Types of Nerves

Nerves can be classified into four types based on their functionality. These are motor nerves, sensory nerves, autonomic nerves, and cranial nerves.

Motor Nerves

Motor nerves are responsible to send signals from the spinal cord and brain to all the muscles of the body.
The signals allow humans to perform activities such as talking, walking, drinking water, blinking eyes, sitting, etc.
Any injury to the motor nerve can lead to the weakening or shrinking of the muscles.

Sensory Nerves

The sensory nerves are responsible to generate signals in conflicting directions from another type of nerve known as motor nerves.
These nerves gather information such as pressure, pain, temperature, etc from the sensors that are located in the muscles, skin, and other internal organs which move it back to the brain and spinal cord.
Its injury causes numbness, pain, tingling, sensation, and hypersensitivity.

Autonomic Nerves

These nerves control the actions of the muscles of the heart.
The autonomic nerves manage the functions that are not under control, that is involuntary.

Cranial Nerves

There are 12 pairs of cranial nerves that appear from the lower side of the brain. Cranial nerves help to make facial expressions, movement of eye, and process smells. Hereunder, is the list of cranial nerves from front to back and their major functions:

Olfactory – a sense of smell
Optic – vision
Oculomotor – Eye movement; pupillary constriction and accommodation
Trochlear – Eye movements (intorsion, downward gaze)
Trigeminal – Somatic sensation from face, mouth, cornea
Abducens – Eye movements(abduction or lateral movement).
Facial – Controls the muscles of facial expression, etc.
Vestibulocochlear – Hearing, sense of balance
Glossopharyngeal – salivary gland
Vagus – muscles of the vocal cord.
Spinal accessory – shoulder and neck muscles
Hypoglossal nerves – the movement of the tongue.

Neural Tissue

All living organisms are made of cells. A unicellular organism has a single cell in its body, i.e., a single cell performs all basic life activities. However, in multicellular organisms, there are millions of cells. Most of these cells are specialized to carry out only a few functions efficiently. These functions are taken up by a distinct group of cells. Thus, it can be said that there is a division of labor in multicellular organisms.

A tissue is a group of cells that are similar in structure, origin, and function. The term ’tissue’ was given by Bichat. The branch of science dealing with the tissues is called ‘histology’. Mayer introduced the term histology. Malpighi is considered the “founder of histology. Broadly animal tissues are classified into four types: epithelial, connective, muscular, and neural.