Tuesday, June 29, 2010

Branchial Arches

A lot of people, myself included, have trouble memorizing the development of the branchial apparatus. Hopefully with these mnemonics, this process will be much easier for you. It definitely helped me. Along with congenital heart disease, this seems to be the highest yield topic in Embryology for the USMLE Step 1.

1st Arch: a Massive list of M’s

Nerve: Maxillary and Mandibular nerves

Artery: Maxillary artery

Cartilage: Meckel’s Cartilage
- Mandible + sphenoMandibular ligament
- Malleus + Incus

Muscles: MAT x 2
- Muscles of Mastication
- Mylohyoid
- Anterior belly of digastric
- Anterior 2/3 of tongue
Tensor veli palatini
- Tensor tympani

PS: for every one you get right reward yourself with an M&M  :D

2nd arch: Second

Nerve: Seventh nerve (facial nerve)

Artery: Stapedial artery and hyoid artery

- Stapes
- Styloid
- Stylohyoid ligament
- leSSer horn of hyoid

- Muscles of facial expression (Smiling)
- Stapedius
- Stylohyoid
- poSSSterior belly of digastric

3rd arch: think Glossopharyngeal nerve

- Glossopharyngeal nerve

- Greater horn of hyoid

- Stylopharyngeus

4th Arch: Swallowing + The exceptions to the 6th arch below

Nerve: Superior Laryngeal (branch of vagus)

- Thyroid cartilage

- Pharyngeal constrictors
- Levator veli palatini
- Cricothyroid

6th Arch: Speaking (Laryngeal)

Nerve: Recurrent laryngeal (branch of vagus)

Cartilage: All laryngeal cartilages except thyroid cartilage

Muscles:  All instrinsic laryngeal muscles except cricothyroid