Development of Branchial Arches

Question 0

Branchial Pouch

Answer 0

Endodermal outpocketing from rostral foregut

Question 1

Branchial groove

Answer 1

Ectodermal cleft between banchial arches

Question 2

Branchia Membrane

Answer 2

Point of contact between branchial clefts and pouches

Question 3

Stomadeum

Answer 3

Forms oral and nasal cavity; composed of ectoderm

Question 4

Oropharyngeal membrane

Answer 4

Site of contact between stomadeum (ectoderm) and endoderm

-Pharynx begins here

Question 5

Palatoglossal Arch

Answer 5

Site of oropharyngeal membrane

Question 6

First Arch Strutures

Answer 6

CN (V)

Bones:

Malleus
Incus

Ligaments:

Anterior ligament of the malleus
Sphenomandibular Ligament

Muscles:

Muscles of Mastication
Tensor tympani
Tensor palati
Mylohyoid 
Anterior belly of digastric

Question 7

Second Arch Structures

Answer 7

CN (VII)

Bones:

Stapes
Styloid Process
Lesser Horn of hyoid bone (upper half)

Ligaments:

Stylohyoid ligament

Muscles:

Muscles of facial expression
Stapedius
Stylohyoid
Posterior belly of the digastric muscle

Question 8

Structures of the Third Arch

Answer 8

CN (IX)

Bones:

Greater Horn of the hyoid bone; lower half

Muscles:

Stylopharyngeus

Question 9

Structures of the Fourth Arch

Answer 9

CN (X)

Bones:

Structures of the larynx

Muscles:

Muscles of the larynx
Muscles of the pharynx (ex. stylopharyngeus)
Muscles of the palate (ex. tensor palati)

Question 10

Structures of the Sixth Arch

Answer 10

CN (XI)

Muscles:

Trapezius
Sternocleidomastoid

Question 11

Structures of the First cleft, membrane, and pouch

Answer 11

Cleft: External auditory meatus

Membrane: Tympanic membrane

Pouch: Auditory tube, Tympanic cavity

Question 12

Structures of the Second Pouch

Answer 12

Crypts of the palatine tonsils

Question 13

Structures of the third pouch

Answer 13

Inferior parathyroid gland

Thymus

Question 14

Structures of the Fourth Pouch

Answer 14

Superior Parathyroid gland

C-cells of thyroid gland

Question 15

Branchial Fistula

Answer 15

Channel connecting the pharynx to the skin of the neck; occurs due to malformation of first branchial pouch structures

Passes anterior to sternocleidomastoid and in between the internal and external carotid arteries

Question 16

Branchial Cyst

Answer 16

Forms due to a remnant of the cervical sinus

Question 17

Thyroid Development

Answer 17

1. Begins as thickening at foramen cecum on the floor of the pharynx
2. Elongates to form Thyroid diverticulum and descends anterior to hyoid and larynx
3. Thyroglossal duct connects diverticulum to Foramen cecum`

Question 18

Thyroglossal duct remnants

Answer 18

Can form cysts along descending path

Question 19

Treacher-Collins Syndrome

Answer 19

“First Arch Syndrome”

Neural crest cells do not migrate to Arch 1

-mandibular hypoplasia, conductive hearing loss, facial malformation

Question 20

Second Brancial Cleft Cyst

Answer 20

Most common

tract linked to palatine tonsils