Question

Choose 3 cranial nerves. Tell me if they are sensory, motor or mixed, their number, their location, and their function in detail. Tell me why you chose the 3 cranial nerves you did and why you think they are unique or important or interesting to you. Type one-one 1/2 pages-double spaced.

Answer 1

Olfactory nerve
Olfactory nerve is the 1st cranial nerve. It is purely sensory
and carries the sense of smell from nasal cavity
Unique Features
1. The primary sensory neurons of olfactory nerve lie on
the body surface in the epithelial lining of the nasal
cavity and their dendrites lie free in the mucous film.
2. The primary sensory neurons of olfactory nerve
(olfactory neurons) undergo continuous turnover, i.e.,
they are continuously replaced by stem cells in the
olfactory neuroepithelium.
Functional Components
Special somatic afferent fibres: They carry special sensations
of smell from the olfactory region of the nasal cavity and
terminate in the olfactory bulb.
Course, Relations, and Distribution
Each olfactory nerve consists of about 20 minute bundles
of non-myelinated nerve fibres. They arise from primary
receptor neurons (modified bipolar neurons) of the
olfactory epithelium of nasal cavity, pass through foramina
in the cribriform plate of the ethmoid to enter the anterior
cranial fossa, where they terminate in the olfactory bulb. In
the olfactory bulb, they synapse with the mitral cells. The
bundles of olfactory nerves are surrounded by three
meninges (namely pia mater, arachnoid mater, and dura
mater) near the cribriform plate. This provides a potential
communication between the subarachnoid space and
lymphatics of the nasal mucosa. Thus, infection from nose
can spread into the meninges of the brain.
Distribution: olfactory region of the nasal cavity.

OPTIC NERVE
Optic nerve is the 2nd cranial nerve. It is purely sensory and responsible for vision; hence, it is also called the nerve of sight.
Unique Features
The optic nerve is not a true peripheral (cranial) nerve. It is
actually a tract of brain for it develops as an outgrowth of
diencephalon during embryonic life. Hence, it presents the
following unique features:
1. It consists of second-order sensory neurons.
2. Its fibres are myelinated by oligodendrocytes.
3. It is surrounded by meninges.
4. Its fibres cannot regenerate if cut/damaged.
Functional Component
Special somatic afferent fibres: They carry sense of sight from the visual field of the corresponding eye.
Course and Relations
The fibres of optic nerve arise from ganglion cells (second-
order neurons) in the neural layer of the retina of the eyeball, converge toward the optic disc at the posterior pole of the eyeball, pierce the outer layer of retinachoroid, and sclera to leave the eyeball. Immediately after emerging from the eyeball, the fibres unite to form the optic nerve, which passes posteromedially through the posterior half of the orbit andenters the middle cranial fossa through the optic canal. In the middle cranial fossa, optic nerves of two sides unite to form the optic chiasma. The midregion of optic chiasma is composed of crossed fibres from the medial/nasal halves of the retina of both eyes, while the lateral region is made up of fibres from the lateral/temporal half of the retina of the ipsilateral eye.
Diverging from the chiasma are the optic tracts. Most of
the fibres of the optic tract relay in the lateral geniculate body.
The third-order neurons arise in the lateral geniculate body, run in the retrolenticular part of the internal capsule, and form optic radiations. The fibres of optic radiation terminate in and around the calcarine sulcus of the occipital lobe (visual cortex). Some of the fibres from the lateral geniculate body reach the pretectal area of the midbrain and form a part of the pathway for light reflex.

VESTIBULOCOCHLEAR NERVE
Vestibulocochlear nerve is the 8th cranial nerve. It consists of two distinct parts: (a) a vestibular part, called the vestibular nerve, and (b) a cochlear part, called the cochlear nerve .The vestibular nerve is concerned with the
maintenance of equilibrium, while the cochlear nerve is
concerned with hearing.   
Functional Component and Nuclei
Special somatic afferent fibres: They carry sensory infor-
mation necessary for the maintenance of equilibrium and
hearing from the membranous labyrinth of the internal ear.
The fibres carrying the sensory information for equilib-
rium terminate in the vestibular nuclei within the brainstem.
The fibres carrying the sensory information for hearing
terminate in the dorsal and ventral cochlear nuclei, located
respectively on the dorsal and ventral aspects of the inferior
cerebellar peduncle.
Course and Relations
The vestibular nerve arises from the lateral aspect of the
pontomedullary junction, passes through the pontocerebel-
lar angle and enters the internal acoustic meatus along with
the facial nerve and labyrinthine vessels.
The vestibular ganglion (also called Scarpa’s ganglion) is
located on the vestibular nerve in the lateral part of the inter-
nal acoustic meatus. It consists of bipolar sensory neurons.
In the lateral part of the internal acoustic meatus, the nerve
divides into three distinct branches: superior and inferior
divisions and singular nerve. These branches pass through
the foramina in the fundus of the meatus and innervate the
sensory receptors for equilibrium (cristae ampullaris and
maculae) in the membranous labyrinth of the internal ear.
The cochlear nerve also arises from the lateral aspect of
the pontomedullary junction and takes a similar course to
enter the internal acoustic meatus. At the medial end of
the internal acoustic meatus, it enters into bony labyrinth
of the middle ear through tractus spiralis foraminosus in
the fundus of the meatus and reaches the modiolus of the
internal ear. In the modiolus, the cochlear nerve possesses
a sensory ganglion called the spiral ganglion made of
bipolar neurons. The peripheral process of these neurons
innervates the sensory receptor of hearing—the organ of
Corti.

i selected these three nerves because smell , vision and hearing is important in our daily life basis and these netves help us to achieve that.