Cranial Nerves
What are the 12 cranial nerves and functions?
The cranial nerves are those that hook up with the brain. In people, they’re made up of 12 pairs that begin from the brain and join it to the sensory organs and muscle mass.
In the meantime, spinal nerves join the spinal cord to sensory cells and numerous muscle mass all through the body. There are 31 pairs of those nerves.
The cranial nerves carry out sensory and motor functions. The function is set in line with the structures innervated by every pair. The 12 pairs of cranial nerves are numbered in Roman numerals in craniocaudal sequence.
Be taught more in regards to the Brain .
| Definition | A set of 12 peripheral nerves emerging from the brain that innervate the structures of the head, neck, thorax, and abdomen. |
| Nerves | Olfactory (smell) nerve (CN I), optic nerve (CN II), oculomotor nerve (CN III), trochlear nerve (CN IV), trigeminal nerve (CN V), abducens nerve (CN VI), facial nerve (CN VII), vestibulocochlear nerve (CN VIII), glossopharyngeal nerve (CN IX), vagus nerve (CN X), accessory nerve (CN XI), and hypoglossal nerve (CN XII). Mnemonic : – The Golden Object Had Cobwebs Making the Broom Spin Sweeping the Creepy Closet |
| Types of nerves | – Sensory: olfactory (smell) nerve (CN I), optic nerve (CN II), vestibulocochlear nerve (CN VIII) – Motor: oculomotor nerve (CN III), trochlear nerve (CN IV), abducens nerve (CN VI), accessory nerve (CN XI), hypoglossal nerve (CN XII). – Mixed (both): trigeminal nerve (CN V), facial nerve (CN VII), glossopharyngeal nerve (CN IX), vagus nerve (CN X). Mnemonic (in numerical order) : Samantha Left the Market Wet at Two in the Morning Saying: “Dream Wishing for the Cursed Dawn” |
What are the 12 cranial nerves and functions?
- Olfactory (smelling) nerve (CN I) – sensory
- Optic nerve (CN II) – sensory
- Oculomotor nerve (CN III) – motor
- Trochlear nerve (CN IV) – motor
- Trigeminal nerve (CN V) – combined
- Abducens nerve (CN VI) – motor
- Facial nerve (CN VII) – combined
- Vestibulocochlear nerve (CN VIII) – sensory
- Glossopharyngeal nerve (CN IX) – combined
- Vagus nerve (CN X) – combined
- Accessory (spinal) nerve (CN XI) – motor
- Hypoglossal nerve (CN XII) – motor
I- Olfactory nerves
They originate within the olfactory area of every nasal cavity, cross the ethmoid bone and end within the olfactory bulb.
They’ve an exclusively delicate perform, being responsible for conducting olfactory impulses.
| Type | ASE/AVE |
| Core | None |
| Innervation field | Sensory: Nasal mucosa |
II- Optic nerves
They’re composed of a thick bundle of nerve fibers originating within the retina area that penetrate the skull by means of the optic canal.
They’ve a strictly delicate function.
| Type | ASE |
| Core | None |
| Innervation field | Sensory : Retina |
III- Oculomotor nerve
It’s a motor nerve, responsible for eye movement.
| Type | ESG, EVG (parasympathetic) |
| Cores | Oculomotor nerve nucleus (ESG) Accessory oculomotor nerve nuclei (EVG) |
| Innervation field | Motor : all extraocular muscles except lateral rectus and superior oblique (ESG); ciliary muscle, sphincter pupillae muscle (EVG) |
IV- Trochlear nerve
It’s a nerve with a sensitive and motor half, additionally associated to eye movement and vision.
| Type | ESG |
| Core | Trochlear nerve nucleus |
| Innervation field | Motor : superior oblique muscle |
V- Trigeminal nerve
It has a motor portion and a sensory portion.
The motor portion acts on the muscle mass associated to chewing.
The sensory portion has three branches: the ophthalmic, maxillary and mandibular. It’s responsible for the innervation of the face, a part of the scalp and the innermost areas of the skull.
| Type | EVE, ASG |
| Cores | Motor nucleus of the trigeminal nerve (SVM) Main sensory nucleus of the trigeminal nerve (SSG) Spinal nucleus of the trigeminal nerve (SSG) Mesencephalic nucleus of the trigeminal nerve (SSG) |
| Divisions | Ophthalmic nerve (CN V1) Maxillary nerve (CN V2) Mandibular nerve (CN V3) |
| Innervation field | Motor : muscles of mastication, mylohyoid, anterior belly of digastric , tensor tympani muscle (EVE) Sensory : Scalp, face, orbit, paranasal sinuses, anterior two-thirds of tongue (ASG) |
VI- Abducens nerve
It’s responsible for the innervation of the lateral rectus muscle of the eye.
| Type | ESG |
| Core | Abducens nerve nucleus |
| Innervation field | Motor : lateral rectus muscle |
VII- Facial nerve
It’s a mixed nerve, with a motor and a sensory portion. The motor portion is represented by the facial nerve itself, associated to facial expressions, saliva secretion and tear production.
The facial nerve gives motor innervation to all of the cutaneous muscle mass of the head and neck.
The sensory portion known as the intermediate nerve and acts on muscular and taste sensitivity.
| Type | EVG (parasympathetic), EVE, AVG, AVE, ASG |
| Cores | Superior salivatory nucleus (SVG) Motor nucleus of the facial nerve (SVE) Nuclei of the solitary tract (AVG, AVE) Spinal nucleus of the trigeminal nerve (ASG) |
| Innervation field | Sensory : middle ear, nasal cavity, soft palate (AVG); anterior two-thirds of the tongue (AVE); external acoustic meatus (ASG) Motor : lacrimal, submandibular, sublingual, basal, palatine glands (EVG); facial mimic muscles (EVE) |
VIII- Vestibulocochlear nerve
It’s an exclusively delicate nerve. In reference to its name, it has a vestibular and cochlear part.
The vestibular part is related to stability. The cochlear part is expounded to listening to.
| Type | ASE |
| Cores | Vestibular nuclei Dorsal and ventral cochlear nuclei |
| Innervation field | Sensory : spiral organ (of Corti), macula of the utricle, macula of the saccule, ampullae of the semicircular canals (ESA) |
IX- Glossopharyngeal nerve
It’s a nerve with sensory and motor functions. It’s responsible for the sensitivity of a part of the tongue, pharynx and auditory tube. The motor part is related to the muscle mass of the pharynx.
| Type | EVE, EVG (parasympathetic), AVE, AVG, ASG |
| Cores | Nucleus ambiguus (EVE, AVG) Inferior salivatory nucleus (EVG) Nucleus of the solitary tract (AVE, AVG) Spinal nucleus of the trigeminal nerve (ASG) |
| Innervation field | Motor : stylopharyngeus and pharyngeal constrictors (EVE); parotid gland (EVG) Sensory : posterior third of tongue (AVE), middle ear, pharynx, epiglottis (AVG); posterior third of tongue, soft palate (ASG) |
X- Vagus nerve
It’s a nerve with motor and sensory functions. It innervates nearly all organs under the neck, with parasympathetic innervation. It’s responsible for sustaining important functions corresponding to regulating coronary heart rate.
| Type | EVG (parasympathetic), EVE, AVE, AVG, ASG |
| Cores | Posterior nucleus of the vagus nerve (dorsal motor nucleus) (EVG) Nucleus ambiguus (EVE) Nuclei of the solitary tract (AVE, AVG) Spinal nucleus of the trigeminal nerve (ASG) |
| Innervation field | Motor : thoracic and abdominal viscera (EVG); laryngeal and pharyngeal muscles (EVE) Sensory : epiglottis (AVE); thoracic and abdominal viscera, carotid body (AVG); external auditory canal, retroauricular skin, posterior part of meninges (ASG) |
XI- Accessory nerve
It’s an basically motor nerve, performing in functions associated to swallowing and head and neck movements.
| Type | ESG/EVE* |
| Cores | Nucleus ambiguus Accessory nerve nuclei (C1-C5) |
| Innervation field | Motor : laryngeal muscles, sternocleidomastoid, trapezius |
XII- Hypoglossal nerve
It’s an exclusively motor nerve. It emerges from the skull by means of the hypoglossal canal and goes to the intrinsic and extrinsic muscle mass of the tongue. It’s associated to the movement of the tongue.
| Type | ESG |
| Core | Hypoglossal nerve nucleus |
| Innervation field | Motor : intrinsic muscles of the tongue, extrinsic muscles of the tongue (except the palatoglossus) |
To gain more information, see additionally:
- Nerves of the Human Body
- Nervous System
- Exercises on the Nervous System