Overview of nasal and oral cavities Flashcards
What are the boundaries of the nasal cavity?
The nasal cavity is a bony box divided between orbits & anterior floor of cranial fossa and palate.
- its open front and back
- serves as airway to foregut
- conditions and monitors air during passage through it.
Ontogeny and phylogeny implications:
Ectodermal placodes in frontal prominence invaginate and special sensory cells (CN I) in roof of nasal pit sense dissolved chemicals; remainder of pit is ordinary ectoderm
- in the higher forms nasal pits breakthrough oral cavity
- palate divides nasal and oral cavities only in mammals and reptiles
- -allows breathing while chewing and only mammels chew.
What are the boundaries of the oral cavity:
Lips to palatoglossal folds (at the junction of anterior 2/3 and posterior 1/3 of the tongue.
What are jaws and why are they so special?
- Jaws (Modified pharyngeal arches) added out front of stomodaeum (cranial end of gut)
- Interior of jaws forms most of the oral cavity
- -Formed by forwarding growth of maxillary & mandibular swelling from the anterior end of the gut.
- Jaws are under voluntary control but gut is not
- -at the palatoglossal fold(approximate location of stomodeum, lose voluntary control
- Jaws armed with teeth for defense and reducing food have large ectoderm component (Modified scales
What supplies the jaws and why?
by branches of the external carotid artery supplies the jaws because they are added secondarily to the skull.
Whats “taste” and where is it focused in the foregut?
Taste is a means of distinguishing edible from not. It is focused in the back of the oral cavity. just in front of entry of gut.
What develops the tongue?
The tongue is formed from cervical myotomes and migrates into oral cavity dragging its motor supply (CN XII) with it.
What innervates the tongue?
The tongue moves through territories of several cranial nerves (V, VII, IX, X) and acquires general sensory from V and IX. It acquires special sensory (taste from VII, IX, and X.
