pharyngeal arches

Question 1

pharyngeal arch 1 CN

Answer 1

CN V

Question 2

pharyngeal arch 2 CN

Answer 2

CN VII

Question 3

pharyngeal arch 3 CN

Answer 3

CN IX

Question 4

pharyngeal arch 4 CN

Answer 4

CN X

Question 5

pharyngeal arch 1 aortic arch, gives rise to?

Answer 5

Aortic arch I: becomes maxillary aa

Question 6

pharyngeal arch 2 aortic arch, gives rise to?

Answer 6

aortic arch 2; gives rise to hyoid and stapedial aa which normally go away with development

Question 7

pharyngeal arch 3 aortic arch, gives rise to?

Answer 7

aortic arch 3; common cartoid and proximal internal carotid aa

Question 8

pharyngeal arch 4 aortic arch, gives rise to?

Answer 8

aortic arch 4; right subclavian and the aorta

Question 9

mm dereived from pharyngeal arch 1

Answer 9

masticory
tensor tympani 
mylohyoid 
tensor palatini veli 
anterior digastric

Question 10

mm dereived from pharyngeal arch 2

Answer 10

facial expression mm
stylohyoid 
platysma 
post digastric 
stapedius

Question 11

mm dereived from pharyngeal arch 3

Answer 11

stylopharyngeus

Question 12

mm dereived from pharyngeal arch 4

Answer 12

pahrygeal and laryngeal mm

Question 13

skeletal derivatives of arch 1

Answer 13

malleus 
incus 
sphenoman ligament 
meckel's cartilage-mandible 
tympanic ring

Question 14

skeletal derivatives of arch 2

Answer 14

stapes
styloid
lesser horn of hyoid
stylohyoid ligament

Question 15

skeletal derivatives of arch 3

Answer 15

greater horn

body of hyoid

Question 16

skeletal derivatives of arch 4

Answer 16

laryngeal cartilages

Question 17

pharyngeal groove/cleft vs pouch

Answer 17

groove/cleft: outside of where two arches meet

pouch: inside of where two arches meet

Question 18

first pharyngeal groove (where arches 1 and 2 meet) becomes?

Answer 18

external ear/ external auditory meatus

Question 19

2nd, 3rd, 4th pharyngeal grooves become?

Answer 19

cervical sinuses: temporary, pathology if not resorbed

Question 20

1st pharyngeal pouch becomes (where arches 1 and 2 meet)?

Answer 20

middle ear and eutaschian tube

Question 21

2nd pharyngeal pouch becomes (where arches 2 and 3 meet)?

Answer 21

supratonsilar fossa

Question 22

3rd pharyngeal pouch becomes (where arches 3 and 4 meet)?

Answer 22

thymus and inf PTG

Question 23

4th pharyngeal pouch becomes (where arches 4 and 5 meet)?

Answer 23

sup PTG

post brachial body

Question 24

when does the pharyngeal region form

Answer 24

around the 4th week

Question 25

pharyngeal complexes

Answer 25

Blocks of mesenchymal tissue separated externally by pharyngeal clefs (grooves) and internally by pharyngeal pouches. The pharyngeal complexes are crucial for normal formation of the neck & face.

Question 26

components of pharyngeal arches

Answer 26

``` Pharyngeal arch (skeletal, muscular, nerve & artery components)  Pharyngeal clefts (external)  Pharyngeal pouches (internal) ```

Question 27

processes and names of the first arch

Answer 27

the first (mandibular) arch has two processes - the maxillary and the mandibular (really 3 if you include the frontonasal).

Question 28

which arches form face/neck? can be observed externally?

Answer 28

The first two pharyngeal arches develop into facial and neck structures that can be observed externally, the other arches do not.

Question 29

neural crest migration to the arches

Answer 29

 Neural-crest migrates into the arches  The migrating neural crest cells differentiate into the skeletal element of each arch,  Branches of specific cranial nerves, which are derived from neuroectoderm, migrate into each pharyngeal arch.

Question 30

Development of the Arterial System

Answer 30

 6 pair of aortic arches, one for each arch  Connect aortic sac/TA to dorsal aortae heart developing ventricle and atria

Question 31

structures found in each pharyngeal arch

Answer 31

 Skeletal element  Muscles  A branch of a specific cranial nerve  Artery

Question 32

skeletal elements of arch 1

Answer 32

 The migrating neural crest in the first arch induce the formation of a cartilaginous rod (Meckel’s cartilage).  The more posterior portion differentiates and becomes ossified into the malleus and the incus.  The more anterior portion of Meckel's cartilage serves as a scaffolding for intramembranous bone formation of the mandible. In between the two middle ear bones and the mandible, the sphenomandibular ligament forms, connecting the first arch skeletal elements.  In addition, the maxilla, zygoma and part of the temporal bone form in the maxillary portion of the first arch.

Question 33

skeletal elements of arch 2

Answer 33

 The skeletal elements of the second arch initially appear as a bar of cartilage (Reichert’s).  The posterior portion differentiates into the stapes & the styloid process of the temporal bone.  The anterior portion differentiates into the lesser horns (cornu) and the superior portion of the hyoid bone. In between these elements, the stylohyoid ligament is formed.

Question 34

Skeletal elements – | Arches 3,4 & 6

Answer 34

The skeletal elements of the third pharyngeal arch are the greater horns (cornu) and inferior portion of the hyoid bone. Skeletal elements of the fourth-sixth pharyngeal arches differentiate into all the laryngeal cartilages (thyroid, arytenoid, corniculate, cuneiform, and cricoid), except the epiglottis (comes from the laryngeotracheal diverticulum)

Question 35

general rule for what mm come from each arch?

Answer 35

mm inn by nerve of that arch 1: CNV 2: CNVII 3: CNIX 4: CNX

Question 36

Terminal branches of maxillary artery are associated with?

Answer 36

the first pharyngeal arch.

Question 37

 Tissues of the second pharyngeal arch are supplied by? (aa)

Answer 37

the stapedial artery, which regresses.

Question 38

 The common carotid artery and root of internal carotid artery are associated with?

Answer 38

with the third pharyngeal arch.

Question 39

The ductus arteriosus and roots of pulmonary arteries are associated with which arches?

Answer 39

the fourth-sixth pharyngeal arches.

Question 40

treacher-collins

Answer 40

 Mandibulo-facial dysostosis |  Underdevelopment of structures associated with Arch 1.

Question 41

Pierre Robin Sequence

Answer 41

Micro-/Retrognathia=glossoptosis (pushes tongue back) to cause airway obstruction

Question 42

pharyngeal clefts become?

Answer 42

The first pharyngeal cleft deepens and forms the external auditory meatus and canal. This is the only cleft that gives rise to an adult structure. The second-fourth clefts become overgrown by the second pharyngeal arch and, thus, become enclosed as a cervical sinus. Normally, this cervical sinus regresses.

Question 43

ectopic thyroid

Answer 43

thyroid develops at the foramen cecum and will migrate to its adult position may have misplaced thyroid tissues along this route or still present on the tongue=lingual thyroid

Question 44

formation of the eustachian tube

Answer 44

The first pouch increases in size and migrates towards the first pharyngeal cleft. As the pouch and cleft approach each other, the auditory (pharyngotympanic or eustachian) tube is formed and the endoderm of the first pouch forms the lining of the middle ear (tympanic cavity).

Question 45

tympanic membrane formation

Answer 45

At its most distal end, endoderm of the first pouch becomes approximate to the ectoderm of the first pharyngeal cleft with only a small amount of mesoderm separating them. This is the site of the tympanic membrane.

Question 46

second pharyngeal pouch becomes? what forms beneath it?

Answer 46

site of the tonsillar fossa in the adult Underneath the endoderm of the second pouch develops pit-like depressions (tonsillar crypts) mesoderm differentiates into lymphoid tissue that is called the palatine tonsils.

Question 47

Pharyngeal Pouch 3 develops?

Answer 47

Dorsally, the posterior endodermal region develops into bilateral inferior parathyroid glands (III), which migrate toward the posterior aspect of the inferior pole of the thyroid gland. Ventrally, the anterior endodermal region of the third pouch differentiates bilaterally into thymus gland tissue. Each part migrates inferiorly and fuses with its counterpart in the midline, and the united gland migrates inferiorly to the superior mediastinum of the thorax.

Question 48

how can the inferior PTG form more superior than the superior PTG?

Answer 48

inf will migrate further down and eventually be inf to the sup PTG

Question 49

Pharyngeal Pouches 4-5 develop?

Answer 49

The posterior endoderm develops into superior parathyroid glands that migrate to the posterior aspect of the thyroid gland. The anterior endoderm of the fourth pouch develops an ultimobranchial body that migrates to the thyroid gland. Cells from the ultimobranchial body differentiate into parafollicular cells (C cells) that produce calcitonin. The endoderm of the fifth pharyngeal pouch contributes to the formation of the ultimobranchial body

Question 50

Digeorge syndrome

Answer 50

failure of the thymus gland to develop from the third pharyngeal pouch

Question 51

adult derivatives of pharyngeal pouch 1

Answer 51

Auditory (pharyngotympanic, eustachian) tube, middle ear (tympanic cavity), part of the eardrum (tympanic membrane)

Question 52

adult derivatives of pharyngeal pouch 2

Answer 52

Tonsillar crypts

Question 53

adult derivatives of pharyngeal pouch 3

Answer 53

Inferior parathyroid glands | Thymus gland

Question 54

adult derivatives of pharyngeal pouch 4

Answer 54

Superior parathyroid glands | Ultimobranchial body

Question 55

adult derivatives of pharyngeal pouch 5

Answer 55

Ultimobranchial body

Question 56

anterior 2/3 of the tongue development

Answer 56

Median tongue bud; overgrown by lateral lingual swellings, fusion indicated by the median sulcus

Question 57

posterior third of the tongue development

Answer 57

Mesoderm of the second pharyngeal arch forms a central process (copula) It is overgrown by a central process from the third and fourth pharyngeal arches, the hypopharyngeal (hypobranchial) eminence, which develops into the posterior one-third of the tongue.

Question 58

between the anterior and posterior tongue?

Answer 58

terminal sulcus

Question 59

mm of the tongue development and inn

Answer 59

Muscles of the tongue develop from the mesoderm of the occipital myotomes that migrate into the developing tongue. Branches of the hypoglossal nerve (CN XII) follow the migrating occipital myoblasts and thus innervate the intrinsic muscles of the tongue

Question 60

formation of the thyroid gland

Answer 60

The endodermal mass of cells invaginates into the underlying mesoderm, creating the thyroid diverticulum that is positioned between the anterior two-thirds and posterior one-third of the developing tongue. The thyroid diverticulum grows inferiorly, often between the skeletal elements of the second and third pharyngeal arches. It then migrates to a position anterior to the upper portion of the developing trachea. connection between origin of thyroid diverticulum and the thyroid gland is called the thyroglossal duct and normally regresses over time, if not thyroglossal duct cyst