Sensory, Motor Systems and Senses Flashcards
what is the sensory nerve involved in innervating the lower molars?
Mandibular branch of Trigeminal Nerve
CNV3
what are the 3 branches of the trigeminal nerve
mandibular
maxillary
opthalimic
12 Cranial Nerves
I: Olfactory II: Optic III: Oculomotor IV: Trochlear V: Trigeminal VI: Abducens VII: Facial VIII: Vestibulocochlear IX: Glossopharyngeal X: Vagus XI: Accessory XII: Hypoglossal
The sensory branch of the Inferior alveolar nerve which supplies the chin and lower lip is called?
MENTAL – comes from mental foramen to supply chin soft tissue
where does the mental nerve of the inferior alveolar nerve exit
exits the mandible via the mental foramen (supplying sensory branches to the chin and lower lip).
what nerve is effected by ID block
inferior alveolar dental nerve
where does the ID block numb to
the midline of mandible
basics of ID block (cover more later)
- Target – mandibular sulcus superior to mandibular foramen
- Greatest depression on coronoid notch determines height and angle of injection
- Advanced from contralateral premolar region
- Bone contact then retract slightly
- Both patient and dentist need PPE – eye protection
- Inferior alveolar nerve and lingual nerve are close together – withdraw slightly can anesthetize lingual nerve too
where does the needle hit in ID block
Needle is not hitting the nerve
Deposit LA next to nerve on the bone
- Feel bone before inject – if feel soft then don’t inject
paraesthesia
an abnormal sensation, typically tingling or pricking (pins and needles)
dysaesthesia
an abnormal unpleasant sensation felt when touched, caused by damage to peripheral nerves.
why is Paresthesia/dysesthesia a good sign
good sign not complete anesthesia
- Can be reversed definitely therefore Good if develop it
why may numbness remain?
due to temporary trauma/damage of the ID nerve
- Can ulcerate lip as don’t feel it – more prone to biting it
Will eventually go away, oedema on nerve but no completely dissection on nerve so will reverse
What mechanisms are involved in the gag response?
just mechanical
what does the gag reflex do?
Acts to prevent material entering pharynx
what evokes the gag reflex
Evoked by mechanical stimulation or fauces, palate, posterior tongue, pharynx
Some patients gag when instruments and/or materials are placed in the mouth
what nerves are involved in gag reflex
Efferent (motor) response from V, IX, X, XI and XII
- Trigeminal, Glossopharyngeal, Vagus, Accessory, Hypoglossal
The motor (secretory) visceral nerves of salivary glands are also stimulated
afferent neurons
sensory
these carry a message into the CNS. They are going toward the brain or spinal cord.
efferent neurone
motor
these carry a message to a muscle, gland, or other effector. They are said to carry the message away from the CNS
interneuorn
connecting neuron
these neurons connect one neuron with another. so multiple in many reflexes, interneurons connect the sensory neurons with the motor neurons.
how can a RPD be made to manage gagging reflex (3)
The posterior part of this RPD is constructed with a retaining mesh to facilitate the attachment of acrylic extension.
- design is indicated when the post-dam cannot be tolerated by the patient (gagging reflex), allowing it to be adjusted more easily.
- this approach will reduce the weight of a large metal connector.
Mesh covered in acrylic – can reduce it (complete mesh cannot reduce so give availability of reduction)
Magnets
- For retention instead of maximal coverage
- Or shortened post-dam area
Compromise retention but otherwise may not be able to wear
examples of gagging control mechanisms for when taking impressions
Not too runny, not tolerated by patient (may make thicker)
Hot water faster setting
Select fast set alginate brand
Patient chin down
Come from back of patient not from front like usual lower impression – rotation movement
Breathe from the nose – distract the patient
Patient attends the practice, he is clearly upset and you notice he is holding a wet white hankie to his face with his right hand. He states that ‘food keeps getting stuck in my cheeks’ As you investigate further the patient tells you that he had a bad ear infection last week
what may explain this?
Related to motor nerve not sensory
- Related to facial nerve
Damage to facial nerve (CNVII) – bell’s palsy
- Injected facial nerve distally in parotid – inject one of the 5 branches
Ear infection – swelling pushes on facial nerve
Effects function of orbicularis oris and buccinator – food bolus no longer in centre of oral cavity
White hankie is telltale sign of facial paralysis
- Cannot control saliva as lost muscle control
Bells
what types of disorder is Bell’s Palsy?
motor
facial nerve branches (5)
- Temporal
- Zygomatic
- Buccal
- Mandibular
- Cervical
To Zanzibar By Motor Car
Related to Bell’s Palsy symptoms
what key muscles are innervated by the facial nerve
buccinator and orbicularis oris
facial nerve number
CNVII
role of buccinator and orbicularis oris
Help control food bolus and prevent spillage
Bell’s Palsy definition
for any type of facial paralysis that does not have any other associated causes such as tumors, trauma and salivary gland inflammation
- No other associated causes –cannot explain cause of paralysis directly
Symptoms and signs of Bell’s Palsy (4)
Inability to wrinkle brow
Drooping eyelid; inability to close eye
Inability to puff cheeks; no muscle tone
Drooping mouth; food stuck in cheek
Bell’s Palsy Causes (6)
Infections (HSV/ Cold sores)
Otitis Media (inflammation of the middle ear)
Diabetes
Trauma
Toxins
Temporarily by infiltration of LA to the facial nerve branches during dental treatment
- Caused by dentist
how can a dentist cause Bell’s Palsy
Temporarily by infiltration of LA to the facial nerve branches during dental treatment
occurs when the LA injection is given too far distally and the parotid gland is penetrated, allowing the diffusion of the LA through loose glandular tissue, which then affects all five terminal branches of the facial nerve.
- Parotid gland by posterior border of mandible
what is a complication of ID block
Facial Nerve Paralysis (Palsy)
how can you see a facial nerve paralysis (Palsy)
The effect is seen in inability to close the eye or blink, and inability to raise the corner of mouth or puff the cheeks.
- Patients may feel that something is wrong but be unable to identify exactly what the problem is, and it is usually the operator who notices these specific changes.
- Patient may not feel it or notice but clinical assessment can notice
is facial nerve paralysis (palsy) reversible
yes
should wear off with LA
management of facial nerve paralysis (palsy)
patients should be informed, reassured as to the transitory nature of the palsy, a
the eye should be protected with a loose pad such that the cornea is protected until the protective blink reflex returns.
- Need to protect eye from being dehydrated and cornea being damaged
Your next patient for the day, a retired worker who was present to you seeking replacement of ill-fitting lower partial denture. On examination, there was only 2 remaining over erupted lower canines holding the denture in place. Although your patient was seeking extraction of these 2 teeth and receiving a new set of complete dentures
What would you offer your patient as treatment options?
Canines – strong last teeth to be extracted
- over-denture maintaining periodontal mechanoreceptors
Porcelain most aesthetic, economical but don’t use in upper denture with lower implant because very fragile and can fracture – low shearing force resistance
Implants not as appropriate as likely lost all arch
what do periodontal mechanoreceptors allow
allow finer discrimination of food texture, tooth contacts and levels of functional loading.
what are periodontal mechanoreceptors
the roots and their periodontal ligaments remain,
Decoronated the tooth (remove the crown but leave roots)
Have PDL so have proprioception – forces on areas, feel bolus
advantages of periodontal mechanoreceptors (5)
A better appreciation of food and a more precise control of mandibular movements than is provided by full dentures.
- More natural feeling than full denture, more acceptable
Maintain shape
Psychological benefit by preventing the feeling of total loss of natural teeth.
Makes eventual transition to conventional complete dentures more acceptable
Can place precision attachment
- Reduce number of clasps – retention from studs and clasps
precision attachment of RPD
Reduce number of clasps – retention from studs and clasps
what are the consequences of a failed implant
Expensive, time consuming
No PDL nothing to tell patient about occlusal forces in mouth – no mechanoreceptors
- Eat something hard – open mouth as protective mechanism
Not available in artificial root
the loss of periodontal mechanoreceptors influences
- the control of jaw function
- the precision of magnitude
- direction
- rate of occlusal load application.
general touch sense from
mechanoreceptors
mechanoreceptors are
sensory receptors that responds to mechanical pressure or distortion
properties of mechanoreceptors
- Low thresholds (0.5mN)
- Adaptation to constant stimulus
- Slowly & rapidly adapting types
periodontal mechanoreceptors enable
us to assess the direction of forces applied to teeth
- very sensitive
what 3 oral functions do periodontal mechanoreceptors contribute to
- Mastication (food consistency)
- Salivation
- Interdental discrimination
interdental discrimination is
Ability to gauge extent of mouth opening
interdental discrimination is used for
- Coordination of masticatory movements
- Monitoring size of food particles
- Detection of ‘high’ spots
(Foil thresholds 8-60μm; Articulating paper is 40μm or less; Shimstock (metal foil for occlusal testing) is the thinnest at 8μm)
3 receptors that contribute to interdental discrimination
- TM joint receptors
- Muscle receptors
- PDL receptors
what is proprioception
‘Self’ sense
Awareness of position and orientation of body parts
what are 3 proprioceptors
Joint receptors
Muscle receptors
- muscle spindles
- Golgi tendon organs
Periodontal receptors
what may joint receptors of proprioception signal
- joint position (mouth open, closed)
- joint movement (opening, closing)
what is joint receptors of proprioception information used for
Information useful in controlling jaw movements, e.g. chewing
consequence of loss of periodontal mechanoreceptors incomplete dentures
do not carry enough sensory information to restore the necessary natural feedback pathways for motor function.
- they are inherently unstable during normal functional jaw movements.
what 5 disorders can lead to dysphagia
- stroke can be first sign
- brain injury
- multiple sclerosis
- gastroesophageal reflux disorder
- tumours
also medicine can effect salivary glands
if patient complains fo food getting stuck in their throat what must you first do
most likely differential diagnosis
- exclude stroke first
how to assess if a stroke has occurred
Comparing sensorial and motor responses from both sides of face and oropharynx can easily detect stroke
- Stroke is unilateral
Touch areas and compare with other side (one effected and one not)
Minor strokes proceed major stroke, diagnose early to help save
FAST actions to assess a stroke
facial weakness,
arm weakness,
speech problems,
time to call 999
nociceptors
Respond to intense (noxious) stimuli, that are usually associated with pain
Nociceptors in the dental pulp are the most important ones for dentists
- Pulpitis and toothache
sensitivity of oro-facial tissue
very sensitive
receptors have low thresholds for activation
- but not all regions are equally sensitive
How can you tell that the sweet in your mouth is a mint with a hole in it without looking at it?
- Taste buds and olfaction of mint
- Will also have the experience of tasting a polo which will facilitate correlation
- Acquire the format of the mint by compressing it against the hard palate with the tongue
- Mechanoreceptors will be able to identify the format since the 2 point discrimination of both tissues allows that identification
how are smell and taste related
sense of smell stimulates salivary glands.
how can smelling disorders effect taste
sense of small stimulated salivary glands (related)]
In cases of infection of nasopharynx, a loss of olfactory sense (Anosmia) might be associated.
how can a denture effect taste?
cover palate lose 2 point discrimination (need palatal coverage for support)
- Effects texture and therefore taste
Horseshoe or ring shaped or anterior and posterior strapped dentures better as palate exposed
senses involved in wine tasting
Olfactory – sense of smell stimulates salivary glands
Sight
Texture – thickness/viscosity of liquid
Temperature and thermorecptors
It is 9am and you first patient, who had a wisdom tooth surgically extracted under LA a week ago, attends complaining that his lower lip is still numb. You examine the area and notice that the patient has been biting his lip and there is still ulceration in the area
Can you provide an explanation as to what had happened?
Traumatised inferior alveolar dental nerve when delivering LA
- From trigeminal mandibular, sensory and motor
Trauma from needle hitting not chemical
- Didn’t completely dissect nerve just traumatised (dissect potential on extraction)
Reversible damage (return to normal feeling eventually)
Due to numbness patient will have lack of awareness of their bite force – causing ulceration over repeated bite
- Absence of sensation
Not hit mental branch of mandibular nerve (last branch stemming from main nerve, by mental foramen
Plan to take an impression to prepare a new denture for your 10am. As you select a suitable tray, you recall patient is prone to gagging every time you place a tray in their mouth. What mechanisms are involved in the gag response?
Mechanical
- Fauces, palate, posterior tongue, pharynx
Reflex – prevent material entering pharynx
- Hit receptors that trigger CN9
nerves involved
- Efferent (motor) response from V, IX, X, XI and XII
(Trigeminal, Glossopharyngeal, Vagus, Accessory, Hypoglossal
- The motor (secretory) visceral nerves of salivary glands are also stimulated
11am patient arrives to tell you that she has a ‘stinking cold’ and that her nose is ‘bunged up’ and complains she has lost her taste. Can you provide an explanation for her complaint?
Smell related to taste – because smell stimulates salivary glands
- lose sense of smell = lose sense of taste
can mix up smell and taste – subjective to patient
- taste can also be related to texture
