Pharyngeal Arches Flashcards
most congenital anomalies in head and neck originate during transformation of the pharyngeal apparatus into its adult derivatives
pharyngeal arches
pharyngeal arches develop in the _____ (#) week as ____________ that migrate into the future head and neck regions
4th week, neural crest cells
Appear as surface elevations to the developing pharynx
primordium of the jaws (the first pair of pharyngeal arches)
by the end of the 4th week, how many well-defined pairs of pharyngeal arches are visible externally
four
rudimentary and not visible on the surface of the embryo
5th and 6th arches
arches are separated from each other by prominent fissures called
pharyngeal grooves (clefts)
the first pharyngeal arch (mandibular arch) develops into two prominences:
maxillary and mandibular prominences
gives rise to the maxilla, zygomatic bone, ad squamous part of the temporal bone
maxillary prominence of the first pharyngeal arch
forms the mandible
mandibular prominence of the 1st pharyngeal arch
makes a major contribution to the formation of the hyoid bone
second pharyngeal arch (hyoid arch)
appears as a slight depression of the surface ectoderm, its separated by the oropharyngeal membrane
stomodeum (primordial mouth)
the stomodeum is separated from the cavity of the primordial pharynx by a bilaminar membrane
oropharyngeal membrane
ruptures at 26 days, bringing the primordial pharynx and foregut into communication with the external environment
oropharyngeal membrane
Initially, each pharyngeal arch consists of a core of ________ and is covered externally by _______ and internally by ________
mesenchyme (embryonic CT), ectoderm, endoderm
the original mesenchyme is derived from mesoderm in what week
third week
during the 4th week, most of the mesenchyme is derived from __________ that migrate into the pharyngeal arches
neural crest cells
a typical pharyngeal arch contains:
aortic arch, cartilaginous rod, muscular component, and a nerve
an artery that arise from the truncus arteriosus of the primordial heart
aortic arch
forms the skeleton of the arch
cartilaginous rod
forms muscles in the head and neck
muscular component of pharyngeal arches
supplies the mucosa and muscles derived from the arch
nerve of pharyngeal arches
nerve deriving from the first arch (mandibular)
mandibular nerve/ V3 of trigeminal nerve (CN V)
muscles of the first arch (mandibular)
muscles of mastication, myohyoid and ant. belly of digastric, tensor tympani, and tensor veli palatini
skeletal structure of first arch
malleus and incus
ligaments deriving from the first arch (mandibular)
anterior ligament of malleus and sphenomandibular ligament
nerve deriving from the second arch (hyoid)
fascial nerve (CN VII)
muscles deriving from the second arch (hyoid)
muscles of fascial expressions, stapedius m., stylohyoid m., post. belly of digastric
skeletal structures deriving from the second arch (hyoid)
stapes, styloid process, lesser horn and upper part of body of hyoid bone
ligaments deriving from second arch (hyoid)
stylohyoid ligament
nerve deriving from the 3rd arch
glossopharyngeal (CN IX)
muscles deriving from the 3rd arch
stylopharyngeus
skeletal structure from 3rd arch
greater horn and lower part of body of hyoid bone
nerve deriving from 4th arch
superior laryngeal branch of VAGUS (CN X)
muscles deriving from 4th arch
cricothyroid and levator veli palatini
skeletal structures deriving from 4th arch
thyroid cartilage and cricoid cartilage
nerve deriving from 6th arch
recurrent laryngeal branch of VAGUSs (CN X)
muscles of the 6th arch
constrictors of pharynx, intrinsic muscles of larynx, striated muscles of esophagus
skeletal structures derived from the 6th arch
arytenoid cartilage, corniculate cartilage, and cuneiform cartilage
during the 5th week, the 2nd pharyngeal arch enlarges and overgrows the 3rd and 4th arches, forming an ectodermal depression called
the cervical sinus
