Neuroanatomy Practical 3 Flashcards
Lateral view of cerebral hemisphere (frontal pole on the right)
What structure is hidden between the temporal and parietal lobes? What fissure/sulcus is it located in?
Insula: portion of the cerebral cortex folded deep within the lateral sulcus (the fissure separating the temporal lobe from the parietal and frontal lobes) within each hemisphere of the mammalian brain.
Function of insula (N.B. part of lobe been removed in photo)
processes information associated with hearing and equilibrium
What is being pointed to? (lobes have been removed)
Insula
Which foramina connect each lateral ventricle to the 3rd ventricle?
Interventricular foramen / foramen of Monro
Where does the 3rd ventricle sit?
The diencephalon encloses the third ventricle (thalamus either side)
Which structure sits either side of the 3rd ventricle?
Thalamus
Which structure is being pointed to? Function?
The interthalamic adhesion (also known as the intermediate mass or middle commissure) is a flattened band of tissue that connects both parts of the thalamus at their medial surfaces
Which foramen connects the 3rd and 4th ventricle?
Cerebral aqueduct
Which structures sit anterior and posterior to the 4th ventricle?
Pons anteriorly and cerebellum posteriorly
What is the 4th ventricle continuous with?
The central canal of the medulla and spinal cord
Where does CSF escape into subarachnoid space?
From 4th ventricle via foramen of Lushka (x2) laterally and foramen of Magendie (x1) medially/posteriorly
What brain region contains the cerebral aqueduct?
Midbrain
View of dorsal aspect of 4th ventricle behind pons
This is the hippocampus (one on right and one on left). Where does it sit? Function?
Sits in temporal lobe –> memory
Describe shape of hippocampus
Sends fibre bundle (fornix) with characteristic C-shape as it arches over the thalamus to end up in the hypothalamu
What is the fornix?
The fornix is a C-shaped bundle of nerve fibers in the brain that acts as the major output tract of the hippocampus. The fornix also carries some afferent fibers to the hippocampus from structures in the diencephalon and basal forebrain. The fornix is part of the limbic system.
Describe location of hippocampus and fornix
- Sits inferior to inferior horn of lateral ventricle in the temporal lobe
- Fornix sits medial to lateral ventricles and arches over thalamus to end in the hypothalamus
What does the fornix connect to?
Mamillary bodies of hypothalamus
What is found lateral to the thalamus?
Fibres of internal capsule
What does the internal capsule contain?
Ascending (sensory) and descending (motor) fibres
What is the internal capsule found medial to?
Lentiform nucleus
What composes the lentiform nucleus?
- Putamen (laterally)
- Globus pallidus (medially)
View of caudate nucleus
- C-shaped exterior of caudate nucleus; head, body and tail
- Lentiform nucleus in middle
The caudate nucleus and the putamen share some connections. What are these called?
Cellular bridges
Together, the caudate nucleus and lentiform nucelus form what structure?
Corpus striatum
What interrupts the cellular bridges?
Some fibres of internal capsule
What is found superior to fornix (between lateral ventricles)?
Corpus callosum –> major cerebral commissure
What is being pointed to?
The amygdala is one of two almond-shaped clusters of nuclei located deep and medially within the temporal lobes of the brain’s cerebrum (anterior to hippocampus)
Where is the primary visual cortex located?
Posterior pole of occipital lobe
Where is the primary auditory cortex located?
Superior temporal gyrus
What is Broca’s area?
a region in the frontal lobe of the dominant hemisphere, usually the left, of the brain with functions linked to speech production located in the ingerior frontal gyrus
What is the calcarine sulcus?
Subdivides the occipital lobe superiorly and inferiorly
Fornix drawn in blue
Which 2ary brain vesicle do the mamillary bodies belong to?
Diencephalon
Which 2ary brain vesicle does the thalamus belong to?
Diencephalon
Which 2ary brain vesicle does the caudate nucleus belong to?
Telencephalon
Which 2ary brain vesicle does the corpus callosum belong to?
Telencephalon
A patient exhibits a variety of behavioural and language problems such as a failure to inhibit responses that are socially inappropriate. Such an individual is most likely to suffer from dementia involving the:
a) parieto-occipital region
b) prefrontal cortex
c) inferior temporal cortex
d) corpus callosum
Prefrontal cortex; planning complex cognitive behavior, personality expression, decision making, and moderating social behaviour
A 79 year old woman is admitted to ER after she was found unconscious in her apartment. After she regained consciousness, a neurological examination indicated that she suffered a stroke with paralysis of the right arm and leg as well as loss of speech.
The loss of speech in this patient was due mainly to damage of the:
a) superior frontal cortex
b) inferior temporal gyrus
c) inferior frontal gyrus
d) superior temporal gyrus
Loss of speech; damage to inferior frontal gyrus (Broca’s area found here)
A 35 year old man suffered a stroke that did not cause paralysis. However, he discovered that he was unable to perform complex learned movements.
The region of the cerebral cortex most likely affected by the stroke was the:
a) precentral gyrus
b) postcentral gyrus
c) premotor cortex
d) prefrontal cortex
Premotor cortex; an area of the motor cortex lying within the frontal lobe of the brain just anterior to the primary motor cortex.
What is this sulcus? What is found anterior and posterior?
Central sulcus;
- anterior is frontal lobe and precentral gyrus
- posterior is parietal lobe and postcentral gyrus
What area is being pointed to?
Broca’s area
Premotor cortex, Broca’s area and prefrontal cortex
What is this? What cortex is located here?
Superior temporal gyrus –> primary auditory cortex
What is this?
Optic chiasma
What are these?
Mamillary bodies (parts of hypothalamus)
What is this?
Pituitary stalk/infundibulum –> close relationship with optic chiasma
Which structure can pituitary tumours compress?
Optic chiasma –> visual deficits
What is being pointed to?
Substantia nigra of midbrain
What is this?
Mamillary body belonging to hypothalamus
What is this?
Hypothalamus
What is this?
Thalamus
What is this?
Corpus callosum
What is this?
Lateral ventricle
What c-shaped strip of cortex is located parallel to corpus callosum?
Cingulate gyrus (part of limbic lobe)
Which sulcus is found superior to the cingulate gyrus?
Cingulate sulcus
What is the cingulate gyrus continous with inferiorly (in the temporal lobe)?
Parahippocampal gyrus (part of limbic lobe)
What sulcus is this?
Parieto-occipital
What sulcus is this?
Calcarine sulcus
Which cortex surrounds the calcarine sulcus?
Primary visual cortex
A patient reported a sudden loss of all forms of sensation on the left side of the body. Where is the lesion?
a) right lateral hypothalamus
b) right medial hypothalamus
c) right lateral thalamus
d) right cingulate cortex
right thalamus; contralateral innervation (VPL)
What is septum pellucidum?
The septum pellucidum is a thin, triangular, vertical double membrane separating the anterior horns of the left and right lateral ventricles of the brain –> i.e. between the 2 cerebral hemipsheres
What does the hypothalamic sulcus separate?
Thalamus from hypothalamus
How is the uncus formed?
The uncus is an anterior extremity of the parahippocampal gyrus (forms a hook)
What is this?
Pituitary gland
What is this?
Pineal gland
What is this?
Lateral ventricle
What foramen is this?
Interventricular foramen
The putamen, caudate nucleus and globuls pallidus together form what?
The corpus striatum; are part of the basal nuclei (ganglia)
The putamen, caudate nucleus and globuls pallidus are part of the telencephalon or diencephalon?
Telencephalon
Label a b and c
a - head of caudate nucleus
b - putamen
c - globus pallidus
Label a b and c
a - head of caudate nucleus
b - putamen
c - globus pallidus
Which one of the following arteries supplies parts of the caudate nucleus, putamen and internal capsule?
a) Anterior communicating arteries
b) Anterior inferior cerebellar arteries
c) striate arteries
d) vertebral arteries
Striate arteries
Patient was admitted to the emergency room complaining of headaches. Further examination revealed certain motor dysfunctions characterised by involuntary movements at rest. Analysis indicated that the patient had a tumour located near the lateral wall of the anterior horn of the lateral ventricle.
The deficit was most likely due to impingement of the tumour on the:
a) caudate nucleus
b) putamen
c) globus pallidus
d) cingulate gyrus
Caudate nucleus; head of caudate is lateral to the anterior horn of the lateral ventricle
What is this?
Choroid plexus of the lateral ventricle
What is this?
Anterior horn of lateral ventricle
What is this?
Posterior horn of lateral ventricle
What is this?
Corpus callosum
Which forms the floor of the longitudinal fissure?
Corpus callosum
What is the front part of the corpus callosum called?
Genu; curves downward and backward in front of the septum pellucidum, diminishing greatly in thickness
Genu of corpus callosum in horizontal slice
What is this aspect (posterior) of the corpus callosum?
Splenium
View of splenium of corpus callosum (closely related to posterior horn of lateral ventricle)
What is this structure lateral to anterior horn of lateral ventricle?
Head of caudate nucleus
What is this deep grey matter structure?
Head of caudate nucleus (lateral to anterior horn of lateral ventricle)
View of grey and white matter
What is this?
head of caudate nucleus
What structure surrounds the 3rd ventricle?
Thalamus either side
What is found lateral to thalamus (and caudate nucleus)?
White matter fibres; internal capsule
What grey matter structures are found lateral to the internal capsule?
Putamen and globus pallidus
What is this the edge of?
Insula
What type of fibres is the corpus callosum classified as?
Commissural; connect right and left hemispheres
What type of fibres is the internal capsule?
Projection; connect cerebrum with lower centres
What type of fibres is that our arcuate fasciculus (connects Broca’s area and Wernicke’s area)?
Association; connect areas within a hemisphere
Label a b and c
a - anterior limb of internal capsule (lateral to head of caudate)
b - genu of internal capsule
c - posterior limb of internal capsule (lateral to thalami)
What is the anterior limb of the internal capsule lateral to?
Head of caudate nucleus
What is the posterior limb of the internal capsule lateral and medial to?
Lateral to thalamus and medial to putamen
What white fibres are being pointed to? Function?
Optic radiation; axons from the neurons in the lateral geniculate nucleus to the primary visual cortex (posterior pole of occipital lobe).
What type of fibres are found in the internal capsule?
Projection fibres; both afferent and efferent
Where do the afferent fibres of the internal capsule pass?
From cell bodies of the thalamus to the cortex
Where do the efferent fibres of the internal capsule pass?
From cell bodies of the cortex to the cerebral peduncles of the midbrain
Where does fornix start/end?
Hippocampus sends an afferent fibre bundle (fornix) that arches over the thalamus to end up in the mamillary bodies of the hypothalamus
During what appeared to be routine surgery for a torn ligament, a middle-aged man suffered a stroke. After a few days, the patient showed some recovery because he was able to walk with some difficulty, and, in addition, sensory functions seemed normal. However, A neurologic evaluation revealed a weakness in muscles that regulate breathing, speech, swallowing, and facial expression.
A subsequent magnetic resonance imaging scan indicated that the stroke was limited but primarily affect the:
a) anterior limb of internal capsule
b) genu of internal capsule
c) posterior limb of internal capsule
d) medullary pyramids
Walking; motor function to legs is ok
Sensory; posterior limb of internal capsule is ok
Motor fibres that go towards head run in the genu of the internal capsule to cranial nerve nuclei in brainstem –> b)
Function of the:
a) anterior limb
b) genu
c) posterior limb
of the internal capsule?
anterior limb:
- carries thalamic and brainstem fibers from prefrontal cortical regions that are associated with different aspects of emotion, motivation, cognition processing, and decision-making
genu:
- formed by fibres from the corticonuclear tracts
- originate in the motor part of the cerebral cortex and after passing downward through the base of the cerebral peduncle with the cerebrospinal fibers, undergo decussation and end in the motor nuclei of the cranial nerves of the opposite side
- It contains the corticobulbar tract, which carries upper motor neurons from the motor cortex to cranial nerve nuclei that mainly govern motion of striated muscle in the head and face.
posterior limb:
- The anterior two-thirds of the occipital part of the internal capsule contains fibers of the corticospinal tract
- arise in the motor area of the cerebral cortex and, passing downward through the middle three-fifths of the base of the cerebral peduncle, are continued into the pyramids of the medulla oblongata.
- The posterior third of the occipital part contains sensory fibres
A 68 year old man is admitted to the emergency room after initially complaining of dizziness. In the emergency room, the patient indicated that he could not move his right arm or leg, and his speech was slurred. The tongue was directed to the right side when the patient was asked to protrude it, and the patient’s jaw drooped to the right side as well. Sensory functions on each side of the body appeared normal as well as motor functions on the left side.
The patient sufferent a stroke involving the:
a) anterior cerebral artery
b) middle cerebral artery
c) posterior cerebral artery
d) anterior spinal artery
The stroke involved the:
a) right precentral gyrus
b) right internal capsule
c) left internal capsule
d) left medullary pyramids
- Middle cerebral artery; somatotopic organisation of precentral gyrus (deficits of face and arms is more lateral –> territory of MCA)
-
Left internal capsule
- Descending fibres for right side of body take origin in left precentral gyrus
- Fibres then pass through internal capsule
- Caudally in medulla, these fibres decussate (decussation of pyramids)
- UMNs for tongue only innervate contralateral nuclei (not bilateral innervation) –> see lectures
- Trigeminal nuclei innervation is bilateral (hence weakness of jaw, not paralysis)
- Descending fibres for right side of body take origin in left precentral gyrus
