neuroanatomy Flashcards
4 Midline structures in the brainstem
Motor pathway, medial lemniscus, Medial longitudinal fasciculus, motor nucleus (3,4,6 or 12; if it is a factor of 12 except 1 or 2, it is midline).
4 lateral structures in brainstem
Spinocerebellar pathway, spinothalamic pathway, sensory nucleus of V, (sympathetic pathway too)
Cranial nerve nuclei in medulla
9, 10, 11, 12. Only 12 is midline.
Cranial nerves in pons
5,6,7,8. Only 6 is medial
Cranial nerves above the pons
1, 2, 3 and 4. (3 and 4 are medial in the midbrain.)
Corpus callosum
Fibre bundle linking hemispheres
Anterior cerebral artery
Supplies medial aspects of sensory and motor cortical areas. Blockage causes paralysis and loss of cutaneous/proprioception of lower limb.
Middle cerebral artery
Supplies lateral and inferior cortical hemispheres; sensory cortex, motor cortex, internal capsule and basal ganglia. Blockage leads to paralysis and loss of cutaneous and proprioceptive sensation. Lower limb likely to be spared.
Posterior cerebral artery
Supplies occipital lobe, including V1.
Choroid plexus
Capillary bed enclosed in pia and ependyma. Found in Lateral ventricles, IIIrd and IVth ventricles.
Vertebral arteries
Supply blood to the basilar artery. give off posterior inferior cerebral and spinal arteries.
Cerebral aqueduct
communicates between IIIrd and IVth ventricles
Mesencephalon
Becomes midbrain
Rhombencephalon
Becomes pons and medulla; cerebellum develops on dorsal surface.
Central sulcus
Divides somatosensory and motor cortex
Lateral sulcus
divides temporal from the frontal and parietal cortex
IIIrd ventricle
associated with the thalamus and hypothalamus
Communication between lateral and IIIrd ventricles
Inter-ventricular foramen
Communication between IIIrd and IVth ventricles
via cerebral aqueduct
CSF in spinal cord
in central canal
Blockage of CSF flow leads to…
hydrocephalus.
CSF enters the subarachnoid space from the IVth ventricle via…
the foramen of Magendie and foramina of Luschka
Cisterna magna
Space between medulla and cerebellum.
Lumbar cistern
Tapped into in a lumbar puncture at level L3/4 or 4/5; between level L2 and upper sacral level.
Basilar artery branches
Anterior inferior cerebellar, pontine arteries and superior cerebellar arteries. Also posterior cerebral arteries
Calcarine sulcus
Medial aspect of occipital lobe; V1 found round this.
Primary visual cortex
Brodmann’s area 17
Primary somatosensory cortex
Brodmann’s 1,2 and 3.
Primary motor cortex
Brodmann’s area 4.
Cerebral angiography
Used to identify thrombosis, aneurysms or vascular blockage caused by tumours.
CAT
Computerised axial tomography; used to investigate tumours, haemorrhage and cerebral atrophy.
Nissl stains
Stain nuclei and cell bodies but not dendrites or axons.
Myelin stain
Used to examine white matter
Golgi stain
Picks out random cells; stains v. dark in entirety
Nociceptive afferents terminate
in dorsal horn
Crossing of nociceptive
Via ventral commissure within spinal cord
First proprioceptive/fine touch synapse
Gracile (lower limb) and cuneate (upper limb) nucleus
Spinothalamic pathway
Nociceptive. Enters spinal cord; synapses in dorsal horn. Crosses spinal cord, ascends contralaterally. Sends branches to reticular formation in medulla. Forms spinothalamic tract in pons - ‘spinal lemniscus’. Spinal lemniscus in midbrain. Synapses in thalamus, projects to cortex
Dorsal column - medial lemniscal pathway
Enters spinal cord; ascends ipsilaterally.. Decussates in medulla; sensory decussation. Ascends in medial lemniscus. Synapses in thalamus, before projecting to the somatosensory cortex.
Interomediolateral nucleus
sympathetic preganglionic neurons; axons to sympathetic chain. Thoracic only.
Clarke’s nucleus
proprioceptive relay cells from lower limb; only present in thoracic and upper lumbar. Roughly at medial side of base of dorsal horn.
Dorsolateral column
Descending motor form cortex
Anterolateral column
Ascending pain/temperature
Dorsal horn
local sensory processin
Ventral horn
Motor neurons
Ventral column
motor descending from brainstem.
Spinal nucleus of V
important for pain and temp of head and neck; prominent in medulla
Motor decussation
Decussation of descending motor fibres at border of medulla and spinal cord.
Sensory decussation in medulla
From gracile and cuneate nuclei to medial lemniscus.
Inferior cerebellar peduncle
sensory info to cerebellum
Cerebral peduncles (midbrain)
Fibres descending from cortex to brainstem and spinal cord.
Tectum in midbrain
Superior and inferior colliculi; dorsal to aqueduct
Ventral nuclei of thalamus
somatosensory and motor co-ordination
Internal capsule
Links cortex and thalamus; ascending and descending fibres. Between nuclei of basal ganglia. Contains efferent corticobulbar, corticospinal, corticopontine fibres, and afferent thalamocortical fibres. Damage –> contralateral hemiparesis
Lissauer’s tract
Part of spinal cord; carries short ascending or descending branches of nociception; jelly like appearance, part of substantia gelatinosa.
Spinothalamic tract terminates
Mostly in thalamus. 3rd order neurons ascend in internal capsule.
Some 2nd order neurons also terminate in reticular formation
Medial lemniscus in pons
flattens out to run over pontine nuclei.
Brown-Sequard syndrome
spinal cord hemisection; ; ipsilateral loss of fine touch and proprioception, contralateral loss of pain and temperature.
infarction of anterior cerebellar arteries in medulla
Loss of pain on contralateral body but not proprioception
Unconscious proprioceptive pathways
Project to cerebellum as well as thalamus
Motor corticospinal pathway
Motor cortex (rostral to central sulcus), internal capsule, cerebral peduncles on midbrain, through pons, medullary pyramids, motor decussation at lower medulla for crossed lateral corticospinal tract. Uncrossed descend in the ventral corticospinal tract.
Stroke leads to
Contralateral paralysis and spasticity.
Premotor and supplementary motor areas
Planning of movement
Motor cortex cells
Some giant cells in layer V, few granule cells.
Inferior olives
climbing fibre input to cerebellum
Corticobulbar fibres
Run with corticospinal but destined fo the medulla; innervate motor nuclei of CN V, VII, IX, X and XII.
Bilaterally innervated cranial nerves
V and XII; complete paralysis does not follow stroke as it does for lower facial muscles.
Upper motorneuron damage
initially flaccid, then hyperreflexia, clonus and positive Babinski’s sign.
Lower motorneuron damage
flaccid paralysis, muscular weakness, muscle wasting, areflexia.
Vestibulospinal pathway
Arise from vestibular nuclei; acts on extensor limb muscles and maintains posture. Lateral vestibular nucleus important in balance; sends out lateral vestibulospinal tract.
Reticulospinal pathway
From reticular formation. Important in posture and coordinated body movement.
Rubrospinal tract
From red nucleus. In man inputs are from motor cortex and cerebellar nuclei, and outputs are to inferior olivary nucleus
Cerebellar inputs
Pons (via mossy fibres) and inferior olive (via climbing fibres); input carried by middle cerebellar peduncle.
Cerebellar outputs
Carried from deep nuclei by superior cerebellar peduncle to thalamus (some red nucleus as well).
Flocculus
Vestibular function; sends outputs to vestibular nuclei. Vestibular and facial nerves enter here.
Lumbar puncture + high intracranial pressure –>
Coning, pressure on brainstem and sudden death.
Deep cerebellar nuclei
dentate nucleus, nucleus interpositus, and fastigial nucleus.
Dentate nucleus
Receives inhibitory innervation from cerebellar cortex; looks like inferior olive but is in cerebellum, not medulla.
Ventrolateral nucleus of thalamus
projects to primary motor cortex. Receives from cerebellum.
Ventroanterior nucleus of thalamus
projects to premotor areas. Receives from cerebellum.
Cerebellar cortex cells
Outer molecular layer; parallel fibres contacting purkinje cell dendrites - few cell bodies.
Purkinje cell layer - Purkinje cell bodies.
Granular layer - lots of small granule cells.
Neostriatum
Caudate and putamen and globus pallidus. Nuclei separated by internal capsule.
Sub. nigra divisions
Pars compacta; dopaminergic.
Pars reticulata; non-dopaminergic.
Caudate and putamen input
Cerebral cortex esp prefrontal and sensorimotor, and sub nigra pars compacta
Globus pallidus
iGP projects to ventral and medial thalamus (output pathway). ePG projects to subthalamic nucleus
Degeneration of sub nigra pars compacta
Parkinson’s disease.
Damage to caudate
Huntington’s disease.
deep brain stimulation in parkinson’s
to subthalamic nucleus.
Inferior colliculus sends brachium to…
the medial geniculate nucleus
Path of cochlear nerve cells
Spiral ganglion send axons to the ventral and dorsal cochlear nucleus (either side of the inferior cerebellar peduncle) in the medulla –> superior olivary nucleus in the pons (bilaterally; binaural interaction. Will not be pinned), –> lateral lemniscus (bilaterally), –> inferior colliculus (midbrain), –> Medial geniculate nucleus (thalamus) –> auditory cortex.
Vestibular nuclei
Lateral important in balance, superior projects to thalamus.
Olfactory pathway
First order; olf. bulb. Second order neurons in olf. tract via olf stria to uncus and pyriform cortes and olfactory tubercle under anterior perforated substance.
Site of entry for striate arteries
Anterior perforated substance. Supply internal capsule, susceptible to stroke.
Hypothalamus and reticular formation in olfaction
Generates endocrine and autonomic responses.
Olfactory tubercle pathway
projects onto thalamus, then insula and orbitofrontal cortex for perception
Destination of optic tract
Lateral geniculate nucleus of thalamus
Optic radiation
From thalamus to V1. Damage leads to upper quadrantanopia or scotoma.
Minor projections of optic tract
to pretectal region in midbrain for pupillary light response,
to suprachiasmatic nucleus,
to superior colliculus.
Optic tract damage
Homonymous hemianopia
Optic chiasm damage
Bitemporal hemianopia
Optic nerve damage
Monocular blindness.
Oculogyric nuclei
III, IV and VI
Co-ordination of oculogyric nuclei
By vestibular nuclei and superior colliculus via the MLF
Damage to the MLF
Nystagmus, diplopia and defects in gaze control
Superior colliculus
Reflex centre for overt attention. Also projects to tectospinal tract.
Ventroposterior thalamus
Somatosensory relay. Associated with superior colliculus.
Anterior nucleus of thalamus
projects to cingulate gyrus.
Medial nucleus of thalamus
Cortico-thalamo-cortical relay to prefrontal cortex
Pulvinar nucleus of thalamuse
Cortico-thalamo-cortical relay to temporo-parieto-occipital association cortex
Cortical layers; layer 4
input from thalamus; inner granular layer. Thick in visual cortex.
Cortical layers; layer 5
Output to subcortical structures; inner pyramidal layer. Enlarged in motor cortex.
Cortical layers; layer 6
feedback to thalamus; multiform layer
Cortical layers; layer 2 and 3
Project to other areas of cortex. Outer granular and outer pyramidal layers.
Cortical layers; layer 1
Mostly fibres; molecular layer.
Cingulate gyrus becomes…
Parahippocampal gyrus
Cholinergic system
Learning and memory; associated with Alzheimers.
Noradrenergic system
Attention. From locus coeruleus.
Serotoninergic system
Emotional behaviour and OCD.
Orbitofrontal cortex.
Above eyes. Emotional and social behaviour. Input from and output to cortex, hippocampus, amygdala and hypothalamus.
Nucleus accumbens
emotional and motivational behaviours; implicated in schizophrenia.
Entorrhinal cortex projects to
Dentate gyrus of hippocampus and CA3.
Dentate gyrus of hippocampus
projects via mossy fibres to CA3
CA3 projects…
via Schaffer collaterals to CA1.
CA1 projects to
Subiculum, and both project to hypothalamus via fimbria/fornix
Amygdala position
Deep to uncus; above hippocampus.
Damage to amygdala
Herpes Simplex and Urbach-Wiethe’s disease.
Input to hippocampus
From entorrhinal cortex/parahippocampal gyrus. Mostly this is from sensory association areas.
Output from hippocampus
fimbria-fornix to hypothalamus, mammillary bodies and nucleus accumbens.
Also back to entorrhinal cortex.
Inputs to cingulate gyrus
Neocortex and thalamus
Outputs of cingulate gyrus
Mostly to parahippocampal gyrus.
Parts of parahippocampal gyrus
pyriform cortex (olfaction) and entorrhinal cortex (recognition).
