Neuro Anatomy Flashcards
Median/Sagittal Plane
Vertical plane passing through sagittal suture of skull
Planes parallel to the Sagittal plane are called…
Parasagittal planes
Rostral vs Caudal direction
Rostral - towards nose
Caudal - towards tail
Brain is divided into 3 parts
Hindbrain (rhombencephalon)
Midbrain (mesencephalon)
Forebrain (prosencephalon)
Cerebellum responsible for…
Motor control of equilibrium, posture, muscle tone, movement co-ordination
Brainstem comprises…
Ascending and descending tracts, cranial nerve nuclei and reticular formation
Gyri
Rolls of cerebral cortex
Sulci
Grooves between gyri
Central Sulcus
Large groove separating frontal from parietal lobes
Lateral Sulcus
Large fissure separating temporal lobes from parietal and frontal lobes
Insula
Forms floor of the lateral sulcus
Functions include disgust, self-awareness, emotion
Opercula (lips)
Parts of temporal, parietal and frontal lobes that overlie the insula
Ventral =
Dorsal =
Anterior
Posterior
What is the Corpus callosum?
Large bundle of white matter connecting the 2 hemispheres
Where do the olefactory tracts run?
Inferior surface of frontal lobes
Grey vs white matter
Grey - Lots of cell bodies
White - Axons, myelin sheath, some Glial cells
Hindbrain (rhombencephalon) comprises…
Pons and Medulla
Association fibres
Stay in same hemisphere they start in
Commissural fibres
Connect between L and R hemispheres
Projection fibres
Carry info from spinal cord up into cortex and back down from cortex into spinal cord
Role of frontal lobes
Motor function, memory, language, judgement
Motor cortex
Region of cerebral cortex responsible for signalling for movement
Size of cortex responsible for a part of the body is relative to the complexity of movement at that part (e.g- area dedicated to thumb similar to area dedicated to trunk even though trunk is much bigger)
Role of temporal lobes
Language, memory, meaning of things, facial recognition
Role of parietal lobes
Somatosensory
Dominant (usually left): perception, language, maths
Non dominant (usually right): visuospatial function
Role of occipital lobes
Visual
CSF in the skull sits between…
Pia mater and Arachnoid mater
Asymmetry of brain
R frontal and L occipital lobes protrude outwards more than their counterpart
Occipital poles
Posterior-most parts of occipital lobes
Optic nerves location
Pass backwards and medially converging in midline to form optic chiasma
Then pass backwards and laterally as the optic tracts
Mammillary bodies
2 rounded eminences behind the optic chiasma
Hypothalamus location
Behind optic chiasma up to and including the mammillary bodies (only part of diencephalon visible on outside of brain)
Cerebral peduncles
2 stalks attaching cerebrum to brainstem
Crus cerebri (plural = crura cerebri) of the cerebral peduncles
2 large masses of white matter emerging behind the mammillary bodies on each side
They pass backwards converging with midline of pons
Interpenduncular Fossa
Space between crura roofed over by arachnoid
Pons position in relation to crura
Situated immediately behind where crura meet in midline
What joins the 2 hemispheres of the cerebellum?
Central Vermis
Prefrontal cortex vs posterior portion of frontal lobe
Prefrontal cortex - Higher cognitive functions, determinants of personality
Posterior portion - motor and premotor areas
Broca’s Area
In left inferior frontal gyrus
Important in language production and comprehension
Wernicke’s Area
In superior temporal gyrus of L hemisphere
Concerned with understanding spoken word
Limbic lobe contains…
Hippocampus, fornix, amygdala
3 meningeal layers
Dura mater
Arachnoid mater
Pia mater
Dura mater layers
Outer endosteal layer - lines interior skull, adhering to, and sending blood vessels into cranial bones
Inner meningeal layer - envelopes CNS and continues as tube of dura around spinal cord and provides tubular sheaths for cranial nerves
Dural venous sinuses
Communicating blood filled spaces where the 2 dura layers have separated and folded over
Tentorium Cerebelli
Dura forming a thick fibrous roof over the posterior cranial fossa and the cerebellum
Straight sinus
Within tentorium cerebelli at its attachment to the falx cerebri
Transverse sinuses
Run along line of attachment of tentorium cerebelli to occipital bone
Cavernous sinus location
Lies lateral to body of the sphenoid
Trigeminal cave
Lies next to apex of petrous part of temporal bone and envelopes roots of the trigeminal nerve
Diaphragma sellae
Fold of dura mater which forms roof of pituitary fossa
Falx cerebelli
Small, vertical sickle-shaped reflection of dura separating the 2 lobes of the cerebellum
Foramen of Magendie role
Midline communication between IVth ventricle and subarachnoid space
Foramen of Lushka role
Lateral communication between IVth ventricle and subarachnoid space
Subarachnoid cisterns
Spaces between arachnoid and pia mater (pools of CSF)
Blood brain barrier
On brain surface, arteries lie in subarachnoid space. As vessels pass into brain, they’re surrounded by prolongations of pia mater and some subarachnoid space which thins towards the capillaries (at this point pia and BM of endothelial cells fuse)
Arterial blood to the brain arrives within the skull via 2 pairs of vessels…
-Internal Carotid Arteries
-Vertebral Arteries
Internal Carotid Arteries supply…
-Anterior and Middle Cerebrum
-Diencephalon
Vertebral Arteries supply…
-Posterior Cerebrum
-Contents of Posterior Cranial Fossa
Path of Internal Carotid Artery
Arises at bifurcation of common carotid at level of upper border of thyroid cartilage
Ascends to base of skull where it enters through foramen lacerum to lie in carotid canal
Pierces dura forming cavernous sinus to enter cranial cavity
Divides into anterior and middle cerebral arteries at medial end of lateral sulcus
Anterior Cerebral Artery supplies…
Corpus callosum and medial aspects of the hemispheres
Middle Cerebral Artery supplies…
Majority of lateral surface of hemisphere and deep structures of anterior part of cerebral hemispheres
What connects the 2 anterior cerebral arteries?
Anterior Communicating Artery
What connects the internal carotid and posterior cerebral artery?
Posterior Communicating Artery
Where do the vertebral arteries enter the skull?
They then converge where?
To form what?
FORAMEN MAGNUM
Unite at midline at lower border of pons to form BASILAR ARTERY
Where does the Basilar Artery lie?
Anterior Median Fissure
Internal vs External Cerebral Veins
Internal - Run within the substance of brain tissue and end when they reach brain surface where they become external cerebral veins
External - Run on brain surface crossing subarachnoid space to drain into dural venous sinuses
Sinuses in the brain connect ____ to ____
Major cerebral veins to internal jugular veins
Where are the inferior and superior sagittal sinuses found?
The inferior and superior edges of the falx cerebri
Where is the straight sinus found?
Midline of tentorium cerebelli
Where is the transverse sinus found?
Posterior fixed margin of tentorium cerebelli
Where is the sigmoid sinus found?
Deep groove in mastoid part of temporal bone
Where is cavernous sinus found?
Beside body of sphenoid bone
Where is superior petrosal sinus found?
In attached lateral margin of tentorium cerebelli
Where is inferior petrosal sinus found?
Groove between petrous temporal bone and basal part of occipital bone
Emissary veins
Connect veins outside skull and intracranial venous sinuses to inside the cranial cavity (route for infection to spread into cranial cavity)
Largest aggregation of choroid plexus found…
In the choroid plexus
Through what does CSF pass through to go from lateral ventricles to IIIrd ventricle
Interventricular Foramen (of Munroe)
What does CSF pass through to go from IIIrd to IVth ventricle?
Cerebral aqueduct
IVth ventricle communicates with subarachnoid space via…
(CSF can then occupy subarachnoid space around brain and spinal cord)
-Median Foramen of Magendie
-Lateral Foramen of Luschka
Choroid plexus
Invaginations of vessels in ventricles producing a vascular fold of pia mater covered by an epithelium derived form ependymal lining of ventricle
CSF-Brain Barrier
Tight junctions between extracellular space of choroid plexus and inside ventricle except via the choroidal cells (enables control over CSF volume)
Resorption of CSF into venous drainage of brain occurs via tufts of arachnoid mater (arachnoid villi)
Villi calcify with age forming arachnoid granulations
Path of superior oblique
Originates in posterior of orbit, runs forward to pass through trochlear and inserts on posterior part of eyeball (in medial aspect of orbit)
Path of medial rectus
Runs along length of medial orbit deep to SO muscle
Muscles oculomotor (CN III) supplies
Medial Rectus
Superior Rectus
Inferior Rectus
Inferior Oblique
Muscles abducens nerve (CN VI) supplies
Lateral rectus
Lacrimal punti
Small medial holes in upper and lower eyelids
Nasolacrimal duct
Drains from inferior part of lacrimal sac to nasal cavity
Parasympathetic outflow from CNS via…
Oculomotor (CN III), facial (CN II), glossopharyngeal (CN IX), and vagus (CN X)
and S2-4
CN III and VII have branches to the orbit
Where do parasympathetic fibres in oculomotor nerve (CN III) originate?
Edinger-Westphal nucleus in mid brain and travel into the branch to the IO muscle but leave nerve to IO and enter the ciliary ganglion (fibres innervate ciliary muscle and sphincter pupillae)
Path of parasympathetic fibres in facial nerve (CN VII)
Leave facial nerve nerve in middle ear to synapse in a ganglion in the pterygopalatine fossa and supply lacrimal gland
Sympathetic outflow from CNS to orbit via…
T1-L2 (fibres pass into sympathetic trunks)
Fibres arise from T1 and pass up sympathetic trunk through the stellate ganglion to base of skull
Fibres leave superior cervical ganglion of sympathetic trunk to supply dilator pupillae muscle and blood vessels
Which muscles are supplied by the trochlear nerve (CN IV)?
Superior Oblique
SO muscle moves the eye…
Downward and outward
IO muscle moves the eye…
Upward and outward
What is the greater petrosal nerve a branch of?
Parasympathetic branch of facial nerve (CN VII)
Emerges from petrous temporal bone
Bone attachments to tympanic membrane
Malleus attaches to it and it articulates with incus
What is chorda tympani nerve a branch of?
Facial nerve (CN VII) and crosses tympanic membrane
Internal acoustic meatus
Lies in temporal bone existing between inner ear and posterior cranial fossa
Includes vestibulocochlear nerve (CN VIII) and facial nerve (CN VII)
Bulbopontine Sulcus (in pons)
Transverse groove at caudal border of pons
Basilar Sulcus (in pons)
Shallow sulcus in which the basilar artery runs
Middle cerebellar penduncles
Lateral extensions of neural tissue from pons to cerebellum
Anterior medulla fissure
Partial division of medulla in midline
Pyramid of medulla
Elongated eminence (swelling) marking position of corticospinal (pyramidal) tracts
Decussation of the pyramids (medulla)
Diagonally orientated fibre bundles crossing fissure via which 80% of corticospinal fibres cross midline entering opposite lateral white column of spinal cord
Olive
Eminence in medulla caused by underlying inferior olivary nucleus and is concerned with control of movement
Inferior Cerebellar peduncles
Forms posterolateral margin of medulla
Thick bundle of white matter passing into cerebellum
Superior Cerebellar peduncles
Attach midbrain to cerebellum
Tectum
Part of midbrain dorsal to aqueduct
Made up of colliculi
Tegmentum
Part of midbrain ventral to aqueduct
Made up of nerve fibres entering and leaving cerebral hemispheres
Superior Colliculi
Part of visual system (concerned with visual reflexes)
Inferior Colliculi
Part of auditory system (concerned with reflex looking towards a loud noise)
Pineal Gland
Endocrine gland that synthesises melatonin which modulates sleep patterns in both circadian and seasonal cycles
2 nerve pathways in midbrain lying just deep to surface
Inferior Brachium
Superior Brachium
Inferior Brachium
Conveys auditory info from medial geniculate body (nucleus) to inferior colliculi
Superior Brachium
Conveys visual info from lateral geniculate body (nucleus) to superior colliculi
What marks midline of posterior medulla?
Posterior Median Sulcus
The Gracile tubercle of the medulla is…
And it overlies the…
Round swelling either side of midline overlying the GRACILE FASCICULUS
Role of Gracile Fasciculus
Carries fine touch, vibration, proprioception from lower limb
The Cuneate tubercle of the medulla is…
And it overlies the…
A swelling lateral to the gracile tubercles overlying the CUNEATE FASCICULUS
Cuneate Fasciculus role
Fine touch, vibration, proprioception from upper limb
Tegmentum contains nuclei of…
Glossopharyngeal (CN IX)
Vagus (CN X)
Accessory (CN XI)
Hypoglossal (CN XII)
Cranial Nerve Sensory, Motor, or Both mnemonic
I) Some
II) Say
III) Marry
IV) Money
V) But
VI) My
VII) Brother
VIII) Says
IX) Big
X) Brains
XI) Matter
XII) More
What makes up PNS?
12 pairs of cranial nerves
31 pairs of spinal nerves
Cranial nerves I, II, III
I) Olfactory
II) Optic
III) Oculomotor
Cranial nerves IV, V, VI
IV) Trochlear
V) Trigeminal
VI) Abducens
Cranial nerves VII, VIII, IX
VII) Facial
VIII) Vestibulcochlear
IX) Glossopharyngeal
Cranial nerves X, XI, XII
X) Vagus
XI) Accessory
XII) Hypoglossal
Cranial nerves carrying parasympathetic fibres
III) Oculomotor
VII) Facial
IX) Glossopharyngeal
X) Vagus
Make up of cranial nerves with both sensory and motor fibres?
Input from sensory fibres travels to a different nucleus than input from motor fibres
CN V?
Trigeminal
V1) Opthalmic (superior orbital fissure, innervates general sensation to upper face)
V2) Maxillary (Foramen Rotundum, innervates midface)
V3) Mandibular (Foramen Ovale, innervates lower face and motor fibres to muscles in mastication)
Bulbopontine sulcus
Groove between pons and medulla
Fibre types of CN VII (Facial)
Sensory - taste anterior 2/3 tongue
Motor - muscles of facial expression
Parasympathetic - lacrimal gland, submandibular and sublingual salivary glands
The terminal part of the facial nerve divides into 5 branches where?
In the parotid - 5 branches spread out across face providing motor function
The 2 roots of facial nerve
Medial root - motor fibres
Lateral root - sensory and parasympathetic fibres
Which cranial nerves are tested in the gag reflex?
Light touch on back of pharynx
Afferent fibres = CN IX
Efferent fibres = CN X
Look for reflex contraction of palate
Other tests of vagus nerve
Listening to patient’s voice:
Hoarseness = vocal cord paralysis
Nasal sound = soft palate paralysis
Ask patient to say “ah” looking for elevation of palate
Unilateral X lesion = palate and uvula deviate away form side of lesion (towards normal side)
Testing CN XI
Test SCM - patient turns their head against resistance
Test trapezius - look for symmetry when shrugging shoulders
Testing CN XII
Stick tongue out and should go straight forward
XIIth nerve lesion = ipsilateral muscles are paralysed
So contralateral muscles contract pushing tongue to side of lesion
Olfactory nerve
Attached to brain, not brainstem
Function: smell
Receptors: nasal cavity
Axons travel through cribriform plate -> olfactory bulb -> tracts -> temporal lobe
Optic nerve
Attached to brain not brainstem
Function: vision
Fibres travel from retina to primary visual cortex
Role and path of CN III, IV, VI
All motor (extraocular muscles)
Pash through superior orbital fissure
What does oculomotor innervate? What fibres does it carry?
Where are it’s nuclei?
Where do nerves exit brainstem?
MR, SR, IR, IO, LPS
Carries parasympathetic fibres into the orbit to constrict pupil
Midbrain
Nerves exit between pons and medulla
What does trochlear innervate?
Where are it’s nuclei?
SO
Midbrain
What does abducens innervate?
Where are its nuclei?
LR
Pons
What joins the 2 cerebral hemispheres?
Median Vermis
Ridges of cerebral cortex are called…
Folia which are delineated by closely set curving, transverse fissures
3 layers of cerebral cortex
Outer layer - grey matter
Cortex
Inner layer - white matter core (surrounds the Deep Nuclei)
Path of cerebral aqueduct
Runs through midbrain connecting IIIrd and IVth ventricles
Red nucleus
Circular mass of grey matter ventro-lateral to cerebral aqueduct
Substantia Nigra
Black band of nerve cells overlying crus cerebri ventro-lateral to red nucleus both sides
What marks the division between anterior and posterior lobes of each cerebellar hemisphere?
Primary Fissure
Horizontal Fissure of each cerebellar hemisphere marks…
Lateral and posterior margins of hemisphere
What is the anterior lobe of each cerebellar hemisphere bordered by posteriorly?
Primary Fissure
What is the anterior lobe of each cerebella hemisphere bordered by anteriorly?
Primary Fissure
What are the tonsils of the cerebellum?
A prominent rounded swelling of cerebellar cortex either side of vermis
Seen from inferior surface
Flocculus of cerebellum
Approximately ovoid shape lying immediately posterior to lateral foramen of IVth ventricle on each side partly covered by choroid plexus
Lies immediately caudal to entry point of CN VIII
Nodule of cerebellum
Continuous with flocculus via peduncle of white matter
Flocculo-nodular lobe of cerebellum
Flocculus and nodule together, primarily concerned with vestibular info
Tract found in middle cerebellar peduncles
Corticopontocerebellar - info from primary motor cortex of motor plan - same info goes to spine
Tract found in inferior cerebellar peduncles
Vestibulocerebellar tract - vestibular impulses from labyrinths, directly and via the vestibular nucleus
Spinocerebellar tracts
Sensory input for balance and position sense
Ventral spinocerebellar - superior cerebellar peduncles
Dorsal spinocerebellar - inferior cerebellar peduncles
Dentate nucleus
Largest, most lateral of the deep cerebellar nuclei
Zig-zag edged oval mass
Its major fibre bundles passing into superior cerebellar peduncle
Rhomboid fossa
Diamond shaped floor of IVth ventricle limited laterally by the cerebellar peduncles and posteriorly by cuneate and gracile tubercles
Gracile Tubercles
Medial dorsal columns carrying touch, vibration, two-point discrimination and proprioception from the lower limb
Cuneate Tubercles
Lateral dorsal columns carrying touch, vibration, two-point discrimination and proprioception from upper limb
Facial Colliculus
Rounded swelling caused by fibres of facial nerve in substance of pons curving around the nucleus of abducens nerve
Locus Coeruleus
Bluish-grey pigmented noradrenergic cells under ependyma at rostral half of the sulcus limitans
What are the Hypoglossal, Vagal and Vestibular Trigones?
Triangular areas overlying the nucleus of the CN in its name
Obex
Inferior apex of rhomboid fossa
Area Postrema
Small tongue-shaped area immediately rostro-lateral to obex
Associated with nausea control - chemoreceptive trigger zone for emetic response
Septum Pellucidum
Thin, triangular, vertical, double membrane separating anterior horns of L and R lateral ventricles running as a sheet from corpus callosum down to fornix
What separates the 2 halves of diencephalon?
IIIrd Ventricle
Interventricular Foramen
Permits CSF flow from lateral to IIIrd ventricle
Cerebral Aqueduct
Connection between IIIrd and IVth ventricle (travels through brainstem)
Paracentral Lobule
U-shaped gyrus containing respresentations of lower limb within the primary motor and somatic sensory areas of the cortex
Cingulate sulcus is situated…
Just above cingulate gyrus separating it from the rest of the hemisphere
What is the Striae of Genari?
White band in primary visual cortex running parallel with pial surface in mid-depth of grey matter
This feature gives the name Striate Cortex to the primary visual area
Primary Motor Cortex position
Anteriorly - aka pre-central gyrus (grey matter over twice as thick as that of the sensory)
Primary Somatosensory Cortex position
Posteriorly - aka post-central gyrus (thinner grey matter than motor)
Corpus Callosum connects…
2 halves of brain (broad arched band of white matter)
Fornix
Bundle of white matter beneath corpus callosum connecting hippocampus with diencephalon and precommissural septum
Commissure of the Fornix
Fibres from one hippocampus cross to opposite fornix and so back to opposite hippocampus
Fornix connects to mammillary bodies via…
Columns of the fornix
Anterior commissure
Thick white matter bundle interconnecting temporal lobes and olfactory structures of each side
Lamina Terminalis
Thin sheet of ependyma and pia extending downwards from rostrum of callosum and fornix to anterior wall of IIIrd ventricle
Interthalmic adhesion
Flattened grey disc joining the thalami of each side behind the interventricular foramen
Medial Geniculate Nucleus
Relays auditory info from midbrain to auditory cortex passing some fibres, via the inferior brachium, to the inferior colliculi
Lateral Geniculate Nucleus
Relays visual info from optic nerve to both visual cortex (via optic radiation for vision) and the superior colliculi (via the superior brachium for pupillary reflexes)
Ventral and Dorsal parts of diencephalon
Ventral - Hypothalamus
Dorsal - Thalamus
Association Fibres
Link cortical regions within 1 cerebral hemisphere
Commissural Fibres
Link similar functional areas of the 2 hemispheres
Projection fibres
Link cortex with subcortical regions (thalamus, spinal cord, etc)
2 basic functions of uniting the 2 cerebral hemispheres
1) Bringing together separate representations of the 2 halves of the body, the visual field and auditory surround
2) Uniting areas of cortex which have functions specialised to 1 hemisphere
Foramen Magendie
Links IVth ventricle and cisterna magna
Role of limbic system
Acts as an interface between internal and external environment
Role in learning
Role in regulation and translation of our emotional state into appropriate behaviour
Main parts of limbic system connected via…
The Papez Circuit
List the structures of the limbic system
Cingulate gyrus
Hippocampal formation
Parahippocampal gyrus
Anterior perforated substance
Septal nuclei
Uncus
Amygdala
Cingulate gyrus lies…
Just above corpus callosum
What lobe is the parahippocampal gyrus part of?
Temporal lobe
Uncus
Hook-shaped region of cortex
Anterior end of temporal lobe
Role in olfaction, emotions, memory
Choroid Fissure
C-shaped site of attachment of choroid plexus in the lateral ventricles (runs between fornix and thalamus)
Stria Terminalis
Slender bundle of white fibres accompanying curve of caudate around into temporal horn of ventricle
Connects amygdala to septum and hypothalamus
Fimbria
Efferent fibres from hippocampus heading to fornix forming flattened, longitudinal white matter bundle
Posterior Horn of Lateral Ventricle
Variable extension of lateral ventricle into occipital lobe
Pes Hippocampi
2-3 elevations in lower anterior surface of hippocampus (paw-like appearance)
Claustrum
Part of basal ganglia (as it’s a subcortical nucleus derived from the telencephalon)
Receives from and projects to cerebral cortex
What separates claustrum from putamen?
Extreme capsule (white matter)
What separates putamen and lateral segment of globus pallidus?
Lateral medullary lamina (white matter)
What separates lateral and medial segments of globus pallidus?
Medial medullary lamina (white matter)
What type of matter is the globus pallidus?
Grey Matter
Forceps Major (contains fibres from callosum) connects…
Parietal to parietal and occipital to occipital lobes
Forceps Minor (contains fibres from callosum) connects…
Frontal lobes
Cisterna Magna
Subarachnoid space below the inferior surface of the cerebellum, behind the medulla
Vertebral column layout
Cervical - 7 vertebrae
Thoracic - 12 vertebrae
Lumbar - 5 vertebrae
Sacrum - 5 fused vertebrae
Coccyx - 4 or more fused rudimentary vertebrae
What is the uppermost palpable spinous process?
7th cervical vertebra (the vertebra prominent)
Highest point of iliac crest is in line with what part of the spine?
Interval between L3 and L4
Facets of spinous processes role
Guide and constrain motion of vertebrae
Change in spinal curvature from foetus -> after birth
Foetus - C shaped with concavity facing anteriorly
After birth - anterior convexity in cervical due to looking up, anterior convexity in lumbar due to weight bearing on legs
4 movements in vertebral column
Flexion
Extension
Lateral Flexion
Rotation
Rotation is maximum in thoracic but flexion and extension are limited in thoracic due to rib cage
Role of intervertebral discs
Withstand compression forces whilst being flexible enough to allow movement between vertebrae
Structure of intervertebral disc
Nucleus pulposus surrounded by an annulus fibrosis
Nucleus pulposus of intervertebral disc
Well hydrated gel containing proteoglycan, collagen and cartilage cells
Annulus fibrosis of intervertebral disc
10-12 concentric layers of collagen
Annulus fibrosis attaches to vertebral bodies as well as the posterior longitudinal ligament
Which muscle covers the vertebral column?
Erectus Spinae
What is the epidural space?
Space between vertebrae and dura mater of spinal cord
What is contained within the epidural space?
Small arteries supplying spinal cord and vertebral venus plexuses.
Veins in these plexuses (Batson’s veins) contain no valves and communicate freely with intercostal and pelvic veins
31 spinal nerves come from…
8 cervical nerves (8th emerges below C7 vertebra)
12 thoracic nerves
5 lumbar nerves
5 sacral nerves
1 coccygeal nerve
What does dorsal root of spinal nerve carry?
Sensory fibres
What does ventral root of spinal nerve carry?
Motor fibres
Anterior and posterior roots of a spinal nerve join together at the…
Intervertebral foramen
After the intervertebral foramen spinal nerve divides immediately into…
Anterior and posterior rami containing both sensory and motor fibres
Spinal nerves leave the intervertebral canal through…
The intervertebral foramen
Boundaries of intervertebral foramen
Anteriorly bounded by bodies of adjoining vertebrae and the intervening intervertebral disc
Posteriorly bounded by synovial joints between the 2 superior and 2 inferior articular processes
Cells of origin of dorsal root fibres reside in…
the dorsal root ganglion
Conus medullaris
Tapering end of the spinal cord
Filum Terminale
Fibrous strand extending from conus medullaris to coccyx
Cauda Equina
Nerves from lower part of cord (sacral and lumbar) hanging obliquely downwards
Where would you do a lumbar puncture? Why?
L3/L4 as spinal cord finishes at L1/L2
Below that is Cauda Equina
What is a striatum?
Lentiform nucleus connected to caudate nucleus connected to amygdala
Amygdala role
Emotional response
Papez Circuit
Cingulate Gyrus
Parahippocampal Gyrus
Hippocampus
Fornix
Mammillary body
Thalamus
(back to cingulate gyrus)
Path of lateral corticospinal tract (descending)
Travels from motor area of cortex and decussates in medullary pyramids
Path of lateral spinothalamic tract (ascending)
Cross straight away at anterior nerve roots (before entering medulla)
Geniculate Fibres
Fibres in the region of the genu of the internal capsule; they originate in the motor part of the cerebral cortex
What process creates the pivot joint between C1 (atlas) and C2 (axis)?
Odontoid peg
Pupillary Light Reflex
Afferent limb (input) = CN II
Efferent limb (output) = parasympathetic fibres in CN III
Light shone into 1 eye: Ipsilateral pupil constricts = direct response
Contralateral pupil constricts = consensual response
Motor innervation to face
Part of motor cortex dedicated to upper face, part dedicated to lower face
Cell bodies of UMNs reside in the motor cortex and their axons travel to facial motor nuclei in pons
Axons of UMNs for both upper and lower face cross at the midline synapsing on the contralateral CN VII motor nucleus
Facial motor nucleus also receives input from region of ipsilateral motor cortex responsible for upper face
CN XII
Hypoglossal
Motor nerve - muscles of tongue
Arises from medulla
Leaves through hypoglossal canal
CN XI
Accessory
Cranial part - rootlets arise from medulla leaving via jugular foramen by joining the vagus
Spinal part - ventral horn spinal cord C1-5
Travels up through foramen magnum
Leaves again through jugular foramen
Innervates sternocleidomastoid and trapezius
CN IX
Glossopharyngeal
Sensory, motor, parasympathetic
Taste - posterior 1/3 of tongue
General sensation (touch, temp, pain) to pharynx, eustachian, posterior 1/3 tongue
Parasympathetic to parotid gland
Afferents from carotid sinus (baroreceptors) and carotid body (chemoreceptors)
CN X
Vagus
Sensory, motor, parasympathetic
General sensation - larynx, pharynx, oesophagus, EAM, tympanic membrane
Visceral afferents - thoracic and abdo viscera
Afferents from aortic bodies (chemoreceptors) and aortic arch (baroreceptors)
Motor - soft palate, pharynx, larynx
Parasymp - thoracic and abdo viscera
CN VIII
Vestibulocochlear
Sensory
Vestibular afferents -> vestibular nuclei (connect to spinal cord, cerebellum, nuclei of CN II,IV,VI, cerebral cortex for posture, balance, eye movements, conscious perception of head position)
Cochlear afferents -> cochlear nuclei (primary auditory cortex - conscious perception of sound, auditory association cortex - interpretation)
What is the auditory association area?
Wernicke’s Area
What is the primary auditory cortex?
Superior temporal gyrus
Subarachnoid cisterns
Spaces where arachnoid membrane and pia mater aren’t in close proximity and CSF forms pools/cisterns
