Lecture 15 - Myology

Question 1

What is myology?

Answer 1

• the study of muscles
• refers to skeletal muscle tissue

Question 2

What type of unit is skeletal muscle?

Answer 2

• a motor unit
• one motor neuron plus all the muscle fibres it innervates

Question 3

What’s are 2 types of innervation ratio’s?

Answer 3

• fine motor movement
• gross motor movement

Question 4

What is fine motor movement?

Answer 4

• a small innervation ratio
• each motor neuron innervates a small number of muscle fibres
• i.e., 10-100

Question 5

What is gross motor movement?

Answer 5

• a higher innervation ratio
• each motor neuron innervates lots of muscle fibres
• i.e., 1000

Question 6

What are tendons?

Answer 6

• Attaches muscle to bone, I.e., tuberosities, processes, etc
• Spreads out & attaches at multiple points
• Connective tissue acts as a harness which allows muscle to transmit force & “pull” on a bone
• can also be an aponeuroses

Question 7

What is aponeuroses ?

Answer 7

• a flat, sheet-like (not cylindrical) tendon found throughout the body
• spreads out & provide an attachment point for muscles to connect to bone
• important for muscle movement & posture

Question 8

What are levers? What are the 3 types of levers?

Answer 8

• Muscles & their tendinous attachments & their relationship with the joints they cross result in three classes of levers - 1, 2 & 3
• Differ in the arrangement of the three variables:
• F = force (energy)
• A = axis (fulcrum)
• R = resistance (load)

Question 9

What is a class 1 (FAR) lever?

Answer 9

• represents a see-saw
• Human body - Atlanto-occipital joint in the body
• Force/Energy = posterior neck muscles
• Axis/Fulcrum = cervical spine
• Resistance = weight of anterior skull

Question 10

What is a class 2 (FRA) lever?

Answer 10

• represents a wheelbarrow
• Human Body - Plantar Flexion at the ankle joint
• Force/Energy = calf muscles
• Resistance = body weight
• Axis/Fulcrum = MTP joints

Question 11

What is a class 3 (AFR) lever?

Answer 11

• Most common levers in the human body, gives us an advantage of speed over strength
• represents tweezers, nail clippers
• Human Body - elbow joint when lifting a book
• Axis/Fulcrum = elbow joint
• Force/Energy = biceps muscle
• Resistance = weight resting in hand

Question 12

What is skeletal muscle?

Answer 12

• 1 muscle fibre = 1 cell
• it is Under voluntary control; Nerves control the muscle
• Each muscle fibre must be innervated in order to have the ability to contract

Question 13

How is muscle fibre structured?

Answer 13

• covered by delicate connective tissue called the endomysium
• Bundles of fibers are grouped together in the perimysium to form a fascicle
• Entire muscle (several bundles/fascicles) is bound by the epimysium

Question 14

What is the importance of muscle shapes?

Answer 14

• Different arrangements relative to the axis of force generation
• Determines functional properties of the muscle

Question 15

What are the 6 different shapes of muscle?

Answer 15

• flat
• convergent
• circular
• fusiform/parallel
• pennate
• quadrate

Question 16

What is a flat muscle?

Answer 16

• parallel fibers with an aponeuroses
• i.e., Rectus abdominus

Question 17

What is a convergent muscle?

Answer 17

• arise from broad area to converge to form a single tendon
• i.e., pectoralis major

Question 18

What is a pennate muscle?

Answer 18

• feather-like in the arrangement of the fascicles
• can be uni, bi, or multi-axial
• i.e., quadriceps femoris

Question 19

What is a circular muscle?

Answer 19

• surround a body opening or orifice
• i.e., orbicularis oris

Question 20

What is a fusiform/parallel muscle?

Answer 20

• spindle shaped with round, thick belly & tapered ends
• i.e., biceps brachii

Question 21

What is a quadrate muscle?

Answer 21

• four equal sides
• i.e., Rectus abdominus

Question 22

What are the 4 types of muscle contractions?

Answer 22

• isometric
• isotonic
• concentric
• eccentric

Question 23

What is isometric/isotonic contractions?

Answer 23

• isometric = contraction with no movement; i.e., holding the weight at the top
• isotonic = contraction with movement; i.e., bicep curl

Question 24

What is concentric/eccentric contractions?

Answer 24

• concentric = movement that shortens the muscle; i.e., upward motion of a bicep curl
• eccentric = movement that extends the muscle; i.e., lowering phase of a bicep curl

Question 25

What is agonist/antagonist ?

Answer 25

• agonist = the prime mover; the primary muscle creating a concentric movement
• antagonist = opposing muscle to the agonist, inactive while the agonist is contracting

Question 26

What are fixators?

Answer 26

• Steadies proximal part of a limb throughout an isometric contraction while movement happens distally
• I.e., stabilize the scapulae during pushups

Question 27

What are synergists?

Answer 27

• complements the action of the prime mover

Question 28

How can you locate muscles?

Answer 28

• The name of a muscle usually tells us something about its shape, action, location or it is derived from a Latin root
• i.e., Supraspinatus (above the spine), subscapularis (below the scapula)

Question 29

What are the divisions of muscles?

Answer 29

• Biceps = (2), Triceps = (3), Quadriceps = (4)
• “Ceps” = heads

Question 30

What are the length/size of muscles?

Answer 30

• Longus = (long)
• Brevis = (short)
• Magnus = (large)

Question 31

What is muscle attachment?

Answer 31

• A muscle is described in terms of its attachments to two bones & the action on the joint(s) it crosses

Question 32

What is origin/insertion/main action?

Answer 32

• origin = the proximal attachment (where it begins)
• insertion = distal attachment (where it ends)
• main action = naming the joint & movement