HNS Anatomy 4 - Oral Cavity and Upper GI Flashcards
What is the purpose of a GP asking you to open the mouth and say aaah?
- Tests the vagus nerve
- Soft palate should rise and the uvula will be in the midline.
- If its not working on one side the uvula will deviate towards the opposite side
List the components of the pharynx
- Nasopharynx
- Oropharynx
- Laryngopharynx
- Ends at the oesophagus
What happpens during swallowing?
- The larynx is raised
- This retroflexes the epiglottis to close the upper airway and prevent food getting through the trachea
What is the hard palette made of?
- Made of bone
- Allows food to be crushed against it
What is the piriform fossa?
- On either side of the larynx
- An area where bones can get caught, especially fish bones
- Requires forceps to remove
Describe the nerve supply of the tongue
- Sensory nerves for taste are anterior 2/3 facial (chorda tympani) and posterior 1/3 (glossopharyngeal)
- Sensory of the anterior 2/3 is the lingual branch of the trigeminal nerve
- Motor is vagus and hypoglossal
List the stages of swallowing
- Tongue is lifted and retracted by the styloglossus and intrinsic muslces
- Bolus then enters the oropharynx due to movement of the palatoglossus
- The nasopharynx is closed by raising the soft palate
- The larynx is raised and closed by the epiglotis
- Peristaltic wave of constrictor muscles (superior, middle and inferior)
- Cricopharyngeus muscle relaxes to allow passage of the food bolus
List the salivary glands and their innervation
- Parotid gland (produces largely serous thin salivary fluid, passage via the parotid duct opening in the upper second molar - Innervated by the glossopharyngeal nerve)
- Submandibular nerve (mainly serous - innervated by the facial nerve)
- Sublingual (mainly mucous - innervated by the facial nerve)
List the muscles of the tongue
- Styloglossus
- Hyoglossus
- Genioglossus
- Intrinsic muscles
What are the tongue muscles innervated by?
Hypoglossal nerve
What happens when the genioglossus muscle contracts?
- Protruding the tongue
- Used to test hypoglossal nerve function
- Tongue deviation will be towards the side of the lesion
List the functions of the lingual nerve
- Supplies the tongue with touch sensation
- Nerve fibres involved in taste sensation
Describe the taste innervation of the tongue
- Divided into anterior 2/3rds and posterior 1/3rd.
- Anterior sensation is the trigeminal nerve, and taste fibres are the facial nerve
- Posterior third is innervated by the glossopharyngeal nerve for both taste and sensation, with small amount of vagus supply
List the superficial muscles of mastication and their function
- Masseator (at the back of the mandible along zygomatic arch, elevates mandible and pops out when you force closure of the mouth)
- Temporalis (elevates and retracts the mandible)
- Buccinator muscle (pushes food towards the middle of the mouth, a muscle of facial expression)
How are muscles of mastication supplied?
All trigeminal (mandibular nerve) except the buccinator muscle, which is innervated by the facial nerve
List the deeper muscles of mastication
- Lateral pterygoid (sphenoid/lateral pterygoid plate to the neck of the mandible, depresses and protracts the mandible to open the mouth)
- Medial pterygoid (pterygoid plate/ maxilla to the angle of the mandible, elevates, protracts and lateral movement of mandible)
What is the function of the temporomandibular nerve?
- Jaw closed
- Slight depression of the jaw (hinge action)
- If you open widely there is a gliding movement up into the articular tubercle, as the capsular joint moves forward
- This can cause dislocation
What is done when the jaw dislocated?
- Push down and back on the back molars at the bottom of the mouth
- Put something in the mouth to prevent them biting
- This gets to the head of the mandible past the articular tubercle
List the branches of the external carotid artery
- Superior thyroid
- Ascending pharyngeal
- Lingual
- Facial
- Occipital
- Posterior auricular
- Maxillary
- Superficial temporal
Some anatomists like freaking out poor medical students
List the pathway of the internal carotid artery
- Forms at level of adams artery
- Carries on up through the base of the skull (carotid canal) to supply the anterior portion of the brain
- No branches
Describe the pathway of the maxillary artery
- Into the cheek artery
- Branches to the middle meningeal artery, which supplies the dura
- The middle meningeal artery enters the skull through the foramen spinosum
Describe the distribution of the facial nerve
- Exits the cranial cavity through the internal acoustic meatus, exiting through the stylomastoid foramen
- Passes underneath the parotid and branches, with five branches emerging from the anterior border of the parotid gland
- Chorda tympani
- Temporal branch most superiorly
- Zygomatic branch
- Buccal branch
- Mandibular branch
- Cervical branch (innervates the platysma muscle)
How is facial nerve function tested?
- Ask the patient to look up to the ceiling and look for creasing
List the branches of the V3 mandibular nerve and their pathway
- Passes down and exits though the foramen ovale
- Inferior alveolar nerve passes into the back of the mandible (sensory nerve for lower teeth)
- Terminal branch of the inferior alveolar nerve is the mental nerve (chin)
- The other main branch is the lingual nerve, which innervates the anterior 2/3 of the tongue .
- The lingual nerve also recieves fibres from the facial nerve, specifically the chorda tympani of the facial nerve, which goes through the petrotympanic fissure
- Parasympathetic outflow to the submandibular ganglion, and post ganglionic to the sublingual gland
Describe the dermatomes of the face
- V1, V2 and V3 of the trigeminal nerve
- V1 (opthalmic) supplies the forehead, nose and eyes
- V2 (maxillary) is the cheek, and between the nose and the lips
- V3 (mandibular) is the side of the face and below the lips
What is the significance of the meandering course of the facial artery?
Ensures the artery does not rupture following movement of the mandible
Which nerves supply the parasympathetic secretomotor innervation of the parotid gland?
Glossopharyngeal
Which nerve is sensory to the parotid gland?
Great auricular nerve
What is Bells palsy? How would it present in a patient?
- Bells palsy is damage to the facial nerve
- Results in drooping of the face as the muscles of the face cannot be moved
Which nerve supplies the pharyngeal constrictors?
Vagus nerve
Which nerves supply the digastric muscle?
- Anterior belly is supplied by the facial nerve
- Posterior belly is supplied by the trigeminal nerve (mandibular)
Which nerve supplies the myelohyoid muscle?
- Myelohyoid nerve
- A branch of the inferior alveolar nerve, which is a branch of the mandibular nerve (trigeminal
What is special about the mandibular branch of the trigeminal nerve?
- It is the only branch with both sensory AND motor funciton
- Supplies the temporalis, masseator, pterygoids, myelohyoid muscle and anterior belly of the digastric muscle)
List the movements of the mandible
- Protraction
- Retraction
- Elevation and depression
Compare a normal adult set of teeth to primary teeth
- Adult each side has 2 incisors, 1 canine, 2 premolar and 3 molar
- Deciduous set has 2 incisor, canine, 2 molars
What does the opthalmic division of the trigemnial nerve supply?
- Top of the head to the upper eyelids, and a strip down the median line of the nose
Supplies the conjunctiva that covers the inner surface of the eyelids - Supplies the nasal mucosa and frontal sinus
What does the maxillary division to the trigeminal nerve supply?
- Skin of the anterior temple and middle part of the face, as far down as the corners of the mouth
- Supplies the upper teeth, lip, gums and roof of the mouth
What does the mandibular division of the trigeminal nerve supply?
- Strip of skin running from the middle part of the temple then anteior to the ear and down to the chin
- Also supplies the lower teeth, gums and lip, lining of the cheeks, floor of the mouth and anterior 2/3 of the tongue
What supplies taste sensation of the tongue via the facial nerve?
- Chorda tympani
- Joins the lingual nerve, which is sensory (but not taste) to the tongue
How is the trigeminal nerve tested?
- Light touch in all 2 zones of the face either side
- Palpate masseator as the patient clenches their teeth
How is the facial nerve tested?
- Ask to look up at ceiling (frontalis)
- Keep eyes closed against resistance (orbicularis oculis)
- Bare their teeth (ristoris)
How is the glossopharyngeal nerve tested?
Gag reflex tested
How is the olfactory nerve tested?
Test smell with patients eyes closed
