Lecture 1 - Myology Flashcards
What is Myology?
- the study of muscles
What is the skeletal muscle?
- 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
What type of unit is the skeletal muscle?
- it is a Motor unit
- One motor neuron + all muscle fibers innervated by that nerve
- “all or nothing” response
What is muscle fiber structure ?
- Muscle fiber is 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
What are tendons ?
- Attaches muscle to bone; Tuberosities & processes
- Can also be an aponeurosis; Flat sheet-like tendon
- Connective tissue acts as a harness which allows muscle to transmit force & “pull” on a bone
- 500x the tensile strength of muscles, but unable to contract
What are muscle shapes ?
- Different arrangements relative to the axis of force generation
- Determines functional properties of the muscle
What are the 6 different shapes of muscle ?
- flat
- convergent
- pennate
- circular/sphincteral
- fusiform/parallel
- quadrate
What is a flat muscle?
- Parallel fibers with an aponeurosis
- i.e., Rectus abdominus
What is a convergent muscle?
- Arise from broad area to converge to form a single tendon
- i.e., Pectoralis major
What is a pennate muscle?
- Feather-like in the arrangement of the fascicles
- can be uni, bi, or multi axial
- i.e., quadriceps femoris
What is a circular/sphincteral muscle?
- Surround a body opening or orifice
- i.e., orbicularis oris
What is a fusiform/parallel muscle?
- Spindle shaped with round, thick belly & tapered ends
- i.e., biceps brachii
What is a quadrate muscle?
- four equal sides
- i.e., Rectus abdominus
What are levers?
- Muscles, the tendinous attachments & their relationship with the joints they cross result in 3 classes of levers (1, 2, 3)
What are the 3 variables that levers arrange in?
- F = force/energy
- A = axis/fulcrum
- R = resistance or load
What is a class 1 lever?
- FAR: I.e., Atlanta-occipital joint in the body (see-saw)
- Force/energy = posterior neck muscles
- Axis/fulcrum = cervical spine
- Resistance = weight of anterior skull
What is a class 2 lever?
- FRA: I.e., plantar flexion at the ankle joint in the body (wheelbarrow)
- Force/energy = calf muscles
- Resistance = body weight
- Axis/fulcrum = MTP joints
What is a class 3 lever?
- Most common levers in the human body; Gives an advantage to speed over strength
- AFR: I.e., elbow joint when lifting a book, tweezers, nail clippers
- Axis/fulcrum = elbow joint
- Force/energy = biceps muscle
- Resistance = weight resting in hand
What are the 4 types of muscular contraction ?
- isometric
- isotonic
- concentric
- eccentric
What is isometric/isotonic ?
- isometric = contraction with no movement; i.e., holding the weight at the top
- isotonic = contraction with movement; i.e., bicep curl
What is concentric/eccentric?
- 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
What is agonist/antagonist?
- agonist = the primary muscle creating a concentric movement
- antagonist = opposing muscle to the agonist, inactive while the agonist is contracting
What are fixators?
- Steadies proximal part of the limb throughout an isometric contraction while movement happens distally
- I.e., stabilize the scapulae during pushups
What are synergists ?
- Complements action of prime mover
How can you locate muscles ?
- The name of a muscle usually tells us something about its shape, action, location, or it is derived from a Latin root
What are the divisions of muscle groups?
- Biceps (2)
- Triceps (3)
- Quadriceps (4)
- “Ceps” = heads
What is the difference in muscle length/size?
- longus = long
- brevis = short
- Magnus = large
What are muscle attachment points?
- described in terms of its attachments to 2 bones & the action on the joints it crosses
What is origin/insertion?
- Origin = proximal attachment
- Insertion = distal attachment
What is a main action?
- the name of joint & its movement
