10. Morphology and histology of the oral cavity, soft palate and the faucial isthmus soon: morphology and histology of the tongue and the salivary glands 4th semester: morphology and histology of the teeth Mark Kozsurek, M.D., Ph.D. ED I., 22/02/2017

Oral cavity extends from the oral fissure to the oropharyngeal isthmus and can be divided into the oral vestibule (outside the dental arch) and the oral cavity proper (inside the teeth). Is bounded superiorly by the palate, inferiorly by the oral diaphragm and laterally by the cheeks.

The roof of the oral cavity: the palate

incisive papilla: pear-shaped swelling over the incisive foramen palatine rugae: several (3-7) transverse folds of the mucosa of the hard palate (choping and grinding of foods, phonation, sucking) palatine raphe: longitudinal mucosal fold in the midline palatinae foveolae: openings of the excretory ducts of the small salivary glands of palate

hard palate soft palate palatine glands hard palate soft palate fibromuscular structure covered by the pseudostratified ciliated columnar epithelium of the nasal cavity and the stratified squamous non-keratinized epithelium of the oral cavity

Bony base of hard palate palatine proc. of maxillae horizontal plate of palatine bone median and transvers palatine sutures incisive canal greater and lesser palatine foramina Most of the mammals have obvious incisive suture and incisive bone but in human tipically a complete fusion is seen. If observable, incisive bone consits of a body, a palatine process, an alveolar process and a nasal process.

Muscles of the soft palate palatine aponeurosis Uvula Muscles of the soft palate

palatine aponeurosis 1. Tensor veli palatini: medial plate of pterygoid proc., scaphoid fossa and cartilage of auditory tube → in the palatine aponeurosis after a 90 degree turn at the hook of pterygoid proc.

M. tensor veli palatini M. levator veli palatini M. palatopharyngeus 2. Levator veli palatini: inferior surface of the apex of petrous part of temporal bone and the cartilage of the auditory tube → palatine aponeurosis

Note the appearance of the levateor and tensor veli palatini muscles from an inferior aspect!

M. tensor veli palatini M. levator veli palatini M. palatopharyngeus 3. Palatoglossus: connects the root of tongue with the palatine aponeurosis. 4. Palatopharyngeus: arises from the soft palate, radiates into the wall of pharynx.

M. tensor veli palatini M. levator veli palatini M. palatopharyngeus 5. Uvularis muscles: originate from the posterior nasal spine and form the chief bulk of uvula

Innervation of palatine muscles pharyngeal plexus: CN IX-X-(XI) Uvula CN X. (VII. ?) pharyngeal plexus: CN IX-X-(XI) CN X.

Note that arteries and nerves of the palate share the same name! Innervation and blood supply of the palate Descending palatine artery: (labelled on the picture as greater palatine artery) from sphenoplatine branch of maxillary artery coming from the pterygopalatine fossa Incisive artery terminal branch of nasopalatine artery arising from the spenopalatine branch of maxillary artery Ascending palatine artery a direct branch from facial artery Greater and lesser palatine nerves from ganglionic branches of maxillary nerve descending from the Incisive nerve nerve from ganglionic branches of the maxillary nerve Note that arteries and nerves of the palate share the same name! All these vessels are the branches of the maxillary artery and are not asked in details in this semester. Similarly, nerves will be fully covered only durintg the 3rd semester!

The floor of the oral cavity: the oral diaphragm

The main contributor of the oral diaphragm is the mylohyoid muscle (backwards it is replaced by the hyoglossus). Above the mylohyoid the two paralelly positioned geniohyoid muscles are seen, while anterior bellies of the digastric muscle are attached to the inferior surface of it. (Tongue might be considered as a mucosa-covered muscular structure emerging from the oral floor.)

Lateral wall of the oral cavity: the cheeks

Structure of the lips and cheeks is roughly the same, and we have already seen the lip in the histo lab! Skin stratified squamous keratinized epithelium, connective tissue papillae, sebaceous and sweat glands Buccinator muscle Mucosa stratified squamous non-keratinized epithelium, connective tissue papillae, buccal glands

(oropharyngeal isthmus) Isthmus of the fauces (oropharyngeal isthmus)

As a GP sees…

As you see in the dissection room… original position of oropharyngeal membrane endoderm ectoderm

The following structures should be identified: root of the tongue, palatoglossal and palatopharyngeal folds, tonsillary fossa, palatine tonsil, oropharynx

Lymphatic ring of Waldeyer

Tonsils Tonsil or MALT (mucosa associated lymphatic tissue) or lymphoepithelial organ. Right under the epithelium lymphoid cells are embedded into a reticular network formed by reticulum cells and reticular fibres. Lymphocytes destroy the basement membrane and infiltrate the epithelium resulting in a unique mixture of the epithelial and lympatic tissues. The surface is increased by folds and invaginations. The secondary follicles represent the B-dependent zones, among the follicles the T-dependent regions are present.

T-dependent zone B-dependent zone

Blood supply of the (palatine) tonsils (= descending palatine artery)

Clinical considerations

Relation of the palatine tonsil to the retropharyngeal and parapharyngeal spaces.

Tonsillectomy: removal of the palatine tonsil uvula palatine tonsil

Peritonsillar and retropharyngeal abscess

Thank you for your attention!