Neuroanatomy January Flashcards
What is NG2?
Neural-glial antigen 2 expressed on oligodendrocyte progenitor cells, also called NG2 cells. These are highly branched, highly distributed, can become oligodendrocytes, and are involved in physiology and repair.
How many dorsal arteries are there?
2
How many ventral arteries are there?
1 large
What types of cells are found around the central canal?
Stem cells
What is a bundle of fibres called in CNS and in PNS?
CNS - tract
PNS - nerve
What is a collection of neuron cell bodies called in CNS and PNS?
CNS - nucleus
PNS - ganglion
Does the amacrine cell in the retina have an axon?
No
Do sensory neurons have axons and dendrites?
They do not have dendrites and have no synapses on cell body
What are satellite cells?
Glia found around neuron bodies in ganglia
What is a Remak cell?
Schwann cells which do not myelinate, but rather surround unmyelinated peripheral nerve fibers
What occurs in MS?
loss of oligodendrocyte myelination in CNS
What is contained within subarachnoid space?
CSF
Is there a subdural space?
No unless bleeding occurs there
In which week of human development does primary neurulation occur?
4th week
Closure occurs first, near hind brain - spinal cord boundary. progresses in anterior and posterior directions, closing caudal neuropore last of all.
Where is CSF made and transported?
Largely made by choroid plexuses in lateral ventricles, passes to third ventricle via interventricular foramina.
Does myelination occur before or after birth?
Both.
Many tracts eg corticospinal tracts myelinated after birth.
What is the diencephalon?
region of the embryonic vertebrate neural tube that gives rise to anterior forebrain structures including the thalamus, hypothalamus, posterior portion of the pituitary gland, and pineal gland.
What is another name for the Sylvian fissure?
Lateral fissure
What are the arachnoid villi?
Granulations which act as one way valves for flow of CSF into venous blood, stimulated by hydrostatic pressure.
What is a cause of hydrocephalus?
blockage of cerebral aqueduct -> swelling of ventricles, squashing brain
What are the names of enlargements in spinal cord near to limbs?
cervical enlargement, for upper limb
lumbosacral enlargement, for lower limb
Which dermatome is at the belly button/umbilicus?
T10
What is the grey matter of spinal cord divided into?
Rexed laminae
Which lamina is named substantia gelatinosa?
II
this is larger, full of small unmyelinated neurons
Which laminae are the superficial dorsal horn laminae?
I and II
related to pain
Where are motor neuron cell bodies found?
Ventral horn lamina IX
What are intrafusal muscle fibres responsible for?
Resetting muscle spindle so it can continue to detect stretch
What is poliomyelitis?
Virus that causes flaccid paralysis
Where are primary afferent cell bodies found?
DRG
Are primary afferents excitatory or inhibitory?
Excitatory
What is the Babinski sign?
reflex when instrument run down lateral sole of foot causes big toe extension.
in normal adults the big toe points down. with upper motor neuron lesion, big toe points up.
in babies big toe also points up because corticospinal tracts not yet myelinated.
What is the role of cerebellar peduncles?
Connect cerebellum with CNS.
How many cerebellar peduncles are there?
6; 3 on each side. They are found on each side of the midline. Superior peduncle --> midbrain Middle --> pons Inferior --> medulla
What are the colliculi?
Small swellings in midbrain roof involved in vision, hearing. Part of the tectum.
Superior colliculi - eye movements.
Inferior colliculi - relay station in auditory pathway
What is the name of grey matter surrounding cerebral aqueduct?
Periaqueductal grey.
primary control center for descending pain modulation.
What is the crus cerebri?
Cerebral peduncle. Part of the midbrain that links the remainder of the brainstem to the thalami and thereby, the cerebrum. They are the most anterior structure in the midbrain and contain the large ascending and descending tracts that run to and from the cerebrum.
Where is the 4th ventricle?
The fourth ventricle extends from the cerebral aqueduct (aqueduct of Sylvius) to the obex, and is filled with cerebrospinal fluid (CSF). The fourth ventricle has a characteristic diamond shape in cross-sections of the human brain. It is located within the pons or in the upper part of the medulla
Which artery supplies the pons?
Basilar artery, at front of pons.
The basilar artery carries oxygenated blood to the cerebellum, brainstem, and occipital lobes.
If a branch of basilar artery supplying corticospinal tracts is blocked it causes locked-in syndrome.
What are the divisions of the medulla?
Open or closed (lower part).
Depends on whether CSF-containing cavities are surrounded by the medulla (closed medulla) or not (open medulla). The medulla becomes open when the central canal opens into the fourth ventricle.
Which laminae are in the dorsal horn?
Laminae I-VI
What information does the spinothalamic tract carry?
Pain, temperature, non discriminative touch.
Through c fibres.
What information does the dorsal column/medial lemniscus system carry?
Two point discrimation, conscious proprioception and vibration sense from skin. Carried in large primary afferents, synapse near medulla.
What is the fasciculus gracilis?
Bundle of axon fibres in posterior column medial lemniscus pathway. Conveys info from lower limb such as vibration, 2 point discrimination.
What is the fasciculus cuneatus?
Tract of nerves carrying info mostly from the arms. Fine touch, vibration and proprioception information from spinal nerves located in dermatomes C1-T6.
What information is carried in corticospinal tracts?
Descending tract of upper motor neurons.
Voluntary movement, particularly fine movements of hands.
What are stellate neurons?
Cortical layer IV interneurons (axons remain in cortex). Spiny stellate cells are excitatory, smooth cells are GABAergic inhibitory neurons.
Receive excitatory synaptic fibres from the thalamus and process feed forward excitation to layer IV pyramidal cells.
From which cortical layer do axons leave the cerebral cortex?
V
What is the red nucleus?
Rostral midbrain nucleus involved in motor coordination
What is the uncus?
“bump” - anterior extremity of the Parahippocampal gyrus
Part of olfactory cortex
What is alpha gamma coordination?
When actively contract extrafusal fibres (alpha), contractile portion of intrafusal fibres (gamma) also contracts. `
What is Broca’s area?
Area associated with fluid speech. posterior inferior frontal gyrus (pars opercularis and pars triangularis) of the dominant hemisphere (left)
Which part of V1 maps peripheral vision and which part maps vision from the macula?
Anterior half maps peripheral vision
Posterior part maps high acuity vision from macula
What is the “where” stream of vision?
Dorsal stream to parietal lobe
What is the “what” stream of vision?
Ventral stream occipital->temporal lobe
Where does facial recognition occur?
Fusiform face recognition part of ventral stream
between parahippocampal gyrus/inferior temporal cortex.
Present in both left and right hemispheres but right hand side is crucial.
What is stereognosis?
Mental perception of depth/3D shape by tactile perception
Where is the premotor cortex?
Frontal lobe - posterior border along precentral sulcus, no anatomical anterior border
What is the planum temporale?
Important part of wernicke’s area (language interpretation). Located posterior to the auditory cortex (Heschl’s gyrus) within the Sylvian fissure.
Which brain part is involved in interpretation of written language?
Angular gyrus
neurological damage here can cause agraphia, inability to write
Where is V1?
In the Calcarine sulcus in the medial occipital lobe of the brain
What is the circle of Willis?
cerebral arterial circle - circulatory anastomosis that supplies blood to the brain and surrounding structures
What is the Nucleus basalis of Meynert?
a group of neurons in the substantia innominata of the basal forebrain which has wide projections to the neocortex and is rich in acetylcholine and choline acetyltransferase
(this degenerates early in AD)
What are the spinocerebellar tracts?
The spinocerebellar tracts occupy the periphery of the lateral funiculus and carry proprioceptive and cutaneous information from Golgi tendon organs and muscle spindles to the cerebellum for the coordination of movements
Which nucleus is associated with the dorsal spinocerebellar tract? (dorsal aspect of the lateral funiculus, superficial to the lateral corticospinal tract)
The ipsilateral thoracic nucleus of Clarke
Which cranial nerves contain somotosensory fibres?
V trigemenal (sensory to face, cornea, nasal cavity & mouth (touch, pain temperature)) IX glossopharyngeal (afferents to back of tongue) X vagus (somatic afferents to ear, larynx)
What is cranial nerve IX?
Glossopharyngeal:
taste, somatic afferents to back of tongue, visceral afferents sense carotid blood pressure and O2, secretion of saliva
Where is the Parabrachial nucleus?
also known as the parabrachial complex, it is an area in the dorsolateral pons that surrounds the superior cerebellar peduncle as it enters the brainstem from the cerebellum
C-fibres from spinoparabrachial tract end here
What is Allodynia?
central pain sensitization (increased response of neurons) following normally non-painful, often repetitive, stimulation. leads to the triggering of a pain response from stimuli which do not normally provoke pain
What neurotransmitter is secreted by the raphe nucleus?
5HT
What is the locus coeruleus?
locus coeruleus is a nucleus in the pons of the brainstem involved with physiological responses to stress and panic. It is a part of the reticular activating system. The locus coeruleus is the principal site for brain synthesis of norepinephrine (noradrenaline).
Descending noradrenergic neurons have an analgesic effect.
What is Clarke’s nucleus?
posterior thoracic nucleus - group of interneurons found in the medial part of lamina VII, also known as the intermediate zone, of the spinal cord. - spinocerebellar tract
Which cranial nerves are somatosensory?
V trigeminal (main somatosensory cranial nerve), IX glossopharyngeal (to back of tongue), X vagus (somatic afferents to ear, larynx)
What is Trigeminal neuralgia?
neuropathic pain that feels as if it is coming from part of the territory supplied by the trigeminal nerve
What is the corticobulbar tract?
controlling many facial muscles, it arises from contralateral and ipsilateral cortex (and runs in parallel with CST)
The fibres leave the internal capsule and enter the basilar part of the pons as numerous bundles. They synapse on alpha motorneurons or interneurons in the brain stem, desuccate or directly innervate cranial nerves. Provide bilateral descending control.
What is the result of an upper motor neuron lesion?
Spasticity and hyperreflexia due to less inhibition
Which tract is involved in keeping us upright?
vestibulospinal tract
lost inhibition causes decerebrate rigidity
What is the nucleus ambiguus?
group of large motor neurons deep in medullary reticular formin → speech, swallowing
What is the difference between a sulcus and fissure?
A sulcus is shallower and between gyri. A fissure is between lobes or hemispheres.
What is lateral medullary syndrome?
Damage to Posterior Inferior Cerebellar Artery which supplies the dorsolateral medulla.
lateral medullary syndrome: vertigo, hiccups, initially abnormal stabbing pain over the ipsilateral face then loss of pain and temperature sensation over the contralateral side of body (spinal trigeminal nucleus involvement, hoarseness, decreased gag reflex
What are the Raphe nuclei?
Groups of serotonergic neurons (where SSRIs act) distributed near the midline of the brainstem along its entire rostro-caudal extension
what is an aneurysm?
an excessive localized swelling of the wall of an artery.
what is the lentiform nucleus?
putamen + globus pallidus
What is the neostriatum?
putamen + caudate nucleus
A lesion where causes hemiballismus?
Subthalamic nucleus
Which disorder is caused by striatal degeneration?
huntingtons disease
What is the basolateral nucleus?
largest division within the amygdala plays a key role in attaching emotional significance to a stimulus. The outputs include fibres passing to the cerebral cortex- limbic association cortex, hippocampus and prefrontal cortex
What do the Edinger-Westphal nuclei do?
Edinger–Westphal nuclei provide preganglionic input to the ciliary ganglion mediating the pupillary light reflex and accommodation
What are the effects of dopamine in the SN pars compacta?
excites direct (Go) pathway -inhibits indirect (stop) pathway
Which area of the cortex mainly receives from the basal ganglia (via thalamus)?
SMA
What is the limbic loop through the basal ganglia?
The limbic loop through the basal ganglia:
Nucleus accumbens- ventral pallidum- dorsomedial thalamus- prefrontal cortex
What is the internal capsule?
a white matter structure situated in the inferomedial part of each cerebral hemisphere of the brain. It carries information past the basal ganglia, separating the caudate nucleus and the thalamus from the putamen and the globus pallidus.
