Anatomy Flashcards
1-53 Anatomy of Orbital Contents 54-90 Visual Pathway 91-156 Structure of Eyeball 157-241 The Limbic System and Hypothalamus 242-318 Anatomy of the Thalamus 319-349 Anatomy of the Basal Ganglia 350-396 Meninges and Ventricle of the Brain 397-466 Anatomy of the Cerebellum 467-519 Blood Supply of the Brain 520-617 Organization of Cerebrum I
What bones contribute in forming the orbital margin?
Frontal
Maxillary
Zygomatic
What structures make up the roof of the orbital cavity?
Frontal bone
Lesser wing of sphenoid bone
What structures make up the lateral walls of the orbital cavity?
Zygomatic bone
Greater wing of sphenoid bone
What structures make up the medial wall of the orbital cavity?
Frontal process of maxilla
Lacrimal bone
Orbital plate of ethmoid bone
What structures make up the floor of the orbital cavity?
Zygomatic bone
Maxillary bone
Palatine bone
Where is the supraorbital notch found?
On the frontal bone, on the roof of orbital cavity
What is the superior orbital fissure?
Bony aperture that allows communication between cavernous sinus and the apex of the orbit
What structures pass through the Superior orbital fissure?
CN III [oculomotor nerve]
CN IV [trochlear nerve]
CN V [trigeminal nerve]
CN VI [abducens nerve]
Superior ophthalmic vein
What foramen is found on the medial wall?
Anterior ethmoidal foramina
Posterior ethmoidal foramina
Lacrimal groove
What foramen is found on the floor of the orbital cavity?
Infraorbital groove
Infraorbital foramen
Inferior Orbital fissure
What structures form the fibrous skeleton of the eyelid?
Tarsal plate
Orbital septum
Canthus medial ligament
Canthus lateral ligament
Describe the structure of the periorbital fascia
Posteriorly continuous with periosteum lining the interior of the skull / endosteal layer of the dura mater
Anteriorly continuous with periosteum covering external surface of skull
What is bulbar conjunctiva?
Thin, moist transparent membrane covering the cornea
Describe the structure of the bulbar conjunctiva
Reflects posterior surface of eyelid, forming palperbra conjunctiva
What does the palperbra conjunctiva form?
Superior and inferior fornices
What covers the inner surface of the eyelids?
Palpebral conjunctiva
What structure reinforces the eyelid
orbicularis oculi
What structures make up the lacrimal apparatus?
Lacrimal punctum
Lacrimal canaliculus
Lacrimal sac
Nasolacrimal duct
Inferior nasal meatus
What is the origin of the levator palpebra superioris?
Lesser wing of sphenoid bone
What is the insertion of the levator palpebra superioris?
Skin of upper eyelid
What is the innervation of the levator palpebra superioris?
Superior branch of oculomotor nerve
Sympathetic fibers [innervates smooth muscle portion]
What is the origin of Muller’s muscle?
Superior tarsal plate
What muscles are implicated in ptosis and why?
Dysfunction of the muscles or their nerve supplies
Levator palpebrae superioris
Muller’s [superior tarsal] muscle
What is the origin of the recti muscles?
Common tendinous ring, at the junction of the superior and inferior orbital fissure
What is the insertion of recti muscles?
Posterior to corneal-sclera junctions
What nerve innervates the recti muscles
All supplied by oculomotor
[Except lateral rectus is innervated by abducens nerve]
What is the origin of the superior oblique muscle?
Body of sphenoid body
What is the origin of the inferior oblique muscle?
Maxilla
What is the insertion of the superior oblique muscle?
sclera at posterosuperior aspect of the lateral side of the orbit
What is the insertion of the inferior oblique muscle?
Sclera at the posteroinferior aspect of the lateral side of the orbit
What nerve innervates the superior oblique muscle?
Trochlear nerve
What nerve innervates the inferior oblique muscle?
Oculomotor nerve
What are the actions of the Superior oblique muscle?
Abduction, depression and Intorsion
What are the actions of the Inferior oblique muscle?
Abduction, elevation, and extorsion
What are the actions of the inferior rectus muscle?
Adduction, depression and extorsion
What are the actions of the superior rectus muscle?
Adduction, elevation and intorsion
What muscles elevate and depress the eyes as it’s in an adducted position?
Elevates: Inferior oblique
Depresses: Superior oblique
What is the course of the ophthalmic artery?
1st branch of the ICA as it emerges from the cavernous sinus
What are the branches of the ophthalmic artery?
Central artery of retina
Ciliaries arteries
Lacrimal artery
Muscular arteries
5 terminal branches:
[Supraorbital
Supratrochlear
Dorsal nasal
Anterior ethmoidal artery
Posterior ethmoidal artery]
Describe the course of the superior ophthalmic vein
Anastomoses with facial vein, exits through superior orbital fissure and ends in cavernous sinus
Describe the course of the inferior ophthalmic vein
Starts as plexus on orbital floor, communicates with pterygoid plexus through the inferior orbital fissure and ends in:
[Superior ophthalmic vein
Cavernous sinus ]
Describe the course of the central vein
Enters cavernous sinus or joins ophthalmic veins
What are the branches of the ophthalmic division?
Frontal nerve
Lacrimal nerve
Nasociliary nerve
What are the divisions of the frontal nerve?
Supratrochlear nerve
Supraorbital nerve
What does the lacrimal nerve innervate?
Sensory innervation to lacrimal gland
Cutaneous innervation to superior eyelid
What are the branches of the nasociliary nerves?
Anterior ethmoidal
Posterior ethmoidal
Long ciliary nerve
Infratrochlear nerve
What does the long ciliary nerve innervate?
Sensory innervation to eyeball
Sympathetic innervation to dilator pupillae muscle
What does the nasociliary nerve innervate?
Sensory root to ciliary ganglion (sympathetic fibers)
What are the two divisions of the oculomotor nerves?
Superior division
Inferior division
What does the superior division of the oculomotor nerve innervate?
Superior rectus muscle
Levator palpebrae superioris muscle
What does the inferior division of the oculomotor nerve innervate?
Sphincter pupillae
Inferior rectus muscle
Medial rectus muscle
Inferior oblique muscle
What does the trochlear nerve innervate?
Superior oblique muscle
What does the abducens nerve innervate?
Lateral rectus muscle
What forms the optic nerve?
Axons of ganglion cells in ganglionic layers of retina
Pathway of optic nerve?
Leave orbital cavity through optic canal and unites with the contralateral optic nerve to form optic chiasma
Where is the optic chiasma located?
Junction of anterior wall and floor of 3rd ventricle
What structures pass through the optic chiasma?
Nasal half of each retina crosses in the optic chiasma, entering the optic tract of the opposite side. Temporal half passes posteriorly directly
Pathway of Optic tract?
Passes posterolaterally around cerebral peduncle, terminate by synapsing with LGB
What forms the optic radiation?
Fibers of the radiation are axons of nerve cells of LGB
Pathway of Optic radiation?
Passes posteriorly through retrolenticular part of the internal capsule and terminates at the visual cortex
What is Area 17?
Primary Visual Cortex
What areas form the visual association area?
Area 18
Area 19
What is the function of the visual association cortex?
Recognition of objects and perception
What structures does the retinal ganglion cells project into?
LGB
Hypothalamus
Prectum
Superior colliculus
What layers of the LGB does the nasal field project to?
Layer 2, 3, 5
What visual information contributes to depth perception?
Images are upside down
Information from one half of the visual field is directed to opposite side of brai
What is the importance of the LGN in visual processing?
Principal subcortical site for processing visual information
What layers of the LGN make up the magnocellular layers?
Layer 1
Layer 2
What layers of the LGN make up the parvocellular layers?
Layer 3 - 6
Where does the LGN project to?
Primary Visual cortex [Area 17]
What is Meyer’s loop?
Fibers representing inferior retina loop into temporal lobe before turning posteriorly
Where is the primary visual cortex located?
Around calcarine sulcus in occipital lobe
Describe the representation of visual fields in visual cortex
Inferior field → above calcarine sulcus
Superior field → below calcarine sulcus
Fovea → represented posteriorly and much larger than peripheral representation
Peripheral → more anteriorly and smaller than fovea representation
What is the afferent limb of pupillary light reflex?
Optic Nerve
What is the efferent limb of the pupillary light reflex?
Oculomotor nerve
Pathway of Pupillary Light Reflex?
AL: Retina → Optic nerve → bilateral projection to ipsilateral pretectal nucleus of the midbrain
EL: Ipsilateral Pretectal nucleus → crossed and uncrossed fibers to Edinger-Westphal Nucleus → preganglionic parasympathetic fibers to ciliary ganglion → postganglionic parasympathetic fibers → ciliary sphincter
Lesion of the left optic nerve will result in?
Loss of pupillary reflex in both eyes
Lesion of the left oculomotor nerve will result in?
Loss of pupillary reflex in left eye
What is the afferent limb of the corneal reflex?
Ophthalmic division of Trigeminal nerve
What is the efferent limb of the corneal reflex?
Facial nerve
Lesion of the ophthalmic division of trigeminal nerve will result in?
Bilateral absence of blinking response
Lesion of the Facial nerve will result in?
Absent blinking on affected side
Describe the visual body reflex
Optic nerve → superior colliculus → Tectospinal + Tectobulbar → anterior gray columns of motor nuclei of SC and CN
What produces complete blindness in one eye?
Optic nerve lesion
What produces bitemporal hemianopia?
Lesion in optic chiasma
Pituitary tumor
What produces nasal hemianopia?
Outer optic tract lesion
ICA thrombus
What produces Homonymous Hemianopia?
Optic tract lesion
What produces superior quadrantanopia?
Meyer’s loop lesion
Contralateral temporal lesion
What produces inferior quadrantanopia?
Dorsal optic radiation lesion
Contralateral parietal lesion
What produces right hemianopia with macular sparing?
PCA infarcts
What are the three layers of the eye?
Fibrous layer
Vascular layer
Inner Layer of eyeball
What forms the fibrous layer of the eye?
Sclera
Cornea
What forms the vascular layer of the eye?
Choroid
Ciliary body
Iris
What forms the neural layer of the eye?
Retina
What are the functions of the fibrous layer of the eye?
External fibrous skeleton that provides shape and resistance
What is the sclera? Its function?
Opaque part of fibrous coat, covering posterior ⅚ of eyeball
Provides attachment for extrinsic and intrinsic muscles of the eye
What is conjunctiva?
Membrane that covers the eye and lines the inner surface of the eyelid
What is the function of the conjunctiva?
Lubricates the eye by secreting mucous and tear
Protective barrier against microbes
Describe the structure of the cornea
Stratified corneal epithelium
Bowman’s membrane
Stroma
Endothelium
Describe the stroma of the cornea
Avascular
Rich in collagen fibers that are arranged to allow transmission of light
Fibroblasts (some)
What is the vascular supply of the cornea?
[Avascular structure]
Nourished by peripheral capillary bed and fluids on its external and internal surfaces
Lacrimal fluids also provide oxygen absorbed from air
What is choroid?
A highly pigmented dark brown membrane found between the sclera and retina that attaches firmly to pigmented layer of retina but is easily stripped of the sclera
[Forms largest part of the vascular layer]
Consists of smaller vessels adjacent to the retina and larger vessels more peripherally
Represents ⅔ of vascular layer
What supplies the choroid?
6 short peripheral ciliary arteries
2 long posterior arteries [passes through sclera and choroid]
What is uveitis?
Inflammation of vascular layer of eye
What innervates the ciliary muscle?
Supplied by parasympathetic fibers from the oculomotor nerves
What is the function of the ciliary body?
Changing convexity of lens to focus on near/distant object
What is the function of the ciliary process?
Secretes aqueous humor
What is the ciliary body?
Musculature and vasculature body that connects the choroid to the iris
What is the iris?
Contractile, pigmented diaphragm with a central aperture for transmitting light
Describe the ciliary muscles and other muscles with and in the absence of parasympathetic stimulation
haha
What is the function of the iris?
Control light input to retina, by contracting peripheral sphincters and radial dilators
What is coloboma?
Absence of a section of the iris, may be a result of a birth defect
What are the two muscles controlling the iris?
Dilator pupillae
Sphincter pupillae
What is mydriasis?
dilation of the eye
Innervation of the dilator pupillae muscle?
Innervated by the superior cervical, and under the control of the Sympathetic system
Innervation of the sphincter pupillae?
Innervated by the CN3, and under control of the parasympathetic system
What is miosis?
Abnormal constriction of the eye
What is the anterior chamber?
Space between the cornea anteriorly and the iris/pupil posteriorly
What is the posterior chamber?
Space between the iris/pupil anteriorly and the lens and ciliary body posteriorly
Describe the flow of aqueous humor through the chambers
Aqueous humor is secreted into the posterior chamber, where it then flows through the pupil and into the anterior chamber
Aqueous humor is absorbed in?
This absorbed in the scleral venous sinus
What is the canal of schlemm?
The scleral venous sinus, which is found at the junction between the cornea and the iris
What maintains the intraocular pressure?
Aqueous humor
What are the three gross layers of the retina?
Optic [neural and pigmented layers]
Ciliary
Iridial
What is the ora serrata?
Irregular body found slightly posterior to the ciliary body and marks the anterior termination of light-receptive part of the retina
List the layers of the retina
1- Retinal pigment epithelium
2- Rodes and Cones layer
3- Outer Nuclear layer
4- Outer Plexiform layer
5- Inner nuclear layer
6- Inner Plexiform layer
7- Ganglion cell layer
8- Nerve Fiber layer
What makes up the Nuclear layers?
Outer nuclear Layer- Cell bodies of photoreceptors
Inner Nuclear Layer- Cell bodies of Bipolar, amacrine and Horizontal cells
What makes up the Plexiform layers?
Inner Plexiform Layer- Axons of Bipolar and Amacrine cells
Outer Plexiform Layer- Axons of Photoreceptors and Horizontal cells
What is the function of photoreceptors?
Neurons capable of phototransduction
What is the function of horizontal cells?
Integrate and regulate input from multiple photoreceptors to bipolar cells
What is the function of bipolar cells?
Transmits signals from photoreceptors and horizontal cells to retinal ganglion cells
What is the function of amacrine cells
Regulate input from multiple bipolar cells
What is the function of Retinal ganglion cells?
Transmit visual information from retina to multiple regions of the cortex
What is the retinal pigment epithelium?
Single cuboidal melanin rich layer found between choroid and the outer tip of photoreceptors
What is the function of the retinal epithelium layer?
Light absorption
Epithel transport
Glia
Visual Cycle
Phagocytosis
Secretion
What structures make up the blood-retinal barrier?
Retinal pigment epithelium
Bruch’s membrane
What is retinal detachment?
Detachment of the Retinal pigment epithelium from the neuronal layer
What is the optic disc?
Where the optic nerve enters the eyeball, thus contains nerve fibers and no photoreceptors, forming a blindspot
What are the characteristics of rods and cones?
What parts make up the fundus of the eye?
Macula
Fovea
Optic disc
Retina
What is the macula?
Small depression just about the center of the eye
What is the fovea?
Rod-free region at the center of the macula
What is the functional relevance of the fovea?
Center of the eye’s sharpest vision and location of most color perception [cones]
Blood supply of Eye:
Internal carotid artery → ophthalmic artery → :
1- Central retinal artery
2- Short and Long Posterior ciliary arteries
3- Anterior Ciliary Arteries
What vessel innervates the retina?
Central artery → supplies the retina, except the cones and rods
Choriocapillaris → supplies the cones and rods of the neural layer
Describe the course of the central artery and the optic nerve
Central artery runs within the dural sheath of the optic nerve, then it pierces the nerve and runs within it to emerge at the optic disc
Obstruction of Blood supply of the retina
Their terminal branches provide the only blood supply to the retina, if they are obstructed by an emboli, then it leads to total blindness
Pathophysiology of Papilledema
↑CSF pressure → slows venous return from retina → retinal edema → papilledema
What are the refractive medias in the eye?
Cornea
Aqueous humor
Lens
Vitreous humor
What is the primary refractive media of the eye?
cornea
What is the lens?
Transparent biconvex elastic disc enclosed by a capsule and anchored to the ciliary body by the zonular fibers
Describe lens accommodation
Parasympathetic stimulation of the ciliary muscle through CN 3 causes the tension on the lens to reduce, thus allowing the lens to round up
Define myopia
Near-sightedness, refractive error
Define hyperopia
Far-sightedness
What is vitreous humor?
Clear gel that occupies area behind the lens and before the retina at the back of the eye
What makes up the vitreous humor?
Mostly water, lower amounts of collagen, salt and sugar
What is the function of the limbic system?
Involved in control of emotions, behavior and memory
What structures form the limbic system?
- Subcallosal
- Cingulate
- Parahippocampal gyri
- Hippocampal formation
- Amygdaloid nucleus
- Mammillary bodies
- Anterior Thalamic nucleus
What structures form the hippocampal formation?
- Hippocampus proper
- Dentate gyrus
- Parahippocampal gyrus
What is the deepest layer of the hippocampal formation?
Dentate gyrus
What is the subiculum?
transitional area between hippocampus proper and the entorhinal cortex of the parahippocampal gyrus
What is the entorhinal cortex?
Part of the medial temporal lobe and constitutes the major gateway between the hippocampal formation and the neocortex
When does the Hippocampal formation begin ?
12-32 weeks post-conception
At which week does the hippocampus sulcus appears in the fetus
Week 10-11
Describe the formation of the fornix
Alveus → Fimbria → Crus of fornix
What part of the hippocampus formation plays a role in neurogenesis?
Dentate Gyrus
What structure does the entorhinal cortex communicate with?
Dentate Gyrus
What are the principal cells of the Hippocampus?
Large pyramidal neurons found in the pyramidal layer
Where is the molecular layer of the hippocampus found?
In the dentate gyrus
What are the three layers of the hippocampus?
The outer layer is the molecular layer, the middle layer is the pyramidal layer, and the inner layer the stratum oriens
Describe the structure of the hippocampal subfield [CA1, CA2, CA3, CA4]
The move along the c-shaped structure, starting at the beginning of the hippocampus and ends embedded into the dentate gyrus. CA1 → CA2 → CA3 → CA4
Describe the structure of the Molecular layer
In the centre of the hippocampal formation, the layer consists of interacting axons and dendrites
Describe the structure of the Pyramidal Layer
Composed of large pyramid neurons with their dendrites extending into the molecular layer and axons transverse alveus + fimbria to reach fornix
What are the three principle pathways for information processing in the hippocampus?
- Perforant pathway
- Mossy Fiber Pathway
- Schaffer Collateral pathway
Which processing pathway is the first to degenerate in AD?
Perforant pathway
Describe the Perforant pathway
From entorhinal cortex to granule cells of dentate gyrus
Describe the Mossy Fiber pathway
From granule cells of dentate gyrus to CA3 region of hippocampus
Describe the Schaffer Collateral pathway
From CA3 to CA1 region of the hippocampus
Which principal pathway is important for memory consolidation?
Schaffer Collateral pathway [memory consolidation + Long term potentiation]
What is the importance of the Schaffer Collateral pathway?
[memory consolidation + Long term potentiation]
Where does the entorhinal cortex receive input from?
- Neocortex
- Cingulate cortex
- Temporal lobe cortex
- Orbital cortex
- Olfactory bulb
Where does the fornix receive input from?
Septal area
Hypothalamus
What is the septal area?
Collection of nuclei in association to septum pellucidum. These nuclei play a role in regulating limbic system
List all the hippocampus efferents
- Subiculum
- Fornix
- Precommissural Fornix
- Postcommissural Fornix
- Anterior Commissure
Where does the fornix send information to?
- Alveus
- Fimbria
- Crura
- Hippocampal commissure
- Contralateral hippocampus
What structures does the postcommissural fornix send information to?
Mammillary bodies, then indirectly through the anterior thalamic nuclei through the mammillothalamic tract.
Describe the connection between the cingulate gyrus and the hippocampus
There’s no direct connection between the two structures instead:
Postcommissural fornix → mammillary bodies → anterior thalamic nuclei → Cingulate Gyrus → Entorhinal cortex + Hippocampus
What syndrome affects the mammillary bodies of the hypothalamus?
Korsakoff’s Syndrome
What is the major efferent structure of the Hippocampus?
Fornix
What structure connects the two hippocampi?
Anterior Commissure
What structures does the precommissural fornix of the hippocampus send information to?
- Septal nuclei
- Ventral striatum
- Orbital cortex
- Anterior cingulate cortex
List the Hippocampal Afferent
- Amygdala
- Contralateral Hippocampus
- Fornix
- Entorhinal Cortex
What structure connects the Anterior Thalamic nucleus to the Cingulate Gyrus?
Anterior Limb of the Internal Capsule
What structure connects the Cingulate Gyrus to the Parahippocampal Gyrus?
Cingulum
What structure connects the hippocampal formation, preoptic hypothalamus and the septal area together?
Precommissural fornix
What structure connects the Hippocampal Formation, Mammillary body and Anterior Thalamic Nucleus?
Postcommissural fornix
What structure connects the Mammillary body to the Anterior Thalamic Nucleus?
Mammillothalamic Tract
What structure is affected in AD?
Circuit of Papez
Describe the Circuit of Papez
What are the boundaries of the hypothalamus?
- Superior:
- Hypothalamic sulcus
- Posterior [+inferior]
- Mammillary bodies
- Inferior:
- Infundibulum
- Anterior:
- Anterior Commissure
- Lamina terminalis
- Optic chiasm
What are the zones of the hypothalamus?
- Periventricular zone
- Medial zone
- Lateral zone
What is the function of the lateral zone of the hypothalamus?
Regulation of CVS
What is the function of the medial zone of the hypothalamus?
Regulating ANS [specifically GIT] and neuroendocrine system
What is the function of the Periventricular zone?
Regulating neuroendocrine functions
What nuclei compromise the periventricular zone of the hypothalamus?
- Arcuate nucleus
- Paraventricular nucleus
What nuclei compromise the medial zone of the hypothalamus?
- Paraventricular
- Preoptic
- Anterior
- Suprachiasmatic
- Supraoptic
- Dorsomedial
- Ventromedial
- Arcuate Nucleus
- Posterior
- Mammillary
Describe the hippocampus in Alzheimer’s patients
Significant atrophy of the hippocampus
What are the 3 principal pathways for information processing in the Hippocampus?
- Perforant Pathway
- Entorhinal cortex → Dentate gyrus [granular cells]
- Mossy Fiber Pathway
- Dentate Gyrus → CA3
- Schaffer Collateral Pathway
- CA1 → CA3
What nuclei compromise the lateral zone of the hypothalamus?
- Median forebrain bundle [?]
- Lateral Complex nucleus
- Supraoptic nucleus
- Preoptic nucleus
Describe the location and anatomy of the amygdala
Sits below uncus
Almond-shaped structure continuous with the hippocampus
Which structure(s) does the amygdala receive afferent visceral input from?
- Hypothalamus
- Septal area
- Orbital Cortex
- Hippocampus
Which structure(s) does the amygdala receive afferent olfactory input from?
Olfactory bulb
Which structure(s) does the amygdala receive afferent auditory, visual and somatosensory input from?
Temporal cortex
Anterior cingulate cortex
What are the 5 efferent pathways from the amygdala?
- Ventral amygdalofugal pathway
- Stria terminalis
- Directly to hippocampus
- Directly to entorhinal cortex
- Directly to dorsomedial nucleus of thalamus
Describe the Ventral Amygdalofugal pathway
Sends information back to where it received the inputs
- Hypothalamus
- Septal area
- Orbital cortex
- Olfactory bulb
- Ventral striatum [GP to the basal ganglia]
What is the role of stria terminalis?
Major efferent connection from the amygdala to the hypothalamus and septal nucleus
What is the function of the amygdala?
Integration center for emotions, emotional behaviour, and motivation
Involved in fear conditioning
What structure is involved in fear conditioning?
Amygdala
Describe the amygdala in patients with Bipolar disorder
Reduced volume and activity of amygdala
Describe the amygdala in patients with anxiety disorder
Higher activity
What is the effect of a lesion in the amygdala?
Lose fear ability and fear recognition
What structure connects the Hypothalamus and Amygdala?
- Stria terminalis
- Ventral Amygdalofugal tract
- Direct projections
What structures connect the Hypothalamus and Hippocampus?
Fornix
What two structures connect the Hypothalamus and Pituitary gland?
- Tubero-hypophyseal tract
- Supraopticohypophyseal tract
What structure connects the Hypothalamus to the Brainstem?
Medial Forebrain Bundle
What structure connects the Brainstem to the Hypothalamus?
Dorsal Longitudinal Fissure
What structure in the hypothalamus receives information from the retina?
Supraoptic nucleus
What structure indirectly connects the septal nucleus to the brainstem via the hypothalamus?
Medial Forebrain bundle
What structures are found in the Tuberohypophyseal tract and what do they release?
- Paraventricular and Arcuate Nuclei, they release:
- CRH
- TRH
- GHRH
- Dopamine
What structures are found in the Supraopticohypophyseal tract, and what do they release?
- Paraventricular and Supraoptic nuclei, and they release
- ADH [vasopressin]
- Oxytocin
Which hypothalamic nuclei are found in the tuberal region?
- Paraventricular
- Dorsomedial
- Ventromedial
- Arcuate
- Lateral Complex
Which hypothalamic nuclei are found in the anterior region?
- Paraventricular
- Preoptic
- Anterior
- Suprachiasmatic
- Supraoptic
Which hypothalamic nuclei are found in the posterior region?
Posterior
Mammillary
Which hypothalamic nuclei play a role in thermoregulation?
Posterior
Anterior
Preoptic
What are the similarities and differences between the Lateral Complex and Ventromedial nuclei?
Sim: Appetite + Body weight control
Dif: insulin [ventromedial]
Which hypothalamic nucleus is responsible for biological rhythms?
Suprachiasmatic nucleus
What are the functions of Preoptic and Anterior Thalamic Nuclei?
Lateral Anterior Thermoregulation and Sexual Behavior
What is the function of the dorsomedial nucleus?
Responsible for Emotions [Rage]
What structure regulates the dorsomedial nucleus?
Amygdala
What is the function of the Mammillary nucleus and How does it achieve it?
Responsible for emotion and Short term memory through its connection with the hippocampus
What are the similarities and differences between Paraventricular and Supraoptic nuclei?
Sim: Fluid balance, mild let-down and partition
Dif: Autonomic and Anterior Pituitary control [Paraventricular nucleus]
What is the function of the Arcuate nucleus?
Feeding
Control of Anterior Pituitary
What is the function of the thalamus?
- Relay station of Somatostatic and visceral sensations through hypothalamus
- Poorly perceives crude sensations [pain + temperature]
- Cortex is still required for interpretation based on past experience
- Maintenance of states of wakefulness and alertness through RAS
- Regulates activities of motor pathways [VA & VL nuclei]
- Regulates Emotional activity and memory function [dorsomedial nuclei]
Where would the thalamus be found?
Lateral wall of the 3rd ventricle
What structures are found on the upper surface of the thalamus?
Choroid fissure
Stria terminalis
Thalamostriate vein
What forms the floor of the central part of the lateral ventricle?
Upper surface of the thalamus
What does the upper surface of the thalamus form?
Central part of the lateral ventricle
What does the medial surface of the thalamus form?
Lateral wall of the 3rd ventricle
What surface of the thalamus interacts with its surrounding structures?
Lower Surface
What structures are related to the lower surface of the thalamus?
- Fasciculus subthalamicus
- Dentato-rubro-thalamic fibers
- Fasciculus lenticularis
- Ansa lenticularis
- Subthalamic nuclei
- BG via the globus pallidus
What is the external medullary lamina?
Thin white matter covering the lateral surface of the thalamus
What separates the thalamus and the lentiform nucleus?
Posterior limb of the internal capsule
What connects the hippocampus to the thalamus?
Indirectly through the mamillary bodies
- Hippocampus → fornix → mammillary bodies → Mammilothalamic tract → Anterior thalamic nucleus → cingulate gyrus → cingulum → Hippocampus
What structure is affected in Korsakoff’s syndrome?
Anterior Thalamic Nucleus
What syndrome is associated with alcoholics?
Korsakoff’s syndrome
What is the effect of a lesion to VPL and VPM?
Loss of complete sensation on the contralateral side of the body
Why are the symptoms of thalamic lesions often overshadowed?
Lesions often result in dysfunction of neighbouring structures producing signs and symptoms that overshadow those that are produced by the thalamic lesion itself
What is the effect of a lesion on the Intralaminar nucleus?
Thalamic neglect [unilateral]
What is the effect of a lesion on the Anterior nucleus?
Korsakoff’s Syndrome
What is the effect of a lesion on the Dorsomedial nucleus?
Spontaneous crying or laughing
What is the effect of a lesion on the Ventral Anterior and Ventral Lateral nuclei?
Why do lesions on VA and VL nuclei produce choreo-athetosis?
Through the connections from corpus striatum and cerebellum
What is the effect of a lesion on the Ventral Posterior nucleus?
Diminished sensation on contralateral side
What is thalamic neglect?
Unilateral neglect of stimuli originating from the contralateral body
What is the function of the reticular thalamic nucleus?
Inhibitory modulation of thalamocortical transmission
What is the function of the Intra-laminar nucleus?
Influences the level of consciousness and alertness
What structures do the intra-laminar group of nuclei send eference to?
Caudate nucleus
Putamen
Cerebral cortex [via thalamic nuclei]
What structures do the intra-laminar group of nuclei receive aference from?
Ascending reticular fibers from Brainstem RF
Spinothalamic tracts
Trigeminothalamic tracts
What structures do the midline group of nuclei receive aference from?
Reticular Formation
NA, Cholinergic and serotonergic fibers
What structures do the midline group of nuclei send eference to?
Hippocampal formation
Amygdala
Nucleus accumbens
What structures does the reticular thalamic nuclei receive aference from?
Cerebral cortex
Brainstem reticular nuclei
What structures does the reticular thalamic nuclei send eference to?
To other thalamic nuclei that sends afferents to reticular nucleus
What is the function of the Ventral Posterior nucleus?
Processing and integrating sensory information
What is the function of the Ventral Lateral and Ventral Anterior nuclei?
Sends motor information from the cerebellum and BG to the cortex
- Regulates voluntary movement and muscle tone
What is the function of the Dorsomedial nucleus?
Integration of sensory information / Emotional feelings
What is the function of the Anterior Nucleus?
Recent memory and emotion
What is the role of the thalamus in voluntary movement?
Regulates voluntary movement and influences the muscle tones via the direct and indirect pathways of the cerebellum
What arteries supply the thalamus?
- Thalamogeniculate artery [branch of PCA]
- Anterior Choroidal artery [Branch of ICA]
- Posterior communicating artery contributing to both
What structures does the anterior thalamic nuclei receive aference from?
What structures does the anterior thalamic nuclei send eference to?
Cingulate Gyrus
What structures does the Dorsomedial nuclei receive aference from?
Orbitofrontal cortex
Amygdala
Hypothalamus
+ Other thalamic nuclei
What structures does the Ventral anterior nuclei receive aference from?
Globus Pallidus
Substantia Nigra
What structures does the Ventral Lateral nuclei receive aference from?
Dentate nucleus of Cerebellum
Red nucleus
Globus Pallidus
What structures does the Ventral Posterolateral [VPL] nuclei receive aference from?
Medial Lemniscus
Spinal Lemniscus
What structures does the Ventral Posteromedial [VPM] nuclei receive aference from?
Trigeminal lemniscus
Solitario-thalamic tract
What structures does the Medial Geniculate body nuclei receive aference from?
Inferior Colliculus
What structures does the Lateral Geniculate body nuclei receive aference from?
Optic tract
What structures does the intralaminar nuclei receive aference from?
Reticular formation of brainstem
Pain fibers
What structures does the dorsomedial nuclei send eference to?
Prefrontal cortex
What structures send efference to the Premotor cortex?
Ventral Anterior & Ventral Lateral
What structures send efference to the Postcentral gyrus [Area 3,1,&2]?
Ventral Posterolateral nucleus
Ventral Posteromedial nucleus
What structures does the LGB nuclei send eference to?
Lips and Walls of Calcarine Sulcus [Area 17]
What structures does the MGB nuclei send eference to?
Anterior and Posterior Transverse Temporal gyrus [41, 42]
Describe the clinical presentation of Dejerine-Roussy disease
- Absence of sensation and tingling of body contralateral to lesion [initial] → numbness [months] → severe chronic pain
- Thalamic Phantom limb
- Decrease in tension, aggression and anxiety
- Increased forgetfulness
- Emotional instability w/spontaneous crying/laughing
- Intention tremor
- Choreoathetosis
What structure affected in Dejerine-Roussy disease causes decreased tension, anxiety and aggression?
Medial nucleus
What structure is cauterized surgically for pain relief?
Intralaminar nuclei
What structure affected in Dejerine-Roussy disease causes choreoathetosis or intention tremor?
Ventral Anterior nucleus
Ventral Lateral nucleus
List all Thalamic nuclei
- Anterior nucleus
- Pulvinar nucleus
- Medial Geniculate body
- Lateral Geniculate body
- Dorsomedial nucleus
- Intralaminar nuclei
- Midline nucleus
- Dorsolateral nucleus
- Posterior Lateral nucleus
- Ventral Anterior nucleus
- Ventral Intermediate nucleus
- Ventral Posterolateral nucleus
- Ventral Posteromedial nucleus
What does damage to the medial thalamic nucleus produce?
Decrease in tension, aggression, anxiety
Increases forgetfulness
Emotional instability with spontaneous crying or laughing
What does damage to VA and VL nuclei produce?
Intention tremor
Describe the clinical presentation of thalamic infarct
Initially, contralateral hemianesthesia
Months later, numbness → severe chronic pain
Pathophysiology of Severe chronic pain in cases of thalamic nuclei
Absence of central cortical inhibition causing excruciating pain [involvement of thalamogeniculate branch]
Surgery pain relief involves which thalamic nuclei?
What is another name for Thalamic pain syndrome?
Dejerine - Roussy disease
What is the function of the dorsomedial nucleus?
Integration of somatosensory information and relates it to emotional feelings and subjective states
What is the input and output of the VPL?
Input: Medial and Spinal Lemniscus
Output: Area 3, 1, 2
What is the input and output of the Anterior and Lateral Dorsal Thalamic Nuclei?
Input: Mamilary body
Output: Cingulate gyrus
What is the input and output of the Dorsomedial Thalamic nuclei?
Prefrontal
Orbitofrontal cortex
Amygdala
Hypothalamus
What is the input and output of the Lateral Posterior Thalamic nucleus?
Input: Ventral Lateral nucleus, Pulvinar Nucleus
Output: Superior Parietal lobule [Area 5 & 7]
What is the input and output of the VPM?
What is the input and output of the Ventral Lateral Thalamic Nucleus?
What is the input and output of the Ventral Anterior Thalamic Nucleus?
Input: Brainstem Reticular nuclei, Substantia nigra, globus pallidus
Output: Area 6
What structures are implicated in homonymous hemianopia?
Lateral Genicular
Optic radiations
Visual cortex
What structures are implicated in dysesthesia?
Irritation of thalamus
What structures are implicated in loss of proprioception?
VPL
Posterior limb of internal capsule
Medial Lemniscus
What structures are implicated in spastic hemiplegia in lesion of posterior thalamus?
Posterior limb of internal capsule
What structures are implicated in Involuntary choreoathetoid and blank face?
GP
Subthalamic nuclei
VL thalamic nucleus
What are the signs of lesion of posterior thalamus?
Dysesthesia
Spastic hemiplegia
Loss of proprioception
Involuntary choreoathetoid movements
Face ‘blank mask’
Homonymous hemianopia
What structures make up the Striatum or Neostriatum?
Caudate + Putamen
What structure is found medial to the Straitum?
Globus Pallidus [Ext. → Int.]
What structures make up the lenticular nucleus?
Putamen + Globus Pallidus
What structure forms the major output of the BG?
Globus pallidus
What structure forms the major input into the BG?
Striatum [Caudate + Putamen]
What structure is found superior to the substantia nigra?
Subthalamic nucleus
Which structure is affected in Parkinson’s?
Substantia Nigra
What structures make up the Basal Ganglia?
- Substantia Nigra
- Subthalamic nucleus
- Caudate
- Putamen
- Globus Pallidus
- Amygdala
What are the major afferent projections of the Basal Ganglia?
- Corticostriatal fibers
- Thalamostriate fibers
- Nigrostriatal fibers
- Brainstem Striatal fibers
Describe the connection between SC and Basal Ganglia?
No direct input or output between the two
Describe the corticostriatal fibers
Cerebral cortex → Caudate + Putamen
[Neurotransmitter: Glutamate]
Describe the Thalamostriate fibers
Intralaminar nuclei of thalamus → Caudate + Putamen
Describe the Nigrostriatal Fibers
Dopaminergic neurons from substantia nigra → Caudate + Putamen
Describe the Brainstem Striatal Fibers
Ascending fibers from brainstem → Caudate + Putamen
[Serotonin release at their terminals]
What are the major efferent projections of the Basal Ganglia?
- Striatopallidal fibers
- Striatonigral fibers
- Pallidothalamic fibers
- Pallido Tegmental fibers
Describe the striatopallidal fibers
Caudate + Putamen → Globus Pallidus
[Neurotransmitter: GABA]
Describe the Striatonigral fibers
Caudate + Putamen → Substantia nigra
[Neurotransmitters: GABA + Ach]
Describe the Pallidothalamic fibers
Ansa lenticularis + Lenticularis fasciculus to form thalamic fasciculus
What is the claustram?
Thin sheet of gray matter separated from the lateral surface of lentiform nucleus by the external capsule
What blood vessel supplies the putamen?
Penetrating branches of ACA / Recurrent Artery of Heubner
What blood vessel supplies the caudate nucleus?
Lenticulostriate arteries [branch of MCA]
What blood vessel supplies the globus pallidus?
Anterior Choroidal artery
What blood vessel supplies the thalamus?
Branches of the Posterior Choroidal artery:
- Thalamogeniculate arteries
- Thalamoperforator arteries
Describe the Direct Pathway
Cortex→ striatum excited → GPi inhibited → Thalamus no longer inhibited → motor cortex excited
Describe the Indirect Pathway
Cortex → Striatum excited → GPe inhibited → Subthalamic neurons are no longer inhibited → GPi excited → Thalamus inhibited → no signal sent to cortex
Describe the relationship between the Thalamus, Subthalamus neurons and GPi
GPi inhibits the thalamus when its active
Subthalamic neurons increase firing rate of GPi when its activated
What are cholinergic interneurons?
Neurons within the striatum, and synapse in GABAergic striatal neurons that project to GPi and GPe
What role do cholinergic interneurons play in information processing?
Inhibits striatal cells of direct pathway and excite cells of the indirect pathway
Describe the role of the nigrostriatal projection
Excites direct pathway [D1 receptor] and inhibits indirect pathway [D2 receptor]
What anatomical changes are seen in HD?
Selective loss of striatal neurons in the indirect pathway, tipping the favor to the direct pathway, thus thalamic neurons fire randomly and inappropriately
What anatomical changes are seen in PD?
Loss of dopaminergic neurons in substantia nigra pars compacta [nigrostriatal input], typing the favor to the indirect pathway
What are dural fold?
Double fold of meningeal layer of dura mater than contain dural venous sinuses, which receive superficial veins from the brain
What is the function of dural folds?
Provides support for brain
Incompletely divided cranial cavity into compartments
What structures are found in the Superior Sagittal Sinus?
Emissary veins
CSF from subarachnoid space
Where is the Superior Sagittal Sinus located?
Where is the Falx Cerebri located?
Where is the Inferior Sagittal Sinus located?
At free margin of falx cerebri
What vessels are found in the Falx cerebri and Inferior Sagittal Sinus?
What are the attachments of the Falx cerebri?
Cresta Gali
Sagittal Sulcus
Superior Surface of Tentorium cerebelli
What are the attachments of the Falx Cerebelli?
Internal occipital crest
What are the attachments of the Tentorium Cerebelli?
Superior border of petrous part of temporal bone
Transverse sulcus
Anterior Clinoid process [free margin]
What are the attachments of the Diaphragma sellae?
Margins of Pituitary fossa
What structures form the internal jugular vein?
Sigmoid sinus + Inferior Petrosal sinus → Superior bulb of intrajugular vein → Internal Jugular vein
What is the Ophthalmic vein? And what is its clinical significance?
Allows communication between the facial vein and cavernous sinus
Clinical significance facial infection can spread to cavernous sinus
Which part of the Internal Carotid artery is susceptible to aneurysm?
Cavernous part of ICA
What vessels does the Cavernous sinus communicate with?
What is the landmark for the Middle Meningeal Artery?
What arteries supply the meninges?
- Anterior and Posterior Ethmoidal arteries [of ICA]
- Middle Meningeal artery [Maxillary artery]
- Branches of occipital, Ascending pharyngeal and Vertebral arteries
Describe the extension of the 4th ventricle into the surrounding structures
Extends into cerebellum as superior recess.
Opens into subarachnoid space(Cisterna magna) at median aperture in the roof and at the two lateral apertures at lateral ends of the lateral recess.
What are the 4 parts of the lateral ventricles?
Anterior Horn
Body
Posterior Horn
Inferior Horn
Describe the body of Lateral Ventricle
Forms the level of interventricular foramen to the level of splenium of corpus callosum
What structure must be removed to visualize the lateral ventricle?
Septum Pellucidum
What forms the boundaries of the anterior horn of the lateral ventricle?
Where is the lateral ventricle found?
Anterior to level of interventricular foramen
What forms the floor of the Inferior horn of the lateral ventricle?
Hippocampus [medial] + Collateral Eminence [Lateral]
How does the choroid plexus enter the lateral ventricle?
Through the choroid fissure
What forms the boundaries of the body of the lateral ventricle?
Roof: Corpus Callosum
Floor: Thalamus [medial] + Body of Caudate nucleus [lateral]
Medial: Septum pellucidum + Body of Fornix
Describe the location of the choroid fissure
Superior part found between the body of fornix + thalamus
Inferior part found between fimbria of fornix + tail of caudate nucleus
What structure forms the calcar avis?
Calcarine sulcus
What forms the bulb of the posterior horn of the lateral horn?
Where is the collateral eminence found?
What forms the general boundaries of the 3rd ventricle?
What forms the boundaries of the lateral wall of the 3rd ventricle?
Lateral wall: Thalamus + Hypothalamus
Floor: Optic chiasm + Optic recess + Infundibulum + Infundibular recess + Mammillary body + tegmentum of midbrain
Posterior: Pineal gland + Pineal recess
Anterior: Lamina terminalis + Anterior Commissure
What forms the boundaries of the 4th ventricle?
Roof:
- Upper part: Superior Cerebellar Peduncle + Superior Medullary Velum
- Lower part: Medullary Velum + Tela chorodia
- Floor: Posterior surface of Pons + Open part of medulla oblongata
Lateral:
- Superolateral: Superior Cerebellar Peduncle
- Inferolateral: Inferior Cerebellar Peduncle
How does the choroid plexus project into the 4th ventricle?
Tela chorodia
What nerves innervate the dura mater
C2-C3 Spinal nerves
Recurrent meningeal branch of ophthalmic nerve
Meningeal branches of maxillary and mandibular nerves
Anterior and Posterior Ethmoidal nerves
What is the general mechanism of headaches?
What are meningeal headaches indicative of?
Meningitis
Cerebral tumor
Where is CSF produced?
What is the choroid plexus?
Soft tuft of fenestrated capillaries covered by pia mater and ependyma
Describe the ependyma of choroid plexus?
Cuboidal cells with microvilli
What is the normal volume and secretion of CSF
Normal ~150ml
Active Secretion ~ 0.5ml/min
What is controlled in CSF circulation, Regulation or Absorption?
Absorption
What maintains CSF pressure?
Absorption mechanism [60-150mm of water]
Where is CSF absorbed?
Perineural lymph vessels
Describe CSF circulation
Lateral Ventricle → interventricular foramen → 3rd ventricle → cerebral aqueduct → 4th ventricle → Median + Lateral aperture of 4th ventricle → Subarachnoid space → arachnoid villi + granulation → Dural venous sinus / Superior Sagittal sinus
What is the anatomical basis of ICP?
- Subarachnoid Hemorrhage
- Defective CSF absorption
- CSF flow pathway blockage
- Excessive CSF formation [pathological]
Describe the mechanism of Papilledema
Through the subarachnoid space around the optic nerve and reaches upto the posterior pole of the eyeball
What are the three lobes of the cerebellum?
Anterior lobe
Posterior lobe
Flocculonodular lobe
What structure splits the cerebellum into the anterior and posterior lobes?
What structure splits the cerebellum into the posterior and flocculonodular lobes?
What structures act as gateways to axons entering the cerebellum?
What are tonsils?
What structures do the axons leave the cerebellum through?
Superior Cerebellar Peduncle [SCP]
Inferior Cerebellar Peduncle [ICP]
What type of neurons are the intracerebellar nuclei?
What are the four deep cerebellar nuclei?
Dentate nucleus
Emboliform nucleus
Globose nucleus
Fastigial nucleus
Where is the dentate nucleus found?
Where is the fastigial nucleus found?
Where is the interposed nucleus found?
What structures form the interposed nucleus?
What are the vermis and flocculonodular lobes responsible for?
Control of proximal and trunk muscles
Vestibulo-ocular control
What is the intermediate zone responsible for?
Control of distal muscles in arms and legs
What is the lateral hemisphere responsible for?
Planning motor program for extremities
How does the vermis act?
Via the fastigial nuclei
How do the flocculonodular lobes act?
How does the intermediate zone act?
How does the lateral hemisphere act?
What is the function of the lateral cerebellar hemispheres?
What is the function of the Intermediate cerebellar hemispheres?
Distal limb coordination
What is the function of the vermis and flocculonodular lobes?
What regions of the cerebellum influence the lateral corticospinal tracts?
What motor pathways are influenced by the intermediate hemispheres?
What motor pathways are influenced by the vermis and flocculonodular lobe?
- Anterior corticospinal tract
- Reticulospinal tract
- Vestibulospinal tract
- Tectospinal tract
- Medial Longitudinal Fasciculus
What structures do the efferent fibers from the cerebellum connect with?
Describe the Corticopontocerebellar pathway
Describe the Cerebro-olivocerebellar pathway
Describe the anatomy of the Globose-Emboliform-Rubral Pathway
Describe the anatomy of the Dentothalamic pathway
Describe the Fastigial Vestibular Pathway
What is the function of the Fastigial Vestibular Pathways?
Describe the Fastigial Reticular Pathways
What is the function of the Fastigial Reticular Pathways?
What cerebellar pathways convey control from the cerebral cortex?
What cerebellar pathways convey information from muscle and joints?
What is the function of the Cuneocerebellar pathway?
What is the function of the Vestibular nerve?
What structures are supplied by SCA?
Anterior lobe
Deep Cerebellar nuclei
Superior Cerebellar Peduncle
What structures are supplied by AICA?
Ventral part of the posterior lobe
Middle Cerebellar Peduncle
What structures are supplied by PICA?
What are the three layers of the cerebellar cortex?
Pathway of Climbing fibers
Pathway of Mossy Fibers
Lesion in what part of the cerebellum would produce truncal ataxia? What other symptoms does it produce?
Lesion in what part of the cerebellum would produce Appendicular ataxia?
Where are cerebellar infarcts more common?
Describe the clinical presentation of Cerebellar infarcts
What are some risk factors for Cerebellar Hemorrhage?
Describe the clinical presentation of Cerebellar Hemorrhage
What is the clinical significance of the vestibular system in lesions of cerebellum?
Due to strong connections between the two structures
Lesions associated with
- Vertigo
- Nystagmus
- Vomiting
What pathways send somatosensory information to the cerebellum?
Pathway of Anterior Spinocerebellar tract
DRG → Clarke’s column → Superior Spinocerebellar Peduncle, as mossy fibers and can give collateral branches
Ipsilateral and contralateral
Pathway of Posterior Spinocerebellar tract
DRG → Clarke’s column → ipsilateral white column → ipsilateral inferior cerebellar peduncle as mossy fibers and gives collateral branches
Pathway of Cuneocerebellar Tract
What information does the Anterior Spinocerebellar tract carry?
Somatosensory information from the Upper and Lower Limbs
What information does the Posterior Spinocerebellar tract carry?
Somatosensory information from the Trunk and Lower limbs
What information does the Cuneocerebellar tract carry?
Somatosensory information from the Upper Limb and Upper part of the thorax
What afferent pathway pass through the Superior Cerebellar Peduncle?
Anterior Spinocerebellar Tract
What afferent pathways pass through the Inferior Cerebellar Peduncle?
Posterior Spinocerebellar Tract
Cuneocerebellar Tract
Vestibular input
Where do afferents from the inner ear terminate?
Flocculonodular lobe
Vestibular input to Cerebellum
Vestibular nerve → ipsilateral inferior cerebellar peduncle
Vestibular nerve → vestibular nuclei → ipsilateral inferior cerebellar peduncle
What structures connect with efferent fibers from the cerebellum?
Red nucleus
Vestibular nucleus
Reticular formation
Thalamus
What forms the output of the cerebellar cortex?
Through axons of purkinje cells, which
- Synapse with deep cerebellar nuclei
- Leave directly to lateral vestibular nucleus
What are the interneurons in the cerebellum?
Stellate and Basket cells
What is the function of interneurons?
Basket and Stellate cells inhibits purkinje cells through the parallel fibers
Where are interneurons found?
In the molecular layer
Describe the relationship between Climbing fibers and deep cerebellar nuclei
Climbing fibers can excite DCN directly or can indirectly inhibit it via the purkinje cells [exciting purkinje cells would inhibit DCN]
Describe the relationship between Purkinje fibers and DCN
Has an inhibitory effect on DCN
Pathway of Mossy Fibers
Mossy fibers → Granule cells → Parallel fibers → :
- Golgi cells → inhibit granule cells → reduce excitatory effects on Purkinje cells
- Basket cells → inhibits purkinje cells
What vessels supply the pons and spinal cord?
Describe the course of the vertebral arteries
Arises from the subclavian arteries and ascends the posterior aspect of neck through the foramen transversarium
What vessel arises medially to the anterior scalene muscle?
What are the branches of the Internal Carotid Arteries?
- Ophthalmic artery
- Posterior Communicating artery
- Anterior Choroidal artery
- Anterior Cerebral artery
- Middle Cerebral artery [continuation of ICA]
Which branch of the ICA is important for motor control and vision?
Anterior Choroidal artery
What are the three paired vessels that make up the Circle of Willis?
- Anterior Cerebral artery
- Posterior Cerebral artery
- Internal Carotid artery
What are the branches of the Vertebral arteries?
- Meningeal branch
- Anterior Spinal Arteries
- Posterior Spinal Arteries
- Posterior Inferior Cerebellar artery
- Basilar artery
What vessel is implicated in Locked-In Syndrome?
What vessel is implicated in Medial Medullary Syndrome?
What vessel is implicated in Lateral Pontine Syndrome?
AICA- Anterior Inferior Cerebellar Artery
What vessel is implicated in Lateral Medullary [Wallenberg] Syndrome?
How do the basilar arteries terminate?
Where does the ICA originate
What arteries supply the anteromedial portion of the cerebrum?
What arteries supply the lateral portion of the cerebrum?
What arteries supply the posterior portion of the cerebrum?
What does the Anterior Cerebral artery supply?
Why are ACA infarcts rare?
What are the signs of ACA occlusion?
Medial paracentral gyrus
- Contralateral hemiparesis
- Loss of sensibility in foot and lower extremities
- Urinary incontinence [sometimes]
Prefrontal cortex [possible]
- Cognitive impairment
What artery supplies Wernike’s area?
What artery supplies Broca’s area?
What are the signs of MCA occlusion?
What does the Posterior Cerebral artery supply?
What are the signs of PCA occlusion?
Contralateral Homonymous Hemianopia
Loss of same ½ of field of view in both eyes with sparing of macular vision
- Loss of Temporal visual field
- Loss of Nasal Visual field
Where would a PCA emboli be more likely to infarct?
What structure is implicated in Ruptured Berry Aneurysm?
What % of strokes are due to brain hemorrhages?
Describe the course of the Superior Cerebral veins
Describe the course of the Superficial Middle Cerebral vein
Describe the course of the Inferior Cerebral veins
What veins drain into the superior sagittal sinus?
What structures does the Lenticulostriate arteries supply?
What does the Superior division of the Middle Cerebral artery supply?
What does the Inferior division of the Middle Cerebral artery supply?
What structures are implicated in subdural hemorrhage?
Superior Cerebral Veins
Describe the course of the Internal Cerebral vein
What veins join to form the Internal Cerebral vein?
What veins join to form the Great Cerebral vein of Galen?
Describe the course of the Great Cerebral Vein
Describe the course of the Basal veins
What veins join to form the Basal Veins?
What arteries supply the Midbrain?
What syndromes are implicated when blood supply to the midbrain is implicated?
What arteries supply the pons?
What syndromes are implicated when blood supply to the medulla oblongata is implicated?
What arteries supply the medulla oblongata?
What syndromes are implicated when blood supply to the medulla oblongata is implicated?
What are the most common sites of hemorrhage?
- Basal nuclei
- Thalamus
- Cerebral hemispheres
- Brainstem
- Cerebellum
What are some causes of Primary Intracerebral hemorrhage [PICH]
What vessel is implicated in Subarachnoid hemorrhage?
Cerebral arteries
What vessel is implicated in Epidural Hemorrhage?
What vessel is implicated in Subdural Hemorrhage?
What arteries supply the cerebellum?
AICA [1st of Basilar artery]
PICA [Vertebral artery]
SCA [Final + Largest of Basilar artery]
What are the four lobes of the cerebral cortex?
- Temporal
- Occipital
- Frontal
- Parietal
What structure separates the frontal lobe from the parietal?
Central sulcus
What structure separates the parietal lobe from the temporal?
What structure separates the occipital lobe from the temporal and parietal lobes?
What are the three parts of the Inferior Frontal Gyrus?
What gyri are found on the lateral surface of the cortex?
- Precentral Gyrus
- Postcentral Gyrus
- Superior Temporal Gyrus
- Middle Temporal Gyrus
- Inferior Temporal Gyrus
- Supramarginal Gyrus
- Angular Gyrus
- Superior Parietal Lobules
- Inferior Parietal Lobules
- Superior Frontal Gyrus
- Middle Frontal Gyrus
- Inferior Frontal Gyrus
What sulci are found on the lateral surface of the cortex?
- Superior Frontal Sulcus
- Inferior Frontal Sulcus
- Precentral Sulcus
- Postcentral Sulcus
- Intraparietal Sulcus
- Parieto-occipital Sulcus
- Lateral Occipital Sulcus
- Calcarine Sulcus
- Lunate Sulcus
- Inferior Temporal Sulcus
- Superior Temporal Sulcus
What sulci are found on the medial surface of the cortex?
Cingulate sulcus
Precentral sulcus
Central sulcus
Postcentral sulcus
Parieto-occipital sulcus
What gyri are found on the medial surface of the cortex?
Medial Frontal Gyrus
Paracentral lobule
Cingulate Gyrus
Cuneus
Precuneus
What sulci are found on the inferior surface of the cortex?
- Olfactory sulcus
- ‘H’ shaped sulcus
- Collateral sulcus
- Occipitotemporal sulcus
What gyri are found on the inferior surface of the cortex?
- Orbital Gyrus
- Uncus
- Parahippocampal Gyrus
- Medial occipito-temporal Gyrus
- Lateral occipito-temporal Gyrus
What areas of the cerebral cortex forms the Primary motor area?
What areas of the cerebral cortex form the premotor area?
What areas of the cerebral cortex form the Prefrontal area?
What areas of the cerebral cortex form the Motor Speech centre?
What areas of the cerebral cortex form the Taste area?
What areas of the cerebral cortex form the Primary Auditory area?
What areas of the cerebral cortex form the Auditory Association Area?
What area of the cerebral cortex form the Wernicke’s area?
What area of the cerebral cortex forms the Sensory speech area?
Area 22
What area of the cerebral cortex forms the Primary Visual area?
What areas of the cerebral cortex form the Visual Association Area?
What areas of the cerebral cortex form the Primary Somesthetic area?
What areas make up the Paracentral Lobule?
Contains the primary somesthetic area and primary motor area
- Area 4
- Area 3
- Area 1
- Area 2
What is area 4?
What is the location of Area 4/Primary Motor Area?
Precentral Gyrus and anterior part of the paracentral lobule
What is the location of the supplementary motor area?
What is the function of Area 4/Primary Motor Area?
Individual movements of different parts of the body [motor homunculus] [of simple nature w/o much skill]
Efferent of Primary motor area?
- Premotor area
- Sensory cortex
- Thalamus
- Cerebellum
- Basal nuclei
Afferent of Primary motor area?
- Corticospinal
- Corticonuclear
- Corticopontine
What would a lesion on Area 4 produce?
Hemiplegia
UMNL
What is the premotor area?
Area 6
Area 8
What is the function of the Premotor area?
Carryout complex, skilled or learned movements
Where is the Frontal eye field located?
Middle frontal Gyrus
What is the Frontal Eye Field?
What is the function of the Frontal Eye Field?
What would a lesion in the Frontal Eye Field produce?
- Both eyes deviate to side of lesion
- Inability to turn eyes to opposite side
What would a lesion of the Premotor area produce?
Where is Broca’s area located?
Inferior Frontal Gyrus
What is the function of the Broca’s motor speech area?
Where is the premotor area located?
Where is the writing centre located?
Where is Broadman’s area located?
Where is Wernicke’s area located?
What functional areas are found in the Sensory Speech area?
What does a lesion in the Prefrontal area produce?
- Mental symptoms
- Lack of responsibility in personal affairs
- Vulgarity in speech
- Clownish behavior
What is the function of the Prefrontal area?
- Regulates depth of feeling
- Abstract thinking
- Mature judgement
- Foresight and tactfulness
- Executive function
- Social control
What are the prefrontal areas?
What is the location of the prefrontal area?
Anterior part of superior, middle and Inferior frontal gyrus
Orbital gyrus
Medial frontal gyrus
Anterior part of cingulate gyrus
Where is the location of area 12?
What is area 22?
Wernicke’s area
Sensory speech area
What is the location of Broca’s motor speech area?
Located in left [dominant] hemispheres
Pars triangularis
Pars opercularis
What does a lesion of Broca’s area produce?
Motor aphasia w/preserved comprehension
Connections of Broca’s area
Motor speech area connected with sensory speech area through arcuate fasciculus and primary motor and somatosensory area
What is the function of the Primary Somesthetic area?
Localizes, analyses and discriminates different modalities of sensation
Pain Area
Taste receptive center
Where is the pain area located?
Upper lip of posterior ramus of lateral sulcus along postcentral gyrus
Where is the Taste receptive area located?
Lower part of the postcentral gyrus
Where is the Primary Somesthetic area located?
Postcentral gyrus
Posterior part of the paracentral gyrus
What is the location of Broca’s motor speech area?
Located in left [dominant] hemispheres
- Pars triangularis
- Pars opercularis
What does a lesion of Broca’s area produce?
Motor aphasia w/preserved comprehension
Connections of Broca’s area
Motor speech area connected with sensory speech area through arcuate fasciculus and primary motor and somatosensory area
What is the function of the Primary Somesthetic area?
Localizes, analyses and discriminates different modalities of sensation
Pain Area
Taste receptive center
Where is the pain area located?
Upper lip of posterior ramus of lateral sulcus along postcentral gyrus
Where is the Taste receptive area located?
Lower part of the postcentral gyrus
Where is the Primary Somesthetic area located?
Postcentral gyrus
Posterior part of the paracentral gyrus
Connections of Broca’s area
What is the function of the Primary Somesthetic area?
Where is the pain area located?
Where is the Taste receptive area located?
Where is the Primary Somesthetic area located?
What is Primary Somesthetic area
Afferent to Primary Somesthetic area
Efferent from Primary Somesthetic area
- Thalamus
- Medulla
- SC
- Motor area
- Premotor area
Where is the secondary sensory area located?
Where is the sensory association area located?
What is the sensory association area?
What is the location of area 22?
What is the function of area 22?
What does the lesion of the area 22 produce?
Sensory aphasia [speaks gibberish]
If Wernicke’s + Broca then global aphasia
What is area 17?
Primary Visual Area
Striate area
What is the location of Area 17?
Lips and walls of posterior part of calcarine sulcus
What would a lesion of Area 17 produce?
PCA thrombosis → homonymous hemianopia [w/macular vision sparing]
What structures are connected to the primary visual area?
Temporal part of ipsilateral retina and nasal half of the contralateral one
Macular part of retina, projected into posterior part of area 17
What is the Visual association area?
Area 18
Area 19
What is area 18 called?
Parastriate
What is area 19 called?
Peristriate
What is the function of the Visual association area?
Recognition of objects by relating with past experience
What is area 17?
What is the location of Area 17?
What would a lesion of Area 17 produce?
What structures are connected to the primary visual area?
What is the Visual association area?
What is area 18 called?
What is area 19 called?
What is the function of the Visual association area?
What would a lesion in the Visual association area produce?
What is area 41?
What is the location of area 41?
What does a lesion of area 41 produce?
What is area 42?
What is the location of Area 42?
What is the function of Area 42?
What connections does area 41 receive?
What is the location of Area 40?
What is the function of Area 40?
What does the lesion of Area 40 produce?
What is the location of Area 39?
What is the function of Area 39?
What does a lesion of Area 39 produce?
What is the function of the dominant temporal lobe?
What is the function of the non-dominant temporal lobe?
What is the function of the dominant parietal lobe?
What is the function of the non-dominant parietal lobe?
What is the effect of damage on the frontal lobe?
What is the effect of damage on the non-dominant parietal lobe?
Spatial disorientation
Non-recognition of faces
What is the effect of damage on the dominant parietal lobe?
Dyscalculia
Dyslexia
Apraxia
Agnosia
What is the effect of damage on the non-dominant temporal lobe?
Reception aphasia
Impaired muscle skills
What is the effect of damage on the dominant temporal lobe?
Dyslexia
Verbal memory impaired
Receptive aphasia
What is the effect of damage on the dominant parietal lobe?
What is the effect of damage on the non-dominant temporal lobe?
What is the effect of damage on the dominant temporal lobe?
Dyslexia
Verbal memory impaired
Receptive aphasia
