Lecture 9 - Branchial Arch Embryology Flashcards
What is the stomatodeum?
The primitive oral cavity
What is the stomatodeum lined with?
Surface ectoderm
Where does the stomatodeum form?
Between the developing brain & heart
What are the derivatives of the Stomatodeum?
oral mucosa, lips, gingiva, enamel, anterior pituitary gland
What lines the primitive pharynx?
Endoderm
What separates the primitive pharynx from the stomatodeum?
The bucopharyngeal membrane
Where is the level of ectoderm-endoderm junction in adults?
Oral fauces (arches)
What is Rathke’s pouch?
An ectodermal (surface) outpocketing from the stomatodeum
What does Rathke’s pouch form?
The anterior pituitary gland (adenohypophysis)
What does the posterior pituitary (neurohypophysis) form from?
neural tube
Dental lamina
Thick line of surface ectoderm along mandible & maxilla
Dental buds
ectodermal primordial, forms enamel
Dental papillae
neural crest derived mesenchyme, forms dentin and pulp
When do teeth begin to form?
Week 6
3 types of ectoderm
Surface ectoderm, neural tube, and neural crest cells
4 types of mesoderm
Axial mesoderm, paraxial mesoderm, intermediate mesoderm, and lateral plate mesoderm
What forms from the surface ectoderm in the branchial arches?
Oral and nasal mucosa, parotid gland, and enamel
What forms from the neural tube in the branchial arches?
Brain, olfactory bulb, and retina of the eye
What forms from the neural crest cells in the branchial arches?
Facial bones and cartilage, hyoid, and dentin
What forms from the paraxial in the branchial arches?
Skeletal muscle (somite) and the occipital bone
What forms from the lateral plate mesoderm in the branchial arches?
Laryngeal cartilages
What forms from the endoderm in the branchial arches?
Pharyngeal & laryngeal epithelium, taste buds, parathyroid & thymus glands, and the submandibular & sublingual glands
How many arches form around the visceral tube?
6
Neural crest cells make up which branchial arches?
arches 1-3
Lateral plate mesoderm makes up what branchial arches?
arches 4 & 6
What does the 5th branchial arch form?
Nothing, it degenerates
What do the cranial somites form?
Extrinsic eye muscles
What do the occipital somites form?
Tongue muscles
What do the branchial arches form?
Myoblasts from the cranial & occipital somites, and the muscles of the head & neck
What are the cranial nerves and the modality of the cranial somites?
CN III, IV, VI
GSE
What are the cranial nerves and the modality of the occipital somites?
CN XII
GSE
What are the cranial nerves and the modality of the branchial arches?
CN V, VII, IX, X, and XIc
SVE
Pharyngeal pouch
Inside branchial arches, lines with endoderm
Pharyngeal cleft
Outside branchial arches, lined with surface ectoderm
What forms the cervical sinus?
fused pharyngeal clefts 2-4
What forms from aortic arch 4?
left aortic arch and right brachiocephalic artery
What forms from aortic arch 6?
left ligamentum arteriosum and the recurrent laryngeal nerve
What are the three developmental layers of the skull?
Viscerocranium, Membranous Neurocranium, Neural Chondocranium
Where does the viscerocranium form from?
Branchial arch-related neural crest
What does the viscerocranium form?
mandible, maxilla zygoma, hyoid
Where does the membranous neurocranium form from?
Neural crest and somites (sclerotome)
What type of bones are in the membranous neurocranium?
flat bones of the braincase
How does the membranous neurocranium form?
intramembranous ossification
What are examples of bones that form from the membranous neurocranium?
The frontal bone, parietal bone, and occipital bones
Where does the neural chondocranium form from?
Neural crest and somites (sclerotome)
How does the neural chondocranium form?
Endochondral ossification
What does the sella turcica contain?
The hypophysis (pituitary gland)
Where does the basicranial bone posterior to the sella turcica derive from?
Sclerotome (somite)
Where does the basicranial bone anterior to the sella turcica derive from?
NCC
Where does the hyoid bone form from?
Neural crest cells
What makes up arch 2 from the hyoid bone?
The lesser horn & upper body
What makes up arch 3 from the hyoid bone?
The greater horn & lower body
Where do arches 4-6 form from?
Lateral plate mesoderm
What are the laryngeal cartilages?
Thyroid, cricoid, arytenoid, corniculate, cuneiform
What is the function of the tongue?
A muscular organ that aids in the ingestion of food
What are the modalities of the tongue?
Motor: GSE
Sensory: tactile - GSA
chemosensation/taste - SVA
Where do the muscles of the tongue develop from?
occipital somites (PAM)
What nerve innervates the tongue muscles?
Hypoglossal nerve (CN XII)
What are the two regions of the tongue?
Oral tongue (ant. 2/3) & Pharyngeal tongue (post. 1/3)
What structure marks the boundary between the two regions of the tongue?
Foramen cecum
What nerve innervates the oral tongue?
Trigeminal (CN X)
What nerve innervates the pharyngeal tongue?
Glossopharyngeal nerve (CN IX)
What are the lateral lingual swellings and what arch does they come from?
The mucosa of the anterior 2/3 of the tongue, Arch 1
What nerve innervates and what is the modality of the lateral lingual swellings?
Trigeminal (CN V), GSA
What are the medial lingual swellings?
Tuberculum impar, Hypobranchial eminence (copula lingulae), and the epiglottis
What arch does the tuberculum impar come from, what nerve innervates it, and what is its modality?
Arch 1, Trigeminal (CN V), GSA
What arch does the Hypobranchial eminence come from, what nerve innervates it, and what is its modality?
Arch 3, Glossopharyngeal (CN IX), GSA
What arch does the epiglottis come from, what nerve innervates it, and what is its modality?
Arch 4, Vagus (CN X), GVA
Where do taste buds develop from?
The endoderm lining of the branchial arches
What nerves carry taste and what is the modality for taste?
Facial (CN VII), Glossopharyngeal (CN IX), and Vagus (CN X), SVA
What arches are associated with the oral tongue and what nerves innervate it with innervation?
Arches 1-2, Sensation: Trigeminal (CN V) GSA, Taste: Facial (CN VII) SVA
What arches are associated with the pharyngeal tongue and what nerves innervate it with innervation?
Arch 3, Sensation: Glossopharyngeal (CN IX) GSA, Taste: Glossopharyngeal (CN IX) SVA
What arches are associated with the epiglottis and what nerves innervate it with innervation?
Arch 4, Sensation: Vagus (CN X) GVA, Taste: Vagus (CN X) SVA
Frontonasal prominence
forms the nasal placodes/pits (nasal cavities)
What surrounds the nasal placodes?
medial & lateral nasal swellings
What arch does both the maxillary and mandibular swellings come from?
Arch 1