Week 1 - K - Embryology 2 - Face, Palate and nasal cavities Flashcards
What embryological structures give rise to the musculature of the face and neck?
The core of mesenchyme derived from the mesoderm
What embryological structures give rise to the skeletal components of the face?
The neural crest cells of the pharyngeal arches
What is the nerve supply to each of the pharyngeal arches?
Arch 1 - ventral portion - mandibular division of trigeminal nerve dorsal portion - maxillary division of trigeminal nerve Arch 2 - facial nerve Arch 3 - glossopharyngeal nerve Arch 4 - superior laryngeal branch of vagus nerve Arch 6 - recurrent laryngeal branch of vagus nerve
What is the musculature from arch 1?
Musculature - muscles of mastication, anterior belly f digastric, tensor veli palatini and tensor tympani muscle
What is the skeletal components from arch 1? (maxillary and mandibular processes)
Skeletal components - Maxillary potion - maxilla, zygomatic process and temporal bone Mandibular - Meckel’s cartilage - maandible, incus and malleus
What muscles of the face does pharyngeal arch 2 give rise 2? Name 2 other muscles it gives rise to?
Gives rise to the muscles of facial expression Also gives rise to the stapedius muscle and the stylohyoid muscle (also posterior part of digastric muscle)
The pharyngeal arches develop in week 4and and 5 of embryology What are the exact days of embryology in which they develop?
Arch 1 - 22 days Arch 2&3 - 25 days Arch 4&5 - 29days
What are the 5 facial swellings present from week 4 of development?
Frontonasal prominence Maxillary prominence (x2) Mandibular prominence (x2)
The frrontonasal prominence contains nasal placodes, what do the nasal placodes give rise to?
The nasal placodes give rise to the olfactory epithelium of the nose
What pharyngeal arch gives rise to the maxillary and mandibular prominence? (each prominence is supplied by their own nerve)
Pharyngeal arch 1 - has a maxillary and mandibular prominence
The frontonasal, maxillary and mandibular prominences all surround a central opening What is this central opening called and what does it give rise to?
The central opening is known as the stomodeum Gives rise to the future mouth
What are the nasal swellings that develop on the frontonasal prominence in week 5?
The medial nasal prominences (x2) and The lateral nasal prominences (x2)
What is a big driving force for the development of the nasal swellings?
One of the big driving forces for development is the development of the maxilla. They put pressure on the nasal swellings and gradually move them in towards the midline.
What Lies between the Maxillary prominence and the Lateral Nasal Prominence ?
The nasolacrimal groove
The epithelium lining the nasolacrimal groove will form a solid epithelial cord Once the cord detaches from the ectoderm, what happens?
It undergoes canalisation (formation of a canal) to form the nasolacrimal duct
Where does the nasolacrimal duct drain into? Explain the process of formation of the nasolcarimal duct from groove to duct?
Nasolacrimal duct drains into the inferior concha The nasolacrimal groove is situated between the maxillary prominence and the lateral nasal prominence. The epithelium lining the groove solidifies to form an epithelial cord which detaches from the ectoderm and undergoes canalisation. This forms the nasolacrimal duct
Which components of the face form the upper lip?
2 medial nasal prominences and 2 maxillary processes
What does the mandibular prominence form?
Forms the lower lip and jaw
Which part of the nose does the frontonasal prominence form?
Forms the bridge and nasal septum
What forms the crest, tip and ala (alae = plural) of the nose? That is a picture of the baby at 10 weeks
Crest and tip are formed by the medial nasal prominences and the ala is formed by the lateral nasal prominences
Run through again What do the different prominences form?
Lip Upper lip - formed by 2 maxillary prominences and 2 medial nasal prominences Lower lip - formed by the mandibular prominence Nose Bridge and septum - frontonasal prominence Crest and tip - medial nasal prominence Alae (ala = single) - laterl nasal prominences
What prominence does the development of the primary palate (small portion of hard palate behind the incisors) begin with?
Begins with the fusion of the median nasal prominences
What does the fusion of the medial nasal prominences give?
The fusion of the medial nasal prominences gives the intermaxillary segment
The intermaxillary segment has a Labial portion Upper jaw component Palatal component What do each of these go on to form?
The labial portion forms the philtrum of upper lip Upper jaw component carries 4 incisors Palatal component forms the primary palate
What does the philtrum of the upper lip connect?
Connects the upper lip to the septum of the nose
At week six of embryo development, what grows downwards from the maxillary prominence?
The palatine processes (shelfs) of the maxillary bone - they originally go on either side of the tongue as they tongue begins its development supeirorly and then goes downwards allowing the palatine shelfs to fuse
What do the palatine processes fuse together to form?
They fuse together to form the secondary hard palate (posterior part of hard palate)
What is formed at the apex of fusion between the primary palate (formed by the medial nasal prominences giving rise to the intermaxillary segement) and the secondary palate? (formed by the maxillary prominences growing palatine shelfs (prominences) which fuse)
The incisive foramen is formed Basically at 10 weeks, the palate, nasal cavity and most of face structure is formed
What does the blue part represent? What causes an isolated cleft palate? more common in males or females? Cleft means partially divided into two
The blue section represents the intermaxillary segment Isolated cleft lip is due to a clefting of the palatine shelves however the intermaxillary segment works normally More common in females (Intramaxillary segment works normally but the shelves havent fused)
Is cleft lip more common in females or males?
More common in males caused by the failure of fusion of the primary plate
What causes D and E?
D is caused by failure of fusion of the palatine shelves - isolated cleft palate E is caused by a defect in the nasolacrrimal duct causing a facial cleft
The nasal placode becomes the nasal pit before becoming the olfactory epithelium lining the roof of the nasal cavity At week 6, Nasal pits deepen and penetrate into the underlying mesenchyme What separates the nasal pits from the oral cavity? (when does the separating membrane breakdown_
Separated from the oral cavity by the oronasal membrane which breaksdown late week 6
