These are the nerves which leave the brain and pass through various foramina and fissures in the skull.
There are total 12 pairs of cranial nerves and they are named as follow:
- 1st cranial nerve called Olfactory cranial nerve
- 2nd cranial nerve Called optic cranial nerve.
- 3rd cranial nerve called oculomotor nerve.
- 4th Cranial nerve called trochlear nerve.
- 5th cranial nerves called Trigeminal
- 6th cranial nerve called Abducent
- 7th cranial nerve called Facial nerve.
- 8th cranial nerve called Vestibulocochlear nerv1.
- 9th cranial nerve called Glossopharyngeal nerve.
- 10th cranial nerve called vagus nerve.
- 11th cranial nerve accessory nerve.
- 12th cranial nerve called Hypoglossal nerve
Mnemonics for memorization of cranial nerves :
The mnemonics for memorization of cranial nerves is ” On old Olympus towering top a Forest and Georgian viewed a horse ”
- On Olfactory cranial nerve
- Old optic cranial nerve.
- Olympus oculomotor nerve.
- towering trochlear nerve.
- top Trigeminal
- A Abducent
- Forest Facial nerve.
- And Auditory nerve also called Vestibulocochlear nerve
- Georgian Glossopharyngeal nerve.
- Viewed vagus nerve.
- a Accessory nerve.
- Horse Hypoglossal nerve
Classification of Cranial Nerves:
Cranial Neves may be :
Motor that is they carry information towards the central nervous system that is brain and spinal cord.
Mixed that is that have both sensory and motor nerve fibers.
Sensory nerves of the cranial nerves:
Among cranial nerves, 3 cranial nerves are entirely sensory that is …
- olfactory cranial nerve
- optic cranial nerve
- vestibulocochlear cranial nerve
So for memorization one 28 (one 28 motorcycles), cranial nerves are sensory.
Motor cranial nerves of cranial nerves :
There are 05 cranial nerves which are entirely motor that is they carry information towards central nervous system.
These are :
- Oculomotor cranial nerve
- Trochlear cranial nerve
- Abducent cranial nerve
- Accessory cranial nerve
- Hypoglossal cranial nerve.
For memorization cranial nerve 346 11 12 (three , four , six , one one , one two ) are motor .
Mixed nerves of the cranial nerves :
These are the nerves which act as both sensory and motor these are
- Trigeminal cranial nerve
- Facial cranial nerve
- Glassopharygeal cranial nerve
- Vagus cranial nerve
For memorization cranial nerves 5,7, 9 and 10 are mixed.
Each nerve exits through opening in the skull and has a specific function the specific opening and function of each cranial nerve is given below.
1. Olfactory nerve :
Olfactory cranial nerve exit through the opening in the cuneiform plate of ethmoid and it’s function is the smell .
2. Optic nerve :
Optic nerve exits from the skull via optic canal and its function is control of the vision.
3. Oculomotor cranial nerve :
Oculomotor cranial nerve exit from the skull via superior orbital fissure and it’s function is to raise upper eyelid , turns eyeball upward, downward and medially, constrict pupil and accommodates eye.
4. Trochlear cranial nerve :
Trochlear nerve exits via superior orbital fissure and it assists in turning eyeball downward and laterally.
5. Trigeminal nerve :
The trigeminal nerve has three division
These are ophthalmic division, maxillary division, mandibular division.
Ophthalmic division of trigeminal nerve :
it exits via superior orbital fissure and it supply cornea, scalp, eyelids, the skin of forehead and nose, also mucous membrane of Paranasal sinuses and nasal cavity.
Maxillary division of trigeminal nerve :
it exits from the skull via foramen rotundum and it supply skin of face over maxilla, teeth of the upper jaw, mucous membrane of the nose the plate and maxillary sinus.
Mandibular division of trugeminal nerve :
it exits for the skull via foramen ovale and it supply muscle of mastication, mylohyoid, anterior belly of digastric, tensor vile palatini and tensor tympani.
The mandibular division also has the sensory supply to the skin of the cheek, skin over mandible and side of the head, teeth of the lower jaw and temporomandibular joint , mucous membrane of the mouth and anterior part of the tongue .
Abducent nerve :
It exits from the skull via superior orbital fissure and its motor supply is to lateral rectus muscle which turns eyeball laterally.
Facial nerve :
Facial nerve exits from the skull via internal acoustic meatus, facial canal and then via stylomastoid foramen. its motor supply is to muscles of face and scalp, posterior belly of digastric, stapedius muscle and stylohyoid muscle.
Its sensory function is taste from anterior two third of the tongue , the floor of the mouth and palate.
Vestibulocochlear nerve :
it has two division that is vestibular and cochlear. The vestibular division exists from the skull via internal acoustic meatus and takes sensory fibers from utricle, saccule, semicircular canal it controls position and movement of the head.
The cochlear division function is the sensory supply of the organ of Corti.
Glossopharyngeal nerve :
This nerve exits from the skull via jugular foramen. It has a motor, sensory and secretomotor fibers.
Motor supply is to stylopharyngeus muscle, which assists in swallowing.
Sensory function is general sensation and taste from posterior one-third of tongue and pharynx, carotid sinus and carotid body.
Secretomotor parasympathetic supply parotid salivary gland.
Vagus nerve :
Vagus cranial nerve exits the skull via jugular foramen and it supplies the heart, greater thoracic blood vessels, larynx, trachea, bronchi and lungs, the alimentary tract from the pharynx to splenic flexure of colon, kidney, pancreas, and liver.
Accessory Nerve :
Accessory nerve has cranial and spinal roots both leave the skull via the jugular foramen
Cranial root has the motor supply to muscles of the soft palate ( except tensor veli palatini).
Pharynx (except stylopharyngeus) and larynx (except cricothyroid ).
Spinal root has the motor supply to sternocleidomastoid and trapezius muscle.
Hypoglossal cranial nerve :
Hypoglossal cranial nerve exit from the skull via Hypoglossal canal and it has a motor supply to the muscle of the tongue (except palatoglossus) and it controls shape and movement of the tongue.
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