Topic 32 - Muscular Tissue : Skeletal Muscle

Question 1

Length of the skeletal myofibres?

Answer 1

10-120mm

Question 2

origin…?

Answer 2

by fusion of mononuclear myoblast cells

Question 3

Function?

Answer 3

-Non-branching multinucleated fibres. Quick contraction with high fatigue. Impulses generated by motor endplate. Found in locomotor organs (muscles).

Question 4

Morphology?

Answer 4

• Longitudinal: elongated nuclei (subsarcolemmal), traverse striations.
• Cross-section: polygonal cells, no cross-striations

Question 5

Organization?

Answer 5

• Myofibrils are surrounded by endomysium (fine reticular CT).
• Primary bundles/fascicles are covered by perimysium (dense collage fibres).
• Muscle is ensheathed by epimysium (thick and dense collagen CT).

Question 6

How is the muscle fibres innervated?

Answer 6

-by stretch receptors (with sensory capsule) and gamma motor neurons (motor neuron endplates attached to each muscle fibre).

Question 7

What is neuromuscular junction?

Answer 7

myelinated nerve fibre and axon terminal. Motor neuron endplate contains acetyl-choline vesicles. Acetyl-choline receptors are contained in the sarcolemma of the muscle fibre.