Head and Neck Development Flashcards
All vertebrates form ______, which are also called: branchial arches
All vertebrates form pharyngeal arches, which are also called: branchial (“of the gill”) arches
When do the pharyngeal arches appear? How do they develop?
Appear by 4th week
Develop sequentially from cranial to caudal
SLIDE 4
Where are the pharyngeal arches positioned?
On either side of the developing pharynx
______ in the head and neck form the peripheral nervous system and melanocytes, same as in the trunk
Neural Crest Cells (NCCs) in the head and neck form the peripheral nervous system and melanocytes, same as in the trunk
Neural Crest Cells (NCCs) in the head and neck form the _______ and _______, same as in the trunk
Neural Crest Cells (NCCs) in the head and neck form the peripheral nervous system and melanocytes, same as in the trunk
In addition to forming the peripheral nervous system and the melanocytes, what else can neural crest cells in the head and neck form?
Connective tissue, including cartilage and bone
______ are expanded regions of tissue on either side of the pharynx
SLIDE 8
pharyngeal arches are expanded regions of tissue on either side of the pharynx
The pharyngeal arches are filled with _______, mostly derived from ______
Slide 8
The pharyngeal arches are filled with mesenchymal cells, mostly derived from neural crest
What are pharyngeal pouches?
Pockets of endoderm between the pharyngeal arches
Pharyngeal arches develop _____ over the 4th week
Pharyngeal arches develop craniocaudally over the 4th week
Which pharyngeal arch is never externally visible and will regress?
Arch 6
What are the two parts of pharyngeal arch 1?
- Maxillary prominence
- Mandibular prominence
The 6th arch starring role is _______, otherwise it is often lumped with arch ____
The 6th arch starring role is ductus arteriosus, otherwise it is often lumped with arch 4
What are the three elements of the Pharyngeal Apparatus?
- Pharyngeal arches
- mesenchymal swellings (mostly from neural crest)
- Pharyngeal pouches
- outpocketings in internal aspect of pharynx separating adjacent pharyngeal arches
- Endodermal
- Pharyngeal Clefts/Grooves
- external aspect separating adjacent arches
- Ectodermal
- external aspect separating adjacent arches
- Pharyngeal arches
- ________
- Pharyngeal pouches
- __________
- _______
- Pharyngeal Clefts/Grooves
- ___________
- Pharyngeal arches
- mesenchymal swellings (mostly from neural crest)
- Pharyngeal pouches
- outpocketings in internal aspect of pharynx separating adjacent pharyngeal arches
- Endodermal
- Pharyngeal Clefts/Grooves
- external aspect separating adjacent arches
- Ectodermal
- external aspect separating adjacent arches
What is the red circle in the image?
- Pharyngeal Membrane
- where endoderm and ectoderm meet
Each pharyngeal arch contains: (5)
- Mesenchyme
- Forms bones of viscerocranium (dermal bones)
- Mainly neural crest
- Cartilage
- Skeleton of arch
- Mainly neural crest
- Muscle
- Form muscles of face and neck
- paraxial mesoderm
- Nerve
- innervation to muscle and mucosa of arch
- cranial nerve for each arch
- innervation to muscle and mucosa of arch
- Arch Artery
- Blood supply of arch
Each pharyngeal arch contains:
- Mesenchyme
- Forms _________
- Mainly _______
- Cartilage
- _______
- Mainly ______
- Muscle
- Form ________
- ________
- Nerve
- innervation to _________
- _______ for each arch
- innervation to _________
- Arch Artery
- _______
- Mesenchyme
- Forms bones of viscerocranium (dermal bones)
- Mainly neural crest
- Cartilage
- Skeleton of arch
- Mainly neural crest
- Muscle
- Form muscles of face and neck
- paraxial mesoderm
- Nerve
- innervation to muscle and mucosa of arch
- cranial nerve for each arch
- innervation to muscle and mucosa of arch
- Arch Artery
- Blood supply of arch
_______ populate the arches
1st arch receives ______ and ________
other arches receive _______
neural crest cells populate the arches_______ populate the arches
1st arch receives midbrain and hindbrain neural crest
Other arches receive hindbrain neural crest
________ develops around 1st arch cartilage (called _______) in the _________ via _________ ossification
Mandible develops around 1st arch cartilage (called meckels cartilage) in the mandibular prominence (forms lower jaw) via intramembranous ossification (dermal bone)
Anterior portion of meckels cartilage will _______
Posterior portion will form the _______ and the _______
Anterior portion of meckels cartilage will degenerate
Posterior portion will form the sphenomandibular ligament and the malleus (ear ossicle)
meckels cartilage is the cartilage of the 1st arch
Maxillary cartilage forms ______
Maxillary cartilage forms incus
Where do the stapes and superior body+lesser cornu of hyoid bone develop from?
Proximal portion of Reichert’s cartilage (2nd arch)
The hyoid bone is formed from:
- 2nd Arch Cartilage (Reichert’s cartilage)
- Superior body
- Lesser cornu
- 3rd Arch
- Inferior body
- Greater cornu
Middle portion of Reischerts cartilage (arch 2) makes ________
Middle portion of Reischerts cartilage (arch 2) makes Styloid process
The 2nd arch cartilage (Reicherts cartilage) gives rise to two bones (_____ and _____) and the ligament (______) between them
The 2nd arch cartilage (Reicherts cartilage) gives rise to two bones (styloid process and (part of) hyoid bone) and the ligament (stylohyoid ligament) between them
What is eagles syndrome?
Elongated styloid process; can happen congenitally or later; ossification of ligament
4th/6th arches form _________ cartilages (2)
4th/6th arches form laryngeal cartilages
- Thyroid cartilage
- Cricoid cartilage
What are branchial vestiges?
- Branchial vestiges are cartilage or bony remnants from the arch cartilages that fail to disappear through regression and remodelling and therefore remain under the skin
Muscles formed by Arch 1:
- Muscles of mastication
- Mylohyoid
- Anterior belly of digastric
- Tensor tympani
- Tensor veli palatini
Muscles formed by Arch 2: (4)
- Muscles of facial expression
- Posterior belly of digastric
- Stylohyoid muscle
- Stapedius
Muscles formed by 3rd arch: (1)
- Stylopharyngeus muscle
Muscles formed by 4th/6th arches: (3)
- Constrictors of pharynx
- Cricothyroid
- Intrinsic muscles of larynx
Label the mm formed by the 1st arch
Label the muscles formed from the 2nd arch
Label the muscles formed from the 2nd arch
Label the mm formed by the 3rd arch (1)
Label the mm formed by the 4th/6th arches (3)
** intrinsic mm of larynx are deeper
Pharyngeal arch nerves:
- Arch 1
- Arch 2
- Arch 3
- Arch4/6
Pharyngeal arch nerves:
- Arch 1
- Cranial nerve V (trigeminal nerve)
- Maxillary and mandibular parts get their own nerve
- V1 - opthalamic
- V2 - Maxillary
- V3 - Mandibular (only one with motor)
- Arch 2
- Facial nerve VII
- Arch 3
- Glossopharyngeal nerve
- IX
- Arch4/6
- Vagus nerve
- X
Aortic arches connect ______ to ______
Aortic arches connect aortic sac (attached to heart) to dorsal aortae
RECALL: AORTIC ARCH REMODELLING
- third arch becomes
- Fourth arch becomes
- left
- right
- sixth aortic arch forms _____
RECALL: AORTIC ARCH REMODELLING
- third arch becomes common carotid arteries
- Fourth arch becomes
- left: arch of aorta
- right: right subclavian artery
- sixth aortic arch forms ductus arteriosus (LEFT)
ALL START IN PHARYNGEAL ARCHES
Pharyngeal Pouches:
- there are ______ pouches separating the arches
- These develop ______
- ________-lined pockets
Pharyngeal Pouches:
- there are 4, well-developed pouches separating the arches
- These develop cranio-caudally
- endoderm-lined pockets
Pharyngeal pouches form ________
- 2nd pouch:
- makes _______
- 3rd pouch:
- _______
- 4th pouch
- _________
Pharyngeal pouches form solid structures
- 2nd pouch:
- makes palatine tonsils
- endoderm proliferates and forms stroma of palatine tonsils at back of mouth
- 3rd pouch:
- inferior parathyroid glands and thymus
- endoderm proliferates → stroma of thymus → support for T4 cells (colonized by immune)
- 4th pouch
- superior parathyroid glands and ultimobranchial body
- ultimobranchial body becomes integrated into thyroid
The thyroid originates from _______ on the floor of the ______
The thyroid originates from endoderm on the floor of the pharynx
Develops in Tongue and relocates
As the thyroid gland descends, it leaves behind a _________ (temporary structure)
As the thyroid gland descends, it leaves behind a thyroglossal duct (temporary structure)