This document provides an overview of the twelve cranial nerves, detailing their functions and anatomical significance. Each nerve, from the olfactory to the glossopharyngeal, is described in terms of its sensory and motor roles, particularly in relation to the head and neck. The document serves as an educational resource for understanding the cranial nervous system's functions.

1. Assignment
Physiology
Roll No: Bsmls-S20-029.
Submitted To: Dr. Saba.
Submitted By: Salman
Akram.
Superior
University
Lahore.
Introduction of cranial
nerves:
From:
ZEESHAN ALI.
BSMLS 2B.
BSMLS-F19-152.
Submitted to:
Mam Saba Farooq.
Superior Universty
Lahore.

2. Carnial nerves:
Introduction:
“Cranial nerves are the nerves that emerge directly
from the brain (including the brainstem), of which
there are conventionally considered twelve pairs.”
Cranial nerves relay information between the brain and parts of
the body, primarily to and from regions of the head and neck,
including the special senses of vision, taste, smell,
and hearing.
The 12 Cranial Nerves
 I. Olfactory nerve.
 II. Optic nerve.
 III. Oculomotor nerve.
 IV. Trochlear nerve.
 V. Trigeminal nerve.
 VI. Abducens nerve.
 VII. Facial nerve.
 VIII. Vestibulocochlear nerve.
 Ix. Accessory nerve.
 X. vagus nerve.
 Xi. Glossophyngeal nerve.
 Xii. Hypoglossal nerve.

3. Figure: Cranial nerves.
Olfactory nerve:
The olfactory nerve is typically considered the first cranial
nerve, or simply CN I, that contains sensory nerve fibers
relating to the sense of smell
Function:
The afferent nerve fibers of the olfactory receptor
neurons transmit nerve impulses about odors to
the central nervous system, where they
are perceived as smell (olfaction).
Figure: Olfactory Nerve.

4. Optic nerve:
The optic nerve, also known as cranial nerve II, or
simply as CN II, is a paired cranial nerve that
transmits visual information from the retina to
the brain
Function:
The optic nerve transmits all visual information
including brightness perception, color
perception and contrast (visual acuity).
Figure: Optic nerve.

5. Oculomotor nerve:
The oculomotor nerve is the third cranial nerve (CN
III). It enters the orbit via the superior orbital
fissure and innervates extrinsic eye muscles that
enable most movements of the eye and that raise the
eyelid.
Function:
The oculomotor nerve include axons of type
GSE, general somatic efferent, which innervate skeletal
muscle of the levator palpebrae superioris, superior
rectus, medial rectus, inferior rectus, and inferior
oblique muscles.(innervates all the extrinsic muscles
except superior oblique and lateral rectus.).
Figure: Oculomotor Nerve.

6. Trochlear nerve:
The trochlear nerve also controls the constriction of
the pupils and thickening of the lens of the eye. This
can be tested in two main ways. By moving a finger
toward a person's face to induce accommodation,
their pupils should constrict.
Function:
The trochlear nerve provides motor supply to
the superior oblique muscle of the eye, The trochlear
nerve carries axons of type GSE, general somatic
efferent, which innervate skeletal muscle of the
superior oblique muscle.
Figure: Trochlear Nerve.

7. Trigeminal nerve:
The trigeminal nerve (the fifth cranial nerve, or
simply CN V) is a nerve responsible for sensation in
the face and motor functions such as biting and
chewing.
Function:
The sensory function of the trigeminal nerve is to
provide tactile, proprioceptive,
and nociceptive afference to the face and mouth. Its
motor function activates the muscles of mastication,
the tensor tympani, tensor veli
palatini, mylohyoid and the anterior belly of the
digastric.
Figure: Trigeminal Nerve.

8. Abducens nerve:
The abducens nerve (or abducent nerve) is the
sixth cranial nerve (CNVI), in humans, that controls the
movement of the lateral rectus muscle, responsible for
outward gaze. It is a somatic efferent nerve.
Function:
The abducens nerve supplies the lateral rectus
muscle of the human eye. This muscle is
responsible for outward gaze[
The abducens
nerve carries axons of type GSE, general somatic
efferent.
Figure: Abducens Nerve.

9. Facial nerve:
The facial nerve is the seventh cranial nerve, or simply CN VII.
It emerges from the pons of the brainstem, controls the
muscles of facial expression, and functions in the conveyance
of taste sensations from the anterior two-thirds of
the tongue.The nerves typically travels from the pons through
the facial canal in the temporal bone and exits the skull at
the stylomastoid foramen.
Function:
The main function of the facial nerve is motor control of all of
the muscles of facial expression. It also innervates the
posterior belly of the digastric muscle, the stylohyoid muscle,
and the stapedius muscle of the middle ear. All of these
muscles are striated muscles of branchiomeric origin
developing from the 2nd pharyngeal arch.
Figure: Facial Nerve.

10. Vestibulocochear nerves:
The vestibulocochlear nerve (auditory vestibular nerve),
known as the eighth cranial nerve, transmits sound and
equilibrium (balance) information from the inner ear to
the brain.
Function:
This is the nerve along which the sensory cells
(the hair cells) of the inner ear transmit information to
the brain. It consists of the cochlear nerve, carrying
information about hearing, and the vestibular nerve,
carrying information about balance. It emerges from
the pontomedullary junction and exits the
inner skull via the internal acoustic meatus (or internal
auditory meatus) in the temporal bone.
Figure: Vestibulocochlear Nerve.

11. Accessory nerve:
The accessory nerve is a cranial nerve that supplies
the sternocleidomastoid and trapezius muscles. It is
considered as the eleventh of twelve pairs of cranial
nerves, or simply cranial nerve XI.
Function:
The spinal component of the accessory nerve
provides motor control
sternocleidomastoid and trapezius muscles.[7]
T
he trapezius muscle controls the action of
shrugging the shoulders, and the
sternocleidomastoid the action of turning the
head.
.
Figure: Accesory Nerve.

12. Vagus nerve:
The vagus nerve, historically cited as
the pneumogastric nerve, is the tenth cranial
nerve or CN X, and interfaces with
the parasympathetic control of the heart, lungs,
and digestive tract.
Figure: Vegus Nerve.

13. Glossophyngeal nerve:
The glossopharyngeal nerve, known as the
ninth cranial nerve (CN IX), is a mixed nerve that
carries afferent sensory and efferent motor
information. It exits the brainstem out from the sides
of the upper medulla, just anterior (closer to the nose)
to the vagus nerve. The motor division of the
glossopharyngeal nerve is derived from the basal
plate of the embryonic medulla oblongata, while the
sensory division originates from the cranial neural
crest.
Figure: Glossophyngeal Nerve.