Oral Cavity & Pharynx

Which bones form the hard palate?

Palatine process of the maxilla (anterior) and horizontal plate of the palatine bone (posterior)

What does the incisive canal connect?

The oral cavity to the nasal cavity

What passes through the greater palatine foramen?

Palatine nerves to the hard palate (greater palatine n.)

What passes through the lesser palatine foramina?

Palatine nerves to the soft palate (lesser palatine n.)

What passes through the mandibular foramen?

Inferior alveolar nerve, artery, and vein

What exits through the mental foramen?

The mental nerve

What attaches to the genial spines?

Tongue and floor-of-mouth muscles (e.g., genioglossus, geniohyoid)

What type of growths are mandibular tori and torus palatinus?

Benign bony (osseous) overgrowths

Location of mandibular tori

Usually bilateral, near the roots of the canine teeth (lingual mandible)

Location of torus palatinus

Midline of the hard palate

Which torus is more common?

Torus palatinus (~20%) vs. mandibular tori (8-15%)

What marks the boundary between the oral cavity and oropharynx?

The palatoglossal arch

Which arches frame the palatine tonsil?

Palatoglossal arch (anterior) and palatopharyngeal arch (posterior)

Pterygomandibular fold (raphe)

A visible mucosal landmark lateral to the palate

Why are palate and lip prints useful forensically?

Palate rugae (palatoscopy/rugoscopy) and lip prints (cheiloscopy) are fixed for life, like fingerprints

3 classifications of palatal rugae patterns

Vertical, reticular, branched

Sensory innervation of the hard palate

Greater palatine n. (mostly) + nasopalatine n. (around the incisive canal); both V2

Sensory innervation of the soft palate

Lesser palatine n. (V2)

How does the nasopalatine nerve reach the palate?

Through the incisive canal

Nasopalatine nerve block anesthetizes:

The anterior hard palate (around the incisive papilla)

Greater palatine nerve block anesthetizes:

The posterior hard palate (often reaching the lesser palatine n./soft palate too)

Nerves to the maxillary teeth

Posterior, middle, and anterior superior alveolar nn. (V2), descending from the infraorbital n.

Why do maxillary teeth require regional injections?

They're supplied by many separate V2 nerves (PSA, MSA, ASA, infraorbital blocks)

What does "alveolar" mean in a nerve name?

It refers to the bony tooth sockets, so all alveolar nerves supply teeth

Nerve to the mandibular teeth

Inferior alveolar n. (V3)

Territory of the buccal (long buccal) nerve

Inner and outer surfaces of the cheek (V3)

Territory of the mental nerve

Chin and the inner and outer lower lip (branch of the inferior alveolar n.)

Territory of the auriculotemporal nerve

Skin of the temple/ear region (V3)

Why does an inferior alveolar nerve block numb the tongue and lower lip?

The nearby lingual and mylohyoid nn. are usually affected, and the mental n. (from the IAN) numbs the lower lip

Does an IANB numb both sides?

No, only the injected side (there are 24 cranial nerves, 12 per side)

What can teeth sense?

Only pain (bimodal: pain or no pain); no temperature, touch, or pressure

5 cranial nerves innervating the oral cavity and pharynx

V (trigeminal), VII (facial), IX (glossopharyngeal), X (vagus), XII (hypoglossal)

CN IX's only somatic motor target

Stylopharyngeus

What marks the boundary between the anterior 2/3 and posterior 1/3 of the tongue?

The vallate papillae and sulcus (terminalis)

Tongue innervation summary: general sensation and taste

Anterior 2/3: general = lingual n. (V3), taste = chorda tympani (VII); posterior 1/3: both = CN IX

What minor role does CN X play in tongue sensation?

The far posterior tongue/epiglottic region

How many cranial nerves carry tongue sensation, counting both sides?

6 (3 per side: V3, VII, IX)

Where are the sensory cell bodies for general sensation from the anterior 2/3 tongue?

Trigeminal ganglion

Where are the sensory cell bodies for taste from the anterior 2/3 tongue?

Geniculate ganglion (CN VII)

What does the chorda tympani carry besides taste?

Preganglionic parasympathetics to the submandibular ganglion

4 parasympathetic ganglia of the head

Ciliary (CN III), pterygopalatine (CN VII), submandibular (CN VII), otic (CN IX)

Are any autonomic ganglia in the head sympathetic?

No; all are parasympathetic (sympathetics already synapsed at the superior cervical ganglion)

Sensory ganglia of the head (no synapses)

Trigeminal (V), geniculate (VII), superior and inferior ganglia of IX and X

What are sensory ganglia analogous to?

Dorsal root ganglia

Origin of the genioglossus

Superior genial tubercles (spines)

Origin and insertion of the styloglossus

Styloid process -> posterior tongue (near hyoglossus)

Origin and insertion of the hyoglossus

Greater horn of the hyoid -> lateral tongue

What innervates the intrinsic tongue muscles?

CN XII

Is tongue MOTOR innervation divided into anterior 2/3 vs. posterior 1/3?

No; all tongue muscles are CN XII (except palatoglossus, CN X)

Course of CN XII

Exits via the hypoglossal canal, turns anteriorly, passes deep to mylohyoid and superficial to hyoglossus, enters the tongue from below

Which way does the tongue deviate with hypoglossal nerve damage?

Toward the damaged side (ipsilateral)

Why does the tongue deviate ipsilaterally in CN XII damage?

The intact genioglossus on the healthy side pushes the tongue forward and across toward the weak side

Tongue vs. uvula deviation

Tongue (CN XII): toward the damaged side; uvula (CN X): away from the damaged side

Location of the parotid gland

External to the ramus of the mandible

Where does the parotid duct open?

Near the 2nd maxillary molar

Location of the submandibular gland

Just anterior and mostly medial to the angle of the mandible

Where does the submandibular duct open?

Sublingual caruncle

Location and drainage of the sublingual gland

Floor of the mouth, posterior to the anterior mandible; drains via small ducts in the floor of the mouth

How many minor salivary glands are there?

Up to 1,000 (labial, palatine, pharyngeal)

Rule of thumb for parasympathetic innervation of head glands

All are CN VII EXCEPT the parotid (CN IX); sweat glands excluded

Parasympathetic pathway to the submandibular and sublingual glands

Superior salivatory nucleus -> CN VII -> chorda tympani (petrotympanic fissure) -> lingual n. (V3) -> submandibular ganglion -> glands

Parasympathetic pathway to the parotid gland

Inferior salivatory nucleus -> CN IX -> tympanic n. -> lesser petrosal n. (foramen ovale) -> otic ganglion -> auriculotemporal n. (V3) -> parotid

Which nucleus starts the CN VII salivary pathway? The CN IX pathway?

CN VII: superior salivatory nucleus; CN IX: inferior salivatory nucleus

Pathway to the palate, nasal, and lacrimal glands

CN VII -> greater petrosal n. -> Vidian n. -> pterygopalatine ganglion

3 sets of tonsils and their locations

Pharyngeal (nasopharynx); palatine (between the palatoglossal and palatopharyngeal arches); lingual (posterior tongue)

Most common serious complication of tonsillectomy

Delayed hemorrhage (2-4% of patients)

Arteries supplying the tonsils

Descending palatine, ascending palatine, ascending pharyngeal, dorsal lingual, tonsillar aa.

How many soft palate muscles are innervated by CN X?

4 of 5; tensor veli palatini is the exception (V3)

Why is tensor veli palatini innervated by V3?

It's considered an accessory muscle of mastication

Course of the tensor veli palatini

Two bellies arise at the scaphoid fossae; the tendon hooks around the pterygoid hamulus (medial pterygoid plate)

What does tensor veli palatini do besides tensing the soft palate?

Opens the Eustachian tube to equalize middle ear pressure

Origin of the levator veli palatini

near skull base

Action of the palatopharyngeus

Shortens the oropharynx during swallowing

Action of the musculus uvulae

Shortens and widens the uvula; helps close the nasopharynx during swallowing

Which way does the uvula deviate with unilateral CN X damage?

Away from the damaged side (contralateral); e.g., right CN X damage -> uvula deviates left

Why does the uvula deviate contralaterally in CN X damage?

The intact side's levator veli palatini pulls the uvula toward itself

Boundaries of the oropharynx

Soft palate (uvula) to the epiglottis; palatoglossus anteriorly to the superior/middle constrictors posteriorly

Contents of the oropharynx

Palatine and lingual tonsils, palatopharyngeus, superior and middle constrictors

Where do the 3 constrictors unite posteriorly?

Pharyngeal raphe

Anterior attachment of the superior constrictor

Pterygomandibular raphe (also pterygoid hamulus)

Anterior attachment of the middle constrictor

Greater horn of the hyoid

Anterior attachment of the inferior constrictor

Oblique line of the thyroid cartilage

In what order do the constrictors contract?

Sequentially: superior -> middle -> inferior

Origin of the stylopharyngeus

Styloid process

Origin of the salpingopharyngeus

Eustachian (auditory) tube

Origin of the palatopharyngeus

Palate

Rule for pharyngeal muscle innervation

All CN X EXCEPT stylopharyngeus (CN IX)

Incisive canal

Identify the structure at #1

Alveolar bone

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Horizontal plate (of palatine bone)

Identify the structure at #3

Medial and lateral pterygoid plates

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Palatine process (of maxilla)

Identify the structure at #5

Greater, lesser palatine foramina

Identify the structure at #6

Hamulus

Identify the structure at #7

Mandibular foramen

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Genial spines

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Mylohyoid line

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Mylohyoid groove

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Head

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Neck

Identify the structure at #6