CLEFT ANOMALIES,pharyngeal pounch

What is a branchial fistula?

Abnormal canal connecting pharynx or skin due to failure of fusion of 2nd arch with epicardial ridge. Can be external, internal, or both

What is a lateral cervical cyst?

Remnant of the cervical sinus. Located along the anterior border of the sternocleidomastoid muscle

What are pharyngeal pouches and how many are there?

Endodermal outpocketings between arches. 5 pairs, with the 5th often considered part of the 4th

What does the 1st pharyngeal pouch form?

Tubotympanic recess →Distal part: Tympanic cavity (middle ear). Proximal part: Auditory tube

What does the 2nd pouch form?

Primordium of the palatine tonsil. Tonsil is later infiltrated with lymphatic tissue. Remnant forms the tonsillar fossa

What does the 3rd pouch form?

Dorsal wing → Inferior parathyroid glands. Ventral wing → Thymus. Thymus descends into thorax, dragging the parathyroid

What does the 4th pouch form?

Superior parathyroid glands, which attach to the thyroid

What does the 5th pouch (part of 4th) form?

Ultimobranchial body, which becomes the parafollicular cells (C cells) of the thyroid. These secrete calcitonin