H&N 2.2 branchial arches Flashcards
When does the neural tube form?
Week 3
How does the neural tube form?
notochord signals for overlying ectoderm to thicken, causing a slipper shaped elevation of neurectoderm. This rolls up to from the neural tube
What does the anterior neural tube become?
The future brain, therefore it rapidly proliferates
What are the 3 vesicle stages of the brain development?
prosencephalnon- forebrain
mesencephalon- midbrain
rhombencephalon- hindbrain
Where does the pharynx extend from and to?
What are it’s divisions?
From the base of the skull to the inferior border of the cricoid cartilage.
Nasopharynx
Oropharynx
Laryngopharynx
What are the pharyngeal arches?
Mesenchymal proliferations in the neck region of the embryo
how many pharyngeal arches are there?
5 in total,
1,2,3,4, and 6
What 2 distinct portions does the first pharyngeal arch split into?
Maxillary prominence and the mandibular prominence
What cells are crucial for the development of the head and neck?
Neural crest cells, which migrate from elsewhere.
Which nerves are derived from the pharyngeal arches?
Ph arch 1- trigeminal nerve
Ph arch 2- facial nerve
Ph arch 3- glossopharyngeal nerve
Ph arch 4 and 6- vagus nerve
What muscles are derived from Ph arch 1?
Muscles of mastication
What muscles are derives from Ph arch 2?
Muscles of facial expression
What muscles are derived from Ph arch 3?
What’s its function?
The stylopharyngeus only- aids in elevating pharynx and larynx during swallowing.
What muscles are derived from Ph arch 4?
Cosntrictors of the pharynx,
What muscles are derived from Ph arch 6?
Intrinsic muscles of the larynx.
What nerve gives special sensation to the anterior 2/3 of the tongue?
Chorda tympani, a branch of the facial nerve
What nerve gives special sensation to the posterior 1/3 of the tongue?
The glossopharyngeal nerve.
What are the 2 divisions of the vagus nerve, and from which Ph arches are they derived?
Ph arch 4- superior laryngeal nerve
Ph arch 6- recurrent laryngeal nerve.
What’s the function of the superior laryngeal nerve?
innervates constrictors of the phayrnx
What’s the function of hte recurrent laryngeal nerve?
Innervates the intrinsic muscles of the larynx
What cartilage is derived from Ph arch 1?
Meckel’s cartilage, derived from the mandibular prominence.
What are the derivatives fo the cartilage bar fromed from Ph arch 1?
Template for the mandible (membranous ossification)
malleus, incus.
What cartilage is derived from Ph arch 2?
Reichert’s cartilage.
What are the derivatives of the cartilage bar formed from Ph arch 2?
The superior hyoid bone,
The styloid process
The stapedius.
What are the derivatives of the 1st and 2nd aortic arches?
There are none, they dissappear.
What are the derivates of the 3rd aortic arch?
Internal carotid artery
What are the derivates of the 4th aortic arch?
on the left, forms the arch of the aorta.
On the right, from the brachiocephallic artery.
What are the derivatives of the 6th aortic arch?
Forms the pulmonary arch.
Are the pharyngeal pouches found on the inside or the outside?
Inside, they’re covered by endoderm.
What does the 1st pharyngeal pouch form?
The tympanic cavity and the eustachian tube.
What does the 2nd pharyngeal pouch form?
The pallatine tonsils
What does the 3rd pharyngeal pouch form?
Joins the 4th,
Dorsal portions form the parathyroid glands
Ventral portions form the thymus.
What does the 4th pharyngeal pouch form?
Joins with the 3rd,
Dorsal portions form the parathyroid glands
Ventral portions form the thymus
Where are the pharyngeal clefts found?
On the outside, between the arches, coverred in ectoderm.
What is special about the 1st pharyngeal cleft?
It’s the only one that remains
What is derived from teh 1st pharyngeal cleft?
The external auditory meatus.
What problems can occur with regards to the pharyngeal clefts?
They can not fully close up, leading to branchial cysts and fistulae
Where would you find pharyngeal cysts and fistulae?
Along the anterior border of the sternocleidomastoid, therefore within the anterior triangle.
What is a pharyngeal pouch and what becomes of them?
outpocketings of the primitive gut tube in the pharynx.
Become glandular tissue.
