Embryology Flashcards
(28 cards)
what is mesenchyme?
embryonic connective tissue which develops into bone, cartilage, blood vessels etc
how many branchial arches are there?
5
begins as 6 but one disappears (5th one so you are left with 1,2,3,4 & 6)
name a condition that is caused by an abnormality of one of the branchial arches, which branch is affected, and the effect this has on the person.
treacher collins syndrome
1st phalangeal arch
abnormal development of structures supplied by the trigeminal nerve V3 - mandible, ears ect
what makes up the branchial / phalangeal arches?
endoderm (also forms clefts between arches)
mesoderm + neural crest cells (cartilage and muscle
ectoderm (also forms pouches between arches)
what are the nerves of the brachial arches?
1st = mandibular branch of trigeminal (CN V3) 2nd = facial (CN VII) 3rd = glossopharyngeal (CN IX) 4th = superior laryngeal (CN X) 6th = recurrent laryngeal (CN X)
if there is abnormal development of the 2nd branchial arch, name a few things that will be affected?
muscles of facial expression
posterior belly of digastric
anterior half of EAC
stapes of the middle ear
from what branch in the branchial arches/phalangeal arches does the ossicles develop from?
malleus and incus - 1st branch
stapes - 2nd branch
why is the nerve supply of the tongue so complex and what is the nerve supply?
complex because it is formed from 3 branchial rings
sensory - lingual and chord tympani branches of facial (VII) (anterior) & glossopharyngeal (IX) (posterior)
motor for both - hypoglossal (XII)
what does the face develop from?
5 processes;
one frontonasal processes
two maxillary processes
two mandibular processes
which process which forms the face fuses?
mandibular
what forms the palate?
medial nasal process forms Philtrum which forms primary palate
The palatine shelves grow from the maxillary process and meet inward
what forms the nostrils?
nasal placode from the frontonasal process
how are the cranial vault bones formed?
membranous ossification calabria
how are the bones of the base of the skull formed?
endochondral ossification
how is the viscerocranium developed?
partly from branchial arches and partly from sensory capules
after birth what is clinically significant in terms of the membranous ossification of the cranial vault?
doesn’t full form at birth
the 6 membrane covered fontanelle is of clinical significance as it is a ‘soft spot’
what is a contidion associated with abnormal development of the cranial vault?
craniosynostosis
fusion of the sutures too quickly
what does the layers of the retina develop from?
the optic cup
outer 10th layer from the outer layer of optic cup
inner 9 layers from the inner layer of the optic cup
why is the development of the retina of clinical significance?
because theoretical layers is formed from the inner and outer layers of the optic cup this creates a potential space between the 10th layer and the inner 9 layers.
retinal detachment can occur when fluid fills in this space separating the layers
what forms from the mesenchyme of the developing eye?
choroid
storm of cornea
sclera
extra ocular msucles
how does the lens become transparent in the developing eye?
the lens fibres form the epithelium of the lens vesicle
the epithelium then loses its nuclei to become transparent
what forms from the surface ectoderm of the developing eye?
eyelids
conjunctiva
corneal epithelium
where does the eye develop from?
the neural tube
its an extension of the brain
optic vesicles which form the eye grow outwards from which part of the neural tube?
diencephalon
