Skeletal Muscle Flashcards
What are the two main types of muscle?
Striated and non-striated
What is the difference between the two different types of muscle?
In striated muscle, the arrangement of the myofibrillar apparatus produces a banding pattern.
What are the different types of striated muscle?
Skeletal and cardiac
What are the functions of skeletal muscle?
Movement, posture, joint stability and heat generation
What are the main groups in which skeletal muscle can be arranged?
Circular , parallel and pennate
hat are the most common arrangement of skeletal muscle?
Parallel
What are the three main categories of parallel muscle?
Strap, fusiform and fan shaped
Describe parallel muscles
Fibres run parallel to force generating axis
Describe strap muscles
Shaped like strap or belt. Fibres run longitudinally to contraction direction
Describe fusiform muscles
Wider and cylinderically shaped in the centre. Taper off at the end
Describe fan shaped muscle
Fibres converge at one end and spread over broad area at other end
Give an example for strap muscle
Sartorius
Give an example of fusiform muscle
Biceps brachii
Give an example of a fan shaped muscle
Pectoralis major
Describe circular muscles
Act as sphincters to adjust opening
Concentric fibres
What do circular muscle attach to?
Attach to skin, ligament and fascia rather than bone
Describe pennate muscle
One or more aponeurosis run through muscle body from tendon
What are the different types of pennate muscle?
Unipennate, bipennate, multipennate
Describe unipennate muscles
All fascicles on the same tendon
Describe bipennate muscles
Fascicles on both sides of central tendon
Describe multipennate muscles
Central tendon branches and fascicles run off each branch
Example of unipennate muscle
Extensor digitorum longus
Example of bipennate
Rectum femoris
Example of multipennate
Deltoid
What are ‘compartments’
Limbs divided into compartments delineated by fascia
What can trauma in one compartment cause?
Internal bleeding with exerts pressure on blood vessels and nerves. This can give rise to compartment syndrome
What is a muscle agonist?
Primer movers (main muscle responsible for a particular movement)
What is a muscle antagonist?
Oppose prime movers
What is a muscle synergist?
Assist primer movers (acting alone they can’t perform the movement but their angle of pull assist)
What are muscle neutralisers?
Prevent the unwanted actions that an agonist can perform
What are muscle fixators?
Act to hols a body part immobile whist another body part is moving
What are the two main types of contraction?
Isotonic contraction
Isometric contraction
What is isometric contraction?
Constant length, variable tension (muscle generates tension but is not shortening) eg hand grip
What’s isotonic contraction?
Constant tension, variable muscle length - the muscle changes length and moves the loa d
What are the different types of isotonic contraction?
Concentric and eccentric
What is concentric contraction?
Muscle shortens eg lifting load with the arm
What is eccentric contraction?
Muscle exerts a force while being extended eg walking downhill
What is a first class lever?
Effort at one end lost at other.
Extension and flexion of the head
What is a second class lever?
Effort at one end, fulcrum at other. Tip toes (plantar flexion of foot)
What is a third class lever?
Effort between load and fulcrum.
Flexion of elbow
What are the three main muscle fibre types?
Slow type I
Fast type II A
Fast type II X
What are the muscle fibre type based on?
Myosin heavy chain (MHC) expression
What are the two ways in which muscles are controlled in the body?
Size principle and rate code
What is muscle tone?
Healthy muscles never fully relaxed and retain amount of tension and stiffness (muscle tone)
What is the baseline muscles tone due to?
Motor neurone activity and muscle elasticity
What is hypotonia?
Lack of skeletal muscle tone
Symptom rather than condition
What is myotonia?
Inability to relax muscles at will
