Aortic arches, Branchial apparatus derivatives Flashcards
What does the 1st aortic arch give rise to?
Part of MAXillary artery (branch of ECA).
1st arch is MAXimal.
What does the Second aortic arch give rise to?
Stapedial and hyoid artery.
Second = Stapedial
What does the 3rd aortic arch give rise to?
Common Carotid and proximal part of internalCarotid.
C is 3rd letter of alphabet.
What does the 4th aortic arch give rise to?
Left: Aortic Arch
Right: Proximal part of right subclavian artery
(4th arch, 4 limbs –> systemic)
What does the 6th aortic arch give rise to?
Proximal part of pulmonary arteries
Left: ductus arteriosus.
Where does the right recurrent laryngeal nerve loop around?
Right subclavian artery
Where does the left recurrent laryngeal nerve get caught?
Crosses under the arch of the aorta at the point of the ductus arteriosus
What are the subdivisions of the branchial apparatus/pharyngeal apparatus?
Clefts/grooves - ectoderm
Arches - Mesoderm (muscles, arteries + neural crest (bones, cartilage)
Pouches - derived from endoderm
What is the topographic organization of the branchial apparatus?
CAP covers outside to inside.
Clefts are ectoderm - outermost layer
Arches are mesoderm - meaty middle layer.
Pouches are endoderm - Inner indentations
Where is the branchial/pharyngeal apparatus located?
Between primitive pharynx and primitive esophagus. 1st-4th = highest to lowest.
How many branchial clefts are there?
4.
What does the 1st branchial cleft become?
external auditory meatus.
What do the 2nd-4th branchial clefts form?
Temporary cervical sinuses, obliterated by 2nd arch mesenchyme.
What happens if a branchial cleft failures to obliterate and leaves a cervical sinus?
Branchial cleft cyst within LATERAL neck.
What cartilaginous structures arise from the 1st branchial arch?
Meckel cartilage:
Mandible, Malleus (+incus), and spheno-Mandibular ligament
What muscles arise from the 1st branchial arch?
Muscles of Mastication.
(temporalis, Masseter, lateral and medial pterygoids), Mylohyoid, anterior belly of digastric, tensor tympani, tensor veli palatini.
What nerves arise from 1st branchial arch?
CN V2 and V3 (chew)
What is treacher collin’s syndrome?
1st arch neural crest failures to migrate –> mandibular hypoplasia, facial abnormalities.
What cartilaginous structures arise from the 2nd branchial arch?
Reichert cartilage: Stapes, Styloid process, lesser horn of hyoid, Stylohyoid ligament.
What muscles arise from the 2nd branchial arch?
Muscles of facial expression,
Stapedius, Stylohyoid,
platySma, posterior belly
of digastric
What nerves arise from 2nd branchial arch?
CN VII (facial expression - smile!)
What is congenital pharygocutaneous fistula?
Persistence of cleft and pouch - fistula between tonsillar area and lateral neck.
What cartilaginous structures arise from the 3rd branchial arch?
Greater horn of the hyoid
What muscles arise from the 3rd branchial arch?
Stylopharyngeus (think
of styloPHARYNGEOUS
innervated by
glossoPHARYNGEAL nerve)
What nerves arise from 3rdbranchial arch?
CN IX (styloPHARYNGEOUS). "Swallow stylishly"
What cartilaginous structures arise from the 4th-6th branchial arches?
Cartilages: thyroid,
cricoid, arytenoids,
corniculate, cuneiform
What muscles arise from 4th-6th branchial arches?
4th arch: most pharyngeal
constrictors; cricothyroid,
levator veli palatini
6th arch: all intrinsic
muscles of larynx except
cricothyroid
What nerves arise from 4th - 6th branchial arch?
4th arch: CN X (superior laryngeal branch) "simply swallow" 6th arch: CN X (recurrent laryngeal branch) "speak"
What do branchial arches 3 and 4 form?
Posterior 1/3 of tongue
What does arch 5 make?
No major developmental contributions
Mnemonic for arch nerves?
at Mcdonalds (golden arches), kids chew (V2, V3) smile (CN VII) swallow stylishly (IX) simply swallow (Xsuperior laryngeal) then speak (X recurrent larygn).
What are the derivatives of the 1st branchial pouch?
Develops into middle ear
cavity, eustachian tube,
mastoid air cells.
What are the derivatives of the 2nd branchial pouch?
Develops into epithelial lining of palatine tonsil
What are the derivatives of the 3rd branchial pouch?
Dorsal: Inferior parathyroids
Ventral: Thymus
What are the derivatives of the 4th branchial pouch?
Superior parathyroids
What’s weird about the 3rd and 4th branchial pouches?
3rd pouch structures end up below 4th pouch structures.
What is DiGeorge syndrome?
Aberrant development of 3rd and 4th pouches –> T cell deficiency (thymic aplasia) and hypocalcemia (failure of parathyroids). Associated with truncal cardiac abnormalities.
What is MEN2A?
Mutation of germline RET - neural crest cells.
- Parathyroid tumor (3rd/4th pharyngeal pouch)
- Parafollicular cells - medullary thyroid, derived from 4th/5th pharyngeal pouches.
- Pheochromocytoma
What is cleft lip caused by?
Failure of fusion of the maxillary and medial nasal processes (formation of primary palate).
What is cleft palate caused by?
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.
