Anatomy 🫀 Flashcards
what is the 4th ventricle?
- Cavity of hind brain
Site of 4th ventricle
- in front of the cerebellum, behind pons & upper half of the medulla
Shape of 4th ventricle
diamond shape
angles of 4th ventricle
- Upper angle continuous with aqueduct of sylvius.
- Lower angle continuous with central canal
- Lateral angels form the lateral recess of the 4th ventricle
Boundaries of 4th ventricle
- Lateral
- roof (post wall)
- Floor (ant wall)
Lateral borders of 4th ventricle
Superior: superior cerebellar peduncle
Inferior: inferior cerebellar peduncle & gracile and cuneate
Middle: lateral recess
Roof (Post wall) of 4th ventricle
- Sup. Medullary velum.
- Inf. Medullary velum.
- Middle: part of cerebellum
Flor (Anterior wall) of 4th ventricle
- Upper pontine part
- Lower medullary part
- Intermdiate zone which is formed by stria medullaris of 4th ventricle
Contents of anterior wall of pontine part of 4th ventricle
- Medial eminence & facial colliculus: overlies abducent nucleus.
- Vestibular area: overlies vestibular nuclei.
- Sulcus limitans (superior fovae)
Contents of anterior wall of medullary part of 4th ventricle
- Sulcus limitans (inferior fovea) divides medullary part into 3 trigons
1. Hypoglossal triangle (H)
2. Vagal triangle (Vg)
3. Vestibular area (Vs) - area postrema.
- stria medullaris of 4th ventricle.
what are cranial nerve nuclei in floor of 4th ventricle?
Hypoglossal trigone: contains hypoglossal nucleus
Vagal trigone: contains dorsal motor nucleus of vagus
Vestibular trigone: contains medullary and pontine vestibular nuclei
Facial colliculus: cantains abducent nucleus
Communications of 4th ventricle
- With 3rd ventricle through cerebral aqueduct of sylvius
- With centeral canal of spinal cord through lower angle
- With subarachinoid space through foramen of Magendie& foramina of Luschka
Site of choroid plexus of 4th ventricle
- it is attached to the inferior medullary velum.
Shape of choroid plexus of 4th ventricle
- T shaped it has stem attached to he velum and 2 lateral arms extend laterally into the lateral recess.
Arterial supply of choroid plexus of 4th ventricle
PICA
what separates the cerebellum from cerebrum?
tentorium cerebelli
what separates the cerebellum from pons and medulla?
4th ventricle
Gross feature of cerebellum
- It is formed of vermis (Superior & Inferior) and two cerebellar hemispheres
- It has two notches Ant. surround the brainstem & post Contain the falx cerebelli
Notches of cerebellum
- It has two notches Ant. surround the brainstem & post Contain the falx cerebelli
what are cerebellar peduncles? and what do they connect?
Superior cerebellar peduncle: Connects midbrain & Cerebellum
Middle cerebellar peduncle: Connects pons & Cerebellum.
Inferior cerebellar peduncle: Connects medulla & Cerebellum.
what are the fissures of Cerebellum?
- Horizontal fissure
- Primary fissure
- osterolateral fissure (uvulo-nodular fissure)
Significance of Horizontal fissure
- divides the cerebellum into superior & inferior surfaces.
Significance of Primary fissure
- extends on the superior surface
- It separates the anterior lobe from the posterior lobe.
Significance of Posterolateral fissure (uvulo-nodular fissure)
- extends on the inferior surfaces separating nodule from the uvula .
Anatomical divisions of cerebellum
It is divided by 1ry fissure & posterolateral fissure into:
- Anterior lobe
- Posterior lobe
- Folliculonodular lobe
Longitudinal divisions of cerebellum
According to connections of the deep cerebellar nuclei
- Vermal zone projects to fastigial nucleus
- Paravermal zone Projects to globose and emboliform nuclei
- Lateral zone projects to dentate nucleus
Functional divisions of cerebellum
- Archicerebellum (vestibulocerebellum)
- Paleocerebellum (spinocerebellum)
- Neocerebellum (cerebrocerebellum)
Position of the diencephalon
- It is located between the cerebral hemisphers and the midbrain.
Boundaries of diancephalon
- Superiorly
- Anteriorly
- Medially
- Inferiorly
- Posteriorly
- Laterally
Superior boundaries of diancephalon
- Body of the fornix
- Lateral ventricle
Inferior boundaries of diancephalon
- Optic chiasma
- Tuber cinereum
- Infundibulum of pituitary gland
Anterior boundaries of diancephalon
- Anterior commissure
- Lamina terminalis
Posterior boundaries of diancephalon
- Habenular nucleus
- Pineal gland
- Posterior commissure
Medial boundaries of diancephalon
- Third ventricle
Lateral boundaries of diancephalon
- Internal capsule
- Lentiform nucleus
Divisions of diancephalon
From PPT
Function of the Diencephalon
Thalamus:
- receives all sensations (except olfaction) and projects them to the sensory areas of the brain.
Hypothalamus:
- is the principal autonomic and endocrinal center of the brain.
Subthalamus:
- is one of the motor nuclei that regulate muscle movement.
Epithalamus:
- is formed of Stria medullaris thalami (limbic system), Habenular nucleus (limbic system), Pineal gland (sleep) and Posterior commissure (upward gaze).
Site of Choroid plexus of 3rd ventricle
- roof of the 3rd ventricle.
Arterial supply of Choroid plexus of 3rd ventricle
posterior choroidal artery.
what is 3rd ventricle?
- It is the cavity of the diencephalon.
Location of 3rd ventricle
- It is located in the midline between two thalami.
Site of choroid plexus of 3rd ventricle
- projects downward from the roof.
Shape of choroid plexus of 3rd ventricle
- two vascular ridges, one on each side of the midline.
Arterial supply of choroid plexus of 3rd ventricle
posterior choroidal artery.
Communications of 3rd ventricle
1- with the lateral ventricle : through interventricular
foramen of Morno.
2- with 4th ventricle : through cerebral aqueduct of sylvius.
what does each cerebral hemisphere contain?
3 (Poles, Borders, Surfaces)
4 (Major sulci, Lobes)
Poles of each cerebral hemisphere
- Frontal
- Temporal
- Occipital
Borders of of each cerebral hemisphere
- Superomedial border
- Inferomedial border
- Inferolateral border
Surfaces of of each cerebral hemisphere
- Lateral (superolateral) surface
- Medial surface
- Inferior surface
what are the parts of the inferior surface?
- Orbital part
- Tentorial part
what divides the inferior surface?
It is divided by the lateral sulcus into two parts
Parts of inferior surface
Orbital part: lies on the roof of the orbit.
Tentorial part: lies on the tentorium cerebelli.
what are major sulci of each cerebral hemisphere?
- Central sulcus.
- Lateral sulcus.
- Calcarine sulcus.
- Parieto-occipital
what does lateral sulcus consist of?
It consists of a short stem & 3 rami:
- Anterior ramus.
- ascending ramus.
- posterior ramus.
what is The area of cerebral cortex at the bottom of the lateral sulcus?
Insula
what are sulci of lateral Surface?
- Central sulcus.
- Precentral sulcus.
- Postcentral sulcus.
———-
- Lateral sulcus
- Two frontal sulci
- Two temporal sulci
———
- Intraparietal sulcus.
- Parieto-occipital sulcus.
- Calcarine sulcus.
- Sulcus lunatus.
what are parts of lateral sulcus?
(stem & 3 rami)
- Anterior ramus.
- ascending ramus.
- posterior ramus.
what are two frontal sulci of lateral Surface?
- Superior frontal sulcus
- Inferior frontal sulcus
what are two temporal sulci of lateral Surface?
- Superior temporal sulcus.
- Inferior temporal sulcus.
what are gyri of lateral Surface?
- Precentral gyrus.
- Postcentral gyrus.
———
- Three frontal gyri
——-
- Three temporal gyri
———–
- Two parietal gyri
what are three frontal gyri of lateral Surface?
- Superior frontal gyrus.
- Middle frontal gyrus.
- Inferior frontal gyrus:
what divides inferior frontal gyrus?
Divided by the anterior & ascending rami of the lateral sulcus into 3 parts:
- Orbital part.
- Triangular part.
- Opercular part.
Parts of inferior frontal gyrus
- Orbital part.
- Triangular part.
- Opercular part.
what are three temporal gyri of lateral Surface?
- Superior temporal gyrus.
- Middle temporal gyrus.
- Inferior temporal gyrus.
what are 2 parital gyri of lateral Surface?
- Superior parietal lobule.
- Inferior parietal lobule
what is Inferior parietal lobule divided
into?
- Supramarginal gyrus.
- Angular gyrus.
what are cortical areas? and what do they contain? (In brief)
Frontal lobe contains:
- Motor areas
- Personality center
The other 3 lobes contain:
- Primary sensory areas.
- Sensory association areas
what are motor areas of frontal lobe?
- Primary motor area (area 4)
- Premotor area (area 6)
- Frontal eye field area (area 8)
- Motor speech area (Broca’s area, areas 44 & 45)
Site of Primary motor area (area 4)
- In the precentral gyrus &
anterior part of the paracentral lobule.
Representation of Primary motor area (area 4)
- Opposite half of body is represented upside down.
Function of Primary motor area (area 4)
- Initiation of highly skilled
fine movements.
what does a lesion in Primary motor area (area 4) cause?
- Contralateral hemiplegia with
all signs of upper motor neuron lesion.
Site of Premotor area (area 6)
- Anterior to the primary motor area.
Function of Premotor area (area 6)
- Gross or Stereotyped movements of groups of muscles via connections with the basal ganglia.
what does a lesion in Premotor area (area 6) cause?
Apraxia: (difficulty in performing a learned movement without paralysis)
Site of Frontal eye field area (area 8)
- Middle frontal gyrus.
Function of Frontal eye field area (area 8)
- Horizontal movement of both eyes to the opposite side.
What does a lesion in Frontal eye field area (area 8) cause?
- Ipsilateral deviation of both eyes.
Site of Motor speech area (Broca’s area, areas 44 & 45)
- Inferior frontal gyrus of the dominant hemisphere: Opercular & triangular gyri.
Function of Motor speech area (Broca’s area, areas 44 & 45)
- Coordinates actions of the muscles used in speech (lips, tongue & vocal cords).
what does a lesion in Motor speech area (Broca’s area, areas 44 & 45) cause?
Motor aphasia:
- Aphasia is paralysis of the speech.
Lesion in hemisphere (right):
- No effect.
Personality centre in frontal lobe
- Personality Center Personality Center (Areas 9, 10, 11 & 12)
Site of Personality centre
frontal pole.
Function of Personality centre
Makeup of the personality.
what does a lesion in Personality centre cause?
Loss of personality:
- Patients neglect their appearance.
- Inappropriate judgmental behavior.
- No appreciation to any social behavior.
what are sensory areas?
- General (somatic) sensory area (areas 3, 1, 2)
- Somatosensory association area (areas 5, 7 & 40)
- Primary gustatory area (taste area, area 43)
- Primary auditory area (Heschl’s area, areas 41 & 42)
- Auditory association area (Wernicke’s area, area 22)
- Primary visual area (area 17)
- Visual association areas (areas 18, 19 & 39)
- Sensory speech (language) areas (present in the dominant hemisphere)
Site of General (somatic) sensory area (areas 3, 1, 2)
- Postcentral gyrus & posterior part of paracentral lobule.
Function of General (somatic) sensory area (areas 3, 1, 2)
- Perception of all sensations
from the opposite side of the body &face
Representation of General (somatic) sensory area (areas 3, 1, 2)
- Opposite half of body is represented upside down.
What does a lesion in General (somatic) sensory area (areas 3, 1, 2) cause?
- Loss of all sensations on the opposite side of the body & face followed by crude awareness of pain,temperature and touch after recovery from the acute stage.
Site of Somatosensory association area (areas 5, 7 & 40)
(areas 5,7):
- Superior parietal lobule.
(Area 40):
- Supramarginal gyrus
Function of Somatosensory association area (areas 5, 7 & 40)
Stereognosis
- Interpretation of senses received in the general sensory area (recognition of size, shape & texture of objects)
what does a lesion in Somatosensory association area (areas 5, 7 & 40) cause?
Astereognosis
- Inability to recognize objects by the sense of touch and pressure with eyes closed.
Site of Primary gustatory area (taste
area, area 43)
- Lower end of the general sensory area.
Function of Primary gustatory area (taste area, area 43)
- Discrimination of different taste sensations.
Site of Primary auditory area (Heschl’s area, areas 41 & 42)
- Middle of the superior temporal gyrus.
Function of Primary auditory area (Heschl’s area, areas 41 & 42)
- Perception of sounds from the 2 ears, mainly from the opposite ear.
Lesion in Primary auditory area (Heschl’s area, areas 41 & 42)
- Bilateral diminution of hearing mainly on the opposite side.
Site of Auditory association area
(Wernicke’s area, area 22)
- Posterior part of the superior temporal gyrus.
Function of Auditory association area
(Wernicke’s area, area 22)
- understands the spoken language.
- It is a sensory speech area.
Lesion in Auditory association area
(Wernicke’s area, area 22)
Auditory agnosia:
- inability to recognize sounds.
Sensory aphasia:
- inability to understand the spoken language.
Site of Primary visual area (area 17)
- Lips of calcarine sulcus (above and below calcarine sulcus).
Function of Primary visual area (area 17)
- Perception of light.
Lesion in Primary visual area (area 17)
- Contralateral homonymous hemianopia with macular sparing.
Site of Visual association areas
(areas 18, 19 & 39)
Areas 18, 19:
- Above and below primary visual area.
Area 39:
- In angular gyrus.
Function of Visual association areas
(areas 18, 19 & 39)
Areas 18, 19:
- Recognition of what we see.
Area 39:
- understand written language.
Lesion in Visual association areas
(areas 18, 19 & 39)
Visual agnosia:
- inability to recognize what we see.
Alexia & agraphia:
- inability to read & write (Lesion in angular gyrus).
Sensory speech (language) areas (present in the dominant hemisphere)
- Sensory speech areas.
- Motor speech area (Broca’s area).
Significance of connection between The sensory speech areas are connected with the motor speech
area (Broca’s area)
- to answer a spoken or a written question.
Site of Sensory speech (language) areas (present in the dominant hemisphere)
Wernicke’s area (Area 22):
- In superior temporal gyrus.
(area 39):
- In angular gyrus.
(Area 40):
- In supramarginal gyrus.
Functions of Sensory speech (language) areas (present in the dominant hemisphere)
Wernicke’s area (Area 22):
- Understands spoken language
(area 39):
- Understands written language
(Area 40):
two main functions
- Recognition of size, shape & texture of objects (Stereognosis).
- Recognition of the individual’s body image (left from right side).
lesion in Sensory speech (language) areas (present in the dominant hemisphere)
- In the dominant hemisphere
- In the non-dominant hemisphere:
lesion in Sensory speech (language) areas (present in the dominant hemisphere) in dominant hemisphere
- Lesion in Wernicke’s area
- Lesion in the angullar gyrus
- Lesion limited to the supramarginal gyrus
Lesion in Wernicke’s area in dominant hemisphere
Auditory agnosia: inability to recognize sounds.
Sensory aphasia: inability to understand spoken langua
Lesion in the angullar gyrus in dominant hemisphere
inability to understand written language
Alexia: inability to read.
Agraphia: inability to write.
Lesion limited to the supramarginal gyrus in dominant hemisphere
Tactile agnosia (astereognosis):
- inability to recognize objects by the sense of touch with the eyes closed.
Unilateral neglect:
- inability to recognize his left from right side.
Lesion in Sensory speech (language) areas (present in the dominant hemisphere) in non-dominant hemisphere
- Disturbances in drawing
what are sulci of Medial Surface?
- Callosal sulcus.
- Cingulate sulcus.
- Marginal sulcus.
- Subparietal sulcus.
- Calcarine sulcus.
- Parieto-occipital sulcus.
what are gyri of Medial Surface?
- Cingulate gyrus
- Lingual gyrus.
- Cuneus.
- Precuneus.
- Paracentral lobule.
Cortical areas in Medial Surface
Primary visual area (area 17):
- lips of the calcarine sulcus.
Visual association areas (areas 18 & 19):
- on either side of the primary visual area.
Extension of the primary motor & general sensory areas:
- In the anterior & posterior parts of the paracentral lobule, respectively.
Prefrontal cortex (personality center):
- In the frontal pole.
parts of Inferior Surface
- Orbital surface
- Tentorial surface
Sulci in Orbital surface
- Olfactory sulcus.
- Orbital sulcus (H-shaped)
Gyri in Orbital surface
- Gyrus rectus: medial to the olfactory sulcus.
- Orbital gyri.
Sulci in Tentorial surface
- Collateral sulcus.
- Rhinal sulcus.
- Occipitotemporal sulcus.
gyri in tentorial surface
- Parahippocampal gyrus.
- Uncus (the anterior end of the parahippocampal gyrus).
- Occipitotemporal gyrus (fusiform gyrus): Between collateral & occipitotemporal sulci.
Cortical areas of Inferior Surface
- Primary olfactory area
- Olfactory association area (area 28)
- Face recognition area (area 37)
Site of Primary olfactory area
Uncus
lesion in uncus
olfactory hallucinations.
Site of Olfactory association area (area 28)
- anterior part of parahippocampal gyrus & the amygdaloid nucleus.
Function of Olfactory association area (area 28)
- recognition of different odors
Site of Face recognition area (area 37)
- Posterior part of fusiform gyrus.
Lesion in Face recognition area (area 37)
Prospagnosia: inability to recognize familiar faces.
compenents of limbic system
a) Nuclei
b) Fibers
nuclei (gray matter) of limbic system
- Limbic lobe (Cingulate gyrus, Parahippocampal gyrus, Uncus).
- Hippocampal Formation (Hippocampus, Dentate gyrus).
- Hypothalamus (Mamillary body)
- Anterior & medial thalamic nuclei
- Septal nuclei
- Amygdaloid
- Habinular nucleus
Fibers (white matter) connecting the nuclei of limbic system
- Cingulum
- Fornix (Fimbria, Crus, Body, Anterior column)
- Mamillothalamic Tract .
- Anterior Thalamic Radiation
- Stria Terminalis
- Stria Medullaris Thalami
Cingulum
- fiber of the limbic lobe
Fornix (Fimbria, Crus, Body, Anterior column)
- connect hippocampus
& mammillary body
Mamillothalamic Tract
- from mammillary body to anterior thalamic nucleus.
Anterior Thalamic Radiation
- from anterior thalamic nucleus to the cingulate gyrus & from medial thalamic nucleus to prefrontal cortex.
Stria Terminalis
- from amygdaloid nucleus to septal area.
Stria Medullaris Thalami
- from septal area to habinular nucleus
what are nerve fibers of white matter?
Commisural fibers:
- connect the same cortical areas of two cerebral hemispheres.
Association fibers:
- connect cortical areas in the same cerebral hemisphere.
Projection fibers:
- connect the cerebral cortex with subcortical areas.
types of Commissural fibers
1- Corpus callosum.
2- Anterior commissure
3- Posterior commissure
4- Hippocampal commissure: connect 2 fornices and 2 hippocampi
5- Habenular commissure:Connect 2 habenular nulei
function of corpus callosum
- Transfere information between 2 hemisphere
what is the rostrum of corpus callosum continous with?
continous with lamina terminalis
what does the fibers of genu of corpus callosum form?
- its fibers form forceps minor that connect the two frontal lobes.
what does the body of corpus callosum form?
Form radiation of corpus callosum posterior fibers called tapetum connect two temporal lobes
what does the splenium of corpus callosum form?
- its fibers form forceps major that connect the two occipital lobes.
Blood supply of Corpus Callosum
- Supplied by Anterior cerebral artery .
- Splenium may supplied by posterior cerebral artery.
Lesion of corpus callosum
Callosal Apraxia:
- The language and memory processes not be accessible to non dominant hemisphere cause left sided disorders
Function of Anterior commisure
- Anterior commissure: connect the two temporal lobes
Function of posterior commisure
Connects:
- two superior colliculi
- the pretectal nucleus and Edinger Westiphal N for bilateral light reflex.
- Two occulomotor nuclei for upward gaze
function of association fibers
- Connect one cortical area with another area in same cortical hemisphere
types of association fibers
- Short association fibers connect adjacent cortical areas
- Long association fibers connect distant cortical areas
examples of association fibers
- Superior longitudinal Fasciculus arcuate fasciculus Connect 4 lobes together
- Inferior longitudinal Fasciculus Connect occipital lobe with temporal lobe
- Uncinate Fasciculus Connect frontal lobe with temporal lobe
- Cingulum (limbic lobe) Connect cingulate gyrus with parahippocampal gyrus end in uncus
function of projection fibers
- connect the cerebral cortex with subcortical areas. Form a compact bundle called internal capsule.
types of projection fibers
- Ascending projection fibers as thalamocortical fibers
- Descending projection fibers as corticospinal and corticobulbar fibers
Components of the basal ganglia
- Corpus Striatum
- Amygdaloid nucleus
- Claustrum
what is corpus striatum formed of?
Caudate nucleus: head, body & tail.
Lentiform nucleus: putamen & glabus pallidus.
what is amygdaloid nucleus functionally part of?
functionally, it is a part of the limbic system.
Shape of Caudate nucleus
C shaped
What is Caudate nucleus formed of?
formed of head, body & tail.
what is The head of caudate separated from the lentiform nucleus by?
- by the anterior limb of internal
capsule.
what is The body of caudate separated from the thalamus by?
thalamostriate vein and stria terminalis.
Relations of caudate and amygdaloid to the lateral ventricle
- Head of caudate forms the lateral wall of the anterior horn of the lateral ventricle.
- Body of caudate lies the floor of the central part of the lateral ventricle.
- Tail of caudate and amygdaloid lie the roof of the inferior horn of the lateral ventricle.
what is Lentiform nucleus formed of?
formed of putamen (lateral part) & glabus pallidus (medial part).
Relations of Lentiform nucleus
Medially: internal capsule
- Anterior limb: separating it from the head of caudate.
- Posterior limb: separating it from the thalamus.
Laterally:
- external capsule separating it from the claustrum.
Inferiorly:
- related to amygdaloid nucleus & anterior commissure.
Definition of internal capsule
- A band of projection fibers
Parts of internal capsule
Anterior Limb: between head of caudate and lentiform
——–
Genu: opposite the apex of lentiform
———-
Posterior Limb:
Lenticulothalamic part: between lentiform and thalamus
Reterolenticular part: behind lentiform
Sublenticular part: below lentiform
Fiber content of the internal capsule
- Anterior limb
- Genu
- Posterior limb
Fiber content of Anterior limb
Anterior thalamic radiation: From anterior & mediodorsal thalamic nuclei, to the frontal cortex.
Frontopontine fibers: That project to pontine nuclei, in the basal part of the Pons.
Fiber content of Genu of internal capsule
Corticobulbar fibers.
Fiber content of posterior part of internal capsule
- Lenticothalamic part
- Retrolentiular part
- sublenticular part
fiber content of Lenticothalamic part
- Corticospinal fibers.
- Thalamocortical.
- Frontorubral.
- Main sensory (superior thalamic ) radiation, from the ventral posterior nucleus to the primary somatosensory cortex.
Fiber content of Retrolentiular part
- contains posterior thalamic radiation (optic radiation & fibers from pulvinar to the sensory association areas).
Fiber content of sublenticular part
- contains Auditory radiation & nonfrontopontine fibers.
Revise blood supply from PPT (VIP)
what is the lateral ventricle?
- It is the cavity of the cerebral hemisphere.
shape and lining of lateral ventricle
- C shaped lined with ependyma and filled with CSF.
parts of lateral ventricle
1) Anterior horn.
2) Body.
3) Posterior horn.
4) Inferior horn.
relation of anterior horn of lateral ventricle
PPT
relation of body or central part of lateral ventricle
PPT
relation of posterior horn of lateral ventricle
PPT
relation of inferior horn of lateral ventricle
PPT
The lateral ventricle communicates with the 3rd ventricle through……
interventricular foramen of Monro.
The choroid plexus of the lateral ventricle is attached to…..
body and inferior horn of lateral ventricle
