vi. Oral Biology Flashcards
L40: What are the muscles of mastication?
The ‘mandibular muscles’:
- Masseter;
- Temporalis;
- Lateral Pterygoid;
- Medial Pterygoid.
L40: What is the origin, insertion and action of the masseter?
Origin: zygomatic arch
Insertion: lateral surface and angle of the mandible
Action: elevates mandible
L40: How do you examine the masseter?
- Tender in pts who have a clenching habit;
- Place one finger intra-orally and the other on the cheek;
- Is it sore, tender, inflamed?
L40: What is the origin, insertion and action of the temporalis?
Origin: floor of the temporal fossa
Insertion: coronoid process of the anterior border of ramus
Action: Elevates and retracts mandible
L40: How do you examine the temporalis?
- Tender in pts who have a clenching habit;
- Palpate its origin (can’t palpate insertion) by asking the pt to clench together;
- Is it sore, tender, inflamed?
L40: What is the origin, insertion and action of the lateral pterygoid?
Origin: from the lateral surface of the lateral pterygoid plate
Insertion: anterior border of the condyle and intra-articular disc (via two independent heads)
Function: protrudes and laterally deviates the mandible and the inferior head functions with the mandibular depressors during openings
L40: What are the insertions of each belly of the lateral pterygoid?
Inferior belly: head of the condyle;
Superior belly: intra-articular disc.
L40: What are typical symptoms of lateral pterygoid problems?
- Click on opening of mouth;
- Poor opening of mouth;
- Spasm due to exhaustion of muscle (overnight clenching).
L40: How are lateral pterygoid issues usually treated?
- Splint;
- Physiotherapy.
L40: The lateral pterygoid is not accessible to palpate so how is this examined?
- Best examines by recording the response to resisted movement (sideways);
- Palm on top of head and on mandible;
- Ask pt to move jaw sideways.
L40: What is the origin, insertion and action of the medial pterygoid?
Origin: medial surface of the lateral pterygoid plate (deep head), tuberosity of maxilla (superficial head)
Insertion: medial surface of angle of mandible
Action: elevates and assists in protrusion of the mandible
L40: Are you able to palpate/ examine the medial pterygoid?
No - due to its location and it doesn’t respond well to resistive movement tests (trismus)
L40: Following a LA injection, your pt is unable to open their mouth fully on the following day. Which muscle was hit by the LA?
Medial pterygoid
L40: When administering a LA, where should the needle contact and why?
The bone, to ensure the correct position within the pterygomandibular triangle (not the soft tissues)
L40: How many movements does the TMJ involve?
2
L40: What are the 2 movements of the TMJ?
- Rotation (initial opening);
- Translation (wider opening).
L40: What is the initial opening movement?
A hinge movement
L40: What is the secondary movement?
Translation, a sliding movement
for wider opening/ protrusive and retrusive movements
L40: Explain what happens when the mandible protrudes.
- Both condyles leave their fossae;
- Move forward along the articular eminences.
L40: Explain what happens when the mandible retrudes.
- Leave the eminences;
- Both condyles move back to their fossae;
L40: What is Posselt’s envelope?
A representation of maximum mandibular movement (from border movements of three different planes)
L40: What is the range of typical maximum biting force between molars?
200-700N (varies between teeth)
L40: What factors affect maximum biting force?
- Psychological: Fear of tooth fracture;
- Muscle mass: bigger muscles, larger forces;
- Tooth type and position: relative to TMJ, root area (PDL support).
L40: Why are greatest biting forces achieved between molars?
Closest to TMJ and muscles generating the forces, largest occlusal areas too
L40: What are the different muscle fibre types and what forces are they responsible for?
- Type I: slow, low forces;
- Type II (sub-types IIA, IIX, IIB): fast, stronger forces.
L40: What are the four supra hyoid (above hyoid bone) muscles?
- Digastric;
- Mylohyoid;
- Geniohyoid;
- Stylohyoid.
L40: What is a major function of supra hyoid muscles?
Jaw depressors
L40: What are the four infra hyoid (below hyoid bone/ ‘strap’) muscles?
- Sternohyoid;
- Omohyoid;
- Thyrohyoid;
- Sternothyroid.
L40: What do the infra hyoid bones do to ‘fix’ the hyoid bone in place?
Contract
L40: What do intrinsic tongue muscles do and what are their names?
- Alter shape;
- Longitudinal;
- Vertical;
- Transverse.
L40: What do extrinsic tongue muscles do and what are their names?
- Alter shape and position;
- Genioglossus;
- Hyoglossus;
- Palatoglossus;
- Styloglossus.
L40: Which facial muscles help to control a food bolus and prevent spillage?
- Orbicularis Oris;
- Buccinator.
L47: What are the three branches of the trigeminal nerve?
- Ophthalmic;
- Maxillary;
- Mandibular.
L47: Which cranial nerve is the trigeminal nerve?
Cranial nerve five (V)
L47: What are the 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
L47: Which branch of the mandibular branch, of the trigeminal nerve, innervates the front of the chin and lower lip?
Mental nerve
L47: Where does the mental nerve exit the mandible?
Mental foramen
L47: What is paraesthesia?
An abnormal sensation, typically tingling or prickling
L47: What is dyaesthesia and what causes it?
An abnormal, unpleasant sensation felt when touched due to damage to peripheral nerves
L47: What is the afferent (sensory) supply of the gag reflex?
IX, glossopharyngeal
L47: What is the efferent (motor) supply of the gag reflex?
V: Jaw opening
X: Pharyngeal constriction
XII: Tongue thrust
IX and XI also
L47: With regards to RPDs, what method can be used to prevent the patient’s gag reflex during its use?
Use of a metallic mesh attachment to the base, instead of a post-dam ridge
L47: What is Bell’s Palsy?
Temporary facial paralysis to one side of the face
L47: What are the common causes for Bell’s palsy?
- Infection;
- Otitis Media;
- Diabetes;
- Trauma;
- Toxins;
- Infiltration of LA during dental tx.
L47: What are the common symptoms for Bell’s Palsy?
- Asymmetrical;
- Inability to wrinkle brow;
- Drooping eyelid;
- Inability to puff cheeks;
- Drooping mouth.
L47: How can LA in dental tx cause Bell’s Palsy?
When the injection is given too far distally, the LA penetrates the parotid gland, then diffuses to the facial nerve and effects all five branches
L47: What should you do if your patient develops Bell’s Palsy as a result of your tx?
- Reassure them it is temporary;
- Protect their eye with a loose pad to protect the cornea until blinking returns.
L47: Which cranial nerve is the facial nerve?
Cranial nerve seven (VII)
L47: What are the five branches of the facial nerve?
- Temporal (two);
- Zygomatic (zulus);
- Buccal (bugged);
- Mandibular (my);
- Cervical (cats).
L47: What is the benefit or retaining natural tooth roots or stumps with RPD tx?
- For periodontal mechanoreceptors: a better appreciation of food/ more precise mandibular movement;
- Psychological benefit: retaining own teeth;
- Gradual transition to a complete denture.
L47: What is the lowest threshold for mechanoreceptors?
0.5mN
L47: What functions do periodontal mechanoreceptors contribute to?
- Direction of applied forces to teeth;
- Mastication (food consistency);
- Salivation;
- Interdental discrimination.
L47: What receptors (location) contribute to interdental size discrimination?
- TMJ;
- Muscles;
- PDL.
L47: What is proprioception?
Awareness of position and orientation of body parts
L47: What proprioceptors contribute to proprioception?
- Joint;
- Muscle;
- PDL.
L47: What is dysphagia?
Difficulty swallowing
L47: What can cause dysphagia?
- Stroke;
- Brain injury;
- MS;
- GORD;
- Tumours.
L47: What are nociceptors?
Receptors that detect intense stimuli, usually associated with pain
L47: What is the medical term for a loss of smell?
Anosmia
L47: Why can anosmia effect sense of taste?
Smell and taste are strongly interlinked because the sense of smell stimulates salivary glands and saliva contributes to the initial breakdown of food, which you taste
