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

Nerve	Artery	Cartilage	Musclemat×2
Maxillary and mandibular nerves	Maxillary artery	–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

Nerve	Artery	Cartilage	Muscle
Facial nerve	Stapedial artery and hyoid artery	– styloid – lesser horn of hyoid – stylohyoid ligament – stapes	– muscles of facial expression (smiling) – stapedius – stylohyoid – posssterior belly of digastric

3rd Arch

Think Glossopharyngeal nerve

Nerve	Artery	Cartilage	Muscle
Glossopharyngeal nerve		Greater horn of hyoid	Stylopharyngeus

 

4th Arch

Swallowing + the exceptions to the 6th arch below

Nerve	Artery	Cartilage	Muscle
Superior laryngeal (branch of vagus)		– thyroid cartilage	– pharyngeal constrictors – levator veli palatini – cricothyroid

6th Arch

Speaking (laryngeal)

Nerve	Artery	Cartilage	Muscle
Recurrent laryngeal (branch of vagus)		All laryngeal cartilages except thyroid cartilage	All instrinsic laryngeal muscles except cricothyroid

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