Embryology Flashcards
What does the frontal nasal prominence develop into?
The forehead, eyelids, dorsum of nose, philtrum
What are the areas of the face before they’re developed?
Frontal nasal prominence
Maxillary prominence x2
Mandibular prominence x2
Stomatodeum
What do the maxillary prominences develop into?
The cheeks
Lateral nose
Most of the lip
Upper jaw
What do the mandibular prominences develop into?
The chin
Lower jaw
Lower mouth
How does the nose develop?
Nasal pits invaginate
Ectoderm grows around them to form nasal placodes which are divisible into lateral and medial on each side
They then move to the centre with the development of the face and medial prominences fuse and the maxillary prominences also fuse with medial prominence
How does the philtrum form?
Due to the fusion of the medial prominences
What seperates the oral and nasal cavities during development before the two have fused?
The oronasal membrane
How do the palates form?
From the palatal shelves of the maxillary prominence and the primary palate formed by the medial nasal prominence
The mandible grows and allows the tongue to drop and the shelves can then fuse
The nasal septum then fuses with the palatal shelf
What is cleft palate?
When there is a failure of fusion
What is cleft lip?
When the median nasal prominences fail to fuse
How do the eyes develop?
Out pockets of the forebrain emerge and are covered with ectoderm
On the lateral head
Form optic placodes which then come into position with the development of the face
Eyelids develop at end of embryonic period and then reopen in third trimester
How do the ears develop?
They are otic placodes on the neck and rise with development
Incus and malleus form from the 1st pharyngeal arch
Stapes develop from the 2nd pharyngeal arch
External auditory meatus develops from the 1st pharyngeal cleft
What is foetal alcohol syndrome?
This is when there is a small face, thin philtrum, small eyes and small nasal opening due to alcohol
Cannot tell extent of alcohol that harms but it is also very harmful to the brain
How many pharyngeal arches are there?
6 but the 5th is rudimentary
What are the pharyngeal arches separated by on the outside?
Clefts
What are the pharyngeal arches separated by on the inside?
Pouches
What does each arch contain?
Artery, nerve, vein, mesenchyme
What does the mesenchyme of each arch develop into
Mesoderm as muscle
Neural crest as cartilage
What are the nerves of the pharyngeal arches?
1 - trigeminal
2 - facial
3 - glossopharyngeal
4+6 vagus - superior laryngeal and recurrent laryngeal
What are the muscles of the first arch?
Tensor tympani Masstication Anterior Digastric Mylohyoid Tensor palatini
What are the muscles of the 2nd arch
Stapedius Facial expression Posterior Digastric Ears Stylohyoid
What is the muscle of the 3rd arch?
The stylopharyngeus
What are the muscles of the 4th arch?
Cricothyroid
Levator palatini
Larynx
Pharynx
What are the regions of the brain?
Pro cephalon
Mesocephalon
Rhombocephalon
What arches give rise to blood vessels in the adult?
3rd - ICA
4th - aorta and brachiocephalic
6th - pulmonary arch
What is the first cartilage bar called?
Meckels cartilage
What forms from Meckels cartilage?
Maxillary
Mandibule
Maleus and incus
What is the second cartilage bar called?
Reichters cartilage
What forms from the reichters cartilage?
Stapes
Superior hyoid
Lesser cornil of hyoid
What forms from the 3rd cartilage bar?
Upper cornil of hyoid
Lower hyoid
What forms from the 4th cartilage bar?
Hypo branchial eminence which later becomes the epiglottis
What forms from the 4th and 6th cartilage bars?
The thyroid cartilage
Cricoid cartilage
Arteryoid cartilage
What forms from the 1st pharyngeal cleft?
External auditory meatus
What forms from 2-6th cartilage clefts?
Cervical sinus as the 2nd grows down
Cervical sinus obliterated
What forms from the 1st pharyngeal pouch?
Eustachian tube and inner ear
What forms from the 2nd pharyngeal pouch?
Crypts of palatine tonsil
What forms from the 3rd pharyngeal pouch?
Inferior parathyroid from dorsal
Thymus from the ventral
What forms from the 4th pharyngeal pouch?
Dorsal - superior parathyroid
Ventral - thyroid c cells
