Introduction+to+Cranial+Nerves

=**Objectives**=


 * 1. Review the definition and characteristics of a cranial nerve.**

Cranial nerves contain sensory and motor fibers or both that innervate muscles or glands, or carry impulses from sensory areas. They emerge through foramina in the cranium and are covered by tubular sheaths derived from cranial meninges. The twelve pairs of cranial nerves are numbered I through XII from anterior to posterior, according to their attachments to the brain.

Three cranial nerves are sensory, five are motor, and four are mixed sensory and motor. Four cranial nerves carry presynaptic parasympathetic axons as they emerge from the brainstem: CN III (oculomotor nerve), CN VII (facial nerve), CN IX (glossopharyngeal nerve), and CN X (vagus nerve). There are are //no// sympatheic afferents in cranial nerves.

The fibers of cranial nerves connect centrally to cranial nerve nuclei – groups of neurons in which sensory or afferent fibers terminate and from which motor or efferent fibers originate. Except for the olfactory areas of CN I, the nuclei of cranial nerves are located in the brainstem.


 * 2. Review the components of a spinal nerve; describe the components of cranial nerves.**

There are 31 pairs of spinal nerves that emerge from segments of the spinal cord and use intervetebral foramena to leave the vertebral column. They consist of mixed nerves with motor and sensory components that distribute to the skin, muscles of the trunk, and the upper and lower limbs.

There are 12 pairs of cranial nerves that emerge directly from the brain and use named foramena to leave the skull. They consist of mixed, sensory only, or motor only nerves that distribute to the skin and muscles of the neck.


 * 3. Name the twelve cranial nerves.**


 * **Cranial Nerve** || **Nerve** || **Classic Dirty Mnemonic** || **Clean Mnemonic for Pansies** ||
 * CN I || Olfactory Nerve || Oh || Oh ||
 * CN II || Optic Nerve || Oh || Once ||
 * CN III || Oculomotor Nerve || Oh || One ||
 * CN IV || Trochlear Nerve || To || Takes ||
 * CN V || Trigeminal Nerve || Touch || The ||
 * CN VI || Abducens Nerve || And || Anatomy ||
 * CN VII || Facial Nerve || Feel || Final ||
 * CN VIII || Vestibulococlear Nerve || Virgin || Very ||
 * CN IX || Glosspharyngeal Nerve || Girls' || Good ||
 * CN X || Vagus Nerve || Vaginas || Vacations ||
 * CN XI || Accessory Nerve || And || Are ||
 * CN XII || Hypoglossal Nerve || Hymens || Heavenly ||


 * 4. For each cranial nerve, identify functional components and relative position in cranial vault.**

All of the cranial nerves can be seen on the ventral aspect of the brain except for CN I and CN IV. CN I is in the mucous membrane of the nasal cavity and CN IV exists from the dorsal surface. The twelve pairs of cranial nerves are numbered I through XII from anterior to posterior, according to their attachments to the brain.


 * **Cranial Nerve** || **Nerve** || **Origin Location** || **Components** || **Classic Dirty Mneumonic** ||
 * CN I || Olfactory Nerve || Olfactory Mucosa || Sensory || Some ||
 * CN II || Optic Nerve || Ganglion cells of neural retina || Sensory || Say ||
 * CN III || Oculomotor Nerve || Midbrain (Mesencephalon) || Motor || Marry ||
 * CN IV || Trochlear Nerve || Midbrain (Mesencephalon) || Motor || Money ||
 * CN V || Trigeminal Nerve || Pons; sensory and motor root || Both Sensory and Motor || But ||
 * CN VI || Abducens Nerve || Junction of pons and medulla || Motor || My ||
 * CN VII || Facial Nerve || Junction of pons and medulla || Both Sensory and Motor || Brother ||
 * CN VIII || Vestibulococlear Nerve || Junction of pons and medulla || Sensory || Says ||
 * CN IX || Glosspharyngeal Nerve || Medulla || Both Sensory and Motor || Big ||
 * CN X || Vagus Nerve || Medulla || Both Sensory and Motor || Breasts ||
 * CN XI || Accessory Nerve || Cranial root emerges from medulla; spinal root emerges from superior part of spinal cord || Motor || Matter ||
 * CN XII || Hypoglossal Nerve || Medulla || Motor || More ||


 * **Cranial Nerves** ||  ||   || **Motor Components** ||   ||   || **Sensory Components** ||   || **Special Sensory Components** ||   ||
 * **Nerve Number** || **Nerve Name** || **Motor Skeletal Muscle (Not from Arch)** || **Motor Skeletal Muscle (Pharyngeal Arch)** || **Motor Parasympathetic Smooth Muscle or Glands** || **Sensory Pain, Pressure, or Temperature** || **Sensory Pain from Organs or Mucous Membranes** || **Special Sensory Smell or Taste** || **Special Sensory Vision, Hearing or Balance** ||
 * CN I || Olfactory Nerve ||  ||   ||   ||   ||   || Smell ||   ||
 * CN II || Optic Nerve ||  ||   ||   ||   ||   ||   || Vision ||
 * CN III || Oculomotor Nerve || Extraocular muscles ||  || Pupillary sphincter, ciliary muscles ||   ||   ||   ||   ||
 * CN IV || Trochlear Nerve || Superior oblique muscle (one of extraocular muscles) ||  ||   ||   ||   ||   ||   ||
 * CN V1 || Trigeminal Nerve – Ophthalmic ||  ||   ||   || Skin of superior face: forehead, upper eyelid, temple, cornea ||   ||   ||   ||
 * CN V2 || Trigeminal Nerve – Maxillary ||  ||   ||   || Skin of middle face: cheeks, upper teeth, nasal cavity, upper lip ||   ||   ||   ||
 * CN V3 || Trigeminal Nerve – Mandibular ||  || Muscles of mastication ||   || Skin of inferior face: lower teeth, chin, tongue ||   ||   ||   ||
 * CN VI || Abducens Nerve || lateral rectus muscle (one of extraocular muscles) ||  ||   ||   ||   ||   ||   ||
 * CN VII || Facial Nerve ||  || Muscles of facial expression || Lacrimal glands, mucous glands of nasal cavity, salivary glands of oral cavity || External ear ||   || Taste of anterior 2/3 of the tongue ||   ||
 * CN VIII || Vestibulococlear Nerve ||  ||   ||   ||   ||   ||   || Hearing and Balance ||
 * CN IX || Glosspharyngeal Nerve ||  || Stylopharyngius muscle || Parotid gland (salivary) ||   || Mucous membrane of the pharynx and posterior tongue || Taste of posterior 1/3 of the tongue ||   ||
 * CN X || Vagus Nerve ||  || Skeletal muscles of the palate, pharynx and larynx || Cardiac muscle, smooth muscle of thorax and abdomen, mucus glands in pharynx and larynx ||   || Organs of thorax and abdomen and mucous glands from pharynx and larynx || Taste in area of the epiglotis ||   ||
 * CN XI || Accessory Nerve || Sternocleidomastoid muscle, trapezius ||  ||   ||   ||   ||   ||   ||
 * CN XII || Hypoglossal Nerve || Intrinsic and extrinsic muscles of the tongue ||  ||   ||   ||   ||   ||   ||


 * 5. Name and describe ganglia that are associated with the cranial nerves.**


 * **Cranial Nerve** || **Nerve** || **Ganglion** || **Foramen** ||
 * CN I || Olfactory Nerve || Anterior Olfactory Nucleus || Cribiform Plate ||
 * CN II || Optic Nerve || Lateral Geniculate Nucleus || Optic Canal ||
 * CN III || Oculomotor Nerve || Oculomotor nucleus, Edinger-Westphal nucleus || Superior Orbital Fissure ||
 * CN IV || Trochlear Nerve || Trochlear nucleus || Superior Orbital Fissure ||
 * CN V || Trigeminal Nerve || Principal sensory trigeminal nucleus, Spinal trigeminal nucleus, Mesencephalic trigeminal nucleus, Trigeminal motor nucleus || Superior Orbital Fissure, Foramen Rotundum, Foramen Ovale ||
 * CN VI || Abducens Nerve || Abducens nucleus || Superior Orbital Fissure ||
 * CN VII || Facial Nerve || Facial nucleus, Solitary nucleus, Superior salivary nucleus || Internal Auditory Meatus, Stylomastoid Foramen, Hiatus of Facial Canal, Petrotympanic Fissure ||
 * CN VIII || Vestibulococlear Nerve || Vestibular nuclei, Cochlear nuclei || Internal Auditory Meatus ||
 * CN IX || Glosspharyngeal Nerve || Nucleus ambiguus, Inferior salivary nucleus, Solitary nucleus || Jugular Foremen ||
 * CN X || Vagus Nerve || Nucleus ambiguus, Dorsal motor vagal nucleus, Solitary nucleus || Jugular Foramen ||
 * CN XI || Accessory Nerve || Nucleus ambiguus, Spinal accessory nucleus || Jugular Foramen ||
 * CN XII || Hypoglossal Nerve || Hypoglossal nucleus || Hypoglossal Canal ||


 * 6. Be able to differentiate between sensory ganglia and autonomic ganglia.**

=**Supplementary Materials**=