Muscle Anatomy Flashcards
What is the main function of muscles?
- Contraction
- Stabilising joints
- Maintaining continence of bladder and bowel
- Generating heat
What are the three classifications of muscle?
Skeletal, cardiac and visceral
What are the characteristics of skeletal muscle?
- Striated
- Voluntary contraction
- Somatic nervous system
What are the characteristics of cardiac muscle?
- Striated
- Involuntary contraction
- Autonomic nervous system
What are the characteristics of visceral muscle?
- Smooth
- Involuntary contraction
- Autonomic nervous system
What is muscle fiber called?
Myocytes
What are myofibers made up of?
Long cylindrical cells which are multi nucleated
What is in myofibrils?
Myofilaments
What are myofilaments?
Parallel protein chains of actin and myosin
What is the sarcomere?
Basic unit of muscle that contracts
What does thick myofilaments look like and what are they made up of?
They appear dark and contain mostly myosin
What does thin myofilaments look like and what are they made up of?
They appear light and contain actin
What gives the striated appearance of some muscle?
The actin and myosin myofilaments
What holds muscle fibres together?
They are held together by connective tissue
What is the belly of the muscle?
Area in the centre of the muscle rich in muscle fibres, blood vessels, and nerves
How are tendons formed?
Connective tissue sheets merge (bands of collagen) at each end and attach to bone
What are the 3 regions of the muscle?
Origin, belly and insertion
What is the origin of the muscle?
Portion of muscle attached to either the least moveable bone or most proximal bone
What is the insertion of the muscle?
Distal or most moveable attachment
What colour are tendons and why?
White as they only have few vessels
How fast do tendons heal?
Slowly
What is aponeuroses?
Sheet-like elastic tendon structures that cover a portion of the muscle belly
What protects tendons?
Sesamoid bones, fluid filled cushions or sheaths
What is the principle of muscle shortening?
Is a function of the length of fibres the longer the fibres the greater the shortening capacity
What is the principal of muscle power?
Is a function of cross-sectional area muscles which join tendons at an angle are stronger
What is a strap muscle?
Fibres that run longitudinally to the contraction direction
What is fusiform muscle?
Have a spindle-like shape, with parallel fibers that run the length of the muscle
What is pennate muscle?
The muscle fibres are arranged at an angle to the tendon, much like the bristles on a feather
What is bipennate muscle?
Feather-like architecture with muscle fibres that converge from two sides onto a central tendon
What is multipennate muscle?
Fibers are oriented at multiple angles along the force-generating axis.
What is the order of muscles from lowest to highest power?
Strap, fusiform, pennate, bipennate and multipennate
What is the order of muscles from longest to shortest shortening capacity?
Strap, fusiform, pennate, bipennate and multipennate
What are extrinsic muscles?
Muscles with attach the limb to the trunk
What are intrinsic muscles?
Muscles that are contained entirely within the limb
What are extensors?
Muscles that straighten bone alignment or open joint
What are flexors?
Muscles that angulate bones or bend joints
What is an agonist vs antagonist muscles?
A muscle that is an agonist for one movement will be an antagonist for the opposite
What are epaxial muscles?
Muscles dorsal to the line of the transverse process of vertebrea
What are hypaxial muscles?.
Ventral to transvere processes
