Last. Embro Lecure Flashcards
The cranium develops from _______ around the developing brain
mesenchyme
_____: a bony case that encloses the brain • _____: bones comprising the facial skeleton
neurocranium viscerocranium
formation of Cartilaginous neurocranium:
Several cartilages fuse, forming the base of cranium via endochondral ossification) Occipital bone (base) is made first → body of sphenoid → ethmoid bone →Temporal bone (petrous and. mastoid parts)
formation of membranous neurocranium
Mesenchyme at the sides & top of the brain form calvaria (frontal & parietal bones) via intramembraneous ossification • Interconnected via sutures
Cartilaginous Viscerocranium makes what
our PA derivates.
NCC makes: bones, CT and craniofascial structures
PA1: malleus & incus •
PA2: stapes, styloid process of temporal bone; lesser horn of the hyoid • PA3: greater horns of the hyoid bone. •
PA4: cartilages fuse → laryngeal cartilages (except epiglottis)
Membranous Viscerocranium: makes what
Maxillary prominence,
squamous temporal,
maxilla,
zygomatic bone via intramembranous ossification
what is craniosynostosis?
premature fusion of cranial structures, often assc with other defects. we don’t know why shit happens but it happens more to Boyz Scapthocephaly brachycephaly plagiocephaly trigonocephaly
Scaphocephaly
premature closure of sagittal suture → cranium becomes long, narrow, & wedge shaped
Brachycephaly
premature closure of the coronal suture → a high, tower-like cranium
Plagiocephaly
premature closure of the coronal suture on one side → cranium is twisted & asymmetric
Trigonocephaly
premature closure of the frontal (metopic) suture causes deformities in frontal and orbital bones
FaceDevelopment How do we form face?
1. Around week 4: five facial primordia appear around studoenum: 2 maxillary (lateral), 2 mandibular (caudal) and 1 frontonasal prominence_, separated by oropharyngeal membrane_ (separating them from the primordial oropharynx
- Mandibular prominence fuse and extend -> causing oropharyngeal membrane to disintegrate at day. 26 -> stuodeum -> creating opening to oral cavity and l_ower lip and lower jaw._
- Nasal placodes (surface ectoderm) form on inferolateral frontonasal prominence, which make the medial and lateral nasal prominences.
- MNP and LMP leave nasal placodes -> nasal pits, which form the n_ostrils and nasal cavities._
- Maxillary prominences grow medially forcing medial nasal prominence towards midline
- Nasolacrimal groove separates LNP and MXP.
- Be end of week 6-> fuse
- Week 7- 10: Medial nasal prominences (MNP) fuse with maxillary prominence and LNP -> make intermaxillary segment, which makes philtrum of upper lip and primary palate.
Frontonasal prominence (FNP) surrounds the ventrolateral part of forebrain and does what?
Frontal portion-> will form the forehead Nasal portion -> forms rostral boundary of stomodeum & nose
NCC forms: forebrain & midbrain
PA1 splits to form maxillary & mandibular prominences
Maxillary prominences (MXP) form lateral boundaries of stomodeum (midbrain & hindbrain NCC) • Mandibular prominences (MDP) form caudal boundary of stomodeum (midbrain & hindbrain NCC)
NCC from both will make midbrain and hindbrain
what is the first of the face o form
lower jaw and lower lip.
how does our nasal cavity develop?
- As our face is developing, nasal placodes depress and become nasal pits.
- MNP/LNP get bigger. and cause the pits to get deeper, making our primordial nasal sacs -> grow into forebrain, separated. from the oral cavity. by oronasal membrane
- at the end of week 6, the oronasal membrane ruptures and connects nasal and oral cavities, creating our PRIMORDIAL CHOANE (opening from nasal cavity. -> nasal pharynx).
- After secondary palate develops, related to the junction of the nasal cavity. and pharynx.
epithelium in the roof of the nasal cavity becomes what
olfactory epithelium
when does palate develop
week 6-12
what is the critical period for palate development
9, when the tongue is being developed.
describe development of palate
- Primary palate is made by the fusion of medial nasal prominences (MNP)-> forms the median palatine process (primary plate)
- Secondary palate is made by fusion of lateral palatine processes: Bone develops in the primary palate. , making the premaxillary part of maxilla. Bone extends into the maxilla -> extends to the into lateral palatine process -> hard palate
- Posteiro prortions do not ossify. and extend and fuse to form soft. palate and uvula, seen at the. palatine rape.
4. Nasal septum fuses with palatine process (week 9)
Cleft Palate occurs when
when the primordial do not fuse properly. can be unilateral or bilateral
Lateral palatine process do not fuses with nasal septum or with the medial palatine process.
cleft lip
cleft extends through upper lids maxillary. prominence do note fuse currently with MNP (medial nasal prominence)
how does nasal septum form
merged medial nasal prominences grow down.
Nasal septim and palatine process fuses at week 9 and is completed by week 12.
Median lingual swelling appears week_____
4
• Tongue muscles are derived from _______
occipital myotomes
how. to form tongue
- Lateral lingual swellings fuse at midline, overgrow to. form anterior. 2/3. of tongue
- posterior 1/3 arises from hypopharyngeal eminence, which overgrows PA2 -> make posterior 1/3. of tongue
Glossoschissis
bifed tongue d/t lateral lingual swellings not fusing
ankyglossia
connection between tongue and floor is too long
