Pharyngeal arches/ Branchial arches
Pharyngeal arches/ Branchial arches
Pharyngeal arches are structures that are critical to the understanding of the development and the anatomy of head and neck.
Sometimes they are referred to in the literature as visceral arches, or branchial arches, but the term pharyngeal arches is currently preferred.
What are pharyngeal arches?
Pharyngeal arches are a series of five paired swellings that may be seen to surround the embryonic foregut from day 20 to day 35 of development.
These arches are numbered 1,2,3,4, and 6.
Pharyngeal arches are unique to vertebrates.
Components of a pharyngeal arch
If you look at a coronal section of an embryo, you can see that a pharyngeal arch has ectoderm on the outside, endoderm on the inside, and mesenchyme between the two epithelia.
Mesenchyme derived from neural crest cells lies at the periphery, and the central core is filled with mesodermal mesenchyme.
Each arch has its own artery, nerve, cartilage rod “skeleton”, and a group of muscle cells.
1st arch
A massive list of Ms
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Nerve
|
Artery
|
Cartilage
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Musclemat×2
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Maxillary and mandibular nerves
|
Maxillary artery
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–Meckel’s cartilage
– Mandible + sphenomandibular ligament
– malleus + incus |
– muscles of mastication
– mylohyoid – anterior belly of digastric – anterior 2/3 of tongue – tensor veli palatini – tensor tympani |
2nd arch
Second
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Nerve
|
Artery
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Cartilage
|
Muscle
|
|
Facial nerve
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Stapedial artery and hyoid artery
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– styloid
– lesser horn of hyoid – stylohyoid ligament
– stapes
|
– muscles of facial expression (smiling)
– stapedius – stylohyoid – posssterior belly of digastric |
3rd Arch
Think Glossopharyngeal nerve
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Nerve
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Artery
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Cartilage
|
Muscle
|
|
Glossopharyngeal nerve
|
Greater horn of hyoid
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Stylopharyngeus
|
4th Arch
Swallowing + the exceptions to the 6th arch below
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Nerve
|
Artery
|
Cartilage
|
Muscle
|
|
Superior laryngeal (branch of vagus)
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– thyroid cartilage
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– pharyngeal constrictors
– levator veli palatini – cricothyroid |
6th Arch
Speaking (laryngeal)
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Nerve
|
Artery
|
Cartilage
|
Muscle
|
|
Recurrent laryngeal (branch of vagus)
|
All laryngeal cartilages except thyroid cartilage
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All instrinsic laryngeal muscles except cricothyroid
|
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