S6) Development of the Head, Neck and Face Flashcards
Describe the structure of the pharyngeal arches
Pharyngeal arches are comprised of a system of mesenchymal proliferations in the neck region of the embryo
![](https://s3.amazonaws.com/brainscape-prod/system/cm/223/764/977/a_image_thumb.jpg?1509386829)
How many pharyngeal arches are there?
5 in total, numbered 1 to 6 (5th does not form in humans)
![](https://s3.amazonaws.com/brainscape-prod/system/cm/223/765/035/a_image_thumb.jpg?1509386840)
Identify the components which constitute the building blocks for the head and neck region
- Pharyngeal arches
- Frontonasal prominence (FNP)
![](https://s3.amazonaws.com/brainscape-prod/system/cm/223/765/754/a_image_thumb.png?1509386984)
Describe the association of the cranial nerves with the pharyngeal apparatus
- Cranial nerves – CN V, CN VII, CN IX & CN X
- Functions:
I. Mixed sensory & motor functions
II. Supply the derivatives of the pharyngeal arches
Describe how the muscles of the face are derived from the pharyngeal arches
- Ph Arch 1: muscles of mastication
- Ph Arch 2: muscles of facial expression
State the 3 muscles derived from the 4th pharyngeal arch
Ph Arch 4:
- Cricothyroid
- Levator palatini
- Constrictors of the pharynx
![](https://s3.amazonaws.com/brainscape-prod/system/cm/223/766/665/a_image_thumb.png?1509387944)
State the muscles derived from the 3rd and 6th pharyngeal arches
- Ph Arch 3: stylopharyngeus
- Ph Arch 6: intrinsic muscles of the larynx
![](https://s3.amazonaws.com/brainscape-prod/system/cm/223/766/731/a_image_thumb.png?1509387986)
Each of the pharyngeal arches develops a neural crest.
Identify the cartilages of the 1st & 2nd pharyngeal arches
- Ph Arch 1 – Meckel’s cartilage: malleus, incus + a template for formation of the mandible
- Ph Arch 2 – Reichert’s cartilage: stapes + upper part hyoid bone
![](https://s3.amazonaws.com/brainscape-prod/system/cm/223/766/771/a_image_thumb.png?1509388054)
Each of the pharyngeal arches develops a neural crest.
Identify the cartilages of the 3rd, 4th & 6th pharyngeal arches
- Ph Arch 3 – remainder of hyoid bone
- Ph Arch 4 & 6 – cartilages of the larynx
![](https://s3.amazonaws.com/brainscape-prod/system/cm/223/766/879/a_image_thumb.png?1509388064)
The aortic sac lies in floor of the pharynx.
Hence, in light of this describe the derivatives of the pharyngeal arch arteries
![](https://s3.amazonaws.com/brainscape-prod/system/cm/223/766/905/q_image_thumb.png?1509388337)
- Ph arch 1&2 arteries disappear
- Ph arch 3 artery = internal carotid artery
- Ph arch 4 artery = arch of aorta (L) & subclavian artery (R)
- Ph arch 6 artery = pulmonary arteries
![](https://s3.amazonaws.com/brainscape-prod/system/cm/223/766/905/a_image_thumb.png?1509388239)
What is a pharyngeal pouch?
Pharyngeal pouches are endoderm lined pockets in the pharynx
![](https://s3.amazonaws.com/brainscape-prod/system/cm/223/767/050/a_image_thumb.jpg?1509388373)
The first pharyngeal pouch is the largest.
What is its derivative?
Pharyngotympanic tube and middle ear cavity
What is the derivative of the second pharyngeal pouch?
Palatine tonsils
What are the derivatives of the third pharyngeal pouch?
- Inferior parathyroid
- Thymus gland
What are the derivatives of the fourth pharyngeal pouch?
- Superior parathyroid gland
- C cells of thyroid gland
What is a pharyngeal cleft?
Pharyngeal clefts are grooves which form in the lateral ectodermal surface of the neck region to separate the arches
![](https://s3.amazonaws.com/brainscape-prod/system/cm/223/767/136/a_image_thumb.jpg?1509388553)
Describe the fate of the first pharyngeal cleft
1st pharyngeal cleft is remains and becomes the external acoustic meatus
What happens to the other pharyngeal clefts (besides 1)?
Ph arch 2 grows down to cover others, obliterating all other clefts
Which conditions can occur if there are remnants of other pharyngeal clefts?
Branchial cysts or fistulae can occur