|
Major features to identify
for each: arch, pouch, groove
and membrane.
Contribute to the
formation of head and neck and in the human appear
at the 4th week.
The first arch
contributes the majority of upper and lower jaw
structures.
Structures
derived from Arches
|
ARCH
|
Nerve
|
Muscles
|
Skeletal
Structures
|
Ligaments
|
|
1 (maxillary/mandibular)
|
trigeminal (V)
|
|
malleus, incus
|
ant lig of malleus, sphenomandibular
ligament
|
|
2
(hyoid)
|
facial (VII)
|
|
stapes, styloid process, lesser cornu
of hyoid, upper part of body of hyoid
bone
|
stylohyoid ligament
|
|
3
|
glossopharyngeal (IX)
|
|
greater cornu of hyoid, lower part of
body of hyoid bone
|
|
|
4 & 6
|
superior laryngeal and recurrent
laryngeal branch of vagus (X)
|
|
thyroid, cricoid, arytenoid,
corniculate and cuneform cartilages
|
|
Structures
derived from Pouches
Each pouch is lined with
endoderm and generates specific
structures.
|
POUCH
|
Overall
Structure
|
Specific
Structures
|
|
1
|
tubotympanic recess
|
tympanic membrane, tympanic cavity,
mastoid antrum, auditory tube
|
|
2
|
intratonsillar cleft
|
crypts of palatine tonsil, lymphatic
nodules of palatine tonsil
|
|
3
|
inferior parathyroid gland, thymus
gland
|
|
|
4
|
superior parathyroid gland,
ultimobranchial body
|
|
|
5
|
becomes part of 4th pouch
|
|
Structures
derived from Grooves
Only the first
groove differentiates into an adult
structure and forms part of the external acoustic
meatus.
Structures
derived from Membranes
At the bottom of each
groove lies the membrane which is formed from the
contact region of ectodermal groove and endodermal
pouch. Only the first membrane
differentiates into an adult structure and forms
the tympanic membrane.
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