Last Day Revision
On this page 3 sections
Arch, nerve and muscle
| Arch | Nerve | Most important muscle clue |
|---|---|---|
| 1st | V3 | Muscles of mastication |
| 2nd | VII | Muscles of facial expression |
| 3rd | IX | Stylopharyngeus |
| 4th | X — superior laryngeal | Cricothyroid and pharyngeal constrictors |
| 6th | X — recurrent laryngeal | Intrinsic laryngeal muscles except cricothyroid |
Pouches, clefts and membranes
| Structure | High-yield derivative |
|---|---|
| First pouch | Middle ear cavity and auditory tube |
| Second pouch | Palatine tonsil epithelium/crypts |
| Third pouch | Thymus and inferior parathyroids |
| Fourth pouch | Superior parathyroids |
| First cleft | External acoustic meatus |
| Second–fourth clefts | Normally obliterated |
| First membrane | Tympanic membrane |
| Persistent cervical sinus | Branchial cyst/sinus |
Occipital somites and tongue
| MCQ clue | Answer |
|---|---|
| Origin of tongue muscles | Occipital somites |
| Motor nerve to most tongue muscles | CN XII |
| Exception to CN XII motor supply | Palatoglossus — CN X |
| Anterior two-thirds general sensation | Lingual nerve, V3 |
| Anterior two-thirds taste | Chorda tympani, VII |
| Posterior one-third sensation and taste | CN IX |
| Epiglottic region sensation | CN X |
| First arch cartilage | Meckel cartilage |
| Second arch cartilage | Reichert cartilage |
| First arch artery remnant | Maxillary artery contribution |
| Third arch artery | Common carotids and proximal internal carotids |
| Left fourth arch artery | Part of arch of aorta |
| Right fourth arch artery | Proximal right subclavian artery |
| Sixth arch artery | Pulmonary arteries; left distal portion forms ductus arteriosus |