ANAT242 M1 L2- Flashcards
What are the 4 types of nerve tissue?
Astrocytes, oligodendrocytes, microglia and ependymal cells
What is white matter composed of?
Axons
White due to myelin
What is gray matter composed of?
Neuron cell bodies (soma)
Nucleus in CNS
Ganglion in PNS
What is a gyrus?
Turn or twist in brain
Identified by a hilly bump
What is a sucli?
Valley, groove that goes inwards
What is a fissure?
Separates large regions of the brain
What is the insula?
Buried deep in lateral sulcus
Covered by portions of temporal, parietal and frontal lobes
What separates the frontal and parietal lobes?
Central sulcus
What separates the cerebrum from the cerebellum?
Transverse fissure
What separates the temporal lobe from the parietal and frontal?
Lateral sulcus
What separates the parietal and occipital lobes?
Parieto-occipital sulcus
What is the bottom of the spinal cord called?
Conus medullaris (L1-L2)
What is the filum terminale?
Extends from conus medullaris to posterior surface of coccyx
What is the cauda equina?
Collection of nerve roots at inferior end of vertebral canal
Why do nerve roots extend past the length of the spinal cord?
Due to disproportionate growth of spinal cord vs vertebral column
What is paresthesias?
Sensory loss (white matter)
Damage to what vertebrae causes high tertraplegia?
C1-C4
Damage to what vertebrae cause low tetraplegia?
C5-C8
Damage to what vertebrae causes paraplegia?
Thoracic, lumbar, sacral
What are the 3 layers of meninges?
Dura mater
Arachnoid mater
Pia mater
What are properties of the dura mater?
Very strong and durable
Thick layer of CT
What are the two layers of the dura mater?
Periosteal and meningeal
What is the purpose of the periosteal and meningeal layers of the dura mater?
Separate and form large dural venous sinuses
What is the tentorium cerebelli?
Meningeal layer that separates cerebrum from cerebellum (tent)
What is the falx cerebri?
Small dural fold, runs along midline of cerebellum
Separates two cerebellar hemispheres
What is the subdural space?
Between meningeal dura mater and arachnoid mater
Contains a film of fluid
Bleeding causes subdural haemorrhage
What is the arachnoid mater?
Delicate transparent membrane
Does NOT go into sulci
Connected to pia mater by fine strands of CT
What is the subarachnoid space?
Between arachnoid mater and pia mater
Wide space filled w/ CSF
Blood In here = subdural haemorrhage
What are the arachnoid villi?
Projections of the arachnoid mater
Can form arachnoid granulations
Drain CSF into venous sinuses
What are cisterns?
Enlarged subarachnoid space that accumulates CSF
What are the different cisterns?
Cerebellomedullary = largest
Superior cistern = superior to cerebellum
Interpenduncular cistern
Pontine cistern
What is the pia mater?
Delicate, follows contours of brain
Surrounds blood vessels
Forms perivascular space
Forms roof of ventricles
Why does the spinal meninges not have a periosteal layer of the dura mater?
Due to requirement of spinal mobility
What is the epidural space?
Between spinal dural sheath and vertebral bony wall
Contains fat and venous plexus
Largest at L2
What is the subarachnoid space?
Between arachnoid and pia mater
Contains CSF
What is the lumbar cistern?
Inferior to spinal cord L1
Where lumbar puncture occurs
What is the denticulate ligament?
Support spinal cord within dural sheath
Lateral anchoring and support
What does the filum terminale do?
Anchor spinal cord in vertical direction
What are the symptoms of meningitis?
Inflammation of pia-arachnoid
Fever, headache, stiff neck
CSF presents cloudy due to bacteria
What is included in the ventricular system?
4 ventricles
2 lateral, 3rd and 4th
Contains CSF and continuous with each other
What is the cerebral aqueduct?
Connects 3rd and 4th ventricles
What is the interventricular foramen and lateral aperture?
Ensure continuity of lateral ventricles
Where do the lateral ventricles go?
Frontal -> anterior horn
Occipital -> posterior horn
Temporal -> inferior horn
Choroid plexus circulates CSF around body and inferior horn
What does the 3rd ventricle do and where is it?
Seen in between thalamus
Between lateral ventricle and cerebral aqueduct
Choroid plexus in roof
Where is the 4th ventricle?
Lies between cerebellum, pons and medulla
3 openings - 2 lateral (luschka), 1 median (magendie)
What is the flow of CSF?
Choroid plexus -> lateral ventricle and 3rd ventricle
Cerebral aqueduct -> 4th ventricle
Goes down to cerebellomedullary cistern, down spinal cord and circulates up
Goes into arachnoid granulations and eventually superior sagittal sinus
What is hydrocephalus?
Water on the brain characterised by excessive CSF in ventricular system
Can cause englarged heads for new borns
What % of bloodflow is directed to the brain?
15% of blood flow is for the brain
1-2 min = impaired function
4 min = irreversible damage
What is the track of the anterior blood supply?
Common carotid artery splits to internal and external carotid artery
What is the track of the posterior blood supply?
Vertebral artery (in column) split into 2 and then join to 1 - basilar artery
What does the basilar artery divide into?
Basilar divides into 2 posterior cerebral arteries
What does the internal carotid artery branch into?
Anterior and middle cerebral artery
What is the circle of willis?
Basilar artery connects to internal carotid via posterior communicating arteries
What is the purpose of the circle of willis?
Maintain supply to entire brain if 1 main artery is blocked or narrowed
What does the posterior cerebral artery supply?
Occipital lobes, brainstem, medial aspect of hemisphere (posterior 1/3), 3rd and lateral ventricles and inferior temporal lobes
What does the middle cerebral artery supply?
Almost all lateral surfaces of hemispheres
What does the anterior cerebral artery supply?
Supply the anterior 2/3 of medial hemisphere and basal nuclei
What happens when there is an occlusion of the anterior cerebral artery?
Contralateral hemiplagia (1 artery) or bilateral paralysis (2) and impaired sensation
Greatest in lower limb
What happens when there is an occlusion of the middle cerebral artery?
Severe contralateral hemiplagia and impaired sensation
Most marked in upper limb and face
Severe aphasia if dominant hemisphere affected
What happens when there is an occlusion of the posterior cerebral artery?
Contralateral homonymous hemianopsia
What is contralateral homonymous hemianopsia?
Opposite side vision problems
What forms the roof of the 4th ventricle?
Superior medullary velum
What is the path of venous drainage in the brain?
Fine veins (brain) -> pial venous plexuses -> cerebral veins -> dural venous sinuses -> internal jugular vein -> heart
Where are the venous sinuses located?
Between periosteal and meningeal layer
Receive venous blood from brain and scalp as well as CSF
Purpose and anatomy of superior saggital sinus
Lies along superior margin of the falx cerebri
Joins the transverse sinus (right)
Arachnoid villi drain the CSF into the sup. sagittal sinus
Purpose and anatomy of inferior sagittal sinus
Lies along inferior margin of the falx cerebri
Joins the straight sinus
Purpose and anatomy of straight sinus
Within tentorium cerebelli
Joins left transverse sinus
Purpose and anatomy of transverse sinus
Left continuous w/ straight sinus
Sinuses join at confluens
Purpose and anatomy of sigmoid sinus
Forward continuation of transverse sinus
Opens into internal jugular vein
Purpose and anatomy of cavernous sinus
Lateral to pituitary gland, linked w/ venous channels
Drains into superior and inferior petrosal sinuses
What is contained in the frontal lobe?
Anterior of central sulcus
Incl. pre-central gyrus, sup., middle and inferior frontal gyrus
Superior and inferior frontal sulcus
What is in the inferior frontal gyrus?
Opercular most posterior
Triangular in middle
Orbital most anterior near eye
What is contained in brocas area?
Opercular and triangular
Usually present in left hemisphere
What is contained in the pre-central gyrus?
Somatic motor cortex
Area of cortex to specific region proportional to amount of motor control over that region
What happens when there is damage to the pre-central gyrus?
Depending on whether its anterior or middle cerebral artery blocked is contralateral hemiplagia and lower limb, middle is same and upper limb + face
What is the pre-motor cortex?
Anterior to pre-centra gyrus
Controls learned motor skills
Supplies 30% of pyramidal tract axons
Damage results in loss of skills
What are the supplementary and cingulate motor areas?
Supplementary anterior to pre-central gyrus
Cingulate covers top of corpus callosum
Receives input from many other cortical areas and thalamus
Contribute to cortiocospinal tract
What happens when there is damage to the supplementary and cingulate motor areas?
Loss of desired skill movement and speech
What does the parietal lobe do?
Integrates sensory info
What is the anatomy of the parietal lobe?
In post-central gyrus
Sup. and inf. parietal lobule separated by intraparietal sulcus
Where are the supramarginal and angular gyrus located?
Supramarginal gyrus posterior to post-central gyrus
Angular gyrus posterior to supramarginal gyrus
What is the purpose of the post-central gyrus?
Also known as somatosensory cortex
Receive info from contralateral side
What is the somatosensory association cortex?
In the sup. parietal lobule
Integrating different sensory inputs via somatosensory cortex
Ie: limb positioning, weight and texture of object, location of touch and pain
What is the anatomy of the occipital lobe?
Posterior to parieto-occipital sulcus
Calcarine sulcus separates - primary cortex inferior
Secondary on either side of primary visual cortex
What is the visual association area?
Communicates w/ primary visual cortex
Interprets visual stimuli
Face recognition in temporal lobe
What is the anatomy of the temporal lobe?
The sup. and inf. temporal sulcus divide it into sup., middle and inf. frontal gyrus
Rhinal sulcus anterior
Collateral posterior to rhinal
Occipitotemporal lateral to other 2
Uncus medial to rhinal
Parahippocampal gyrus medial to collateral
Inf. temporal gyrus later to occipitotemporal sulcus
What does the fimbria do?
Connect the hippocampi to other structures
What is the septum pellucidum?
Separates the two ventricles
What connects the hippocampi to other structures?
Fimbria –> fornix
What is the transverse temporal gyri?
Primary auditory cortex
Wernickes area superficial and posterior
What is the insular lobe for?
Emotion, homeostasis, cognition and being self-aware
What is non-fluent aphasia?
Brocas area damage
Can comprehend speech but difficult to produce - little fluency
What is fluent aphasia?
Wernickes area damage
Difficult to comprehend speech and talking is fluent but meaningless
What is contained in cerebral white matter?
Consists largely of myelinated axons bundled into large tracts
What are projection tracts?
Extend top -> bottom
Vertically from brain -> spinal cord forming internal capsule
What are commissural tracts?
Cross hemispheres
Involves corpus callosum, wide band of axon tracts
What is the anatomy of the corpus callosum?
Rostrum 1st part close to nose
Genu = first turn (in frontal lobe)
Body = main part (frontal/parietal)
Splenium = most post. (temp/occipital)
What is contained in the anterior commissure?
Axons that connect middle and inferior temporal gyri of 2 sides
What do cerebral white matter association fibres do?
Connect lobes and gyri w/ in hemisphere
What is contained in the basal ganglia?
Caudate nucleus, putamen, globus pallidus, subthalamic nuclei and substantia nigra
What is contained in the lentiform nucleus?
Putamen and globus pallidus
What is contained in the striatum?
Caudate nucleus and putamen
What does the caudate nucleus look like?
C - shaped
What is the foramen and function of the olfactory nerve (I)?
Foramen = Cribriform plate
Function = Olfaction - sensory
What is the foramen and function of the optic nerve (II)?
Foramen = Optic foramen
Function = Vision - sensory
What is the foramen and function of the occulomotor nerve (III)?
Foramen = Superior orbital fissure
Function = Innervate most eye muscles - motor
What is the foramen and function of the trochlear nerve (IV)?
Foramen = Superior orbital fissure
Function = Eye movement - motor
What is the foramen and function of the trigeminal nerve (V)?
Foramen = V1, sup. orbital fissure,
V2, Foramen rotundum
V3, Foramen ovale
Function = V1,2,3 sensory from eye, V3 innervates mastication muscles
What is the foramen and function of the abducens nerve (VI)?
Foramen = Superior orbital fissure
Function = Abducts eye - motor
What is the foramen and function of the facial nerve (VII)?
Foramen = Internal acoustic meatus and stylomastoid foramen
Function = muscles of facial expression and taste from anterior 2/3 of tongue - both
What is the foramen and function of the vestibulocochlear nerve (VIII)?
Foramen = Internal acoustic meatus
Function = Hearing and balance - sensory