Functional Anatomy Flashcards
Muscle types
Cardiac:
- only found in the heart
- involuntary
Smooth:
- found in the diaphragm and in walls of blood vessels and intestines
- involuntary
Skeletal:
- muscle adjoining to skeletal bones and tendons
- voluntary
- Comes in two types:
- Fusiform: - fibres run parallel to each other and produces quick but less powerful force
- Penniform: - fibres run at an oblique angle and produce great force but tire easily
- classified further into the way they branch from the tendon:
- Unipennate: fibres are all on one side of the tendon enabling great strength
- Bipennate: fibres are attached to both sides of the central tendon making them look like a feather. Great power but less range of motion
- Mulitpennate: multiple rows of fibres attached to a central tendon which branch into two or more tendons
- classified further into the way they branch from the tendon:
Muscle fibre type: Slow twitch / type 1
- Red in colour
- slow contraction speed
- Aerobic energy source
- low in glycogen
- high in capillary blood flow
- Best suited to endurance events
Eg. Marathon should
Muscle fibre type: Fast twitch / type 2a
- white in colour
- recruited during high intensity work
- medium fibre diameter
- high in glycogen stores
- medium amount of oxidative enzymes
- medium ability to generate ATP
- large neuronal size
- medium speed of contraction
- medium force of contraction
- medium resistance to fatigue
- medium aerobic capacity
- high anaerobic capacity
- suited for sprinting
Eg. 200m
Muscle fibre type: Fast twitch / type 2b
- white in colour
- tires quickly
- contract quickly and powerfully
- large fibre diameter
- low myoglobin content
- high glycogen stores
- low oxidative enzymes
- large motor neuron size
- suited for anaerobic work
Eg. 100m
Muscle structure: Tendons
- connective tissue adjoining muscles and bones
Muscle structure: Epimysium
- thin connective casing of the muscle
- outside layer
Muscle structure: fascicle
- bundles of muscle fibres inside epimysium
Muscle structure: endomysium
- connective tissue surrounding each muscle fibre
Muscle structure: muscle fibre
- made up of hundreds of myofibril
Muscle structure: sarcolemma
- thin casing of each muscle fibre
Muscle structure: myofibril
- comprises each muscle fibre
Muscle structure: sarcomere
- basic contractile unit of the muscle
Made up of:
Myosin - thick myofilament (red)
Actin - thin myofilament (blue)
Z-line - boundary between one sarcomere and the next
I band - region between adjacent A bands, both end of the sarcomere
A band - consists of thick and thin filaments, where contraction happens
H Zone - contains only myosin filament, middle of sarcomere
Sliding filament theory
- Nerve impulse arrives at the neuromuscular junction
- acetylcholine is released (ACH)
- presence of ACH causes depolarisation of the motor end plate
- allows calcium to be released in to the middle
- reaction between the myosin and the actin in each muscle fibre
- this will only occur if there is sufficient calcium ions and ATP stores
- Break down of ATP releases energy
- Enables myosin filaments to cock like oars and form cross bridges between myosin and actin
- Occurs in all sarcomere at the same time, they all shorten which is how the entire muscle appears to shorten
- When fully contracted the filaments almost completely overlap causing the I band and the H zone to disappear
- although the sarcomere changes length, the actin and myosin don’t change, they just overlap
Types of muscle action: Isometric
- does not change length of muscle
- joint angle also remains the same
Adv: - no equipment required and can be done anywhere
Types of muscle action: Isotonic
- length of muscle does change
- Classified in two types:
- concentric: - muscle shortens while it develops tension and the angle of one or more joints changes
- eccentric - muscle lengthens as it develops tension
Types of muscle action: Isokinetic
- muscle shortens as a constant speed
- only achieved using special equipment
- strengthens entire muscle
Force - Velocity
- the force a muscle can create will decrease with the increasing velocity of shortening
- the force a muscle can resist increases when the velocity is increased
- greatest amount of force can be developed during an isometric contraction
- power is maximised when there is a combination of strength and speed or force and velocity
Force - length
- the length and angle at a joint impact how much force can be generated
- longer muscles can create greater range of motion at a joint
- shorter muscles produce greater amounts of force
The nervous system
- comprises the brain, spinal cord, nerves and the sensory receptors Purposes: - receive information - process information - carry out response
Motor neuron and sensory neurons
- conduct impulses from the brain to the muscles
- conduct impulses from the sensory organs or receptors to the brain (eg. Pain)
Motor unit
- refers to a single motor neuron and all its associated muscle fibres
- can comprise of 4 to 1000 associated muscle fibres
- small units create fine movement
- large units are recruited for strength
Neuromuscular responses to training
- with strength training the first improvements are at the neuromuscular level
- improved technique
- recruitment of more motor units
- increased firing rate of motor units
- firing pattern of motor units are better recruited
All or nothing principal
- muscle fibres in a motor unit will only contract if a certain number of impulses is reached
- when this happens they all contract at once with the same force and at the same time
- like turning a light switch on or off, there is no in between
Muscle innervation process
- message is sent from the brain, leaving as an action potential
- dendrites receive signals from the CNS and sends them to the cell body (soma)
- axon extends from the axon hillock and sends messages to other cells (away from cell body)
- Neucleus is the middle brain of the neuron
- myelin and axon form the middle tube on a diagram
Bipolar: - one axon and one dendrite (found in nasal cavity)
Multipolar: - one axon and many dendrites (brain, spinal cord)
Unipolar: - single extension from soma, carry signals to spinal cord
Anaxonic: - many dendrites but no axons (found in retina)
Muscle structure: perimysium
- connective tissue surrounding the fascicle
