CNS Anatomy Flashcards
What are the two main types of cells in the CNS and their ratio
Neurons and neuroglia 1:10 ratio
What are the two types of neuroglia
macroglia and microglia
What cells fall under macroglia and what are their characteristics
Astrocytes - helps with the blood brain barrier
Ependymal cells - line the ventricles makes cerebrospinal fluid
Oligodendrocytes and Schwann cells - produce myelin in the CNS and PNS respectively (CoPs)
Describe microglia cells
Macrophages of the nervous system
Derived from Mesoderm not neuroectoderm
Lobes of the brain and their functions and locations
Frontal - Thinking and motor, lies in front of the central sulcus
Parietal - sensory, lies between the central sulcus and the parieto-occipital fissure
Occipital - visual, lies behind the parieto-occipital fissure and preoccipital notch
Temporal - hearing, smell, and memory, lies inferior to the lateral fissure
Describe the different types of white fibers
Commissural: connects right to left cerebral hemisphere ( anterior, posterior, and corpus callosum) and the spinal cord for tracts to decussate
Association: connects one part with another part on the same hemisphere (visual and auditory)
Projection: from brain to spinal cord and vice versa (corticospinal)
What two arterial sources supply the brain
Anterior circulation: internal carotid
Posterior circulation: vertebrobasilar system
What areas does the anterior cerebral artery supply
Medial aspect of the cerebral hemispheres - motor areas 4 and sensory areas 1, 2, & 3
What areas does the posterior cerebral supply
Occipital lobe areas 17, 18, 19, inferior portion of the temporal lobe, midbrain and thalamus
What areas does the middle cerebral artery supply (NOT a part of the circle of willis)
Broca’s area of speech (44 and 45) and the motor and sensory control areas of the face and upper limbs and wernickes area (22)
What does the superior cerebellar artery supply
superior part of the cerebellum
What does the basilar artery supply
pons which contain CN V, VI, VII, and VIII
What does the vertebral artery supply
Medulla whihc contains the nuclei of the last 4 CN: IX, X, XI, and XII
What regulates the blood supply to the brian
Levels of C02, High levels cause vasodilation
Development vesicles of the CN’s
I - talencephalon II - diencephalon III & IV - mesencephalon V-VIII - metencephalon IX-XII - myelencephalon
General functions of the CN’s mnemonic
Severus Snape Meets Malfoy But Mad Bellatrix Stays Behind Bushes Misusing Magic
Describe CN I
Olfactory
CAN regenerate unlike other neurons
Synapses in the primary olfactory cortex located in the temporal lobe which has connections with the hippocampus (memory), hypothalamus (ANS), and limbic (emotions)
ONLY sensory CN not linked initially to the thalamus
Describe CN II
Optic
Fibers synapse in the lateral geniculate body of thalamus
fibers from the thalamus continue as the optic radiation to the primary visual cortex (Brdm 17)
Describe the different Optic lesions and their affects
Optic chiasm - bitemporal hemianopia
Optic nerve - compete loss of vision in side affected
Optic radiation - contralateral homonymous hemianopia
Primary visual cortex - homonymous hemianopia with macular sparing
Describe CN III, IV, and VI (S04 LR6 Rest3)
Extraocular muscles
Occulomotor: Also carries parasympathetic (SVE) fibers to the iris and cilliary body from the edinger-westphal nucleus
CN IV is the only one that exits brainstem dorsally
Describe CN V
Largest mixed CN
Two nuclei: large sensory (GSA) and small motor (SVE)
Where does the motor nucleus of CN V lie and what does it supply
Pons
Supplies muscles of mastication: Temporalis, internal and external pterygoid, masseter, mylohyoid, ANTERIOR BELLY OF THE DIGASTRIC, tensor tympani, and tensor veli palatini
Name the divisions and their branches of CN V
Opthalmic through the superior orbital fissure(NFL) - Nasociliary, Frontal, Lacrimal
Maxillary through the foramen rotundum (PINZ) - Pharyngeal, Infraorbital, Nasopalatine, Zygomatic
Mandibular through the foramen oval:
Anterior division - motor: deep temporal, nerve to lateral pterygoid, and nerve to masseter. Sensory: buccal
Posterior Division - Sensory: lingual, auriculotemporal, inferior alveolar. Motor: muscular branch of mylohyoid
Which ganglion is attached to the opthalmic division of CN V
Ciliary via the nasociliary nerve
It also receives parasympathetic fibers from the edinger-westphal nucleus of CN III
which ganglion is attahed to the maxillary division of CN V
pterygopalatine
It also receives parasympathetic fibers from the superior salivary nucleus of CN VII
which ganglion is attached to the auriculotemporal branch of the mandibular division of CN V
otic
receives parasympathetic fibers from the inferior salivary nucleus via CN IX
Which ganglion is attached to the lingual branch of the posterior division of the mandibular division
submandibular
receives parasympathetic fibers from the superior salivary nucleus of CN VII
What are the nuclei of CN VII and their functions
Motor nucleus in the pons - SVE
sensory nucleus of the trigeminal nerve - GSE
superior salivary nucleus - GVE
solitary tract nucleus - SVA
Describe the motor nucleus of CN VII
Located in the pons Leaves brainstem at pontomedullary angle Enters skull via internal acoustic meatus Leaves skull vai stylomastoid foramen Carries motor fibers to muscles of facial expression via: Temporal zygomatic buccal marginal mandibular cervical (ten zebras bit my mothers chickens)
The strapedius, extrinsic muscles of the ear, and posterior belly of the digastric are innervated by this
CN VII
What portion of the tongue does CN VII convey taste from and with what nerves
anterior 2/3, via the chorda tympani and the nervus intermedius to the nucleus tractus solitarius
Describe the role of chorda tympani branch of CN VII
Receives taste from the anterior 2/3 of the tongue, parasympathetic innervation from the superior salivary nucleus to the submandibular and sublingual salivary glands via the submandibular ganglion of V3 and to the lacrimal gland via pterygopalatine ganglion of V2
Describe the taste sensation distribution of the tongue
sweet - tip of the tongue via VII
salt - sides of tongue via VII
bitter and sour - posterior 1/3 via IX
What are the two distinct parts of CN VIII
cochlear (hearing)
vestibular (balance)
Describe the cochlear part of CN VIII
fibers transverse the internal auditory meatus to the lateral aspect of the medulla
fibers terminate in the dorsal and ventral cochlear nuclei
a majority of fibers then cross to the other side into the nuclei of the trapezoid body
fibers then ascend to the inferior colliculus to the medial geniculate body to the primary auditory cortex (Brdm 22)
Describe the vestibular fibers of CN VIII
arise from semicircular canals (head turning - angular acceleration). utricle, and saccule (gravity - linear accel)
Enter medulla and end in the vestibular nuclei located in the floor of the 4th ventricle
Many of the fibers pass to the cerebellum through the infeiror cerebellar peduncle
Where doe CN IX motor fibers arise from and what do they supply
nucleus ambiguus to the stylopharyngeus (SVE)
What innervation does CN IX provide for the tongue
Sensation from the posterior 1/3 and pharynx via sensory nucleus of CN V
Carries taste from the posterior 1/3 of the tongue to the nucleus solitarius in the medulla
What parasympathetic innervation does CN IX supply
parasympathetic to the parotid gland via otic ganglion of V3 from the inferior salviary nucleus in the medulla
What opening does CN IX leave the skull
jugular foramen
Describe the carotid branch of CN IX
runs along internal carotid and supplies the carotid body (chemoreceptor) and carotid sinus (baroreceptor)
Describe CN X
Leaves brain stem in the groove between the oliv and cerebellum.
Exits through jugular foramen giving off the tympanic branch
It travels between the superior and middle constrictors supplying the root of the tongue, tonsils and muscles and mucosa of pharynx.
Carries parasympathetic information to the thorax and abdomen as far as the transverse colon
also carries sensory from thorax and abdomen
ratio of afferent to efferent is 10:1
What are the two parts of CN XI and their features
Cranial accessory: SVE, joins spinal part before passing through jugular foramen, after the foramen it joins the vagus to supply the palate, pharynx, and larynx
Spinal accessory: GSE, arises from 5 upper cervical rootlets, they join together and enter the skull though the foramen magnum, after exiting it pierces and supplies the SCM, then passes through the posterior triangle piercing and supplying the trapezius
Describe CN XII
ALL of the muscles of the tongue are supplied by the hypoglossal EXCEPT palatoglossus (pharyngeal plexus of vagus)
Begins as rootlets between the pyramid and olive in the medulla.
Exits via hypoglossal foramen
Passes between internal carotid and internal jugular vein
It then loops and crosses the hyoglossus muscle to enter the tongue
Describe the internal capsule
IMPORTANT
anterior limb - lies between caudate nucleus and lentiform, carries thalamocortical fibers (sensory below head)
Genu - carries corticobulbar fibers (motor fibers to the head)
posterior limb - between lentiform and thalamus, carries corticospinal tract (motor below the head, Auditory and visual association fibers and thalamocrtical fibers
What is the role of the thalamus in the internal capsule
acts as a relay station for all snsory input into the cortex EXCEPT olfaction
Describe the basal ganglia
Composed of the globus pallidus, putamen, and caudate nucleus
controls complex patterns of voluntary behavior
Blood supply to the internal capsule
anterior - anterior and middle cerebral arteries
genu - middle cerebral artery
posterior - middle cerebral and anterior choroidal a
Describe the thalamus
Major transit area for ALL sensory input EXCEPT from the olfactory
VPL nucleus - input from the neck and below
VPM nucleus - input from the head
Lateral geniculate body - visual input (Light) connects with superior colliculous
Medial geniculate body - auditory input (Music) connects with inferior colliculous
Describe the basal ganglia
Influence the motor activity of the brain though inhibition or facilitation
Composed of the caudate nucleus, lentiform nucleus, and substantia nigra .
Describe the 3 peduncles of the cerebellum
Superior - output to the cerebral cortex via the midbrain and thalamus
middle - input from the cortex via the pons with the cortico-ponto-cerebellar fibers
inferior - input from the body via the medulla carrying the dorsal spinocerebellar
Describe the 3 main nuclei of the cerebellum (Flowers Grow Every Day - medial to lateral)
Fastigial - related to the spine
Globose - related to the proximal joints (Glenohumeral)
Emboliform - related to middle joints (elbow)
Dentate - related to distal joints (digital)
Describe the 3 lobes of the cerebellum
anterior - balance of arms and legs
posterior - receives information from the cortex
flocculonodular - balance of the trunk
Describe the blood brain barrier
Formed by: tight junctions between non-fenestrated capillary endothelial cells, basement membrane and the processes of astrocytes
oxygen, carbon dioxide, glucose and AA’s freely cross
Bacteria can not cross
What areas contain fenestrated areas and no BBB
area prostrema - which facilitates vomiting in response to poisons
neurohypophysis and pineal gland for secretion of hormones
Describe the vertebral artery and its different parts
Derived from the subclavian artery
Part 1 - lies between it’s origin and the 1st part of the subclavian artery to transverse foramen of c6
Part 2 - lies between transverse foramina of C6 to C1, relatively fixed
Part 3 - Extends from c1 to the foramen magnum, most prone to dissection,
Part 4 - section lying above foramen magnum, lies anterior to medulla
Describe PICA (wallenberg or lateral medullary) syndrome
Occlusion of the posterior inferior cerebellar artery
dysphagia, ataxia, ipsilateral horner’s syndrome,
*ipsilateral loss of pain and temperature in the face and contralateral loss of pain and temperature of the body below head
Describe medial medullary syndrome
occlusion of the vertebral artery
contrlateral spastic hemiplegia, loss of touch, and vibration and pressure
Describe Clause’s syndrome
occlusion of the blood supply to the dorsal midbrain
ipsilateral CN III palsy and contralateral ataxia and tremor
Describe Weber (medial midbrain) syndrome
occlusion of perforating branches posterior cerebral artery
contralateral spastic paralysis and ipsilateral CN III weakness
What and where is CSF produced
Produced by choroid plexus in the lateral ventricles
Describe CSF flow
Produced in lateral ventricle and passes through the foramina of Monro into the third ventricle it then passes through the cerebral aqueduct of sylvius into the 4th ventricle, it then leaves the 4th ventricle via the lateral foramina of Luschka and the median foramen of Magendie
How does CSF drain
Drains via arachnoid granulations which open into thesuperior sagittal sinus
Describe the superior sagittal dural venous sinus
Found in the attached edge of the flax cerebri
drains into the right transverse sinus which lies in the tentorium cerebelli
Describe the inferior sagittal dural venous sinus
found in the free edge of the falx cerebri
Joined by the great cerebral vein of Galen to drain into the straight sinus which empties into the left transverse sinus
