Lecture 18: Development of Pharyngeal Arches Flashcards
What are the 3 principle components of the pharyngeal complex?
Pharyngeal arches, clefts, and pouches
Name the type of tissue that migrates from the 1st and 2nd pharyngeal arches into the developing face
Neural-crest derived mesenchyme
From which embryonic germ layer do muscles develop?
Mesoderm
What type of cells give rise to the facial skeleton and coronal and sagittal sutures?
Neural crest cells
What gives rise to the posterior neurocranium and basicranium?
Mesoderm
Which pharyngeal arch gives rise to Meckel’s cartilage, malleus, incus, mandible, and maxilla?
Pharyngeal arch 1
Fusion of which prominences is required for the normal development of the upper lip?
Nasomedial, nasolateral, and maxillary prominences
What facial abnormality is the result of failure of the nasomedial and maxillary prominences to fuse?
Cleft lip
What is the problem underlying cleft palate?
Problem with nasomedial segments fusing
What are the muscular components of pharyngeal arch 1?
Muscles of mastication - temporalis, masseter, mylohyoid, anterior belly of digastric
What are the muscular components of pharyngeal arch 2?
Muscles of facial expression - buccinator, orbicularis oris, posterior belly of digastric, platysma, frontalis, orbicularis oculi, occipitalis
What are the muscular components of pharyngeal arch 3?
Stylopharyngeus
What are the muscular components of pharyngeal arches 4 and 6?
levator veli palatini, pharyngeal muscles, intrinsic muscles of larynx
What are the nerve components of pharyngeal arch 1?
Trigeminal nerve (CN V) - specifically mandibular division (V3)
What are the nerve components of pharyngeal arch 2?
Facial nerve (CN VII)
What are the nerve components of pharyngeal arch 3?
Glossopharyngeal nerve (CN IX)
What are the nerve components of pharyngeal arches 4 and 6?
Vagus nerve (CN X)
What structures does the frontonasal prominence form?
forehead, bridge of nose, medial/lateral nasal prominences
What structures does the maxillary prominence form?
cheeks, lateral portion of upper lip
What structures does the medial nasal prominence form?
Philtrum of upper lip, crest/tip of nose
What structures does the lateral nasal prominence form?
Alae of nose
What structures does the mandibular prominence form?
Lower lip
When are BMPs expressed and what is their function in development of facial structures?
Early expression; induce superficial location of palatal shelves
What is the function of Shh in induction of facial development?
Early induction of facial primordia; medial edge epithelial of palatal shelves (fusion of epithelium)
What is the function of Tbx22 in facial development?
Ensures mobility of tongue and allows tongue to move and make way for palatal shelf fusion
Ankyloglossia
Mutations in Tbx22 - immobile tongue
Median cleft lip
Incomplete merging of two medial nasal prominences; leads to forms of bifid nose
What is the primary feature of a complete bilateral cleft palate?
Premaxilla is unattached, grows forward
Macrostonia
“Large mouth”; hypoplasia or incomplete fusion of maxillary and mandibular prominences
Treacher-Collins Syndrome, Pierre Robins Syndrome
Classic arch 1 abnormalities; deficiency in formation of facial skeleton
Which pharyngeal arch gives rise to Reichert’s cartilage, stapes, styloid process, lesser horns and superior portion of hyoid bone?
Pharyngeal arch 2
Which pharyngeal arch gives rise to greater horns and inferior portion of hyoid bone?
Pharyngeal arch 3
Which pharyngeal arch gives rise to the laryngeal cartilages?
Pharyngeal arches 4 and 6
Which aortic arch contributes to maxillary arteries?
Aortic arch I
Which aortic arch produces stapedial and hyoid arteries?
Aortic arch II
Which aortic arch contributes to common carotid arteries and internal carotid arteries?
Aortic arch III
Which pharyngeal cleft is the external auditory meatus derived from?
Pharyngeal cleft I
Which pharyngeal cleft is the neck derived from?
Pharyngeal cleft II, III, and IV
Which aortic arch gives rise to the right subclavian artery and aorta?
Aortic arch IV
Which pharyngeal pouch is the middle ear and auditory tube derived from?
Pharyngeal pouch I
Which pharyngeal pouch is the supra-tonsillar fossa derived from?
Pharyngeal pouch II
Which pharyngeal pouch is the thymus and parathyroid gland derived from?
Pharyngeal pouch III
Which pharyngeal pouch is the thymus, parathyroid gland, ultimobranchial body formed from?
Pharyngeal pouch IV (and V)
Cervical cysts/fistulas
Result of remnants of pharyngeal clefts 2-4 along border of sternocleidomastoid muscle
DiGeorge Syndrome
Group of disorders which share a common microdeletion on chromosome 22. Characterized by hyoparathyroidism, hypocalcemia, underdeveloped/absent thymus, heart defects; may also involve delays in speech/learning development
From which pharyngeal arches does the tongue arise?
Pharyngeal arches 1, 2, and 3
Sulcus terminalis of tongue
Site of union between the base and body of the tongue, delineated by V-shaped groove
Name the sensory and taste bud innervations of the anterior 2/3 of the tongue
Sensory: lingual nerve (branch of trigeminal)
Taste buds: facial nerve (chorda tympani)
Name the sensory and taste bud innervations of the posterior 1/3 of the tongue
Sensory: glossopharyngeal nerve (CN IX)
Taste buds: glossopharyngeal nerve, vagus nerve
From what structure does the thyroid originate?
Thyroid diverticulum
Ectopic thyroid tissue
Anomaly in thyroid development where thyroid tissue is present along the course of thyroglossal duct
Thyroglossal duct fistula
Rupturing of a thyroglossal duct cyst presenting as a draining sinus
