Head and Neck Embryology Flashcards
what forms the neural tube?
some of the ectoderm in the midline folds
what does the neural tube form?
brain and spinal cord
what are somites derived from?
paraxial mesoderm
what structures do somites form?
axial skeleton and muscles
help in cranial skeleton development
how many somites develop
33
what are brachial arches?
Series of arches which develop around the future mouth (stomatodeum) and pharynx.
what develops from the brachial arches?
face and neck
how many brachial arches develop?
In humans 5 branchial arches develop. (6 arches start to develop but arch number 5 disappears so we are left with arches 1,2,3,4 and 6. )
What embryological tissues make up the Branchial Arches?
Ectoderm lines the outside
Mesoderm in the middle
(+Neural crest cells)
Endoderm on the inside
which nerve forms from the 1st brachial arch?
X mandibular branch of trigeminal
which nerve forms from the 2nd brachial arch?
VII facial nerve
which nerve forms from the 3rd brachial arch?
IX glossopharyngeal nerve
which nerve forms from the 4th brachial arch?
X Superior laryngeal branch of vagus
which nerve forms from the 6th brachial arch?
X Recurrent laryngeal branch of vagus
name the 5 processes/prominences the face develops from
One frontonasal process
Two maxillary processes
Two mandibular processes
what forms the nostril?
Ectodermal thickening (nasal placode) pushes inwards or invaginates to form the nasal pit
what forms the philtrum?
The medial nasal process further grows downwards and laterally
give the 1st stage in the development of the palate?
Medial nasal process grows downwards and forms philtrum. This forms the primary palate
give the 2nd stage in the development of the palate?
From the maxillary processes, two palatine shelves grow inwards
give the 3rd stage in the development of the palate?
The palatine shelves meet in the midline to form the secondary palate.
if the palate doesn’t fuse properly what occurs?
Cleft lip and palate
what forms the flat bones of the cranium?
Membranous bones, formed by membranous ossification calvaria
what forms the irregular bones at base of skull?
Bones formed by endochondral ossification
what forms the skeleton of face
Partly from branchial arches, and partly from sensory (special sense) capsules
what can occur if the fontanelles fuse too early?
Craniosynostosis
what is the 1st pharyngeal arch abnormality called?
Treacher Collins syndrome
1st arch forms mandible + some of the ear bones (born deaf)
