Nervous anatomy and physiology Flashcards
Tonic labyrinthine reflexes
Keep the axis of the head in relationship with the rest of the body
Uses information from maculae and neck proprioceptors
Dynamic righting reflexes
Stop you falling when you trip
Most profound in cats
Static reflex
When you tilt your head, the eyes intort/ extort to compensate
A vestibulo-occular reflex
In the PNS, the myelin sheath is formed by…
Schwann cells
In the CNS, the myelin sheath is formed by…
Oligodendrocytes
Collections of neuronal cell bodies, buried within the white matter of the brain are called…
Basal ganglia
The collection of white matter tracts through which the hemispheres communicate with each other is called…
Corpus callosum
Internal lobe, between the frontal and temporal lobes is called…
The insula
Area 4 (function and location)
Primary motor cortex: motor homunculus
precentral gyrus
Area 44, 45
function and location
Broca’s area of motor speech
inferior frontal gyrus
Area controlling cognitive functions of higher order-intellect, judgement, prediction, planning
Prefrontal cortex
Areas 3, 1, 2
function and location
Primary sensory area: sensory homunculus
post central gyrus
Area of the brain responsible for interpretation of general sensory info and conscious awareness of opposite half of body
Superior parietal lobule
Area of the brain which is the interface between somatosensory cortex and visual + auditory association areas
Inferior parietal lobule/ global association area
*In dominant hemisphere, contributes to language functions
Areas 41, 42
Primary auditory cortex
superior temporal gyrus
Location of the auditory association area
Posterior to areas 41, 42
In the dominant hemisphere the auditory association area is Wernicke’s area
Area of the brain responsible for the conscious appreciation of smell
Inferior surface of the temporal lobe
Receives fibres from the olfactory tract
Area 17 (function and location)
Primary visual cortex
medial surface of the occipital lobe, either side of the calcarine sulcus
Area of the brain involved in memory and the emotional aspects of behaviour
Limbic lobe (a functional area)
Contents of the limbic lobe
Cingulate gyrus
Hippocampus
Hypothalamus
Amygdala
Location of the hippocampus
Medial aspect of temporal lobe
Function of Broca’s area
Motor speech
Wernicke’s area
function and location
The auditory association area in the dominant hemisphere
Necessary for recognition of spoken word
Aphasia
Problems with speech due to damage of one or more speech areas in the brain
Myelinated axon fibres connecting corresponding areas of the two hemispheres together are called…
Commisural fibres
Myelinated axon fibres connecting one part of the cortex with another are called…
Association fibres
may be short or long
Myelinated axon fibres running between the cerebral cortex and various subcortical centres (below), passing through the internal capsule are called…
projection fibres
The narrow area between the thalamus and the caudate/lentiform nuclei, made up of projection fibres passing to and from the cerebral cortex
The internal capsule
Blood supply of the internal capsule
Middle cerebral artery
so is frequently affected in a stroke
Tract carrying motor impulses from cortex to skeletal muscles
Corticospinal/ pyramidal
Tract carrying sensory information (other than pain and temperature)
Posterior/ dorsal column
Tract carrying pain and temperature sensory information
Lateral spinothalamic tract
Fibres of the corticospinal tract synapse…
In the ventral horn
The corticospinal tract decussates…
At the decussation of the pyramids in the inferior medulla
No. of neurons making up the motor pathway
2:
UMN
LMN
(synapse in the ventral horn at the level where they exit)
The posterior/dorsal column decussates…
In the medulla
After decussation, the posterior/dorsal column is called…
The medial lemniscus
The lateral spinothalamic tract decussates…
At the level of entry
For ascending spinal tracts, which order neuron decussates?
2nd order neuron
Effect of an UMN lesion on tone…
Spasticity
Increased tone
Effect of a LMN lesion on tone…
Flaccidity
Decreased tone
Effect of a LMN lesion on reflexes
Areflexia
absent reflexes
Effect of an UMN lesion on reflexes
Hyper-reflexia
Exaggerated reflexes
EEG
ElectroEncephaloGram
Records activity of underlying neurons
Circadian rhythm
A biological system showing oscillations of ~24hrs
Demonstrated by the SCN (suprachiasmatic nuclei) of the hypothalamus - the “master clock”
Result of UMN lesion above the decussation
Contralateral spastic paralysis and hyperreflexia
Result of UMN lesion below the level of decussation
Ipsilateral spastic paralysis and hyperreflexia
Result of LMN lesion
Ipsilateral flaccid paralysis and areflexia
Melatonin is released by ……………… stimulated by ……………..
Melatonin is released from the pineal gland, stimulated by activity in the SCN (Suprachiasmatic nuclei) of the hypothalamus
Feeling of sleepiness is produced by which hormone?
Melatonin
The neurotransmitter required for wakefulness is called…
Orexin
On an EEG recording, frequency increases with…
Neuronal excitation
E.g.
anaesthesia –> sleep –> awake –> epilepsy
On an EEG recording, amplitude increases with…
decreasing neuronal excitation
Cognition definition
The integration of all sensory information to make sense of a situation
Function of the hippocampus (in learning and memory)
Formation of memories
Function of the cortex (in learning and memory)
Storage of memories
Function of the thalamus (in learning and memory)
Searches and accesses memories
The limbic system is responsible for what types of behaviour?
Instinctive (thirst, hunger, sex etc.)
Emotive (driven by reward/ punishment) - gives emotional significance to events, essential for memory
The ability to hold experiences in the mind for a few seconds. Based on different sensory modalities
Immediate/ sensory memory
Type of memory associated with reverberating circuits
Short term memory,
Often called working memory
Used for tasks such as dialling a phone number
Type of memory associated with chemical adaptation at the presynaptic terminal
Intermediate long-term memory
Used to remember what you did last weekend etc…
Type of memory associated with structural changes in synaptic connections
Long-term memory
Used to remember childhood friends etc…
Anterograde amnesia
Cannot form new memories
Can be short lived or permanent following an injury
Retrograde amnesia
Cannot access (more recent) old memories
Occurs if thalamus damaged
Changes in structure in long-term memory
- increase in number of presynaptic terminals
- increase of neurotransmitter release sites
- increase of neurotransmitter vesicles stored and released
Types of long term memory
Declarative/Explicit: for events, rules and language (relies heavily on hippocampus)
Procedural/Reflexive/Implicit: for acquired motor skills (independent of hippocampus)
Conversion of short-term memories to long-term memories
definition and mechanism
Consolidation
Strengthening of synaptic connections through repetition
Which cranial nerves emerge from the pontomedullary junction
VI, VII, VIII
Function of the olive
Contains the inferior olivary nucleus
What structure does the “open” part of the medulla open onto?
What part of the medulla is this?
The 4th ventricle
The posterior, superior medulla
The “closed” part of the medulla is a continuation of what structure?
What part of the medulla is this?
The central canal of the spinal cord
The posterior, inferior medulla
Function of the cerebellar peduncles
Attach the cerebellum to the brainstem
Attachments of the middle cerebellar peduncle
Cerebellum
Pons
The surface projections visible of the surface of the hypothalamus are called…
The mammillary bodies
The midline structure connecting the two cerebellar hemispheres is called…
The vermis
The ventricular space lying immediately anterior to the cerebellum is the…
4th ventricle
The part of the cerebellum above the foramen magnum…
The cerebellar tonsil
In a sudden drop in intracranial pressure, the cerebellar tonsils may herniate through the foramen magnum, this is called…
Cerebellar coning
The fissure separating the two cerebral hemispheres is called…
The medial longitudinal fissure
The structure connecting the two cerebral hemispheres is called the…
Corpus callosum
composed of commissural fibres
The fold of dura mater separating the cerebellum from the cerebral hemispheres is called…
Tentorium cerebelli
At what level does the spinal cord terminate in an adult?
L1-2
At what level does the spinal cord terminate in a new-born?
L2-3
At what vertebral level does the dura mater terminate
S2
At what vertebral level does the arachnoid mater terminate?
S2
Fate of the pia mater, inferior to the spinal cord…
Becomes the filum terminalis
What occupies the space btw the termination of the spinal cord and the dura/arachnoid mater?
Conus medularis and cauda equina (spinal nerve roots L2 -Cc1)
Correct vertebral level of a lumbar puncture on an adult
Between L3 - 4 (with adult in a foetal position)
How many pairs of spinal nerves are there?
31
8 cervical 12 thoracic 5 lumbar 5 sacral 1 coccygeal
From which arteries do the left and right vertebral arteries arise?
Subclavian
Vertebral level of bifurcation of the common carotid artery
C3/4
Which part of the brainstem does the basilar artery overlie?
Pons
The anterior cerebral artery travels in which fissure of the brain?
Great longitudinal fissure
follows the dorsal curvature of the corpus callosum
The middle cerebral artery travels within which fissure of the brain?
Lateral fissure
The posterior cerebral artery travels within which fissure of the brain?
Calcarine fissure
Blood supply of the primary motor cortex
Mainly middle cerebral artery Medial aspect (lower limb area) by anterior cerebral artery
Blood supply to the primary sensory cortex
Mainly middle cerebral artery Medial aspect (lower limb area) by anterior cerebral artery
Blood supply to primary visual cortex
Posterior cerebral artery
Blood supply to primary auditory area
Middle cerebral artery
Blood supply to area for olfaction in the brain
Middle cerebral artery
Areas of the brain supplied by the anterior cerebral artery
Medial surface of frontal and parietal lobes
Areas of the brain supplied by the middle cerebral artery
Lateral surface of frontal, parietal and temporal lobes
Areas of the brain supplied by the posterior cerebral artery
Occipital lobe
Inferomedial aspect of temporal lobe
Carotid sinus (function and pathway of sensory nerves)
Pressure receptor, monitors flow of blood to the head
Sensory nerves from it run in the glossopharyngeal and vagus nerves
Carotid body (function and pathway of sensory nerves)
Contains chemoreceptors sensitive to anoxia
Sensory nerves from it run in the glossopharyngeal nerve
detection of anoxia = ↑HR, RR, BP
The dilatation located in the terminal common carotid artery/proximal ICA is called…
The carotid sinus
The area on the posterior wall of the terminal common carotid artery is called…
The carotid body
The dural venous sinuses draining the brain are located between which layers inside the skull?
Between the periosteum and cranial dura
The dural venous sinuses drain into…
IJV
What veins drain into the cavernous sinus?
Superior ophthalmic veins
potential route of infection from extra to intracranial
Why is the brain at risk of infection through venous routes?
Veins in the brain and venous sinuses do not have valves to prevent backflow from outside to inside the cranium
Bony attachments of the falx cerebri
Crista gali
Internal occipital protuberance
Bony attachments of the anterior edge of the tentorium cerebelli
Anterior clinoid processes
Which dural sinus runs along the attachment of the falx cerebri to the tenrorium cerebelli?
Straight sinus
The dural fold separating the cerebellar hemispheres is called…
Falx cerebella
The fold of dura mater surrounding the pituitary stalk is called…
The sellar diaphragm
The middle meningeal artery is a branch of which artery?
The maxillary artery
The middle meningeal artery supplies…
The dura mater
The anterior horn of the lateral ventricle lies within which lobe?
Frontal lobe
The body of the lateral ventricle lies within which lobe?
Parietal lobe
The posterior horn of the lateral ventricle lies within which lobe?
Occipital lobe
The inferior horn of the lateral ventricle lies within which lobe?
Temporal lobe
The lateral ventricles are connected to the 3rd ventricle by the…
Interventricular foramen/ foramen of Monro
Location of the 3rd ventricle
In the diencephalon
Location of the 4th ventricle…
Btw the brainstem and the cerebellum
What structure absorbs CSF back into the general circulation?
Arachnoid villi in the sagittal sinus
Function of gamma motoneurons
Innervate the contractile ends of intrafusal muscle in the muscle spindle
This stretches the central area of the intrafusal fibres = fewer APs fired
When do gamma motoneurons fire?
and why
With alpha motoneurons so the spindle shortens with the muscle so can keep transmitting sensory info
What increases/ decreases muscle spindle discharge of APs?
Muscle contracts = spindle stretched = ↓ APs
Muscle relaxes/stretched = spindle relaxes = ↑ APs
What increases/ decreases GTO discharge of APs?
Muscle contracts = ↑tension in GTO = ↑APs
Muscle relaxes = ↓tension in GTO = ↓APs
3 results of the stretch reflex
- agonist contracts (monosynaptic reflex)
- antagonist relaxes (activation of inhibitory interneurons - reciprocal inhibition)
- sensory info ascends in dorsal column
3 results of the inverse stretch reflex/ GTO reflex/ clasp knife reflex
- agonist relaxes (activation of inhibitory interneurons)
- antagonist contracts (activation of excitatory interneurons)
- sensory info ascends in dorsal columns
Function of the Golgi tendon organ
Monitors muscle tension
Function of the muscle spindle
Monitors muscle length
3 results of the flexor-withdrawal reflex
- ipsilateral flexion*
- contralateral extension*
- info ascends in the spinothalamic tract
*through stimulation of excitatory/inhibitory interneurons
The middle cerebellar peduncle is made up of…
Motor nerve fibres
The cerebral peduncles are made up of…
Sensory and motor fibres
The vertebral and basilar arteries (vertebro-basilar system) supply
Brainstem
Occipital lobes
Cerebellum
Pain occurring when specific peripheral sensory neurons respond to noxious stimuli
Nociceptive pain
Pain usually localised to site of injury
Usually responds to conventional analgesics
Pain initiated/caused by a primary lesion in the somato-sensory nervous system
Neuropathic pain
Aα and Aβ fibres
structure and function
Large diameter, myelinated
Proprioception, light touch
Aδ fibres
structure and function
Medium diameter, lightly myelinated
Nociception (fast pain)
C fibres (structure and function)
Small diameter, unmyelinated
Non-noxious temperature
Itch
Nociception (slow pain)
Exaggerated response to noxious and non-noxious stimuli (increased perception of pain)
(name and when it occurs)
Hyperalgesia
Occurs with tissue injury and inflammation (inflammatory mediators cause nociceptor changes)
Decreased threshold for nociceptor response (non-noxious stimuli perceived as pain) is called…
Allodynia
occurs centrally as a clinical feature of many conditions
An injury caused by a blunt force is called…
A laceration
An injury caused by a sharp object is called…
An incised wound
Fracturing of the orbital plates caused by a fall onto the back of the head…
Contre-coup fracture
Fracture encircling the foramen magnum caused by a fall from height, leading to the skull base and cervical spine being forced together…
Ring fracture
How does increased ICP cause death?
Compression of the brainstem due to herniation of the cerebellar tonsils into foramen
magnum
Main cause of extradural haemorrhage…
Damage to an artery with skull fracture (often MMA)
arterial bleeding = high pressure
A lucid interval in which a patient seems ok following a head injury then deteriorates catastrophically later is often due to…
Extradural haemorrhage
May be seen with subdural haemorrhage
Mot common cause of subdural haemorrhage…
Trauma without a fracture
Relative movement between brain and dura causes veins to stretch and tear (bleeding is from veins so accumulates slowly)
Most common cause of subarachnoid haemorrhage…
Rupture of a cerebral artery “berry” aneurysm
Commonest cause of traumatic basal subarachnoid haemorrhage (TBSAH)
Abrupt rotation of the head –> rupture of vertebra-basilar circulation
(death probably due to rotation of the brainstem at the same time)
Commonest cause of death in fatal head injuries
Cerebral oedema (rapid result of brain injury) –> brain swelling –> raised ICP + coning
Cerebral contusion
meaning
Bruising to the brain
The thin sheet separating the lateral ventricles in the mid-sagittal plane is called…
Septum pellucidum
The bundle of fibres linking the hippocampus to the mamillary bodies is called…
The fornix
In what part of the brainstem is the substantia nigra
Midbrain
Location of the red nucleus
In the midbrain, posterior to the substantia nigra
What is the name of the hole in the middle of the spinal cord?
Central canal
Cranial nerves with a parasympathetic component
III, VII, IX, X
Origin of the oculomotor nerve
Midbrain
Origin of trochlear nerve
Posterior midbrain
Origin of trigeminal nerve
Pons
Origin of abducent nerve
pontomedullary junction
Origin of facial nerve
pontomedullary junction
Origin of vestibulocochlear nerve
pontomedullary junction
Origin of glossopharyngeal nerve
Medulla (lateral to olive)
Origin of vagus nerve
Medulla (lateral to olive)
Origin of accessory nerve
Medulla (lateral to olive)
+ spinal roots
Origin of hypoglossal nerve
Medulla (medial to olive)
Somatic motor actions of the trigeminal nerve (V3)
Muscles of mastication
Digastric
Tensor veli palatine
Tensor tympani
EEG waves when awake and alert
β waves
V. high frequency
Low amplitude
EEG waves when awake and relaxed
α waves
High frequency
High amplitude
EEG waves in stage 1 slow wave sleep
θ waves
Low frequency
High amplitude
EEG waves in stage 2 slow wave sleep
θ waves (low frequency, high amplitude) with sleep spindles
EEG waves in stage 3 slow wave sleep
δ waves (v. low frequency and high amplitude) with episodes of faster waves
EEG waves in stage 4 slow wave sleep
Exclusively δ waves
EEG waves in REM sleep
Mimic β waves
Fibres activating the pupillary reflex do not travel to the LGB but instead leave the optic tract to go to the…
EWN
(part of the 3rd nerve nucleus which is for parasympathetic fibres)
In the midbrain
Identifying a cervical spinal cord segment
segment, ventral horn, dorsal horn
Segment: large and oval
Dorsal horn: Long and slender
Ventral horn: Broad and large
Identifying a thoracic spinal cord segment
segment, ventral horn, dorsal horn
Segment: small and circular
Dorsal horn: slender
Ventral horn: slender
Identifying a lumbar spinal cord segment
segment, ventral horn, dorsal horn
Segment: large and circular
Dorsal horn: Bulbous and short
Ventral horn: Bulbous and short
Identifying a sacral spinal cord segment
segment, ventral horn, dorsal horn
Segment: small and circular/quadrilateral
dorsal horn: massive and ovoid
ventral horn: massive and ovoid
In rehabilitation, goals set should be…
S-pecific M-easurable A-cheivable R-ealistic/relevant T-imely
The role of lateral pathways in motor control
+ the control of these pathways
Control voluntary movements
Under direct CORTICAL control
The role of ventromedial pathways in motor control
+the control of these pathways
Control posture and locomotion
Under BRAINSTEM control
voluntary/ ocular/ vestibular… etc. input
2 lateral pathways are…
Corticospinal tract
Rubrospinal tract
2 immediate functions of the corticospinal tract
- monosynaptically excite pools of AGONIST motoneurones
2. inhibit ANTAGONIST motoneurones via interneurones
The ventromedial tract that stabilises the head and neck is called…
The vestibulospinal tract
The ventromedial tract that ensures the eyes remain stable as the body moves is called…
The tectospinal tract
The ventromedial tract that reflexly maintains balance and body position is called…
The pontine and medullary reticulospinal tracts
The pontine and medullary reticulospinal tracts innervate…
The trunk and anti-gravity muscles in the limbs
to reflexly maintain body position and balance
Area 6
+ location
Premotor and supplementary motor areas
anterior to the motor cortex - area 4
Basal ganglia making up the corpus striatum
Caudate nucleus
Lentiform nucleus
Main sign of a cerebellar lesion
Ataxia
fail to touch nose with eyes shut
Motor learning
where it happens + what it is
Occurs in the cerebellum
Compares what is intended and what happened and compensates for next time
Aim of the direct pathway
To UN-inhibit the thalamus
so it can excite the motor cortex - and you can move
Aim of the indirect pathway
To inhibit the thalamus
so it is unable to excite the motor cortex - and you don’t move
3 parts of the neural tube at 27 days
Prosencephalon (forebrain)
Mesencephalon (midbrain)
Rhombencephalon (hindbrain)
At 32 days, the prosencephalon forms the…
telencephalon
diencephalon
At 32 days, the rhombencephalon forms the…
metencephalon
myelencephalon
The telencephalon forms which adult structures
cerebral hemispheres
hippocampus
basal ganglia
The diencephalon forms which adult structures
Thalamus
hypothalamus
pituitary gland
pineal gland
the mesencephalon forms which adult structures
superior and inferior colliculi
the metencephalon forms which adult structures
cerebellum
pons
The myelencephalon forms which adult structures
medulla
All CNS cells (neurons, astrocytes, oligodendrocytes, ependymal cells) except microglia develop from…
neuroepithelial cells (lining the neural tube)
Microglia develop from…
mesenchymal cells (which migrate into the CNS)
neural crest cells break away from the neural tube and migrate throughout the embryo forming…
ganglia adrenal medulla body pigment (except eyes) branchial arches sensory neurons
Structures derived from the 1st branchial arch are supplied by…
CrN. V3 (and V2)
so it forms:
- anterior belly of digastric
- mylohyoid
- malleus and incus
- tensor tympani
- mandible and maxilla
- tensor veli palatini
- muscles of mastication (pterygoids, masseter, temporalis)
Structures derived from the 2nd branchial arch are supplied by…
Facial nerve
so it forms:
- muscles of facial expression
- trapezius, sternocleidomastoid + platysma
- stapes + stapedius
- posterior belly of digastric
Structures derived from the 3rd branchial arch are supplied by…
glossopharyngeal nerve
so it forms:
- stylopharyngeus
Structures derived from the 4th branchial arch are supplied by…
Superior laryngeal branch of vagus
so it forms:
- cricothyroid muscle
Structures derived from the 6th branchial arch are supplied by…
Recurrent laryngeal branch or vagus
so it forms:
- intrinsic muscles of the larynx
pupillary light reaction afferent and efferent
afferent = II efferent = III
corneal reflex afferent and efferent
afferent = V1 efferent = VII
Jaw jerk afferent and efferent
afferent = V efferent = V
oculocephalic reflex afferent and efferent
“dolls eyes” - eyes stay looking at the same point when head is rotated before moving
afferent = VIII efferent = III, IV, VI
Oculovestibular reflexes afferent and efferent
static reflex
dynamic vestibular nystagmus (COWS)
afferent = VIII efferent = III, IV, VI
myotome C5
elbow flexors
myotome C6
wrist extensors
myotome C7
elbow extensors
myotome C8
finger extensors
myotome T1
intrinsic hand muscles
myotome L2
hip flexors
myotome L3
knee extensors
myotome L4
ankle dorsiflexors
myotome L5
long toe extensors
myotome S1
ankle plantar flexors
