Radiology Pt 1 - Cns

Front 1

Cranial nerves

Back 1

Olfactory - special sense of smell
Optic - special sense of vision
Oculomotor - most eye movements
Trochlea - laterally rotates/intorts the eye (superior oblique)
Trigeminal - face sensation, some motor (mastication)
Abducens - abducts eye (lateral rectus)
Facial - muscles of facial expression, taste (ant. 2/3rds tongue) and salivary/lacrimal secretions
Vestibulocochlear - inner ear: hearing, rotation and gravity senses
Glossopharyngeal - taste (post 1/3rd tongue), parotid secretions, stylopharyngeus motor
Vagus - laryngeal and pharyngeal muscles, parasympathetic to thorax and abdomen (to splenic flexure), taste from epiglottis. Vocal cords.
Accessory - SCM, trapezius
Hypoglossal - tongue muscles: swallowing and speech

Front 2

Olfactory nerve

Back 2

An outpouching of the brain rather than a true nerve

O: Anterior olfactory nucleus in the middle of the lateral olfactory tract along the gyrus rectus. The tract then runs to the piriform cortex.

I: The cribriform plate, to the upper nasal cavity, nasal septum and superior nasal concha via the cribriform foramina

A: Special sense of smell

R: The piriform cortex, which is made up of the uncus, amygdala and parahippocampal gyrus is involved in olfaction.

Front 3

Optic nerve

Back 3

The optic tract and radiation is complex. The optic 'nerve' is actually in the CNS, surrounded by meninges.

O: Retinal ganglion cells at the back of the eye (ie it runs inwards)

I: The nerves radiate back to the chiasm, decussating (~53% of fibres) and continuing on to terminate in the lateral geniculate nucleus, the pretectal nucleus (superior colliciulus) and the suprachiasmatic nucleus. The tract from the lateral geniculate body runs to the visual cortex.

A: Vision to lateral geniculate
Eye reflexes to pretectal
Diurnal regulation to suprachiasmatic

R:
OPTIC NERVE:
The optic nerve forms from the axons of ~1.2 million retinal ganglionic cells. It passes through the optic canal at the superomedial orbit, along the sulcus chiasmaticus of the sphenoid bone to the chiasm.
The fibres decussate, including sending fibres to the suprachiasmatic nucleus, which is the most infero anterior part of the hypothalamus just above the chiasm, and affects diurnal rhythm due to light exposure.

OPTIC TRACT:
The optic tract runs back from the chiasm, sending fibres to the lateral geniculate body (subthalamic) and superior colliculus. The tract continues from the lateral geniculate body to the visual cortex in the posterior occipital lobe.

SUPERIOR COLLICULUS:
In the region of the superior colliculus are the Edinger-Westphal nucleus which act to constrict, accomodate and converge. The nucleus is actually more anterior adjacent to the oculomotor nucleus. The motor outputs are largely through the oculomotor nerve.
The pretectal nuclei send fibres across the posterior commisure, which controls the consensual light reflex.
There are inputs from the inferior colliculus, carrying auditory information which is cross-referenced to direct visual attention.

VISUAL CORTEX:
The end of the optic tract. Due to the way light falls on the retina, the left visual cortex processes the right visual field and visa versa. The visual cortex is seperated into 5 regions (V1-V5).
V1 is called the primary visual cortex and is located in and around the calcerine fissure. This sends fibres ventrally and dorsally (called the ventral and dorsal streams).

The ventral stream, also called the "what" pathway is directed down the infero-lateral temporal lobe, and deals with object recognition.

The dorsal stream, or the 'where/how' pathway is directed up to the parietal lobe, dealing with location, motion and eye control of movement via saccades - eg fibres to the eyes and arms for reaching.

Front 4

Oculomotor nerve

Back 4

The first cranial nerve that is not fully invested in meninges (it retains some pia and arachnoid).

O: Oculomotor nuclei and Edinger-Westphal nuclei in the posterior midbrain at the level of the superior colliculus, just anterior to the aqueduct. The E-W nuclei are slightly more posterior, closer to the aqeduct, and slightly more lateral. The fibres pass forward and exit the midbrain anteriorly.

I: Through the superior orbital fissure to the muscles of eye movement

A: The superior branch supplies the superior rectus and levator palpabrae superioris (elevation, adduction, intorsion of globe and elevation of eyelid)
The inferior branch supplies the medial rectus, inferior rectus and inferior oblique (adduction - adduction, depression and extorsion - extorsion, elevation, adduction)
The inferior branch also gives a branch to the ciliary ganglion, which accomodates and constricts the pupil.

R:
Emerges from the midbrain anteriorly, passing between the superior cerebellar and posterior cerebral arteries. It pierces the dura lateral to the posterior clinoid process, passing between the borders of the tentorium cerebelli.

It passes through the cavernous sinus along the superior lateral wall. In the cavernous sinus it recieves small branches from the sympathetic plexus and the opthalmic division of the trigeminal nerve.

The oculomotor nerve divides into superior and inferior rami, which pass through the superior orbitial fissure between the heads of the lateral rectus.

Front 5

Trochlea nerve

Back 5

Supplies a single muscle, the superior oblique. It is the only nerve to exit the brainstem posteriorly. Also the only nerve other than the optic to decussate.

O: Adjacent to the aqueduct at the level of the inferior nucleus. These fibres decussate at the inferior colliculus.

I: Through the superior orbital fissure to the superior oblique muscle.

A: Innervates the superior oblique muscle - this muscle turns through the trochlea (a ligament) at the supero-medial portion of the globe and is directed back to the upper outer quadrant of the globe.
The actions are therefore abduction, depression and intorsion (not when the eye is abducted, as the tendon is loose)

R:
The nucleus is immediately below the nucleus of the oculomotor nerve, and sends fibres medial and posteriorly. These decussate in the inferior colliculus, and it exits just below the colliculus (ie posteriorly in the midbrain).

It passes around the quadrigeminal and ambient cisterns, to pass between the SCerebellarA and PCA, and pierces the dura adjacent to the posterior clinoid process.

It passes through the cavernous sinus between the 3 and 5(1) nerves on the lateral wall (mid-way up the wall).

From there it passes into the superior orbital fissure and to the superior oblique muscle.

Front 6

Trigeminal nerve

Back 6

The trigeminal nerve is the major nerve of facial sensation. It also controls the muscles of mastication. The largest cranial nerve

Has 3 main branches - opthalmic, maxillary, mandibular. Only the mandibular has motor fibres.

O:
The trigeminal sensory nuclei is a set of 3 nuclei, extending through the midbrain, pons and medulla.
These are:

spinal trigeminal nucleus - a long nucleus in the medulla running up to the main trigeminal nuclei in the pons. Transmits touch, pain and temperature from the ipsilateral face.

Main trigeminal nucleus in the pons, just inside the middle cerebellar peduncle. It recieves light touch from face and proprioception from jaw. Most sensation from here travels along the trigeminal lemniscus to the contralateral (it decussates) ventral posteriomedial (VPM) nucleus of the thalamus. Sensory input from the teeth and jaws is sent to the ipsilateral thalamus via dorsal trigeminal tracts.

Mesencephalic nuclei which is long and thin, running from the midbrain lateral to the aqueduct and the pons on the lateral edge of the floor of the 4th ventricle.
These nuclei connect to the motor nuclei of the 5th nerve and are involved in the automatic portions of chewing and swallowing, including the jaw jerk reflex.

Motor - the trigeminal motor nucleus: Medial to the main sensory nuclei
Muscles of mastication, tensor tympani, tensor veli palatini, mylohyoid and anteror digastric.

I:
The trigeminal nerve exits the lateral pons, and splits into the 3 branches:
opthalmic
maxillary
mandibular

The three nerves arise from the trigeminal ganglion in Meckel's cave, which is bounded by the tentorium superolaterally, the cavernous sinus superomedially, the clivus medially and the petrous bone apex inferolaterally.

The opthalmic division leaves Meckel's cave, entering the cavernous sinus (below CN3 and 4 on the lateral wall), then runs through the superior orbital fissure, before splitting into the 3 branches - lacrimal, frontal and nasociliary

The Mandibular division passes from Meckel's cave into the cavernous sinus (below V1 on the lateral wall) and then through foramen rotundum. From there it crosses the pterygopalatine fossa, turns lateralward across the maxilla and enters the orbit through the inferior orbital fissure. It passes down the inferior orbit, enters the infraorbital groove and exits the infraorbital foramen. It has many named branches which all supply sensation to the maxillary face, as well as the teeth and parts of the pharynx/nasopharynx.

The mandibular division exits Meckel's cave (the sensory root from the ganglion and the seperate motor root from the pons join here) and passes through the foramen ovale.
The mandibular division has many named branches which supply sensation and motor supply to the lower face.

A:
Opthalmic division - skin on the upper face, upper eyelid upwards.
Maxillary division - sensation over maxilla, maxillary teeth and upper nasopharynx
Mandibular division - sensation over mandible, mandibular teeth and inside of mouth.
Motor supply to muscles of mastication, anterior belly of digastric, tensor tympani, tensor veli palatini

Front 7

Parasympathetic ganglia of the head

Back 7

Mnemonics: (Its the) COPS G (run!)


CILIARY:
Located in the posterior orbit, controls pupillary reflexes.

A:
Parasympathetic:
Sphincter pupillae to constrict the pupil (miosis)
Ciliaris bends the lens (accomodation)

Sensory:
Sensation of cornea, ciliary body, iris

Sympathetic:
Vasodilators
Dilator pupillae (mydriasis)
Muscles of eyelid elevation (suprise!)

N: Contains parasympathetic, sympathetic and motor fibres.

Parasympathetics from oculomotor nerve (origin EW nucleus)
Sympathetics from internal carotid plexus (origin superior cervical ganglion)
Sensory from opthalmic divison of trigeminal


OTIC:
An oval ganglion immediately below the foramen ovale in the infratemporal fossa.

A: Sympathetic and parasympathetic fibres to the parotid gland via branches of the trigeminal nerve (mandibular division).

N: Recieves parasympathetic input from the gloosopharyngeal nerve via the lesser petrosal nerve. Sympathetic input from the superior cervical ganglion.

R: The otic ganglion has several structures pass through it, which do not synapse in it -
The nerve to tensor tympani and tensor veli palatini from the trigeminal nerve
The nerve to levator veli palatini from the facial nerve.


PTERYGOPALATINE
A triangular ganglia situated in the pterygopalatine fossa adjacent to the opening into the sphenopalatine foramen.

A:
Sensation to nasal mucosa and palate (mainly seperate spenopalatine branches in maxillary nerve, some go through ganglion)

Parasympathetics to secretory and vasodilator fibres of nose and upper oral cavity/nasopharynx.

Sympathetics to similar distribution.

N:
Sensory via maxillary nerve.

Parasympathetics via the greater petrosal nerve, which arises in the geniculate ganglion. This ganglion is supplied by the nervous intermedius of the facial nerve. The greater petrosal nerve is joined by the deep petrosal nerve to form the vidian nerve (nerve of the pterygoid canal) which enters the pterygopalatine ganglion.

Sympathetics via deep petrosal nerve, which arises from the superior cervical ganglion. The deep petrosal nerve joins the greater petrosal nerve to form the vidian nerve (nerve of the pterygoid canal) which enters the pterygopalatine ganglion.

R: The maxillary nerve crosses the pterygopalatine fossa just above the pterygopalatine ganglion. The other structure in the fossa is the terminal part of the maxillary artery.


SUBMANDIBULAR:
A small fusiform ganglion adjacent to the submandibular gland.

A: Submandibular and sublingual glands, secretory to oral mucosa.

N: Parasympathetics from the lingual nerve (trigeminal, mandibular branch) and chorda tympani (facial nerve).

Sympathetics from external carotid plexus, fibres travel along the facial nerve branches.

R: Above the deep portion of submandibular gland. On hyoglossus, just posterior to mylohyoid.


GENICULATE GANGLION
An L-shaped collection of fibres at the genu of the facial nerve as it exits the IAM

A: All functions of facial nerve including nervus intermedius pass through here -
muscles of expression - exit via the facial nerve proper
sensation and parasympathetics - exit anteriorly via the greater petrosal nerve.

N: Facial nerve (proper and nervus intermedius)

Front 8

Cervical sympathetic chain

Back 8

Sympathetic fibres ascend through the neck, arising from the cervical nerves. There are several communications, with the sphenopalatine ganglion

The ascending pathway is as follows -

Cervical nerve roots supply the Inferior (also called stellate, C7-T1), Middle (C5-C6) and Superior (C1-C4) cervical ganglia, which all communicate via the ascending pathway.

The ascending pathway then runs in a paravertebral distribution to the internal carotid plexus, on the lateral side of the carotid around the intracranial portion. It runs upward all the way to the circle of Willis, and is seen around the ACA, MCAs.

Below the cavernous sinus the carotid plexus gives off the deep petrosal (which joins the greater petrosal to form the vidian nerve, ending in the pterygopalatine ganglion) and several branches to the glossopharyngeal nerve via caroticotympanic nerves.

At the cavernous sinus the carotid plexus gives off branches to the 3rd, 4th, 6th and V1 nerves, and to the ciliary ganglion.

Front 9

Abducens nerve

Back 9

6th nerve, innervates the lateral rectus muscle - abducts the eye.

O: Abducens nucleus in the inferior pons, just anterior to the fourth ventricle, and superior to the ponto-medullary junction.

I: Goes through the superior orbital fissure and innervates the lateral rectus.

A: Abducts the eye.

R: Fibres pass downward through the pons lateral to the corticospinal tract.
They leave the anterior brainstem between the pons and medulla, medial to the facial nerve.
It runs upward towards the eye in the prepontine cistern, and pierces the dura mater along the clivus. It turns at the peak of the bone to run in the cavernous sinus alongside the ICA.
From here it passes through the superior orbital fissure to the lateral rectus.

Front 10

Facial nerve

Back 10

Mainly motor with some sensory and parasympathetic input. Multiple named parts. Controls facial expression, most of taste and other minor things.

O: The facial motor nucleus in the dorsal pons, just inferior and antero lateral to the 6th nerve nucleus. The fibres pass behind the 6th nucleus, wrap around it and pass forward to exit the brainstem lateral to the abducent nerve in the pontomedullary junction.

The nervus intermedius contains parasympathetic and sensory fibres.

The sensory cell bodies are located in the geniculate ganglion.

The parasympathetic cell bodies are in the superior salivary nucleus just dorsomedial to the facial nucleus.

The sense of taste (from the palate via the vidian nerve) is relayed to the solitary nucleus which is long and thin, running up the medulla medial to the spinal trigeminal nucleus

I: The motor portions give off branches:

The nerve to stapedius in the facial canal arises adjacent to the pyramidal emminence.

at the stylomastoid foramen -
the posterior auricular nerve to scalp muscles
the nerve to posterior digastric and stylohyoid.

In the parotid -
the 5 named branches
temporal
zygomatic
buccal
mandibular
cervical

The parasympathetic fibres are passed via -
the greater petrosal nerve from the geniculate ganglion to the pterygopalatine ganglion then to the lacrimal gland and paranasal sinuses. It also carries taste sensory fibres to the palate via the vidian nerve.

The chorda tympani arises from the nerve in the mastoid portion of the temporal bone, and supplies parasympathetics to the submandibular and sublingual glands, as well as taste to the anterior 2/3rds of the tongue. The chorda tympani crosses the middle ear, between the malleus and incus, on the medial neck of malleus. The nerve then passes through the petrotympanic fissure to exit the skull at the temperomandibular joint. It joins with the lingual branch of the mandibular nerve and runs to the submandibular ganglion. Fibres then run to the submandibular and sublingual glands (parasympathetic) as well as the anterior 2/3rds of the tongue.

Front 11

Vestibulocochlear nerve

Back 11

The nerve transmitting hearing and balance from the inner ear. Splits into vestibular and cochlear branchs in the IAM

O: The fibres enter the medulla at the inferior peduncle laterally. There are 2 nuclei

The cochlear nucleus -
Dorsolateral region at the junction of the pons and medulla, at the inferior peduncle (lateral edge)

Vestibular nucleus -
spans the pons and medulla in the floor of the 4th ventricle.

I: The bony labyrinth and cochlea of the inner ear

A: Vestibular - balance/gravity sense from the semicrcular canals
Cochlear - hearing

R:
The cochlear nerve arises in cell bodies in the cochlear ganglion (in the modiolus).

The vestibular nerve arises in the vestibular ganglion (Scarpa's) extending peripheral processes to the ampullae of the semicircular canals.

The nerves come run together through the internal acoustic meatus. The canal is divided into 4 quadrants by the crista falciformis horizontally and Bill's bar vertically. These quadrants transmit -
The facial nerve and nervus intermedius anterosuperiorly
The cochlear nerve anteroinferiory
The superior and inferior vestibular nerves posteriorly. The labyrinthine artery runs through the IAM also.

The ascending paths are as follows:

VESTIBULAR:
Position/balance sense from the vestibular nuclei ascends to the contralateral superior cerebellum, the tegmentum and to the oculomotor nucleus. Fibres also descend via the vestibulospinal tract to the anterior horn cells at many spinal levels. Together all these areas co-ordinate balance and movement.

COCHLEAR:
The fibres projecting from the cochlear nuclei run to superior olives bilaterally (ipsi and contralateral). Other fibres project to the contralateral lateral lemniscus and extend to the inferior colliculus. Finally some fibres bypass the inferior colliculus and extend directly to the medial geniculate body (acts as a relay station). Almost all projections are bilateral.

Fibres then extend to the superior temporal gyrus (near the posterior genu) which contains the primary auditory cortex. The auditory association cortex (in Wernicke's area) is also nearby.

Front 12

Glossopharyngeal nerve

Back 12

Mainly sensory, supplies 1 muscle (stylopharyngeus). Recieves taste from posterior tongue and supplies parasympathetic to the parotid.

O: The upper medulla, fibres to 3 nuclei
The nucleus ambiguus
The inferior salivatory nucleus
The solitary nucleus

The nucleus ambiguus is just dorsal to the inferior olivary nucleus in the upper medulla. It give origin to motor fibres from the stylopharyngeus (as well as the muscles of the vagus).

The inferior salivatory nucleus is likely within the upper medulla, above the nucleus ambiguus and below the superior salivatory nucleus.

The solitary nucleus runs through the upper medulla and lower pons medial to the spinal trigeminal nucleus.

I: Many end-points.

A:
Mainly sensory to the tonsils, pharynx and middle ear, supplies 1 muscle (stylopharyngeus). Recieves taste from posterior tongue and supplies parasympathetic to the parotid. Also recieves sensory fibres from carotid body.

R: Exiting the anterior medulla superiorly (anteromedial to the vagus) it passes down and laterally across the flocculus (of the cerebellum) to pass through the jugular foramen.

Just before the jugular foramen it runs adjacent to the opening of the cochlear aqueduct.

In the jugular foramen it passes between in IJV and ICA, and descends anterior to the ICA. It passes the stylopharyngeus (ie at the styloid process) and curves forward across that msucle, to the mouth, supplying the palatine tonsils, the mucous membranes, the base of the tongue and the mucous glands of the mouth.

There are 7 main branches -
Tympanic - runs from in the jugular foramen up through the tympanic canal to supply the sensation of the ear cavity. The fibres then merge with the inferior petrosal nerve to leave the base of skull and supply the parotid gland.
Stylopharyngeal - arises as nerve passes the muscle
Tonsillar -
Lingual -
Post tongue - all arise as the nerve runs to the mouth under hyoglossus.
Nerve to carotid sinus arises as descending nerve passes the ICA. This nerve communicates with the vagus.

Front 13

Vagus nerve

Back 13

Supplies muscles of the throat but also extends to supply parasympathetic to thorax and abdomen. Also recieves sensory information from the visceral organs.

O: Arises in the solitary nucleus (medial to the spinal trigeminal nucleus in the pons and medulla)
The motor nucleus of the vagus in the floor of the 4th ventricle in the posterior upper-mid medulla. It supplies parasympathetic to the thoracic and abdominal viscera, other than the heart.

The nucelus ambiguus which supplies parasympathetic to the heart, which is anterolateral to the vagus nucleus in the upper medulla.

Exits the medulla between the olivary nucleus and inferior cerebellar peduncle, on the anterolateral region.

I: To the muscles of the pharynx and larynx. It supplies parasympathetic fibres to the organs down to the end of the midgut (excluding adrenals).
It also recieves sensory input from these organs, in fact 80-90% of fibres in the vagus are afferent.

R: On leaving the medulla it extends down through the jugular foramen. It passes into the carotid sheath between the ICA and IJV (like CN9) and continues through the neck.

The right vagus gives off the recurrent laryngeal nerve (motor supply of the pharynx/larynx) at the right subclavian, which is curls around the subclavian and passes up the neck between trachea and oesophagus.

The left vagus gives off this branch in the mediastinum, curling around the aortic arch to the left of ligamentum arteriosum, and ascends as the right between oesophagus and trachea.

The left vagus passes along the outer border of the heart, and enters the abdomen as the anterior vagal trunk through the oesophageal hiatus.

The right vagus passes posterior to the SVC and forms the posterior vagal trunk, entering the abdomen through the oesophageal hiatus.

In the chest the vagus gives off cardiac, oesophageal and pulmonary branches/plexi

In the abdomen both trunks supplu coeliac and gastric branches, the anterior trunk also gives off a hepatic branch.

Front 14

Accessory nerve

Back 14

Has 2 parts - the cranial part which joins the vagus and is now largely considered part of the vagus, and the spinal part which arises from the cervical cord (ie not a true cranial nerve)

O: Arises in the lower medulla and upper cervical cord, in the nucleus ambiguus and spinal accessory nucleus.

I/A: SCM and trapezius

R:
The nucleus ambiguus is long, running from lower pons and through medulla. It is medial to the spinal trigeminal nucleus in the dorsal brainstem. This is the nucleus which supplies the part that connects with the vagus.

The spinal accessory nucleus sits in the cervical cord from C1-C5 in the lateral horn (most motor nerves arise in the anterior horn). The lateral horn appears continues with the nucleus ambiguus.

The rootlets exit at the spinal levels, pass upwards through the forament magnum and turn into the jugular foramen with CN9 and 10. The cranial portion descends from the nucleus ambiguus, briefly joining the spinal accessory, before branching off to join the vagus. In many people the cranial branch never joins the spinal branch.

After exiting the jugular foramen, the spinal accessory passes backwards and down, crossing the IJV in the anterior triangle. It passes anteriorly ~80% of the time, posteriorly ~20% of the time, and rarely pierces a variant bifid vein.
From here it passes down into the SCM and trapezius muscles.

Front 15

Hypoglossal nerve

Back 15

Supplies muscles of the tongue.

O:
The hypoglossal nucleus extends the length of the medulla close to the midline in the open portion of the medulla (seen as a raised area, the hypoglossal trigone).
In the closed medulla it lies slightly lateral to the midline, which is taken up by the gracile and cuneate nuclei.

The nerve arises from the anterior medulla in the preolivary sulcus, between the olive and the pyramid.

I/A: The tongue muscles apart from palatoglossus (CNX)

R: Passes from the medulla through the hypoglossal canal. It picks up a small branch from the C1 anterior ramus.

It then passes behind the vagus, between the ICA and IJV, and then passes deep to the posterior belly of digastric.

It extends to the submandibular region and enters the tongue.

Front 16

Frontal lobe - surface anatomy

Back 16

Borders:
Post: Central sulcus
Inferior: Lateral sulcus

Surfaces:

SUPEROLATERAL: 4 gyri

Precentral gyrus - Runs coronally. Primary motor cortex, has designated homuncular distribution, with leg superomedially and head inferolaterally. Inverted omega is hand area.

The remaining 3 gyri run longitudinally (sagitally), in front of the pre-central sulcus. The posterior elements of these are sometimes called the premotor cortex (although anatomic differentiation is difficult).

Superior frontal gyrus: Above superior frontal sulcus extending to midline. Involved in self-awareness in coordination with sensory system. There might be a 'laughter' area that intercepts sensory input and labels it 'funny'

Middle frontal gyrus. In between the superior and inferior frontal sulci, forms the bulk of the anterolateral brain. Has a lot of variable sulcation.

Inferior frontal gyrus is below inferior frontal sulcus, and extends to the lateral fissure. This area is implicated in inhibition and higher similar functions like risk aversion.

The gyrus is divided into multiple named areas, by the 2 rami of the anterior lateral fissure - the anterior ramus and ascending ramus, which arise together.

The pars opercularis is behind the ascending ramus, just anterior to the base of the precentral gyrus.
The pars triangularis is between the ascending and anterior rami.
Together the pars opercularis and triangularis contain broca's area (speech-language production area)

Below the anterior ramus is the pars orbitalis.

INFERIOR SURFACE:

The medial strip running sagitally is called the gyrus rectus and just lateral to this is the olfactory gyrus. These areas are overlayed by the olfactory bulb inferiorly.

Lateral to this is the orbital gyri, which are seperated by the H-shaped orbital sulcus. This divides the orbital gyri into anterior, posterior, medial and lateral elements.
The orbitiofrontal cortex is thought to play a large role in decision making and reward behaviour.

The frontopolar region is the most anterior part of the brain to the midline, and is poorly understood. It is extensive in humans, and may be related to storing tasks for future resumption - a work queue.

MEDIAL SURFACE:
The medial frontal lobe surface is made of 2 bands, inner and outer, that run around the radius of the lobe.

The inner band is the cingulate gyrus, which runs around the body and splenium of the corpus callosum (above the callosal sulcus), to the parahippocampal gyrus of the temporal lobe via the isthmus.

The outer band is seperated from the cingulate gyrus by the cingulate sulcus. The band is divided above the mid-corpus by a small ascending gyrus into the paracentral lobule (posteriorly) and the medial frontal gyrus (anteriorly).

The paracentral lobule is made up of frontal and parietal lobes, the anteior portion being frontal and involved in motor planning and sensory association.

The medial frontal gyrus runs forward to the polar region. This is thought to have a role in executive function.

Anteriorly the medial frontal gyrus curves around the frontal pole, turning down and dorsal and becomes the ventromedial cortex. This is involved in decision making, fear and risk, along with the orbitofrontal cortex.

The most inferoposterior section communicates with the cingulate gyrus, and is called the subcallosal area. It is connected to olfactory regions, and is also thought to play a role in mood and anxiety, being particularly rich in serotonin receptors. Deep brain stimulation for chronic depression is sometimes targetted here.


Function:
Overall the frontal lobe controls higher functions and motor functions.
The precentral is motor control, pre motor is motor planning and sensory integration, and everything in front is executive control -
things like:
inhibition/disinhibition
risk behaviour
decision making
sensory integration related to mood

Front 17

Temporal lobe - surface anatomy

Back 17

Borders:
Superior - lateral sulcus
Posterior - arbitrary line between parietooccipital sulcus and the preoccipital incisure

Surfaces:

LATERAL: 3 gyri run sagitally and caudally as the go forward

Superior, middle and inferior temporal gyri are layered on each other, seperated by the superior and inferior temporal sulci.

The superior temporal gyrus (on the dominant hemisphere) contains Wernicke's area posteriorly (at the tip of the lateral sulcus). Wernicke's controls understanding of written and spoken language.
Antero/inferior to this is the primary auditory cortex. Auditoy signals pass through here to become 'percieved'. Ie primary cortices all produce conscious awareness to stimuli, but reflex respose occurs without these areas.

The middle temporal gyrus is involved in face recognition, accessing the meaning of words and contemplating distances.

The inferior temporal gyrus is involved with representation of complex visual objects, such as shape recognition.

In addition, there are several small connections between the superior temporal gyrus and the adjacent frontal lobe (insula etc). These are called transverse temporal gyri, and communicate auditory information to other brain regions from the primary auditory cortex. There are usually 2, but can be single as well.

INFEROMEDIAL SURFACE:
This is formed of 2 main bands - the fusiform gyrus inferiorly and the parahippocampal gyrus superiorly, below the 3rd ventricle.

The fusiform gyrus can also be split into 2 gyri, the medial and lateral occipitotemporal gyri, divided by the occipitotemporal sulcus, which runs almost from temporal pole to occipital pole.
This region is involved in face, word, colour, number recognition and perception of emotions in others due to nonverbal cues.

The parahippocampal gyrus is involved in memory encoding and retrieval, as well as recognising broad background information such as social settings.

MEDIAL TEMPORAL LOBE
The medial temporal lobe is deep between the lateral and medial surfaces. It is really a deep structure rather than cerebrum, although the parahippocampal gyrus and dentate gyrus (superior to parahippocampal, below hippocampus) are considered part of it.

Function:
The temporal lobes are involved in sensory association (visual, auditory, probably olfactory) as well as memory formation and retrieval - makes sense as associations (like face recognition) are based around memory retrieval.

Front 18

Occipital lobe - surface anatomy

Back 18

Borders:
Anterior - The arbitrary line between the parieto-occipital sulcus and the preoccipital incisure.
Superior - The parieto-occipital sulcus.
Inferior - tentorium cerebelli

Surfaces:

LATERAL:
The lateral occipital sulcus runs anterosuperiorly from the peak of the occipital pole, and divides the outer surface into superior and inferior gyri. This area is variable and not well defined.

MEDIAL SURFACE:
The medial surface is split by the calcerine fissure, which arises at the occipital pole and runs forward to the splenium of the corpus callosum. It is joined by the parietooccipital fissure along the way.

The regions seperated by the calcerine fissure contain the primary visual cortex.

Above the calcerine fissure is the cuneus. Below is the lingual gyrus. The visual field maps inverted, so the superior brain recieves the inferior visual fields and visa versa.

The lingual gyrus (below the fissure) continues forward to the parahippocampal gyrus of the temporal lobe.

Function:
Primary visual cortex.
Dreams.
Visual associations and processing.

VISUAL OUTFLOW PATHS:
Outflow from the primary visual cortex is divided into 2 streams - the 'where' dorsal stream, which connects to the sensory and motor cortices and is involved in localising visual stimuli and coordinating movement with vision
and the 'what' ventral stream, to the temporal lobe, involved in recognition, conscious perception and memory.

Front 19

Parietal lobe - surface anatomy

Back 19

Boundaries:
Anterior - the central sulcus
Posterior - the parieto-occipital sulcus
Laterally - the sylvian fissure and an imaginary continuation

LATERAL SUFACE:
Most anteriorly is the post central gyrus running coronally along the vault. This is the primary somatosensory cortex.

Posterior to this is the postcentral sulcus. Behind that the entire region is called the posterior parietal cortex, which can be divided into superior and inferior parietal lobules. The sagital sulcus dividing these is the intraparietal sulcus. The function of the posterior parietal cortex is to combine inputs from auditory, visual and sensory sytems to help plan movement.

The lower portions of the inferior parietal lobule can be divided into 2 small areas that associate with the end of the superior temporal and middle temporal gyri. These are called the supramarginal gyrus anteriorly and the angular gyrus posteriorly.
These areas are involved in language, and because of their central location between all lobes, they are thought to be very involved in multi-modal processing like understanding metaphors and other abstractions. The angular gyrus is very large in humans compared to other apes.

The parietal portion of the operculum is the region of brain above the sylvian fissure that overlies the insular cortex. It mainly contains the lower primary sensory cortex.

MEDIAL SURFACE:
The medial surface is divided into anterior and posterior segments, the paracentral lobule (also part of the frontal lobe) and the precuneus posteriorly.
These are divided by the marginal sulcus.

Like the external posterior parietal lobe, the precuneus is involved with complex multisensory tasks - mental imagery, memory of multimodal events, attention focussing and consciousness.

The paracentral lobule is thought to contain parietal sensory inputs to the supplementary motor area within it anteriorly, which is involved in planning motor actions.

FUNCTION:
The primary sensory cortex maps the somatosensory inputs from the body on a homunculus, like the motor cortex. Feet are at the top, mouth and head at the bottom. The hand area and face areas are the largest.

The posterior parietal cortex processes combined modalities of information to plan movement as well as supply the temporal lobe for comprehension/perception

Front 20

Corpus callosum

Back 20

Location: Connects the cerebral hemispheres, located in the midline in the longitudinal fissure. Lies superior to the septum pellucidum, the commisural fibres and the third ventricle.

Parts:
Curved convex superiorly. The broadest posterior portion is the splenium, the long bulk is the body, and the anterior curve is the genu.
It retroverts under the genu to form the beak-like rostrum.

The fibres radiating out anteriorly from the genu are called the forceps minor, fromt he body are called the tapetum, and from the splenium are called the forceps major.

Front 21

Basal ganglia

Back 21

A collection of deep brain nuclei in the region of the 3rd and lateral ventricles.

PARTS:
The caudate nucleus - curved nucleus with a large head, tapering body and curving forward tail. It runs from the lateral wall of anterior horn, over/lateral to the body of lateral ventricle and superior to the inferior horn. It is associated with the inferior putamen at the tail.
Part of the limbic system.

The lentiform nucleus -
2 parts - Globus Pallidus and Putamen.
GP medial portion, more myelin content
Putamen is lateral component.
In between is the extramedullary lamina.

The thalamus -
Ovoid, largest basal ganglia. Extends from foramen of munro to quadrigeminal plate. Forms the lateral wall of the 3rd ventricle. Laterally bordered by internal capsule.
Has anterior, medial, lateral, pulvinar and geniculate groups. Thalami are joined by small (often absent) interthalamic mass.
The subthalamus is a small nucleus below the thalamus, and is involved (along with GP and substania nigra) in Parkinson's disease/ballismus. It lies suprolateral to red nucelus.

Front 22

Thalamus

Back 22

A deep central brain structure, the largest single structure in the diencephalon. It is the relay station of the brain.

Located along the 3rd ventricle, and communicating across the midline via the interthalamic mass the thalamus is made up of multiple regions

PARTS:
S Superior region - recieve neurons from the subiculum of the hippocampal formation. Gives branches out to mamillary bodies and cingulate cortex. Involved in emotion and memory.

M Medial region. The largest mass of the human thalamus. Connects strongly to the frontal cortex, as well as parts of the cingulate and insular cortices.

P Posterior/Pulvinar part
The posterior pole of the thalamus is called the pulvinar. Similar connections to the medial region (to and from the cortices).

B Basal region
Recieve spinothalamic tracts.

G Geniculate region (posterior base as 2 oval bodies)
The medial geniculate relays auditory signals via the inferior colliculus/superior olives.
The lateral geniculate relays visual signals from the chiasm to the optic radiation, and fibres to the superior colliculus (fibres related to eye reflexes)

L Lateral region
Misnamed, this is actually ventral in the thalamus. Contains multiple regions:

1 section from the spine, with multiple subdivisions.
Lemniscal regions VPL, VPM, VPO carry information from the lemnical tracts/gracilis and cuneate nuclei

1 from the posterior brainstem/cerebellum
Cerebellar nucleus VL/VIm recieves data from cerebellum and spinothalamics re movement.

And 2 from basal ganglia -
Pallidal region VO
Nigral region VA

Blood supply:
4 arteries
Polar artery of PCOM
Inferolateral arteries
Paramedian thalamic arteries
Posterior choroidal arteries

Front 23

Hypothalamus

Back 23

a

Front 24

Motor pathways

Back 24

a

Front 25

Sensory pathways

Back 25

a

Front 26

Parts of the CNS

Back 26

Rhombenchephalon (hindbrain) - medulla, pons and cerebellum

Mesencephalon (midbrain)

Diencephalon (lower forebrain) - thalamus, hypothalamus, basal ganglia

Telecephalon - Cortical brain

Front 27

Insular lobe

Back 27

Considered a seperate lobe, the insular is a small region abutting the sylvian fissure, made up of the long gyrus posteriorly, and 2-3 short gyri anteriorly.

The lobe is surrounded by the circular sulcus which seperates it from the other lobes.

Function: A central structure - it combines modalities to aid in formation of awareness, emotions related to stimuli (disgusting smell etc), homeostatic mechanisms and some motor functions.

Front 28

Limbic lobe

Back 28

The deep brain structures that are involved in memory and deep emotions, like fear and anger.

PARTS:
Cingulate gyrus, and just between it and the corpus, the supracallosal gyrus or indusium griseum
Dentate gyrus
Parahippocampal gyrus and its anterior hooked portion, the uncus. The uncus morphologically is actually part of the rhinencephalon (olfactory cortex)
Hippocampus
Amygdala
Fornices
Mamillary bodies

other inputs from - hypothalamus, thalamus and pituitary

The hippocampus itself Is a coronally orientated structre deep to the dentate gyrus. It curls medially, and passes inferiorly (like a knight shape in chess) and joins the subiculum, which in turn joins the parahippocampal gyrus. This entire folded structure really rests within the space between the dentate and parahippocampal gyri.

Function: Emotion, memory, spatial navigation.

Front 29

Choroid plexus

Back 29

The choroid is a layer of capillaries, lined with ependymal cells, that invests into the ventricles. It produces CSF.

Location:
The choroid exists in all of the ventricular system other than the aqueduct. It starts in the inferior horns of the lateral ventricles, continues into the inferior bodies and then through the interventricular foramen of munro. It passes into the superior portion of the 3rd ventricle.

The 4th ventricle has seperate choroid, as it does not pass through the aqueduct. It exists in the lower wall of the 4th ventricle, at the level of the lower cerebellum.

Parts: The tela chorioidea is the part in the inferior body of the lateral ventricles that arises from a triangular process of pia matter, the origin of blood vessels to the choroid. Supply comes from the superior cerebellar artery.

Front 30

White matter tracts

Back 30

Divided by type

ASSOCIATION - between cortical areas in one hemisphere

Cingulum - deep to cingulate gyrus, connects frontal, parietal and some temporal regions
Uncinate fasciculus - from the uncus back, connects the motor speech area to the temporal lobe
Longitudinal fasciculi - superior and inferior bundles. Superior is above cingulum and connects frontal lobe to all other areas
Inferior is below ventricles and connects occiptal and temporal
Occipitofrontal fasciculi - Superior and inferior - run around 3rd ventricle like a shell, and connect occipital to frontal lobes. Continues as the sagittal stratus which connects occipital to everywehere.

COMMISURAL - between the hemispheres
Corpus callosum
Anterior commisure - embedded in anterior wall of third ventricle to connect ant. perf substance, olfactory tract anteriorly and temporal lobes posteriorly
Posterior commisure - in posterior pineal lamina to connect midbrain, hypothalamus and thalamus

PROJECTION - between cortical and other CNS areas
Corona radiata - From internal capsule to all cortical areas
Internal capsule - narrowing of projection fibres from mid/hind brain and body. Anterior limb is pontine and thalamic projections. Genu is corticobulbar fibres. Posterior limb is corticospinal fibres, with upper limb anteriorly and lower limb posteriorly.
Sorticospinal tracts - Motor fibres from cortex to brainstem and spinal cord. Run to the cerebral peduncle and lateral fasciculus
Corticobulbar tract - Same as corticospinal but arising run to cranial nerve nuclei (motor)
Corticopontine - motor to pons
Corticothalamic - Connects all cortex to thalamus.

Front 31

Fornix

Back 31

Arises in the fibria of hippocampus, a white matter tract. Rises as crura bilaterally, anterior to splenium of corpus callosum.
Turns forward and medial as the commisural segment.
Commisural segments join below/attached to the septum pelucidum and form roof of 3rd ventricle.
The fornices turn downward and seperate again as the columns which run inferiorly to the mamillary bodies and anterior thalamus.

Part of the limbic system (emotion, memory)

Front 32

Amygdala

Back 32

Rests at the end of the caudate, medial to the uncus (anterior to the hippocampus).

Part of the limbic system (emotion, memory)

Front 33

Hippocampus

Back 33

Parts -
Confusing as the hippocampus proper (the ammon horn) lies coronally, and this horsehead curved architecture is the functional divisions. The bulk of the hippocampus grossly lies sagitally however.

Sagitally:
Head (pes hippocampus)
Body
Tail - extends back to the splenium of the corpus callosum and becomes the indusium griseum.

Coronally (Ammon horn):
Superior to inferio
Fimbria - the white matter tract that becomes the fornix
The dentate gyrus curls over as the ammon hern (which has 4 funtional zones) and then curls down to become the subiculum.
The white matter on the superior surface of the ammon horn is the alveus, which later (posteriorly) merges with the fibria to make the fornix.
The subiculum curls medially to join the parahippocampal gyrus.
2 other landmarks - The adjecent sulci on the inferior temporal lobe are the collateral sulcus proximally and the deeper occipitotemporal sulcus laterally.

Front 34

Pituitary gland

Back 34

Lies in the sella turcica, which is covered by the diaphragma sella. The diaphragm is pierced by the infundibulum (pituitary stalk). Also called the hypophysis.

Divided into Anterior and posterior regions.

Anterior pituitary: 80% of gland. Also called adenohypohysis, as it releases hormones like TSH, FSH, TSH, adrenocorticotropic hormone etc. Controlled by feedback loops and hypothalamus.

Posterior pituitary: 20% of gland.
Also called the neurohypophysis, as it is a neurological bundle from the hypothalamus. It does release hormone produced in the hypothalamus, namely oxytocin (lactation, labour) and vasopressin (water retention, blood pressure, aggression).

Blood supply: Superior and inferior hypophyseal arteries, portal venous blood from hypothalamus)

Variants:
Size variable, but should be <6mm in kids, 8mm in males and postmenopausal females, 10mm in young females and 12 in pregnant/lactating females.
Empty sella - Arachnoid/CSF protrudes into sella through diaphragm. Pituitary is flattened out, usually backwards. Normally asymptomatic.

Front 35

Pineal region

Back 35

In the posterior wall of the 3rd ventricle.

Contains -
PINEAL GLAND: Midline endocrine organ in the quadrigeminal cistern. Cennects to posterior commisure below and habenular commisure above by pineal stalks (sup/inf laminae).
The pineal gland produces melatonin and plays a role in sleep/wake, sexual development and some brain development.

MEDIAL POSTERIOR CHOROIDAL ARTERY:
Arise from PCA, supplies pineal gland as well as forming the choroid plexus of the 3rd ventricle. Runs superior to pineal gland (which has no blood brain barrier)

INTERNAL CEREBRAL VEIN:
Runs over the roof of the 3rd ventricle. The bilateral veins join posterior to the pineal gland to form the great cerebral vein of galen.

COMMISURES:
Posterior commisure below pineal gland connects dorsal thalamus, the superior colliculi and other midbrain structures. Some decussate here.
The habenular commisure (superior to pineal) connects hebnular, amygdaloid nuclei and the hippocampi.

OTHER:
The suprapineal recess and pineal recess of the 3rd ventricle are located adjacent.

The quadrigeminal plate is just below the pineal gland.

Front 36

Cranial fossae

Back 36

Anterior - bounded by the lesser wings of sphenoid. Houses frontal lobes

Middle - Bounded posteriorly by clivus and petrous crest. Houses temporal lobes

Posterior - bounded superiorly by tentorium cerebelli, houses cerebellum and brainstem.

The other fossa in the base of skull are the nasal cavity and the pterygopalatine fossa

Front 37

Midbrain

Back 37

PARTS:
ANTERIOR -
cerebral peduncles are the white matter tracts carrying corticospinal, corticobulbar and corticopontine fibres
Just behind the peduncles is the thin line of substantia nigra - involved in parkinsons and ballisumus

MIDDLE -
the tegementum is the region from substantia nigra to the aqueduct. The white matter tracts are the medial longitudinal fasciculus, the medial and lateral lemnisci and the spinothalamic tract. These tracts all carry sensory info from the body and ears (hearing and balance). The peduncles decussate at the level of the inferior colliculi.
The grey matter includes the red nucleus, which relays motor signals from GP and cerebllum, the paired nuclei are central in the midbrain.
The cranial nerves are CN3 anterior to the aqueduct at the level of the superior colliculus (runs anterior) and CN4 anterior to the 4th ventricle at the level of the inferior colliculus. Runs posteriorly but crosses over before exiting midbrain (decussates behind ventricle).

POSTERIOR:
The tectum or quadrigeminal plate is made up of the 4 colliculi - superior are visual (connect to lateral geniculate) and inferior are auditory (connect to medial geniculate) - MNEMONIC = MIA (medial inferior auditory)

RELATIONS:
ant - interpeduncular cistern - CN3 runs through here
post - quadrigeminal plate cistern (CN4)
lateral - ambient cistern (CN4 as it wraps around midbrain to enter meckels cave)

Blood supply: Small perforating branches from vertebrobasillar system.

Front 38

Pons

Back 38

Bulbous, sitting between the midbrain and medulla. Made up of cranial nerve nuclei, grey and white matter fibres.

CRANIAL NERVES: 5,6,7
At upper region (level of superior cerebellar peduncle) is the nuclei of the trigeminal nerve, just lateral to the origin of the peduncle. The most medial is the motor nucleus. Posterolateral is the mesencephalic nucleus, and anterolateral is the main sensory nucleus. The nerve runs forward and lateral to leave the pons at the ventrolateral aspect.

In the lower level (the level of the middle, biggest, cerebellar peduncle) is the nerve bodies for the abducens and facial nerves.

The abducens is just anterior to the 4th ventricle, and the nerve runs directly forward to exit anteriorly, either side of the groove of the ventral pons.

The facial nuclei are lateral to this, in order of anterior to posterior they are the motor nucleus, the superior salivary nucleus and the solitary nucleus. The latter 2 nuclei are elongated and extend into the upper medulla.
The nerve fibres pass backwards from the motor nucleus, curl around the abducens nucelus and then pass forward and lateral to exit in between the medulla and pons anterolaterally

.DORSAL REGION:
Contains fibres of the medial longitudinal fasciculus - relay between vestibular and oculomotor systems for balance - adjacent to the 4th ventricle.
Other tractss not visualised are the spinothalamic tracts, and the medial and lateral lemnisci.

VENTRAL REGION:
Also called the pontine body, contains-
corticospinal, corticobulbar and corticopontine tracts.
many transverse pontine fibres which make up most of the bulk

Relations:
ant - prepontine cistern (CN6 through here)
post - 4th ventricle
lat - cerebellopontine angle cistern (CN7 through here)

Blood supply -
medial branches of SCA
perforating branches off basillar

Front 39

Medulla

Back 39

The lower part of the brainsterm, transitioning between brainstem and spinal cord.

CRANIAL NERVES: 8-12
The vestibulocochlear nuclei lie at the very top of the medulla, in the region known as the restiform body, at the level of the inferior cerebellar peduncle.
The vestibular nuclei (medial and lateral) are posterior, in the floor of the fourth ventricle. The cohclea nuclei (dordsal and ventral) are in the most lateral portion which bulges outward (this is the actual restiform body). The VC nerve exits at the apex of the restiform body laterally, and passes anterolaterally to the IAM.

Cranial nerves 9-11 share common nuclei in the mid posterolateral medulla. The solitary tract and nucleus ambiguus are elongated and run through most of the medulla.

CN9 - nucleus ambiguus (most anterior, behind the olive laterally), solitary tract nucleus (posterolateral) and inferior salivatory nucleus. The nerve exits the medulla in the mid level of the post olivary sulcus.
CN10 - Nucleus ambiguus, solitary tract nucleus and dorsal vagal nucleus (posterior medulla, medial to solitary tract and lateral to hypoglossal nucleus). CN10 nerve exits medulla in postolivary sulcus between 9 and 11.
CN11 - Lower nucleus ambiguus. Exits at lowest part of postolivary sulcus, below CN10;
CN12 - Arises im hypoglossal nuclei, the most posteromedial, which actually bulge into the 4th ventricle as the hypoglossal emminence. The nerve fibres pass anteriorly and exit the medulla anteriorly in the pre-olivary sulcus in the mid medulla.

VENTRAL REGION:
There are two sets of lumps ventrally:
The medullary pyramids, seperated by the ventral median fissure. The pyramids carry the ipsilateral corticospinal tracts to the decussation.
The medullary olives laterally, seperated from the pyramids by the preolivary sulcus. These are made up of 4 olivary nuclei (superior, inferior - the biggest -, dorsal and accessory). These nuclei are involved in various functions, including transmitting spinocerebellar tracts.

DORSAL REGION:
At the very top of the medulla is a lateral extension to the inferior cerebellar peduncle called the restiform body. Contains CN8 nuclei.
Hypoglossal emminence in the mid medulla posteriorly, seperated by the dorsal median sulcus.
In the lower medulla are 2 sets of lumps, medially the gracile tubercles (caused by nuclei gracilis) and laterally the cuneate tubercles (nuceli cuneatus).
Posterior to these is the 4th ventricle.

Blood supply:
Vertebrobasillar including vertebral arteries (perf branches)
PICAs
anterior spinal arteries

Front 40

Cerebellum

Back 40

A bulbous bi-lobed posterior structure in the posterior fossa.

It is divided into 2 hemispheres by a central fissure, and has a central vermis which passes between the hemispheres.
The cerebellum communicates with the brainstem via 3 sets (sup, mid, inf) of paired peduncles.
The hemispheres are divided into lobes/lobules by transverse fissures.
Made of grey and white matter, and contains 4 paired nuclei.

PARTS:
There are grossly 5 portions of the hemispheres, divided by major sulci, which are further divided by relationships with the lobules of the vermis.

The superior surface is divided by the primary tentorial fissure, seperating anterior and posterior regions.
The superior surface is seperated from the inferior surface by the horizontal fissure.
The inferior surface is divided into superior and inferior parts by the prepyramidal fissure, which runs anterosuperiorly.
The anterior surface is bounded by the 4th ventricle and is not super relevant.

VERMIS:
The vermis is more clearly divided into lobules. These do relate to lobules of the cerebellar hemispheres, which will be shown in brackets.

Superiorly the most anterior lobule of the vermis is the lingua (wing of lingula). It is a thin sheet of tissue. The remaining anterior superior region is made up equally of the central lobule (wing of central lobule) and the culmen (quadrangular lobe). Behind these is the primary tentorial fissure.

The posterior superior surface is made up of, equally, the declive (simple lobule) and the folium (superior semilunar lobule). Beneath this is the horizontal fissure.

The superior inferior surface is made of the tuber (inferior semilunar lobule). Beneath this is the prepyramidal fissure.

The inferior inferior surface containes almost equally the pyramid (biventral lobe), uvula (tonsils) and nodulus (flocculus).

NUCLEI: Deep in the cerebellat white matter, the nuclei are clustered together and defined by location:
Anterior (Emboliform), medial (Fastigial), posterior (Globose) and lateral (Dentate) nuclei.

PEDUNCLES:
Superior:
Small, connects to the midbrain and communicates with the berebrum, red nuclei and thalamus.
Middle:
Thick, connect to pons. Is essentially continuation of corticopontine tracts and fibres from pontine nuclei.
Inferior:
Small, connects to medulla at restiform body. Contains connections to spinocerebellar tracts and connections from vestibular nuclei.

VERMIS:
Anterior at top, smoothly congruent with hemispheres. Moves posterior at bottom, contained in a deep depression called the posterior cerebellar incisura (the cleft between hemispheres)

Blood supply:
Vertebrobasillar -
SCA, AICA, PICA

Relations:
Surround by the cerebellar cistern.
This is related to the 4th ventricle by the bilateral Foramen of Luschka between the middle and inferior cerebellar peduncles.
Related to the 4th ventricle by the foramen of Magendie in the midline below the tonsils.
Downwards the cerebellar cistern is continuous with the cisterna magna

Function:
Motor control, attention and some language functions.

Front 41

Cisterns:

Back 41

Anterior to brainstem -
Premedullary cistern
Prepontine cistern
Interpeduncular cistern
and anteriorly the suprasellar cistern

Intermediate:
Ambient cistern between the suprasellar and quadrigeminal plate cistern.

Cisterns posterior to brainstem:
Cisterna magna (below cerebellum, to origin of spinal canal)
Cerebellar cistern - around cerebellum, only a cisternal space in the superior cerebellar cistern above the cerebellum.
Quadrigeminal plate cistern behind the quadrigeminal plate.
Cistern of the velum interpositum - communicates with quadrigeminal plate cistern. Between the 3rd ventricle below and the fornix and corpus above.