Head and Neck I Flashcards
What are the origin of developmental structures of the head, connective tissue and skeletal structures
Neural crest origin
What is the head region of embryo associated with?
Developing nervous, digestive and respiratory systems
What is a key distinguishing feature of head development?
Formation of pharyngeal arches
How many pairs of pharyngeal arches exist?
6 pairs
What does first pharyngeal arch become?
Divided into a maxillary and mandibular process
Where is the first pharyngeal arch located and what does this allow?
Immediately caudal to oropharyngeal membrane that now seals off foregut
What does development of the face involve?
Formation, fusion and patterning of facial primordia that surround stomodeal depression
What does primordia form from?
Proliferation of neural crest-derived mesenchyme
What do nasal and lens placodes form from?
Fronto-Nasal prominence
Slide 6
What is a cleft lip the result of?
When the fusion of the nasomedial process and maxillary prominences does not occur properly, philtrum is not formed properly
In early stages of development what separates maxillary from nasal prominences?
A deep Naso-lacrimal groove
Where does the naso-lacrimal groove extend towards?
Developing eye
What occurs to the floor of the naso-lacrimal groove?
Floor of this ectodermal groove will lose contact with surface to form canalized cord of cells
What is the canalized cord of cells produced by the floor of the naso-lacrimal groove known as?
Nasolacrimal duct
What separates nasal sacs from oral cavity?
Oro-nasal membrane which forms primary palate
What leads to the development of maxillary process?
Common nasal cavity forms at the caudal end of the nasal sacs and caudal part of palate atrophies
What is the direct communication between caudal portion of nasal cavity and oral cavity known as?
Choana
Where does palatine process begin to grow from?
Lateral walls of nasal cavity
What generates the secondary palate?
Developing tongue fills the oral cavity and pushes into the nasal cavity, this causes expansion of the palatine processes and fusion at the midline
What occurs where palate is fusing with maxillary process, and what are these called?
Small spaces in the palate remain - incisive ducts
What do incisive ducts allow for?
Allow small amounts of fluid from oral cavity to paired vomeronasal organ and to olfactory epithelium of nasal cavity
What are projections of laminae arising from lateral walls of nasal cavity called?
Conchae
What do conchae become and how?
Turbinate bones
Become ossified
What are the three passages in the nasal cavity called?
Meatus
What does the amount of fusion between nasal septum and secondary palate help to determine?
The communication between pharynx and nasal cavities
What occurs in horses with regard to secondary palate?
Nasal septum fuses iwth secondary palate along entire length so each nasal cavity communicates separately with pharynx
How does secondary palate differ between horses and all other domestic animals?
Fusion is not so extensive and nasal cavities have a common opening into nasopharynx in domestics
How does soft palate come to be?
Portion of the palate that projects into pharynx remains membranous dividing pharynx into oral and nasal parts
How is cleft palate classified?
Primary - Due to incomplete fusion of nasomedial processes with maxillary prominences
Secondary - Due to incomplete fusion of lateral palatine processes. Leaving opening between oral and nasal cavities
Basic structure of teeth?
Enamel
Dentin
Cementum
