Head and Neck Embryology

Question 1

what forms the neural tube?

Answer 1

some of the ectoderm in the midline folds

Question 2

what does the neural tube form?

Answer 2

brain and spinal cord

Question 3

what are somites derived from?

Answer 3

paraxial mesoderm

Question 4

what structures do somites form?

Answer 4

axial skeleton and muscles

help in cranial skeleton development

Question 5

how many somites develop

Answer 5

33

Question 6

what are brachial arches?

Answer 6

Series of arches which develop around the future mouth (stomatodeum) and pharynx.

Question 7

what develops from the brachial arches?

Answer 7

face and neck

Question 8

how many brachial arches develop?

Answer 8

In humans 5 branchial arches develop. (6 arches start to develop but arch number 5 disappears so we are left with arches 1,2,3,4 and 6. )

Question 9

What embryological tissues make up the Branchial Arches?

Answer 9

Ectoderm lines the outside
Mesoderm in the middle
(+Neural crest cells)
Endoderm on the inside

Question 10

which nerve forms from the 1st brachial arch?

Answer 10

X mandibular branch of trigeminal

Question 11

which nerve forms from the 2nd brachial arch?

Answer 11

VII facial nerve

Question 12

which nerve forms from the 3rd brachial arch?

Answer 12

IX glossopharyngeal nerve

Question 13

which nerve forms from the 4th brachial arch?

Answer 13

X Superior laryngeal branch of vagus

Question 14

which nerve forms from the 6th brachial arch?

Answer 14

X Recurrent laryngeal branch of vagus

Question 15

name the 5 processes/prominences the face develops from

Answer 15

One frontonasal process
Two maxillary processes
Two mandibular processes

Question 16

what forms the nostril?

Answer 16

Ectodermal thickening (nasal placode) pushes inwards or invaginates to form the nasal pit

Question 17

what forms the philtrum?

Answer 17

The medial nasal process further grows downwards and laterally

Question 18

give the 1st stage in the development of the palate?

Answer 18

Medial nasal process grows downwards and forms philtrum. This forms the primary palate

Question 19

give the 2nd stage in the development of the palate?

Answer 19

From the maxillary processes, two palatine shelves grow inwards

Question 20

give the 3rd stage in the development of the palate?

Answer 20

The palatine shelves meet in the midline to form the secondary palate.

Question 21

if the palate doesn’t fuse properly what occurs?

Answer 21

Cleft lip and palate

Question 22

what forms the flat bones of the cranium?

Answer 22

Membranous bones, formed by membranous ossification calvaria

Question 23

what forms the irregular bones at base of skull?

Answer 23

Bones formed by endochondral ossification

Question 24

what forms the skeleton of face

Answer 24

Partly from branchial arches, and partly from sensory (special sense) capsules

Question 25

what can occur if the fontanelles fuse too early?

Answer 25

Craniosynostosis

Question 26

what is the 1st pharyngeal arch abnormality called?

Answer 26

Treacher Collins syndrome

1st arch forms mandible + some of the ear bones (born deaf)