Nervous Tissue Neurons: specialized nerve cells conduct impulses Cell body, dendrite, axon Interneuron: between motor & sensory neuron in CNS

Neurons 3

The Neuron Neuron Dendrites: Collects information from other neurons. Cell Body Axon: Transmits information to other neurons. Click image to play or pause video

Cells of the Nervous System Neurons – structural classes Multipolar Unipolar Bipolar Interneurons Glial cells – various types, provide a wide variety of supportive functions

Ganglia Collections of neuron cell bodies outside the CNS

Nervous System Central nervous system Peripheral nervous system Brain Spinal cord Peripheral nervous system Cranial nerves Spinal nerves Ganglia Autonomics

Parts of CNS Cerebrum Cerebellum Mid brain Pones Medulla oblongata Spinal cord

Brain

The Meninges The meninges are layers of tissue that separate the skull and the brain. Skull Dura mater Arachnoid Layer Pia Mater Brain

Functions of spinal cord Located safely in spinal canal Length is 45cm, which extends up to first lumber vertebra 31 pairs of peripheral nerves starts from spinal cord Functions of spinal cord To propagate sensory stimuli from organs to the brain To carry commands from the brain towards the organs Reflex action

Anatomy of the Spinal Cord

Spinal Nerves At 31 places along the spinal cord the dorsal and ventral roots come together to form spinal nerves. Spinal nerves contain both sensory and motor fibers, as do most nerves. Spinal nerves are given numbers which indicate the portion of the vertebral column in which they arise. There are 8 cervical (C1-C8), 12 thoracics (T1-T12), 5 lumbar (L1-L5), 5 sacral (S1-S5), and 1 coccygeal nerve. Nerve C1 arises between the cranium and atlas (1st cervical vertebra) and C8 arises between the 7th cervical and 1st thoracic vertebra. All the others arise below the respective vertebra or former vertebra in the case of the sacrum. Since the actual cord ends at the second lumbar vertebra, the later roots arise close together on the cord and travel downward to exit at the appropriate point. These nerve roots are called the cauda equina because of their resemblance to a horses tail.

Anatomy of the Spinal Cord

Spinal Cord Extends from foramen magnum to second lumbar vertebra Segmented Cervical Thoracic Lumbar Sacral Gives rise to 31 pairs of spinal nerves Not uniform in diameter throughout length

شكاف و شيارهاي موجود در سطوح نخاعي در سطح خارجي نخاع شيارهاي طولي سراسري ديده ميشوند الف- شكاف قدامي مياني (Anterior Median Fissure) ب- شيار خلفي مياني (Posterior Median Sulcus) ج- شيارهاي قدامي جانبي (Anterolateral sulcus) د- شيارهاي خلفي جانبي (Posterolateral Sulcus شياري كه سرتاسري نمي باشد: شيارهاي خلفي واسطه اي :(Posterior intermediate Sulcus) در نخاع گردني و نيمه فوقاني نخاع پشتي در هر نيمه نخاع و به صورت شياري در حد فاصل دو شيار خلفي مياني و شيار خلفي جانبي مي باشند.

Cross Section of Spinal Cord

Cross Section of Spinal Cord Gray matter: Neuron cell cell bodies, dendrites, axons ‘Horns’: Posterior (dorsal) Anterior (ventral) Lateral Commissures: Gray: Central canal White White matter: Myelinated axons forming nerve tracts Fissure and sulcus Three columns: Ventral Dorsal Lateral (see later for white matter pathways)

spinal cord brain CNS PNS The Organisation of the Nervous System spinal nerves (31p) cranial nerves (12p) PNS sensory motor motor sensory Sensory information has to be passed on from the spinal cord to the brain ascending pathways (red) Commands from the brain have to be sent out to the PNS descending pathways (green)

Spinal Cord Anatomy Central canal filled with cerebrospinal fluid Figure 7.19 Slide 7.53c Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Spinal Cord Anatomy Meninges cover the spinal cord Nerves leave at the level of each vertebrae Dorsal root Associated with the dorsal root ganglia – collections of cell bodies outside the central nervous system Ventral root Slide 7.54 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Structure of a Nerve Endoneurium surrounds each fiber Groups of fibers are bound into fascicles by perineurium Fascicles are bound together by epineurium Figure 7.20 Slide 7.56 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Classification of Nerves Mixed nerves – both sensory and motor fibers Afferent (sensory) nerves – carry impulses toward the CNS Efferent (motor) nerves – carry impulses away from the CNS Slide 7.57 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Spinal Nerves There is a pair of spinal nerves at the level of each vertebrae for a total of 31 pairs Slide 7.63 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Typical Spinal Nerve Roots (rootlets) Primary rami Dorsal = afferent = sensory Ventral = efferent = motor Primary rami Dorsal = both sensory and motor to deep back, skin overlying Motor to erector spinae, transversospinal muscles Sensory via medial, lateral cutaneous branches Ventral = both sensory and motor to rest of body

Dorsal root Dorsal 1° ramus Spinal nerve Ventral 1° ramus Ventral horn Afferent nerve fiber Efferent nerve fiber Ventral root

Ventral 1° Rami Cutaneous Branches Lateral cutaneous branch Anterior branch Posterior branch Anterior cutaneous branch Medial branch Lateral branch

Medial br. Lateral br. Anterior cutaneous branch Anterior br. Lateral cutaneous branch Dorsal root ganglion Posterior br. Ventral 1° ramus Dorsal 1° ramus

برجستگي هاي نخاع نخاع يك استوانه كامل نيست و قطر عرضي آن از قطر قدامي خلفي آن بيشتر است همچنين از بالا به پائين از قطر كلي آن كاسته مي شود. در طول نخاع دو محل برجسته ديده مي شود Cervical Enlargement) برجستگي گردني :كه محل اتصال اعصاب نخاعي مربوط به اندام هاي فوقاني بوده و ( مي باشد. T تا 2 C و تقريبا در محاذات مهره هاي 3 T تا 2 C در حد سگمان هاي 3 (Lumbar Enlargement) برجستگي كمري كه محل اتصال اعصاب نخاعي مربوط به اندام هاي تحتاني بوده و مي باشد. T9 - T و تقريبا در محاذات مهره هاي 12 L2 -S در حد سگمانهاي 3 در پائين تر از برجستگي كمري يعني از محاذات مهره 12 پشتي به پايين از قطر نخاع به سرعت كاسته شده و بالاخره نخاع در محاذات ديسك بين مهره هاي اول و دوم كمري ختم مي شود . اين قسمت آخري را به نام مخروط انتهائي مي نامند (Conus Terminale)

Spinal nerves join together in plexuses Spinal nerves join together in plexuses. A plexus is an interconnection of fibers which form new combinations as the "named" or peripheral nerves. There are four voluntary plexuses (there are also some autonomic plexuses): 1. The cervical plexus, 2. The brachial plexus, 3. The lumbar plexus, and the 4. The sacral plexus. Each plexus gives rise to new combinations of fibers as the peripheral nerves.

Plexus Intermingling of nerve fibers from more than one source Spinal nerve = of different spinal nerves Cervical Brachial Lumbar Sacral Autonomic = of different autonomic fibers

Plexuses Cervical Plexus-the phrenic nerve travels through the thorax to innervate the diaphragm. Brachial Plexus- Axillary nerve-innervates the deltoid muscle and shoulder, along with the posterior aspect of the upper arm. Musculocutaneous nerve- innervates anterior skin of upper arm and elbow flexors.･Radial nerve - innervates dorsal aspect of the arm and extensors of the elbow, wrist, and fingers, abduction of thumb.･Median nerve - innervates the middle elbow, wrist and finger flexors, adducts the thumb.･Ulnar nerve - innervates the medial aspect wrist and finger flexors. Lumbar Plexus-genitofemoral-to the external genitalia･obturator-to the adductor muscles. femoral-innervates the skin and muscles of upper thigh, including the quadriceps. Sacral Plexus gluteal nerves (superior and inferior) - superior innervates the gluteus medius and minimus, inferior innervates the gluteus maximus.･sciatic nerve - the body's largest nerve, consisting of two major branches, the tibial and common peroneal. Together they innervate most all of leg including the flexors of the knee, part of adductor magnus, muscles for plantar flexion, dorsiflexion, and other movements of the foot and toes.

The Cervical Plexus Sensory Branches (superficial) Lesser occipital- C2-skin of scalp post/sup to ear Great auricular- C2/3-skin ant/inf/over ear Transverse cervical- C2/3-skin ant neck Supraclavicular- C3/4-skin over shest /shoulder Motor Branches (deep) Ansa cervicalis- C1, 2/3 sup/inf parts: infrahyoid/geniohyoid, geniohyoid Phrenic- C3/5-diaphram Segmental branches- C1-5, deep neck, levator scapulae, mid scalenes

Cervical Plexus

The Brachial Plexus Dorsal scapular- C5-levator scapulae, rhomboids Long thoracic- C5-C7-serratus anterior Subclavius- C5/6-subclavius muscle Musculocutaneous- C5-C7-coricobrachialis, biceps, brachialis Lateral Pectoral- C5-C7-Pectoralis major Upper subscapular- C5/6-Subscapularis Thoracodorsal- C6-C8 latissimus dorsi Lower subscapular- C5/6 subscapularis and teres major Axillary- C5/6 deltoid and teres minor Median- C5-T1 flexors of forearm except carpi ulnaris, skin/muscles lat palm Radial- Triceps, extensor muscles of arm/forearm, skin Medial pectoral- C8-T1 pectoralis major and minor Medial cutaneous arm/forearm- C8-T1-skin of med and post arm/forearm Ulnar- C8-T1, flex carpi ulnaris, flex dig profundis, hand muscles skin med

Brachial plexus Intermingling fibers C5 C6 C7 C8 T1

C5 C6 T1 C8 C7

The Brachial Plexus

The Lumbar Plexus Iliohypogastric- L1-anterior lateral abdominal wall, skin inf abdomen Ilioinguinal- L1-ant lat abdominal wall, skin med thigh, genitalia Genitofemoral- L1/2-skin ant thigh, genitalia lateralcutaneous- L2/3-skin over lat/ant/post thigh Femoral- L2-L4-thigh flexors/entensors skin-med thigh and foot Obturator L2-L4-leg adductor muscles

The Sacral Plexus Superior gluteal- L4/5 and S1, gluteus minimus, medius, tensor fasciae Inferior gluteal- L5-S2 gluteus maximus Piriformis- S1/2 piriformis Quadratus femoris- L4/5 and S1-quadratus femoris Obturator- L5-S2 Obturator Perforating cutaneous- S2/3 skin over inf med buttock Posterior cutaneous- S1-S3 skin over anal region, inf lat buttock, genetialia Sciatic- L4-S3 tibial and common fibular Prudendal- S2-S4 perineum, genetalia

Lumbar and Sacral Plexuses

Dorsal root ganglion Ventral root Dorsal 1° ramus Ventral 1° ramus Autonomic (sympathetic) ganglion Lateral cutaneous branch Anterior cutaneous branch

External Brain Structures

The Meninges The meninges are layers of tissue that separate the skull and the brain. Skull Dura mater Arachnoid Layer Pia Mater Brain

Cerebrum Functions of cerebrum Biggest part of brain, divided into two hemispheres Contra lateral control Outer surface is grey due to cells Internally white due to fibers Surface is folded to increase the area Functions of cerebrum Intellect, memory, will power, imagination, emotion & other psychological functions Receive and perceive the stimuli To give command for reaction with the help of past experience To control over other parts of nervous system

The Cerebrum The largest portion of the brain is the cerebrum. It consists of two hemispheres that are connected together at the corpus callosum. The cerebrum is often divided into five lobes that are responsible for different brain functions. Corpus callosum

The Cerebrum Neocortex The cerebrum’s surface—the neocortex—is convoluted into hundreds of folds. The neocortex is where all the higher brain functions take place.

Lobes of the Cerebrum Limbic Lobe Frontal Lobe Parietal Lobe Occipital Lobe Temporal Lobe

Thalamus Thalamus means “inner room” in Greek, as it sits deep in the brain at the top of the brainstem. The thalamus is called the gateway to the cerebral cortex, as nearly all sensory inputs pass through it to the higher levels of the brain.

Hypothalamus The hypothalamus sits under the thalamus at the top of the brainstem. Although the hypothalamus is small, it controls many critical bodily functions: Controls autonomic nervous system Center for emotional response and behavior Regulates body temperature Regulates food intake Regulates water balance and thirst Controls sleep-wake cycles Controls endocrine system The hypothalamus is shaded blue. The pituitary gland extends from the hypothalamus.

Mid brain Functions of mid brain Underneath the cerebrum and above pons Functions of mid brain To control involuntary functions

Cerebellum Functions of cerebellum Situated below and behind the cerebrum Functions of cerebellum Controls tone muscles Helps coordination of body movements Helps balancing the body

Cerebellum The cerebellum is connected to the brainstem, and is the center for body movement and balance. Click image to play or pause video

The Brainstem The brainstem is the most primitive part of the brain and controls the basic functions of life: breathing, heart rate, swallowing, reflexes to sight or sound, sweating, blood pressure, sleep, and balance. The brainstem can be divided into three major sections. Detailed brainstem anatomy. Click image to play or pause video

Brainstem Components More Information: Medulla Thalamus Pons Front Rear

Brainstem Divisions Midbrain Pons Medulla Oblongata

The Medulla Oblongata The medulla oblongata merges seamlessly with the spinal cord and creates the base of the brainstem. The medulla is primarily a control center for vital involuntary reflexes such as swallowing, vomiting, sneezing, coughing, and regulation of cardiovascular and respiratory activity. The medulla is also the origin of many cranial nerves.

Functions of Medulla oblongata Pons Below mid brain Functions of pons Control of consciousness Control level of concentration Medulla oblongata Lowest part of CNS just above the spinal cord Functions of Medulla oblongata Control of respiration Control of circulation Control of swallowing and vomiting

The Pons The pons is the rounded brainstem region between the midbrain and the medulla oblongata. In fact, pons means “bridge” in Latin. The main function of the pons is to connect the cerebellum to the rest of the brain and to modify the respiratory output of the medulla. The pons is the origin of several cranial nerves.

The Ventricles The ventricles are a complex series of spaces and tunnels through the center of the brain. The ventricles secrete cerebrospinal fluid, which suspends the brain in the skull. The ventricles also provide a route for chemical messengers that are widely distributed through the central nervous system. Click image to play or pause video

Cerebrospinal Fluid Cerebrospinal fluid is a colorless liquid that bathes the brain and spine. It is formed within the ventricles of the brain, and it circulates throughout the central nervous system. Cerebrospinal fluid fills the ventricles and meninges, allowing the brain to “float” within the skull. Click image to play or pause video

The Cranial Nerves Olfactory nerve Optic nerve Oculomotor nerve Trochlear nerve Trigeminal nerve Abducens nerve Facial nerve Vestibulocochlear nerve Glossopharyngeal nerve Vagus nerve Accessory nerve Hypoglossal nerve

Brain Functions Vision Taste Cognition Emotion Speech Language Hearing Motor Cortex Sensory Cortex Autonomic Functions

Vision The visual cortex resides in the occipital lobe of the brain. Sensory impulses travel from the eyes via the optic nerve to the visual cortex. Damage to the visual cortex can result in blindness.

Speech Broca’s Area Broca’s area is where we formulate speech and the area of the brain that sends motor instructions to the motor cortex. Injury to Broca’s area can cause difficulty in speaking. The individual may know what words he or she wishes to speak, but will be unable to do so.

Language Auditory Association Area Wernicke’s area is a specialized portion of the parietal lobe that recognizes and understands written and spoken language. Wernicke’s area surrounds the auditory association area. Damage to this part of the brain can result in someone hearing speech, but not understanding it. Wernicke’s Area

Hearing There are two auditory areas of the brain: The primary auditory area (brown circle) is what detects sounds that are transmitted from the ear. It is located in the sensory cortex. The auditory association area (purple circle) is the part of the brain that is used to recognize the sounds as speech, music, or noise.

The Cranial Nerves

Cranial Nerves Olfactory (I) Optic (II) Oculomotor (III) Trochlear (IV) Trigeminal (V) Abducens (VI) Facial (VII) Vestibulocochlear (VIII) Also known as auditory Glossopharyngeal (IX) Vagus (X) Accessory (XI) Also known as spinal accessory Hypoglossal (XII)

Names of cranial nerves 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

Classification of cranial nerves Sensory cranial nerves: contain only afferent (sensory) fibers ⅠOlfactory nerve ⅡOptic nerve Ⅷ Vestibulocochlear nerve Motor cranial nerves: contain only efferent (motor) fibers Ⅲ Oculomotor nerve Ⅳ Trochlear nerve ⅥAbducent nerve Ⅺ Accessory nerv Ⅻ Hypoglossal nerve Mixed nerves: contain both sensory and motor fibers--- ⅤTrigeminal nerve, Ⅶ Facial nerve, ⅨGlossopharyngeal nerve ⅩVagus nerve

Sensory cranial nerves Location of cell body and axon categories Cranial exit Terminal nuclei Main action Ⅰ Olfactory cells (SVA) Cribrifom foramina Olfactory bulb Smell Ⅱ Ganglion cells (SSA) Optic canal Lateral geniculate body Vision Ⅷ Vestibular ganglion(SSA) Internal acoustic meatus Vestibular nuclei Equilibrium Cochlear ganglion (SSA) Cochlear nuclei Hearing

Motor cranial nerves N. Nucleus of origin and axon categories Cranial exit Main action Ⅲ Nucleus of oculomotor (GSE) Superior orbital fissure Motot to superior, inferior and medial recti; inferior obliquus; levator palpebrae superioris Accessory nucleus of oculomotor (GVE) Parasympathetic to sphincter pupillea and ciliary muscl Ⅳ Nucleus of trochlear nerve (GSE) Motor to superior obliquus Ⅵ Nucleus of abducent nerve (GSE) Motor to lateral rectus Ⅺ Nucleus of accessory nerve (SVE) Jugular foramen Motor to sternocleidomastoid and trapezius Ⅻ Nucleus of hypoglossal nerve( GSE) Hypoglossal canal Motot to muscles of tongue

Cranial Nerves Optic (II) Oculomotor (III) Olfactory (I) Sensory (smell) Optic (II) Sensory (sight) Oculomotor (III) Motor (4 of 6 eye muscles) Parasympathetic (constriction of pupil, movement of lens)

Cranial Nerves Trigeminal (V) Abducens (VI) Trochlear (IV) Motor (1 eye muscle) Trigeminal (V) Sensory (face, nasal cavity, cheeks, lips, skin of mandible) Motor (muscles of mastication, anterior belly of digastric, mylohyoid) Abducens (VI) Motor (1 eye muscle)

Cranial Nerves Vestibulocochlear (VIII) Glossopharyngeal (IX) Facial (VII) Sensory (taste) Motor (facial muscles, posterior belly of digastric) Parasympathetic (salivary glands, glands of nasal cavity) Vestibulocochlear (VIII) Sensory (hearing and balance) Glossopharyngeal (IX) Sensory (taste, back of mouth, tonsils, middle ear) Motor (1 muscle of pharynx) Parasympathetic (salivary gland, glands of tongue)

Cranial Nerves Accessory (XI) Hypoglossal (XII) Vagus (X) Sensory (taste, back of mouth, larynx, thoracic and abdominal organs) Motor (muscles of larynx, 1 muscle of tongue) Parasympathetic (thoracic and abdominal organs) Accessory (XI) Motor (sternocleidomastoid, trapezius) Hypoglossal (XII) Motor (tongue and throat muscles)

Points to Remember Cranial nerves are part of the peripheral nervous system. Carry sensory or motor information or a combination and function in parasympathetic nervous system. Cranial nerves I, II and VIII are purely sensory. Cranial nerves III, IV, VI, XI and XII are motor (although also function for proprioception).

Autonomic nervous system (Involuntary nervous system) It has control over Digestion Respiration Circulation Hormone secretion Maintenance of body temperature Maintenance of water balance Peripheral nervous system 12 pairs of cranial nerves from brain (cranial nerves) 31 pairs of spinal nerves from spinal cord (spinal nerves)

Autonomic Nervous System The involuntary branch of the nervous system Consists of only motor nerves Divided into two divisions Sympathetic division Parasympathetic division Slide 7.67 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Autonomic Nervous System Automatic Regulation of viscera Efferent (motor) 2-neuron pathway 2 antagonistic parts Sympathetic Parasympathetic

Sympathetic Nervous System Also called thoracolumbar system (T1-L2) Preganglionic cell bodies in lateral horn Preganglionic fibers leave spinal cord with ventral roots Leave spinal nerve via white rami communicans Postganglionic cell bodies in ganglia Sympathetic chain (paravertebral) Collateral (prevertebral)

Sympathetics, Continued Once in sympathetic chain, fibers may— Synapse at that level, re-enter spinal nerve via gray ramus communicans Go up the chain before (or after) synapse Go down the chain before (or after) synapse Go through without synapse in chain (as splanchnic nerves) Splanchnic nerves Postganglionic fibers go to effector organs Preganglionic fibers relatively short; postganglionic relatively long

Lateral gray column White ramus communicans Gray ramus communicans

Sympathetics - Functions Prepares body for fight or flight Increases: heart rate, blood pressure, blood flow to skeletal muscles, respiration Decreases: Peristalsis, blood supply to viscera, glandular secretion Dilates pupils (Note: no sympathetics in accommodation) Stimulates sweat glands Stimulus generalized, long-lasting

Parasympathetic Nervous System Craniosacral outflow Cranial nerves III, VII, IX, X Sacral spinal nerves 2, 3, 4 Preganglionic cell bodies in cranial nuclei, sacral spinal cord Ganglia Special ganglia in head: ciliary, pterygopalatine, submandibular, otic Intrinsic ganglia on or in organ innervated Preganglionic fibers long; postganglionic fibers short

Parasympathetics - Functions Preserve the body as a vegetative organ Decreases heart rate Increases peristalsis Constricts pupil Accommodates eye Empties bladder, rectum Stimulates salivary, lacrimal, digestive glands Stimulus discrete, localized, short-lived Note: no parasympathetics to blood vessels, sweat glands

Reflex action Protective function of the spinal cord Sensory organ Afferent nerve Sensory cell in posterior horn of spinal cord Connector nerve Motor cell in anterior horn of spinal cord Efferent nerve End organ of reaction

Functional components General somatic afferent fibers (GSA): transmit exteroceptive and proprioceptive impulses from head and face to somatic sensory nuclei Special somatic afferent fibers (SSA): transmit sensory impulses from special sense organs of vision, equilibrium and hearing to the brain General visceral afferent fibers (GVA): transmit interoceptive impulses from the viscera to the visceral sensory nuclei Special visceral afferent fibers (SVA): transmit sensory impulses from special sense organs of smell and taste to the brain General somatic efferent fibers (GSE): innervate skeletal muscles of eye and tongue Special visceral efferent fibers (SVE): transmit motor impulses from the brain to skeletal muscles derived from brachial (gill) arches of embryo. These include the muscles of mastication, facial expression and swallowing General visceral efferent fibers (GVE): transmit motor impulses from the general visceral motor nuclei and relayed in parasympathetic ganglions. The postganglionic fibers supply cardiac muscles，smooth muscles and glands

Olfactory nerve Olfactory mucosa (SVA)→ Cribriform foramina → Olfactory bulb

Optic nerve Ganglion cell (SSA) → Optic canal → Lateral geniculate body

Vestibulocochlear nerve Vestibular ganglion(SSA) ↘ ↗ Vestibular nuclei Internal acoustic meatus Cochlear ganglion (SSA) ↗ ↘ Cochlear nuclei

Oculomotor nerve Oculomotor nerve Components Main action－supplies General somatic efferent fibers (GSE) General visceral efferent fibers (GVE) Main action－supplies Superior, inferior and medial recti; inferior obliquus; levator palpebrae superioris Sphincter pupillea and ciliary muscle Ciliary ganglion: lies between optic nerve and lateral rectus Oculomotor nerve

Accessory nerve Abducent nerve

Hypoglossal nerve Hypoglossal nerve

Oculamotor paralysis Abducent nerve injury

Mixed cranial nerves

Trigeminal nerve Components of fibers SVE fibers: originate from motor nucleus of trigeminal nerve, and supply masticatory muscles GSA fibers: transmit facial sensation to sensory nuclei of trigeminal nerve, the GSA fibers have their cell bodies in trigeminal ganglion, which lies on the apex of petrous part of temporal bone

Branches Ophthalmic nerve (Ⅴ1, sensory) leave the skull through the superior orbital fissure, to enter orbital cavity Frontal nerve: Supratrochlear nerve Supraorbital nerve Lacrimal nerve Nasociliary nerve

Distribution: Sensation from cerebral dura mater Visual organ Mucosa of nose Skin above the eye and back of nose

Maxillary nerve (Ⅴ2, sensory) Leave skull through foramen rotundum Branches Infraorbital nerve Zygomatic nerve Superior alveolar nerve Pterygopalatine nerve

Distribution: Sensation from cerebral dura mater Maxillary teeth Mucosa of nose and mouth Skin between eye and mouth

Mandibular nerve (Ⅴ3, mixed) Leave the skull through the foramen ovale to enter the infratemporal fossa Branches Auriculotemporal nerve Buccal nerve Lingual nerve Inferior alveolar nerve Nerve of masticatory muscles

Distribution: Sensation from cerebral dura mater Teeth and gum of lower jaw Mucosa of floor of mouth Anterior 2/3 of tongue Skin of auricular and temporal regions and below the mouth Motor to masticatory muscles, mylohyoid, and anterior belly of digastric

Facial nerve (Ⅶ) Components of fibers SVE fibers originate from nucleus of facial nerve, and supply facial muscles GVE fibers derived from superior salivatory nucleus and relayed in pterygopalatine ganglion and submandibular ganglion. The postganglionic fibers supply lacrimal, submandibular and sublingual glands SVA fiber from taste buds of anterior two-thirds of tongue which cell bodies are in the geniculate ganglion of the facial nerve and end by synapsing with cells of nucleus of solitary tract GSA fibers from skin of external ear

Course: leaves skull through internal acoustic meatus, facial canal and stylomastoid foramen, it then enters parotid gland where it divides into five branches which supply facial muscles

Branches within the facial canal Chorda tympani : joins lingual branch of mandibular nerve To taste buds on anterior two-thirds of tongue Relayed in submandibular ganglion, the postganglionic fibers supply submandibular and sublingual glands

Greater petrosal nerve: GVE fibers pass to pterygopalatine ganglion and there relayed through the zygomatic and lacrimal nerves to lacrimal gland Stapedial nerve : to stapedius

Branches outside of facial canal Temporal Zygomatic Buccal Marginal mandibular Cervical

Pterygopalatine ganglion : lies in pterygopalatine fossa under maxillary nerve Submandibular ganglion : lies between lingual nerve and submandibular gland

Injury to the facial nerve

Glossopharyngeal nerve (Ⅸ) Components of fibers SVE fibers: originate from nucleus ambiguus, and supply stylopharygeus GVE fibers: arise from inferior salivatory nucleus and ralyed in otic ganglion, the postganglionic fibers supply parotid gland SVA fibers: arise from the cells of inferior ganglion, the central processes of these cells terminate in nucleus of solitary tract, the peripheral processes supply the taste buds on posterior third of tongue GVA fibers: visceral sensation from mucosa of posterior third of tongue, pharynx, auditory tube and tympanic cavity, carotid sinus and glomus, and end by synapsing with cells of nucleus of solitary tract GSA fibers: sensation from skin of posterior surface of auricle and

Course: leaves the skull via jugular foramen Branches Lingual branches : to taste buds and mucosa of posterior third of tongue Pharyngeal branches : take part in forming the pharyngeal plexus Tympanic nerve : GVE fibers via tympanic and lesser petrosal nerves to otic ganglion, with postganglionic fibers via auriculotemporal (Ⅴ3) to parotid gland Carotid sinus branch : innervations to both carotid sinus and glomus Others: tonsillar and stylophayngeal branches Otic ganglion : situated just below foramen ovale

Vagus nerve (Ⅹ) components of fibers GVE fibers: originate from dorsal nucleus of vagus nerve, synapse in parasympathetic ganglion, short postganglionic fibers innervate cardiac muscles, smooth muscles and glands of viscera SVE fibers: originate from ambiguus, to muscles of pharynx and larynx GVA fibers: carry impulse from viscera in neck, thoracic and abdominal cavity to nucleus of solitary tract GSA fiber: sensation from auricle, external acoustic meatus and cerebral dura mater