Exam 3

Question 1

Which pharyngeal arch does not form/rapidly disintegrates?

Answer 1

PA 5

Question 2

What is a pharyngeal arch?

Answer 2

Paired transient structure located on ventral surface of embryo, core of mesenchyme, forms asynchronously

Question 3

What are pharyngeal clefts/grooves?

Answer 3

Series of invaginations lined by ectoderm forming on ventral (external) surface of pharyngeal arches

Question 4

What are pharyngeal pouches?

Answer 4

Invaginations that separate the pharyngeal arches on the dorsal (internal) surface

Question 5

What are the components of a pharyngeal arch?

Answer 5

Aortic arch (artery), cartilaginous rod, muscular components, cranial n.

Question 6

The first cleft and pouch are in what direction relative to Arch I?

Answer 6

Posterior

Question 7

Which arch has no cleft/pouch associated with it?

Answer 7

Arch VI

Question 8

What phenomenon creates the cervical sinus?

Answer 8

First and 2nd arch growing faster than 3rd and 4th arch which results in them being pushed towards midline and creating cervical sinus.

Question 9

Maxillary and mandibular prominence are part of which arch?

Answer 9

Arch I

Question 10

What does the first pouch form?

Answer 10

Eustachian tube, tympanic cavity

Question 11

What does the second pouch form?

Answer 11

Palatine tonsil

Question 12

What does the third pouch form?

Answer 12

Inferior parathyroid, thymus

Question 13

What does the fourth-sixth pouch form?

Answer 13

Superior parathyroid, ultimobranchial body

Question 14

Why do pharyngeal (cervical) cysts form?

Answer 14

Second arch failed to grow over arch 3 and 4, left remnant of cervical sinus.

Question 15

What is an external branchial fistula?

Answer 15

If remnant of cervical sinus forms a channel to the exterior or pharynx.
[Internal if sinus is connected to the pharynx (due to rupture of membrane between 2nd cleft and 2nd pouch)]

Question 16

What innervates pharyngeal arch I[mandibular arch]?

Answer 16

CN V - Trigeminal n. - maxillary and mandibular division

Question 17

What innervates arch II? (Hyoid arch)

Answer 17

CN VII - Facial n.

Question 18

What innervates arch III?

Answer 18

CN IX - Glossopharyngeal

Question 19

What innervates arches IV-VI?

Answer 19

Vagus n. CN X, superior laryngeal, recurrent laryngeal

Question 20

Where does meckel’s cartilage form from and what does it do?

Answer 20

Formed from arch I, supports first arch, malleus, incus.

Question 21

Malleus, Incus, Meckel’s cartilage are from which arch?

Answer 21

I

Question 22

Stapes, styloid process, stylohyoid ligament, lesser horn of hyoid bone are derived from what arch?

Answer 22

II

Question 23

Greater horn of hyoid & body of hyoid bone are derived from what arch?

Answer 23

III

Question 24

Thyroid cartilage is derived from what arch?

Answer 24

IV

Question 25

Cricoid cartilage is derived from what arch?

Answer 25

VI

Question 26

Which chromosome is responsible for mandibulofacial dystosis? (Treacher-collins syndrome)

Answer 26

Chromosome 5

Question 27

What protein is responsible for mandibulofacial dystosis (treacher-collins syndrome)?

Answer 27

Abnormal expression of Treacle protein in neural crest cells

Question 28

What arches are affected by treacher collins (mandibulofacial dystosis)?

Answer 28

Arches I & II [all structures]

Question 29

What are the characteristics of mandibulofacial dystosis? (Treacher-collins syndrome)

Answer 29

Downward slanting eyes, small lower jaw, malformed/missing ears. Anomalies can result in hearing, breathing and eating problems.

Question 30

What chromosome is responsible for DiGeorge Syndrome (DGS)?

Answer 30

Deletion of chromosome 22 (22q11.2)

Question 31

What arches/pouches are affected by DiGeorge Syndrome?

Answer 31

Arches/pouches III and IV, some involvement of I and II

Question 32

2 alternative names for DiGeorge Syndrome?

Answer 32

22q11.2, velocardiofacial syndrome

Question 33

Classic triad for DiGeorge syndrome?

Answer 33

Contruncal (outflow tracts) abnormalities, hypoplastic thymus and hypocalcemia

Question 34

What does Catch-22 stand for?

Answer 34

DiGeorge syndrome mnemonic Cardiac abnormality (PTA, tetralogy of Fallot, ASD, VSD) Abnormal faces (facial expressions typical, small mouth, smooth philtrum, micrognathia) Thymic aplasia (mild to severe) Cleft palate Hypoparathyroidism/Hypocalcemia

Question 35

What arches are responsible for Hemifacial microsomia - Goldenhar (Oculo-Auriculo-Vertebral) Syndrome?

Answer 35

Congenital 1st and 2nd arch defect usually affecting one side of body

Question 36

Symptoms of hemifacial microsomia (Goldenhar) syndrome?

Answer 36

Maxillary, temporal and zygomatic bones are small/flat, small mandible, anotia/microtia, benign eye tumors, scoliosis/kyphosis, abnormal rib structure, tetralogy of Fallot & VSDs

Question 37

What does the 1st pharyngeal cleft form?

Answer 37

External auditory meatus

Question 38

What do clefts 2,3 and 4 form?

Answer 38

Fuse to form cervical sinus which eventually degenerates.

Question 39

What is a pharyngeocutaneous fistula?

Answer 39

Persistent cervical sinus forming a fistula connecting skin and pharynx.

Question 40

Ear drums form from what?

Answer 40

Cleft mesenchyme in between first pouch

Question 41

What gives rise to C-Cells (thyroid)?

Answer 41

Ultimobranchial body

Question 42

Where does the thyroid migrate from/to?

Answer 42

Migrates from base of tongue to inferior to laryngeal prominence

Question 43

Where does the parathyroid migrate from/to?

Answer 43

Migrates from posterior surface of thyroid; inferior pair (3rd pouch) originates superior to superior pair (4th pouch)

Question 44

Thyroglossal duct degenerates to form what?

Answer 44

Foramen cecum

Question 45

What is the migration of the ultimobranchial body?

Answer 45

4th pouch to incorporation into thyroid gland; forms parafollicular (C) cells

Question 46

Where does the thymus migrate from?

Answer 46

3rd pouch to anterior mediastinum

Question 47

What are the derivatives of pharngeal pouch I?

Answer 47

Tympanic cavity (middle ear), auditory tube

Question 48

What are the derivatives of pharyngeal pouch 2?

Answer 48

Palatine tonsils (Tonsilar fossa)

Question 49

What are the derivatives of pharyngeal pouch 3?

Answer 49

Inferior pair of parathyroid glands, thymus

Question 50

What are the derivatives of pharyngeal pouch 4?

Answer 50

Superior pair of parathyroid glands, parafollicular (C) cells of thyroid gland

Question 51

The tympanic membrane forms where?

Answer 51

At boundary of cleft and pouch I, thus formed from ectoderm, endoderm and the intervening mesenchyme

Question 52

What is the diagnostic feature for the thymus?

Answer 52

Hassall's corpuscles

Question 53

What is ectopic thymus tissue?

Answer 53

Mass in mandibular angle usually, need to do a needle biopsy, misdiagnosed as tumor or cyst.

Question 54

Colloid/thyroglobulin are broken down/activated into what and by what?

Answer 54

T3/T4 via TSH

Question 55

What is a thyroglossal cyst?

Answer 55

Occurs as thymus migrates, can be anywhere in midline along migratory path of thyroid gland.

Question 56

Where does the anterior 2/3 of the tongue receive its sensory innervation from?

Answer 56

CN V, nerve to first arch

Question 57

Where does posterior 1/3 of tongue receive its sensory innervation from?

Answer 57

CN IX, nerve to 3rd arch

Question 58

What is ankyloglossia?

Answer 58

Tongue-tie, short frenulum of tongue anchor tongue to floor

Question 59

What is bifid tongue?

Answer 59

Lateral lingual swellings fail to fuse

Question 60

What is macroglossia?

Answer 60

Hypertrophy of the tongue, chromosomal amyloid disorders, hypothyroid disorders, acromegaly

Question 61

The tongue develops from what arches?

Answer 61

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