Functional Anatomy - Muscle Flashcards
Smooth Muscle
Internal, involuntary tissue.
Cardiac Muscle
Involuntary muscle found only in the wall of the heart.
Skeletal Muscle
External, voluntary muscle such as the deltoid or bicep.
Fusiform Muscle
- Fibres run parallel to each other and attach to a central tendon.
- Quicker, less powerful movements.
- Eg. Biceps brachii
Pennate Muscle
- Fibres approach the central tendon at on oblique angle.
- Large number of muscle fibres.
- Generate great force, but tire easily.
- Have three classifications:
- Unipennate
- Bipennate
- Multipennate
Unipennate
- Fibres are all on one side of the tendon.
- Enables great strength.
- Eg. Tibialis posterior in the calf.
Bipennate
- Muscle fibres attached to both sides of a centrally located tendon.
- Greater power, less range of motion.
- Eg. Rectus femoris in the quadriceps group and soleus.
Multipennate
- Multiple rows of fibres attached to a central tendon which branches into two or more tendons.
- Eg. Deltoid (anterior, posterior and lateral)
Angle of Pennation
- The angle of orientation between a tendon and muscle fibres.
- Varies from 0° to 30°
- As angle increases, the force transmitted is decreased.
Microstructure of Skeletal Muscle
- Epimysium > Perimysium > Endomysium > Muscle Fibre > Myofibril > Sarcomere > Actin & Myosin
Sliding Filament Theory
- Nerve impulse arrives at the neuromuscular junction and releases Acetylcholine.
- ACh causes depolarisation of motor end plate.
- Allows calcium to be released into the muscle.
- Calcium prompts reaction between myosin and actin.
- Breakdown of ATP releases energy which causes the myosin filaments cock.
- Results in contraction.
Isometric
- Muscle length remains unchanged while contracting.
- Joint angle remains the same.
Concentric
Muscle shortens while contracting.
Eccentric
Occurs when the muscle lengthens while still contracting.
Advantages of Isometric Training
- No equipment required
- Can be done anywhere
- Improves specific muscle strength quickly
- Develops static strength
Disadvantages of Isometric Training
- No joint movement
- Does nor contribute to cardiovascular fitness
- Lack of blood flow
- Not sufficient on its own
Plyometric Training
- Where a muscle is contracted eccentrically followed by a concentric concentration.
- Improves power and strength.
Advantages of Isotonic Training
- Strengthens the muscle throughout a range of movement
- Choose exercises to match the actions in your sport
- Can exercise all the major muscle groups
Disadvantages of Isotonic Training
- Forces are uneven throughout exercise
- Muscle groups are not fully strengthened.
- May result in muscle soreness because of the stresses during the eccentric contraction.
Isokinetic
- Where the muscle shortens at a constant speed.
- Only achieved through specialist equipment.
Advantages of Isokinetic Training
- Strengthens the entire muscle
- Exercises can be designed to mirror the actual speeds of sports-specific activities
- Fastest way to gain strength
Disadvantages of Isokinetic Training
- Can only be performed using specialised equipment
- Types of movements are limited.
Factors Affecting Muscle Force
- No. of fibres recruited
- Muscle fibre type
- Cross-sectional area
- Joint angle and muscle length
- Muscle shape and location
- Speed of contraction
- Type of muscle contraction
- Age
- Sex
Force-velocity
- High force = low velocity
- Low force = high velocity
- Max power is achieved at approx 1/3 max velocity.
Force-length
- Long/short length = Low force
- Resting length = high force (during contraction)
