Embryology of Resp. System Flashcards
What week does gastrulation occur?
Week 3
Which 2 layers of the germ layer are most important for the development of the resp. system?
Endoderm and mesoderm
What does the endoderm form and what does the mesoderm form?
Endoderm: Epithelial lining and glands
Mesoderm: muscles, cartilage, connective tissue
What is needed for the appearance and location of the lung bud and what is it’s importance?
Retinoic acid: It is needed for the upregulation of the transcription factor TBX4 expressed in the gut tube
What is the role of TBX4?
Induces formation of lung bud and its continued growth and differentiation
How many pharyngeal arches , pouches, and clefts are there and where do they derive from?
5 pharyngeal arches: mesoderm
4 pouches: endoderm
4 pharyngeal clefts/grooves: ectoderm
What structure is derived from the 1st pharyngeal arch?
Mandibular (maxillary and mandibular processes)
What are the nerve supply derivatives of the 1st arch?
CN V : Trigeminal–> maxillary and mandibular divisions
What are the muscles of the 1st pharyngeal arch?
(MMATT)
Mastication (temporal, masseter, medial, lateral, pterygoids), Mylohyoid, Anterior belly of digastric, Tensor Palatine, Tensor tympani
What are the skeletal derivatives of the 1st pharyngeal arch
Premaxilla, maxilla, zygomatic bone, part of temporal bone, meckel cartilage, mandible malleus, incus, anterior ligament of malleus, sphenomandibular ligament
what is the derivative of the 2nd pharyngeal arch?
Hyoid
What is the nerve innervation from the 2nd pharyngeal arch?
Facial- CN7
What are the muscle derivatives of 2nd arch?
(Face posteriorly, side by side)
Facial expression (buccinator, auricularis, frontalis, platysma, orbicularis oris, orbicularis oculi), posterior belly of digastric, stylohyoid, stapedius
What is the nerve innervation from the 3rd pharyngeal arch?
Glossopharyngeal -CN IX
What is the muscle derivative of 3rd pharyngeal arch?
Stylopharyngeus
What are the skeletal derivatives of the 3rd pharyngeal arch?
Greater horn and lower portion of body of hyoid bone
What are the skeletal derivatives of the 2nd pharyngeal arch?
stapes, styloid process, stylohoid ligament, lesser horn and upper portion of body of hyoid
What are the nerve derivatives of the 4th and 6th pharyngeal arches?
Vagus-X
4th: Superior laryngeal branch
6th: Recurrent laryngeal branch
What are the muscle derivatives of the 4th arch?
cricothyroid, levator veli palatini, constrictors of pharynx
What are the muscle derivatives of the 6th arch?
Intrinsic muscles of larynx
What are the skeletal derivatives of the 4th and 6th arch?
laryngeal cartilages: thyroid, criciod, arytenoid, corniculate, cuneiform
Which week does the trachea and lung develop ? Explain what happens during this week.
4th week
Edothelial cells coming off foregut forms lung bud. Tracheoesophageal groove forms, Bronchial bud forms, and tracheoesophageal septum forms
Which arches do the muscles and cartilage derive from?
4th and 6th
Explain role of tracheoesophageal septum
Separates the anterior lung bud (resp. diverticulum) from the posterior foregut
What takes place during week 5 of tracheal and lung development?
Tracheoesophageal septum closes
Endoderm from gut tube forms glands and epithelial lining
Splanchnic mesoderm forms muscles, cartilage, and CT
Stages of lung development starts
______ is the abnormal communication between trachea and esophagus due to defective development of the tracheoesophageal septum. May be associated with esophageal atresia
Tracheoesophageal fistula
-sometimes seen when the esophagus ends blindly