Embryology

Question 1

When does the Human face development begins

Answer 1

at the 4th week IUL

Question 2

When does the external face development is completed

Answer 2

By the end of the 6th week, however it doesn’t mean it is now its distinctive, but that all the features are there

Question 3

How does development start?

Answer 3

With the growth of the mesenchymal tissue (connective tissue) of the embryo, and will result in formation of the pharyngeal system or apparatus.

Question 4

What does the pharyngeal system consist of?

Answer 4

1-arches
2-clefts (from the ectodermal side)
3-pouches (from the endodermal)

Question 5

what does each pharyngeal arch contain or has?

Answer 5

each arch is lined from the outside with ectoderm, and from the inside with endoderm, and between them is the mesoderm which contains cartilage, artery, and nerve.

Question 6

How many pharyngeal arches are there?

Answer 6

There are 6 pharyngeal arches, but the 5th one regress before birth, so in reality we only have 5 (1,2,3,4,6)

Question 7

Define the pharyngeal arches?

Answer 7

-They are embryonic structure found in the developing embryo; they are bilateral swellings that grow from the cephalic(head) of the neural crest

-each arch is innervated by a specific cranial nerve.

-each pharyngeal arch will have one or more crania nerve, and they aren’t arranged respectively (hence 1st arch=5th cranial nerve)

Question 8

What does the first pharyngeal arch consist of?

Answer 8

two parts dorsal and ventral portions

Question 9

The dorsal portion of the first pharyngeal arch gives rise to the:

Answer 9

1-maxillary process,
2- anterior portion of palate,
3-zygomatic bone, and
4-part of the temporal bone.
5-It is also associated with the maxillary cartilage which give rise to the incus of the ear

Question 10

The ventral portion of the first pharyngeal arch gives rise to the:

Answer 10

1-Meckels cartilage which give rise to the
a-malleus of the ear
b-sphenomandibular ligament
c-it also shares the formation of the mandible part the carries the incisors

Question 11

What is the blood supply of the first pharyngeal arch?

Answer 11

the terminal portion of the maxillary artery, which is a prat of the external carotid artery.
-So, maxillary artery supplying maxilla and mandible

Question 12

-Inferior alveolar artery is a branch of?

Answer 12

the maxillary artery

Question 13

what is the innervation of the 1st arch

Answer 13

Trigeminal

Question 14

The trigeminal nerve is mixed, what are its motor branches?

Answer 14

1-muscle of mastication (Masseter.Temporalis.Lateral and Medial pterygoid.
2-mylohyoid muscle
3-ant. belly of digastric
4-tensor veli palatani
5-tensor tympani

Question 15

The trigeminal nerve is mixed, what are its sensory branches?

Answer 15

1-skin of the face
2-lining of the mouth and nose
3-general sensation of anterior 2/3rd of the tongue (cold, heat, pain)

Question 16

What is cartilage component associated with the second pharyngeal arch?

Answer 16

Reichart’s cartilage

Question 17

Reichart’s cartilage give rise to ?

Answer 17

1-the last bone of the ear (stapes)
2-styloid process
3-stylohyoid ligament
4-upper body hyoid bone
5-lesser horn of the hyoid bone

Question 18

what is the innervation of the 2nd arch

Answer 18

Facial never VII

Question 19

The facial nerve is mixed, what are its motor branches?

Answer 19

Motor part innervates all the muscular derivates of the 2nd arch:
1-the muscle of facial expression
2-stapedius
3-stylohyoid
4-platysma
5-posterior belly of digastric

Question 20

The facial nerve is mixed, what are its sensory branches?

Answer 20

Chorda tympani (taste sensation of the anterior 2/3rd of the tongue)

Question 21

What is the blood supply of the second pharyngeal arch?

Answer 21

1-Stapedial artery (which connects arteries (middle meningeal, internal carotid, internal maxillary) during embryonic stage and then it regresses before birth

2-Hyoid artery

Question 22

What is the blood supply of the third pharyngeal arch?

Answer 22

1-common carotid artery
2- The proximal portion of the internal carotid artery

Question 23

What is cartilage component associated with the third pharyngeal arch?

Answer 23

The cartilaginous component is less complex than the first two and only gives rise to
1-greater horn of the hyoid
2-lower body of the hyoid
3- stylopharyngeal ligament

Question 24

what is the innervation of the 3rd arch

Answer 24

glossopharyngeal nerve (IX)

Question 25

What is the blood supply of the fourth pharyngeal arch?

Answer 25

The vascular derivatives differ between the left and right sides

Right - proximal portion of the subclavian artery
Left-aortic arch

Question 26

What is cartilage component associated with the fourth pharyngeal arch?

Answer 26

laryngeal cartilage namely the thyroid, corniculate, cuneiform cartilages

Question 27

what is the innervation of the 4th arch?

Answer 27

Superior laryngeal branch of the vagus nerve, innervates
1-constrictors of the pharynx
2-levator palatani
3-cricothyroid
4- and the root of the tongue.

Question 28

What is the blood supply of the sixth pharyngeal arch?

Answer 28

The vascular derivatives differ between the left and right sides
Right – proximal portion of the pulmonary artery
Left- ductus arterious

Question 29

what is the innervation of the 6th arch?

Answer 29

recurrent laryngeal branch of vagus nerve, which supply

1-Motor -intrinsic muscles of the larynx with the exception of cricothyroid
2-Sensory - general sensation of the pharynx, larynx, esophagus, tympanic membrane, external auditory meatus, and part of the external ear,
3-and taste to the epiglottis
4-gag reflex

Question 30

which pharyngeal cleft give rise to anything? and what is it?

Answer 30

Only the 1st cleft give permanent structure which is the
-External auditory meatues

Question 31

what do the 2nd, 3rd, and 4th pharyngeal cleft give rise to?

Answer 31

they only form temporary cervical sinuses, which even these are obliterated by the growing second arch.

Question 32

what will happen if the pharyngeal clefts are not obliterated by the growing 2nd pharyngeal arch?

Answer 32

they can persist into adulthood as pharyngeal cysts, which is located laterally on the neck, just anterior to the sternocleido mastoid muscles

Question 33

treatment of pharyngeal cysts

Answer 33

-in case of infection just surgically remove it.

Question 34

how many Pharyngeal pouches?

Answer 34

There are five pairs of pouches, only four give rise to structure in the adult

Question 35

what are the given structure from the pharyngeal pouches?

Answer 35

1-First pouch-
Eustachian tube and middle ear cavity
2-Second pouch-
Lining of the palatine tonsils
3-Third pouch
Dorsal -inferior parathyroid glands
ventral -thymus gland
4-Fourth pouch
Dorsal-superior parathyroid glands
Ventral - ultimobranchial body

Question 36

cartilage of the 6th pharyngeal arch?

Answer 36

laryngeal cartilages

Question 37

when does the Facial formation in the fetus occurs ?

Answer 37

between 5th and 10th week IUL