BRAIN & CRANIAL NERVE

Prepared By:

Dr.Hemal R. Brahmkshatriya

MDS PartI

Under guidance of:

Dr. Kiran Desai sir Dr. Navin Shah sir Dr. Rakesh Shah sir Dr. Kruti Shah mam Dr. Amit Mahajan sir Dr. Dixit Shah sir Dr. Rohit Tatu sir Dr. Prachur Kumar sir Dr. Rushit Patel sir

CONTENTS Introduction

Brain Cranial nerve Cranial nerve v\s Spinal Nerve

Topography of nerves. Functional Anatomy of Cranial nerves. Examination of Cranial nerves. Surgical Aspects of Nerves.

Central Nervous System

Parts of Brain:

1. Forebrain (prosencephalon)

a) Telencephalon (cerebrum)

b) Diencephalon (thalamecephalon)

2. Midbrain (mesencephalon)

3. Hindbrain (rhombencephalon)

a) Metencephalon (pons+ cerebellum)

b) Myelencephalon or medulla oblongata.

Cerebrum

Anatomy Frontal lobe Parietal lobe Occipital lobe Precentral gyrus Postcentral gyrus

Functions Sensory cortex Motor cortex Emotion Intellectual processes Auditory Visual Speech

Brain Stem

Anatomy: Medulla oblongata Pons Midbrain

Medulla:

-Relays motor and sensory information.

-Regulates heartbeat, breathing and blood vessel dilation.

Pons: Control breathing. Mid Brain:

 vision, hearing, motor control, sleep/wake, arousal (alertness), and temperature regulation

Protective Coverings(Meninges) Dura mater:

Dense connective tissue. Arachnoid:

Nonvascular connective tissue. Pia mater:

Highly vascular.

Covers surface of the brain and spinal cord and invaginates along cortical surface to form perivascular spaces.

Cerebral Spinal Fluid Formed in the choroid plexus of leteral ventricles

and 3rd and 4th ventricles, capillaries of brain and spinal cord.

Total contain 150 ml formation rate 500ml/day. Absorbed arachnoid villi layer to cranial venous

sinus, spinal nerve. Protects, nutritive and pathways for metabolisum.

Cranial nerve:

Nerves that emerge directly from the brain (spinal nerves emerge from segments of the spinal cord).

12 pairs of cranial nerves.!!!!!?

Numbered Anterior to Posterior Attach to Ventral surface of brain Exit brain through foramina in skull I + II attach to Forebrain III-XII attach to Brainstem (midbrain, pons,

medulla) Only X goes beyond the head-neck

Cranial nerve v/s spinal nerve

Contain inflow/outflow of brain; spinal nerves contain inflow/outflow of spinal cord.

Certain types of similar to those found in spinal nerves; ex. Sensory axons to skin.

Certain types of neurons not found in spinal nerves; ex. taste fibers.

Many cranial nerves contain more than one type of neuron.

BASIS OF CLASSIFICATION

1) First letter: G = General = types of neurons found both in spinal nerves and cranial nerves. S = Special = types of neurons only found in cranial nerves not spinal nerves.2) Second letter: S = Somatic = types of neurons innervating structures derived from somites. V = Visceral = types of neurons innervating gut, structures derived from or associated with gut and brachial arches; also vascular system, smooth muscle, internal organs and glands.3) Third letter: A = Afferent = sensory neurons. E = Efferent = motor neurons to skeletal and smooth muscle; also secretomotor neurons to glands.

A. General Innervation - like spinal cord

1. GSE (General Somatic Efferent) - motor to somatic

voluntary skeletal muscles (derived from somites).

2. GSA (General Somatic Afferent) - sensory to skin,

joints, muscle and tendon receptor endings, nasal and oral cavity.

3. GVE (General Visceral Efferent) = Autonomic

Efferents - motor to smooth muscles in general and smooth muscles of skin (arrector pilae muscles) and blood vessels, secretomotor to glands.

4. GVA (General Visceral Afferent) - sensory to gut and its derivatives, pharynx, blood vessels, glands and internal organs.

B. Special Innervation - only found in head.

1. SSA (Special Somatic Afferent) - special senses of vision, auditory sensation and vestibular apparatus.

2. SVA (Special Visceral Afferents) – chemical senses of taste and by analogy smell.

3. SVE (Special Visceral Efferents) - motor to voluntary skeletal muscles derived from branchial arches (these muscles develop in association with pharynx, which is rostral end of gut and therefore visceral).

Oh! Oh! Oh! To Touch And Feel Very GoodVelvet! At Heaven! Ⅰ Olfactory nerve Ⅱ Optic nerve Ⅲ Oculomotor nerve Ⅳ Trochlear nerve Ⅴ Trigeminal nerve Ⅵ Abducent nerve Ⅶ Facial nerve Ⅷ Vestibulocochlear nerve Ⅸ Glossopharyngeal nerve Ⅹ Vagus nerve Ⅺ Accessory nerve Ⅻ Hypoglossal nerve

According to functions

Sensory cranial nerves: contain only afferent (sensory) fibersⅠOlfactory nerve ⅡOptic nerve Ⅷ Vestibulocochlear nerve

Motor cranial nerves: contain only efferent (motor) fibers Ⅲ Oculomotor nerve Ⅳ Trochlear nerve Ⅵ Abducent nerve Ⅺ Accessory nerve Ⅻ Hypoglossal nerve

Mixed nerves: contain both sensory and motor fibers---

ⅤTrigeminal nerve Ⅶ Facial nerveⅨGlossopharyngeal nerveⅩVagus nerve

Mnemonic for CN FunctionI. SomeII. SayIII. MarryIV. MoneyV. ButVI. MyVII. BrotherVIII. SaysIX. BigX. BrainsXI. MatterXII. Most!

S = Sensory functionM = MotorfunctionB = BOTH (Sensoryand Motor function

Cooks Out Spurt Some Spunk Right Over Silly Isabel's Incredible Jiggling Jizz Jet hole Cribiform plate (Olfactory) Optic canal (Optic) Superior Orbital

Fissure(Oculomotor) Superior Orbital

Fissure(Trochlear) Superior Orbital

Fissure(Trigeminal - Ophthalmic)

Foramen Rotundum (Trigeminal- Maxillary),

Foramen Ovale (Trigeminal -Mandibular),

Superior Orbital Fissure(Abducens)• Internal Acoustic Meatus(Facial)• Internal Acoustic Meatus(Vestibulocochlear)• Jugular Foramen(Glossopharyngeal)• Jugular Foramen (Vagus)• Jugular Foramen (Accessory)• Hypoglossal Canal(Hypoglossal)