Aortic arches, Branchial apparatus derivatives

Question 1

What does the 1st aortic arch give rise to?

Answer 1

Part of MAXillary artery (branch of ECA).

1st arch is MAXimal.

Question 2

What does the Second aortic arch give rise to?

Answer 2

Stapedial and hyoid artery.

Second = Stapedial

Question 3

What does the 3rd aortic arch give rise to?

Answer 3

Common Carotid and proximal part of internalCarotid.

C is 3rd letter of alphabet.

Question 4

What does the 4th aortic arch give rise to?

Answer 4

Left: Aortic Arch
Right: Proximal part of right subclavian artery
(4th arch, 4 limbs –> systemic)

Question 5

What does the 6th aortic arch give rise to?

Answer 5

Proximal part of pulmonary arteries

Left: ductus arteriosus.

Question 6

Where does the right recurrent laryngeal nerve loop around?

Answer 6

Right subclavian artery

Question 7

Where does the left recurrent laryngeal nerve get caught?

Answer 7

Crosses under the arch of the aorta at the point of the ductus arteriosus

Question 8

What are the subdivisions of the branchial apparatus/pharyngeal apparatus?

Answer 8

Clefts/grooves - ectoderm
Arches - Mesoderm (muscles, arteries + neural crest (bones, cartilage)
Pouches - derived from endoderm

Question 9

What is the topographic organization of the branchial apparatus?

Answer 9

CAP covers outside to inside.
Clefts are ectoderm - outermost layer
Arches are mesoderm - meaty middle layer.
Pouches are endoderm - Inner indentations

Question 10

Where is the branchial/pharyngeal apparatus located?

Answer 10

Between primitive pharynx and primitive esophagus. 1st-4th = highest to lowest.

Question 11

How many branchial clefts are there?

Answer 11

4.

Question 12

What does the 1st branchial cleft become?

Answer 12

external auditory meatus.

Question 13

What do the 2nd-4th branchial clefts form?

Answer 13

Temporary cervical sinuses, obliterated by 2nd arch mesenchyme.

Question 14

What happens if a branchial cleft failures to obliterate and leaves a cervical sinus?

Answer 14

Branchial cleft cyst within LATERAL neck.

Question 15

What cartilaginous structures arise from the 1st branchial arch?

Answer 15

Meckel cartilage:

Mandible, Malleus (+incus), and spheno-Mandibular ligament

Question 16

What muscles arise from the 1st branchial arch?

Answer 16

Muscles of Mastication.
(temporalis, Masseter, lateral and medial pterygoids), Mylohyoid, anterior belly of digastric, tensor tympani, tensor veli palatini.

Question 17

What nerves arise from 1st branchial arch?

Answer 17

CN V2 and V3 (chew)

Question 18

What is treacher collin’s syndrome?

Answer 18

1st arch neural crest failures to migrate –> mandibular hypoplasia, facial abnormalities.

Question 19

What cartilaginous structures arise from the 2nd branchial arch?

Answer 19

Reichert cartilage: 
Stapes, Styloid 
process, lesser horn 
of hyoid, Stylohyoid 
ligament.

Question 20

What muscles arise from the 2nd branchial arch?

Answer 20

Muscles of facial expression,
Stapedius, Stylohyoid,
platySma, posterior belly
of digastric

Question 21

What nerves arise from 2nd branchial arch?

Answer 21

CN VII (facial expression - smile!)

Question 22

What is congenital pharygocutaneous fistula?

Answer 22

Persistence of cleft and pouch - fistula between tonsillar area and lateral neck.

Question 23

What cartilaginous structures arise from the 3rd branchial arch?

Answer 23

Greater horn of the hyoid

Question 24

What muscles arise from the 3rd branchial arch?

Answer 24

Stylopharyngeus (think
of styloPHARYNGEOUS
innervated by
glossoPHARYNGEAL nerve)

Question 25

What nerves arise from 3rdbranchial arch?

Answer 25

``` CN IX (styloPHARYNGEOUS). "Swallow stylishly" ```

Question 26

What cartilaginous structures arise from the 4th-6th branchial arches?

Answer 26

Cartilages: thyroid, cricoid, arytenoids, corniculate, cuneiform

Question 27

What muscles arise from 4th-6th branchial arches?

Answer 27

4th arch: most pharyngeal constrictors; cricothyroid, levator veli palatini 6th arch: all intrinsic muscles of larynx except cricothyroid

Question 28

What nerves arise from 4th - 6th branchial arch?

Answer 28

``` 4th arch: CN X (superior laryngeal branch) "simply swallow" 6th arch: CN X (recurrent laryngeal branch) "speak" ```

Question 29

What do branchial arches 3 and 4 form?

Answer 29

Posterior 1/3 of tongue

Question 30

What does arch 5 make?

Answer 30

No major developmental contributions

Question 31

Mnemonic for arch nerves?

Answer 31

``` at Mcdonalds (golden arches), kids chew (V2, V3) smile (CN VII) swallow stylishly (IX) simply swallow (Xsuperior laryngeal) then speak (X recurrent larygn). ```

Question 32

What are the derivatives of the 1st branchial pouch?

Answer 32

Develops into middle ear cavity, eustachian tube, mastoid air cells.

Question 33

What are the derivatives of the 2nd branchial pouch?

Answer 33

Develops into epithelial lining of palatine tonsil

Question 34

What are the derivatives of the 3rd branchial pouch?

Answer 34

Dorsal: Inferior parathyroids Ventral: Thymus

Question 35

What are the derivatives of the 4th branchial pouch?

Answer 35

Superior parathyroids

Question 36

What's weird about the 3rd and 4th branchial pouches?

Answer 36

3rd pouch structures end up below 4th pouch structures.

Question 37

What is DiGeorge syndrome?

Answer 37

Aberrant development of 3rd and 4th pouches --> T cell deficiency (thymic aplasia) and hypocalcemia (failure of parathyroids). Associated with truncal cardiac abnormalities.

Question 38

What is MEN2A?

Answer 38

Mutation of germline RET - neural crest cells. - Parathyroid tumor (3rd/4th pharyngeal pouch) - Parafollicular cells - medullary thyroid, derived from 4th/5th pharyngeal pouches. - Pheochromocytoma

Question 39

What is cleft lip caused by?

Answer 39

Failure of fusion of the maxillary and medial nasal processes (formation of primary palate).

Question 40

What is cleft palate caused by?

Answer 40

Failure of fusion of the two lateral palatine processes or failure of fusion of lateral palatine processes w/ the nasal septum or median palatine process - formation of 2ndry palate.