Pharyngeal Arch (complete) Flashcards
What are the parts that make up the pharyngeal apparatus
- Pharyngeal arches
- Pharyngeal grooves/crests
- Pharyngeal pouches
- Pharyngeal membrane
In what week does the pharyngeal apparatus begin to develop
in the 4th week
What happens simultaneously with the development of the pharyngeal apparatus
Neural crest cells migrate into the head and neck region
What are the pharyngeal arches and where are they located
They are the protrusions or bumps and they are on the external surface of the fetus
Where are the pharyngeal grooves/clefts and where are they located
they are the invaginations or indentations between the pharyngeal arches and they are on the external surface of the fetus
Where are the pharyngeal pouches and where are they located?
They are the indentations or invaginations on the internal surface of the fetus
What is found in each of the pharyngeal arches
- Nerve
- Muscle
- cartilage (bone precursor)
- Artery
Where do neural crest cells come from
- They begin as the borders of the neural plate
- when the neural plate folds up they form the layer of cells that converge upon each other
- when the neural tube is completely formed the neural crest cells follow the tube in and are sealed under the newly formed ectoderm.
- They then travel from the posterior/dorsal neural tube region to the anterior/ventral region
How many pharyngeal arches are there
6 total, but the 5th disintegrates. so only 5 relevant ones
How many pharyngeal grooves/clefts are there
4
how many pharyngeal pouches are ther
4
What do the neural crest cells carry with them
their own genetic code
What is the stomodaeum
a cavity formed by the ectoderm folding in towards the buccopharyngeal membrane
What does the stomodaeum develop into
the mouth (oral cavity)
what is the stomodaeum lined with
ectoderm
What is the germ layer that is responsible for most things that develop in the oral cavity
the ectoderm
What separates the stomodaeum and the primitive pharynx
the buccopharyngeal membrane
What is another name for the arches that can be used instead of pharyngeal
brachial arches
What aggregates to form the arches, grooves/clefts, and pouches
mesenchyme
What makes up the external layer of the aches and grooves
ectoderm
what makes up the internal layer where the pouches are found
endoderm
What is the arch artery that develops from the 3rd arch
common carotid artery
root of internal carotid
What is the arch artery that develops from the 2nd arch
stapedial artery (embryonic) corticotympanic (adult)
What is the arch artery that develops from the 6th arch
Ductus Arteriosus
root of definitive pulmonary arteries
What is the arch artery that develops from the 1st arch
Terminal branch of the maxillary artery
What is the arch artery that develops from the 4th arch
Arch of aorta
right subclavian artery
What are the skeletal elements that develop from the 1st arch
- Mandible
- Maxilla
- Incus
- Zygomatic bone
- malleus
- Squamuous portion of temporal bone
What are the skeletal elements that develop from the 3rs arch
hyoid bone (part)
What are the skeletal elements that develop from the 4th arch
- laryngeal cartilage (thyroid, cuneiform, cricoid, corniculus)
- possibly the epiglottis
What are the skeletal elements that develop from the 6th arch
- laryngeal cartilage (thyroid, cuneiform, cricoid, corniculus)
What are the skeletal elements that develop from the 2nd arch
- stapes
- styloid process
- hyoid (part)
What are the muscles that develop from the 2nd arch
Muscles of facial expression
- obicularis oris
- orbicularis occuli
- buccinator
- frontalis
- platysma
What are the muscles that develop from the 3rd arch
- stylopharyngeus
What are the muscles that develop from the 1st arch
Muscles of mastication
1. masseter
2, temporalis
3. pterygoids
What are the muscles that develop from the 4th arch
Constrictors of pharynx
What are the muscles that develop from the 6th arch
intrinsic muscles of larynx
What is the cranial nerve that develops from the 1st arch
Trigeminal nerve V
What is the cranial nerve that develops from the 2nd arch
Facial Nerve VII
What is the cranial nerve that develops from the 6th arch
Vagus nerve X
What is the cranial nerve that develops from the 3rd arch
Glossopharyngeal nerve IX
What is the cranial nerve that develops from the 4th arch
Vagus nerve X
What does the 1st cleft/groove form
External auditory meatus
external ear tube
What does the 2nd, 3rd, and 4th clefts/grooves form
The Cervical Sinus
What usually happens to the cervical sinus
It normally resorbs and goes away
What happens if the cervical sinus doesn’t completely resorb
a cervical cyst or fistula develops
What is the difference between a cyst and a fistula
A cyst doesn’t have any access to the external world
A fistula does have access to the external world, and can leak fluids
What causes the formation of the cervical sinus
rapid proliferation of the 2nd pharyngeal arch that grows over the 2nd 3rd and 4th clefts
Where would you see a cervical cyst or fistula
the Lateral border of the neck
What does the 1st pharyngeal pouch develop into
the pharyngotympanic tube
inner ear tube
What does the 3rd pharyngeal pouch develop into
inferior parathyroid gland and thymus
What does the 2nd pharyngeal pouch develop into
palatine tonsil
what does the 4th pharyngeal pouch develop into
superior parathyroid gland and ultimo brachial body
What does the ultimo brachial body interact with
the thymus
How does the inferior parathyroid gland end up below the superior parathyroid gland when it starts out above it
the inferior parathyroid gland hitches a ride with the thymus, and that pulls it down below the superior parathyroid
Where does the primitive thyroid form
at the midline of the pharynx just below the tuberculum impar
Where does the thyroid originiate
the Foramen Cecum
what does the migration of the thyroid form
the thyroglossal duct
what can cause a thyroglossal duct cyst/foramen
when the thyroglossal duct formed by the migration of the thyroid doesn’t degenerate
How can you distinguish between the thyroglossal cyst and the cervical cyst
cervical cysts will be lateral on the neck
thyroglossal cysts will be right in the middle of the neck
When does the development of the tongue begin
the 4th week
From what does the anterior 2/3rds of the tongue develop
- Lateral lingual swellings
2. tuberculum impar (median tongue bud)
From what does the posterior 1/3rd or root of the tongue develop
From the copula
From what do the lateral lingual swellings, the tuberculum impar, and therefor the anterior 2/3rd of the tongue develop
the 1st pharyngeal arch
from what does the copula and therefor the posterior 2/3rds of the tongue develop
From arch #3
what is the foramen cecum
a tiny hole through which the thyroid passes, this is the origin of the thyroid