There are total 12 pairs of cranial nerves that originate from our brain and brain stem. Each of them carries different functions related to different senses of body. Apart from sensory functions there are also some that work as motor nerves or mixed nerves.
The cranial nerves are;
- cranial nerve one - Olfactory nerve
- cranial nerve two - Optic nerve
- cranial nerve three - Occulomoter nerve
- cranial nerve four -Trochlear nerve
- cranial nerve five - Trigeminal nerve
- cranial nerve six - Abducent nerve
- cranial nerve seven - Facial nerve
- cranial nerve eight - Vestibulocohlear nerve
- cranial nerve nine - Glossopharyngeal nerve
- cranial nerve ten - Vagus nerve
- cranial nerve eleven - spinal accessory nerve
- cranial nerve twelve - Hypoglossal nerve
-This nerves supply different section or part of the body
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| Diagram showing the situation of the cranial nerves in the brain and brain stem. |
-The functions of each of the cranial nerves is explained below:
1. Olfactory (CN I)
This is a type of sensory nerve that contributes in the sense of smell in human being. These basically provide the specific cells that are termed as olfactory epithelium. It carries the information from nasal epithelium to the olfactory center in brain.
2. Optic nerve (CN II)
This again is a type of sensory nerve that transforms information about vision to the brain. To be specific this supplies information to the retina in the form of ganglion cells.
3. Oculomoter nerve (CN III)
This is a form of motor nerve that supplies to different centers along midbrain. Its functions include superiorly uplifting eyelid, superiorly rotating eyeball, construction of pupil on the exposure to light and operating several eye muscles.
4. Trochlear nerve (CN IV)
This motor nerve also supplies to the midbrain and performs the function of handling the eye muscles and turning the eye.
5. Trigeminal nerve (CN V)
This is a type of largest cranial nerve in all and performs many sensory functions related to nose, eyes, tongue and teeth. It basically is further divided in three branches that are ophthalmic, maxillary and mandibular nerve. This is a type of mixed nerve that performs sensory and motor functions in brain.
6. Abducent nerve (CN VI)
This is again a type of motor nerve that supplies to the pons and perform function of turning eye laterally.
7. Facial nerve (CN VII)
This motor nerve is responsible for different types of facial expressions. This also performs some functions of sensory nerve by supplying information about touch on face and senses of tongue in mouth. It is basically present over brain stem.
8. Vestibulocochlear nerve (CN VIII)
This motor nerve is basically functional in providing information related to balance of head and sense of sound or hearing. It carries vestibular as well as cochlear information to the brain and is placed near inner ear.
9. Glossopharyngeal nerve (CN IX)
This is a sensory nerve which carries sensory information from pharynx (initial portion of throat) and some portion of tongue and palate. The information sent is about temperature, pressure and other related facts.
It also covers some portion of taste buds and salivary glands. The nerve also carries some motor functions such as helping in swallowing food.
10. Vagus nerve (CN X)
This is also a type of mixed nerve that carries both motor and sensory functions. This basically deals with the area of pharynx, larynx, esophagus, trachea, bronchi, some portion of heart and palate. It works by constricting muscles of the above areas. In sensory part, it contributes in the tasting ability of the human being.
11. Spinal accessory nerve (CN XI)
As the name intimates this motor nerve supplies information about spinal cord, trapezius and other surrounding muscles. It also provides muscle movement of the shoulders and surrounding neck.
12. Hypoglossal nerve (CN XII)
This is a typical motor nerve that deals with the muscles of tongue.
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