3 - Head and Neck Embryology (complete) Flashcards
what does the pharyngeal apparatus consist of
arches, pouches, grooves, membrane
What has the genetic code for development and migrates into the head and neck region at the beginning of the development of the pharyngeal arches
neural crest cells
where do the neural crest cells come from
they develop as a portion of the neural plate and migrate from the dorsal part of the body to the ventral part of the body
where does the stomadeum develop from
it forms as an invagination of ectoderm between the maxillary and mandibular prominences of the first arch
what separates the ectoderm lined stomadeum and the endoderm lined primitive pharynx
buccopharyngeal membrane
What is the nerve, artery, cartilage, and muscle group of the first pharyngeal arch,
N = trigeminal nerve V A = Maxillary artery C = Maxillary and mandibular (meckels cartilage) malleus and incus Muscle = Mastication muscles
What is the nerve, artery, cartilage, and muscle group of the second pharyngeal arch,
N = Facial Nerve VII A = Stapedial artery (embryonic) corticotympanic C = Reichert's Cartilage, stapes, styloid process, stylohyoid ligament, lesser horn of hyoid M = stapedius, stylohyoid, post. digastric, auricular, muscles of facial expression
What is the nerve, artery, cartilage, and muscle group of the third pharyngeal arch,
N = Glossopharyngeal Nerve IX A = carotid artery C = Greater horn of hyoid M = Stylopharyngeus
What is the nerve, artery, cartilage, and muscle group of the fourth pharyngeal arch,
N = Vagus nerve X A = part of aorta and R subclavian artery C = Thyroid cartilage M = cricoid thyroid, levator veli palatini, and constrictor of pharynx
What is the nerve, artery, cartilage, and muscle group of the sixth pharyngeal arch,
N = Vagus nerve X A = pulmonary artery roots C = cricoid cartilage M = intrinsic muscles of the larynx
What do the clefts 1-4 develop into
cleft 1 = external auditory meatus
cleft 2-4 = overlapped by the overgrowth of arch 2, but develops into the cervical sinus
What causes a cervical cyst and where are they located
a cervical cyst is caused by a cervical sinus that doesn’t resorb, it forms on the lateral border of the neck, just anterior to the sternocleidomastoid
What do the pouches develop into
1 = pharyngotympanic tube 2 = palatine tonsil 3 = inferior parathyroid gland and thymus 4 = superior parathyroid gland and ultimobrachial bodies
what do ultimobrachial bodies turn into
it turns into the follicular cells (C-cells) of the thyroid that produce calcitonin
How does the thyroid form
at the midline just below the tuberculum impar the primitive thyroid invaginates through the foramen cecum, migrates through the thyroglossal duct
what is a thyroglossal duct cyst and where is it located
it is when the thyroglossal duct doesn’t resorb leaving a pocket at the midline of the neck
How does the tongue develop
the anterior 2/3 of the tongue develop from the lateral lingual swellings and the tuberculum impar (1st arch)
the posterior 1/3 of the tongue develop from the copula/hypobranchial eminence (3rd arch)
From where do the muscles of the tongue originate
occipital somites
how many cranial and facial bones are there
8 cranial bones
14 facial bones
How do the eyes form
- optic placode forms
- optic placode moves anteriorly
- optic placode stops at the anterior face
How do the ears form
- auricular hillocks form (3 from arch one, 3 from arch 2)
- auricular hillocks and Ext. Aud. Meatus migrate to otic placode
- hillocks and meatus combine to form the ear
how does the nose form
- nasal placode forms with lateral and medial nasal processes
- medial migration and formation of nasolacrimal groove
- philtrum forms
What is the neurocranium and viscerocranium
neurocranium is the part of the skull that encases the brain, with the bones formed from both neural crest cells and mesoderm
Viscerocranium is the facial bones that are formed only from the neural crest cells
What bones make up the viscerocranium (8)
mandible, maxilla, zygomatic, vomer, palatine, lacrimal, nasal, and conchae
What bones make up the neurocranium, and which are Neural crest cell derived, and which are mesodermally derived
temporal (squamous portion), sphenoid, ethmoid, frontal (NCC)
temporal (petrous portion), occipital, parietal (mesoderm)
What are sutures and fontanelles
sutures are non-movable joints between bones of the skull
fontanelles are sutures that haven’t fused yet
what is cranioschisis
when the cranial vault fails to form
what is craniosynostosis
when one of more of the cranial sutures closes early
how does the nasal cavity form
- a nasal pit (ectoderm invagination) forms in the middle of the medial and lateral nasal prominences
- nasal pit moves dorsally
- prominences merge and form a nasal sac
- nasal sac invaginates dorsally (with stomadeum)
5 oronasal membrane degrades leaving the choanae, and the primary palate
How does the palate form
- intermaxillary segment/median palatine process/primary palate forms the anterior most portion
- lateral palatine shelves (secondary palate) and nasal septum grow inferiorly
- secondary palate fuses to first and starts to fuse like a zipper toward the distal
- mandibular growth allows tongue to get out of the way
- complete fusion
where is the primary palate found
from incisive foramen to distal lateral incisors
where is the secondary palate found
from the incisive foramen to the uvula
