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Anatomy > Neuro > Flashcards

Neuro Flashcards

1
Q

Basal Ganglia: Description

A

The basal ganglia is a group of nuclei located in the deep white matter of the brain. That is interconnected with the cerebral cortex, thalami and brain stem.
Function: Memory formation and regulation of motor control

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2
Q

Basal Ganglia: Gross Anatomy

A
  • Gross anatomy:
  • It contains 3 paired nuclei that together comprise the corpus striatum:
    • Caudate nucleus
    • Putamen
    • Globus pallidus
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3
Q

Caudate Nucleus

A
  • Located lateral to the lateral ventricle
  • Head indents the anterior horn
  • Curves along the lateral ventricle
  • Tail extends into the temporal lobe
  • Bounded laterally by the internal capsule
  • The head of the caudate is supplied by the recurrent artery of Heubner, the rest is supplied by the lenticulostriate arteries
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4
Q

Putamen

A
  • Paired rounded, most lateral structure of the basal ganglia
  • Medial to the external capsule
  • Connected to the substantia nigra and subthalamic nuclei to control movement
  • Supplied by the lenticulostriate arteries
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5
Q

Globus Palladus

A
  • Paired, medial to the putamen, lateral to the thalamus
  • Subdivided into internal and exernal parts separated by the internal medullary lamina.
  • Supplied by the lenticulostriatal arteries
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6
Q

Subthalamic Nuclei

A
  • Small, located inferior to the thalamus
  • Medial to internal capsule
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7
Q

Substantia Nigra

A
  • Anterior midbrain, transition point of the tegmentum and cerebral peduncles
  • Produces dopamine
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8
Q

Cerebellum: Description

A

There cerebellum is brain structure located in the posterior fossa below the tentorium and behind the brain stem
Function: Integration and mediation of proprioceptor and movement data

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9
Q

Cerebellum: Gross Anatomy

A
  • Globular structure located in the posterior aspect of the posterior fossa
  • Three surfaces: anterior, superior and inferior
  • Three fissures: Primary, horizontal and sub-occipital
  • Two hemispheres: right and left
  • Single median vermis
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10
Q

Cerebellar divisions

A
  • Vermis: Divided into nine lobules
  • Cerebellar hemispheres:
  • Onion configuration of folia
  • 18 lobules associated bilaterally associated with the vermis lobules
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11
Q

Cerebellum/Cerebrum connections

A
  • Midbrain via the superior cerebellar peduncle
  • Pons via the middle cerebellar peduncle
  • Medulla via the inferior cerebellar peduncle
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12
Q

Cerebellum: Vasculature

A
  • Arterial supply:
    • Superior cerebellar arteries (from basil)
    • Anterior and posterior inferior cerebellar arteries (basil and vertebral)
  • Venous drainage:
    • Occipital venous sinus
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13
Q

Cerebellar: Relations

A
  • Anterior: 4 th ventricle
  • Posterior: cisterna magna
  • Superior: occipital lobes
  • Inferior: basiocciput
  • Lateral: cerebella-pontine angle cisterns
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14
Q

Cerebellar Variants

A
  • Variable blood supply
  • Megacisterna magna
  • Tonsilar ectopia / Chiari malformation
  • Agenesis
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15
Q

Corpus Callosum: Description

A
  • The corpus callosum is the largest white matter tract in the brain
  • Function: Interhemispheric communication
  • Location: Between the cerebral hemispheres above the septum pellucidum
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16
Q

Corpus Callosum: Gross Anatomy

A
  • C-shaped – concave up
  • 10cm in length

Divisions:

  • Rostrum anterior and inferior part (anterior hook of the c) continues as the copula then lamina terminalis
  • Genu most anterior part (elbow like bend), location of forceps minor
  • Body largely linear most superior part
  • Splenium most posterior part location of forceps major
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17
Q

Corpus Callosum: Vasculature

A
  • Arterial supply:
    • Anterior and posterior pericallosal arteries (From ACA and PCA)
    • Subcollosal artery
  • Veins:
    • Anterior and posterior pericallosal veins draining into the deep cerebral veins
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18
Q

Corpus Callosum: Relations

A
  • Superior: Interhemispheric fissure, indusium griseum, falx cerebri, cingulate gyrus, callosal sulcus
  • Inferior: septum pellucidum anteriorly and the body of the fornix posteriorly
  • Lateral: corona radiata
  • Anterior: Frontal lobes, fornix anterior
  • Posterior: occipital lobes, fornix posterior
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19
Q

Corpus Callosum: Variants

A
  • Agenesis/dygenesis of the corpus callosum
  • Cavum septum pellucidum
  • Cavum et vergae
  • Cavum veli interpositi
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20
Q

Internal Capsule: Description

A
  • The internal capsule is a deep subcortical structure that contains a concentration of white matter projections.
  • Function: Transmision of the motor and sensory information to and form the cortex and the rest of the CNS
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21
Q

Internal Capsule: Gross anatomy

A
  • Divided into 5 parts:
  • Anterior limb: lies between the head of the caudate nucleus medially and the lentiform nucleus laterally. Contain thalamic radiations.
  • Genu: Medial to the apex of the lentiform nucleus. Contains corticobulbar tracts.
  • Posterior limb: between the thalamus and the lentiform nucleus. Contains corticospinal tracts.
  • Retrolentiform: behind the lentiform nucleus. Contains optic radiation.
  • Sublentiform: below the lentiform nucleus. Contains the auditory radiation.
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22
Q

Internal Capsule: Vasculature

A
  • Arterial:
    • Perforators from the MCA and ACA
    • Lenticulostriatal and recurrent artery of Heubner.
    • Internal carotid supplies the posterior limb
  • Venous:
    • Internal cerebral vein
    • Inferior sagittal sinus
    • Posterior vein of the corpus callosum
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23
Q

Temporal Lobe: Description

A

The temporal lobe is one of four lobes of the brain and largely occupies the middle cranial fossa
Function: Memory formation, communication

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24
Q

Temporal lobe: Gross Anatomy

A
  • Gross anatomy:
    • Second largest lobe (after the frontal lobe)
  • Borders:
    • Superiorly – Sylvian fissure
    • Posteriorly – imaginary parietotemporal line
    • The middle cranial fossa forms its anterior and inferor boundaries
  • The temporal lobe can be divided into two main sections:
    • Neocortex – lateral and inferolateral surfaces
    • Mesial temporal lobe – hippocampus, amygdala, parahippocampal gyrus
  • The temporal lobe is divide into five gyri, from superolateral to inferomedial:
    • Superior temporal gyrus – containing Wernicke’s area
    • Middle temporal gyrus
    • Inferior temporal gyrus
    • Fusiform gyrus
    • Parahipocampal gyrus (anterior) lingual gyrus (posterior)
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25
Q

Temporal Lobe: Vasculature

A
  • Arterial supply:
    • Anterior choroidal
    • Middle cerebral
    • Basilar
  • Venous drainage:
    • Superficial middle cerebral vein
    • Inferior anastomotic vein of Labbe
    • Posterior choroidal vein
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26
Q

Temporal Lobe: Variants

A

Wernicke’s area can be on either side, most commonly the left

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27
Q

Frontal lobe: Description

A

The frontal lobe is by far the largest of the four lobes of the cerebrum (along with the parietal lobe, temporal lobe, and occipital lobe), and is responsible for many of the functions which produce voluntary and purposeful action.

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28
Q

Frontal Lobe: Gross Anatomy

A

The frontal lobe is the largest lobe accounting for 41% of the total neocortical volume. The frontal lobe resides largely in the anterior cranial fossa. Its most anterior part is known as the frontal pole, and extends posteriorly to the central (Rolandic) sulcus which separates it from the parietal lobe.
Posteroinferiorly it is separated from the temporal lobe by the lateral sulcus (sylvian fissure), although not seen from the surface is the insular cortex which is hidden deep to the lateral sulcus
The interhemispheric fissure separates its medial surface from the contralateral frontal lobe.
The frontal lobe is roughly pyramidal in shape, with three cortical surfaces:

  • Lateral surface (largest)
  • Medial (inter-hemispheric) surface
  • Inferior surface
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29
Q

Frontal Lobe: Lateral surface

A
  • Gyri:
    • superior frontal gyrus
    • middle frontal gyrus
    • inferior frontal gyrus
    • precentral gyrus (primary motor area)
  • Sulci:
    • superior frontal sulcus
    • inferior frontal sulcus
    • precentral sulcus
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30
Q

Frontal lobe: Medial Surface

A

The medial surface of the frontal lobe, abutting the falx in the midline, is primarily divided by the curving cingulate sulcus, which parallels the outer outline of the corpus callosum.
Above the cingulate sulcus is the medial continuation of the superior frontal gyrus
which is usually divided into two parts by a short ascending branch from the cingulate sulcus.

  • medial frontal gyrus
  • paracentral lobule
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31
Q

Frontal lobe: Inferior surface

A

Gyrus recti medially
Orbital gyri arranged in a H configuration (Medial, lateral, anterior and posterior orbital gyri)

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32
Q

Frontal Lobe: Relations

A
  • anterior: frontal bone
  • superiorly: frontal bone (anteriorly), coronal suture, and parietal bone (posteriorly)
  • posterior: central sulcus and parietal lobe
  • inferolaterally: lateral sulcus and temporal lobes
  • inferior: floor of anterior cranial fossa
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33
Q

Frontal lobe: Arterial supply

A
  • middle cerebral artery (MCA): lateral frontal lobe
  • anterior cerebral artery (ACA): medial frontal lobe
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34
Q

Occipital lobe: Description

A

The occipital lobe is the smallest of the four lobes of the brain.
Location: Posterior to the temporal and parietal lobes, sitting on top of the tentorium
Function: Primary and secondary visual cortex

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35
Q

Occipital Lobe: Gross anatomy

A
  • Triangular in shape
  • Separated from the parietal and temporal lobes by the parieto-occipital sulcus and the parietotemporal line
  • Medially it is devided into hemisphere by the longitudinal fissure
  • The calcarine sulcus runs horizontally across with the cuneus above and the lingual gyrus below
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36
Q

Occipital lobe: Functional areas

A
  • Primary visual cortex – primary visual processing
  • Secondary visual cortex – visual association
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37
Q

Occipital Lobe: Relations

A
  • Anterior: parietal and temporal lobes
  • Posterior: occipital bone
  • Superior: Parietal lobe and parietal bone
  • Inferior: tentorium cerebelli
  • Medial: transverse sinuses, confluence of sinuses, straight sinus
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38
Q

Occipital lobe vasculature

A
  • Arterial supply:
    • Branches of the posterior cerebral artery
  • Venous:
    • Straight sinus
    • Superior sagittal sinus
    • Transverse sinuses
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39
Q

Parietal Lobe: Description

A

The parietal lobe is one of the four lobes of the brain located between the frontal and occipital lobes.
Function: Sensory processing, communication, proprioception

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40
Q

Parietal Lobe: Gross Anatomy

A
  • Lobe extends from the central sulcus anteriorly to the parieto-occipital fissure posteriorly.
    • The lateral sulcus corresponds to its inferolateral boundary, separating it from the temporal lobe. Divided by the medial longitudinal fissure

Gyri:

  • postcentral gyrus (primary sensory area)
  • superior parietal lobule
  • inferior parietal lobule (Wernicke’s area)
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41
Q

Parietal Lobe: Relations

A
  • Anterior: frontal lobe
  • Posterior: occipital lobe
  • Superior: parietal bone
  • Inferior: temporal lobe
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42
Q

Parietal lobe: Vasculature

A
  • Blood supply:
    • middle cerebral artery (MCA)
    • anterior cerebral artery (ACA): medial parietal lobe
    • posterior cerebral artery (PCA): posterior medial parietal lobe
  • Venous:
    • Superior sagittal sinus
    • Straight sinus
    • Inferior superficial cerebral vein (Labbe)
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43
Q

Insula lobe: Description

A

Small deep paired lobe of the brain, covered by the frontal, parietal and temporal opercula (lids).
Function:

  • The insula has a number of disparate functions, serving as the primary gustatory cortex, as well as having important connections to language and visual-vestibular integration. Additionally, it also has important autonomic function, particularly sympathetic tone from the right insula; damage to this area has been associated with cardiac arrhythmias.
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44
Q

Insula lobe: Gross Anatomy

A
  • Deep to the lateral sulcus (Sylvain fissure)
  • The insula is shaped like a irregular pyramid, with its trapezoid base facing medially.
  • The base is circumscribed by the circular sulcus, although, more precisely, it is bounded by four peri-insular sulci: anterior, inferior, superior, and posterior 3-4.
  • The apex points laterally into the Sylvian fissure.
  • The insular cortex is divided into two lobules, anterior and posterior, by the central sulcus of the insula, which passes obliquely from posterosuperior to anteroinferior.
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45
Q

Insula: Arterial Supply

A

The insula is supplied by perforating branches from the middle cerebral artery (MCA), usually from the M2 segment.

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46
Q

Circle of Willis: Description

A

The circle of Willis is an arterial polygon that supplies the brain
Location: Suprasellar cistern around the pituitary infundibulum
Function: Anastomotic supply of oxygenated blood to the brain

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47
Q

CoW: Gross Anatomy

A

Dividable into anterior and posterior circulations

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48
Q

CoW: Anterior Circulation

A

Supplied by the internal carotid arteries
Branches:

  • Middle cerebral arteries
  • Anterior cerebral arteries
  • Anterior communicating artery
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49
Q

Cerebral meninges: Description

A

There cerebral meninges are the coverings of the brain

Function:

Protect the brain, circulation of CSF, venous return

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50
Q

Cerebral meninges: Gross Anatomy

A

3 layers in total:

  • Dura mater – outer most, has outer endosteal layers and inner meningeal layers, folds of the dura mater make the dural venous sinuses, also known as the pachymeninges
  • Arachnoid mater – diffuse fibrous middle layer, CSF space is deep to the arachnoid mater, does not extend in the sulci
  • Pie mater – closely adhered to the brain very thin, extends into the sulci
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51
Q

Cerebral meninges: Neurovasculature

A

Arterial supply:

  • Anterior meningeal arteries
  • Middle meningeal arteries
  • Posterior meningeal arteries

Venous drainage:

  • Multiple unnamed veins into the dural venous sinuses

Dural venous sinuses:

  • Superior and inferior sagittal sinuses
  • Straight sinus
  • Transverse sinuses
  • Sigmoid sinuses
  • Sphenoparietal sinus
  • Superior and inferior petrosal sinuses
  • Cavernous and anterior and posterior intercavernous sinues

Innervation:

Meningeal nerves branches of the:

  • Trigeminal nerves
  • Glossopharyngeal nerves
  • Vagus nerves

Lymphatics:

Deep cervical

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52
Q

Cerebral meninges: Variants

A
  • Mega cisterna magna
  • Absence of the confluence of sinuses
  • Arachnoid cysts
  • Dural calcifications
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53
Q

Ventricles: Description

A

The cerebral ventricular system is a system of cerebraospinal fluid spaces connected by formaminae.

Function: Circulation of cerebrospinal fluid

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54
Q

Ventricles:Gross anatomy

A

Contains 20-25ml of CSF in normal adult

2 lateral ventricles, 3rd ventricle and a forth ventricle

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55
Q

Lateral Ventricle

A
  • One in each cerebral hemisphere
  • Each has a frontal horn, body, temporal horn and an occipital horn
  • Each communicates with the third ventricle by means of an interventricular foramen (of Munro) at the junction of the anterior horn and body
  • Contains the choroid plexus which produces CSF
  • Frontal horn relations
    • roof: corpus callosum (rostrum / genu)
    • lateral: caudate nucleus
    • medial: septum pellucidum
  • Body relations
    • roof: corpus callosum body
    • medial: septum pellucidum
    • floor: thalamus
  • Temporal horn relations
    • lateral: tapetum of the corpus callosum
    • roof: tail of caudate nucleus, amygdaloid nucleus
    • floor: hippocampus
  • Occipital horn relations
    • lateral: tapetum of corpus callosum
    • floor: collateral sulcus
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56
Q

3rd Ventricle

A
  • The third ventricle is a slit-like cavity between the thalami
  • Sometimes the thalami are connected to each other, forming the interthalamic adhesion
  • Relations
    • lateral: thalamus
    • floor: hypothalamus
    • roof: anterior commissure, body of fornix
    • anterior: lamina terminalis
  • Has several recesses:
    • supra-optic recess (above the optic chiasm)
    • infundibular recess (above the pituitary stalk)
    • posteriorly there is a pineal and suprapineal recesses
  • Choroid plexuses of the third ventricle invaginates the roof of the ventricle
  • Cerebral aqueduct is the narrow channel in the midbrain that connects the third and fourth ventricles
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57
Q

Fourth Ventricle

A
  • Extends from the cerebral aqueduct (of Sylvius) to the obex and is filled with CSF
  • Relations:
    • roof: cerebellum
    • floor (ventrally): rhomboid fossa (formed by the back of the pons and medulla oblongata)
    • lateral walls: cerebellar peduncles
  • CSF enters the ventricle via the cerebral aqueduct and leaves via one of four routes:
    • via the obex and into the central spinal canal
    • via the median aperture (of Magendie) into the cisterna magna
    • via ones of the two lateral apertures (of Luschka) into the cerebellopontine cistern
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58
Q

Choroid plexus

A

Small vascular organs located in all ventricles except the anterior and occipital horns of the lateral ventricles, produce CSF, arterial supply anterior and posterior coroidal arteries

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59
Q

Ventricle: Variant anatomy

A
  • Cavum septum pellicidum
  • Cavum vergae
  • Cavum veli interpositi
  • Interthalamic adhesion may not be present
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60
Q

Pituitary Gland: Description

A

The pituitary gland is the main exocrine interface between the central nervous system and the rest of the body

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61
Q

Pituitary gland: Gross anatomy

A

Location: with the sella turcica

Dividable into anterior and poster components:

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62
Q

Anterior pituitary

A

The anterior pituitary is surrounded by a thin fibrous capsule with thin septa extending into the gland

Parts:

  • Pars distalis – arises from the anterior wall of the Rathke’s pouch
  • Pars tuberalis – surrounds the anterior aspect of the infundibular stalk
  • Pars intermedia – thin epithelial layer between the pars distalis and the neurohypophysis

Hormones produced – GH, FSH, TSH, ACTH, LH, FSH, Prolactin

Blood supply: Portal system supplied by the superior hypophyseal artery (ophthalmic portion of the internal carotid artery)

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63
Q

Posterior pituitary

A

Direct extension from the hypothalamus

Does not synthesise but releases ADH and oxytocin which has travelled down the stalk via herring bodies from the supraoptic and paraventricular nucleus of the hypothalamus

The infundibular stalk is considered part of the posterior pituitary

Blood supply: Inferior hypophyseal network primary supplied by the inferior hypophyseal artery (from the meningohypophyseal trunk)

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64
Q

Pituitary gland: Relations

A
  • Inferior – sphenoid sinus
  • Anterior – clinoid process and anterior intercavenous sinus
  • Laterally – the cavernous sinuses
  • Superior – the diaphragma sellae and the suprasellar cistern
  • Posterior – posterior intercavernous sinus and dorsum sellae
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65
Q

Pituitary gland: Variants

A
  • Hypoplasia
  • Empty sella
  • Duplication
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66
Q

Pons: Description

A

The pons is the middle of the three parts of the brainstem, sitting above the medulla and below the midbrain. It acts as a relay between the cerebellum and cerebral hemispheres.

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67
Q

Pons: Gross anatomy

A

The pons has a bulbous shape and has two main components - the ventral pons and the dorsal tegmentum.

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68
Q

Ventral Pons

A

The ventral pons consists of white matter tracts (corticospinal, corticobulbar and corticopontine tracts) with transverse fibres contributing to the bulk of the pons.

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69
Q

Dorsal Tegmentum

A

The dorsal tegmentum is continuous with the tegmentum of the medulla and the midbrain. It contains multiple white matter tracts (medial longitudinal fasciculus, medial lemniscus, lateral lemniscus) and grey matter nuclei (cranial nerves). Within the dorsal tegmentum lie four cranial nerve nuclei:

  • trigeminal nerve (CN V): many motor, sensory and mesencephalic nuclei extending from the pons to the upper cervical cord
  • abducens nerve (CN VI): motor nucleus
  • facial nerve (CN VII): including superior salivary, motor and solitary tract nuclei
  • vestibulocochlear nerve (CN VIII): including vestibular and cochlear nuclei

Posteriorly, the pons is connected to the cerebellum by the middle cerebellar peduncle.

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70
Q

Pons: Relations

A
  • Anteriorly: prepontine cistern (contains CN V & VI)
  • Laterally: cerebellopontine angle cistern (contains CN VII & VIII)
  • Posteriorly: fourth ventricle (the pons makes up the anterior wall)
  • Superiorly: continuous with the midbrain
  • Inferiorly: continuous with the medulla
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71
Q

Pons: Vasculature

A

Arterial:

  • medial branches of the superior cerebellar artery
  • pontine branches of basilar artery

Venous:

  • Lateral and transverse pontine veins
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72
Q

Pons: Variants

A
  • Basilar artery fenestration
  • Pontine artery branches from the superior cerebellar artery or anterior inferior cerebellar artery
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73
Q

Thalamus: Description

A

The thalamus is the largest structure of the diencephalon

Function: Relay centre, consciousness, sleep and memory

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74
Q

Thalamus: Gross anatomy

A
  • Composed of 2 symetrical egg shaped masses which are typically connected midline by the interthalamic adhesion.
  • The grey matter of the thalamus is divided by a y shaped layer of white matter called the internal medullary lamina. This divides the thalamus into anterior, medial and lateral parts.
  • The thalamus contains over 50 distinct nuclei.
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75
Q

Thalamus: Relations

A
  • Superior: Body of the fornix and the head of the caudate
  • Lateral: posterior limb of the internal capsule
  • Medial: 3rd ventricle and interthalmic adhesion
  • Inferior: Hypothalamus
  • Anterior: Interventricular foramen of Monroe
  • Posterior: Occipital horns of the lateral ventricle
76
Q

Thalamus: Vasculature

A

Arterial supply:

  • Perforating vessels from the posterior cerebral, posterior communicating and basilar arteries

Venous drainage:

  • Internal cerebral vein

Lymphatics:

  • Via CSF
77
Q

Thalamus: Variants

A
  • Absence of the interthalmic adhesion
  • Artery of Percheron (single vessel from the PCA supplying the medial thalamus)
78
Q

Visual Pathways:Description

A

The visual pathways transmit visual information from the retina within the eyes to the primary visual cortex of the occipital lobe as well as the pre tectal nuclei and superior colliculi

79
Q

Visual Pathway: Extracranial

A
  • Bipolar neurons (first order) on the retina receive light signals and synapse with ganglion cells (second order) locally.
  • Axons from the ganglia exit via the optic disc to form the optic nerves
  • Each optic nerve carries the information from one eye, they are covered in meninges
  • They pass through the optic canals, with the ophthalmic arteries.
80
Q

Visual Pathway: Intracranial

A
  • The optic nerves continue posteriorly in the suprasella cistern
  • They converge at the optic chiasm anterior to the pituitary stalk
  • Fibres from the nasal side of the retina decussate at the optic chiasm, fibres from the temporal side do not
  • The optic tracts continue posteriorly from the optic chiasm terminating in the lateral geniculate nuclei of the thalamus (small fibres also enter the midbrain)
  • From the lateral geniculate nuclei third order neurons form the optic radiations
  • The optic radiation continues posteriorly to the primary visual cortex
  • The upper division contains information from the superior rentinal quadrants, it terminates in the upper bank of the calcraine fissure
  • The lower division contains information from the inferior rentinal quadrants, it terminates in the lower bank of the calcarine fissure
81
Q

Visual pathway: Blood supply

A
  • Retina and distal 1/3 of optic nerve in orbit: central retinal artery
  • Proximal 2/3 of optic nerve in orbit: ophthalmic artery
  • Intracranial optic nerve and optic chiasma: anterior cerebral artery small branches and superior hypophyseal artery
  • Optic tract: small branches of the anterior choroidal artery and posterior communicating artery
82
Q

Arterial supply of the cerebellum: Description

A

The cerebellum is a specialised part of the brain located in the posterior cranial fossa

Function: Computation of movement and proprioceptive data

83
Q

Arterial supply of the cerebellum

A
  • Superior cerebellar from the basilar –supplies the superior surface
  • Anterior inferior cerebellar from the basilar – anterior inferior
  • Posterior inferior cerebellar from the vertebral – posterior inferior
84
Q

Basilar artery: Description

A

The basilar artery is a large artery of the posterior circulation of the brain.

85
Q

Basilar artery: Gross anatomy

A

Origin: Formed from the confluence of the vertebral arteries at the base of the pons.

Course: Ascends parallel to the ventral pons in the central groove of the pons in the pre-pontine cistern

Branches: Numerus small braches to the pons and cerebellum including the:

  • The anterior inferior cerebellar artery (AICA)
  • Labyrinthine arteries (normally from AICA)
  • Superior cerebellar arteries

Termination: bifurcates to form the two posterior cerebral arteries at the upper pontine boarder

86
Q

Basilar artery: Relations

A
  • Anterior: clivus
  • Posterior: Basilar pons
  • Superior: Posterior cerebral arteries
  • Inferior: vertebral arteries
  • Lateral: Origin; origin of the abducens nerve, termination: origin of the oculomotor nerve
87
Q

Basilar artery: Variants

A
  • Persistent carotid-vertebrobasilar anastomoses (mnemonic: TOHP)
  • Basilar artery fenestration / Island formation
  • Basilar artery forms in caudal position
  • Basilar artery is continuation of only one vertebral artery
  • Two basilar arteries with otherwise normal branches
  • Anastomosing network instead of a basilar artery
88
Q

Internal carotid artery: Description

A

Internal carotid arteries are the primary supply to the anterior circulation of the brain

Function: supply oxygenated blood to the brain and meninges

89
Q

Internal Carotid Artery: Gross anatomy

A

Divides into the following segments (Bouthillier classification):

  • Cervical
  • Petrosal
  • Lacerum
  • Clinoid
  • Caverous
  • Ophthalmic
  • Communicating

Origin:

Bifurcation of the common carotid at the level ~C4

Course: ascending through the carotid space, enters the cranial cavity via the carotid canal

Termination: Branches to for the anterior and middle cerebral arteries

90
Q

Internal carotid artery: Branches

A

2nd segment:

  • Caroticotympanic
  • Vidian

4th segment:

  • Meningohypophyseal
  • Inferolateral trunk

6th segment

  • Ophthalmic artery
  • Superior hypophyseal

7th segment:

  • Posterior communicating artery
  • Anterior choroidal artery
  • Anterior communicating artery
  • Middle cerebral artery
91
Q

Internal carotid artery: Relations

A
  • Anterior: External carotid artery
  • Lateral: internal jugular vein
  • Medial: larynx, oropharynx, nasopharynx
  • Superior: suprasellar cistern
  • Inferior: Carotid bulb
92
Q

Internal Carotid artery: Variants

A
  • Aberrant ICA course
  • Kissing carotids
  • Persistent carotid-vertebrobasilar anastomoses
  • Retropharyngeal ICA
93
Q

Middle cerebral artery: Gross anatomy

A

Origin: Terminal bifurcation of the Internal carotid artery (the other branch is the anterior cerebral artery

Course:

Divided into segments: (HIOC)

  • M1 – the horizontal segment – from origin to bi/trifurcation
  • M2 – insular segment from bi/trifurcation to the circular sulcus of the insular lobe
  • M3 – Opercular branches – within the sylvian fissure
  • M4 – Cortical segment – branches emerging from the sylvian fissure
94
Q

MCA Branches

A

Branches:

M1: (PAUL)

  • Medial and lateral lenticulostriate
  • Anterior temporal
  • Polar temporal
  • Uncal artery

M2:

  • Superior and inferior trunks
95
Q

M1 Supply

A

M1:

  • Basal ganglia
  • External and internal capsule
  • Anterior third of the superior, middle and inferior temporal gyri
  • Polar Regions of the temporal lobe
96
Q

MCA Variants

A
  • MCA duplication
  • Accessory MCA
  • MCA fenestration
  • Early branching of the MCA
97
Q

Cavernous sinus

A

The cavernous sinuses are paired dural venous sinuses lateral to the pituitary fossa and body of the sphenoid bone.

Function: Return of deoxygenated blood from the basicerebrum to the systemic circulation

98
Q

Cavernous Sinus: Gross Anatomy

A

Formed from reflection of the dura mater

Spans from the apex of the orbit to the apex of the petrous temporal bone

Diaphragma sella, dural reflection slung between the clinoid processes

99
Q

Cavernous sinus: Tributaries

A
  • Sphenoparietal sinuses
  • Intercavenous sinuses anterior and posterior
  • Superior and inferior ophthalmic veins (inferior ophthalmic vein may drain to the pterygoid plexus)
  • Superfical middle cerebral vein (of Sylvius) (however this may drain into the sphenoparietal sinus)
100
Q

Cavernous Sinus: Drains to

A
  • Clival plexus
  • Paired superior petrosal sinus (to the transverse sinus)
  • Paired inferior petrosal sinus (to the jugular bulb)
  • Venous plexus of the internal carotid
101
Q

Cavernous sinus: Contents

A

Many important structures pass through the cavernous sinuses and there walls

OTOM CAT

Wall superior to inferior:

  • Oculomotor nerve
  • Trochlear nerve
  • Ophthalmic division of the trigeminal nerve
  • Maxillary division of the trigeminal nerve

Within the sinus:

  • Abduces nerve laterally
  • Internal carotid medially
102
Q

Cavernous sinus: Relations

A

Anterior: apex of the orbit

Posterior: cerebral peduncle

Medial: pituitary fossa, pituitary gland, sella turcica, hypophseal arteries and veins

Superior: suprasella cistern, optic chiasm

Inferior: Sphenoid sinus

Lateral: temporal lobes

103
Q

Cavernous Sinus: Variants

A
  • Inferior ophthalmic vein may not drain here
  • Septation
  • Absence
  • Empty sella
104
Q

Cerebral Venous sinuses: Description

A

The cerebral venous sinus are venous system formed from folds of the meninges

Function: return of deoxygentated blood from the brain to the system circulation

105
Q

Cerebral venous sinuses: Gross anatomy

A

Folded dura form sinus which drain from veins to other sinuses or veins

Valveless

There are paired and unpaired cerebral venous sinuses

106
Q

Paired Cerebral venous sinuses

A

Transverse sinuses – from the confluence of sinuses to the sagittal sinuses, receives the superficial cerebral vein of labbe

Sigmoid sinuses – from the transverse sinus s-shaped course draining into the jugular bulbs , also receives the sphenoparietal sinus and the superior petrosal sinus

Superior and inferior petrosal sinuses – From the right and left cavernous sinuses to the sagittal and jugular bulb respectively

Sphenoperietal sinus courses along the ridge of the greater wing of the sphenoid to the cavernous sinsus, also receives the middle superficial cerebral vein

Caverous sinuses located either side of the sella, receives the ophthalmic veins (superior and inferior) connected by the anterior and posterior intercavernous sinsus, drains into the superior and inferior petrosal sinuses and basiclival plexus

107
Q

Unpaired cerebral venous sinuses

A

Internal cavernous sinuses as noted earlier

Superior sagittal sinus midline between the falx drains into the confluence of sinuses

Inferior sagittal sinus runs in the over the corpus callosum drains into the straight sinus

Straight sinus – from the vein of Galen to the confluence of sinuses

Occipital sinus – from the occipital bone midline between the cerebellar hemispheres drains into the confluence of sinuses

108
Q

Cerebral venous sinuses: Variants

A

No confluence – straight and superior sagittal sinuses drain into the right and left transverse sinuses separately

No confluence – straight and superior sagittal sinuses fork prior to drain into the straight sinuses

109
Q

Cerebral venous drainage: Description

A

The cerebral veins drain the brain parenchyma and are located in the subarachnoid space. They pierce the meninges and drain further into the cranial venous sinuses.

110
Q

Cerebral venous drainage: Gross anatomy

A

The cerebral veins lack muscular tissue and valves.

The cerebral venous system can be divided into:

  • superficial (cortical) cerebral veins
  • deep (subependymal) cerebral veins
111
Q

Superficial cerebral venous system

A

There are numerous unnamed superficial veins

Large named veins include:

  • Superficial middle cerebral vein – Begins on the lateral surface, runs in the lateral sulcus, drains into the cavernous or sphenoparietal sinus
  • Superior anastomotic vein of Trolard – Runs over the lateral aspect of the brain, connects the superior sagittal sinus to the superficial middle cerebral vein
  • Inferior anastomotic vein of Labbe – Runs between the sylvian fissure and the transverse sinuses

The unnamed veins are typically called cortical veins. They run in the sulci and drain the adjacent gyri.

112
Q

Deep cerebral venous system

A
  • Medullary veins:
    • Numerous
    • Originate 1-2 cm below cortical gray matter
    • Pass through deep medullary white matter and drain into subependymal veins.
    • Arranged in a wedge-shaped manner and distributed at a right angle to subependymal veins.

Subependymal veins: receive medullary veins and aggregate into greater tributaries, mainly into:

Great vein of Galen:

  • Quadrigeminal cistern
  • Drains into the straight sinus
  • Connects to the internal cerebral veins and the basal veins of Rosenthal

Internal cerebral veins:

  • Runs beneath the corpus callosum in the roof of the thord ventricle
  • Drains: Great vein of Galen

Basal veins of Rosenthal

  • Runs: Medial temporal lobe surface lateral to midbrain through the ambient cistern
  • Drains: Great vein of Galen
113
Q

Venous drainage of the orbit

A

The venous drainage of the orbit is the venous system to drain deoxygenated blood from the orbit to the systemic circulation.

114
Q

Superior ophthalmic vein

A

Origin: confluence of multiple veins in the superior orbit

Course:

  • Medially toward the trochlea between the optic nerve and the rectus muscle
  • Curves laterally in the posterior orbit
  • Exits through the fibromuscular cone to leave the orbit via the superior

Termination:

Drains directly into the cavernous sinus

Drains:

  • Upper Globe
  • Upper extraoccular muscles
  • Lacrimal gland
115
Q

Inferior ophthalmic vein

A

Origin: Confluence of multiple small vessels in the anterior inferior orbit (including some small facial veins which means infection can be transmitted intracranially).

Course:

  • Posteriorly within the intraconal space

Termination:

  • Then exits the cone and forms 2 tributaries:
    • Branch through the superior orbital fissure to drain directly into the cavernous sinus
    • Branch drains through the inferior orbital fissure to drain into the pterygoid plexus

Drains:

  • Lower globe
  • Lower extraocular muscle
  • Lower eyelid
116
Q

Phrenic Nerve: Description

A

The phrenic nerves are mixed sensory/motor nerves that course through the neck and thorax to innervate the diaphragm

117
Q

Phrenic Nerve: Gross anatomy

A

Origin: ventral rami of C3, C4 and C5

Course: Passes of the anterior surface of scalenus anterior, over the dome of the apical pleura, entering the superior thoracic aperture posterior to the subclavian veins

Left:

Descends lateral to the left subclavian artery, passes anterior to the hilum, pierces the diaphragm directly to enter the abdominal cavity.

Right:

Descends with the superior and inferior vena cava. Enters the abdomen with the inferior vena cava through the caval hiatus at level T8

Within the abdomen the both divide in the anterior, lateral and posterior branches. Coursing out in a radial pattern.

Supply:

Sole motor supply to each hemidiaphragm, sensation to the central tendon

  • Diaphragm
  • Mediastinal pleura
  • Pericardium
  • Central diaphragmatic pleura
118
Q

Phrenic nerve: Variants

A
  • Course anterior to subclavian vein
  • May pierce the anterior scalene muscle
  • Accessory phrenic nerve
  • Contribution form C2 or C6
  • May supply branch to subclavius
119
Q

Sympathetic trunk: Description

A

The sympathetic chain is a component of the autonomic nervous system and is composed of general visceral afferent and efferent axons.

Function:

‘fight, fright or flight’ (sympathoadrenal) response

120
Q

Sympathetic trunk: Gross anatomy

A

Location

  • The sympathetic chain is external to the spinal column, adjacent to the vertebral bodies and within the perivertebral space. It is comprised of paired, longitudinally arranged, sympathetic ganglia linked together by myelinated axons forming the sympathetic trunk.
  • It extends from the upper neck to the coccyx.

23 paired sympathetic ganglia and 1 unpaired coccygeal sympathetic ganglion

Origin

The sympathetic chain and ganglia are comprised of discrete sympathetic ganglia (containing neuronal cell bodies) which communicate with each ganglion via the sympathetic trunk (containing myelinated axons).

121
Q

Sympathetic Trunk: Branches

A
  • Carotid plexus
  • superior, middle and inferior cardiac nerves form the superficial/deep cardiac plexus and pulmonary plexus - supplies the heart and bronchi
  • cardiac plexus
  • oesophageal plexus
  • thoracic aortic plexus
  • greater (T5-10) and lesser (T10-11) and least splanchnic (T12) nerves
  • Superior hypogastric plexus
  • Inferior hypogastric plexus
  • Sacral splanchinic nerves
122
Q

Sympathetic trunk: Blood supply

A
  • neck: ascending cervical artery and inferior thyroid artery
  • thorax: posterior intercostal arteries
  • abdomen: lumbar arteries
  • pelvis: lateral and median sacral arteries
123
Q

Sympathetic trunk: Lymphatic drainage

A
  • neck: deep cervical chain lymph nodes
  • thorax: posterior mediastinal lymph nodes
  • abdomen: para-aortic lymph nodes, cisterna chyli
  • pelvis: internal iliac lymph nodes
124
Q

Sympathetic Trunk: Variant anatomy

A
  • absent stellate ganglion
  • doubled superior cervical ganglion
  • absent superior cardiac branch (usually on the right)
125
Q

Pituitary Fossa: Description

A

The pituitary fossa is a midline, dural lined structure in the sphenoid bone that houses the pituitary gland.

126
Q

Pituitary fossa: Gross anatomy

A

The anterior, posterior and inferior walls are bony, the lateral walls and roof are formed by dural slings between the anterior and posterior clinoid processes.

There is a fenestration in the roof for the infundibulum.

There are four parts to the sellae:

  • Anterior: tuberculum sellae
  • Posterior: dorsum sellae
  • Inferior: sella turcica
  • Superior: Diaphragma sellae
127
Q

Pituitary Fossa: Contents

A
  • Pituatary gland
  • Pituatary vessels
  • Anterior and posterior intercavernous sinuses
  • CSF
  • Hypophyseal cistern
128
Q

Pituitary fossa: Relations

A
  • Ant/inf. – sphenoid sinus
  • Post – clivus, basilar artery, brainstem
  • Sup – suprasellar cistern, optic chiasm, infundibulum, hypothalamus
  • Lateral – cavernous sinus
129
Q

Pituitary fossa: Variants

A
  • Empty sella
  • Pneumatisation of the dorsum sellae
130
Q

Intracranial Cisterns: Description

A

The subarachnoid cisterns are discrete named spaces within the subarachnoid space where the pia mater and arachnoid membrane are not in close approximation. The subarachnoid tissue is not as abundant here as in the normal subarachnoid space and cerebrospinal fluid (CSF) gathers to form pools or cisterns (Latin: “box”).

As they are interconnected, the patency is essential for CSF circulation. Being within the subarachnoid space, the cisterns may have vessels and/or cranial nerves passing through them.

131
Q

Named intracranial cisterns (9)

A
  • cisterna magna: the largest of the subarachnoid cisterns
  • prepontine cistern: anterior to the pons
  • suprasellar cistern: surrounding the infundibulum
  • interpeduncular cistern: between the cerebral crura
  • quadrigeminal cistern: superior cistern or cistern of the great cerebral vein
  • ambient cistern: surrounds the back of the midbrain
  • cerebellopontine cistern: at the cerebellopontine angle
  • premedullary cistern: anterior to the medulla
  • sylvian cistern: superficial to the insular cortex
132
Q

Olfactory N: Description

A

The olfactory nerve (I) is the cranial nerve responsible for olfaction. It is the shortest of the cranial nerves.

Function: Special sensory – olfaction

Location: Roof of the nasal cavity

133
Q

Olfactory N: Gross Anatomy

A

The olfactory nerve is a collection of nerves extending from the olfactory epithelium to the olfactory bulb via the dura mater and many small perforations of the cribriform plate (of the ethmoid bone).

The olfactory bulb and tract are an extension of the central nervous system. It contains second order olfactory neurons.

The olfactory bulb and tract pass posteriorly in the olfactory sulcus of the frontal lobe and the olfactory groove of the anterior cranial fossa.

It divides into medial and lateral stria (anterior to the anterior perforated substance):

  • The lateral stria synapse at the primary olfactory cortex
  • The medial stria crosses the anterior commissure

It is the only sensory modality which is not relayed to the thalamus prior to synapsing at the cortex.

134
Q

Olfactory N: Vasculature

A

Arterial: ACA

Venous: Cavernous sinus

135
Q

Olfactory N: Relations

A
  • Superior: olfactory sulcus, anterior frontal lobe
  • Inferior: cribiform plate, olfactory mucosa
  • Medial: crista galli/flax, gyrus rectus
  • Lateral: Medial orbital gyrus
  • Anterior: Frontal sinuses
  • Posterior: Suprasellar cistern
136
Q

Olfactory N: Variants

A

Agenesis

137
Q

Optic N: Description

A

The optic nerve is the second cranial nerve.

Function: Special sensory – vision, carries visual information from the retina to optic radiations

138
Q

Optic N: Gross anatomy

A

Extension of the CNS with associated extension of the dura and CSF space.

Dividable into 4 segments:

  • Intraocular – within the retina
  • Intraorbital – within the orbit
  • Intracanalicular – exits through the tendinous ring runs through the optic canal superior to the ophthalmic artery
  • Intracranial – Runs the suprasellar cistern meeting at the optic chiasm

Nasal fibres decussate at the optic chiasm, temporal fibres do not.

2 optic tracts leave the chiasm coursing around the cerebral peduncles to the lateral geniculate body of the thalamus.

Superior (superior retina) and inferior (inferior retina) bundle arise from the lateral geniculate bodies.

Superior bundle -> superior calcarine sulcus. Inferior bundle to the inferior.

139
Q

Optic N: Arterial

A

Ophthalmic artery (and central retinal artery)

ACA and superior hypophyseal artery

140
Q

Optic N: Relations

A

Optic chiasm:

Posterior: the pituitary infundibulum and mamillary bodies

Superior: anterior perforated substance, hypothalmus

Lateral: middle cerebral arteries

Inferior: sella turcica, pituitary gland

141
Q

Optic N: Variants

A

1 – nerve adjacent to the sphenoidal sinus

2 – Nerve compresses the wall of the sphenoid sinus

3 – nerve courses through the sphenoid sinus

4 – lateral to the sphenoid and posterior ethmoid

142
Q

Occulomotor N: Description

A

The third cranial nerve.

Function: motor to the extra-occular muscles except lateral rectus and superior oblique, parasympathetic to the ciliary ganglion. Motor to the levator palpebrae superioris.

143
Q

Oculomotor N: Gross anatomy

A

Origin: Medial aspect of the cerebral peduncles, (from the oculomotor nucleus anterior to the periaqueductal grey and the Edinger-Westphal nucleus – parasymp to ciliary ganglion). In the basal/interpeduncular cistern.

Course:

  • Between the posterior cerebral artery and the superior cerebellar artery
  • Enters the cavernous sinus (most superior structure)
  • Enters the orbit via the superior orbital fissure

Divides into:

  • Superior division: runs above the optic nerve gives branches to SR and lavator palpabre superioris.
  • Inferior division: parasymp. To ciliary ganglion and the extraocular muscles except SO,LR,SR
144
Q

Oculomotor N: Vasculature

A

Arterial: opthlamic artery

Venous: Superior ophthalmic vein

145
Q

Oculomotor: Relations

A

Origin is superior to the pons

Runs between the posterior cerebral and superior cerebellar arteries

Most superior nerve in the lateral wall of the cavernous sinus, above trochlear

Enters the orbit within the tendinous ring

146
Q

Oculomotor: Variant

A

Origin may vary

Relation to arteries may vary

147
Q

Trochlear N: Description

A

The fourth cranial nerve.

Function: Motor to superior oblique

148
Q

Trochlear: Gross anatomy

A

Smallest diameter cranial nerve

Longest intracranial length

Only nerve to emerge posteriorly

Divided into:

  • Intraparenchymal portion
  • Cisternal portion
  • Cavernous portion
  • Orbital portion

Origin: trochlear nucleus, decussates, exits below the inferior colliculus

Course:

  • cisternal portion course through the ambient cistern, runs between the superior cerebellar artery and the posterior cerebral artery lateral to the oculomotor nerve
  • Cavernous portion pieces the dura posteriorly and courses through the lateral wall of the cavernous sinus
  • Enters the orbit through the superior orbital fissure outside of the tendinous ring
  • Orbital portion arches up and medially above superior rectus and superior levator palpebrae to innervate the superior oblique
149
Q

Trochlear N: Vasculature

A

Arterial:

Ophthalmic artery

Venous:

Ophthalmic vein

150
Q

Trochlear N: Relations

A
  • Origin inferior to the inferior colliculus
  • Runs between the superior cerebella and posterior cerebral arteries lateral to oculomotor
  • Runs beneath the oculomotor nerve and above the ophthalmic nerve in the wall of the cavernous sinus
151
Q

Trigeminal N: Description

A

The fifth cranial nerve

Function: Sensory information from the face, head and 2/3 anterior tongue and motor to the muscle of mastication plus mylohyoid (chin/jaw to hyoid) and tensor palatini.

152
Q

Trigeminal N: Gross anatomy

A

Origin: Three sensory and one motor nuclei of the trigeminal nerve within the brain stem

Exits at the lateral aspect of the pons

Course:

Anterior through the pre-pontine cistern

Enters Meckel’s cave forming the trigeminal ganglion

Dividing into:

  • Ophthalmic division
  • Maxillary division
  • Mandibular division
153
Q

Ophthalmic division of Trigeminal

A

Course:

  • Through the lateral wall of the cavernous sinus
  • Branches through the superior orbital fissure

Branches:

  • Fronatal
  • Lacrimal
  • Nasociliary

Supplies:

Sensation to the upper 1/3 of the face and cornea

154
Q

Maxillary division of Trigeminal

A

Course:

  • Through the lateral wall of the cavernous sinus
  • Through the foramen rotundum into the pterygopalatine fossa

Branches:

  • Zygomatic
  • Infraorbital
  • Greater and lesser palatine

Supplies:

Sensation to the middle 1/3 of the face

155
Q

Mandibular division of Trigeminal

A

Course:

  • Through the foramen ovale

Branches: Anterior and posterior divisions

Supplies:

  • Muscles of mastication
  • Sensation to the lower 1/3 of the face and TMJ
156
Q

Abducens: Description

A

The abducens nerve is the 6th cranial nerve.

Function: motor to the lateral rectus

157
Q

Abducens N: Gross anatomy

A

Divided into 4 parts:

  • Intraparynchymal
  • Cisternal
  • Cavernous
  • Orbital

Origin: Abducens nucleus, exits at the pontomedullary junction medial to the facial nerve

Course:

  • Ascending in the pre-pontine cistern between the pons and the clivus
  • Through Dorello’s canal
  • Pierces the dura inferior to the posterior clinoid process
  • Cavenous portion runs within the cavernous sinus between the internal carotid and the lateral wall
  • Enters the orbit through the superior orbital fissure within the tendinous ring

Terminates:

Lateral rectus

158
Q

Abducens N: Vasculature

A

Artery:

Ophthalmic artery

Vein:

Opthalmic vein

159
Q

Abducens: Relations

A
  • Origin is medial to the facial nerve origin
  • Runs in the cavernous sinus between the internal carotid is medial and the trochlear nerve is lateral
  • Enters the orbit within the tendinous ring
160
Q

Facial N: Description

A

The facial nerve is the seventh cranial nerve

Function: Motor to the muscles of facial expression, stapedius, taste to the anterior 2/3 of the tongue and parasympathetic to lacrimal, sublingual and submandibular glands.

161
Q

Facial N: Gross anatomy

A

Nuclei: Facial nerve nucleus, superior salivary nucleus, solitary nucleus

Origin: emerges from the pontomedullary junction lateral to the abducens nerve

Segments (I must learn to make expressions):

  • Intracranial – joined by nervus intermedius, travels in the cerebellopontine angle cistern
  • Meatal – Anterior superior quadrant of the internal auditory canal, above the falciform crest and anterior to Bill’s bar
  • Labyrinthine – courses superior to and between the cochlear and vestibule in the fallopian canal, terminates at the geniculate ganglion at the anterior genu
  • Tympanic – Passes posterior from the genu in the medial wall of the middle ear. Second genu posterior to the pyramidal eminence passing down into the mastoid segment
  • Mastoid – descending in the medial wall of the aditus ad antrum of the mastoid in the fallopian canal exiting via the stylomastoid foramen. Chorda tympani arises here (taste and secretomotor).
  • Extracranial:
  • Passes between the posterior belly of the digastric muscle and the stylohyoid muscle
  • Enters the parotid gland between the deep and superficial lobes, dividing into 5 branches
162
Q

Facial N: Branches

A
  • Temporal
  • Zygomatic
  • Buccal
  • Mandibular
  • Cervical
163
Q

Facial N: Arterial

A
  • Labyrinthine
  • Superficial petrosal
  • Stylomastoid arteries
164
Q

Vestibulocochlear N: Description

A

The eight cranial nerve.

Function: Innervation to the cochlea (hearing) to the vestibule (acceleration)

165
Q

Vestibulocochlear N: Gross Anatomy

A

Origin: Most lateral of the pontomedullary junction nerves

Course:

Passes lateral through the cerebellopontine angle to the internal acoustic meatus

Divides into:

  • Cochlear nerve
  • Superior and inferior divisions of the vestibular nerve
  • Nerve from the posterior semicircular canal

Divided in the internal acoustic meatus by Bill’s bar and the falciform crest

Cochlear nerve – sensory from the spiral ganglion

Vestibular nerve:

  • Superior div. – sensory from the superior and lateral semicircular canals and the urticle
  • Inferior div. – sensory from the saccule
  • Nerve from the posterior semicircular canal – as the name suggests
166
Q

Vestibulocochlear N: Relations

A

Origin is lateral to the origin of nervus intermedius and the facial nerve

167
Q

Vestibulocochlear N: Vasculature

A

Arterial supply:

Labyrinthine artery

Venous drainage:

Labyrinthine vein

168
Q

Glossopharyngeal N: Description

A

The ninth cranial nerve

Function:

  • Sensory to the tonsils, pharynx, middle ear and posterior third of the tongue
  • Taste from the posterior third of the tongue
  • Sensory from the carotid bodies
  • Parasympathetic to the parotid gland via the otic ganglion
  • Motor to stylopharyngeus
169
Q

Glossopharyngeal N: Course

A

Origin: lateral medulla from the post olivary sulcus

Nuclei:

  • Inferior salivary nucleus
  • Solitary nucleus
  • Glossopharyngeal nucleus

Course:

  • laterally across the flocculus
  • Leaves the skull through the pars nevosa of the jugular foramen
  • Presents two ganglia superior and inferior
  • Passes between the internal jugular vein and internal carotid artery
  • Descends anterior to the internal carotid artery beneath the styloid process
  • At the lower border of stylopharyngeus it turns forward and forms an arch on the middle pharyngeal constrictor muscle
  • Passes under hyoglossus
  • Terminates at the palatine tonsils
170
Q

Glossopharyngeal N: Branches

A

Too many cats please train (the) little shits

  • Tympanic
  • Muscular
  • Carotid
  • Pharyngeal
  • Tonsillar
  • Lingual
  • Sinus
171
Q

Glossopharyngeal N: Relations

A
  • Origin is superior to the vagus origin
  • Pars nervosa is the anterior part of the jugular foramen
172
Q

Vagus N: Description

A

The 10th cranial nerve. Latin for wandering nerve due to its long wandering course. From brain to the abdomen.

Function: Bulk of the parasympathetic to the gastrointestinal system and heart. Complex mixed sensory, motor and parasympathetic nerve.

173
Q

Vagus N: Gross Anatomy

A

Origin: Multiple rootlets from the posterolateral sulcus of the medulla

Nuclei:

  • Nucelus ambiguous
  • Dorsal vagal nucleus
  • Solitary tract
  • Spinal trigeminal nucleus
174
Q

Vagus N: Course

A
  • Travels around the medulla
  • Exits the skull via the pars vascularis of the jugular foramen
  • Presents superior and inferior ganglia
  • Descends in the carotid sheath between the internal jugular vein and internal/common carotid
  • Passes anterior to the subclavian arteries to enter the superior thoracic outlet
  • Both sides descend in the lateral aspects of the mediastinum posterior to the hilum of the lungs
  • Both nerve enter the abdomen through the oesophageal hiatus
  • The left nerve becomes the anterior vagal plexus
  • The right nerve becomes the posterior vagal plexus
175
Q

Vagus N: Major Branches

A
  • Auricular nerve
  • Pharyngeal nerve
  • Carotid body branches
  • Superior and recurrent laryngeal nerves
  • Superior and inferior cardiac nerves
  • Anterior and posterior bronchial nerves
  • Oesopheal, coeliac and hepatic plexi
176
Q

Vagus N: Relations

A
  • Origin is below the origin of the glossopharyngeal nerve
  • The pars vascularis is the posterior part of the jugular foramen
  • Runs anterior to scalenus anterior and posterior to sternocleidomastoid
177
Q

Accessory N: Description

A

The spinal accessory nerve, also called accessory nerve, is the eleventh cranial nerve (CN XI) and is composed of two parts, the cranial part and the spinal part.

Function: motor to trapezius and sternocleidomastoid

178
Q

Cranial Accessory N: Gross anatomy

A

Cranial part:

  • Fibre arise from cells of the nucleus ambiguous and emerge from either side of the medulla below the Vagus nerve
  • It runs anterior and joins the spinal portion
  • Passes through the jugular foramen
  • Separates from the spinal portion and joins the Vagus at the ganglia nodusum
  • Probably contributes to innervation of the uvula and levator vei palatine
179
Q

Spinal Accessory N: Gross Anatomy

A
  • Fibre arise from the ventral horn between C1 to C5 forming a trunk
  • The trunk ascends entering the skull through the foramen magnum join the cerebral part to exit via the jugular foramen
  • Leaves the cranial part
  • Descends behind SCM
  • Pierces SCM giving innervation
  • In the posterior triangle it forms a plexus with the cervical nerves innervating the trapezius
180
Q

Accessory N: Vasculature

A

Arterial:

Branches of the vertebral arteries

Ascending cervical

Dorsal scapula

Venous drainage:

Clival venous plexus

Internal jugular

Dorsal scapula

181
Q

Hypoglossal N: Description

A

The 12th cranial nerve. Paired bilateral motor nerves.

Function:

  • Meningeal branches innervate the dura of the posterior cranial fossa
  • Supply motor to all the muscle of the tongue except for palatoglossus (supplied by vagus).
182
Q

Hypoglossal N: Gross anatomy

A

Origin:

Emerges from the medulla laterally between the pyramid and olive as a number of rootlets

Course:

  • Rootlets join to form two roots on each side
  • The two roots leave the cranial fossa passing anteriorly through the hypoglossal canal located between the occipital condyle and the jugular tubercle of the occipital bone
  • The roots join to for a single nerve within the canal on each side
  • C1 branches join with the nerve at this point
  • Passes between the internal jugular and the internal carotid artery
  • The occipital artery loops around it
  • It then runs anterior, lateral to the lingual artery
  • Gives of branches when it reaches hyoglossus
183
Q

Hypoglossal N: Vasculature

A

Arterial supply:

  • Lingual artery

Venous drainage

  • Internal jugular vein
  • Lingual veins
184
Q

Hypoglossal N: Relations

A
  • Origin is between the olive and the pyramid, inferior to the vagus origin and superior to the spinal accessory origin
  • The hypoglossal canal is superior to the occipital condyles
  • Nerve runs anteriorly lateral to the lingual artery
185
Q

Medulla Oblongata

A
  • Medulla oblongata is the most caudal part of the brainstem and is between the pons inferiorly and spinal cord superiorly
  • Contains the vital autonomic cardiovascular and respiratory centers controlling heart rate, blood pressure, and breathing
  • Medulla is separated into two main parts:
    • ventral medulla which contains the olive, pyramidal tracts, and CN 9-12 rootlets
    • tegmentum (dorsal) medulla which contain the CN nuclei and white matter tracts
  • Ventral medulla
    • pyramids are paired structures located at the medial aspect of ventral medulla and flank the anterior median fissure
      • contains the the corticospinal tracts
      • corticospinal tracts decussate
    • olivary bodies are paired structures located at lateral aspect of ventral medulla
      • separated from the pyramids by an anterolateral sulcus
      • also a post-olivary sulcus lateral to the olivary bodies
      • olivary bodies contain the superior and inferior olivary nuclei
    • anteriorly there is an anterior median fissure
  • Dorsal medulla
    • posterior median sulcus and more lateral posterolateral sulcus
      • between these sulci are the fasciculus gracilis and nuclei forming gracilis tubercle at the midline
      • fasciculus cuneatus and nuclei forming cuneate tubercle more laterally
    • superior dorsal aspect of medulla forms the floor of the inferior 4th ventricle
    • inferior cerebellar peduncle
    • inferiorly surrounded by the cisterna magna
  • Embryology: myelencephalon aspect of the rhombencephalon (or hindbrain) becomes the medulla
186
Q

Medulla oblongata: Relations

A

Anterior: basilar part of the occipital bone

Posterior: 4th ventricle, cerebellum, cisterna magna

Hypoglossal nerve rootlets arise anterior to the olive

Glossopharyngeal, vagus and accessory nerve fibres emerge posterior to the olives

CN 6-8 arise between pons and medulla

187
Q

Medulla oblongata: Vasculature

A

Arterial supply:

  • Anterior: vertebral arteries, anterior spinal artery
  • Posterior: PICA

Venous drainage:

  • Anterior: inferior petrosal sinus
  • Posterior: occipital sinus

Anatomy (11 decks)

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