Neuroanatomy Flashcards
What forms the floor of the 4th ventricle?
Rhomboid Fossa
What makes up the dorsal brainstem?
Tectum, rhomboid fossa, gracile and cuneate nuclei and medulla oblongata
What seperates the gracile and cuneate tubercles
posterior median sulcus
What makes up the tectum
the superior and inferior colliculi
What makes up the diencephalon?
hypothalamus, thalamus, epithalamus (dorsal to thalamus) , subthalamus (ventral to thalamus) and the 3rd ventricle
What joins each side of the thalami?
interthalamic adhesion
Where does the anterior nuclear group receive fibres from and project fibres to?
Mammillary bodies (limbic) –> cingulate cortex
Where does the medial nuclear group receive fibres from and project fibres to?
Hypothalamus, amygdala (limbic) –> prefrontal cortex
Where does the ventral anterior nucleus receive fibres from and project fibres to?
Basal ganglia –> premotor cortex
Where does the ventral lateral nucleus receive fibres from and project fibres to?
Globus pallidus, substantia nigra, cerebellum –> primary motor cortex (frontal)
Where does the ventral posterior nucleus (lateral) receive fibres from and project fibres to?
somatic afferent fibres from body –> somatosensory cortex (parietal)
Where does the ventral posterior nucleus (medial) receive fibres from and project fibres to?
somatic afferent fibres from head –> somatosensory cortex (parietal)
Where does the medial geniculate nucleus receive fibres from and project fibres to?
inferior collicus –> auditory cortex (temporal)
Where does the lateral geniculate nucleus receive fibres from and project fibres to?
optic tract and superior collicus –> visual cortex (occipital)
Where does the pulvinar nucleus receive fibres from and project fibres to?
Extensive connections with association cortices of parietal, temporal and occipital lobes.
What does the epithalamus contain?
Habenula (stalk and connected nerve fibres of the pineal gland) and the pineal gland
What is the pineal body?
An endocrine gland synthesising hormones including melatonin. May have an effect on circadian rhythyms.
What is the lentiform nucleus made up of?
putamen and globus pallidus
What is the striatum made up if?
Caudate and Putamen
Where is the primary somatosensory cortex?
Postcentral gyrus on the parietal love
Where is the secondary somatosensory cortex?
Adjacent to the head region of the primary SS cortex
Where does C4 innervate?
Shoulder tip
Where does T4 innervate?
Nipples
Where does T10 innervate?
Belly Button
Where does L1 innervate?
Inguinal ligament
What is the spinothalamic tract responsible for?
Coarse touch, pain, temperature
What is the dorsal column pathway responsible for?
Proprioception, vibration, fine touch
What is the spinocerebellar pathway responsible for?
proprioception
What is Brown-Sequard synfrom
hemisection of spinal cord, ipsilateral loss of vibration, fine touch + contralateral loss of temp, pain and coarse touch.
What is the motor cortex made up of?
Primary motor cortex, paracentral lobule, premotor cortex, supplementary motor area
Describe the cortico-spinal fibres
Pyramidal tract, desc motor pathway from cerebral cortex, fibres run to contralateral ventral and dorsal horns of spinal cord
Describe the cortio-nuclear fibres
Descend with cortico-spinal fibres, terminate in motor nuclei of cranial nerves of pons and medulla
Describe the cortico-pontine fibres
First order fibres in cortico-pontine-cerebellar pathway, terminate ipsilaterally in pontine nuclei
What are medullary pyramids?
Eminences marking position of underlying fibres, 80% fibres decussate here
What are the medullary olives?
Swellings lateral to pyramids on each side, contain inferior olivary nuclei.
What are the inferior olivary nuclei?
Have connection with contralateral cerebellar circuits
Lateral corticospinal tract (in spinal cord)
already decussated and mainly controls distal muscles
Ventral corticospinal tract (in spinal cord)
hasn’t decussated and mainly controls trunk muscles- balance
Rubrospinal tract (in spinal cord)
function in humans unclear- fine finger movement/proximal trunk?
Reticulospinal tract (in spinal cord)
influences muscle tone and responsiveness
Vestibulospinal tract (in spinal cord)
balance
Tectospinal tract (in spinal cord)
reflexes
What are substantia nigra?
Black, dopamine producing, visible superior to cerebral peduncle?
In what condition to substantia nigra die?
Parkinson’s
What are the red nucei?
Imaginary on cadaver, give rise to rubrospinal tract from above.
What can a raised ICP cause?
herniation of cerebellar tonsils –> foramen magnum and brainstem compression
Where foes the floccular lobe lie?
Mediun surface of where 4th ventricle protrudes into base of cerebellum
What does the floccular lobe do?
Concerned with vestibular information
What happens in Huntingdon’s?
atrophy of caudate nucleus, leads to hyperkinetic movement
What happens in Parkinson’s?
inhibits too many movements, hard to initiate movement
What motor fibres synapse at the genu?
V, VII, IX, X, XI, XII
What can cause cerebellar dysfunction?
alcohol, ischaemia/stroke, thiamin deficiency, demyelination
What signs are there of cerebellar dysfunction?
Dysdiadokinesis Ataxia Nystagmus Intention tremor Slurred speech Hypotonia Past pointing
Olfactory Nerve
Special sensory
Olfaction. No brainstem nuceli.
Direct projection to reach limbic and olfactory cortex structures, passes through cribiform plate.
Optic Nerve
Special sensory
Sight and pupillary reflex. Originates in thalamus, passes through optic canal. Retina–> LGN.
Oculomotor Nerve
Motor Eye movement (not lateral) and levator paplebrae. Edinger-Westphal nucleus. Roots emerge from medial surface of each crus cerebi into the interpenduncular fossa --> cavernous sinus --> superior orbital fissure
Trochlear Nerve
Motor
Eye movement- superior oblique. Emegres dorsally and curves around lateral peduncle –> interpeduncular fossa. `Through cavernous sinus to superior orbital fissure.
Trigeminal Nerve
Both
Sensation of touch on face, mastication, taste. Emerges through middle cerebellar peduncle lateral to pons. Goes through superior orbital fissure (V1), foramen rotundum (V2) and foramen ovale (V3)
Abducens Nerve
Motor
Eye movement- lateral oblique. Emerges either side of the midline and passes rostrally over the ventral pontine surface. Exits through superior orbital fissure. Long intracranial course and may be stretched with abnormalities (including raised ICP)
Facial Nerve
Both
Muscles of facial expression, salivation, tear secretion. Emerges medially at lateral margin of medullary-pontine angle. Leaves through internal auditory meatus –> stylomastoid foramen
Vestibulocochlear Nerve
Sensory
Hearing and balance. Emerges laterally at margin of medullary-pontine angle. Leaves through auditory meatus.
Glossopharyngeal Nerve
Both
Taste, salivation and swallowing. Slender rootlets found in venterolateral sulcus at posterolateral margin of the olive of the medulla- lying across cerebellar flocculus. Exits skull through jugular foramen.
Vagal Nerve
Both
Gastric and pancreatic secretions. GI movement, cardiac reflex, visceral reflect, resp. reflex, speech. Slender rootlets found in venterolateral sulcus at posterolateral margin of the olive of the medulla- lying across cerebellar flocculus. Exits skull through jugular foramen.
Accessory Nerve
Motor
Muscle movement of trapezii and SCM. Spinal and cranial parts. Slender rootlets found in venterolateral sulcus at posterolateral margin of the olive of the medulla- lying across cerebellar flocculus. Exits skull through jugular foramen.
Hypoglossal Nerve
Motor
Tongue movement. Formed by series of fine nerve rootlets from ventrlateral sulcus. Goes through hypoglossal canal
What are caruncle
red corners of the eye
What the lacrimal punctum
collect tears from lacrimal glands
What surrounds the eyeball?
Fascial sheath, supported by lateral and medial check ligaments, suspensory ligaments and retrobulbar fat
Pathway of vision
Retina –> optic nerve –> LGN of thalamus
What happens at the optic chiasm?
Optic nerve partially crosses. Fibres from nasal half decussate and join uncrossed fibres from temporal/lateral half from other side
Where do the fibres split and go?
Before LGN, lateral root goes to LGN and medial root goes to superior colliculus of the tectum of the midbrain. Visual reflexes facilitated here.
What is input from the frontal eye field necessary for?
Voluntary eye movements
Where is the coordination of eye movements organised?
Specialised regions of the reticular formation
Where is the visual cortex?
Primary visual cortex (area 17) occupies walls of posterior part of calcarine sulcus.
What does retinotopic projection of the cortex cause?
Central vision to be projected more posteriorly and peripheral vision more anteriorly.
What protects against loud sounds?
Tensor tympani and stapedius
What is the innervation of tensor tympani
CNIII, V3 (mandibular)
What is the innervation of stapedius
CNVIII (facial)
What is the function of the pharyngotympanic/ eustachian tube?
Ventilates middle ear space, maintaining pressure.
Where does the auditory pathway go?
Synapses in dorsal and ventral cochlear nuclei, continues in lateral lemniscus to inferior collicus–> medial geniculate body by ‘branchium of inferior collicus’. From MGN in thalamus –> auditory cortex of temporal lobe via auditory radiation of the internal capsule.
Where is the primary auditory cortex found?
Approx. area 41, occupies part of floor and lower lip of lateral fissure opposite lower end of post central sulcus. Surrounded by association cortical areas.
What is Wernicke’s area?
Speech area- part of temporal love. Perception and understanding.
What would lesions on Wernicke’s area lead to?
Receptive aphasia
What is Broca’s area?
Speech area- part of frontal lobe. Motor side of speech.
What would lesions on Broca’s area lead to?
Expressive aphasia
What is the superior speech cortex?
Corresponds to the SMA, damage is not devastating to speech.
What is a Berry Anurism Rupture
Subarachnoid so blood enters CSF –> ‘thunderclap headache’
CN III and VI likely to be affected
Associated with polycystic kidney and connective tissue diseases/disorders
Ischaemic Stroke
RFs: smoking, hypertension, high cholesterol/atherosclerosis, alcohol, AF, clotting disorders, vascular disease
150,000/ year + undiagnosed and TIAs
Lesion in left hemisphere would present contralaterally
Axillary nerve injury
Shoulder
Deltoid and teres minor paralysis, no abduction of arm and loss of upper lateral sensation
Radial nerve injury
Humerus (radial groove with fracture) and axilla
Dependent of location of lesion- loss of surface of lateral 3 fingers –> loss of posterior compartment
Musculocutaneous nerve injury
Uncommon- stab wound to axilla
Weak shoulder flexion, weak elbow flexion, weak supination. Loss of sensation to lateral forearm
Median nerve injury
Wrist (also elbow)
Poor wrist flexion, weak elbow flexion, weak supination, lateral forearm sensation loss
Ulnar nerve injury
Elbow (also wrist)
Loss of thumb flexion, paralysis of flexors and pronators of forearm, loss of sensation
Where does the brachial plexus arise from?
C5-T1
Where does the lumbar plexus arise from?
T12-L4
Where does the sacral plexus arise from?
L1-S4
Femoral nerve injury
Trauma/surgery
Weakness/numbness in innervating region (hip flexion/knee extension). Difficulty going up and down stairs ‘knee bucking’
Obturator nerve injury
Pelvic trauma/surgery
Pain, numbness and weakness
Sciatic nerve injury
Sciatica (spinal disk herniation, spinal stenosis etc
Shooting, descending posterior leg pain
Common peroneal injury
Lateral knee trauma (‘car bumper’)
Foot drop- affecting the lateral and anterior compartments of the lef
Tibial nerve injury
Posterior knee
Inability to curl toes, weakness of foot muscles, loss of sensation in sole of foot
Upper brachial plexus injury
Erb’s Palsy
‘waiter’s tip’ - C5-C6 paralysis of biceps and other, can’t abduct shoulder, laterally rotate, supinate or shoulder flex easily. Also loss of lateral sensation, occurs from over-stretching the neck/shoulder angle (fall on side of head and bend)
Lower brachial plexus injury
Klumpke palsy
‘claw hand’- T1- ulnar and median nerve. Loss of small muscle movements in hand. Injury occurs from rupping the arm upwards e.g grabbing a branch when falling out a tree.
Subdural haemorrhage
venous blood, rupture of bridging veins
common mechanism: head trauma causing shearing forces. Elderly most at risk (more falls and weaker tissues) also can be sign of abuse ‘shaken baby syndrome’
Extradural haematoma
Between skull and periosteum, only detaches between suture lines. From depressed skull fracture most often. Eg middle meningeal artery rupture at pterion.
‘Lucid interval’ where person this fines after initial unconscious, then rapid deterioration.
10-15% mortality, 2% head injuries but 5-15% deaths
Upper motor neuron injuries
Stroke Intracranial bleed Cerebal Palsy MS Traumatic Brain Injur
Lower motor neuron injuries
MND (can be both)
Specific nerve palsies
Peripheral neuropathy
Poliomyelitis
Femoral nerve block
LA to femoral nerve supplying periosteum of femur. Performed following fractured head of femur.
Neurological examination
Inspection Tone Power Reflexes Sensation Coordination
Where do association fibres run?
Entirely within one hemisphere, 3 major association fibres per hemisphere
Superior longitudinal fasiculus
association fibre: connect frontal, parietal and occipital loves
Cingulum
association fibre: inside the cingulate gyrus, connecting distant regions of the cortex
Inferior longitudinal fasiculus
association fibre: connect temporal and occipital loves
Small association fibre bundles
External capsule- between claustrum and putamen
Extreme capsule- between claustrum and insular cortex
U fibres- join adjacent sections of cortex
What are the functions of commissural fibres?
Uniting sensory information of cerebral hemisphere.
Unite areas of cortex that has specialised functions to one hemisphere
Corpus Callosum
Largest commissural fibre, fibres curve forward and backwards into different lobe.
Has posterior gibres, anterior fibres and horizontal fibres
Posterior fibres of corpus callosum
pass more laterally than anterior fibres because of deep parieto-occipito sulcus (forceps major –> occipital love)
Anterior fibres of corpus callosum
forceps minor (genu–> frontal lobe)
Horizontal fibres of corpus callosum
form rood of lateral ventricle and laterally interdigitate with vertical corona radiata (projection fibres) - carry info subcortical–> cortical regions
Anterior commissure
(thick) crosses midline horizontally between lamina terminalis. Connect the temporal lobes
Posterior commissue
(thin) crosses midline at junction of midbrain and diencephalon, anterior to superior collicus and posterior to pineal body
Hippocampal commisure
(commissure of fornix) a thin layer inferior to the splenium of the corpus callosum- formed by fibres that originate in the hippocampal formations and cross the midline
Internal Capsule
large compact bundles of projection fibres of the hemispheres
What makes up the limbic system?
Hippocampus, cingulate gyrus, cingulum and fornix, hypothalamus, amygdala
What is the limbic system?
Part of the brain involved with learning, memory and emotion.
What diseases affect the limbic system?
Schizophrenia, Alzheimer’s disease and some forms of epilepsy.
Where is the hippocampus?
Rounded elevation, approx. 5cm long on the floor of the inferior horn of the lateral ventricle, expands anteriorly
Structure of the hippocampus?
Ventricular surface is covered with ependyma beneath which the alveus (white myelinated fibre) pass around ventricle to become the fornix
Where is the cingulate gyrus found?
Lies immediately dorsal and parallel to the corpus callosum.
Anteriorly- turns below rostrum of callosum
Posteriorly- continues downwards, forwards and laterally onto infero-medial surface of temporal lbe
What is the uncus?
Hook shaped region of cortex at anterior end of cingulate gyrus, provides surface marking for underlying amygdala and parahippocampal gyrus.
What is the cingulum?
bundle of axons passing round deep to cingulate and hippocampal gyri
What is the entohinal cortex?
interface between hippocampus and the neocortex
What is the fornix?
Bundles of white matter attached inferiorly to septum pellucidum on each sde.
Where does the fornix fuse?
Fuse anteriorly in the midline and turn vertically down to project posteriorly behind the anterior commissue and reach the mammilary bodies
What do the mamillary bodies contain?
Mammillary nuclei of the hypothalamus
What is the function of the mammillary bodies?
Anterior part- sned fibres to anterior nuclei of the thalamus which then project to cortex of cingulate gyrus.
What is the hypothalamus?
Ventral division of the diencephalon- lamina terminalis –> immediately behind mammillary bodies
What is the function of the hypothalamus?
An important centre for homeostasis and autonomic/neuroendocrine control
What splits the diencephalon in half?
The third ventricle- continues into cerebral aqueduct.
Where is he amygdala located?
anterior and slightly superior to the anterior hippocampus?
Where fibres are in the amygdala?
Fibres form the stria terminalis, the lateral ventricle and amygdalofugal pathway in the ventral part of the hemisphere
Where does the amygdala receive input from?
Receives a major, direct unput from the olfactory bulb
What forms the ventral striatum?
Nucleus accumbens septi (part of septal nuclei) and region of anterior perforated substance (olfactory tubercle)
Where does the striatum receive projections from?
Intralaminar and midline nuclei of thalamus and dopaminergic fibres from ventral tegmental area (adjacent to substantia nigra)
Where does the striatum project fibres to?
Ventral extension of globus pallidus, found below anterior commissure, called ventral pallidum, then projects to thalamus
What is CSF produced by?
Choroid plexus, located in the lateral third and fourth ventricles
Where does CSF enter the subarachnoid space?
via the lateral and median apertures in the fourth ventricle
How is CSF reabsorbed?
Via the arachnoid granulations mainly into the superior sagittal sinus.
What does a T1 MRI light up?
Bone
What does a T2 MRI light up?
bone + CSF
What allows CSF to go around spinal cord?
Foramen of Luschka (anterior) and Magnedie (posterior)
communicating hydrocephalus
communicating (too much CSF/not being drained
non-communicating hydrocephalus
blockage eg tumour compression
Hydrocephalus treatment
shunt relieves pressure
lumbar puncture in older patients
DO NOT LP people with raised ICP
What is hydropcephalus
increased volume of CSF in ventricles
Wernicke’s encephalopathy
acute thiamine (vit B1) deficiency (chronic alcohol excess increases susceptibility) - commonly causing ocular palsies, cerebellar cell damange
Korsakoff’s Amnesia/Dementia
chronic phase thiamine (vit B1) deficiency (chronic alcohol excess increases susceptibility) - general cerebral atrophy, damage to mammillary bodies and thalamic nuclei that synapse with limbic system. Causes retro/anterio-grade amnesia, confabulation (invented memories), apathy and blindness
