Development of Head and Neck Flashcards
Neural crest cells contribute which bones?
Bones of the face
they also contribute many more things
A baby is born with a midline cleft. Anything else to be worried about?
Intellectual disabilities. Median clefts are associated with loss of other midline structures, including those in the brain. Severe form is Holoprosencephaly.
Patient has a midline bump on the anterior neck. What could it be?
Thyroglossal cyst.
-results from incomplete regression of thyroglossal duct that follows the migration of the thyroid gland from the foramen cecum to neck.
Important signaling centers for head/neck development
- Rhombencephalic organizing center
- prosencephalic organizing center
Precursors for making head/neck structures (5)
- ectodermal placodes
- pharyngeal arches
- pharyngeal grooves
- pharyngeal pouches
- frontonasal prominence
olfactory placodes
- paired
- associated with telencephalon
frontonasal prominence
- olfactory node sits on this
- condensed mesenchyme
oropharyngeal membrane
- separates GI tract from outside (amniotic cavity)
- degenerates in normal devo
Origin of pharyngeal arch mesenchyme
- paraxial mesoderm (somites)
2. neural crest cells
Basic components of a pharyngeal arch, and what they become
- core of condensed mesenchyme (becomes cartilage)
- loose mesenchyme (fascia)
- head mesoderm (skeletal muscle)
- pharyngeal arch artery (aortic arch)
Pharyngeal arches:
-bones?
- Bones on front of skull, Incus, Malleus, Meckel’s cartilage, sphenomandibular ligament
- Stapes, superior horns of hyoid, styloid process, stylohyoid ligament
- Lower hyoid
- Laryngeal cartilages
- Laryngeal cartilages
Pharyngeal arches:
-cranial nerves?
- V2, V3
- VII
- IX
- X, superior laryngeal branch
- X, recurrent laryngeal branch
Pharyngeal arches:
-arteries?
- parts of maxillary a. and external carotid
- stapeidal a., but disappears
- common, internal carotids
4,6. aorta, subclavian, pulmonary arteries, ductus arteriosus
Pharyngeal grooves:
-Fate of each
- Middle ear canal
2,3,4. Cervical plexus, which degenerates
Pharyngeal grooves:
-Developmental problems?
- Fistulas, cysts
- Fistulas/cysts of arches 2,3,4 found anterior to SCM muscle
Pharyngeal arches:
-muscles?
- Mastication muscles, mylohyoid, ant.digastric, tensor palatini, tensor tympani
- Facial muscles of expression, Stylohyoid, post.digastric, stapedius
- Stylopharyngeus, leavator veli palatini
- Pharyngeal constrictors, cricothyroid
- intrinsic laryngeal muscles
DiGeorge syndrome:
head/neck devo problems?
-total or partial agenesis of 3rd and 4th pharyngeal pouch derivatives
Pharyngeal pouch derivatives
- Middle ear canal
- palatine tonsils
- inferior parathyroid glands, thymus
- superior parathyroid glands
What structures fuse to form the nasolacrimal duct?
Maxillar prominence fuses with Lateral nasal prominence and merges with Frontonasal prominence
Process of nasal cavity formation
- nasal sac forms from face surface
- oronasal membrane degenerates, connecting nasal and oral cavities
- secondary palate forms, separating both cavities
Choanal Atresia
- absence of L, R, or both nasal choanae, from failure of oronasal membrane to degenerate
- Bilateral choanal atresia dangerous because newborns are nasal breathers
2 parts of the palate
Primary and secondary palates.
Primary is found anteriorly and very small
L and R secondary palates fuse at midline
Critical weeks for facial development
Weeks 3-9
Arch 1 syndromes (3)
- Treacher Collins syndrome
- Pierre Robin sequence
- Crouzon syndrome
CHARGE syndrome
know Choanae Atresia
- colaboma (hole in eye)
- heart defects
- Atresia of Choanae
- retardation
- genital hypoplasia
- Ear anomalies
Tongue development:
- Body (ant. 2/3): Lateral and Medial Lingual swellings (arch 1, CN V)
- Root: Hypopharyngeal swelling (arch 3, CN IX)
- Muscle: occipital somite myotomes (CN XII)
Ankyloglossia
-Thickened frenulum under the tongue
