Lecture 5 Flashcards
What are the 2 functions of muscle?
- mobility
2. stability
What does mobility help us to do?
Muscles generate movement enabling us to:
- react appropriately to external and internal stimuli
- transport materials within the body
What does stability help us to do?
Muscles help a joint maintain it’s integrity by:
- resist unwanted compression
- joint compression
What are the 3 class of muscle? Where are they found?
- Skeletal - striated and voluntary
- most places in the body - Smooth - striated and involuntary
- lines the gastrointestinal tract - Cardiac - non-striated and involuntary
- heart
Describe skeletal muscle
It is called skeletal muscle as it usually attaches to the skeleton via connective tissues. Helps cause movement.
Are about 40% of total body weight.
Has mobility and stability functions.
What are the characteristics of muscle?
- excitability (can be stimulated)
- contractibility (can generate tension / force)
- extensibility (stretch)
- elasticity
What is the organisation of the contractile elements?
- Whole muscle
- Fasciculus - a group of muscle fibres
- Muscel fibre/muscle cell
- Myofibril
- Myofilaments
- Actin and Myosin
What is the organisation of the non-contractile elements?
- Epimysium - surrounds the whole muscle
- Perimysium - surrounds fasciculi
- Endomysium - surrounds muscle fibre
All contain collagen and are considered connective tissues.
What are the functions of the connective tissue components of muscle?
- Mechanical coherence - holds all of the muscle parts together
- Independent movement of individual fibres and fasciculi
- Route for nerves and blood vessels
- transmission of forces to bone usually via a tendon
- Endomysium is also the site of metabolic exchange between muscle fibre and capillaries.
What are the 3 ways muscles attach to the bone?
- Via tendons
- Aponeurosis - broadsheet of connective tissues
- Muscle fibres may also directly attach to bone
What is an origin?
It is a proximal attachment (closer to the truck)
What is a insertion?
It is a distal attachment (usually moves towards the origin)
What are the 3 types of parallel muscle fibres
- flat and quadrilateral (e.g. thyrohyoid in the neck)
- Strap-like (e.g. sartorius)
- Fusiform - tapering at both ends (e.g. biceps brachi)
What are the 3 types of oblique fibres?
- triangular
- twisted / spiral orientation
- pennate - unipennate, bipennate, mulitpennate (feather like)
What types of muscle activations are there?
- Isometric = no movement (muscle stays at same length during contraction)
- Isotonic = constant force
- Concentric = muscle shortening during contraction
- Eccentric = muscle activates while being lengthened
