Pharyngeal Arches,pouches,clefts.

Question 1

LOOK AT THE OBJECTIVES

Question 2

In which week do Pharyngeal arches develop?

Answer 2

Week 4

Question 3

What role do neural crest cells play in pharyngeal arches?

Answer 3

Contribute to most skeletal and connective tissues of head and neck

Question 4

Describe the pharyngeal system?

Answer 4

It consists of 6 pairs of pharyngeal arches separated by endodermally lined pouches and ectodermly lined clefts.

Question 5

What does each arch consist of?

Answer 5

Nerve,artery and cartilage

Question 6

List the three components which make up the pharyngeal arches?
What does each component form?

Answer 6

1.Ectoderm-cleft
2.Mesoderm + neural crest cells-arches
3.Endoderm-pouch

Question 7

How many pharyngeal arches develop in an embryo?And which if these does not give rise to any derivates?

Answer 7

1.6 pairs
2.the 5th pair

Question 8

At what stage of development does the tongue develop?

Answer 8

Week 4

Question 9

From which pharyngeal arch does the anterior two thirds of the tongue develop?

Answer 9

The first pharyngeal arch

Question 10

Which pharyngeal arches are responsible for the formation of the posterior third of the tongue?

Answer 10

The pharyngeal arches 2 and 3

Question 11

What are the derivatives of the first pharyngeal arches?

Answer 11

refer to Handout

Question 12

What are the prominence of the pharyngeal arch 1?

Answer 12

Maxilla,mandible and zygomatic bone

Question 13

What is the cartilage of the 1st pharyngeal arch and what does it give rise to?

Answer 13

1.Meckel’s Cartilage
2.Malleus,Incus,anterior ligament of the malleus and the sphenomandibular ligament

Question 14

Muscles of the 1st pharyngeal arch?

Answer 14

1.Muscles of mastication(temporal is,masseter and pterygoids),mylohyoid, tensor tympani

Question 15

Nerve of the 1st pharyngeal arch.

Answer 15

Trigeminal nerve

Question 16

Which pharyngeal arches are responsible for the formation of the three bony ossicles of the ear?

Answer 16

The first and second pharyngeal arches

Question 17

What does the first pharyngeal pouch form?

Answer 17

Eustachian tube,tympanic membrane +cavity and Temporal bone

Question 18

What does the first pharyngeal groove give rise to?

Answer 18

External acoustic meatus

Question 19

What does the tubotympanic recess give rise to?

Answer 19

The tympanic cavity and Eustachian tube.

Question 20

What happens to the other pharyngeal clefts?

Answer 20

The second arches overgrown the clefts and they normally disappear giving rise to the cervical sinus

Question 21

What do each of the pouches form?

Answer 21

1-Eustachian tube,tympanic cavity and membrane
2-Palatine tonsils
3-Parathyroid glands(inferior) and thymus
4 -superior parathyroid glands and parafollicular thyroid cells(Ultimobranchial body)

Question 22

What is the name of the cartilage of the second pharyngeal arch?And what does it give rise to?

Answer 22

1.Reichert’s Cartilage
2.Stapes,the upper body &lesser Cornu of the hyoid bone,the styloid process of the temporal bone,Stylohyoid ligament

Question 23

Muscles of the 2nd pharyngeal arch?

Answer 23

Platysma,muscles of facial expression,Stylohyoid and stapedius

Question 24

Nerve and artery of the 2nd pharyngeal arch?

Answer 24

1.Facial nerve
2.Stapedial artery

Question 25

What does the 2nd pharyngeal pouch give rise to?

Answer 25

Palatine tonsils

Question 26

What does the tubotympanic recess contribute to?

Answer 26

The tympanic cavity and Eustachian tube

Question 27

What does the the third pharyngeal arch form?

Answer 27

Lower body of hyoid and greater Cornu of hyoid bone

Question 28

Muscles of the 3rd pharyngeal arch?

Answer 28

Stylopharyngeus and Superior and middle pharyngeal constrictors

Question 29

Nerve and artery of the 3rd pharyngeal arch?

Answer 29

1.Glossopharyngeal arch 2.Common carotid artery and the proximal portions of the internal and external carotid canal

Question 30

Which pharyngeal arches are responsible for the formation of the three bony ossicles of the ear?

Answer 30

1 and 2

Question 31

What does the 3rd pharyngeal pouch give rise to ?

Answer 31

Inferior parathyroid glands Thymus gland

Question 32

What does the thyroid gland develop as?

Answer 32

Diverticulum from the foramen cecum.

Question 33

What do the 4th and 6th pharyngeal cartilages form?

Answer 33

They fuse to form laryngeal cartilages

Question 34

What does the fourth arch give rise to? Muscles,nerve and artery?

Answer 34

Muscles-cricothyroid,inferior pharyngeal constrictors Nerve:Superior laryngeal branch of the Vagus nerve Artery: Right Subclavian and aortic arch

Question 35

What does the 4th pouch give rise to?

Answer 35

The superior parathyroid glands and the parafollicular thyroid cells(ultimobranchial body)

Question 36

What does the 6th pharyngeal arch give rise to? Muscles,nerves and artery?

Answer 36

1.Muscles-remaining intrinsic laryngeal musculature 2.Nerve -Recurrent laryngeal nerve branch of vagus nerve 3.Artery-pulmonary artery and ductus arteriosus

Question 37

What nerves innervate muscles derived from pre optic somites

Answer 37

Occulomotor,trochlear and Abducens

Question 38

Which nerve innervates muscles derived from occipital somites?

Answer 38

Hypoglossal nerve

Question 39

Where do bronchial cysts develop? And where are most of them found?

Answer 39

1.Anterior border of the stercleidomastoid muscle 2.Most are found inferior to angle of mandible

Question 40

In which age group are the branchial cysts usually seen and what do they represent?

Answer 40

1.Adulthood 2.Remnants of cervical sinus/second pharyngeal clef

Question 41

What are branchial vestiges?And where are they located?

Answer 41

1.Cartilaginous or bony remnants 2.anterior to inferior third of SCM muscle

Question 42

What is a first arch syndrome? It And what causes it?

Answer 42

Various congenital anomalies of eyes,ear,mandible and palate. Migration of neural crest cells into the pharyngeal arch is implicated

Question 43

What are the two manifestations of first syndrome arch syndrome?

Answer 43

1.Treacher Collins Syndrome 2.Pierre Robin Syndrome

Question 44

Where is the thyroid gland located?

Answer 44

Endoderm of the floor primitive pharynx between 1&2nd pharyngeal arches

Question 45

Describe its descend?

Answer 45

It descends as a bilobed diverticulum from the foramen cecum around the 4th week and migrates anterior to the hyoid bone and descends into the inferior aspect of the neck by the 7th-8th week

Question 46

What are the anomalies/tissue deficiencies of Treacher Collins Syndrome?

Answer 46

1.underdevelopment of zygomatic bones of the face,defects of the lower eyelids,external ear deformations

Question 47

What are the manifestations of Pierre Robin Syndrome?

Answer 47

Hypoplasia of the mandible,cleft palate and eye,and ear defects