Embryology Pharyngeal Cleft Derivatives Flashcards
CN of First Arch
Trigeminal
CN of Second Arch
Facial
CN of Third Arch
Glossopharyngeal
CN of Fourth Arch
Superior Laryngeal of Vagus
CN of Sixth Arch
Recurrent laryngeal branch of Vagus
Stenosis/Atresia
Ear Canal Nasal Passage Larynx Esophagus Trachea
Clefts
Ear pit Nasal Masses Face Lip Palate Larynx Tracheal-Esophageal
Persistent Structures
Thyroglossal duct
Branchial cleft
Skeletal Derivatives of the First Arch
Maxillary prominence: Maxilla, Zygomatic, Squamous part of temporal bone.
Mandibular prominence: Merkel’s cartilage (Mandible), Reichert’s cartilage (Inner ear); malleus, incus
Skeletal Derivatives of Second Arch
Stapes, styloid process, upper body of hyoid bone.
Skeletal Derivatives of Third Arch
Greater cornu and lower body of hyoid bone
Skeletal Derivatives of Fourth and Sixth Arch
Thyroid and Cricoid Cartilage.
First Pharyngeal Pouch Derivatives
Auditory Tube
Tympanic or middle ear cavity
Mastoid Air Cells
Second Pharyngeal Pouch Derivatives
Palantine tonsils
Third Pharyngeal Pouch Derivatives
Thymus
Inferior parathyroid glands
Fourth Pharyngeal Pouch Derivatives
Superior Parathyroid glands Ultimobranchial bodies (aka parafollicular cells of thyroid)
1st membrane persists as
Tympanic Membrane
1st cleft forms
External Auditory Meatus
2nd, 3rd, and 4th Clefts form
Cervical sinus which normally disappears.
Lateral cervical (branchial) cyst or fistula when it persists
Thyroid embryology
Endodermal evagination from floor of pharynx between 1st and 2nd pouches forms the thyroid diverticulum which makes the follicular cells.
4th pharyngeal pouch makes the ultimaobranchial body which makes the parafollicular cells.
Follicula cells and parafollicular cells combine to make thyroid gland.
Common branchial cysts
1st arch 8%
2nd arch is 90%
