HNS29 Oral Cavity, Submandibular And Sublingual Glands

Question 1

Oral cavity bony framework

Answer 1

1. Maxilla
2. Palatine bone (hard palate)
3. Mandible

Maxilla, Mandible: with alveolar process for teeth attachment

Question 2

Oral cavity boundaries

Answer 2

1. Roof:
   - Hard palate (soft palate is in pharynx)
2. Floor:
   - Mylohyoid muscle (attach between mandible and hyoid)
3. Side walls:
   - Buccinator muscle (CN7)
   —> superior attachment: Maxilla (alveolar process)
   —> **Pterygomaxillary ligament (extend from **Maxillary tuberosity to **Hamulus of medial pterygoid plate)
   —> extend downward
   —> **Pterygomandibular raphe (interdigitate with superior constrictor of pharynx, behind 3rd molar of mandible)
   —> **links Pterygoid process to Mandible
   —> insert into superior to posterior end of **Mylohyoid line
   —> muscle continue to form **External oblique line of Mandible (up to 1st lower molar)
   —> anterior fuse with **Orbicularis oris muscle
4. Anterior:
   - Oral fissure
5. Posterior:
   - Oropharynx
   - separated from oropharynx by Anterior pillar of fauces (Palatoglossal arch)

Oropharyngeal fauces: bounded by Anterior pillar + Posterior pillar (Palatopharyngeal arch)

Question 3

Oral cavity division

Answer 3

1. Oral cavity proper
   - space medial / posterior to teeth
2. Vestibule
   - space between teeth/gum and cheek
   - parotid duct opening is next to second upper molar each side

Question 4

Sensory supply of oral cavity

Answer 4

CNV2

• Roof (Hard palate): Greater palatine nerve (posterior) + Nasopalatine nerve (anterior)
• Upper teeth: Superior alveolar nerve

CNV3

• Floor: Lingual nerve
• Cheek: Buccal nerve
• Lower teeth, chin: Inferior alveolar nerve

(Oropharynx: Pharyngeal plexus (CN9,10))

Question 5

Hard palate bone components

Answer 5

1. Maxilla (anterior)
   - palatal processes
2. Palatine bone (posterior)
   - horizontal plates

Fissure in between: Palatomaxillary suture

3. Premaxilla
   - fuse with hard palate during development —> problem with fusing —> cleft palate —> but cleft palate rarely separates premaxilla into 2 halves at the middle (usually right / left side)

Question 6

Hard palate foramen

Answer 6

1. Incisive foramen
   - communication between nasal region and oral region
   - **Nasopalatine nerve (from nasal cavity to oral cavity)
   - **Greater palatine artery (from oral cavity into nasal cavity —> anastomoses with Sphenopalatine artery)
2. Greater palatine foramen
   - between palatine and maxilla on hard palate
   - Greater palatine artery
   - Anterior palatine nerve (Greater palatine nerve)
3. Lesser palatine foramen
   - perforate palatine bone
   - Middle + Posterior palatine nerve (soft palate) (***Lesser palatine nerve)

Question 7

Hard palate blood supply

Answer 7

Greater palatine artery:

Greater palatine artery (branch of Maxillary artery)
—> Greater palatine canal (with Anterior palatine nerve)
—> Greater palatine foramen
—> passes around hard palate
—> Incisive foramen
—> Nasal cavity (anastomoses with Sphenopalatine artery)

Question 8

Hard palate nerve supply

Answer 8

1. Anterior palatine nerve (from CNV2 —> Pterygopalatine ganglion)
   - from Greater palatine foramen up to Incisive foramen
2. Nasopalatine nerve (from CNV2 —> Pterygopalatine ganglion)
   - crosses nasal roof —> descend on nasal septum —> through Incisive foramen —> supply hard palate anterior to incisive foramen

Question 9

***Soft palate

Answer 9

Aponeurosis (of tensor veli palatini) acted upon by 5 pairs of muscles

1. Tensor veli palatini (CNV3)
2. Levator veli palatini
3. Palatopharyngeus muscle
4. Palatoglossus muscle
5. Muscular uvulae

Question 10

1. Tensor veli palatini (CNV3)

Answer 10

Origin:
- arise from basicranium and **lateral part of Cartilaginous part of Eustachian tube (outside of pharynx)
—> fibres converge towards base of pterygoid hamulus
—> flat tendon
—> **hooks around hamulus
—> go inside pharynx
—> becomes aponeurosis

Actions (拉開Eustachian tube):

1. ***Tenses up aponeurosis —> so other muscles can act on it
2. ***Pulls open cartilaginous part of Eustachian tube

Nerve supply:
- CNV3 (via nerve to medial pterygoid)

Question 11

2. Levator veli palatini (V shape)

Answer 11

Origin:
- inside Pharyngobasilar fascia
- from quadrate area on petrous part of temporal bone
- from **medial part of Cartilaginous part of Eustachian tube
—> round belly runs towards, medially, downwards (V-shaped sling)
—> insert onto **nasal (upper) surface of Palatine aponeurosis

Actions (扯起soft palate):
- Pull soft palate backwards + upwards
—> ***shutting nasopharynx from oropharynx (during swallowing)

Nerve supply:
- Pharyngeal plexus (CN10)

Question 12

3. Palatopharyngeus muscle (Inverted V)

Answer 12

Origin:
- 2 heads
- from horizontal plate of palatine bone
- from **back of Palatine aponeurosis
—> arches over lateral margin of Palatine aponeurosis
—> form **Posterior pillar of fauces
—> insert into ***Posterior border of Thyroid cartilage and Cornua

Actions (扯起pharynx):

1. ***Depresses soft palate
2. ***Elevates larynx and pharynx

Nerve supply:
- Pharyngeal plexus (CN10)

Question 13

4. Palatoglossus muscle

Answer 13

Origin:
- arises from **undersurface of Palatine aponeurosis
—> passes down to interdigitate with **Styloglossus (lateral tongue muscle)
—> form ***Anterior pillar of fauces

Actions:

1. Sphincter of oropharyngeal fauces
2. ***Raises tongue

Nerve supply:
- Pharyngeal plexus (CN10)

Question 14

5. Muscular uvulae

Answer 14

Origin:
- arises from posterior nasal spine and palatine aponeurosis
—> insert into mucous membrane of uvula

Actions:

1. Shape the uvula
2. ***Pull up uvula ipsilateral side

Nerve supply:
- Pharyngeal plexus (CN10)

Question 15

Tongue

Answer 15

• Mass of muscle
• Contain mucous + serous glands
• Covered with mucous membrane

Divided into:

1. Anterior 2/3: Oral cavity
2. Posterior 1/3: Oropharynx

Question 16

Anterior 2/3 tongue

Answer 16

• Thick fibrous mucous membrane (***Rough)
• Small projections: ***Papillae
  —> Filiform
  —> Fungiform
  —> Foliate
• ***NO glands on dorsum (upper surface)
• Prehencile (grabbing), for ***mastication

Question 17

Posterior 1/3 tongue

Answer 17

• in Oropharynx, NOT in mouth
• bound by **Sulcus terminalis (後d) / **Vallate papillae (前d)
• NO papilla posterior to Vallate papillae
• Mucous membrane: Nodular appearance because of **mucous and serous glands + **Lingual tonsil (part of Waldeyer’s ring)
• **Smooth, for **swallowing
• ***Foramen caecum (just behind apex of Vallate papillae) —> remnant of thyroglossal duct (descend of thyroid gland)

Question 18

***4 Lingual papillae

Answer 18

Anterior 2/3:
1. Filiform
- conical
- fur appearance
- ***no taste buds
(- somatosensory receptor: detect texture in food)

2. Fungiform
   - mushroom-shaped
   - visible as red dots
   - taste buds
3. Foliate
   - posterolateral border of tongue (側面)
   - serous glands
   - taste buds

Posterior 1/3:

4. Vallate (雖然係anterior 度, 但係當posterior tongue, ∵ innervated by ***CN9)
   - V-shape
   - 8-12 in number
   - immediately in front of Foramen caecum and Sulcus terminalis
   - taste buds

Question 19

Tongue muscles

Answer 19

Midline septum divide tongue into halves

• 4 Intrinsic
• 4 Extrinsic

Question 20

Intrinsic tongue muscles

Answer 20

• wholly within tongue
• no attachment to bones
• fibres in 3 planes perpendicular to each other

1. Superior longitudinal fibres (前後)
2. Inferior longitudinal fibres (前後)
   - alongside Genioglossus
   - medial to Hyoglossus
3. Transverse fibres (向左右延伸)
   - origin: Midline fibrous septum
   - insertion: 2 Sides of tongue
4. Vertical fibres (向下延伸)
   - origin: Mucous membrane of dorsum
   - insertion: 2 Sides of Lower part

Question 21

Extrinsic tongue muscles

Answer 21

• ALL supplied by CN12 (except Palatoglossus (Pharyngeal plexus: CN10))

1. Genioglossus (Genio: chin)
   - front: to mandible
2. Hyoglossus
   - down: to hyoid bone
3. Styloglossus
   - back: to styloid process (temporal bone)
4. Palatoglossus
   - up: to soft palate

Question 22

1. Genioglossus

Answer 22

• Fibres radiate widely
• Lateral to midline septum

Origin:
- ***Superior genial tubercle (Mandible)

Insertion:
- ***Mucous membrane (薄膜) of dorsum (upper surface) of tongue, lowest fibres go to hyoid (=/ geniohyoid muscle)

Nerve supply:
- CN12

Question 23

2. Hyoglossus

Answer 23

• Lateral to Genioglossus

Origin:
- body and length of greater horn of **Hyoid bone
—> extends as quadrilateral sheet on side of tongue
—> insert into **side of tongue (interdigitate with ***Styloglossus)

Nerve supply:
- CN12

Question 24

3. Palatoglossus

Answer 24

Origin:
- arises from **undersurface of palatine aponeurosis
—> passes down to interdigitate with **Styloglossus (lateral tongue muscle)
—> form ***Anterior pillar of fauces

Nerve supply:
- Pharyngeal plexus (CN10)

Question 25

4. Styloglossus muscles

Answer 25

- most lateral tongue muscle Origin: - from ***styloid process (temporal bone) to ***side of tongue Nerve supply: - CN12

Question 26

Movement of tongue

Answer 26

Function: - sucking, prehension of food, chewing, swallowing, speaking, toileting, gestures * **Shape —> altered by Intrinsic muscles: - transverse: narrow tongue and heaps up dorsum into convexity - transverse + vertical: dorsum convexity flattened —> smaller cross-sectional area —> elongate - transverse + vertical + genioglossus (lowest fibres) —> protrude tongue * **Position —> altered by Extrinsic muscles: - Genioglossus: ***Protrude root of tongue (lower fibres) - Styloglossus: ***Retract + Elevate tongue - Hyoglossus: Draw the side ***downwards - Palatoglossus: ***Elevate tongue Mylohyoid: elevate floor of mouth —> elevate tongue

Question 27

Tongue and Uvula lesion

Answer 27

Right CN12 lesion —> Right genioglossus affected —> Unopposed left side protrusion —> Tongue protrude to right side Right CN10 lesion —> Right Muscular uvulae affected —> Unopposed left side contraction —> Uvula deviate to left side

Question 28

Frenulum of tongue (脷根)

Answer 28

Mucous membrane fold extending from floor of mouth —> midline of inferior tongue Either side: Opening of Submandibular and Sublingual gland

Question 29

Tongue and swallowing

Answer 29

``` Food is masticated —> forming bolus —> conscious decision to swallow —> tongue push bolus backwards into oropharynx —> trigger swallowing reflex ``` 1. Soft palate raised (Levator veli palatini) —> temporarily close off nasopharynx from oropharynx 2. Pharyngeal muscles constrict in sequence —> pushing bolus into esophagus 3. Larynx elevates —> epiglottis close off larynx 4. Esophageal muscles drive bolus down by peristalsis

Question 30

Blood supply of tongue

Answer 30

Artery: 1. Lingual artery - branch from anterior branch of ***External carotid artery - passes deep to Hyoglossus towards tongue tip Venous drainage: 1. Deep lingual veins (Ranine veins): undersurface of tongue —> Common facial vein —> Internal jugular vein 2. Lingual veins —> Internal jugular vein

Question 31

Sensory innervation of tongue

Answer 31

Anterior 2/3 - general sensory: Lingual nerve (CNV3) - special sensory: Chorda tympani (CN7) (via Lingual nerve) - secretomotor (parasympathetic): Chorda tympani (CN7) (via Lingual nerve) Posterior 1/3 - general sensory, special sensory, secretomotor (parasympathetic): CN9

Question 32

Floor of mouth

Answer 32

1. Mylohyoid muscle (最底層) 2. Geniohyoid muscle 3. Hyoid bone

Question 33

1. Mylohyoid muscle

Answer 33

Origin: - ***Mylohyoid line (Mandible) Insertion: - Midline raphe - ***Hyoid bone (posterior fibres) Nerve supply: - ***CNV3

Question 34

2. Geniohyoid muscle

Answer 34

- Above Mylohyoid - Below Genioglossus - Important for positioning of hyoid bone —> positioning of larynx Origin: - ***Inferior genial tubercle (Mandible) (Genioglossus: Superior genial tubercle) Insertion: - upper border of ***Hyoid bone Nerve supply: - ***C1 (via CN12) (即係由C1黎 —> hitchhike CN12)

Question 35

***3. Hyoid bone

Answer 35

- U shape - Above larynx - Slung between Mandible and Styloid process by Geniohyoid (前) and Stylohyoid (後) - Important in positioning of larynx * **Elevate hyoid: 1. Geniohyoid (C1 via CN12) 2. Stylohyoid (CN7) 3. Mylohyoid (CNV3) * **Depress hyoid (Infrahyoid muscles): 1. Thyrohyoid (Ansa cervicalis) 2. Omohyoid (Ansa cervicalis) 3. Sternohyoid (Ansa cervicalis) (4. Sternothyroid —> drag entire larynx down) (Ansa cervicalis)

Question 36

***Hyoglossus as landmark

Answer 36

Lateral (Superficial) to Hyoglossus: 1. Lingual nerve (Submandibular ganglion for preganglionic cell from Chorda tympani CN7) 2. CN12 3. Submandibular duct 4. Stylohyoid muscle Medial to Hyoglossus: 1. CN9 2. Lingual artery 3. Genioglossus 4. Stylohyoid ligament

Question 37

Submandibular gland

Answer 37

Superficial part - below / lateral to Mylohyoid - lies in Submandibular fossa - covered by deep cervical fascia - curves around posterior border of Mylohyoid (包住Mylohyoid的後面) Deep part - above / medial Mylohyoid - lies in floor of mouth - between mandible and side of tongue * **Submandibular duct - opening at anterior end of deep part —> ***Sublingual papilla - runs between Sublingual gland and Genioglossus Anatomical relationships: - Facial artery: grooves the gland (before turning around inferior border of mandible) - Common facial vein: grooves the gland - CN7 Mandibular branch: crosses the gland

Question 38

Sublingual gland

Answer 38

- in front of Anterior border of Hyoglossus - between Mylohyoid and Genioglossus - below termination of Submandibular duct - about 15 ducts —> 1/2 open into Submandibular duct —> Sublingual papilla —> 1/2 open directly on Sublingual fold + Sublingual papilla

Question 39

Teeth

Answer 39

Deciduous teeth (milk teeth) —> total 20 - central and lateral incisors - canine - 2 molars Permanent teeth —> total 32 - central and lateral incisors - canine - 2 premolars - 3 molars Upper: Maxillary teeth Lower: Mandibular teeth

Question 40

Teeth nerve supply

Answer 40

Upper: CNV2 (Superior alveolar nerve: anterior, middle, posterior) Lower: CNV3 (Inferior alveolar nerve)

Question 41

Dental occlusion

Answer 41

Class I: Normal Class II: Distal occlusion: Maxilla protrude anteriorly Class III: Mesial occlusion (倒及): Mandible protrude anteriorly