Title: BV4 / Modul 2 / Somatosensory system: Touch and proprioception

Q: What is passive tactile perception and active touching?
A: - Passive tactile perception: object pressed against the skin
- Active touching: Haptics

Q: WHat are the functions of the somatosensory system?
A: - Touch
- Pain
- Temperature
- Proprioception

Q: What can be said about touch (passive)?
A: Touch is an important sensory function, we feel objects when they are passivly pressed agaisnt our skin, e.g. when u sit or lean against the wall or u can feel ur clothes - this is passive tactile perception

Q: What does active touching allow for?
A: Active touching is what allows us to identify objects thorugh discriminative touch

Q: What is haptics?
A: Haptics is the perception of objects through active touch - it is out ability to recognize features of objects that we activly touc by activley touving them

What are ex. of features in terms of haptics?

Q: What do we feel/sense when we hold an object?
A: When u hold and touc the objects its not just the object itself that u touch and identify, but all the features that characterize the object are processed by the brain and are identified - we identify texture, contours, shape  volume and weight of what we touch - all these features of an object are detected by our hands and by specific receptorcells in our skin

Q: What is a unipolar/pseudopolar neuron?
A: Unipolar neurons have a single elongate process, with the cell body situated off to the side

Q: What can be said about the receptors for touch?
A: These receptorcells are mekanoreceptors, they are unipolar neurons also called pseudounipolar

Q: Why are unipolar neurons special?
A: They
are special because they have dendrites in the skin and they have 1
axon which starts by the dendrites in the skin so the initial segment of the
axon of this unipolar neuron is there - this is where APs are generated (not
close to the soma)

Q: What happens with the unipolar neuron when skin is touched?
A: So when the skin is touched the dendrites are activated and a receptor potential is produced and if the depolarization is stroing enough AP's will be produced in the initial segment - these AP's will be conducted in the peripheral part of the axon and these will pass the cell body and be conducted in the central part of the axon, the one that enters the spinal cord (the CNS)

Q: What is the simple structure of a pseudopolar/unipolar neuron?
A: So these neurons have 1 axon with a peripheral part (between dendrites in skin and soma) and a central part (between soma and spinal cord)

Q: Where are the cell bodies of unipolar neurons?
A: The cell bodies of these neurons (1st order neurons) are located in dorasl root ganglia, so these cells are also called dorsal root ganglion cells

Q: What can be said about the dorsal root ganglia?
A: We have 2 sets of dorsal root ganglia, each on eon either side of the spinal cord - Each ganglion is connected to one spinal cord segment

Q: Where do the axons of sensory cells enter the spinal cord?
A: The axons of the sesnory neurons of a given ganglion enter  the spinal cord in a specific segment, so we can define dermatomes, which are areas of the skin that are innervated by one spinal nerve, one dorsal root ganglion

Q: What are dermatomes?
A: They are areas of the skin that are innervated by one spinal nerve, one dorsal root ganglion

Q: HOw can we define dermatomes in the body?
A: We can define different dermatomes in the body based on the division of the spinal cord into different segments and based on the dorsal root ganglia

Q: What is clinically relevant about dermatomes?
A: This is clinically relevant to know about the different dermatomes because we can evaluate the location of a spinalcord lesion or injury or the loss of peripheral sensation attributed to damage of a specific nerve

Q: What does 2-point discrimination threshold relate to?
A: Two-point discrimination threshold relates to our ability to detect 2 separate stimuli applied at the same time in an area of the skin as 2 separate stimuli and not as a single one

Q: How can the 2-point threshold be measured?
A: Can be measured by applying 2 toothpics separated by varying distances and pressed against the skin of a test person at the same time, this person will perceive one stimulus or 2 separate stimuli depending on the distance of the 2 toothpics

Q: What happens when the distance changes when evaluating 2-point discrimination threshold?
A: When the distance is small we perceive one stimulus, but when the difference is greater we can perceive 2 stimuli

Q: How does 2-point discrimination threshold work?
A: - We have 3 neurons with their respective receptive fileds which overlaps
- If u stimulate with the short distance between the toothpics (in green) the stimulus hits mostly the centre of the receptive field of the neuron which fires a lot as seen in the green graph - but the periphery of neurons a and c are also stimulated (they will fire but only a littel), which means that the information from one neuron (b) will reach our brain and the stimulus will be received as one point and not 2
- However, when the 2 toothpics are separeted by a greater distance they will be located at the center of the receptve fileds of neurons a and c which will fire a lot and provide info to the brain of 2 separate stimuli and not just one - at this distance we will have reached a threshold that allows us to feel 2 stimuli by varying the distance between 2 stimuli applied on the skin at the same time

Q: What is the 2-point discrimination threshold?
A: It  is the minimum distance required to perceive 2
stimuli as 2 separate ones and not as 1

Q: What will happen with the 2-point discriminative threshold at an intermediate distance?
A: In the situation in red with and intermediate distance between the toothpics the three neurons will fire equally and we will not be able to perceive 2 points instead it will be a diffused sensation

Q: What can be said about the 2-point discrimination threshold in differnet areas of the body?
A: It varies
in different areas of our body, parts of the body are more sensitive (particuary the fingertips), they have the
highest tactive aquity of precision compared to ex. the arm or the back or the
legs

Q: WHich part of te body has the highest tactive aquity of precision?
A: Fingertips

Q: What is the function of the high tactive aquity of precision in the fingertips?
A: So we can discriminate small sized objects with our finger tips and not with other parts of the body like the arms

Q: What does tactile acuity look like in differnet parts of the body?
A: We can assess this tactile aquity with the 2 point discrimination threshold which is very small in the fingertips and larger in other parts of the body such as the arms the back and the legs

Q: What are the 2 things that determine the 2-point discrimination threshold?
A: - Size of the neuronal receptive fields
- Density of mechanoreceptors

Q: What can be said about neurns with small receptive fields?
A: Neurons with small receptive fields have small arborisation in the skin and tey can be stimulated by stimuli applied to small portions of the skin - these neurons with small receptive fields are located in the fingertips and in the lips

Q: What is the density of mechanoreceptors?
A: The
density meaning the number of mekanoreceptors is high in the fingertips

Q: What do several sensory neurons with small receptive fields do?
A: Several
sensory neurons wth small receptive fields will provide info to the brain and
make it possible to separate 2 or more stimuli - this contributs to our ability
to identify small features of what we touch and this is why we do
discriminative touch, active touching or haptics with our fingers to identiffy
all the fingers of an object and not e.,g our arm

Q: What can be said about the receptive fields in the arm, legs, back and shoulder?
A: In our arms, legs, back and shoulders the sensory neurons have large receptive fields and the density of mekanoreceptors is lower than in the fingertips

Q: What does the 2-point discrimination threshold measure?
A: Measures the minimal intwrstimulus distance required to perceive 2 simultaneously applied stimuli as distinct

Q: What is the 2-point discrimination threshold an indication of?
A: An indication of tactive acuity (spatial accuracy/precision of stimulus location)

Q: What are the receptorcells that provide the perception(?) about touch that allows us to perceive discrimitaive touch?
A: We have 4 main types of mechanoreceptors

Q: How are the 4 types of mehanoreceptors distributed in the skin?
A: - 2 types are in the superficial layers of the dermis just underneith the epidermis (merkel and meissners)
- 2 types in the depp layers of the skin in the dermis (pacini's and ruffini's)

Q: What is there in each pair of mechano receptors?
A: In each pair there is one rapidly adapting and one slowy adapting mekanoreceptor

Q: What can be said about merkel cell-neurite complex and meissners corpuscle?
A: Merkel and meissner have small receptive fields and therefore high spacial resolution

Q: What does the merkel cell-neurite complex allow for?
A: Merkel are responsible for our ability to perform dicriminative touch with the finest resolution, they allow us to detect very fine details

Q: What can be said about the deeper mechanoreceptors?
A: The deeper mekano receptors have large receptive fields and lower spacial resolution

Q: What is the merkel cell-neurite complex?
A: Nerve ending surrounded by a capsule of merkel cells

Q: What can be said about the innervation density of merkel cell-neurite complex?
A: High innervation density (finger)

Q: What is the % of méchanoreceptors of merkel cell-neurite complex in the hand?
A: 25% of mechanoreceptors in the hand

Q: WHat type of receptive field does merkel cell-neurite complex have?
A: Small receptive field, SA

Q: How is the adaptation of merkel cell-neurite complex?
A: Slowly adapting, SA

Q: What do merkel cell-neurite complex feel?
A: Discriminative touch with fine (highest, 0,5 mm) spatial resolution (shape and texture)

Q: What is meissner's corpuscle?
A: Several nerve ending in a capsule (connective tissure + lamellar cells)

Q: What's the innervation of meissner's corpuscle?
A: Dense innervation of the skin

Q: How many of the mechanoreceptors in the hand does meissner's corpuscle constiture for?
A: 40% of mechanoreceptors in the hand

Q: What is the receptive field of meissner's corpuscle?
A: Small receptive field (but larger than merkel), RA

Q: What type of adaptation does meissner's corpuscle have?
A: Rapidly adapting

Q: What does meissner's corpuscle sense?
A: Discriminative touch with less spatial resolution than merkel - skin deformation, motion, grip control

Q: What is ruffini's corpuscle?
A: Nerve ending and capsule (collagen)

Q: What is the innervation of ruffini's corpuscle?
A: Low innervation density (finger)

Q: How many of the mehcano receptors in the hand does ruffini's corpuscle constitute for?
A: 20% of mechanoreceptors in the hand

Q: What is the receptive field of ruffini's corpuscle?
A: Large receptive field

Q: What type of adaptation does ruffini's corpuscle have?
A: Slowly adapting, SA

Q: What does ruffini's corpuscle respond to?
A: Respond to streches of the skin and movement/finger position

Q: What is the pacinian corpuscle?
A: Layered onion-like apperance (layers of membrane), single afferent

Q: What is the innervation of the pacinian corpuscle?
A: Low innervation density (finger)

Q: How many of the mechanoreceptors in the hand does pacinian corpuscles constitute for?
A: 10-15% of mechano receptors in the hand

Q: WHat is the receptive field of pacinian corpuscle?
A: Very large receptive field, RA

Q: What type of adaptation does pacinian corpuscle have?
A: Rapidly adapting, RA

Q: What does the pacinian corpuscle detect?
A: Detect high-frequency vibratory and deep pressure stimuli (highest sensitivity for vibrations/motion), use of tools

Q: WHat is the reason why pacinian and meissner's corpuscles are RA?
A: The reason why pacini and mesissner are rapidly adapting, they fire at the beginning of the stimulus but not during the duration is bc of the mecanic properties of the cells and layers that surround the nerve ending (mekano receptor nerve temrinal)

Q: How does the pacinian corpuscle work?
A: - Pacini: when pressure is applied on the skin it will transiently activate the nerve but then the layers of lamellar cells and collagen fibers slide on each other which prevent the pressure applied to the skin from activating the nerve even if the force is mantained

Q: How does meissner's corpuscle work?
A: Its the same for meissner's as for pacinian: lamellar cells slide apart and transiently activate the nerve

Q: WHat can be said about somatosensory afference?
A: Somatosensory afference have different types of axons or fibers which is based on the axon diametre, the conduction velocity and the amount of myelin

Q: What type of axons do mechanoreceptors, transmitting info about touch, in the skin have?
A: Mekanoreceptors in the skin that transmitt info about touch have axons of the A-beta type

Q: What do A-beta axons look like?
A: - They have myelin and their conducton velocity is high, but not as high as the fibers for proprioception (Ia, and II types)

Q: What is the receptor type for proprioception?
A: Muscle spindle

Q: What is the receptor type for temperature, pain?
A: Free nerve endings

Q: What is the receptor type for pain, temp., itch, non-discriminative touch?
A: Free nerve endings (unmyelinated)

Q: Which type of afferent axon does proprioception have?
A: Ia, II

Q: Which type of afferent axon does pain, temp have?
A: A-delta

Q: Which type of afferent axon does pain, temp, itch, non-discriminative touch have?
A: C-axon

Q: What can be said about axon diametre and conduction velocity?
A: It seems the greater the diametre, the faster the conduction speed

Q: Arrange the axon types from greatest to smallest diametre?
A: - Ia, II
- A-beta
- A-delta
- C
It's the same order for fastest to slowest conduction velocity

Q: What is proprioception?
A: Perception/awareness of motion and sense of static position

Q: What is proprioceptor?
A: A receptor for self:
- Muscle receptor
- Golgi tendon organ
- Joint receptor

Q: Which receptors are there for prprioception?
A: - Muscle receptor
- Golgi tendon organ
- Joint receptor

Q: What is proprioception, elaborate?
A: Proprioception is our ability to percieve or be aware of motion, movement and also to be aware of the position of our body in the space - this is the sense of static position

Q: What are ex of proprioception?
A: - e.g. when u move ur arm u know where in space ur arm is even if u close ur eyes
- When u stand still u know where ur body is and which position it has

Q: What does proprioception allow for?
A: Proprioception allows us to not only detect movements but alos static position of our body, arms and legs - this is because we have proprioceptors which are the receptors for self

Q: Where are muscle spindles located?
A: I skeletal muscles

Q: What do muscle spindles do?
A: Inform about changes in muscle length

Q: What does the muscle spindles consist of?
A: 4-8 intrefusal muscle fibers + capsule of connective tissue

Q: How are the muscle spindles innervated?
A: Primary (Ia) and secondary (II) nerve endings

Q: Vilka karakteristiska har de nerver som förmedlar den skarpa smärtan som uppstår om vi till exempel råkat slå oss på tumme med en hammare och i vilket lamina i ryggmärgen terminerar nervfibrerna?
A: Myeliniserade nerver med högtröskliga mekanoreceptorer och långsam adaptation och hög konduktionshastighet, nervfibrerna går till lamina I

Q: Hur skiljer sig allodyni från hyperalgesi?
A: Kan förmedlas av myeliniserade A-beta fibrer

Q: I vilka ledningssystem och hjärnregioner kan man förvänta sig smärtrelaterad nervaktivitet strax efter en korsbandsskada i höger knä?
A: Vänstra spinothalamiska banan, thalamus och mediala sensoriska kortex på vänster sida

Q: Vad orsakar perifer sensitisering?
A: Ökad aktivering och mängd av membranbundna jonkanaler och receptorer

Q: Vad är kännetecknande för refererad smärta?
A: Utbredning varierar med smärtintensiet

Q: Vad ska vara uppfyllt för att säga att en patient har nociplastisk smärta?
A: 1) Smärtduration mer än 3 månader,
2) smärtans är regional eller utbredd, men inte vällokaliserad,
3) smärtan kan inte helt förklaras av nociceptiva eller neuropatiska mekanismer och
4) vid klinisk undersökning finner man ökad smärtkänslighet inom smärtande område.

Q: Amitriptylin är ett tricykliskt antidepressivt läkemedel (TCA) som är godkänt för behandling av neuropatisk smärta och kronisk huvudvärk samt som migränprofylax i Sverige. Vad tror man är den främsta anledningen till den smärthämmande effekten?
A: Hämmar återupptaget av noradrenalin

Q: Gabapentin och pregabalin är läkemedel som används vid behandling av neuropatisk och nociplastisk smärta. Den analgetiska effekten av dessa läkemedel är kopplad till vilken faktor?
A: Calciumjonkanaler

Q: Vilket stämmer inte gällande funktionen för de två typerna av retinala ganglieceller?
A.
Dom har ON-center och OFF-center responser.
B.
De har antagonistiska responser.
C.
De upptäcker kontraster som inte är över absolut belysningsstyrka.
D.
Information om ökningar och minskningar i belysningsstyrka för de två typerna av ganglieceller går till hjärnan separat.
E.
ON-center bipolära celler minskar aktiviteten hos ON-center ganglieceller.
A: ON-center bipolära celler minskar aktiviteten hos ON-center ganglieceller.

Q: Vad karaktäriserar stavar och tappar för spatial upplösning, färgseende och känslighet för ljus?
A: Stavar: Hög känslighet för ljus, Tappar: Färgseende.

Q: Vilken hjärnstruktur tar emot input från näthinnan för att reglera dygnsrytm?
A: Suprachiasmatic nucleus

Q: Gällande hårcellernas funktion i cochlea, vilket påstående är inte korrekt?
A.
Det synaptiska maskineriet består av ribbons.
B.
Kaliumjoner (K^+ ) fyller en kritsik funktion i transduktionsprocessen.
C.
Hyperpolarisering uppstår när stereocilia böjs emot de längsta stereocilierna.
D.
Inre hårceller fyller en annan funktion än yttre hårceller.
E.
De är tonotopiskt organiserade längs basilarmembranet.
A: Hyperpolarisering uppstår när stereocilia böjs emot de längsta stereocilierna

Q: I däggdjurs cochlea, vad förskjuts av ljud med hög frekvens?
A.
Kaliumjoner (K^+ ) i perilymfan
B.
Helicotrema
C.
Otolitic membranet
D.
Runda fönstret
E.
Basilarmembranet vid cochleas apex.
A: Runda fönstret

Q: Vilken av följande regioner av hjärnan är inblandade i den vestibulo-okulär reflexen?
A: Abducens nucleus

Q: Vilken situation kan får hårcellerna i båggångarna att förändra sin membranpotential?
A: Somersaults (kullerbyttor, bakåtvolter)

Q: Vilket är korrekt gällande luktsinnen och lukt-transduktion
A.
Luktreceptorneuron har axoner direct kopplade till occipital (nack-) loben.
B.
Varje luktlob mottar synaptisk input från olika typer av luktreceptorneuron.
C.
Luktstimuli depolariserar primära luktreceptorneuron genom G-protein-kopplade receptorer i cilia hos receptorneuronerna.
D.
Mitral celler är neuroner som projeicerar på hypothalamus
E.
Signaleringen hos luktreceptorneuroner involverar cGMP.
A: Luktstimuli depolariserar primära luktreceptorneuron genom G-protein-kopplade receptorer i cilia hos receptorneuronerna.

Q: Vilken smak använder T2R/G-protein/PLCβ2/TRPM5 kanaler för signalering?
A: Bitter, umami

Q: Vilken mekanism kan förbättra kontrasten i sensoriska system?
A: Lateral hämning

Q: För att en beröringsstimulus ska nå din medvetna medvetenhet måste en specifik typ av neuron aktiveras. Vad kallas dessa neuron? I vilket område av hjärnan finns dess soma?
A: Third-order neuron; thalamus

Q: Vilken väg används för sensorisk information om beröring, vibration och proprioception?
A: Medial lemniscus

Q: Vilken opioidreceptor har störst påverkan när det gäller risken för andningsdepression?
A: δ (delta)-receptorer (DOPr) (?)

Q: Vilket av följande påståenden är felaktigt?
A.
Det finns vetenskapliga data om säkerhet avseende användning av komplementärmedicinska metoder, exempelvis manipulation och akupunktur, vid smärta.
B.
Kiropraktorer och naprapater är legitimerade yrkestitlar.
C.
Ett vanligt problem vid sammanställningen av forskning om komplementärmedicinska metoder är heterogenitet mellan studier och svårigheter med jämförande kontrollgrupper.
D.
Komplementärmedicinska metoder vid smärta används framför allt istället för konventionell hälso- och sjukvård, sk. alternativ användning.
E.
Majoriteten av användningen av komplementärmedicinska metoder vid smärta sker parallellt med konventionell behandling
A: Komplementärmedicinska metoder vid smärta används framför allt istället för konventionell hälso- och sjukvård, sk. alternativ användning.

Q: Hur mycket kan ögonen normalt ackommodera vid 40-45 års ålder?
A: >4 D

Q: En patient har fått en stroke som påverkat den posteriora temporalloben på höger sida. Vilket bortfall av syn skulle en sådan skada kunna leda till?
A: Övre vänstra fjärdedelen av synfältet

Q: Vad skulle en skada på den del av nervsystemet som är markerat på MRI bilden ge för symptom?
A: Nedsatt förmåga att känna vibrationer från vänster hand

Q: För vilket sinne är den markerade strukturen en viktig kärna?
A: Syn

Q: Vilket sinne har mest direkt kontakt med amygdala?
A: Lukt (men ksk fel för smak är mer rätt)

Q: För vilka sinnen spelar lobus insularis en stor roll?
A: Smärta och smak

Q: Vilken bana tar axon som förmedlar temperatur från thalamus till somatosensoriskakortex?
A: Capsula interna

Q: What do Ia fibers provide information about in the muscle spindle?
A: Ia have a rapidly adapring response, and therefore provide info about limb dynamics (changes in the muscle)

Q: What do II fibers provide information about in the muscle spindle?
A: II fibers have a sustained response, they are slow adapting and they provide infromation about the limb static postion, where ur body is located  in space

Q: "What is limb dynamics?"
A: Rapidly adapting response

Q: "What is limb static position?"
A: Sustained response

Q: Where are golgi tendon organ located?
A: In tendons

Q: What does golgi tendon organ inform about?
A: Informs about changes in muscle tension

Q: Which nerve endings are connected to golgi tendon organ?
A: Primary (Ib) nerve endings

Q: What do the dorsal column pathways do?
A: The pathways carry tactile information and proprioception to the brain

Q: What is another word for dorsla column?
A: Medial leminiscal pathway

Q: What are gracile tract/nucleus and cuneate tract/nucleus?
A: The axons of the 1st order neurons from the dorsal column

Q: What is the gracile tract/nucleus?
A: Pathways from the lower body

Q: What is the cuneate tract/nucleus?
A: Pathways from the upper body

Q: What happens with the axons from the gracile and cuneate tract/nucleus?
A: These axons go all the way up to the cordal medulla ipsilaterally on the same side of the body, but after the medulla there is a decussation a crossing of the axons of the 2nd order neurons crossing to the other side contralaterally - these axons form the medial lemniscus

Q: Which axons form the medial lemniscus?
A: The axons of 2nd order neurons that cross over (decussation) to the other side after the medulla kontralaterally

Q: Where is the decussation?
A: - After the medulla (body)
- In the pons: second order neurons in the principal nucleus of the trigeminal complex (face)

Q: What is VPM?
A: A nucleus of the face in the thalamus

Q: WHat is VPL?
A: A nucleus of the body in the thalamus

Q: What does VPL stand for?
A: Ventral posterior lateral nucleus

Q: What does VPM stand for?
A: Ventral Posterior Medial nucleus of thalamus

Q: What is SI?
A: Primary somatosensory cortex

Q: Where are 3rd order neurons located in the thalamus?
A: 3rd order neurons are located in the ventral posterior lateral part of the nucleus of the thamalmus (VPL) - thats for the body

Q: Where do 3rd order neurons project their axons?
A: 3rd order neurons project their axons to the primary somatosensory cortex (SI)

Q: How does info about proprioception go to SI?
A: For proprioception its about the same as form touch - the information goes to the kontralateral SI except that there are 4 main differneces

Q: What are the differences between how the info about proprioception goes to SI compared to touch?
A: 1 the first order neurons axons enter the spinal cord, they send collateras locally in the ventral horn -. These ventral axons are involved in triggering reflexes,
2one of the branches of the axons goes up and contacts a 2nd order neuron located in Clarke's nucleus, this is for the lower body - For touch and for the rest of the body there is no clarke's nucleus involved
3 the axons of the 2nd order neuron ascend to the cerebellum, this is the dorsal spinal cerebellar tract, the info for proprioception needs to reach the cerebellum since this pathway is involved in the control of movement
4th difference is for the face, proprioception of the cells - the cell bodies of the 1st order neurons are not in a ganglion but they are located here in the brainstem mesencephalon in the mesencephalic nucleus of the trigeminal nerve - this nucleus is involved in the control of jaw movement during feeding, mastication, the jaw reflex prevents us from biting too hard for ex.

Q: What are the differences between how the info about proprioception goes to SI when they enter the spinal cord compared to touch?
A: The
first order neurons axons enter the spinal cord, they send collateras locally
in the ventral horn -. These ventral axons are involved in triggering reflexes,

Q: What are the differences between how the info about proprioception goes to SI concrning clarke's nucleus compared to touch?
A: One
of the branches of the axons goes up and contacts a 2nd order neuron located in
Clarke's nucleus, this is for the lower body - For touch and for the rest of
the body there is no clarke's nucleus involved

Q: What are the differences between how the info about proprioception goes to SI concrning 2nd order neurons, compared to touch?
A: The
axons of the 2nd order neuron ascend to the cerebellum, this is the dorsal
spinal cerebellar tract - the info for proprioception needs to reach the
cerebellum since this pathway is involved in the control of movement

Q: What are the differences between how the info about proprioception goes to SI concerning the face, compared to touch?
A: 4th difference is for the face, proprioception of the cells - the cell bodies of the 1st order neurons are not in a ganglion but they are located here in the brainstem mesencephalon in the mesencephalic nucleus of the trigeminal nerve - this nucleus is involved in the control of jaw movement during feeding, mastication, the jaw reflex prevents us from biting too hard for ex.

Q: To where do we get proprioceptive information from the face?
A: The mesencephalic trigeminal nucleus in the midbrain