Oral Cavity (FINAL)

Branchial arches

Paired pouches on anterolateral surface of embryo heads

Associated with arterial arches of developing heart/vasculature

Each arch connected to brainstem by a nerve

Branchial arches naming

Named by which aortic arch enters them

1st, 2nd, 3rd, 4th, 6th (5th arch enters 5th arch) or 5/6

Arch innervation by CNs

1st: Trigeminal, V, Pons

2nd: Facial, VII, Pons

3rd: Glossopharyngeal, IX, Medulla

4th: Vagus, X, Medulla

5th: Spinal accessory, XI, Medulla

Law of Integrity of Nerve Supply

A nerve will follow wherever a tissue grows

First arch divisions

Maxillary (cranial) and mandibular (caudal)

Plurisegmental muscles

Muscles that are innervated by multiple nerves

Branches that innervate the diaphragm

CN II, IV, V

Keep you alive

Pretrematic branch of trigeminal

Goes into head → Gives rise to ophthalmic, maxillary, mandibular nerves

Pretrematic branch of facial

Chorda tympani → Taste buds

Pretrematic branch of 5/6

Cervical spinal cord sends a branch in

Why traps are innervated by spinal cord

Face development

2, 3, 4, 6, and mandibular division of 1 extend medially and fuse at midline

Nasomedial process of head mesenchyme move inferiorly between maxillary arches

Cholaboma

Inferior opening on iris because embryonic tissue comes down and doesn’t fuse

What innervates the tip of the nose

CN V

Cleft/hare lip

Maxillary arch doesn’t fuse with frontal nasal process

Can affect suckling if continues into palate

Oral cavity

Divided into oral vestibule and oral cavity proper

Oral vestibule

Lips to teeth

Oral cavity proper

Teeth to fauces

Oral cavity roof

Palate

Hard: Anterior 2/3, bone (maxillary and palatine)

Soft: Posterior 1/3, muscle

Oral cavity walls

Lips and cheeks

Oral cavity floor

Muscle

Geniohyoid, mylohyoid, anterior belly digastric

Oral cavity posterior wall

Fauces

Palatoglossal plane

Fauces

Muscle arches covered by skin

Anterior arch: Palatoglossal muscle

Posterior arch: Palatopharyngeal muscle

Palatoglossal muscle

Pulls tongue up in swallowing

Palatine fossa

Between anterior and posterior fauces arches

Contains palatine tonsils

Soft palate

4th arch muscles: Palatoglossus, palatopharyngeal, levator palatine, musculus uvulae (CN X) and 1st arch mandibular division (CN V3)

1st arch mandibular division: Tensor palatine (CN V3)

Uvula

Covers nasopharynx when swallowing, pulled by musculus uvulae (2)

Deviates toward healthy side in CN X damage

Oral cavity floor muscles

Geniohyoid (suprahyoid muscle), mylohyoid, stylohyoid, hypoglossus muscles

Submandibular triangle

Contains submandibular salivary gland and lymph nodes

Submental triangle

Contains lymph nodes

Tongue body

Innervated by lingual branch of V3 (sensory) and chorda tympani of VII for taste

Skin comes from mandibular division of 1st arch

Tongue root

Innervated by IX for touch and taste, sustained stimulation → Gag

Skin comes from 3rd arch

Lingual tonsil below skin

Sulcus terminalis

Where body and root of tongue meet

Foramen cecum

Where thyroid embryonically emptied

Dysgusia

Bad taste at back of throat

Eyedrops stimulate these tastebuds

Waldeyer’s Ring

2 Pharyngeal, 2 palatine, 2 tubal, lingual tonsils form a ring around neck

Intrinsic tongue muscles

Change shape of the tongue

Innervated by XII

Extrinsic tongue muscles

Move tongue in space

XII: Styloglossus (up and back), genioglossus (protrude), hypoglossus (pull down)

X: Palatoglossus, pulls

How do you check CN XII

Ask patient to stick tongue out

Deviates toward the paralyzed size

Dorsal surface of tongue

Lingual vein runs in plica fimbriata (sublingual drug route)

Lingual frenulum can continue forward and hold tongue down (ankyloglossia)

Sublingual caruncle openings for submandibular glands

Muscles of mastication

Innervated by CN V3

Masseter (pull up and protrude, very strong), temporalis (retract), lateral/medial pterygoid (open, protrude, rock)

Buccinator

Innervated by VII

Food gets stuck in oral vestibule in Bells palsy

Oropharynx

Starts at fauces and runs from tip of uvula to superior epiglottis