Introduction to the cranial nerves

3,292views

00:00 / 00:00

Notes

Introduction to the Cranial Nerves

Figure 1. Ventral surface of the brain showing the origins of the cranial nerves.
Figure 2. Lateral view of fifth week embryo, showing innervation of the pharyngeal arches.  




Cranial NerveSensory or motor? Components
Main Function / Distribution
Olfactory nerve (CN I)
Sensory
Special Sensory
Smell
Optic nerve (CN II)
Sensory
Special Sensory
Vision
Oculomotor nerve (CN III)
Motor
Somatic Motor
Extraocular muscles (except superior oblique & lateral rectus)

Visceral Motor (Parasympathetic)


Ciliary muscle & sphincter pupillae muscle

Trochlear nerve (CN IV)
Motor
Somatic Motor
Superior oblique
Trigeminal nerve (CN V)
Both
Somatic (Branchial) Motor
Muscles of mastication
Somatic Sensory
Sensory innervation of face, scalp and mouth
Abducens nerve (CN VI)
Motor
Somatic Motor
Lateral rectus
Facial nerve (CN VII)
Both
Somatic (Branchial) Motor
Muscles of facial expression

Visceral Motor (Parasympathetic)

Submandibular, sublingual, lacrimal, and nasal glands

Somatic Sensory

Small area of skin on external ear
Special SensoryTaste from anterior 2/3 of tongue
Vestibulocochlear nerve (CN VIII)
Sensory
Special Sensory

Position and movements of head and hearing

Glossopharyngeal nerve (CN IX)
Both
Somatic (Branchial) Motor
Stylopharyngeus muscle

Visceral Motor (Parasympathetic)

Parotid gland

Visceral Sensory

Oropharynx and carotid sinus and body

Taste from posterior 1/3 of tongue
Special Sensory
Vagus nerve (CN X)
Both
Somatic (Branchial) Motor
Muscles of larynx and pharynx

Visceral Motor (Parasympathetic)

Heart, lungs, and muscle and glands of the GI tract and abdominal viscera


Visceral Sensory

Larynx, pharynx, heart, lungs, and abdominal viscera

Taste from epiglottis and laryngopharynx
Special Sensory
Accessory nerve (CN XI)
Motor
Somatic Motor
Sternocleidomastoid and Trapezius
Hypoglossal nerve (CN XII)
Motor
Somatic Motor
Muscles of the tongue
UNLABELED DIAGRAMS

Preguntas

Preguntas del estilo USMLE Step 1

de completadas

An examiner touches the forehead, cheeks, and chin of a patient with a cotton wisp to test the sensation of light touch in these regions. Which of the following cranial nerves is tested by the examiner?  

Anclajes de memoria y contenidos de colaboraciones

Transcript

Watch video only

The cranial nerves are 12 paired nerves that arise from the brain and travel through foramina and fissures in the cranium to innervate various structures, primarily in the head and neck.

Just like spinal nerves, which originate from the spinal cord, cranial nerves originate from the brain, but unlike spinal nerves which are pretty similar to each other - with all of them being mixed nerves - the cranial nerves are a mix and match of motor, sensory and autonomic functions.

Simply put, some cranial nerves are motor nerves, some are sensory nerves, some are mixed and some carry parasympathetic fibers as well.

Funnily enough, some of them aren’t even nerves at all.

The first and second cranial nerves, which are the olfactory and optic nerves, are actually brain projections that belong to the olfactory and optic tracts, but everyone likes to call them cranial nerves so we will too!

Let’s start by naming the 12 pairs of cranial nerves in order from rostral, or front of the brain, to the caudal, or back of the brain, on an image of the ventral surface of the brain: 1st Olfactory, 2nd Optic, 3rd Oculomotor, 4th Trochlear, 5th Trigeminal, 6th Abducens, 7th Facial, 8th Vestibulocochlear, 9th Glossopharyngeal, 10th Vagus, 11th Accessory, and 12th Hypoglossal.

There are many mnemonics out there to help you remember these so choose one that best fits you, but here at Osmosis we like to remember these nerves by saying:

Oh Oh Oh To Touch And Feel Very Green Vegetables A H!

Now, these nerves don’t all originate from the same place and they enter or exit at different parts of the brain.

Cranial nerves one and two enter the cerebrum, but most of the cranial nerves enter or exit at various levels of the brainstem.

Resumen

The cranial nerves are a set of 12 nerves that originate in the brainstem and exit the skull through openings in the base of the skull. They control several important functions such as vision, smell, hearing, and facial movement.

The 12 cranial nerves are olfactory (I), optic (II), oculomotor (III), trochlear (IV), trigeminal (V), abducens (VI), facial (VII), vestibulocochlear (VIII), glossopharyngeal (IX), vagus nerve(X) , accessory nerve(XI) , and hypoglossal nerve(XII).

Elsevier

Copyright © 2024 Elsevier, its licensors, and contributors. All rights are reserved, including those for text and data mining, AI training, and similar technologies.

Cookies are used by this site.

USMLE® is a joint program of the Federation of State Medical Boards (FSMB) and the National Board of Medical Examiners (NBME). COMLEX-USA® is a registered trademark of The National Board of Osteopathic Medical Examiners, Inc. NCLEX-RN® is a registered trademark of the National Council of State Boards of Nursing, Inc. Test names and other trademarks are the property of the respective trademark holders. None of the trademark holders are endorsed by nor affiliated with Osmosis or this website.

RELX