Flashcards in LEC48: The Branchial Arches Deck (67):
model organism for understanding human head/neck structures
defn of branchial
of or relating to the gills or to parts of the body derived from the embryonic branchial arches and clefts
4 components of branchial apparatus
1) branchial arches (pharyngeal arches)
2) pharyngeal pouches
3) branchial grooves (pharyngeal clefts)
4) branchial membranes
when in embryogenesis do branchial arches appear?
how many swellings by day 28?
when does largest branchial arch appear?
when do ruptured membranes occur in branchial arch development?
which branchial arches aren't well understood?
how many branchial arches are there?
which branchial arches are very closely related?
6th & 4th
what migrates into branchial/pharyngeal arches?
neural crest cells
4 components of branchial arches
2) muscles derived from mesodermal mass of each arch
3) skeletal component- bone, cartilage, or precursor
4) artery (deriatives of aortic arch)
cranial nerve assoc w/ 1st branchial arch
CNV: trigeminal nerve (has 3 parts, V1, V2, V3)
cranial nerve assoc w/ 2nd branchial arch
CNVII: facial nerve
cranial nerve assoc w/ 3rd branchial arch
CNIX: glasopharyngeal nerve
cranial nerve assoc w/ 4th branchial arch
CNX: vagus nerve
cranial nerve assoc w/ 5th & 6th branchial arch
cranial root of spinal accessory n
(CN XI via Vagus)
where do head/neck muscles come from?
either from branchial arches or from structures that migrate into head/neck
where do muscles of head/neck originate from
myotomes, which're from somites
tongue muscles derived from?
ocular muscles derived from?
what surrounds area of developing inner ear?
meckel's cartilage & reichert's cartilage
where is meckel's cartilage derived from? what does it become?
from branchial arch I
precursor of mandible
malleus, incus, stapes
ear bones from 1st branchial arch?
upper pt of malleus, incus
ear bones from 2nd branchial arch?
bottom pt of malleus and incus; arch of stapes
muscles derived from 1st branchial arch
1) muscles of mastication: masseter, temporalis, lateral pterygoid, medial pterygoid
3) ant. belly of digastric
4) tensor veli palatini
5) tensor tympani
skeletal elements of 1st branchial arch
1) head of malleus
2) upper part of incus
3) meckel's cartilage - mandible precursor
artery components of 1st branchial arch
1) 1st pair of aortic arches
2) remaining pts of maxillary aa
3) may contribute to ext. carotid aa
first branchial arch is aka
second branchial arch is aka
muscle derivatives of 2nd branchial arch
1) facial expression
4) post. belly of digastric
skeletal elements of 2nd branchial arch
1) handle of malleus
2) lower part of incus
3) arcs of stapes
4) styloid process
5) lesser cornu, upper body of hyoid
why is CNVII path important?
if have lesions to facial nerve, get Bell's Palsy- effects muscles of facial expression, location matters
relationship between CNIX and CNX?
CNIX= glossopharyngeal n
shares forebrain stem nuclei w/ CNX, vagus n. - tied in fxn
nerve of gag reflex?
CNIX, glossopharyngeal n
muscle related to 3rd branchial arch?
skeletal elements of 3rd branchial arch
greater horn (cornu) of hyoid; lower part of body of hyoid
artery of 3rd branchial arch
1) 3rd pair of aortic arches
2) proximal pts: common carotid aa
3) distal pts: pts of int carotid aa
muscles related to 4th branchial arch?
cricothyroid - and others it shares its innervation w/:
levator veli palatini
skeletal components related to 4th branchial arch?
artery of 4th branchial arch?
1) 4th pair of aortic arches
2) left arch- pt of aortic arch
3) right arch- part of R subclavian a
which aortic arch is L subclavian a derived from?
NONE! it's not derived from an aortic arch
muscles of 5th & 6th branchial arches
1) all intrinsic muscles of larynx except cricothyroid
2) levator veli palatini
4) pharyngeal constrictors
skeletal components of 5th & 6th brancial arches
artery of 5th & 6th branchial arches
1) 5th or 6th pair of aortic arches
2) L & R proximal parts persist as proximal pumonary aa
L distal - ductus arteriosus
R distal - degenerates
what is ductus arteriosus derived form?
L distal 6th branchial arch
what are pharyngeal pouches derived from?
function of pharyngeal pouches in embryo?
line inside of developing embryo
derivative of 1st pharyngeal pouch?
inner workings of ear:
1) tubotympanic recess: prox part- auditory (pharyngotympanic) tube;
2) distal pt- middle ear cavity & mastoid antrum
derivatives of 2nd pharyngeal pouch?
not obliterated pt > crypts of palatine tonsil
derivatives of 3rd pharyngeal pouch?
ventral pt- primordia of THYMUS
dorsal pt- inf parathyroid glands
derivatives of 4th pharyngeal pouch?
ventral pt- ultimobranchial body (fuses w/ thyroid glands)
dorsal pt- sup parathyroid glands
maybe portions of lat thyroid gland
derivatives of 5th pharyngeal pouch?
usu considered pt of 4th ultimobranchial body
what persists from pharyngeal clefts/branchial grooves? which cleft's it from?
ONLY external acoustic meatus
from 1st pharyngeal cleft
what happens to 2nd-4th pharyngeal clefts?
temporarily exist as common cervical sinus; usu disappears; may become branchial sinus / branchial fistula
what are branchial membranes
pt of branchial apparatus
appear where epithelia of a branchial groove & pharyngeal pouch approach each other
what in adults persists from branchial membranes?
from 1st branchial membrane, only 1 pair: tympanic membrane
what might persist from pharyngeal clefts, in baby?
complete fistula aka branchial cyst
presents as oozing from side of neck
what's mandibular hypoplasia?
1st arch problem
failure of meckel's cartilage, failure of upper portions of malleus, incus to develop
what/when does 1st endocrine gland appear in embryo?
thyroid gland, day 24
where does thyroid gland descend from?
foramen cecum - point in the tongue
descent path of thyroid gland?
from foramen cecum in tongue > chisels through tongue > descends down anterior part of neck > anterior pt of neck finally
cause of malformation/variation in thyroid?
as descends down anterior pt of neck, things may be in its way
what might be in way of thyroid gland as descends?
1) pyramidal lobes/persistent thyroglossal ducts
2) thyroglossal duct cysts & sinuses
3) ectopic thyroid gland
where might get cyst in neck re: thyroid?