How many pairs of cranial nerves are there?
12
What do cranial pass through in the skull?
Foramina and fissures
All nerves are distributed i the head and neck except for?
Cranial nerve X
What cranial nerves are entirely sensory?
- Olfactory- optic - vestibulocochlear
What cranial nerves are entirely motor?
- Oculomotor - trochlear - abducens - accessory - hypoglossal
What is the first cranial nerve called?
Olfactory nerves
What reacts to odors, stimulating the olfactory nerves?
Olfactory hairs
By what cells are the olfactory nerves myelinated?
Schwann cells
Where do olfactory nerves synapse?
On mitral and tufted cells located in the olfactors bulb.
What forms the olfactory tract?
Axons from the mitral and tufted cells
What function does the olfactory tract accomplish?
Function of smell
What are the secondary connections throughout the cortex of olfactory nerves responsible for?
Appreciation/triggering of emotional and autonomic responses to the detected smell.
What do fibers of the optic nerves represent?
Axons of ganglion cells from the retina.
How do the optic nerves flow?
Leaves the orbital cavity through the optic canal and unites with the nerve of the opposite side to form the optic chiasma.
Where does the optic tract arise from?
The optic chiasma
Where do most fibers of the optic tract synapse?
Lateral geniculate body of the thalamus
Where do fibers of the optic tract synapse if not in the lateral geniculate nucleus?
They project to the pretectal nucleus and the superior colliculus
What nerve is the III cranial nerve?
Oculomotor nerve
What does the oculomotor nerve do?
Controls the movement of extra ocular muscles and the smooth muscles of the iris and ciliary muscles for the actions of constriction and accommodation.
Where do the oculomotor nerve fibers exit the midbrain through?
Interpeduncular fossa and exit cranial cavity through the superior orbital fissure.
What cranial nerve is number IV?
Trochlear nerve
How do the trochlear nerves exit the cranial cavity?
They pass anteriorly around the midbrain and exit via the superior orbital fissure (innervating the superior oblique muscles of the eyeball)
What cranial nerve is number V?
Trigeminal nerve
What cranial nerve is the largest?
trigeminal nerve
What does the trigeminal nerve do?
Carries sensation to the head and motor control to the muscles of mastication.
How many and what nuclei does the trigeminal nerve have?
1. Sensory nucleus (main) 2. Spinal sensory nucleus 3. Mesencephalic sensory nucleus 4. Motor nucleus
In what does pain, temperature, touch and pressure travel along?
Axons whose cell bodies are located in the semilunar or trigeminal sensory ganglion.
by what fibers is touch and pressure conveyed?
Fibers that synapse in the main sensory nucleus of the trigeminal nerve
by what fibers is pain and temperature conveyed?
Fibers that synapse in the spinal nucleus of the trigeminal nerve
Where do proprioceptive fibers from the muscles of the face, orbit, mouth and mastication synapse?
Mesencephalic nucleus of the trigeminal nerve
What forms the trigeminal nerve?
Ophthalmic nerve (v1), maxillary nerve (v2) and mandibular nerve (v3)
What cranial nerve is number VI?
Abducens nerve
Where do the motor fibers from the abducens nerve nucleus exit the brainstem?
At the junction of the pons and medulla oblongata.
Where does the abducens nerve exit the cranial cavity?
Superior orbital fissure, to the orbit (innervates lateral rectus muscle of the eyeball)
What cranial nerve is number VII?
Facial nerve
Where do the fibers of the facial nerve originate from?
The main motor nucleus, superior salivatory, lacrimal and nucleus of the tractus solitarious.
Where do the motor fibers of the facial nerve exit the cranial cavity?
Internal acoustic meatus where they join the sensory root stemming from the geniculate ganglion.
What do the fibers from the motor nucleus of the facial nerve innervate?
The. Muscles of facial expression, the stapedius, the posterior belly of the digastric and the stylohyoid muscles
What do the fibers from the superior salivatory nucleus of the facial nerve supply?
The submandibular and sublingual salivary glands.
What does the lacrimal nucleus supply?
The lacrimal gland
What fibers of the facial nerve does the sensory nucleus receive?
Taste fibers from the anterior two thirds of the tongue.
What cranial nerve is number VIII?
Vestibulocochlear nerve
What parts does the vestibulocochlear nerve consist of?
Vestibular nerve and the cochlear nerve
What does the vestibular nerve conduct?
Head positioning information from the utricle, saccule and semicircular canals.
Where are the cell bodies of the vestibular nerve fibers positioned?
Vestibular ganglion projecting to the vestibular nuclear complex.
What is the vestibular nuclear complex?
A group of nuclei that transmit vestibular information to the cortex and spinal cord.
What does the cochlear nerve consist of?
Bipolar cell bodies in the spiral nucleus of the cochlear with fibers conducting cochlear sensations to the anterior and posterior cochlear nuclei.
With what do second order neurons from the cochlear nuclei communicate with?
Posterior nucleus of the trapezoid body, which sends a bundle of third order fibers (lateral lemniscus) to the inferior colliculus and medial geniculate body.
What cranial nerve is number IX?
Glossopharyngeal nerve
How many nuclei does the glossopharyngeal. Nerve have and what are they ?
1. Inferior salivatory nucleus (parasympathetic) 2. Spinal trigeminal nucleus (sensory) 3. Nucleus of the tractus solitarius (sensory)
what do the motor fibers of the glossopharyngeal nerve innervate?
Stylopharyngeus muscles
What do the parasympathetic fibers of the glossopharyngeal nerve innervate?
Parotid salivary gland
Where do the sensory fibers from the pharynx and posterior third of the tongue synapse?
In the spinal trigeminal nucleus
Where do the tase and carotid sinus and body reflexes synapse?
In the nucleus solitarius
Where does the glossopharyngeal nerve exit the cranial cavity?
jugular foramen
What cranial nerve is number X?
Vagus nerve
How many nuclei does the vagus nerve have and what are they?
1. Nucleus ambiguus (motor) 2. Dorsal nucleus (parasympathetic) 3. Spinal trigeminal (sensory) 4. Nucleus of the tractus solitarius (sensory)
What do the motor fibers from the nucleus ambiguus of the vagus nerve innervate?
Constrictor muscles of the pharynx and the intrinsic muscles of the larynx.
Where do the sensory fibers conveying taste from the epiglottis and visceral afferents from the organs synapse?
Nucleus solitarius.
Where does the sensation from the mucosa of the larynx end?
Spinal nucleus of the trigeminal.
Where to are the parasympathetic fibers from the dorsal nucleus of the vagus distributed?
To involuntary muscles of the bronchi, heart, esophagus, stomach, small intestine and up to a third of the transverse colon.
Through what does the vagus nerve exit the cranial cavity?
Jugular foramen
What cranial nerve is number XI?
Accessory nerve
What fibers does the accessory nerve receive?
Efferent fibers from the nucleus ambiguus and the anterior gray column of the first five segments of the spinal cord.
What do the fibers of the accessory nerve that originate in gray columns do?
Bring about movement of the SСM and trapezius muscles.
Through what does the accessory nerve exit the cranial cavity?
Jugular foramen.
What cranial nerve is number XII?
Hypoglossal nerve
What does the hypoglossal nerve innervate?
muscles of the tongue
Where does the hypoglossal nerve exit the medulla oblongata?
Between pyramid and olive
Where does the hypoglossal nerve exit the cranial cavity?
Through the hypoglossal canal