1. ORAL CAVITY

2. Objectives
Name the parts of the oral cavity and describe their boundaries, communications and anatomical features
Name the parts of the palate and describe their composition and anatomical features
Describe the location, action and nerve supply of the muscles of the soft palate
Describe the blood and sensory nerve supply of the palate
Name the parts of the tongue and describe their anatomical features
Describe the location, action and nerve supply of the extrinsic muscles of the tongue
Name the intrinsic muscles of the tongue and indicate their nerve supply

3. Objectives
Describe the origin, course, anatomical relations, branches and distribution of the glossopharyngeal nerve
Describe the origin, course and distribution of the lingual artery
Describe the location and anatomical relations of the submandibular and sublingual glands and their ducts
List the types and numbers of deciduous and permanent teeth
Describe the parts of a tooth

4. Oral Cavity
entry portal of digestive system  extends from lips, anteriorly, to oropharyngeal isthmus, posteriorly (communication between oral cavity and oropharynx)
parts: vestibule and oral cavity proper
vestibule:
space between lips and cheeks, externally, and teeth and gingiva, internally
communicates with exterior through oral fissure (space between lips)
labial frenula  2 midline mucosal folds connecting mucosa on inner aspect of lips to gingiva between central incisor teeth
parotid papilla  small elevation on buccal mucosa, opposite 2nd maxillary molar  marks opening of parotid duct into oral vestibule

8. Oral Cavity Proper boundaries: anterior and lateral: teeth and gingiva
posterior: oropharyngeal isthmus (communication between oral cavity and oropharynx)  space between right and left palatoglossal arches
superior: palate
inferior: mylohyoid muscles (form a muscular diaphragm that supports tongue and structures of floor of mouth  this diaphragm is reinforced medially by geniohyoid muscles)

11. Palate parts: hard palate (anterior ⅔) and soft palate (posterior ⅓)
formed by palatine processes of maxillae and horizontal plates of palatine bones
covered with mucosa which is tightly bound to underlying bone
soft palate:
movable posterior ⅓ of palate, which is suspended from posterior border of hard palate
has no bony skeleton
when relaxed, extends posteriorly and inferiorly into pharynx (separates nasopharynx from oropharynx)

12. Palate soft palate (cont.):
has a posterior free border with a midline conical projection (uvula)
on each side, soft palate becomes continuous with 2 arches (folds):
palatoglossal arch  located anteriorly  extends from soft palate to side of tongue
palatopharyngeal arch  located posteriorly  extends from soft palate to pharyngeal wall
tonsillar sinus (fossa)  triangular interval between palatoglossal and palatopharyngeal arches of same side  occupied by palatine tonsil

16. Muscles of the Soft Palate
levator veli palatini:
located immediately under mucosa of nasopharynx, just inferior to pharyngeal opening of auditory tube
action: elevates soft palate to separate nasopharynx from oropharynx (important during swallowing to prevent passage of food into nasopharynx and nasal cavity)
tensor veli palatini:
located anterior and slightly lateral to levator veli palatini muscle and medial to medial pterygoid muscle  its tendon curves around pterygoid hamulus
action: tenses soft palate and assists with its elevation, opens pharyngeal opening of auditory tube

17. Muscles of the Soft Palate
palatoglossus:
located within palatoglossal arch  extends from soft palate to side of tongue
action: elevates root of tongue, approximates palatoglossal arch to its contralateral fellow
palatopharyngeus:
located within palatopharyngeal arch  extends from soft palate to pharyngeal wall and thyroid cartilage of larynx
action: elevates pharynx and larynx during swallowing, approximates palatopharyngeal arch to its contralateral fellow
uvular muscle: located in midline and extends into uvula  shortens uvula and pulls it superiorly

18. Nerves and Vessels of the Palate
motor innervation: tensor veli palatini is supplied by medial pterygoid nerve (from V3), all other muscles are supplied by pharyngeal branch of vagus
sensory innervation: greater and lesser palatine nerves, nasopalatine nerve, tonsillar branches of glossopharyngeal nerve
arteries: greater and lesser palatine arteries (from maxillary artery), ascending palatine artery (from facial artery), palatine branch of ascending pharyngeal artery
veins drain into pterygoid venous plexus and pharyngeal venous plexus  pharyngeal plexus communicates with pterygoid venous plexus and drains also into internal jugular vein

22. Tongue highly muscular organ covered by a mucous membrane functions:
speech
manipulation and positioning of food
tasting
swallowing
cleansing of oral cavity

23. Tongue parts: root: posterior ⅓  lies in oropharynx
body: anterior ⅔  lies in oral cavity proper  ends anteriorly in apex (tip) of tongue
dorsum: superior roughened surface
inferior (sublingual) surface: faces floor of oral cavity proper  covered with thin, transparent mucosa
right/left margins: separate dorsum and inferior surface on each side

24. Tongue surface features:
terminal sulcus: V-shaped groove located on dorsum of tongue  its apex points posteriorly in midline  divides dorsum of tongue into oral or presulcal part (anterior ⅔) and pharyngeal or postsulcal part (posterior ⅓)
foramen cecum: small pit at apex of terminal sulcus  remnant of superior end of thyroglossal duct (connects thyroid gland to tongue during development)
median sulcus: shallow midline groove on dorsal surface of oral part of tongue  divides tongue into right and left halves
lingual frenulum: mucosal fold that connects inferior surface of tongue to floor of oral cavity proper in midline

25. Tongue surface features (cont.):
deep lingual vein: can be observed through mucosa of inferior surface, on either side of frenulum
sublingual caruncle (papilla): small elevation just lateral to base of lingual frenulum  marks opening of submandibular duct
sublingual fold: fold of mucosa of floor of oral cavity proper caused by underlying sublingual gland  directed posteriorly and laterally from sublingual caruncle

28. Mucosa of the Dorsum of the Tongue
oral (presulcal) part:
velvety appearance due to presence of papillae
filiform papillae: most numerous  project as tapering, threadlike points  impart rough texture to dorsum of tongue  aid in handling food  contain general sensory nerve endings, but no taste buds
fungiform papillae: scattered among filiform papillae  mushroom-like and reddish
vallate papillae: large papillae, 8 to 12 in number  form V- shaped row anterior and parallel to terminal sulcus  each papilla is surrounded by circular trough

29. Mucosa of the Dorsum of the Tongue
oral (presulcal) part (cont.):
foliate papillae: found on lateral margins of tongue as short vertical folds (better developed in other mammals)
fungiform, vallate and foliate papillae contain taste buds
pharyngeal (postsulcal) part:
no papillae are present
characterized by rounded elevations caused by lymphoid nodules, which collectively form lingual tonsil

32. Muscles of the Tongue
extrinsic muscles: originate outside tongue and insert into tongue
intrinsic muscles: originate and insert within tongue
extrinsic muscles:
genioglossus: originates from mental spine of mandible (above origin of geniohyoid)  fibers fan out posteriorly and superiorly into tongue  right and left muscles, acting together, pull tongue forward (protrude tongue) in midline  if genioglossus muscle of one side is not fully functional (usually as a result of CN XII lesion), tip of tongue deviates toward affected side on attempted protrusion

33. Muscles of the Tongue extrinsic muscles (cont.):
hyoglossus: thin quadrilateral muscle  originates from greater and lesser horns and body of hyoid bone  fibers pass superiorly and anteriorly to insert into lateral aspect of tongue  depresses tongue (fibers that originate from lesser horn are sometimes considered a separate muscle [chondroglossus])
styloglossus: originates from styloid process  fibers pass anteriorly and inferiorly to insert into lateral aspect of tongue  draws tongue up and backward
palatoglossus is described by some authors as a tongue muscle
intrinsic muscles: superior and inferior longitudinal, transverse and vertical muscles

35. Unilateral Hypoglossal Nerve Lesion

37. Nerve Supply of the Tongue
motor nerve supply: extrinsic and intrinsic muscles are supplied by hypoglossal nerve (exception: palatoglossus  supplied by vagus nerve via its pharyngeal branch)
general sensory nerve supply: lingual nerve (branch of V3)  anterior ⅔; glossopharyngeal nerve  posterior ⅓; vagus nerve (via internal laryngeal nerve)  small area adjacent to epiglottis
special sensory nerve supply (taste): facial nerve (via chorda tympani)  anterior ⅔; glossopharyngeal nerve  posterior ⅓ (including vallate papillae); vagus nerve (via internal laryngeal nerve)  small area adjacent to epiglottis

39. Glossopharyngeal Nerve
contains sensory and motor fibers
arises from medulla of brainstem  exits skull via jugular foramen  has 2 sensory ganglia (superior and inferior glossopharyngeal ganglia)  descends posterior to stylopharyngeus muscle  passes between superior and middle constrictor muscles to enter pharynx  passes anteriorly through tonsillar bed (lateral to palatine tonsil) and ends in posterior ⅓ of tongue
branches:
tympanic nerve: forms tympanic plexus, which gives general sensory innervation to mucosa of tympanic cavity  gives rise to lesser petrosal nerve (carries preganglionic parasympathetic fibers to otic ganglion)

40. Glossopharyngeal Nerve
branches (cont.):
carotid branch: descends on internal carotid artery to supply baroreceptors and chemoreceptors of carotid sinus and carotid body, respectively
muscular branch: supplies stylopharyngeus muscle
pharyngeal branches: supply sensory innervation to a large part of pharyngeal mucosa
tonsillar branches: supply sensory innervation to mucosa of palatine tonsil and posterior end of soft palate
lingual branches: supply general sensory and special sensory (taste) innervation to mucosa of posterior ⅓ of tongue, including vallate papillae

44. Lingual Artery
anterior branch of external carotid artery  passes medial to hyoglossus muscle, which separates lingual artery from hypoglossal nerve  at anterior border of hyoglossus muscle it turns upward and forward to reach tip of tongue (this distal part is known as deep lingual artery)
supplies tongue, palatine tonsil, sublingual gland, mylohyoid and geniohyoid muscles and mucosa of floor of mouth

46. Submandibular Gland
one of the major salivary glands (together with parotid and sublingual glands)
wraps around posterior border of mylohyoid muscle and has superficial and deep parts
superficial part (larger)  located in submandibular (digastric) triangle of neck
deep part (smaller)  located above mylohyoid muscle, between mandible (lateral to gland) and hyoglossus muscle (medial to gland)  gives rise to submandibular duct
submandibular duct: passes forward, medial to sublingual gland  opens into floor of oral cavity proper at tip of sublingual caruncle (papilla)  lingual nerve passes inferior to submandibular duct, crossing it from lateral to medial, before entering tongue

47. Sublingual Gland smallest of the major salivary glands
rests on floor of mouth between mandible (lateral to gland) and genioglossus muscle (medial to gland)  covered superiorly by mucosa of floor of mouth (forms sublingual fold)
about 12 small ducts originate from superior border of gland  open separately along sublingual fold of floor of mouth (a few of the more anterior ducts may drain into submandibular duct)

51. Teeth
children have 20 deciduous (primary, milk) teeth  in each half of maxillary and mandibular dental arches there are 5 teeth:
2 incisors
1 canine
2 molars
adults have 32 permanent (secondary) teeth  in each half of maxillary and mandibular dental arches there are 8 teeth:
2 premolars
3 molars

52. Teeth parts: crown: projects from gingiva
root: fixed in alveolus by periodontal ligament (number of roots varies depending on type of tooth)
neck: slightly constricted area between crown and root
most of tooth is composed of dentin, which is covered by enamel over crown and cement over root
pulp cavity contains connective tissue, blood and lymph vessels and nerves
root canal transmits nerves and vessels to and from pulp cavity through apical foramen

56. Paranasal Sinuses