Derivatives of Germ layesr

Question 1

Derivatives of pharyngeal membranes.

Answer 1

only the first pair of pharyngeal membranes give rise to definite structure –> tympanic membrane

Question 2

Derivatives of clefts.

Answer 2

only first pair of clefts give rise to definite structure –> external auditory meatus

Question 3

Derivatives of 1st pouch

Answer 3

Tubotympanic recess

Eustachian tube

Question 4

Derivatives of 2nd pouch

Answer 4

Tonsillar crypts

Question 5

Derivatives of 3rd pouch

Answer 5

Inferior parathyroid glands

Thymus

Question 6

Derivatives of 4th pouch

Answer 6

Superior parthyroid glands

Question 7

Derivatives of Meckel’s cartilage

Answer 7

Ventral part –> Mandible

Dorsal part –> Malleus and incus

Question 8

The stapes arises from which structure

Answer 8

Reichert’s cartilage

Question 9

Stylohyoid ligament arises from

Answer 9

Reichert’s cartilage

Question 10

Nerve of the 3rd pharyngeal arch

Answer 10

Glossopharyngeal nerve

Question 11

Thyroid and cricoid cartilage derived from

Answer 11

fusion of cartilages of 4th and 6th arch

Question 12

Muscles of 6th pharyngeal arch

Answer 12

Intrinsic muscles of larynx

Question 13

Constrictors of pharynx derived from

Answer 13

4th pharyngeal arch

Question 14

First Arch syndromes refers to

Answer 14

facial anomalies caused by failure of neural crest cells to migrate into first pharyngeal arch

Question 15

List the first arch syndromes

Answer 15

Treacher Collins/Mandibulofacial dysostosis
Pierre Robin Syndrome
DiGeorge syndrome

Question 16

DiGeorge syndrome

Answer 16

One of the syndromes associated with lack of neural crest cells to migrate to first pharyngeal arch

• fish mouth deformity
• lack of thymus and parathyroid glands = tetany due to PTH no longer present to maintain calcium in plasma and ECF

Question 17

Treacher collins syndrome

Answer 17

malar hypoplasia
mandibular hypoplasia
downslanding palpebral fissure

Question 18

Branchial cleft cyst

Answer 18

failure of 2nd pharyngeal cleft to completely obliterate
tissues in neck and clavicle don’t develop properly
presents as large painless lump in anterior triangle of neck

Question 19

Floor of brain case arises from

Answer 19

Paraxial mesoderm

Question 20

Mesenchyme involved in formation of head and neck derived from which germ layers?

Answer 20

Paraxial mesoderm
Lateral plate mesoderm
Neural crest cells
Ectoderm