Page 99 - Headlines Histology2024_Neat

• Information from muscle spindle is subconscious and is important for
regulating muscle tone, adjusting posture and controlling movements.

Motor nerve endings

Neuromuscular junction

• A neuromuscular junction is made up of: motor-end plate, synaptic cleft and
postsynaptic sole plate.

Motor-end plate

• It is formed of terminal branches of the motor axon that loose its myelin
sheath and divides to form several small bulbous swellings called motor end
plate.

• Each end plate occupies a trough in the muscle cell surface (sole plate) and
is covered by extension of the Schwann cell cytoplasm.

• The end plate cytoplasm is rich in rER, mitochondria and clear synaptic
vesicles containing acetylcholine.

Synaptic cleft

• It is a wide gap, about 30 ?m separating the end-plate from the sole plate.
Sole plate

• It is the portion of sarcolemma that comes in contact with the end-plate.
• It has many invaginations (troughs) that fit each end plate.
• Each trough has several transverse enfolding called junctional folds to

increase the surface area of sarcolemma. Underneath the sarcolemma, the
sarcoplasm is rich in mitochondria and aggregated nuclei.

CENTRAL NERVOUS SYSTEM

• The central nervous system comprises the brain and spinal cord.
• Within the CNS, internal and external stimuli are analyzed and integrated to

produce appropriate responses in various effector organs.
• On gross examination, the CNS is made up of gray matter and white matter.

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