The nervous systemChapter one

Dr. Haydar muneer Salih

Before we begin !

Define Anatomy?

• Anatomy came from Greek wordAna = up , tome = cutting

Scientific study of body structure

What is nervous system (define) ?

Nervous system is the system which responds to the internal and external environments in order to maintain the internal environment and manipulate the external environment for survival and existence

PARTS OF NERVOUS SYSTEM1. Central nervous system (CNS):a. Brain: b. Spinal cord: 2. Peripheral nervous system (PNS)It includes those parts of nervous system which lie outside the central nervous system. It consists of twelve pairs of cranial nerves, thirty one pairs of spinal nerves, somatic and special sense receptors and the autonomic nervous system

Brain

• It lies in the cranial cavity and continues as the spinal cord. It consists of following parts

1. Forebraina. Cerebrumb. Diencephalon2. Midbrain3. Hind brainpons medulla oblongatacerebellum

Brain

Brain

Spinal cord• It is also known as spinal medulla. It is the caudal,

elongated part of central nervous system which occupies the upper 2/3rd of the vertebral canal.

• spinal cord segment. There are 31 pair of spinal nerves hence, 31 spinal cord segments. These are

• 8 cervical segments• 12 thoracic segments• 5 lumbar segments• 5 sacral segments• 1 coccygeal segment

Spinal cord

Peripheral nervous systemAs mentioned earlier it consist of • 31 spinal nerves and 12 cranial nerves• Somatic nervous system: This deals with the changes

in the external environment• Autonomic nervous system: It has two components

namely:a. Sympathetic nervous systemb. Parasympathetic nervous system• It is concerned with the regulation of visceral

functions that maintain the internal homeostasis and works mostly at the unconscious level

Nerve fiber & nerve trunk

Ganglia

Synapse

CRANIAL NERVESI. OlfactoryII. OpticIII. OculomotorIV. TrochlearV. TrigeminalVI. Abducent VII. FacialVIII. VestibulocochlearIX. GlossopharyngealX. VagusXI. AccessoryXII. Hypoglossal

CRANIAL NERVES

• The olfactory I, optic II, and vestibulocochlear nerves VIII are entirely sensory;

• The Oculomotor III, trochlear IV, abducent VI, accessory XI, and hypoglossal nerves XII are entirely motor;

• And the remaining nerves are mixed.

OLIFACTORY NERVE ( CN I)

• The olfactory nerves arise from olfactory receptor nerve cells in the olfactory mucous membrane. The olfactory mucous membrane is situated in the upper part of the nasal cavity above the level of the superior concha. Bundles of these olfactory nerve fibers pass through the openings of the cribriform plate of the ethmoid bone

OLIFACTORY NERVE (CN I)

OPTIC NERVE (CN II)

• It carries special sensory fibers for vision. These fibers return information to the brain from photoreceptors in the retina. Neuronal processes leave the retinal receptors, join into small bundles, and are carried by the optic nerves to other components of the visual system in the brain. The optic nerves enter the cranial cavity through the optic canals

OPTIC NERVE (CN II)

OCULOMOTOR NERVE (CN III )

• The oculomotor nerve emerges on the anterior surface of the midbrain.

• The oculomotor nerve supplies the following:

The extrinsic muscles of the eye The intrinsic muscles of the eye

OCULOMOTOR NERVE (CN III )

TROCHLEAR NERVE (CN IV) • The trochlear nerve is the most slender

of the cranial nerves. It then passes forward through the middle cranial fossa in the lateral wall of the cavernous sinus and enters the orbit through the superior orbital fissure.

• The trochlear nerve supplies: The superior oblique muscle of the eyeball (extrinsic muscle).

ABDUCENT NERVE (CN VI)

• This small nerve emerges from the anterior surface of the hindbrain. It passes forward with the internal carotid artery through the cavernous sinus in the middle cranial fossa and enters the orbit through the superior orbital fissure. The abducent nerve supplies the lateral rectus muscle and is therefore responsible for turning the eye laterally

Vestibulocochlear Nerve (CN VIII)

• The vestibulocochlear nerve is a sensory nerve that consists of two sets of fibers: vestibular (balance) and cochlear (hearing). It attaches to the lateral surface of the brainstem, between the pons and medulla, after emerging from the internal acoustic meatus and crossing the posterior cranial fossa.

Glossopharyngeal Nerve (CN IX)• The glossopharyngeal nerve is a motor

and sensory nerve. • It emerges from the anterior surface of

the medulla oblongata.• It leaves the skull by passing through the

jugular foramen.

Glossopharyngeal Nerve (CN IX)

VAGUS NERVE (CN X)• The vagus nerve is composed of motor and

sensory fibers.• It emerges from the anterior surface of the

medulla oblongata. • The nerve leaves the skull through the jugular

foramen. The cranial root of the accessory nerve joins the vagus nerve.

• The vagus nerve descends through the neck alongside the carotid arteries and internal jugular vein within the carotid sheath

VAGUS NERVE (CN X)

ACCESSORY NERVE (CN XI)• Cranial Root

The cranial root emerges from the anterior surface of the medulla oblongata. The nerve runs laterally in the posterior cranial fossa and joins the spinal root.

• Spinal RootThe spinal root arises from nerve cells in the anterior gray column (horn) of the upper five segments of the cervical part of the spinal cord.

• The two roots unite and leave the skull through the jugular foramen

ACCESSORY NERVE (CN XI)

HYPOGLOSSAL NERVE (CN XII )• The hypoglossal nerve is a motor nerve.

It emerges on the anterior surface of the medulla oblongata, crosses the posterior cranial fossa, and leaves the skull through the hypoglossal canal. The nerve then passes

• downward and forward in the neck and crosses the internal and external carotid arteries to reach the tongue

HYPOGLOSSAL NERVE (CN XII )

Brain

CRANIAL NERVESI. Olfactory II. OpticIII. OculomotorIV. TrochlearV. TrigeminalVI. Abducent VII. FacialVIII. VestibulocochlearIX. GlossopharyngealX. VagusXI. AccessoryXII. Hypoglossal

CRANIAL NERVES

• The olfactory I, optic II, and vestibulocochlear nerves VIII are entirely sensory;

• The Oculomotor III, trochlear IV, abducent VI, accessory XI, and hypoglossal nerves XII are entirely motor;

• And the remaining nerves are mixed.

You can found / download this presentation on https://www.slideshare.net/mobile/drhaydarmuneer