H&N 9.3 Development of the nose and face Flashcards
When does the neural tube form in embryonic development?
week 3
What structures lead to the formation of the head and neck?
The pharyngeal arches/ branchial arches
What drives development of the face?
- Expansion of the neural tube
- development of the special sense organs
- the appearance of tissues involved in the cranial gut tube and the developing heart outflow.
What are neural crest cells?
a specialised population of cells that originate within the neurectoderm.
(“a 4th germ lineage”)
Where about do the neural crest cells come from?
The lateral border of the neurectoderm
They then enter the mesoderm and migrate (to contribute with various head and neck structures)
What are the major features of the face?
- palpebral fissures
- nares
- oral fissure
- philtrum
What is the philtrum?
the groove in the upper lip that extends up to the nose.
What are the palpebral fissues?
the openings in the eye lids
What are the major bones and muscles of the face, and their origins?
- Facial skeleton- from the neural crest of the 1st pharyngeal arch
- muscles of mastication- from the mesoderm of the 1st pharyngeal arch
- muscles of facial expression- from the mesoderm of the second pharyngeal arch
What are the primary facial primordia?
- Frontonasal prominence
- stomatodeum
- 1st pharyngeal arch (maxillary and mandibular prominence)
What is the stomatodeum?
A depression in the developing face that will go on to give the mouth.
It contains the buccopharyngeal membrane at it’s center.
Where is the fronto-nasal prominence found?
Around the ventro-lateral aspects of the brain.
What external features does the FNP give rise to?
- forehead
- nose
- bridge of nose
- philtrum
What external features does the maxillary prominence give rise to?
- cheeks
- lateral upper lip
- lateral upper jaw
What external features does the mandibular prominence give rise to?
-the lower lip and jaw.
What are the nasal placodes?
How do they develop?
Depressions which apprear fairly laterally on the FNP.
They sink to form nasal pits, which will eventually become nostrils.
Either side of the nasal pits you get medial and lateral prominences.
How do the medial nasal prominences develop?
They get pushed more medially by the development of the maxillary prominence.
They eventually fuse at the midline, and fuse with the maxillary prominence.
What is formed when the medial nasal prominences and the maxillary prominence fuse?
The intermaxillary segment.
What does the intermaxillary segment go on to form in the mature face?
- the labial component of the philtrum (middle upper lip)
- the primary palate
- the medial 4 upper incisors.
What is the secondary plate formed of in the face?
The palatal shelves of the maxillary prominences and the pallatine bones.