Embryology of the Head and Neck Flashcards
Describe Apert Syndrome.
Premature FUSION of Coronal Sutures
- Acrocephalic (“Tower Skull”) appearance
- Associated with Smoking or Alcohol use during Pregnancy
Describe the EARLY development of the face.
*** Most of the face development occurs during Weeks 4-5
1st Arch –> Maxillary and Mandibular Processes
Maxillary Swellings and Frontonasal Prominence fuse!
What induces the Evagination of Ectoderm to form the Stomadaeum?
What is the stomadaeum?
Primitive Pharynx
Earliest Analog to the Oral Cavity
Describe the main players when we are talking about development of the Nose and the Mouth.
Nasal Placode –> Invaginates to the form the Nasal Pit
- Frontonasal Prominence
- Maxillary Swellings
- Mandibular Swellings
- Stomodaeum
The second arch is going to give rise to which main structure?
FACIAL NERVE (CN VII)
Failure of the Maxillary Prominence to fuse will result in what?
Oblique Facial Cleft
The Frontonasal Prominence is going to give rise to which structures?
Nose (Nasal Pits, Takes ECTODERM inward) and Fuses @ the Midline of the Upper Lip (Filtrum)
Going to Give rise to the Roof of the PALATE
**** Eyes are super WIDE in the early embryo and you have to have elongation of the face in order to bring them closer together.
If the Medial Nasal Prominences do not fuse together, what is going to happen?
What about the Lateral Nasal Prominences?
Medial –> Cleft right down the CENTER of your NOSE
Lateral –> Has to Fuse with the MAXILLARY Swelling; OBLIQUE FACIAL Cleft
What happens if the Mandibular Swelling DOES NOT develop?
It won’t push the ears OUT LATERALLY!
When the Medial Nasal Prominences fuse what do they form?
INTERMAXILLARY Process
- This will form the:
1. Nasal SEPTUM
2. Primary PALATE
Describe Treacher-Collins Syndrome.
FIRST ARCH malformation of the MIDFACE
- Impaired growth of the bones in the MIDFACE (Small chin, enlarged nose, cleft palate which may also include cleft lip)
**** Approximately 40-50% of all people with Treacher-Collins experience some level of AURAL complications (results in conductive hearing loss)
Describe the development of the Palate.
Medial Nasal Prominences fuse as intermaxillary process and the Primary Palate is formed
Secondary Palate is formed by the Palatine Shelves of the Maxillary Swellings
PALATINE SHELVES have to FUSE or you will NOT have a Palate!
Differentiate between:
- Anterior Cleft Palate
- Bilateral Anterior Cleft Palate
- Posterior Cleft Palate
Anterior Cleft Palate –> Part of Intermaxillary Process DID NOT fuse with the Palatine Shelves
Bilateral Anterior Cleft Palate –> Frontonasal Prominence DOES NOT fuse with the Maxillary Swellings and the Palatine Shelves
Posterior Cleft Palate –> Palatine Shelves DO NOT fuse with each other
Differentiate between:
- Holoprosencephalic Defects of the Midface
- Bilateral Cleft Lip
Holoprosencephalic Defects of the Midface –> Bilateral CLEFT defect due to FAILURE of INTERMAXILLARY PROCESS to form (Fetal Alcohol Syndrome)
Bilarteral Cleft Lip –> Failure of MEDIAL NASAL PROCESSES to fuse with the MAXILLARY SWELLINGS
What are the different nerves associated with each Branchial Arch?
Arch 1 –> V3 (Only part of Trigeminal that Innervates MUSCLES!)
Arch 2 –> VII
Arch 3 –> IX
Arch 4 –> X (Cricothyroid)
Arch 6 –> X (Recurrent Laryngeal Nerve)
Describe Thyroglossal Cysts.
Remnants of the migration of the THYROGLOSSAL Duct
Remnants may also include Ectopic THYROID TISSUE!
*** Can be taken out but you have to determine if it is not a FUNCTIONAL part of the thyroid (undescended Thyroid)
