep within the cell and perpendicular to the fibers

spread polarization from membrane to interior of cell, causes release of calcium from reticulum

Question 10

sarcolemma

Answer 10

cell membrane

Question 11

sarcoplasm

Answer 11

intracellular material

Question 12

aponeurosis

Answer 12

fibrous or membranous, closely packed, parallel collagenous bundles that provide strength and support to structures

Question 13

fusiform characteristics

Answer 13

The fibers run parallel with the longitudinal axis of the muscle
100% of the muscle contraction distance contributes to moving the attachments
Have few fibers per unit area
Have longer fibers and produce greater ROM but less force

Question 14

fusiform muscle

Answer 14

biceps brachii

Question 15

Pennate characteristics

Answer 15

The fibers run obliquely
Produce less ROM change for a given distance but a greater force
Have shorter fibers but more per unit area
The greater the angle the muscle fiber is to the longitudinal axis of the muscle, the smaller is the effective shortening component

Question 16

pennate muscle

Answer 16

uni = tibialis post
bi = gastrocnemius, rectus femoris

Question 17

disadvantages of pennate muscle

Answer 17

form an angle at 30 degrees, can only transmit a portion of force
fiber shortening is greater than lengthening
lifting height is increased b/c physiological cross section is larger than anatomic cross section

Question 18

Non-pennate advantages

Answer 18

fibers run longitudinal, transmit all force to tendon
max shortening and actual are about the same
both cross sections are the same

Question 19

Longitudinal muscle

Answer 19

sartorius

Question 20

Radiate muscle

Answer 20

gluteus medius

pec major

Question 21

Circular muscle

Answer 21

orbicular oculi

Question 22

Muscle shapes

Answer 22

longitudinal
fusiform
radiate
unipennate
bipennate
circular

Question 23

how are muscles named?

Answer 23

shape
action
location
attachments
# of parts
size
fiber orientation

Question 24

What determines what action a muscle performs?

Answer 24

Where the muscle or its tendon(s) cross the joint it is acting upon

The relationship of the crossing the joint with the axis of rotation of the joint

Question 25

What determines how well a muscle does what it does?

Answer 25

size and angle of pull!!! ``` recruitment of motor units tension firing frequency/how well they synch length of muscle velocity of shortening ```

Question 26

Advantages to 2 joint muscles

Answer 26

Tend to pull the bony attachments toward the center of the muscle Tend to produce motion in all the articulations that it passes Two joint muscles are considered to be more efficient synchronous movement less complex innervation greater ROM b/c of less muscle mass pulley action of muscles

Question 27

Examples of 2 joint muscles

Answer 27

Hip and Knee Sartorius, rectus femoris, biceps femoris, semitendinosis, semimembranosus, gracilis knee and ankle gastrocnemius, plantaris

Question 28

disadvantages to 2 joint muscles

Answer 28

Active and passive insufficiency

Question 29

Lombard’s paradox

Answer 29

Involves the rectus femoris and the hamstrings When rising to stand from a sitting or squatting position, both the hamstrings and quadriceps contract at the same time, despite them being antagonists to each other.

Question 30

Lever arm

Answer 30

distance from center of rotation of the joint to the point of attachment of the muscle

Question 31

lever system

Answer 31

axis of rotation motive torques resistive torques

Question 32

1st class levers

Answer 32

fulcrum or axis of rotation is in between the motive and resistive torques. Common examples: teeter-totter, crowbar, pliers, scissors. Unusual in the musculoskeletal system Plantar flexion on a universal machine

Question 33

2nd class lever

Answer 33

the resistive torque is between the fulcrum and the motive torque Wheel barrow, nutcracker, door Unusual in the musculoskeletal system A push-up Extension of the metatarsal phalangeal joint while standing is an example of a second class lever

Question 34

3rd class lever

Answer 34

the motive torque is between the fulcrum and the resistive torque Most of the musculoskeletal levers in the body are 3rd class

Question 35

Mechanical advantage

Answer 35

ratio of resistive force to motive force/effort RF > MF = 3rd MF > RF = 2nd

Question 36

RF vs MF

Answer 36

RF = MF --> static MF > RF = concentric MF < RF = eccentric

Question 37

Trendelenburg gait

Answer 37

When there is paralysis or marked weakness of the gluteus medius, there will be a gluteus medius limp in walking. This consists of displacement of the trunk laterally toward the side of weakness, shifting the center of gravity in such a way that the body can be balanced over the extremity with minimal muscular support at the hip

Question 38

Loss of hamstrings

Answer 38

Results in a profound loss of flexion at knee Who could take care of knee flex instead? Gastrocnemius (2-joint muscle) is a stronger ankle PF Only a weakening of extension at hip

Question 39

illiopsoas test

Answer 39

When intra-abdominal inflammation is suspected an iliopsoas test is performed. Because of proximity of the iliopsoas to organs such as the kidneys, appendix, and pancreas, movement of the muscle usually results in pain when any

Question 40

kicking muscle

Answer 40

rectus femoris particularly efficient in movements combining the knee extension and hip flexion when starting from hip hyperextension. easily injured at AIIS, avulsion

Question 41

loss of quads

Answer 41

Results in complete loss of active extension at the knee If quads are paralyzed, the person usually presses on the distal end of the thigh during walking to prevent inadvertent flexion of the knee.

Question 42

loss of sartorius

Answer 42

Virtually no active deficit | Gait is fine

Question 43

Chondromalacia Patellae

Answer 43

“runner’s knee” is common in marathon runners and basketball players, due to overstressing the knee and/or quadriceps imbalance causes breakdown of cartilage under the patella

Question 44

anterior compartment of leg

Answer 44

Most susceptible to compartment syndromes because it’s confined by unyielding structures on three sides (two bones and the interosseous membrane) Important during gait

Question 45

Calcaneal tendon rupture

Answer 45

More common in less conditioned people with a history of tendinitis. Forceful push-off – plantarflexion with knee extension Audible snap followed by calf pain and sudden dorsiflexion Ambulation is only possible by rolling over an externally rotated limb.

Question 46

Plantar fascia

Answer 46

Longitudinally arranged bundles of dense fibrous connective tissue Tough, dense, elongated Helps protect the sole from injury Helps protect the longitudinal arches of the foot

Question 47

Plantar fasciitis

Answer 47

Straining and inflammation of the plantar aponeurosis Often from Running or high impact aerobics Inappropriate shoes, tight Achilles tendon, flat arches More common in the hindfoot and medial aspect of the foot Usually most painful when starting to use right after rest Common treatments:Ice, stretch calve muscles, supportive shoes