Head and Neck II

Question 1

When do pharyngeal arches begin developing?

Answer 1

Around 3rd week of gestation in domestic animals

Question 2

What are invaginations of ectoderm formed between adjacent arches called?

Answer 2

Pharyngeal grooves or clefts

Question 3

What produces pharyngeal pouches?

Answer 3

Endoderm of the expanding foregut evaginates between the arches

Question 4

What does contact of cleft and pouches form?

Answer 4

Pharyngeal membranes

Question 5

What makes up the pharygneal complex?

Answer 5

Pharyngeal Arches

Clefts

Pouches

Question 6

What 3 things are associated with each pharyngeal arch?

Answer 6

Aortic arch artery

Muscle component

Branch of Cranial nerve

Question 7

What is somitomere?

Answer 7

Give off myogenic cells, which are very migratory. Allow for muscle formation in face and pharynx

Question 8

What do aortic arch arteris form from?

Answer 8

Mesoderm within each arch

Question 9

What do aortic arch arteries form?

Answer 9

Vascular link to aortic sac and paired dorsal aortae

Question 10

What do cranial-caudal body folding result in?

Answer 10

Cranial parts of dorsal aortae bending and forming aortic arches lateral to the foregut

Question 11

Which aortic arch develops first?

Answer 11

Anterior - forms and then remaining develop sequentially

Question 12

What is the second or hyoid arch?

Answer 12

Reichert’s cartilage - gives rise to stapes of middle ear. Bones of hyoid apparatus

Question 13

What is third arch

Answer 13

Other bones of hyoid apparatus, stylopharyngeus muscle which dilates pharynx

Question 14

What are 4th-6th arches?

Answer 14

Laryngeal cartilages

Question 15

What doe endodermal epithelium of pouches differentiate into?

Answer 15

Components of lymphatic and endocrine system

Question 16

In the late fetal period, what does second pouch contain?

Answer 16

Aggregate of tissue - palatine tonsil (lymphatic tissue)

Question 17

From where do parathyroid glands develop?

Answer 17

Dorsal parts of the 3rd and 4th pouches

Question 18

Slide 9

Question 19

What occurs with caudal migration of thyroid?

Answer 19

Parathyroid IV glands become embeded into thyroid gland

Question 20

Where are parathyroid III gland located?

Answer 20

Caudal to thyroid

Question 21

What does Parathyroid hormone do?

Answer 21

Increases blood calcium levels

Question 22

What is structure of thymus initially?

Answer 22

Two separate tubular structures

Question 23

What occurs as separate tubular structures of thymus extend caudallY/

Answer 23

They eventually fuse in midline and become associated with pericardium

Question 24

What does thymus produce?

Answer 24

Thymic hormones responsible for making competent T-lymphocytes involved in cellular immune responses

Question 25

What is the 1st pouch?

Answer 25

Auditory (Eustachian) tubes of ear and tympanic cavities

Question 26

What occurs in first pouch of horses?

Answer 26

A diverticula of auditory tubes lead to development of guttural pouches

Question 27

What are guttural pouches?

Answer 27

Mucus secreting sacs that communicate with pahrynx

Question 28

What is first cleft?

Answer 28

Ectoderm of cleft gives rise to epithelial lining of external auditory meatus

Question 29

What forms cervical sinus?

Answer 29

Second arch extends caudally over 2nd and 3rd clefts. A transient structure lined by ectoderm then forms cervical sinus

Question 30

Where does tongue develop?

Answer 30

Develops on floor of oral cavity from portion of 1st pharyngeal arch.

Question 31

What are the 3 elevations that occur at the region of the 1st arch due to underlying mesoderm grwoth?

Answer 31

Two lateral lingual swellings One tuberculum impar

Question 32

What develops at 2nd pharyngeal arch with regards to tongue?

Answer 32

Copula

Question 33

With regards to tongue what develops at 3rd and 4th arches?

Answer 33

Hypopharyngeal eminence forms