Head And Neck Week 9

Question 1

What are the functions of the oral cavity?

Answer 1

Digestion - receives food and prepares it for digestion
Communication - modifies the sound produced int he larynx to create a range of sounds
Breathings - air inlet in addition to nasal cavity

Question 2

How can the oral cavity be divided?

Answer 2

Into two parts:
Oral vestibule - slit like space between the teeth and gingivae and the lips and cheeks
Oral cavity proper - space between upper and lower dental arches or arcades (maxillary and mandibular alveolar arches and the teeth they bear) - limited anteriorly and laterally by the dental arches

Question 3

Describe the oral fissure

Answer 3

Opening of the oral cavity to the exterior
Size controlled by peri-oral muscles - orbicularis oris, buccinator, risorius, and depressors and elevators of the lips (dilators of the fissure)

Question 4

What fully occupies the oral cavity when the mouth is closed and at rest?

Answer 4

The tongue

Question 5

What are the boundaries of the oral cavity?

Answer 5

Roof - formed by the palate - hard palate covered inferiorly by oral mucosa (stratified squamous epithelium) - soft palate muscle that can lower to close the oropharyngeal isthmus and elevate to separate the nasopharynx and oropharnyx
Posterior - communicates with the oropharynx at the oropharyngeal isthmus
Floor : - Muscular diaphragm - comprised of the bilateral mylohyoid muscles. It provides structural support to the floor of the mouth, and pulls the larynx forward during swallowing.
- Geniohyoid muscles – pull the larynx forward during swallowing.
- Tongue – connected to the floor by the frenulum of the tongue, a fold of oral mucosa.
- Salivary glands and ducts
Lateral - The cheeks - formed by the buccinator muscle, which is lined internally by the oral mucous membrane.
The buccinator muscle contracts to keep food between the teeth when chewing, and is innervated by the buccal branch of the facial nerve (CN VII).
Anterior - oral fissure

Question 6

Describe the oral vestibule

Answer 6

The horseshoe-shaped vestibule is situated anteriorly. It is the space between the lips/cheeks, and the gums/teeth.

The vestibule communicates with the mouth proper via the space behind the third molar tooth, and with the exterior through the oral fissure. The diameter of the oral fissure is controlled by the muscles of facial expression – principally the orbicularis oris.

Opposite the upper second molar tooth, the duct of the parotid gland opens out into the vestibule, secreting salivatory juices.

Question 7

What structures make up the oropharyngeal isthmus?

Answer 7

Palatopharyngeal arch, uvula and tip of the epiglottis

Question 8

What are alternative names for the palatopharyngeal arch and the palatoglossal arch?

Answer 8

Posterior and anterior arch, respectively

Question 9

Which bones form the hard palate?

Answer 9

Maxilla

Palatine bones

Question 10

Describe the muscles of the soft palate

Answer 10

Tensor veli palatini - medial pterygoid nerve (CNV3) - tenses soft palate and opens mouth of pharyngotympanic tube during swallowing and yawning
Levator veli palatini - Pharyngeal branch of vagus - elevates soft palate during swallowing and yawning
Palatoglossus - Pharyngeal branch of vagus - elevates posterior part of tongue and draws soft palate onto tongue - forms anterior arch
Palatopharyngeus - Pharyngeal branch of vagus - tenses soft palate and pulls walls of pharynx superiorly, anteriorly and medially during swallowing - forms posterior arch
Muscular uvulae - Pharyngeal branch of vagus - Shortens uvula and pulls superiorly

Question 11

Which way does the uvula deviate in a pharyngeal branch (CN X) lesion?

Answer 11

Away from the affected side (unopposed muscles pulling it)

Question 12

Describe the gag reflex

Answer 12

Afferent limb - Glossopharyngeal - back of tongue/throat, uvula, tonsillar area
Efferent limb - Vagus - pharyngeal muscles of soft palate

Question 13

Draw and label a diagram of the teeth

Answer 13

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Question 14

Why can you sometimes get a numb tongue during dental procedures?

Answer 14

Close relationship between the inferior alveolar and the lingual nerve

Question 15

Describe the sensory supply of the lower jaw

Answer 15

Inferior alveolar nerve (branch of CN V3)
Can lose sensation during a mandibular fracture
Used as the site of anaesthesia in dental procedures

Question 16

What are the extrinsic muscles of the tongue?

Answer 16

Genioglossus
Styloglossus
Hyoglossus
Palatoglossus

Question 17

Where do the extrinsic muscles of the tongue attach?

Answer 17

Hyoid bone and mandible

Question 18

What are the functions of the extrinsic tongue muscles?

Answer 18

Allow the tongue to change position

Anchor

Question 19

What is the innervation of the tongue muscles?

Answer 19

Hypoglossal nerve except palatoglossus which is innervated by the vagus

Question 20

What are the intrinsic muscles of the tongue and what are their actions?

Answer 20

Superior longitudinal - curling
Inferior longitudinal - curling
Vertical - flatten
Transverse - pull in/make thinner

Question 21

What is the sensory innervation of the tongue?

Answer 21

Anterior 2/3:
General - lingual nerve (CN V3)
Special - chorda tympani (CN VII)

Posterior 2/3:
General and special - glossopharyngeal nerve (CN IX)
General - Internal laryngeal nerve (CN X)

Question 22

Which way does the tongue deviate in a unilateral lesion of the hypoglossal nerve?

Answer 22

Towards the side of the lesion

Normal tongue muscle pushes harder than the affected side, overpowering it

Question 23

Through what openings do the salivary glands open?

Answer 23

Parotid gland and duct - Stenson’s duct
Submandibular gland and duct - Wharton’s duct
Sublingual gland opens via multiple duct

Question 24

What are salivary gland stones and which duct do they most commonly affect?

Answer 24

Saliva crystallises and blocks the salivary ducts - usually calcium based
Unknown aetiology
Most commonly affects the submandibular duct - saliva produced is comparatively thicker than other glands
Sublingual stones very rare

Question 25

What are the signs and symptoms of salivary gland stones?

Answer 25

Pain or swelling of the gland at meal times | May be able to see wharton's duct stone

Question 26

How are salivary gland stones managed?

Answer 26

Small stones may resolve spontaneously | Commonly need removal

Question 27

Which tonsils are usually affected by tonsillitis, how do patients present and what is the common pathogen?

Answer 27

Palatine tonsils Odynaphagia or dysphagia - tonsils enlarged and erythematous Usually infective - viral - rhinovirus, adenovirus - symptoms of URTI (cough) Bacterial - beta haemolytic strep - cervical lymphadenopathy, fever, pus

Question 28

How do you decide whether the tonsillitis is bacterial or viral?

Answer 28

Centor criteria | Fever/Pain score

Question 29

What is a peritonsillar abscess/ Quinsy, what causes it, how does the patient present and what is the management?

Answer 29

Severe complication of bacterial tonsillitis - usually strep pyogenes, can be staph aureus, H.infleunza or mixed flora Typically systemically unwell with trismus and "hot potato voice" (painful jaw upon opening), drooling due to dysphagia Unilateral - uvula deviates away from lesion Immediate referral to ENT

Question 30

What kind of joint is the temperomandibular joint?

Answer 30

Modified hinge synovial joint between the cranium and the mandible

Question 31

Which structures articulate at the TMJ?

Answer 31

Condyle of the mandible Articular tubercle of the temporal bone Mandibular fossa of the temporal bone

Question 32

What divides the TMJ into superior and inferior compartments?

Answer 32

Articular disk

Question 33

Describe the properties of the TMJ joint capsule

Answer 33

Relatively loose - mobility>stability

Question 34

Which ligaments support the TMJ ?

Answer 34

Lateral ligament (temperomandibular ligament) Stylomandibular ligament Sphenomandibular ligament

Question 35

Describe the movements of the TMJ and the muscles that produce them

Answer 35

Elevation - temporal, masseter and medial pterygoid Depression - lateral pterygoid, super/infrahyoid, gravity Protrusion - lateral pterygoid mainly Retrusion - temporal Lateral movements (e.g. Chewing) - temporal on same side, lateral pterygoid of opposite side and masseter on same side

Question 36

What is the innervation of the muscles of the TMJ?

Answer 36

Muscles of mastication - temporalis, masseter, pterygoids - mandibular branch of trigeminal nerve (CN V3) - auriculotemporal nerve

Question 37

How can TMJ dislocation occur, and what are complications?

Answer 37

During yawning, taking a large bite - excessive contraction of the lateral pterygoids may cause the heads of the mandible to dislocate anteriorly - mandible remains depressed and the person is unable to close his or her mouth - lock jaw A sideways blow to the chin of an open mouth by a fist - dislocates the mandible on the side that received the blow May accompany fractures of the mandible Posterior dislocation uncommon due to postglenoid tubercle and the strong intrinsic lateral ligament In falls or direct blows to the chin the neck of the mandible fractures before dislocation occurs (usually) Care must be taken during surgery - to preserve both branches of the facial nerve overlying it and the auriculotemporal nerve Injury to articular branches of auriculotemporal nerve supplying the TMJ - in traumatic dislocation, rupture of the articular capsule and lateral ligament --> laxity and instability of the TMJ

Question 38

In a suspected TMJ dislocation, what else should be checked for?

Answer 38

Fracture to the opposite side of the jaw

Question 39

What are the differential diagnoses for TMJ pain?

Answer 39

Temporal arteritis - type of vasculitis (serious - can go blind) Bruxism- teeth grinding Osteoarthritis of TMJ Inter-articular disk derangement (younger age - can normally operate) Pathophysiology poorly understood Multifactoral causes - anatomical, psychological and social - anxiety, alcohol, smoking, sleep disorders

Question 40

Describe the borders of the infratemporal fossa

Answer 40

Laterally: Ramus of the mandible Medially: Lateral pterygoid plate Anteriorly: Posterior aspect of the maxilla Posteriorly: Tympanic plate and the mastoid and styloid processes of the temporal bone Superiorly: the inferior (infratemporal) surface of the greater wing of the sphenoid Inferiorly: Where the medial pterygoid muscle attaches to the mandible near its angle

Question 41

What is the infratemporal fossa?

Answer 41

An irregularly shaped space deep and inferior to the zygomatic arch, deep to the ramus of the mandible and posterior to the maxilla Communicates with the temporal fossa through the interval between (deep to) the zygomatic arch and (superficial to) the cranial bones

Question 42

Describe the contents of the infratemporal fossa

Answer 42

``` Inferior part of the temporalis muscle Lateral and medial pterygoid muscles Maxillary artery Pterygoid venous plexus Mandibular, inferior alveolar, lingual, buccal and chorda tympani nerves Otic ganglion ```

Question 43

Where do the nerves of the infratemporal fossa branch from?

Answer 43

Mandibular branch - inferior alveolar nerve (continues as mental nerve), lingual (chorda tympani and general sensory to anterior 2/3), buccal (sensory to cheek and buccal gum) Otic ganglion - parasympathetic supply to parotid gland

Question 44

What is the clinical relevance of the infratemporal fossa?

Answer 44

Isolated infections e.g. Diabetic patients Tumours (rarely) Infection --> cavernous sinus thrombosis due to communication with pterygoid venous plexus Can be used as site for mandibular nerve block

Question 45

What are neural crest cells?

Answer 45

A specialised subpopulation of cells that originates within the lateral border of the neuroectoderm and migrates throughout the mesoderm Contribute to a variety of H+N structures Fourth germ lineage

Question 46

What are the main features of the face?

Answer 46

Palpebral fissures Oral fissure Nares Philtrum

Question 47

What is the embryological origin of the facial skeleton?

Answer 47

Neural crest of 1st pharyngeal arch

Question 48

What is the embryological origin of the muscles of mastication?

Answer 48

Mesoderm of 1st pharyngeal arch

Question 49

What is the embryological origin of the muscles of facial expression?

Answer 49

Mesoderm of 2nd pharyngeal arch

Question 50

What structures constitute the facial primordia?

Answer 50

1st pharyngeal arch: - maxillary prominence - mandibular prominence Frontonasal prominence: - surrounds ventrolateral part of the forebrain - primordia of eyes Stomatodeum - buccopharyngeal membrane - no mesoderm between endoderm and ectoderm

Question 51

What facial features develop from the frontonasal prominence?

Answer 51

FNP: - forehead - bridge of the nose - nose - philtrum

Question 52

What facial features develop from the maxillary prominence?

Answer 52

Maxillary: - cheeks - lateral upper lips - lateral upper jaw

Question 53

What facial features develop from the mandibular prominence?

Answer 53

Mandibular: | - lower lip and jaw

Question 54

Describe the development of the nose and palate

Answer 54

Nasal placodes develop on the frontonasal prominence Sink to become nasal pits Medial and lateral nasal prominences form on either side of the pits - oronasal membrane initially forms between the nasal pit and oral cavity but then quickly ruptures Maxillary prominences grow medially, pushing the nasal prominences closer together in the midline Maxillary prominences fuse with medial nasal prominences Medial nasal prominences fuse in the midline - forms the intermaxillary segment : - labial component: philtrum - upper jaw: 4 incisors - palate: primary palate Main part of definitive palate is secondary palate - derived from palatal shelves which develop from the maxillary prominence - grow vertically downwards into oral cavity on each side of the developing tongue Mandible grows large enough to allow the tongue to drop Palatal shelves grow towards each other and fuse in the midline Nasal septum develops as a midline down-growth and ultimately fuses with the palatal shelves

Question 55

Describe some developmental conditions involving the nose, lip and palate and the clinical consequences

Answer 55

Lateral cleft lip - failure of fusion of medial nasal prominence and maxillary prominence - can involve the primary palate Cleft lip and cleft palate - failure of fusion of medial nasal prominence and maxillary prominence combined with failure of fusion of the palatal shelves at the midline - lip, primary and secondary palate involved Difficulty with suckling - needs to be treated ASAP Difficulty with speech development

Question 56

Summarise the fates of the prominences

Answer 56

Frontonasal - forehead, bridge of nose, medial and lateral nasal prominences Medial nasal - philtrum, primary palate, mid upper jaw Lateral nasal - sides of nose Maxillary - cheeks, lateral upper lip, secondary palate, lateral upper jaw Mandibular - lower jaw and lip

Question 57

Describe the development of the eyes

Answer 57

Development begins in week 4 Out-pocketing of forebrain - optic vesicle Grow out to make contact with overlying ectoderm- Optic placodes - lens Optic placode invaginates and pinches off Retina - develops from optic vesicle (diencephalon/forebrain) Optic nerve - transformed optic stalk Eyes are initially on the sides of the head but move to the front as the prominences grow - binocular vision

Question 58

Describe the development of the ears

Answer 58

External auditory meatus develops from 1st pharyngeal cleft (only cleft that remains) Auricles develop from proliferation within the 1st and 2nd pharyngeal arches surrounding the meatus Initially develop below the mandible (in the neck) As the mandible grows the ears ascend to the side of the head to lie in line with the eyes All common chromosomal abnormalities have associated external ear anomalies Otic vesicles - 22 days - thickening of the surface of ectoderm on each side of the rhomboencephalon - invaginate rapidly and form the otic/auditory vesicles (otocysts) - cells from here differentiate to form ganglion cells for the vestibulocochlear ganglia - later each vesicle divides into a ventral component that gives rise to the saccule and cochlear duct and a dorsal component that forms the utricle, semicircular canals and endolymphatic duct - together these epithelial structures form the membranous labyrinth

Question 59

What is foetal alcohol syndrome and alcohol related neurological disorder?

Answer 59

Association between maternal alcohol ingestion and congenital abnormalities - may induce a broad spectrum of defects, ranging from intellectual disability to structural abnormalities of teh brain, face and heart FAS - severe end of the spectrum - indicates structural defects, growth deficiency and intellectual disability ARND - cases with evidence of involvement of the CNS that do not meet the criteria for FAS Together incidence estimated at 1 in 100 live births No safe levels of alcohol during pregnancy - but dose and timing during gestation are both critical Neural crest migration and brain development extremely sensitive to alcohol No barrier to alcohol crossing the placenta

Question 60

What is a placode?

Answer 60

Area of ectoderm that starts to thicken and differentiate itself from the surrounding tissue to give rise to sensory structures

Question 61

When can cleft lip and palate be diagnosed and what is the incidence?

Answer 61

20 week scan or after birth | 1 in 700 babies born - most common facial birth defect in UK