Session 5- Development of the Head, Neck and Face

Question 1

what are the pharyngeal arches

Answer 1

sequence of ridges that form in the lateral walls of the embryonic pharynx towards the cranial end of the neural tube

Question 2

when do the pharyngeal arches become apparent

Answer 2

4 weeks in

Question 3

which clefts remain and what do they become

Answer 3

first - becomes external auditory meatus

Question 4

what forms the auricle

Answer 4

swellings which form around the entrance to the meatus

Question 5

what covers the external surface of the pharyngeal arches

Answer 5

ectoderm

Question 6

what covers the internal surface of the pharyngeal arches

Answer 6

endoderm

Question 7

how many arches are there

Answer 7

theoretically 6 but the 5th doesnt form in humans

Question 8

whuch arch is biggest

Answer 8

1st and they get progressively smaller in size from 1-6

Question 9

what is assciated with each arch

Answer 9

cartilage
artery
nerve

Question 10

what does the cartilage bar become

Answer 10

skeletal element of the head and neck

Question 11

what is teh cartilagenous bar in the 1st bar known is

Answer 11

meckles cartilage

largest

Question 12

what does the Meckel’s cartilage become- derived from 1st arch

Answer 12

mandible
malleus
incus

Question 13

what do the 4th and 6th arches give rise to

Answer 13

thyroid
arytenoids
cricoids

Question 14

which cranial nerves associate with the pharyngeal arches

Answer 14

V
VII
IX
X

Question 15

What is arch 1 associated with

Answer 15

V

Question 16

What nerve is arch 2 associated with

Answer 16

VII

Question 17

What is arch 3 associated with

Answer 17

IX

Question 18

What is arch 4 associated with

Answer 18

vagus- superior laryngeal

Question 19

What nerve arch 6 associated with

Answer 19

vagus- recurrent laryngeal nerve

Question 20

what muscles are derived from the first arch

Answer 20

muscles of mastication

Question 21

what muscles are derived from the second arch

Answer 21

Muscles of facial expression

Question 22

what muscles are derived from the third arch

Answer 22

stylopharyngeus - muscle of pharynx

Question 23

what muscles are derived from the 4-6arch

Answer 23

constrictor muscles of pharynx and muscles of soft palate
muscles of the larynx
striated muscle of upper oesophagus

Question 24

where does the facial skeleton arise from

Answer 24

frontonasal prominene

Question 25

what structure arises from pouch 1

Answer 25

pharyngotympanic (eustachian) tube and middle ear cavity

Question 26

what structure arises from pouch 2

Answer 26

palatine tonsil

Question 27

what structure arises from pouch 3

Answer 27

inferior parathyroid | thymus

Question 28

what structure arises from pouch 4

Answer 28

superior parathyroid | c cells of thyroid

Question 29

what are the 5 building blocks of the face

Answer 29

frontonasal prominence 2 maxillary prominences 2 mandibular prominences

Question 30

what is teh frist evidence of face development

Answer 30

stomadaeum - a depression in the ectoderm on the ventral aspect of the head which is teh site of future mouth

Question 31

how is the face created

Answer 31

the 5 prominences fold around the stomadaeum to create the face

Question 32

what does the frontonasal prominence go on to form

Answer 32

forehead bridge of nose upper eyelids centre of upper lip

Question 33

what do teh 2 lateral paired maxillary prominence form

Answer 33

middle third of face upper jaw most of the lip and sides of the nose

Question 34

wht do the paired mandibular prominences form

Answer 34

lower third of the face - lower jaw and lip

Question 35

what is the first evidence of nose formation and how does the nose form

Answer 35

appearance of 2 ectodermal thickenings which are the nasal placdes wither side of the midline on the ventrolateral aspect of the frontonasal prominence the nasal placodes invaginate and form deep pits the nasal pits with the entrance of each pit being the future nostril

Question 36

what is a placodeo

Answer 36

an area of ectoderm that starts to thicken and differentiate itself from its surrounding tissue to give rise to sensory structures

Question 37

oronasal membrane

Answer 37

a thin sheet of cells between the stomadaeum and deepening nasal pits which disappears and the oral and nasal cavities become one continous space

Question 38

how does the palate develop

Answer 38

medial nasal prominences merge in the midline separating the nostrils form the mouth this forms the philtrum of upper lip and a small midlne component of palate a palatal shelf grows from each maxillary prominence towards the midline they fuse with each other and with the primary palate fusion creates the secondary palate and separates the nasal cavity from oral cavityv

Question 39

why do clefts develop

Answer 39

failure of fusion betwen tructures of the developing face

Question 40

how does a clefy lip arise

Answer 40

failure of the fusion of the medial nasal prominence and maxilllary prominence

Question 41

how does a cleft palate arise

Answer 41

failure of fusion of the palatal shelves - hard palate - to meet in the midline

Question 42

aetiology of clefts

Answer 42

both genetic and environmental fatcors

Question 43

why does fetal alcohol syndrome present with low set ears

Answer 43

alcohol arrests the ascent of ears

Question 44

at innervates the anterior 2/3 of the tngue

Answer 44

general sensation from trigeminal | taste from facial

Question 45

posterior 1/3 of tongue innervation

Answer 45

general sensation and taste from glossopharyngeal

Question 46

where does the thyroids develop fro

Answer 46

thyroid diverticulum whihc originates from the foramen caecum therefore tongue

Question 47

from which pharyngeal arch are the maxilary and mandibular prominences formed

Answer 47

first

Question 48

what happens to the pharyngeal grooves or clefts in the devloping embryo

Answer 48

all are obliterted except 1 because the secon pharyngeal acrh grows caudally covering all the other pharygeal arches and tehir grooves this creates a small space called the cervical sinus which eventually fuses closed as the grooves disappear

Question 49

outline how a branchial cyst develops

Answer 49

incomplets fusion of the second pharyngeal arch iver the other arches/ grooves allows persistence of the cervical sinus an open channel for communication between the sinus and the external environment may persist this gives rise to a branchial sinus

Question 50

what predisposes a branchial cyst

Answer 50

infection minor trauma this causes the cyst to swell making it become apparent

Question 51

how do branchial cysts present

Answer 51

smooth non tender soft masses along the anterior border of teh SCM