Question 1

________ Organ derived from the second pharyngeal pouch and mesenchyme

Accepted Answer

The surface epithelium and lining of the crypts of the palatine tonsils are derived from the endoderm of the second pair of pharyngeal pouches.The mesenchyme that surrounds the pouches differentiates into lymphoid tissue that soon becomes organized into lymph nodules.

Question 2

________ External branchial sinus

Accepted Answer

External branchial (lateral cervical)sinuses are lined with stratified squamous or columnar epithelium;they are surrounded by a muscular wall.Thus,by pulling the skin inferiorly,it is possible to palpate the firm sinus as it extends superiorly.

Question 3

________ Superior parathyroid gland

Accepted Answer

The dorsal bulbar part of each fourth pharyngeal pouch develops into a superior parathyroid gland.They come to lie on the dorsal surface of the thyroid gland.

Question 4

________ Internal branchial sinus

Accepted Answer

Internal branchial sinuses open into the pharynx.They commonly are derived from a remnant of the second pharyngeal pouch;hence,they typically open into the intratonsillar fossa,the remains of the opening into the second pharyngeal pouch.

Question 5

________ Inferior parathyroid gland

Accepted Answer

The dorsal bulbar part of each third pharyngeal pouch differentiates into a parathyroid gland.These glands migrate caudally with the thymus,which develops from the ventral portions of this pair of pharyngeal pouches.Hence,the parathyroid glands derived from the third pair of pouches come to lie further caudally than those from the fourth pair of pouches.Because of this descent,sometimes the inferior parathyroid glands are located in other than their normal position;that is,they may be drawn into the thorax by the descent of the thymus.

Question 6

________ Forms half of the thymus

Accepted Answer

The ventral portions of the third pair of pharyngeal pouches fuse and give rise to the primordium of the thymus.This thymic mass is invaded by mesenchymal cells that break up the gland into lobules.The thymic corpuscles (Hassall corpuscles)appear to be derived from the endodermal epithelium.The origin of the thymocytes is controversial,but they are believed to be mesenchymal.

Question 7

________ Gives rise to the pharyngotympanic tube

Accepted Answer

The tubotympanic recess gives rise to the epithelium and glands of the pharyngotympanic tube.The bony wall in its posterior third and the remaining cartilaginous wall are derived from the surrounding mesenchyme.

Question 8

________ Tubotympanic recess

Accepted Answer

The epithelium and the glands of the pharyngotympanic tube are derived from the elongated tubotympanic recess,the expanded first pharyngeal pouch.This recess also gives rise to the tympanic cavity and antrum.The connective tissue and cartilaginous parts of the tube are derived from the mesenchyme surrounding the tubotympanic recess.

Question 9

________ Palatine tonsil

Accepted Answer

The palatine tonsils are derived from the endoderm of the second pair of pharyngeal pouches and the associated mesenchyme.The endoderm of the pouches gives rise to the surface epithelium and the lining of the crypts of the tonsil.The mesenchyme around the developing crypts differentiates into lymphoid tissue.

Question 10

________ Derived from the second pharyngeal groove and cervical sinus

Accepted Answer

External branchial sinuses (lateral cervical sinuses)are uncommon.Almost all of those that open on the side of the neck result from failure of the second pharyngeal groove to obliterate.The sinuses typically open on the inferior one third of a line that runs from the auricle of the ear along the anterior border of the sternocleidomastoid muscle to the jugular notch.There often is an intermittent discharge of mucus from the opening,resulting from infection of the sinus.

Question 11

________ Tubotympanic recess

Accepted Answer

The tubotympanic recess becomes the pharyngotympanic tube,tympanic cavity,and antrum.Its epithelium forms the internal layer of the tympanic membrane.

Question 12

________ Internal branchial sinus

Accepted Answer

Internal branchial sinuses opening into the pharynx are uncommon.Because they almost always open into the intratonsillar fossa or near the palatopharyngeal arch,these sinuses usually result from partial persistence of part of the second pharyngeal pouch.These pouches commonly give rise to the epithelium and the lining of the crypts of the palatine tonsils.

Question 13

________ Thymus

Accepted Answer

The elongated ventral parts of the third pair of pharyngeal pouches migrate medially and fuse to form the primordium of the thymus.Development of the thymus is not complete at birth;it continues to grow and reaches its greatest size at puberty.Thereafter it becomes very small and is difficult to locate.

Question 14

________ Gives rise to ultimopharyngeal body

Accepted Answer

The ventral portions of the fourth pharyngeal pouch give rise to the ultimopharyngeal body.If present,the fifth pair of pouches may also contribute to the formation of these bodies.The ultimopharyngeal bodies later fuse with the thyroid gland and are represented by cells called C or parafollicular cells.These cells produce calcitonin,an important hormone concerned with calcium metabolism.

Question 15

________ Derived from the second and third pharyngeal arch cartilages

Accepted Answer

The hyoid bone develops by endochondral ossification of the ventral ends of the second and third pharyngeal arch cartilages.The second arch cartilages give rise to the lesser cornua and the superior part of the body,and the third arch cartilages give rise to the greater cornua and the inferior part of the body of the hyoid bone.

Question 16

________ Internal and external carotid arteries

Accepted Answer

Sinuses and fistulas ascend through the subcutaneous tissue and the platysma muscle and between the external and internal carotid arteries.

Quiz 9: Pharyngeal Apparatus

________ Organ derived from the second pharyngeal pouch and mesenchyme

________ External branchial sinus

________ Superior parathyroid gland

________ Internal branchial sinus

________ Inferior parathyroid gland

________ Forms half of the thymus

________ Gives rise to the pharyngotympanic tube

________ Tubotympanic recess

________ Palatine tonsil

________ Derived from the second pharyngeal groove and cervical sinus

________ Tubotympanic recess

________ Internal branchial sinus

________ Thymus

________ Gives rise to ultimopharyngeal body

________ Derived from the second and third pharyngeal arch cartilages

________ Internal and external carotid arteries