Embryology

Question 1

Structures formed from the 1st pharengeal arch

Answer 1

Muscles of mastication, Mandible, Incus, Malleolus

Question 2

Structures formed from the 2nd pharengeal arch

Answer 2

Muscles of facial expression, Styloid of temporal bone, Stapes

Question 3

Structures formed from the 3rd pharengeal arch

Answer 3

Stylopharyngeus, Hyoid bone

Question 4

Structures formed from the 4th pharengeal arch

Answer 4

Cricothyyroid, Levator palatine, Constrictirs of the pharynx, Thyroid cartilage, Epiglottis

Question 5

Structures formed from the 6th pharengeal arch

Answer 5

Intrinsic muscles of the larynx, Thyroid cartilage, Arytenoid cartilage, Cricoid cartilage

Question 6

Fate of the 1st pharyngeal pouch

Answer 6

Middle ear

Question 7

Structures that form from the frontonasal prominence

Answer 7

Forehead, Nose, Philtrum

Question 8

Structures that form from the maxillary prominence

Answer 8

Cheeks, Upper jaw, Upper lip

Question 9

Structures that form from the mandibular prominence

Answer 9

Lower jaw, Lower lip

Question 10

Describe the development of the nose

Answer 10

Nasal placodes in the frontonasal prominence sink, Prominences form around them

Question 11

Describe how the intermandibular segement is formed

Answer 11

From fusion of the medial nasal prominences with the maxillary prominence

Question 12

Describe the formation of the palate

Answer 12

Palatine shelves fuse once tongue falls due to growth of the mandible to form secondary palate, Primary palate is from the intermandibular segement

Question 13

Describe the formation of the eyes

Answer 13

Optic placodes moved to the centre by growth of the maxillary prominence then invaginate

Question 14

Describe the formation of the ear

Answer 14

Forced up by growth of the mandible, Auricle develops from the 1st and 2nd pharengeal arches

Question 15

Describe the formation of the pituitary gland

Answer 15

Down growth of forebrain (infundibulum) joins with up growth from oropharynx (Rathke’s pouch)

Question 16

Describe the formation of the tongue

Answer 16

Lateral swellings from the 1st arch over the 1st medial swelling. 2nd medial swelling develops from 2nd 3rd and 4th arch, 3rd arch over goes the 2nd. 4th arch forms the 3rd medial swelling

Question 17

Describe the formation of the thyroid

Answer 17

Begins below the developing tongue, Descends via the thyroglossal duct