BIOL110 Lecture Notes - Cochlea, Hypoplasia, Pharyngeal Arch

36 views3 pages
30 Jan 2013
Department
Course
Outline of Lecture 06
Head and Neck Development
I. Initial events
A) Sources of tissue
- neural crest cells bones of face/skull, cartilage, connective tissue
- mesoderm occipital bone, laryngeal cartilage
- somitomeres voluntary muscles of head and neck
B) Principles of development
- 7 somitomeres form in head region from paraxial mesoderm
- Somitomeres induce segmental development of brain (e.g. rhombomeres)
- NCC’s migrate to arches, carrying HOX code with them (prevents
segment mixing)
II. Pharyngeal arches (aka branchial arches)
- Arch is made of mesoderm, lined by ectoderm (outside) and endoderm (inside)
- Clefts (outside) and pouches (inside) separate the arches
Arc
h
Artery Nerv
e
Skeleton Muscles Pouch Cleft
1Maxillary V Maxilla,
mandible
mm. of
mastication 1 Tympani
c cavity,
eustachia
n tube
Ext. aud.
meatus,
eardrum
2
Hyoid,
stapedial
VII Stapes,
styloid,
part of
hyoid
facial mm.,
post. digastric,
stylohyoid,
stapedius 2 Palatine
tonsil
Cervical
sinus
(degenerat
es)
3Carotid IX Part of
hyoid
Stylopharyngeu
s 3 Thymus,
inf.
parathy.
4
Right
subclavian
, aortic
arch
X
(sup.
laryn.
)Laryngea
l
cartilages
(4,6)
Cricothyroid,
lev. palatine,
pharynx
constrictors
4 Sup.
parathy.
5 - - 5 Ultimobr
anchial
body
6
Pulmonar
y
X
(recu
r.lary
n.)
Intrinsic larynx
mm.
III. Tongue
- Tongue is occipital mesodermal muscle (inn. by XII) covered with endodermal
mucosa
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