embryology I Flashcards
What are the 3 components of the pharyngeal apparatus
pharyngeal clefts, pharyngeal arches, and pouches
what is the derivative of the 4 pharyngeal clefts
ectoderm
what do the pharygeal arches arise from
core of mesenchyme (neural crest and paraxial mesoderm)
what does the neural crest of pharyngeal arches give rise to
CT
what does the paraxial mesoderm of pharygeal arches give rise to
muscles
how many pharyngeal arches are there and describe inn and blood supply
6, each has own CN and an aortic arch artery
the 5th regresses leaving 1-4 and 6
what do the pharyngeal pouches arise from
pharyngeal endoderm, 4 pouches
What are the skeletal derivatives of the 1st pharyngeal arch
viscerocranium (melleus, incus) and CT of face
what are the muscular derivatives of the 1st pharyngeal arch
muscles of mastication: temporal is, masseter, medial and lateral pterygoids
anterior belly of digastric, mylohyoid, tensor tympani, tenosr veli palatini
What nn inn 1st pharyngeal arch
trigeminal, mandibular V3
what membrane forms between the processes of the first pharyngeal arch
oropharyngeal membrane
outer layer of ectoderm and inner layer of endoderm
Know that the nerves of the arches are the only CN that have SVE component
V3, facial, vagus, glossopharyngeal
When does the oropharyngeal membrane rupture and allows communication between what 2 structures
day 26, communication between pharynx and oral cavity
What are the skeletal derivatives of the 2nd pharyngeal arch
stapes, styloid process of temporal bone
stylohyoid lig, lesser horn and superior portion of hyoid
what are the muscular derivatives of the 2nd pharyngeal arch
muscles of facial expression
also stylohyoid, posterior belly of digastric, stapedius
what n inn the 2nd pharyngeal arch
facial CN VII
what are the skeletal derivatives of the 3rd pharyngeal arch
greater horn and infeiror portion of body of hyoid bone
what are the muscular derivatives of the 3rd pharyngeal arch
stylopharyngeus
what n inn the 3rd pharyngeal arch
CN IX glossopharyngeal
what are the skeletal derivatives of the 4th pharyngeal arch
all laryngeal cartilages (with 6th arch)
what are the muscular derivatives of the 4th pharyngeal arch
muscles of pharynx(except stylopharyngeus) and cricothyroid
what n inn the 4th pharyngeal arch
Vagus CN X
what are the skeletal derivatives of the 6th pharyngeal arch
all laryngeal cartilages with arch 4
what are the muscle derivatives of the 6th pharyngeal arch
laryngeal mm(not cricothyroid) and skel m of the esophagus
what n inn the 6th pharyngeal arch
Vagus X - recurrent laryngeal n
What does the 1st pharyngeal pouch become
formation of middle ear and auditory tube
what does the 2nd pharyngeal pouch become
stroma of palatine tonsil, tonsillar fossa
what does the 3rd pharyngeal pouch become
dorsal- inferior parathyroid glands
ventral- thymus
What does the 4th pharyngeal pouch become
dorsal- superior parathyroid gland
ventral- ultimobranchial body
What does the first pharyngeal cleft become
external ear- TM and external auditory meatus
what happens to the pharyngeal clefts 2-4
the second arch overgrows and buries the clefts and so they become the cervical sinus that gets obliterated
What is the thyroid gland derived from
median endodermal thickening of pharyngeal floor
how does the thyroid gland stay connected to the tongue as it descends
thyroglossal duct- degenerates week 7
which opening of the thyroglossal duct remains open
superior called foramen cecum
what is a pyramidal lobe of thryoid gland
remnant of distal thyroglossal duct
the parafollicular C cells in thyroid gland are derived form what
ultimobranchial body of 4th pouch
what forms the body(ant 2/3) of the tongue
1st pharyngeal arch so receives GSA trigeminal
somati because coming from ectoderm
What forms the roof or posterior 1/3 of tongue
3rd arch so GVA from CN IX, glossopharyngeal
what forms the epiglottic region of tongue
4th arch so GVA from CN X vagus
the muscle of the tongue is derived from what
paraxial mesoderm of occipital somites
what causes ectopic thyroid and parathyroid tissue
remnants along course of migration
What causes lateral cervical cysts or branchial cysts
when the cervical sinus fails to degenerate, found along anterior border SCM
What causes branchial fistulas
external and internal
when second arch fails to overgrow 3rd and 4th arches, cervical sinus will retain connection with surface causing and external fistula
internal is caused when lateral cervical cysts opens into pharynx
Where are thyroglossal cysts found and why
near midline of the neck because remnant of thyroglossal duct
What are examples of neural crest migration defects in the face
treacher collins syndrome, robins sequence, DiGeorge Anomaly
What are the components of DiGeorge Syndrome
deletion long arm chromosome 22 CATCH 22 cardiac anomalies chrom 22 abnormal facies thymic hypoplasia parathyroid dysfunction
What is a main sign of parathyroid dysfunction
hypocalcemia
Neural crest disorders always present with what type defects
craniofacial
