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The Nerve Tissue & The Nervous System

The Nerve Tissue & The Nervous System

The Nerve Ending

The nerve end in organs by specialized modified structure called nerve endings. Some of endings sensory receptor as (dendrites) & another motor or effector (axon).

The classification of endings according to the tissue found in it.

1.    Striated muscle:

A- Neuromuscular spindle are stretch receptor organs within skeletal muscle which are responsible for regulation of muscle tone by the spinal stretch reflex.

It is encapsulated, fusiform structure each spindle contain 3-10 modified skeletal muscle fibers surrounded by connective tissue, enter nerve in one side & branches to surrounding of muscle fibers as spiral form.

B- Motor end plate: The motor nerve fiber branches to supply numerous striated muscle fibers when the nerve is near to the muscular fiber it branches as bird feet & the terminal nerve fiber enlarge to form motor end plate.

2.     Epithelial tissue:

Sensory endings, the nerve fiber branches in skin between the epithelial cells specially in deep layer of epidermis, the branches end as bulbs.

Some of branches end comprise as lamellar network each branch of lamellar network as company one epithelial cell and is called disk of Merkel & this is usually found in hair follicle & hard palate.

3.    Connective tissue:

A- Free nerve endings: they are the simplest form of sensory receptor, consisting of numerous small terminal branches of afferent nerve fiber found in serous, mucous membrane, sclera.

B- Encapsulated nerve ending.

o       Meissner corpuscles:

Found in dermis of skin, particularly in fingertip, sole of feet, nipple, eyelids, lips & genitalia.

The receptor consist of delicate collagenous tissue capsule surrounding a mass of plump, consist of flattened tactile epithelial cells embedded in fibrous connective tissue the nerve fibers coiled spirally the tactile cell.