Development of the face Flashcards
What are neural crest cells populations of
Transient populations of ectodermal cells
Where do neural crest cells develop
Within the crest if the neural folds in the cranio- caudal axis of the embryo
Where do neural crest cells migrate
Many parts of the body where they behave like stem cells
What week do the branchial arch appear
3rd week
Where do the branchial arch develop
Either side of the developing foregut
How many pairs of branchial arches are there
5 (1 to 6)
What develops from approx week 4
Small bulges called rhombomeres develop laterally from the developing hindbrain
They migrate forward from the back of the head to where the face and front of neck would be to provide the majority of ectomesenchyme to the development of the pharyngeal structures
What separates the head from the cardiac bulge
Pharyngeal arches (they proliferate and migrate forward until they meet their counterpart)
What is each arch associated with
- Mesenchyme/ ectomesenchyme
- Specific artery
- Arch associated cranial nerve
- A covering of ectoderm
- A lining of endoderm cartilage
Where are the pharyngeal grooves (clefts) located
Between each of the pharyngeal arches
What happens to the pharyngeal grooves
Some will develop into pharyngeal pouches. Each branchial arch will grow downwards and forwards
How do components of the 3rd and 4th arch grow
Components overgrow the second arch and lie adjacent to the first
Name of each of the arches
1st - Mandibular 2nd - Hyoid 3rd- third 4th- fourth 6th- sixth
What cartilage is associated with the first arch
Meckel’s cartilage
What is the importance of Meckel’s cartilage
Posteriorly, each Meckel’s cartilage terminates in an enlargement called the malleus
The malleus lies adjacent to a small cartilage, the incus
Further posteriorly is a third body of cartilage, the stapes
The malleus, incus, and stapes later transform into the hearing bones of the middle ear
, for the first 20 weeks of prenatal life
The contact point between the malleus and incus is the articulation of the lower jaw
The second temporomandibular joint between the condyle and temporal fossa becomes functional later
Early mandible of fetus
What is the cartilage derivative of the arches
1st - Malleus, incus, sphenomandibular ligament
2nd- Stapes, stylohyoid ligament, lesser horn and upper part of body of hyoid bone
3rd - Greater horn and lower part of body of hyoid
4th - Thyroid cartilage
6th - Arytenoid cartilage
What muscles are associated with each arch
1st - Muscles of mastication, ant belly of digastric, mylohyoid
2nd - Stapedius, stylohyoid, facial muscles, buccinator
3rd - Stylopharnygeus
4th- Pharyngeal and extrinsic laryngeal muscles
6th - Intrinsic laryngeal muscles
What nerves are associated with each arch
1st - Mandibular 2nd- Facial 3rd - Glossopharyngeal 4th - Vagus - superior laryngeal 6th - Vagus - recurrent laryngeal
What are the 5 processes that the face develops from
Frontonasal, 2 x mandibular, 2 x maxillary
What stops the 2 maxillary processes from meeting
Frontonasal structure
Explain the development of the nasal cavity
- The ectoderm of the frontal prominence thickens, forming the nasal placodes
- Then mesoderm underneath the placodes proliferates and forms the nasal pits
- Then there is extension backwards which forms the nasal cavity
What are the structures that the anterior 2/3 of the tongue develop from
The structures develop within the primitive stomatodeum. The tuberculum impar (single) and lateral lingual swellings (paired)
Where does the thyroid tissue start to develop
Foramen Caecum
What branch does the anterior 2/3 of the tongue originate from
First arch
