Development Of Orofacial Structures Flashcards
Neurocranium
Derived from mesenchyme
-cartilaginous and membranous components
Bones of skull that house brain
-frontal, parietal, temporal, and occipital
Viscerocranium
Derived from mesenchyme
-cartilaginous and membranous components
Facial bones
-maxillary, Mandibular, nasal, lacrimal, etc
Neurocranium-Cartilaginous Parts
Occipital bone,
body of sphenoid bone,
ethmoid, and petrous and mastoid parts of temporal
Neurocranium-Membranous parts
Frontal and parietal bones
Viscerocranium-Cartillagenous
NCCs give rise to bones and connective tissues
Viscerocranium-Membranous
Maxillary prominence
Squamous part of temporal bone
Maxila
Zygomatic bone
What bones come from PA1
Malleus (connected to tympanic membrane) and Incus
What bones arise from PA2?
Stapes, Styloid process of temporal, and lesser horn
What bones arise from PA3?
Greater Cornu of hyoid b
What bones arise from PA4?
-GOTCHA!
Just laryngeal cartilage
What is Scaphocelpaly?
Immature closure of Sagittal suture
-causes wedge shaped head
—long and narrow
What is brachycephaly?
Immature closure of whole coronal suture
-tall head; tower like
Plagiocephaly-Cause?
Half of coronal suture
-twisted shaped head, one side sticks out
Trigionocephaly-Cause?
Frontal suture
-rounded point on forehead
5 facial primordial
- 2 maxillary prominences
- 2 Mandibular prominences
- 1 frontal
When do the facial primordial appear?
Appear during week 4
-around the stomodeum
What separates stomodeum from primordial pharynx?
The oropharyngeal membrane
-ruptures around day 26
What are the first parts of the face to form?
Oropharyngeal membrane ruptures, and then the mandibular prominences come together
When the don’t.. BUTT CHIN
-or called a chin dimple
Maxillary Prominences
Give rise to upper lip, maxilla, and secondary palate
-grow medially
Frontonasal prominence
Surrounds ventrolateral part of brain
-forehead and nose
Nasal Placodes
Bilateral oval thickenings of surface ectoderm
-gives rise to medial and lateral nasal prominences
What do medial and lateral nasal prominences form?
Nasal pits.. which then form primordial nares
What does the median nasal prominence form?
Grows toward midline w growth of maxillary prominences
-forms philtrum
Lateral nasal prominence formation
Separated from maxillary prominence by nasolacrimal groove
-merges w it by week 6
Nasal Cavity formation
Nasal placodes depress and form nasal pits
-mesenchyme from medial and lateral nasal prominences induce pits to become deeper=sacs
Sacs grow dorsal and ventral until they rupture at end of week 6 to form oral nasal cavity
Primordial Choanae
Connection between nasopharynx and nasal cavity
In Parkinson’s disease, what is the first thing to go?
Sense of smell as much as 10 years before
Weeks of palatogenesis
Weeks 6-12, with critical weeks 6-9
Primary Palate Formation
Primary
-fusion of medial nasal prominence forms medial palatine process
-premaxillary part separated by incessive fossa
Secondary Palate Formation
Develops from Lateral Palatine Process
-Mesenchymal projections extending from internal aspects of maxillary prominences
Final Palate Formation
Bone extends from maxillae and palatine bones into lateral palatine process to form hard palate
-posterior does not ossify
Nasal Septum
Downward growth of internal parts of merged medial nasal prominences
-fuses with lateral palatine processes
Cleft Lip and Palate-Most Common
Unilateral cleft lip on left is most common
-Risk factors include genetic and environment
—SHH, TGF-a
Choanal Atresia
Abnormalities of pterygoid plates and midfacial growth abnormalities
What does choanal atresia present as?
Airway obstruction, noisy breathing, or cyanosis that worsens during breathing but improves with crying
Tongue Development-Anterior 2/3
Median swelling ingulfed by lateral swelling
-PA1 mesenchyme
CN VII taste, IX sensation
Pharyngeal Part of Tongue
Hypopharyngeal eminences (arch 4) overgrows copula (arch 2)
Anterior 2/3 of tongue innervation
Sensation
-V3-lingual
Taste
-CN VII-Facial
Motor
-CN XII
Posterior 1/3 of tongue Innervation
Mucosa/Taste
-CN IX
Muscles
-CN XII
Sensation to Pharynx
-CN X
Palatoglossus M
-CN X
Glossoschissis
Split tongue
Ankyloglossia
Short lingual frenulum
-problem when breast feeding and speaking
Macroglossia
Enlarged tongue seen in Downs Syndrome
Odontogenesis
Induced from NCC and Oral Epithelium
-Dental Lamina lays down first, then tooth buds form from this
—made of ectoderm
Tooth Bud Contents
Enamel organ
-enamel epithelium and inner enamel epithelium
Dental Papilla
-dentin and pulp
Dentil Follicle
-mesenchym surrounding dental papilla and enamel organ
—cementum
Where do odontoblasts come from?
From dental papilla, next to inner enamel epithelium
Where do ameloblasts come from and what do they do?
From inner enamel epithelium differentiating
-produce enamel
Epithelial Root Sheeth
Fusion of inner and outer enamel epithelium
-root dentin produced by odontoblasts
Pulp
Central dental papilla
Cementum
inner cells of dental sac from cementoblasts
Periodontal ligament
Outer cells of dental sac
Eruption of teeth
Deciduous root of teeth reabsorbed by osteoclasts, deciduous teeth fall out and adult teeth arise
