The development of the face

Question 1

What do each of the four banchial arches contain?

Answer 1

each has an arch cartilage, a specific cranial nerve, an aortic arch, and a core of mesennchymal cells of mesodermal and neural crest origin

Question 2

What do the neural crest cells in the cranial region do?

Answer 2

They have potential to develop into a variety of cells and tissues and to direct the development of the branchia arches.

Question 3

What are some of the factors that determine what cranial neural crest cells do?

Answer 3

THe area of the developing brain, genetic factors, and signaling molecules.( permissive and inhibitory factors and positive and negative chemotaxis)

Question 4

What are the three initial segments that the cranial end of the neural tube is divided into? Which segment is relevant to the development of the branchial arches? what are the subsections divided into.

Answer 4

Rhombencephalon (hindbrain) related to branchial arches and are separated further into rhombomeres.
Mesencephalon (midbrain)
Prosencephaln (Forebrain)

Question 5

What are the two main processes of the first branchial arch?

Answer 5

The mandibular and maxillary processes.

Question 6

What is the prominence above the first branchial arch? What part of the brain does it come from

Answer 6

The frontonassal prominence with pair nassal placodes. forebrain

Question 7

What is the first facial feature to form?

Answer 7

The mandibular process

Question 8

What is the cartilage that forms the infrastructure for the formation of the mandible?

Answer 8

Meckel’s Cartilage

Question 9

What type of bone formation happens in the head and face

Answer 9

intermembranous

Question 10

What is the cranial nerve that develops with the first arch?

Answer 10

The trigeminal nerve (V)

Question 11

What structures and nerves are involved in the second arch?

Answer 11

The styloid process and stapes and the facial nerve (VII)

Question 12

What nerve is associated with the third arch?

Answer 12

The glossopharyngeal (IX)

Question 13

What nerve is associated with the fourth arch?

Answer 13

The vagus (X)

Question 14

What is the maxillary process of the first arch a precursor to?

Answer 14

The upper jaw, facial bones, and upper lip

Question 15

What is the groove between the lateral nasal prominence and the maxillary prominence called? what does it eventually turn into?

Answer 15

The nasolacrimal groove. turns into the lacrimal gland and nasolacrimal duct

Question 16

Describe the development of the nasolacrimal groove and issues that can occur

Answer 16

The groove forms a thick cord which is transformed into the lacrimal sac and the nasolacrimal duct. Insufficient mesenchymal cells in the maxillary process and/or the localized absence of an ectodermal chord results in the presence of an oblique cleft between the medial margin of the eye and the upper lip.

Question 17

How is the bridge of the nose formed?

Answer 17

By the fusion of the medial nasal processes cranially?

Question 18

What does the cadual fusion of the medial nasal prominences from?

Answer 18

The intermaxillary segment which becomes the philtrum of the upper lip and the primary palate (posterior tip is where the incisor foramen is)

Question 19

how does the secondary palate form?

Answer 19

By the fusion of bilateral palatine processes projected from the inferior aspect of the maxillary processes. Myogenic cells in the posterior portion form the musculature of the soft palate.

Question 20

What causes a cleft lip?

Answer 20

The failure of the maxillary process to fuse with the intermaxillary segment.

Question 21

What causes a anterior cleft palate?

Answer 21

The failure of the lateral palatine process to fuse with the primary palate

Question 22

What causes a posterior cleft palate?

Answer 22

The failure of the lateral palatine process to fuse with each other, the primary palate and the nasal septum.

Question 23

Describe the composition of the tongue with respect to its origins from the branchial arches

Answer 23

The anterior 2/3 is from the first arch and thus innervated by the Trigeminal nerve. A section of the tongue is a second arch derivative but ends up getting buried but explains the involvement of the facial nerve (Chorda tympani). The posterior 1/3 of the tongue comes from the 3rd arch and thus the glossopharyngeal nerve. The root of the tongue is the fourth arch and has some contribution from vagus.

Question 24

What do the third and fourth arch of the tongue form?

Answer 24

The hypocranchial eminence

Question 25

What is the border between the anterior 2/3 and posterior 1/3 of the tongue? What is at its apex? What is derived from this area.

Answer 25

The terminal sulcus and at the apex is the foramen caecum which will form the thryoglossal duct and ultimately the thyroid gland

Question 26

Where does the thyroid gland originate form?

Answer 26

from the thyroid diverticulum which originates from thyroglossal duct from the foramen cecum. (invagination of oral endoderm) descends down the level of cricoid cartilage. neural crest cells then migrate from the 5th branchial pouch and become parafollicular cells which produce calcitonin.

Question 27

What structure is the remnant of the thyroglossal duct?

Answer 27

The pyramidal lobe of the thyroid gland.

Question 28

What does the first pharyngeal pouch form?

Answer 28

The eustachian tube and the cavity of the middle ear

Question 29

Where are the palatine tonsils formed from?

Answer 29

The endoderm of 2nd pouch along with the mesoderm of the 2nd and 3rd pahrygeal arches contribute to the formation of the palatine tonsil

Question 30

What does the 3rd pharyngeal pouch form?

Answer 30

derivatives of the inferior parathyroid glands and the thymus

Question 31

What does the 4th pharyngeal pouch form?

Answer 31

gives rise to the superior parathyroid glands

Question 32

What is the parotid gland formed from?

Answer 32

The ectoderm between the maxillary and mandibular processes

Question 33

What are the submandibular and sublingual glands formed form?

Answer 33

The mesoderm of the first arch

Question 34

Where is the pinna or auricle of the external ear derived from?

Answer 34

The mesenchyme portion of the first and second branchial arches bordering the first branchial cleft. which become the auricular hillocks. deformations of the ear may be accompanied by further deformations related to 1st and 2nd arch derivatives

Question 35

What layers of embryonic tissue is the tympanic membrane made of?

Answer 35

ALLLLL!

Question 36

what is the medial swelling of the distal tongue called?

Answer 36

The tuberculum impar

Question 37

Where is the thymus formed from?

Answer 37

The endodermal cells from the 3rd pharyngeal pouch

Question 38

Where is the middle ear and eustachian tube derived from?

Answer 38

The first branchial pouch

Question 39

What primary cell layer does the tongue originate from?

Answer 39

endoderm