NEUROANATOMY
AND
NEUROPHYSIOLOGY
STUDY GUIDE
Neuroanatomy Learning Objectives
THE SPINAL CORD
The Gross Structure of the Spinal Cord in Situ
Lies within vertebral canal formed by foramina of vertebral column.
Extends from medulla oblongata (lower half of brainstem).
Spinal cord begins at occipital bone and ends between 1st and 2nd lumbar vertebrae.
The diameter of the spinal cord varies as follows (thickest to thinnest):
1. Cervical. The cervical enlargement extends from C3-T2. It corresponds with the brachial plexus nerves,
which innervate upper limb and 6th pair of cervical nerves.
2. Thoracic
3. Lumbar (note lumbar cord basically consists of the lumbar enlargement, which is thicker than thoracic
cord). It extends from T11-L1, below which it tapers rapidly into conus medullaris. It corresponds to
lumbosacral plexus nerves, which innervate lower limb.
The enlargements are where sensory and motor neurons enter and exit.
The spinal cord is divided into segments (31 spinal segments based on origins of spinal nerves):
1. There are 33 spinal cord nerve segments. Axons in CNS are grouped into tracts (not nuclei).
a. Cervical (C3-C8):
8 segments 8 pairs of cervical nerves (excluding C1 and C2. C1 spinal nerves exit column
between occiput and C1 vertebra. C2 nerves exit between posterior arch of C1 vertebra and
lamina of C2 vertebra).
b. Thoracic (T1-T12):
12 segments 12 pairs of thoracic nerves.
c. Lumbar (L1-L5):
5 segments 5 pairs of lumbar nerves.
d. Sacral (S1-S5):
5 segments 5 pairs of cranial nerves.
e. Coccygeal:
3 segments 3 segments join to form 1 segment 1 pair of nerves (exit through sacral
hiatus).
2. Motor nerve rootlets branch out of R. and L. ventro-lateral sulci.
3. Sensory nerve rootlets branch out of R. and L. dorsal lateral sulci.
4. Rootlets form nerve roots and are part of peripheral nervous system.
2 Ventral (motor) + 2 dorsal (sensory) roots= spinal nerve (one on each side of cord).
Spinal nerves (except C1 and C2) form inside and exit through inter-vertebral foramen below corresponding
vertebra.
Spinal nerves:
1. Upper part of vertebral column: Spinal nerves exit directly from cord.
2. Lower part of vertebral column: Spinal nerves pass further down column before exiting.
Terminal portion of cord is called conus medullaris. The pia mater continues as an extension called the filum
terminale, which anchors cord to the coccyx.
The cauda equina is a dangling collection of nerve roots in the vertebral column that continue to travel through
the vertebral column below the conus medullaris.
The cauda equina forms because the spinal cord stops growing in length at ~4yo, even though the
vertebral column continues to lengthen until adulthood. This results in the fact that sacral spinal
nerves actually originate in upper lumbar region.
Ganglia and Roots:
Each segment of the spinal cord is associated with a pair of ganglia, called dorsal root ganglia, which are situated
just outside spinal cord.
Dorsal root ganglia contain cell bodies of sensory neurons. Axons of these sensory neurons travel
into the spinal cord via the dorsal roots.
Ventral roots consist of axons from motor neurons, which bring information to periphery from cell
bodies in CNS.
Grey and White Matter of the Spinal Cord
The Gross Structure of the Vasculature of the Spinal Cord
Three arteries run longitudinally along the spinal cord:
1. One anterior (ventral) artery
2. Two posterior (dorsal) arteries
Spinal arteries arise from the segmental or root (radicular) arteries that follow dorsal and ventral spinal
roots. They interconnect in the pial plexus which then supplies the deep tissue of the spinal cord.
The other connections to the spinal arterial supply are:
1. Vertebral artery (cervical region)
2. Intercostal arteries (thoracic region)
3. Lumbar arteries (lumbar region)
4. Lateral sacral artery (sacral region)
Venous drainage of the spinal cord occurs from veins running parallel with the dorsal and ventral spinal
arteries and then into the large and complex epidural venous network.
The Internal Structure of the Spinal Cord
Internally, the spinal cord consists of: 1. White matter: Tracts of myelinated nerve fibres.
Lies around outside of grey matter.
Is divided into dorsal (posterior), lateral and ventral (anterior) funiculi.
The white matter is located outside of the grey matter and consists of myelinated motor
and sensory axons. Columns of white matter carry information up or down the cord.
2. Grey matter: Nerve cell bodies and their neuropil.
Lies centrally in the spinal cord.
In cross section looks like an H or a butterfly.
Contains a central canal which is continuous with ventricular system of brain.
The grey matter consists of interneurons and motor neurons. It also consists of
neuroglia cells and unmyelinated axons. Projections of the grey matter (wings) are
called horns. The grey horns and grey commissure form the “grey H.”
Neurons of the Spinal Cord
The Dorsal Roots of the Spinal Cord
Bear the dorsal root ganglia (sensory).
The Ventral Roots of the Spinal Cord:
1. Somatic motor fibres arise from final motor neurons in ventral horns striated muscle.
2. Autonomic preganglionic fibres arise from spinal preganglionic neurons. They are in the
intermediolateral columns (below) and project to final motor neurons in peripheral autonomic
ganglia:
a. Thoracic and upper lumbar cord (sympathetic).
b. Sacral cord (parasympathetic).
3. Paravertebral sympathetic chain ganglia are linked to the ventral roots by communicating
rami.
Lateral Horn
The lateral horn is found at thoracic, upper lumbar and sacral levels, which contain autonomic
preganglionic neurons.
Descending [upper] motor tracts of the WHITE MATTER (all end in various regions of ventral horns)
1. Cortico-spinal (pyramidal) Tract
a. Crossed = lateral funiculus.
b. Uncrossed = ventral funiculus.
2. Extra-pyramidal Tracts
a. Rubrospinal = descends in lateral funiculus
Small and rudimentary. Responsible for large muscle movement and fine motor
control.
b. Medullary Reticulospinal = descends in ventral/lateral funiculus
Excites anti-gravity extensor muscles.
The fibres of this tract arise from caudal pontine reticular nucleus and the oral
pontine reticular nucleus.
Fibres of this tract project to interneurons of lamina VII and VIII of cord.
c. Pontine (lateral) reticulospinal = descends in ventral funiculus
Inhibits excitatory axial extensor muscles of movement.
The fibres of this tract arise from the medullary reticular formation, mostly from the
gigantocellular nucleus, and descend the length of the cord in the anterior part of the
lateral column.
This tract terminates in the grey spinal laminae.
d. Vestibulospinal = descends in ventral funiculus
Maintain balance and posture of body and head based on information from the inner
ear (via vestibulocochlear nerve).
The fibres of this tract arise from the lateral vestibular nucleus.
This tract terminates at the interneurons of lamina VII and VIII.
Ascending [lower] sensory tracts of the WHITE MATTER (via the dorsal horns)
1. Fasciculus gracilis (carries information from below T6) = Ascends in medial part of dorsal funiculus
Bundle of axon fibres in posterior column of cord.
Carries proprioceptive information from middle thoracic and lower limbs of the body to the brain
stem.
Also carries deep touch, vibrational and visceral pain sensations to the brain stem.
2. Fasciculus cuneatus (carries information from T6 and up) = Ascends in lateral part of dorsal funiculus
Nerves running in posterior column of cord.
Sensation from spinal nerves in C1 and T6 dermatomes.
Carries fine touch, fine pressure, vibration and proprioceptive information.
Carries sensation to the brain stem.
3. Spinothalamic tract = Ascends in ventral and lateral funiculi
Transmits pain, temperature, itch and crude touch information to thalamus.
This pathway decussates at spinal cord level, not the brainstem.
There are two main parts of this tract:
a. Lateral tract: Pain and temperature.
b. Anterior (ventral) tract: Crude touch.
4. Dorsal spinocerebellar tract = Ascends in dorsal part of lateral funiculus
Transmits proprioceptive information from muscles to cerebellum.
This tract runs in parallel with ventral tract.
Transmits information from ipsilateral caudal aspect of the body and legs.
5. Ventral spinocereballar tract = Ascends in ventral part of lateral funiculus
Transmits proprioceptive information from muscles to cerebellum.
Transmits information from ipsilateral caudal aspect of body and legs.
The Relative Sizes of the Spinal Fibre Tract Varies with Spinal Level
Spinal Level Grey Matter White Matter
Sacral Dorsal horn prominent.
Lateral horn prominent.
Ventral horn large.
Small
Lumbar Dorsal horn prominent.
Lateral horn small/absent.
Ventral horn large.
Large
Thoracic Dorsal horn slender.
Lateral horn small.
Ventral horn modest.
Large
Cervical Dorsal horn slender.
Lateral horn absent.
Ventral horn large.
Large (especially lateral and dorsal)
The various sizes in the table above vary in accordance with the number of nerves that coverage on that area.
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The Gross Structure of the Meninges
The meninges consists of three principal layers and enclose a space containing the CSF (superficial to deep):
1. Dura
2. Arachnoid
3. Pia
The epidural space is external to the dura and carries the epidural veins of the spinal cord.
The CSF itself is in the subarachnoid space.
The spinal cord is suspended in the dural sheath by the denticulate ligaments that run from the inner surface of
the dura between the dorsal and ventral rootlets.
Other Aspects of the Spinal Cord
Be able to identify:
Dorsal sulcus
Ventral Medial Fissure
Conus Medullaris (tapering caudal end of spinal cord)
Filum Terminale (pial extension beyond spinal cord)
Cauda Equina (spinal nerves arising caudal to L2)
THE BRAIN
The Major Divisions of the Brain
Major functions of the brain have different embryological origins and different levels of function.
The brain (excepting the cerebral cortex, which is highly homogenous) can be divided into a series of major
division, each of which has a characteristic set of functions. Be able to identify:
PRIMARY DIVISION SECONDARY DIVISION MAIN STRUCTURE
Prosencephalon (forebrain) Telencephalon
Diencephalon
Cerebral hemisphere
Thalamus, hypothalamus
Mesencephalon (midbrain) Mesencephalon Midbrain
Rhombencephalon (hindbrain) Metencephalon
Myelencephalon
Pons, cerebellum
Medulla oblongata
The midbrain + hindbrain = brain stem
The Cortex
You can identify parts of the cortex by anatomical or functional criteria.
The major anatomical areas of the cortex are known as loves, the names of which reflect their location.
Be able to identify:
Frontal lobe
Temporal lobe
Parietal lobe
Occipital lobe
The two hemispheres of the brain are joined by a vast tract of nerve fibres, most of which are myelinated, known
as the corpus callosum. You can see it in sagittal sections.
The Landmarks of the Cortex
The surface of the cortex is folded into ridges (gyri) and fissures (sulci) that are more or less constant between
individuals.
STRUCTURE 1 SEPARATION STRUCTURE 2
Frontal lobe Lateral fissure (or sulcus) Temporal lobe
Frontal lobe Central sulcus Parietal lobe
Parietal lobes Separated on medial side of cerebral hemispheres by parieto-occipital fissure (or sulcus)
Occipital lobe
Be able to identify on whole brains, sagittal sections, cross-sections (real brains, CT and MRI):
Deep within the lateral fissure is a region of the cortex known as the insula
Cingulate gyrus
Corpus callosum
Parahippocampal gyrus
Precentral gyrus
Postcentral gyrus
Superior, middle and inferior gyri of frontal lobe
Superior, middle and inferior gyri of temporal lobe
Lobules of parietal lobe (superior and inferior lobe, divided by intraparietal sulcus)
The Diencephalic part of the Forebrain- the Thalamus (inner room) and Hypothalamus
Thalamus + hypothalamus = lateral wall of 3rd ventricle inferior to corpus callosum.
Pineal gland (circadian rhythms).
Thalamic nuclei have connections with cerebral cortex, cerebellum and spinal cord. There is a topographic
relationship between the thalamus and cerebral cortex.
Y-shaped internal medullary lamina divides thalamus into lateral, anterior and medial nuclear groups.
All sensory input (except olfaction) to the cortex is first relayed through thalamus.
Lateral geniculate body (visual system).
Medial geniculate body (auditory system).
Hypothalamus (immediately superior to optic chiasm).
Hypothalamic motor outputs to posterior and anterior pituitary.
Links to brainstem.
Links to cortical structures: amygdala, anterior cingulate and insula (visceral function, emotion, reward etc.)
The Midbrain
Tectum (dorsal surface).
Tegmentum (ventral surface).
Cerebral aqueduct.
Periaqueductal grey (autonomic function and sensory processing).
Superior and inferior colliculi on dorsal surface (visual and auditory processing respectively).
Corticospinal fibre tract (main motor output from cortex to spinal cord and fine motor control).
Corticobulbar fibre tract (motor cortex to brainstem areas involved in movement, balance and orientation).
Corticopontine fibres, which terminate in pontine nuclei (in pons) that in turn project to cerebellum.
Deep to fibre tracts is the substantia nigra.
Deep to substantia nigra is the red nucleus (source of rubrospinal tract).
Be able to identify all these structure on whole brains on in brain sections.
The Hindbrain- pons and medulla oblongata)
Main external feature of pons are cerebellar peduncles (superior, middle and inferior pairs) on dorsum.
Peduncles connect brainstem and cerebellum.
Dorsal pons forms floor of 4th ventricle.
Motor nuclei of abducens, facial and trigeminal nerves beneath floor of 4th ventricle.
Most of pons is fibres connecting with cerebellum.
Fasciculus gracilis -- sensory information gracilis nucleus.
Fasciculus cuneatus -- sensory information cuneatus nucleus.
Trigeminal sensory nucleus.
Pyramids, which contain corticospinal (pyramidal) tract.
Decussation of pyramidal tract.
The Olive contains inferior olivary nucleus (connects to cerebellum).
At the level of the Olive:
Lateral and medial vestibular nuclei
Nucleus tractus solitaries
Dorsal motor nucleus of vagus
Hypoglossal nucleus
Cerebellum
Involved with balance, coordination and learning.
Vermis (muscle tone and position).
Two lobes/hemispheres (coordination of muscle movement, trajectory, speed and force).
Surface of the cerebellum folia (cerebellar gyri)
Primary fissure separates anterior and posterior lobe.
Deep surface of primary fissure flocculus and node (together form flocculonodular lobe) balance.
Cerebellum connected to brain stem and midbrain by cerebellar peduncles.
The Cranial Nerves
Refer to attached document.
The Meninges (out to in)
1. Dura mater tough outer covering
2. Arachnoid mater soft translucent membrane underlying dura
3. Pia mater thin vascular membrane adherent to brain surface
The arachnoid and pia is the subarachnoid space, which is filled with CSF.
Subarachnoid cisterns (enlargement of subarachnoid space):
Cisterna magna
Interpeduncular cistern
Two reflections of the dura partially divide cranial cavity and provide paths for major cerebral sinuses:
Falx cerebri (between cerebral hemispheres) superior sagittal sinus
Tentorium cerebelli (between cerebral hemispheres and cerebellum) transverse sinus
Be able to identify:
Meninges on brains and sagittal heads
Subarachnoid space and main cisterns
Relation between dura and bones of skull
What happens to dura and the points where cranial nerves exit/enter skull
The Ventricles and CSF
CSF flows through:
Subarachnoid space
Ventricular system
CSF is made by choroid plexus.
Choroid plexus lines parts of:
Lateral ventricle
Third ventricle
Fourth ventricle
CSF is returned to circulation via arachnoid villi (lines superior sagittal sinus).
There are four ventricles:
1. Right lateral ventricle
2. Left lateral ventricle
3. Third ventricle
4. Fourth ventricle
The ventricles:
Are interconnected
Connect with the central canal of spinal cord
Connect with subarachnoid space (via foramina in 4th ventricle)
Foramina of the 4th ventricle:
1. Median aperture (foramen of Magendie) Cisterna magna
2. 2x lateral apertures (foramina of Luschka) Cerebellopontine angle
Be able to identify on models and sagittal sections:
Ventricles and interconnections
Relations of ventricles to subarachnoid spaces and cisterns
Relations of ventricles to major structures of the brain
Choroid plexus
Getting Blood to and from the Brain
Internal carotid and vertebral arteries supply blood to brain.
A small amount of blood gets to meninges via middle meningeal artery, which is the 3rd branch of the 1st part of
the maxillary artery, which is a branch of the external carotid artery.
The internal carotid feeds into anterior and middle cerebral arteries, which supply major areas of the brain.
The internal carotid and middle cerebral arteries also feed into:
ARTERY BRANCHES SUPPLIES
Hypophyseal artery Branch of internal carotid
Superior
Inferior
Pars tuberalis, infundibulum of pituitary and median eminence. Posterior pituitary.
Ophthalmic artery Branch of internal carotid artery
Internal carotid orbit
Central retinal
Lacrimal
Posterior ciliary
Muscular branches
Supraorbital
Ethmoidal
Medial palpebral
Terminal
Inner layers of retina. Lacrimal gland, eyelids. Posterior uveal tract. Extraocular muscles. Muscles and skin of forehead. Meninges. Eyelids. Forehead and nose.
Anterior choroidal artery Branch of internal carotid artery
None. Telecephalon, diencephalon and mesencephalon.
Posterior communicating artery Connections to internal carotid via middle cerebral artery and anterior cerebral artery. Posteriorly communicates with posterior cerebral artery.
None. Part of structure of Circle of Willis.
Vertebral arteries:
ARTERY BRANCHES SUPPLIES
Posterior inferior cerebellar Anterior medullary segment
Lateral medullary segment
Supratonsillar segment
Posteronferior cerebellum
Anterior inferior cerebellar Internal auditory
Lateral branch
Medial branch
Anteroinferior cerebellum
Labyrinthine (aka. auditory artery) Anterior vestibular
Common cochlear proper & vestibulochochlear
Ear
Superior cerebellar Perforating branches
Lateral (marginal) branch
Hemispheric branches
Superior vermian
Superior cerebellum
Posterior cerebral Posterior communicating
Medial posterior choroidal
Lateral posterior choroidal
Perforators
Temporal branches
Lateral occipital
Medial occipital
Splenial
Occipital lobes and posteromedial temporal lobes
Be able to identify all branches and aspects of the Circle of Willis.
What is the advantage in having a vascular circle at the base of the brain?
One advantage to a circle is that there are redundancies in circulation. If one vessel is blocked, the brain is
still perfused.
At the base of the brain, the circle has the greatest and most immediate access to the most parts of the
brain.
Dural venous sinuses:
SINUS DRAINS TO
Inferior sagittal Straight sinus
Superior sagittal Becomes right transverse
Straight Becomes left transverse
Transverse Sigmoid
Sigmoid Internal jugular
Cavernous Superior and inferior petrosal Internal jugular vein
Dural venous sinuses are venous channels found between layers of dura mater. They:
Receive blood from internal and external veins of the brain.
Receive CSF from subarachnoid space.
Ultimately empty into internal jugular vein.
Clinical relevance of sinuses:
Damage to dura mater may cause a thrombosis in dural sinuses haemorrhagic infarction
Cavernous sinus is:
Traversed by internal carotid artery
Surrounded by CN 3, 4, 5 and 6
Important because: Thrombosis in cavernous sinus can affect CN 3, 4, 5 and 6 resulting in symptoms
related to those nerves.
Dural venous sinus:
Drain into extracranial veins via emissary veins.
Emissary veins have no valves, so pus can flow into skull through them and they are therefore a possible
route for extracranial infection to enter the skull.
One emissary vein communicates from outside skull through sphenoidal emissary foramen inferior to the
zygomatic arch with the cavernous sinus on the inside of the skull. This is an important route for spread of
infection because CN 2, 4, V1, V2 and 6 and internal carotid pass through cavernous sinus. Infection or
inflammation in the cavernous sinus can damage any of the cranial nerves that pass through it, or
meningitis. Rupture of the emissary veins will result in subdural haematoma.
THE BRAIN II
The Major Areas of the Cortex Involved in Motor Activity
FUNCTIONAL REGION ANATOMICAL STRUCTURE
Primary motor cortex Precentral gyrus
Supplementary motor cortex Superior gyrus of frontal lobe, rostral to precentral gyrus
Premotor cortex Middle gyrus of frontal lobe, rostral to precentral gyrus
Broca’s area (speech motor area) Caudal part of inferior gyrus of frontal lobe, adjacent to lateral fissure
Frontal eye field (eye movements) Middle region of middle gyrus of frontal lobe
Somatosensory cortex - Awareness of body position, joint angles, muscle force and touch etc.
Postcentral gyrus
Parietal association cortex - Awareness of contralateral body, knowledge
of object shapes, personal space etc.
Superior parietal lobe
Hippocampus - Memory, spatial/temporal maps, emotional
aspect of behaviour
Medial aspect of temporal lobe, deep to Parahippocampal gyrus
The Basal Ganglia and Corpus Striatum
Be able to identify all parts of the basal ganglia, corpus striatum and amygdala.
Inter-hemispheric Connections
On sagittal sections be able to identify:
Corpus callosum
Anterior commissure (information between temporal lobes)
Association fibres connect various ipsilateral regions of the cortex. Be able to identify:
Superior longitudinal fasciculus
Inferior longitudinal fasciculus
Cingulum (“girdle”)
Connections between Cortex and Subcortical Structures
These connections are known as projection fibres.
Are input/output between cortex and thalamus, striatum, brainstem and spinal cord etc.
These projection fibres are divided into:
Corticospinal tract
Corticobulbar tract These fibres are distributed radially as corona radiata,
Thalamocortical tract which converge towards brainstem.
As fibres of corona radiate converge towards brain stem, they form the internal capsule.
The anterior limb of internal capsule contains connections between thalamus and prefrontal cortex.
The posterior limb of internal capsule contains:
Corticobulbar motor tracts
Corticospinal motor tracts
Thalamus and somatosensory cortex connections
Thalamus and motor areas of frontal lobe connections
THE SKULL
Gross Anatomy of the Skull
Looking at the base of skull you can see three main areas:
Anterior fossae
Middle fossae
Posterior cranial fossae
The floor of each fossa is traversed by foramina transmitting cranial nerves and/or blood vessels. Be able to
identify:
THE ANTERIOR CRANIAL FOSSA OF THE SKULL
FORAMINA CRANIAL NERVE/S BLOOD VESSLES
Cribriform plate Olfactory nerves
THE MIDDLE CRANIAL FOSSA OF THE SKULL
FORAMINA CRANIAL NERVE/S BLOOD VESSLES
Optic canal Optic nerve
Superior orbital fissure Oculomotor nerve
Trochlear nerve
Abducens nerve
Ophthalmic division of trigeminal nerve
Foramen rotundum Maxillary division of trigeminal nerve
Foramen ovale Mandibular division of trigeminal nerve
Foramen lacerum Internal carotid on floor
Foramen spinosum Middle meningeal Note hypophyseal fossa in which pituitary lies.
THE POSTERIOR CRANIAL FOSSA OF THE SKULL
FORAMINA CRANIAL NERVE/S BLOOD VESSLES
Foramen magnum Spinal root of accessory nerve
Spinal cord
Vertebral arteries
Hypoglossal canal Hypoglossal nerve
Jugular foramen Glossopharyngeal nerve
Vagus nerve
Accessory nerve
Internal jugular vein
Internal auditory meatus Vestibulocochlear nerve
Facial nerve
OTHER
Extraocular eye muscles.
The Auditory System
The Cranial Nerves
The cranial nerves emerge directly
from the brain, in contrast to spinal
nerves, which emerge from
segments of the spinal cord. In
humans, there are TWELVE
PAIRS of cranial nerves. The
FIRST AND SECOND emerge
from the cerebrum, the
REMAINING TEN PAIRS
emerge from the brainstem.
Mnemonic for the nerves
Oh, Oh, Oh, To Touch And Feel
Vagina, God Vaginas Are Hot.
Mnemonic for the type of nerve
S= Sensory, M= Motor and B= Both (sensory + motor)
Some Say Money Matters, But My Brother Says Big Boobs Matter More.
Mnemonic for the foramina
C= Cribriform plate (Olfactory), O= Optic canal, S= Superior orbital fissure (Oculomotor), S= superior orbital fissure
(Trochlear), S= Superior orbital fissure (Trigeminal – Ophthalmic), R= Foramen Rotundum (Trigeminal – Maxillary),
O= Foramen Ovale (Trigminal – Mandibular), S= Superior orbital fissure (Abducens), I= Internal acoustic meatus (Facial),
I= Internal acoustic meatus (Vestibulocochlear), J= Jugular foramen (Glossopharyngeal), J= Jugular foramen (Vagus),
J= Jugular foramen (Accessory), H= Hypoglossal canal (Hypoglossal).
Carl Only Swims South. Silly Roger Only Swims In Incredible Jacuzzis. Jane Just Hitchhikes.
Figure 1 The Cranial Nerves and their Distributions.
Cranial
Nerve
Foramen Branches Type of
Impulse
Nucleus
Name
Nucleus
Location
Symptom/Signs of
Damage
Function
Olfactory (CNI)
Telencephalon
Skull: Cribriform
Plate
Olfactory
Filaments
Special Sensory
(afferent)
Anterior
olfactory
Olfactory
tract
Anosmia Smell and nasal
mucosa.
Optic (CNII)
Diencephalon
Skull: Optic
Foramen
None Special Sensory
(afferent)
Lateral
geniculate
nucleus
Thalamus Blindness Vision and retina.
Oculomotor
(CNIII)
Anterior Aspect
of Midbrain
Skull: Superior
Orbital Fissure
Superior and
Inferior
Divisions
General Motor
(efferent)
Parasympathetic
Motor
Oculomotor
Edinger-
Westphal
Midbrain
Midbrain
Eye deviates down & out
Loss of
pupillary/accommodation
reflexes
Eye movement
(elevation and
adduction)
Trochlear
(CNIV)
Dorsal Aspect of
Midbrain
Skull: Superior
Orbital Fissure
Muscular
Branches
Motor (efferent) Trochlear Midbrain Diplopia, lateral
deviation of eye
Eye movement
(Superior oblique
muscle
depression of
adducted eye)
Cranial
Nerve
Foramen Branches Type of
Impulse
Nucleus
Name
Nucleus
Location
Symptom/Signs of
Damage
Function
Trigeminal
(CNV)
Pons
Skull: Superior
Orbital Fissure
Meningeal,
Frontal, Lacrimal
and Nasocilliary
General Motor
(efferent)
General Sensory
(afferent)
Principal
Spinal
Mesencephalic
Motor
Pons
Medulla
Pons/midbrain
Pons
Facial aneasthesia
Loss of pain sensation
Insignificant
Weakness/loss of mastication
Sensation from dura,
nasal mucosa and
beneath eye, side of
nose, cheek, lip, upper
teeth, hard palate and
mastication
Ophthalmic
(CNV1)
Skull: Superior
Orbital Fissure
Other: Supraorbital
Foramen, Anterior
and Posterior
Ethmoidal
Foramina
Meningeal,
Frontal, Lacrimal
and Nasocilliary
General Sensory
(afferent)
Maxillary
(CNV2)
Skull: Foramen
Rotundum
Other: Inferior
Orbital Fissure,
Infraorbital
Foramen
Meningeal,
Infraorbital,
Posterior and
Anterior Superior
Alveolar Branches,
Zygmoatic, Sensory
Roots to
Pterygopalantine
Ganglion and
Greater and Lesser
Palantine
General Sensory
(afferent)
Mandibular
(CNV3)
Skull: Foramen
Ovale
Other: Mandibular
Foramen
Meningeal,
Auriculotemporal,
Buccal, Lingual
and Inferior
Alveolar
General Sensory
(afferent)
General Motor
(efferent)
Figure 2 Sensory branches of Trigeminal nerve.
Cranial
Nerve
Foramen Branches Type of
Impulse
Nucleus
Name
Nucleus
Location
Symptom/Signs
of Damage
Function
Abducens
(CNVI)
Anterior Margin
of Pons
Skull: Superior
Orbital Fissure
Muscular
Branches
General Motor
(efferent)
Abducens Pons Medial eye deviation
(lateral rectus)
Eye movement
(Abduction)
Facial (CNVII)
Pons
(cerebellopontine
angle) above olive
Skull: Internal
Auditory Meatus
Other: Facial Canal,
Hiatus of Facial
Canal, Stylomastoid
Foramen
Internal acoustic
canal facial canal
stylomastoid
foramen.
Greater Petrosal
Nerve, Chorda
Tympani
(Auricular
Branch), Facial
Branches and
Cervical
Branches
Special and
General Sensory
(afferent)
General and
Parasympathetic
Motor (efferent)
Motor
Solitary
Superior
salivatory
Pons
Pons
Pons
Paralysis of facial
nerve muscles
Loss of taste
(anterior 2/3rds of
tongue)
Dry mouth, loss of
lacrimation
Facial expresssion
Taste
Salivation, lacrimation
Vestibulocochlear
(CN VIII)
Lateral to CNVII
(cerebellopontine
angle)
Skull: Internal
Auditory Meatus via
internal acoustic
canal.
None General Sensory
(afferent)
Vestibular
Cochlear
Medulla
Medulla
Dysequilibrium,
Nystagmus
Hearing
Balance
Hearing
Glossopharyngeal
(CN IX)
Medulla
Skull: Jugular
Foramen
Muscular
Branches,
Auricular Branch,
Lingual Branch,
Branch to Carotid
Body and Sinus,
Tympanic Branch
and Lesser
Petrosal
General and
Special Sensory
(afferent)
General and
Parasympathetic
Motor (efferent)
Nucleus
ambiguus
Inferior
salivary
Solitary
Medulla
Medulla
Medulla
Loss of taste
(posterior 1/3rd
)
Insignificant
Loss of gag reflex
Taste
Salivation
Innervation of pharynx,
sensation from carotid
and aortic bodies and
carotid and aortic
sinuses.
Cranial
Nerve
Foramen Branches Type of
Impulse
Nucleus
Name
Nucleus
Location
Symptom/Signs
of Damage
Function
Vagus (X)
Posterolateral
Sulcus of Medulla
Skull: Jugular
Foramen
Palatopharyngeal
Branch, Superior
Laryngeal
Branch,
Recurrent
Laryngeal
Branch, Carotid
Sinus Nerve,
Cardiac,
Pulmonary,
Gastric, Renal,
Hepatic,
Pancreatic, Small
Intestine and
Large Intestine
Branches
Sensory
(afferent)
Motor (efferent)
Nucleus
ambiguus
Dorsal motor
vagal
Solitary
Medulla
Medulla
Medulla
Dysphagia &
hoarseness of voice
Insignificant
Loss of cough reflex
(larynx/pharynx),
loss of taste (hard
palate)
Swallowing & talking
(palatoglossus)
Cardiac, GI tract,
Respiration, taste,
sensation from carotid
and aortic bodies and
carotid and aortic
sinuses.
Cranial
Accessory (XI)
Spinal accessory
Cranial and
Spinal Roots
Skull: Jugular
Foramen
Other: Foramen
Magnum
Muscular
Branches
Motor (efferent) Nucleus
ambiguus
Spinal
accessory
Medulla
Cervical cord
Insignificant
Head
turning/shoulder
shrugging weakness
Pharynx/larynx muscles.
Cranial branch overlaps
with vagal functions.
Neck & shoulder
movement
Hypoglossal
(XII)
Medulla
Skull: Hypoglossal
Foramen via
hypoglossal canal
Muscular
Branches
General Motor
(efferent)
Hypoglossal Medulla Atrophy of tongue
muscles, deviation
on protrusion,
fasciculaations
Tongue movement,
except palatoglossus.
Trigeminal, glossopharyngeal and vagus derive from 1st, 2
nd, 3
rd and 4
th branchial arches.
Parasympathetic preganglionic pathways run with ciliary, glossopharyngeal and vagus nerves. In the head, the ganglia are associated with
branches of the trigeminal nerve.
GANGLION PREGANGLIONIC PATH LOCATION
Ciliary Oculomotor Ophthalmic branch of trigeminal
Pteryogopalatine Facial Maxillary branch of trigeminal
Submandibular Facial Mandibular branch of trigeminal
Otic Glossopharyngeal Mandibular branch of trigeminal
Vagal Vagus Associated with target organs
Anatomy of the Cranial Nerves
Figure 3 Olfactory Nerve (CN I) passing through
cribriform plate of ethmoid bone Figure 4 Optic Nerve (CN II). Figure 5 Oculomotor Nerve (CN III).
Figure 6 Trochlear Nerve (CN IV).
Figure 7 Trigeminal
Nerve and its branches
(CN V).
Anatomy of the Cranial Nerves
Figure 8 Abducens Nerve (CNVI). Figure 9 Facial Nerve (CNVII).
Figure 10 Vestibulocochlear Nerve (CN VIII)
Anatomy of the Cranial Nerves
Figure 11 Glossopharyngeal Nerve and branches (CN IX)
Figure 12 Vagus Nerve (CN X).
Anatomy of the Cranial Nerves
Figure 13 Accessory Nerve with Cranial (joins Vagus) and Spinal
branches. The cranial branch is often considered part of the
vagus, while the spinal branch is considered the accessory nerve
(CN XI) proper.
Figure 14 Hypoglossal Nerve (CN XII).
Anatomy of the Cranial Nerves
Anatomy of the Cranial Nerves (Inferior View)
LOCALISING
STROKE
LESIONS