head and neck embryology

Question 1

what does the neck develop from?

Answer 1

brnchial/pharyngeal arches

Question 2

what does the face develop from?

Answer 2

5 mesenchymal processes/prominences

Question 3

where does the skull develop from?

Answer 3

develops from the mesenchyme in the head region of developing embryo

Question 4

what is mesenchyme?

Answer 4

embryonic connective tissue

Question 5

what is a ball of cells called?

Answer 5

blastula

Question 6

why do 2 areas not have mesoderm?

Answer 6

sites of future mouth and anus

Question 7

ectoderm in the midline folds down to form?

Answer 7

neural tube -> brain and spinal chord

Question 8

cells at the crest of this neural fold seperate to form

Answer 8

neural crest cells

Question 9

what do neural crest cells give rise to?

Answer 9

wide variety of structures

Question 10

what are somites derived from?

Answer 10

from paraxial mesoderm and form structures like the axial skeleton and muscles

Question 11

how many somites develop in human embryos

Answer 11

33

Question 12

what do somites help with in the head region of the embryo?

Answer 12

help in cranial skeleton development

Question 13

what are the pharyngeal/branchial arches?

Answer 13

series of arches which develop around the future mouth and pharynx

Question 14

what embryological tissures make up the branchial arches?

Answer 14

ectoderm
mesoderm
endoderm
skeletal element
artery 
nerve

Question 15

function of the ectoderm

Answer 15

lines the outide and forms clefts in between arches

Question 16

function of mesoderm

Answer 16

in middle plus neural crest cells

contrinutes to cartilage and muscle

Question 17

function of the endoderm

Answer 17

forms inside and forms pouches in between the arches

Question 18

nerves of the 1st arch

Answer 18

mandibular branch of trigeminal V

Question 19

nerves of the 2nd arch

Answer 19

facial nerve VII

Question 20

nerves of the 3rd arch

Answer 20

glossopharyngeal n IX

Question 21

nerves of the 4th arch

Answer 21

superior laryngeal branch of vagus X

Question 22

nerves of the 6th arch

Answer 22

recurrent laryngeal branch of the vagus X

Question 23

what nerve is all the muscles of the face innervated by?

Answer 23

VII cranial nerve - facial nerve

therefore all these muscles developed from the 2nd branchial arch

Question 24

what nerve is the digastric muscle innervated by?

Answer 24

anterior belly innervated by mandibular division of the trigeminal nerve V3

posterior belly innervated by facial nerve

Question 25

what are other important structures developing from the branchial arches?

Answer 25

tongue thyroid gland parathyroid gland part of the pituitary gland

Question 26

the face develops from 5 processes. What are these 5 processes?

Answer 26

One frontonasal process (from mesenchyme superior to future mouth) Two maxillary processes ( from maxillary part of 1st branchial arch mesoderm) Two mandibular processes (also 1st arch mesoderm) Important for understanding of how congenital facial defects (clefts) develop

Question 27

what is stage 1 of development of palate

Answer 27

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

Question 28

stage 2 of development of palate

Answer 28

2:From the maxillary processes, two palatine shelves grow inwards

Question 29

stage 3 of development of palate

Answer 29

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

Question 30

how are membranous bones from the cranium formed?

Answer 30

membranous ossifiaction calvaria

Question 31

what type of bones is present on the base of skull?

Answer 31

irregular bones

Question 32

how are irregular bones formed?

Answer 32

formed by endochondral ossification

Question 33

how is the viscerocranium formed?

Answer 33

partly from branchial arches and partly from sensory capsules

Question 34

how is the base of the skull formed

Answer 34

Mesenchyme around notochord is derived predominantly from neural crest cells Preform in cartilage first later then ossify

Question 35

what are sensory capsules?

Answer 35

derived from mesoderm of somites in head and neck region.

Question 36

function of sensory capsules

Answer 36

these preform in cartilage and ossify to form bones around the sense organs

Question 37

what is an example of a 1st pharyngeal arch abnormality?

Answer 37

treacher collins syndrome