Aortic Arches, Branchial Clefts, Arches And Pouches

Question 1

First Aortic arch derivatives:

Branch of?

Answer 1

Maxillary artery- branch of the external carotid

Question 2

Second aortic arch derivative

Answer 2

Stapedial artery and hyoid artery

Question 3

Third aortic arch derivative

Answer 3

Common carotid and proximal part of internal carotid artery

Question 4

Fourth aortic arch

Answer 4

Right- proximal R. subclavian artery

Left- aortic arch

Question 5

Sixth aortic arch derivative

Answer 5

Left= Proximal pulmonary arteries

Ductus arteriosus

Question 6

Branches arches make up structures composed of:

1st Branchial arch

Answer 6

Mesoderm and neural crest cells

Cartilage- Maxillary process, mandibular process, malleus and incus, sphenomandibular ligament
Muscles- muscles of mastication (temporalis, masseter, lateral and medial pterygoids), mylohyoid, anterior belly of digastric, tensor tympani, anterior 2/3 of tongue, tensor veli palatini
Nerve- CN V3

Question 7

Second branchial arch

Answer 7

Stapes, styloid process, lesser horn of the hyoid*, stylohyoid ligament
Muscles of facial expression, stapedius, stylohyoid, platysma, posterior belly of digastric
Nerve- CN VII

Question 8

third branchial arch

Answer 8

Greater horn of the hyoid*
Stylopharyngeus muscle *
CN IX ^^

Question 9

4th-6th branchial arches

Answer 9

Arytenoids, cricoid, corniculate, cuneiform, thyroid**
4th- most pharyngeal constrictors; cricothyroid, levator veli palatini
6th- all intrinsic muscles of larynx except for cricothyroid

4th- CN X, superior laryngeal branch
6th- CN X, recurrent laryngeal/inferior laryngeal branch

Question 10

Which arches form the posterior 1/3 of the tongue?

Anterior 2/3?

Answer 10

Branchial arches 3 and 4

Branchial arch 1

Question 11

First Branchial pouch

Answer 11

Middle ear cavity, Eustachian tube, mastoid air cells (endoderm lined structures of ear)

Question 12

second branchial pouch

Answer 12

Epithelial lining of palatine tonsil

Question 13

3rd branchial pouch

Answer 13

Inferior parathyroid- dorsal

Thmus- ventral

Question 14

4th branchial pouch

Answer 14

Superior parathyroids- dorsal

Parafollicular cells of thyroid (neural crest derived) invades ultimobranchial body- ventral

Question 15

Branchial pouches consist of
Branchial clefts (grooves) consist of

Answer 15

Endoderm!

Ectoderm!

Question 16

first branchial cleft

2nd-4th clefts- pathology?

Answer 16

External auditory meatus

Temporary cervical sinuses, obliterated by fusion/proliferation of second arch mesenchyme. Persistence= cleft cyst anterior to the SCM muscle on lateral neck, freely mobile, cutaneous free opening

Question 17

The CFTR transmembrane protein is an ______ type of channel

Answer 17

ATP-gated - 2 ATPs causes pore to open

CF receptors can have mutated ATP binding, blocking chloride ion secretion.

Question 18

Autoclave machines for surgical sterilization- lower temperatures limited to 100C would allow for what bacteria to remain on the surgical equipment?

Answer 18

Spore producing- most commonly clostridium perfringens and botulinum and Bacillus anthracis

Question 19

Rate control drugs vs rhythm control drugs

What antiarrhythmics can lead to QT interval prolongation, which predisposes to TdP

Answer 19

Rate- beta and calcium channel blockers
Rhythm- attempts to maintain sinus rhythm with antiarrhythmics like sotalol, amiodarone and flecainide

Class III- amiodarone, sotalol, ibutilide, dofetilide: predominantly block potassium channels and inhibit outward repol during phase 3. But **sotalol and ibutilide have greatest risk of TdP

Question 20

UTI pathogen plated on eosin methylene blue agar that produces a distinct green metallic sheen and also beta hemolysis on blood agar

Answer 20

E. Coli* (lactose fermenting bacteria bind to dye in the agar and produce purple or black colonies, E. Coli produces a green sheen on EMB)