ANATOMY - Muscle Flashcards
What is skeletal muscle composed of?
Mainly muscle tissue
Also
- connective tissue
- blood vessels
- nerves
What is the cell membrane of a muscle cell called?
Sarcolemma
What binds muscle fibres together?
Connective tissue sheaths
What is the name of the layer which surrounds the entire muscle?
Epimysium
What is the name of the layer which surrounds each fascicle of muscle fibres?
Perimysium
What is the name of the layer which surrounds each individual muscle fiber?
Endomysium
What is a fascicle?
Group of muscle fibres
What separates muscles groups?
Fascia
Is the origin or insertion of a muscle more moveable?
The insertion
What are the two types of muscle attachments ?
- Fleshy attachments
- Indirect attachments
Describe a fleshy muscle attachment
The connective tissue fibres which join muscle to bone are SHORT
Describe an indirect attachment of a muscle to bone?
The connective tissue fibres form a tendon or an aponeurosis
What does the organisation of muscle fibres affect?
- power of contraction
- range of contraction
Are fibres in a fascicle parallel to each other?
Yes
How can the arrangements of fascicles vary?
- parallel
- circular
- pennate
- convergent
Describe arrangement of fascicles in parallel muscles.
The fascicles run parallel to the long axis of the muscle
What happens when a parallel muscle contracts?
The muscle gets shorter and the diameter of the muscle body increases
What are the two types of parallel muscles?
Strap like eg SCM
Fusiform eg biceps brachii (thicker in centre than ends)
Describe arrangement of a convergent muscle
The origin is broad and the fascicles converge towards the insertion
Give example of convergent muscle
Pec major
Describe pennate muscle structure
- Large amount of short fibres in a small space
- can have 1 or more tendons
- the fascicles are oblique to the tendon
What are the three types of pennate muscle?
- unipennatee
- bipennate
- multi pennate
Describe unipennate muscle
Fibres insert into one side of tendon
Describe bipennate muscle
Fibres attach to both sides of tendon
Describe multipennate muscle
Fascicels insert onto one large tendon from all sides e.g recuts femoris
Describe the structure of a circular muscle
What happens when a circular muscle contracts
The cavity closes
Give example of a circular muscle
Sphincters e.g orbicularis oris
How can muscle bellies be organised
- 1 belly with tendon at either end
- 2 bellies which attach to a single tendon at one end
- many heads in series e.g digastric muscle
What are tendons made of?
Collagen fibres surrounded by connective tissue
Are tnedons innervated ?
Yes but only with sensory nerves.
What is a sesamoid bone?
A bone located within a tendon
What is a sesamoid fibrocartilage?
Cartilage in a tendon
What is a bursa?
A sac containing synovial fluid
What is the function of a bursa?
Distribute pressure and prevent friction
What can happen if you have an infected bursa?/
Swelling
What is a synovial sheath?
A sac containing synovial fluid which surrounds a tendon e.g synovial sheaths surrounding tendons in fingers
Function of synovial sheath?
Protect against friction
What can happen if a synovial sheath becomes infected?
There can be damage to the tendon which can immobilise the limb
What is a prime mover/agonist
The main muscle for a movement
What is an antagonistic muscle
Opposes / reverses a movement
What is a synergist?
Helps the prime mover by ;
- adding extra force
- reducing undesirable movement
What is a fixator?
A type of synergist which holds a bone firmly in place
What is a motor unit?
A somatic motor nerve and all the muscle fibres innervated by it
