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Biomechanics Exam 1 > Neuromuscular System > Flashcards

Flashcards in Neuromuscular System Deck (53)
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1
Q

What are the three portions of the sensory - output pathway? What is each?

A
  • Sensory input: somatosensory to CNS
  • Central processing: either reflex or brain comes up with a plan
  • Motor output: muscle function
2
Q

Match the following: (afferent / efferent), (sensory / motor).

A
  • Afferent = sensory
  • Efferent = motor
  • “Get the F out”
3
Q

When resting, are nerves a net positive or negative charge?

A

Negative

4
Q

For this class, once an AP starts, when does it stop?

A

Never

5
Q

For muscle contractions, what ion starts the depolarization?

A

Calcium

6
Q

T/F: Muscles AND neurons are excitable.

A

True

7
Q

What are the levels of a muscle going from smallest to biggest?

A
  • Sarcomere
  • Myofibril
  • Fibers
  • Fascicles
  • Muscle
8
Q

What is a muscle cell called?

A

A fiber

9
Q

What are myofibrils?

A
  • Bundles of myofilaments
  • Make up fibers
  • Actin / myosin
10
Q

What is a motor unit?

A
  • A motor neuron and all of the muscle fibers it innervates
  • Can contact as few as 3-5 fibers and as many as 100
11
Q

T/F: Nerves can contact whole muscles.

A
  • False
  • Nerves can only contact portions of a muscle, not the whole muscle
12
Q

What are the two types of muscle fibers?

A
  • Type 1
  • Type 2
13
Q

What are type 1 muscle fibers?

A
  • Slow twitch muscle fibers
  • Oxidative (requires oxygen)
  • Can last longer before fatigue
14
Q

What is the difference between slow and fast twitch muscles?

A

It is the difference on how long it takes for the muscle to fully contract

15
Q

What are type 2 muscle fibers? What are the two types?

A
  • Fast twitch muscle fibers
  • Type 2a (oxidative glycolytic): oxidative glycolytic: a hybrid between fast and slow twitch
  • Type 2b (glycolytic): No O2 required; fatigues fast
16
Q

T/F: Function determines the type of fiber. Give an example?

A
  • True
  • Posture and abs muscles are flexed all day long = they are slow twitch
  • This can alter with age though
17
Q

Can you alter types of fibers due to training?

A

Yes

18
Q

What are the three main rules of how muscles work?

A
  • They can only contract and relax
  • Muscles only work on a joint they cross
  • Muscles work best in the direction of their fibers
19
Q

What are muscles that only cross one joint best for? Two joints?

A
  • 1: strength, 1 function
  • 2: stabilizing, multiple functions
20
Q

What is the agonist muscle?

A
  • The “prime mover”
  • The main muscle that creates a certain motion
21
Q

What is the synergist muscle?

A
  • A muscle that assists the agonist in generating movement force
  • It has another purpose besides helping the agonist
22
Q

What is the antagonist muscle?

A
  • A muscle that does the opposite action of the agonist
  • Usually placed on the opposite side of the joint
  • Usually inactive in a motion
23
Q

What is the neutralizer muscle?

A
  • A muscle that can get rid of a portion of a motion that isn’t wanted
  • Ex.: different muscles allow the biceps to flex with different wrist placements
24
Q

What is the stabilizer / fixater muscle?

A

A muscle that helps provide stability on an area or joint

25
Q

What are the three types of muscle contractions?

A
  • Concentric
  • Eccentric
  • Isometric
26
Q

What is a concentric muscle contraction?

A

When a muscle shortens in length during a contraction

27
Q

What is an isometric muscle contraction?

A

When there is no length change during flexion

28
Q

What is an eccentric muscle contraction? When is it often used?

A
  • When the muscle is active but insertion and origin spread apart
  • During changing directions or braking
29
Q

What are closed kinetic chains? What is an example?

A
  • Aka “CKC”
  • Movements where the DISTAL segment is fixed…
  • And the PROXIMAL segment moves
  • Squats
  • Push ups
30
Q

What are open kinetic chains? What is an example?

A
  • Aka “OKC”
  • Movements where the PROXIMAL segment is fixed…
  • And the DISTAL segment moves
  • Throwing
31
Q

What is tetanus?

A

Full contraction of a muscle

32
Q

What is active tension recruitment? Why does the body use this?

A
  • The body uses small neurons before it starts to use large ones
  • The body uses small motor units before it spends bigger ones
  • The body uses type 1 (long term) before type 2 fibers (fast twitch)
  • This allows only energy needed to complete a task
33
Q

What is the main determinant for if an action is active or passive?

A

Whether or not it uses ATP

34
Q

What is rate coding and what does it have to do with graded muscle contractions?

A
  • The frequency of APs
  • 1 action potential is one muscle twitch
  • When the twitches go back to back faster, there is more force (vise versa)
  • This allows for no muscle waste
35
Q

What is synchronization?

A
  • Where the body learns how to turn on multiple motor units at the same time
  • Simultaneously firing the motor neurons
36
Q

What is passive force production?

A
  • Aka passive tension
  • This tension is produced by the fascia layers of the body and the tendons and ligaments (the passive elastic components)
37
Q

How does the physiological length-tension relationship of a muscle impacts performance of that muscle (amount of force production)?

A
  • When the muscle gets larger or shorter than its resting length, less actin and myosin can overlap and there will be less force production
  • Passive tension: stretching and bounce back; there is less when the muscle is short
38
Q

What is passive insufficiency?

A
  • Deals with multi-joint muscles
  • The inability of a muscle to lengthen passively and allow full range of motion at all joints it crosses
  • The range of motion is still not fully there, but the muscle won’t allow any further movement
39
Q

What is active insufficiency?

A
  • Deals with the active piece of multi-joint muscles
  • This deals with when a muscle can’t contract any further to allow range of motion of all the joints it crosses
  • The muscle is fully contracted, but there is still more range of motion
40
Q

How does the tenodesis grasp work?

A
  • Passive sufficiency of flexors causes a grasping motion when the wrist is extended
  • Passive sufficiency of extensors causes the hand to let go when the wrist is flexed
41
Q

How does the speed of concentric contractions affect force development? Why?

A
  • Slow speed yields higher force development
  • Vise versa
  • Due to slower speed, there will be more time to recruit more motor units and actin and myosin will have more time for cross-bridge formation
42
Q

How does the speed of eccentric contractions affect force development? Why?

A
  • Force production increases with increased speed of eccentrics to a point
  • Elasticity comes into affect
  • Cross bridges of actin and myosin is easily to ratchet down than flexing
43
Q

What are reflexes?

A
  • INVOLUNTARY reaction due to a stimulus
  • Predictable behavior
44
Q

What are Golgi Tendon Organs (GTO)? What do they do?

A
  • Small sensors woven into tendons at muscle tendon junctions
  • Responds to a stretch of a muscle (afferent) and collagen fibers due to increased tension
  • Protect the tendons from stretching too far
45
Q

***What is the response (efferent stimulus) of a GTO?

A
  • Autogenic inhabitation: turns off the muscle being stretched
  • Reciprocal excitation: turns on the opposite of the muscle stretched
46
Q

What are muscle spindles?

A
  • Small receptors woven into muscle fibers
  • Responds to speed and length of a stretch (afferent)
  • Involved in myotatic stretch reflexes
47
Q

***What is the response (efferent stimulus) of a muscle spindle?

A
  • Autogenic excitation: turns on the stretched muscle
  • Reciprocal inhabitation: turns off the opposite of the stretched muscle
48
Q

T/F: Muscle spindles and GTOs work together.

A

True

49
Q

What is the myotatic reflex?

A

Stretch reflex

50
Q

What is load compensation? How does it work?

A
  • Regulating functional muscle length via muscle spindles
  • Muscle spindle stretches and then body compensates via muscle contraction
51
Q

What is the stretch-shorten cycle?

A
  • Think springs
  • For there to be a great force production there needs to be: active contraction, passive contraction, neurological work
  • Actively loading + passively stretching (to get passive tension) + neurological (fast = engages spindles)
52
Q

What is the size principle?

A

Refers to the principle of which smaller motor units are recruited before large ones so the body doesn’t waste any energy

53
Q

What is the active aspect to contractions?

A

The working of actin and myosin