Head And Neck Development I Flashcards
Overview: what do the following bony parts enclose/contain?
- Membrane bones enclose/replace?
- Chondrocranium enclose/form?
- Visceral skeleton forms?
- Enclose cranium and replace cartilage precursors in the jaw
- Enclose sensory organ capsules, forms base of brain case
- Form endochondral bones in the jaws and neck
Timeline:
- What develops during 4th week
- During weeks 5-7, enclosure of __ and migration of __
- 6th week is development of
- Branchial arch (aka pharyngeal arch)
- Branchial grooves and migration of thyroid glands
- Bony elements
Innervation of the following pharyngeal arches:
- First
- Second
- Third
- Fourth-sixth
- CN V (maxillary and mandibular)
- CN VII
- CN IX
- CN X
Why is there no arch 5?
It either doesn’t develop or it develops and then regresses
3 components of each pharyngeal arch
Cartilaginous, nerve and aortic arch
Pharyngeal arches are swellings of __ derived from __ and __
Mesenchyme; derived from lateral plate mesoderm and neural crest cells
- Location of pharyngeal grooves (clefts)
2. What are they derived from?
- Indentions between pharyngeal arches
2. Ectoderm
- Location of pharyngeal pouches
2. What are they derived from?
- Indentations between pharyngeal arches
2. Endoderm
What is a closing membrane
The place where pharyngeal groove meets pharyngeal pouch
How does growth of neck occur?
Through migration of neural crest cells (NOT from mesodermal proliferation)
What other 3 things form from neural crest migration?
Cartilaginous elements, tendons, and connective tissue of branchial muscles
- Mesoderm core is a combination of what 2 layers?
2. What does it form?
- Lateral plate and cranial paraxial mesoderm
2. Muscle cell bodies
- What forms the cervical sinus? Is cervical sinus permanent or temporary?
- All pharyngeal grooves/closing membranes are obliterated except?
- The second arch growing over the more caudal grooves; should be temporary
- The ones associated with arch 1
- What happens if cervical sinus is not temporary?
- How will an external cyst present?
- 3 possible sites of cervical cysts/fistulas?
- It forms a cervical cyst; place where second arch grew over and sinus never closed up
- Pus will come out of your neck
- On face right next to ear, medial to middle of SCM muscle, medial to where SCM inserts to sternum
What provides sensory innervation to 1st arch? Motor?
Sensory= V2 Motor= V3
- What branch of vagus nerve innervates 4th arch?
2. 6th?
- Superior laryngeal nerve
2. Recurrent laryngeal nerve
Cartilaginous derivatives of each arch:
- First (3)
- Second (5)
- Third (2)
- Fourth/sixth (1)
- Mandible, malleus, incus
- Stapes, styloid process, stylohyoid ligament, lesser horn and upper body of hyoid
- Greater horn and lower body of hyoid
- Laryngeal cartilages
What is the precursor for the mandible?
Meckels cartilage
Muscle groups of the arches:
- 1st (5)
- 2nd (3)
- 3rd (1)
- 4th/6th (2)
- Muscles of mastication, anterior digastric, mylohyoid, tensor tympani and tensor veli palatini
- Muscles of facial expression, posterior digastric, stylohyoid
- Stylopharyngeus
- Muscles of larynx and pharynx
All arches come from 1st somitomere except for? Which comes from?
4th/6th - 1st occipital somite
Arteries of the following:
- 3rd arches
- Right 4th arch
- Left 4th arch
- 6th arches
- Internal and external carotid
- Brachiocephalic trunk and right subclavian
- Aortic arch and left subclavian
- Pulmonary arteries (and ductus arteriosus on left)
Derivatives of the pharyngeal pouches:
- 1st pouch
- 2nd pouch
- 3rd pouch
- 4th pouch
- Middle ear and eustachian tube
- Palatine tonsil
- Inferior parathyroid and thymus
- Superior parathyroid and ultimobranchial body (C cells of thyroid)
Ear formation: derivatives of the following:
- 1st groove
- 1st closing membrane
- 1st pouch
- External acoustic meatus
- Tympanic membrane
- Middle ear and eustachian tube (repeat)
- Air chamber in the head comes from?
- Hyomandibular joint evolved into?
- Articular/quadrate joint evolved into? What kind of cartilage?
- TMJ is between 2 __ bones. What kind of cartilage?
- First pharyngeal pouch
- Stapes
- Incus and malleus; hyaline
- Membrane; fibrocartilage
Name 3 unpaired structures that develop from floor of pharynx
Thyroid, larynx, and tongue
Tongue derivation has what 3 parts
Distal tongue bud, median tongue bud, and hypobranchial eminence
Site of development for thyroid?
Foramen cecum
How is the larynx developed?
As an outpocketing from pharyngeal floor
Tongue is derived from every arch except?
However, a branch of this arch __, persists to do what?
2nd
Chorda tympani persists to provide taste to anterior 2/3
Thyroid development begins where and migrates where?
So along this course, what is possible?
Develops in back of tongue and descends to front of trachea
Ectopic thyroid is possible
What happens if the thyroglossal duct does not degenerate?
Communication between mouth and thyroid will occur
- Which pouch has the tonsil?
2nd pouch