Lecture 7: Muscle Tissue Overview Flashcards
Compare and contrast the 3 basic types of muscle tissue
- Skeletal muscle tissue: attach to bones and skin, striated, voluntary
- Cardiac muscle tissue: only in heart, striated, involuntary
- Smooth muscle tissue: in the walls of hollow organs eg stomach, urinary bladder, and airways
- not striated
- involuntary
List the 4 special characteristics of muscle tissue
- Excitability: ability to receive and respond to stimuli
- Contractility: ability to shorten when stimulated
- Extensibility: ability to be stretched
- Elasticity: ability to recoil to resting length
What are the 4 functions of muscle
- Heat generation (especially skeletal muscle)
- Stabilizing joints
- Maintains posture and body position
- Movement of bones or fluids
What are the 3 different types of connective tissue found in the skeletal muscle?
- Epimysium: dense regular connective tissue surrounding entires
Muscle - Perimysium: fibrous connective tissue surrounding fascicles (groups of muscle fibers)
- Endomysium: fine areolar connective tissue surrounding each
muscle fibre
Refer to slide 8
Contraction doesn’t always shorten a muscle. What’s the difference between isometric and isotonic?
Isometric contraction: no shortening, muscle tension increases but does not exceed the load
Isotonic contraction: muscle shortens because muscle tension exceeds the load
What is muscle tone
Constant, slightly contracted state of all muscles
- due to spinal reflexes that activate groups of motor units alternately in response to input from stretch receptors
- keeps muscles firm healthy and ready to respond
Isotonic contractions are either concentric or eccentric. What’s the difference?
Concentric contractions: the muscle shortens and does work
Eccentric contractions: the muscle contracts as it lengthens
What is an isometric contraction?
The load is greater than the tension the muscle is able to develop
-tention increases to the muscles capacity, but the muscle neither shortens or lengthens
Muscle fibre type is classified according to two characteristics: speed of contraction: slow or fast
Slow fibres: red- postural muscles
Fast fibres: white- fingers
Smooth muscles usually have two layers. What are they?
What kind of nerve fibres inner ate smooth muscle
Longitudinal and circular
Innervated by autonomic nerve fibres
What are the 4 functional groups of skeletal muscles?
- Prime movers: provide the major force for producing a specific movement
- Antagonists: opposes or reverses a particular movement
- Synergists: add force to a movement, and reduces undesirable or unnecessary movement
- Fixators: Synergists that immobilize a bone of muscles origin
Naming skeletal muscles. What are the 7 methods used in naming skeletal muscles?
- Location
- Shape eg deltoid (triangle)
- Relative size eg Maximus, minimus, longus (long)
- Direction of fibres or fascicles eg rectus (fibres run straight), transverse, and oblique
- Number of origins eg biceps (2 origins) and triceps (3 origins)
- Location or attachments: name according to point of origin or insertion
- Action eg flexor or extensor
What are the 5 different arrangement of fascicles
- Circular: fascicles arranged in concentric rings (eg orbicularis oris)
- Convergent (fascicles converge towards a single tendon insertion eg pectoralis major
- Parallel: fascicles parallel to the long axis of a strap like muscle eg sartorius
- Fusiform: spindle shaped muscle with parallel fibres eg biceps brachii
- Pennate: short fascicles attach obliquely to a central tendon running the length of the muscle eg rectus femoris
Name the muscles of facial expression
Epicranius: it’s a bipartite muscle consisting of the frontalis, occipitalis, and galea aponerotica which is a cranial aponeurosis connecting the above two muscles. The two muscles have alternate actions of pulling the scalp forward and backward
Muscles of mastication and tongue movement:
There are 4 pairs involved in mastication:
1. Prime movers of jaw closure: temporalis and masseter
2. Grinding movements: medial and lateral pterygoids
All are innervated by cranial nerve 5: trigeminal nerve
