S2A Flashcards
Number of spinal nerve pairs
31
Autonomic Nervous System regulates:
involuntary functions involving viscera and/or homeostasis
Type of CNS matter neuron cell bodies are found in:
Grey matter; Retinas
PNS location of neuron cell bodies:
Autonomic ganglia Enteric nervous system
White matter (centrally) and nerves (peripherally) are formed by:
Axons
Axons in white matter and nerves form:
Tracts
Location of caudal tip of spinal cord:
Opposite L1-2
Location of spinal cord enlargements:
Cervical (C5-T1) Lumbosacral (L1-S2)
Dorsal and ventral nerve roots unite where:
at each intervertebral foramen
Lumbar and sacral roots extend inferiorly forming what structure?
Cauda Equina
Cutaneous territory served by one dorsal root is called:
Dermatome
Block of muscles controlled through one root is called:
Myotome
Segmental organisation of spinal cord is defined by what?
The nerve root pairs
Name fossae of cranium
Anterior Fossa
Middle Fossa
Posterior Fossa
Three layers of meninges
Dura
Arachnoid
Pia
Two ‘reflextions’ of dura that stabilise brain by occupying deep fissues:
Falx and Tentorium
Falx and Tentorium
Reflections of Dura that stabilise the brain by occupying deep fissues. Falx stabilises the longitudinal fissue; Tentorium stabilises the transverse fissure.
Location of CSF within meninges
Subarachnoid space
Is there CSF within the subdural and extradural spaces?
No - they are normally only potential spaces
Two layers of dura:
Periosteal and meningeal
When do the periosteal and meningeal layers of the dura separate and why?
At certaint locations they separate to enclose the dural venous sinuses that drain blood from many cerebral veins.
Role of dural venous sinuses:
To drain blood from many cerebral veins and reabsorb CSF
Largest dural venous sinus
Superior sagittal sinus within the falx
Label:
Clockwise:
Dorsal root
Ventral root
Intervertebral disc: Annulus Fibrosus and Nucelus Pulposus
Foramen transversarium/Transverse foramen
Spinal nerve in perineurium
DRG
Dura
Fat in epidural space
Label:
Label:
Label
Rostral
Towards “beak” or “nose”; towards the tip of the frontal lobe
Caudal
Towards the feet/tail
Ventral
Below the brain; anterior to spinal cord
Dorsal
Above the brain; posterior to the spinal cord
Name of fissure formed by the two sides of the forebrain (prosencephalon)
Longitudinal fissure
What structure is located deep to the longitudinal fissue, below the falx and formed by axons passing from one side of cortex to the other
Corpus callosum
What structure is lined by the tentorium and divides the cerebrum and cerebellum?
Transverse fissure
Sulci; sulcus
Valleys (of cortex)
Gyri, gyrus
ridges (of cortex)
Border between frontal lobe and parietal lobe
Central sulcus
Structurally - post-central gyrus
Functionally-
Primary somatosensory cortex
Structurally - pre-central gyrus
Functionally-
Primary motor cortex
Structure separating temporal lobe from lobes dorsal/superior to it.
Lateral fissure
Insula
Portion of cerebral cortext located in the medial wall of the laterl fissure that is not part of the four lobes.
Which structures occupy the posterior cranial fossa?
Brainstem and cerebellum
Most cranial nerves originate from which structure of the brain?
Brainstem
Brainstem attaches to which major CNS structures
forebrain, spinal cord, cranial nerves and cerebellum
What structures occupy the anterior cranial fossa?
Ventral side of frontal lobe
Which structures occupy the middle cranial fossa?
Temporal lobes
Decussation of CN2 occurs at which midline ventral landmark?
Optic chiasm
Pituitary stalk and mammillary bodies are parts of what diencephalon structure?
Hypothalamus
Calcarine sulcus/fissure
The calcarine fissure (or calcarine sulcus) is an anatomical landmark located at the caudal end of the medial surface of the brain.
Parietal-occipital sulcus
Sulcus separating the parietal and occipital lobes
Cingulate sulcus
A long curving sulcus that extends forwards from occipital lobe into frontal lobe.
The “limbic system’ is formed by what structures?
The cingulate gyrus and medial temporal cortex
Label
Within the medial temporal lobe ( which is part of limbic system, there is a specialised area of the telencephalon known as:
Hippocampus
What structure of the brain is found anterior to the hippocampus formed by a small cluster of grey matter in each hemisphere
Amygdala
Major components of diencephalon:
Thalamus and hypothalamus
Structure in brain connected ventrally to hypothalamus
Pituitary gland via the infundibulum/infundibular stalk/pituitary stalk (synonyms)
The lumen of the neural tube forms:
The ventricular system
Which ventricles are found within the telencephalon?
Lateral ventricles
Which ventricles are found within the diencephalon?
Third ventricle
Which part of the ventricular system is found within the midbrain?
Cerebral aquaduct
Which ventricles are found within the hindbrain?
Fourth ventricle
Where does CSF exit the ventricular system and what does it enter and through what is it reabsorbed?
Several exist aperatures allow the CSF to enter the subarachnoid space and be reabsorbed into the dural venous sinuses
Which cord segments make up the cervical enlargement?
C5-T1
Which cord segments make up the lumbrosacral enlargement?
L1-S2
Sympathetic output for the entire body is provides by which cord segments?
T1-L1
The adult spinal cord is what proportion of the total vertebral canal?
2/3 the length
Which section of the spinal cord have long intradural segments?
Lumbosacral region
Conus medullaris
The tapered end of the spinal cord
The long tubular sac of dura extends from brain to:
Sacrum
The lumbo-sacral nerve roots that have long intradural segments are collectively known as:
Cauda equina
Dorsal and ventral nerve roots join together at what foramen and distal to what CNS structure?
Intervertebral foramen; DRG
The central-peripheral border of the nervous system is located where?
When the dorsal and ventral nerve roots join together to form the spinal nerves
When the dorsal and ventral roots join to form the spinal nerve, the nerve has left the spinal cord and is part of the peripheral nervous system.
What happens to the dura as each nerve exists the CNS?
The dura merges with the perineurium of the nerve
Which nerves emerge from above their respective vertebra and which emerge from below?
Spinal nerves C1-7 emerge from above vertebrae C1-7.
Spinal nerve C8 emerges between C7 and T1.
The 12 thoracic and 5 lumbar spinal nerves emerge below their corresponding vertebra.
At what location is the nerve root most constrained?
When it passes through the intervebral foramen.
How can a disc herniation impact on nearby nerve roots?
Compression of nerve roots
From where can a sample of CSF be safely collected?
CSF can be collected for diagnostic assay, typically by inserting a long needle into the subarachnoid space around the cauda equina. This procedure is a lumbar puncture.
A chain of what runs adjacent to the vertebral column on either side?
Sympathetic ganglia
Sympathetic ganglia are found adjacent to which vertebrae and which nerves supply them??
3 cervical ganglia, T1 - L1/L2, 4 lumbar and 4 sacral ganglia
SUPPLIED by T1-L1/L2
Preganglionic efferent axons and post-ganglionic axons of the sympathetic nervous system synapse where?
Within the sympathetic trunk
Why is sympathetic motor innervation to the head supplied by T1 via cervical ganglia?
Cranial nerves do not contain sympathetic axons
Where are the parasympathetic ganglia located?
In or near the end-organs
Where are the parasympathetic ganglia of the cervical, lumbar and thoracic spinal nerves?
There are no parasympathetic outputs from cervical, lumbar and thoracic cord levels.
Parasympathetic innervation of viscera is via which group of nerves ?
Cranial nerves (particularly the vagus nerve) and Sacral nerves S2,3 and 4.
What neurotransmitters are released via sympathetic efferents?
Pre-ganglionic: Acetylcholine
Post-ganglionic: Noradrenaline
What neurotransmitters are released via parasympathetic efferents?
Both pre- and post-ganglionic parasympathetic efferents release Acetylcholine
Dermatome
The region of skin that receives sensory innervation from one spinal cord segment.
Myotome
The musculature that has motor innervation from one spinal cord segment.
What composes a sensori-motor unit
Grouped together, a dermatome, a myotome, the spinal nerve and one side of the corresponding spinal cord segment form a single sensori-motor unit.
Which spinal nerve usually has no dermatome?
C1
Distal nerves innervate individual muscles. How does this differ from myotomes?
Limb myotomes control movements which means that they cover groups of muscles.
Three tendon jerk reflexes of the upper limb are:
Biceps jerk - elbow flexion
brachioradialis jerk - supination
tricepts jerk - elbow extension
What is the main myotome for the biceps jerk?
C5
What is the main myotome for the brachioradialis jerk?
C6
What is the main myotome for the triceps jerk?
C7
Two tendon jerk reflexes of the lower limb:
Knee jerk - knee extension
Ankle jerk - plantarflexion
What is the main myotome for the knee jerk?
L3
What is the main myotome for the ankle jerk?
S1
True or false:
While there may be a key myotome for a particular movement, movements at larger joints typically involve two or three consecutive myotomes.
True
What is the central canal of the CNS?
A narrow cylindrical cavity which is the ventricualr component of the spinal cord.
Label
Why are the neurons of the dorsal root ganglion atypical?
- No dendrites
- two axons: one primary afferent in the peripheral nerve and one central axon ascending the spinal cord.
The ventral horn of a cord segment and ventral root axons together control what?
One myotome.
The dorsal horn of a cord segment and dorsal root axons together control what?
One dermatome.
Peripheral sensory neurons have their cell bodies in the dorsal root ganglia.
Where are the motor neuron cell bodies located?
In the ventral horn.
Synonyms for anterior horn cells?
Alpha-motor neurons
Lower motor neurons
Why are lower motor neurons called the final common pathway?
LMNs are the only neurons which have peripheral axons to directly activate muscles. The CNS can only influence action via LMN.
Motor tone:
The degree of contraction in a muscle whien it is not being deliberately used; the degree of baseline contraction due to ongoing low rate of signals in LMN axons.
LMNs are primarily response for: (3)
- muscle tone
- voluntary muscle contraction
- reflex responses
Tract:
Bundle of axons in CNS white matter with a defined functional role; provides one synaptic connection between two populations of neurons. ie. a particular parthway with several neurons communicating will be contain multple tracts.
What three pathways are particularly important in the spinal cord and tested for in limb function.
Touch pathway (DCML pathway)
Pain pathway (STT pathway)
Motor pathway (voluntary movement) (CST pathway)
Note: “You need to know each of these pathways in sufficient detail to understand the effects of focal lesions at various levels in the nervous system. Therefore it is important to learn the locations and functions of the relevant spinal cord tracts. Use this learning to explain or predict the clinical effects of focal lesions of differing sizes in various locations at various levels.”
Name the five distinct modalities of somatosensory information tested for in a neurological examination (these inputs are organised within the ascending tracts):
Tough
Pain
Vibration
Proprioception
Temperature
Three alternative destinations incoming axons in a dorsal root travel to:
- enter the ipsilateral dorsal colum of white matter and ascend to the medulla
- enter the grey matter and synapse in a dorsal horn (also ipsilateral)
- synapse in a different grey matter e.g. the ventral horn
Which somatosensory modalities give input to the dorsal column white matter?
light touch, proprioception and vibration
Where is the first synapse for neurons in the dorsal column?
Brainstem nucelus (above the spinal cord):
In the gracile and cuneate nuclei of the medulla oblongata afterwhich they decussate and enter the medial lemniscus
Input from light touch, vibration and proprioception travel to the brainstem nucleus via the dorsal column tracrt. What is the next tract in their pathway?
Medial lemniscus tract
The dorsal column-medial lemniscus pathway carries information about what somatosensory modalities?
Light touch, proprioception and vibrations
Which somatosensory modalities give input to the dorsal horn?
Pain and temperature
Pain and temperature inputs to the CNS terminate by synapsing where?
In the dorsal horn
Dorsal horn second-order neurons that relay pain/temperature information to the brain form what tract?
The spinothalamic tract (STT).
The spinothalamic tract is the major part of what pathway?
Anterolateral system
From which spinal cord segments do the pelvic organs get their parasympaathetic innervation?
S2,3 and 4
Which cranial nerves have parasympathetic functions?
Vagus
Glossopharengeal
Facial
Oculomotor
The upper limb dermatomes are the same as the nerve roots of the brachial plexus.
These are:
C4-T1/2
The lower limb dermatomes (excluding buttocks) are the nerve roots of the femoral and sciatic nerves. These are:
L2 to S2
Which nerve root supplys the middle fingers?
C7
Which nerve root supplies the umbilicus?
T10
Which nerve root supplies the big toe?
L5
Which spinal segment has no dermatome?
C1
Movements are larger joints typically involve how many myotomes?
Two or three consecutive myotomes
The anterolateral system in the spinal cord carries afferent or efferent signals?
Afferent
The anterolateral system is ascending or descending?
ascending
The anterolateral system carries which sensory modality?
pain and temperature
The spinothalamic tract is part of which system/pathway?
Anterolateral system
The lateral corticospinal tract is ascending or descending and is responsible for control of what?
motor control
descending
Cuneate fasiculus is where relative to gracile fasciculus?
lateral
Gracile fasiculus is where relative to cuneate fasciculus?
medial
The narrow band of white matter that sensory axons pass through on entering the spinal cord is called what?
Dorsal root entry zone
Synaptic input to spinal motor neurons occurs where?
within the ventral horn
At which parts of a lower motor neuron can lesions occur?
ventral horn
Ventral root
peripheral nerve
neuromuscular synapse
What is muscle tone?
The degree of contraction in a muscle when it is not being deliberately used
What is “tonic activity of LMNs”?
The background baseline activity of LMNs. It results in low-level contraction due to the ongoing low rate of signals in LMN axons.
When LMN tonic output is reduced, muscles lose tone and posture will often be impaired. When the muscles become floopy as a result, the neurological terms to describe this are:
Flaccid
hypotonic
Where does the DCML pathway decussate?
In the brainstem at the caudal medulla.
The DCML pathway decussates at the caudal medulla. What is the next tract in this pathway?
Medial lemniscus
Where does the spinothalamic tract decussate?
In the spinal cord at about the same level as the cell bodies of the STT axons.
Light touch, proprioception and vibration information ascend in the spinal cord at what side of the cord relative to their dermatome?
The dorsal column tract ascends ipsilateral- on the same side as its dermatome
Pain and temperature information ascend in the spinal cord at what side of the cord relative to their dermatome?
Contralaterally; They ascend on the side opposite their dermatome.
What are the three tracts found in the anterolateral system?
and which is the most important?
Spinothalammic tract < most important
spinoreticular tract
spinomesencephalic tract
There are two spinocerebellar tracts that take up signals for unconscious proprioception.
How do these tracts differ from the dorsal columns and STT?
The two spinocerebellar tracts do not decussate.
That is, the right cerebellar hemisphere receives proprioceptive information from the right limbs.
The corticospinal tract provides a direct linkage from where to where?
Cerebral cortex to spinal cord ventral horns
The majority of corticospinal axons decussate where and form what tract?
The majority (80-90%) of corticospinal axons decussate and form the lateral corticospinal tract in spinal cord white matter at the spino-medullary junction.
the lateral corticospinal tract is crucial for what?
controlling voluntary movements in the limbs, especially more distal actions such as using your hands.
The decussation of the DCML pathway is more or less at the same level to but dorsal to the main decussation of what tract?
The corticospinal tract which then forms the lateral corticospinal tract with the crossed fibers and the non corssed fibers (10-20%) form the anterior corticospinal tract
What part of the cortex is the main site of origin for corticospinal neurons?
The primary motor cortex
What would be the main symptom if the corticospinal tract is impaired?
The primary clinical deficit is weakness in the myotomes that lose UMN inputs.
What is a monosynaptic reflex?
Has one synapse; the afferent input connects directly to the efferent neuron
How does a polysynaptic reflex differ from a monosynaptic reflex?
polysynaptic reflexes have one or more interneurons used to link input to output
What are muscle spindles?
The sensory receptors embedded within most muscles
Do receptors in tendons provide input to deep tendon reflexes?
no; muscle spindles (receptors in muscles) are activated by targeting the tendon
Monosynaptic reflexes are also called what
stretch reflex
What are spindle afferents?
The axons going to the spinal cord in the dorsal root from muscle spindles (sensory receptors) in muscle
Where do spindle afferents in monosynaptic reflexes synapse and what do they synapse with?
in the ventral horn directly to lower motor neurons for the same muscle in the same spinal cord segment
The presence of a stretch reflex indicates what?
That a substantial number of LMNs are intact.
Note:
The reflex circuit is not damamged bya UMN but the sensitivity iis altered by UMN control (inhibition)
Abnormally brisk tendon jerks (stretch reflexes) are a sign of what?
Abnormal UMN function - UMNs should inhibit tendon jerks to a certain degree. Damage inthe corticospinal tract would result in disinhibition of the tendon jerk.
What will occur upon stimulation of the sole of the foot if a Babinski sign is not elicited?
involuntary plantarflexion of the big toe
What is a babinski sign?
involuntary dorsiflexion of the big toe
“an upgoing plantar”
The babinski sign relies on circuitry from which levels of the spinal cord?
L5 and S1
Note:
It is a polysynaptic reflex with circuitry in L5 and S1 levels of the spinal cord. Otherwise the physiology of the plantar reflex is poorly understood, except that it has been shown empirically that the normal response is dependent on normal corticospinal inputs to those levels. The abnormal response is a more primitive spinal level reaction that is “uncovered” if there is a UMN lesion.
Although the circuitry is not well understood, the plantar reflex is a reliable and important neurological sign that is routinely tested in physical examination.
Name two fontanelles formed by the coronal sutures
Anterior and posterior fontanelles
The spinomedullary junction occurs at the level of what cranial foramen?
Foramen magnum
The foramen magnum is at the level of what brainstem landmark?
Spinomedullary junction
The sellic turcica is also known as what fossa?
Hypophysial fossa
The tentorium forms the roof of what?
The posterior cranial fossa
Label:
Two layers of the dura mater
Periosteal and meningeal layer
Name of internal cranial periosteum
periosteal later of dura mater
Subarachnoid space contains what?
filled with CSF
contains nerve roots and blood vessels
Which of the three meninges follow the contours of the sulci?
Pia mater
Dura mater and arachnoid are supplied by which arteries; derived from which artery?
Meingeal arteries derived from the external carotid artery
Of the three meningeal arteries, which supplies the most area?
Of anterior, middle and posterior meningeal arteries, the middle meningeal artery covers much more area.
What is the meningeal layer of dura that occupies the longitudinal fissure?
Falx cerebri
What are arachnoid granulations?
Numerous small protrusions of arachnoid into the larger dural sinuses
What is the purpose of arachnoid granulations?
To export CSF from the subarachnoid space - removal of CSF to balance its ongoing production
The tentorium cerebelli occupies which cortical fissure?
Transverse fissure
What is the role of the falx and tentorium?
To help stabilise the brain during rapid or violent head movements
What is an extradural haematoma and what blood vessels cause them?
Extradural haematoms is a space-occupying lesion in the potential extradural space.
Skull fractures or other head injuries that cause bleeding from a meningeal artery into the extradural space cause these types of haematomas.
What is a subdural haemorrhage and what vessels cause it?
A subdural haemorrhage is bleeding into the potential space between dura and arachnoid.
This is more often due to the tearing of a vein, internal to the dura.
What is a subarachnoid haemorrhage and what can cause it?
Rupture of an aneurysm or penetrating trauma can cause a subarachnoid haemorrage in which blood spreads around the subarachnoid space.
What is the term used to describe bleeding within the brain, deep to the pia?
Intracerebral haemorrhage
aka
intraparenchymal haemorrhage
Which nerves originate from the brainstem?
Cranial nerves 3-12
Label:
Of the paranasal sinuses, which is the largest?
Paranasal sinuses - 4 paired air filled spaces (maxillary, frontal, sphenoidal, and ethmoidal)
The largest are the maxillary sinuses
What separates the oral cavity from the nasal cavity?
The hard and soft palate
The nasal and oral cavities lead back to what structures?
Pharynx.
Anterior to the pharynx and oesophagus is the larynx which is inferior to the epiglottis.
Where are the components of the ear housed?
the petrous part of the temporal bone
How is the tympanic cavity anteriorly connected to the nasopharynx?
Via the auditory tube.
The middle ear is also called the ?
Tympanic cavity
To what is the tympanic cavity connected posteriorly?
Mastoid air cells
What does the hindbrain develop into?
lower brainstem and cerebellum
Where is the midbrain located?
The midbrain is the most rostral portion of the brainstem
What are the two components of the forebrain?
Diencephalon and telencephalon.
What is the telencephalon?
The cerebrum
What is a commissure?
Used to describe neural connections - it means a more horixontal left-right connection between two regions that are at the same rostro-caudal level.
Key landmark forming border between frontal and parietal lobes
Central sulcus
two functional names of cortex separated by central sulcus
precentral gyrus is the motor cortex
postcentral gyrus is the somatosensory cortex
What separates the temporal lobe from the frontal and parietal lobes?
Lateral sulcus
aka Sylvian fissure
aka lateral fissure
aka transverse fissure
What forms the medial wall of the lateral fissure?
The insula cortex
The hypothalamus forms the ventral diencephalon. What forms the landmark of this structure?
The Mammillary bodies
What marks the anterior limit of the hypothalamus?
The optic chiasm
Label:
On which sides is the diencephalon NOT surrounded by telencephalon?
Ventral side
Diencephalon starts where and ends where?
It includes what two major regions?
Are these regions largely grey or white matter?
The diencephalon spans from the optic chiasm to and including the pineal gland. The two major regions are the thalamus and hypothalamus.
These regions are largely grey matter.
What is the overall role of the thalamus?
To organise ascending inputs to go to the appropriate area of cerebral cortex
What structure is directly above the midbrain?
The thalamus?
What diencephalic structure is ventral and rostral to the midbrain?
Hypothalamus
What is the hypothalamus?
It is the command centre for the autonomic nervous system and also has important interactions with memory and emotional processing.
What serves as a distinct border between the parietal and occiptial lobes on their medial aspect?
Parieto-occipital sulcus
What is a landmark for the primary visual cortex that is located in the medial cerebral cortex posterior to the parieto-occipital sulcus?
Calcarine sulcus
Where is the cingulate sulcus?
The cingulate sulcus is long and curvs inferiorly to the frontal lobe and is the superior border of the cingulate gyrus.
Where is the cingulate gyrus located?
Between the cingulate sulcus and corpus callosum
What lines the four ventricles and what type type of cell are they?
All ventricles are lined by ependymal cells which are a type of glia
The three horns of the lateral ventricle extend into which cerebral lobes?
anterior/frontal horn into frontal lobe
posterior/occipital horn into occipital lobe
inferior/temporal horn into temporal lobe
Label:
The third ventricle is framed by what structures?
Left and right thalamus
How do the lateral ventricles connect to the third ventricle?
Via the interventricular foramen
Where is the interventricular foramen located?
Anterior end of thalamus.
Where and what is the septum pellucidum
The septum pellucidum is a thin curtain of tissue that separates the two lateral ventricles when they are adjacent to the midline and superior to the thalamus
Match each brain division with the portion of ventricular system located within it:
telencephalon, diecephalon, midbrain, hindbrain
with
cerebral aquaduct, lateral ventricles, third ventricles, fourth ventricle
The telencephalon has the lateral ventricles, with a horn in each lobe (or the body of the ventricle in the parietal lobe). The diencephalon encloses the third ventricle; the midbrain has the cerebral aqueduct; and the hindbrain contains the fourth ventricle.
How much CSF is produced each 24 hours
150mL per day
What structure is dedicated to filtering plasma in order to produce CSF?
choroid plexus
Is CSF produced in spurts irregularly or slowly and continuously
CSF is produced slowly and continuously
Where is the ventricular system is the chroid plexus found?
Each of the four ventricles contain some choroid pluxes
How many exit aperatures are there in the ventricular system, where are they located and what do they do?
The three exit aperatures are located in the fourth ventricle beneath the cerebellum. CSF passes from inside the brain out to fill the subarachnoid space around the CNS via these aperatures.
there are two lateral and 1 medial exit aperatures.
Where are the arachnoid granulations found?
On the dorsal aspect of the brain projecting into the dural venous sinuses - mainly the superior sagital sinus.
What structures within the arachnoid granulations transfer the CSF into the venous blood?
arachnoid villi
If arachnoid granulations become blocked for some days, what will occur?
CSF accumulates within the ventricles resulting in hydrocephalus
What is the basal ganglia?
A group of interconnected sub-cortical nucel, arranged around the thalamus.
The larger of these are tenecephalic - being the corpus striatum and the globus pallidus.
Note - the striatum has two parts; caudate and putamen.
Two smaller basal ganglia are situated between midbrain and hypothalamus.
The caudate part of the corpus striatum has a tail that follows the lateral ventricle and curves into which lobe?
Temporal lobe
What is the hippocampus?
An atypical portion of cerebral cortex located deep to the other temporal cortex.
What structure is anterior to the hippocampus and caudate tail?
Amygdala (or amygdaloid complex)
What s the amygdala?
A cluster of sub-cortical nuclei that are important for emotiona reactions and form part of the limbic system
Where is the first synapse of the dorsal column - medial lemnisucs pathway?
In the dorsal column nucleus of the medulla.
Where does the DCML pathway decussate?
In the caudal medulla via internal arcuate fibres
Where is the first synapse of the pain/temperature pathway?
Dorsal horn in the spinal cord at the level of the primary afferent
Where is ‘crude touch’ information carried in the spinal cord?
In the anterolateral system
The spinothalamic tract can be separated into lateral and ventral for different sensory modalities. What is carried in these different regions?
Ventral - crude touch
lateral - pain and temperature
Where does the trigeminal nerve sensory fibres enter the brainstem?
At the pons, laterally- but travel the trigeminal sensory nucleaus extends up and down the brainstem
As well as the skin and eye, the trigeminal nerve also recieves sensory input for what other regions in the head?
nearly all the meninges
paranasal sinuses
nasal cavity
oral cavity (including teeth and anterior tongue)
Do intracranial blood vessels have pain receptors?
yes
Where is the principal (or chief) sensory nucleus of the trigeminal nerve?
The part of the sensory uncleus that is within the pons. The rest of the sensory nucleus extends down into the medulla (known as the spinal trigeminal nucleus) and up into the brainstem.
In which part of the trigeminal sensory nucleus do light touch afferents synapse?
Within the principle nucleus (in the pons)
In which part of the trigeminal sensory nucleus do pain/temperature afferents synapse?
They descend to synapse in the ipsilateral spinal trigeminal nucleus where they decussate in the medulla and then ascend to travel with the light touch siganls in the trigemino-thalamic tract,
For both limbs and face, the first synapse in the pain pathway is WHAT relative to that of the light touch pathway synapse location?
The first synapse for both limb and face pain pathway is caudal to that of the light touch pathway
Where might a lesion be that causes a selective pain/temperature deficit in the face but not a deficit in light touch?
A lesion in the medulla can cause a selective pain/temperature deficit in the face.
Where do most of the trigemino-thalamic axons terminate?
In the ventral posterior nucleus of the thalamus, alongside the other somatosensory tracts.
In the ventral posterior nucleus of the thalamus, the somatosensory pathway for the head is located where relative to that of the trunk and limbs?
The somatosensory pathway for the head is medial to that of the trunk and limbs in the ventral posterior nucleus of the thalamus. This is reveresed via the thalamocortical projection into the primary somatosensory cortex (head is lateral)
Week 20, somatosensory pathwyas page 3
