Embryology Flashcards
What structures are derived from endoderm?
Epithelial lini of digestive and respiratory tract
Lining of urethra, bladder reproductive system
Liver
Pancreas
Which structures are derived from mesoderm?
Notochord
Musculoskeletal system
Muscular layer of viscera
Circulatory system
Which structures are derived from ectoderm?
Epidermis of skin
Cornea and lens
Nervous system
When does granulation occur?
Week 3
Which embryological structure forms the paired spinal nerves?
Somites
How many pairs of spinal nerves are there?
31
Which structure do the ribs and vertebrae form from?
Sclerotome
Which structure are somites formed from?
Paraxial mesoderm
Which structure is formed from the dorsal portion of the somite?
Dermomyotomes
C5 myotome
Shoulder abduction
Elbow extension myotome
C7
Finger abduction myotome
T1
C8 myotome
Finger flexion
C6 myotome
Elbow flexion
L2 myotome
Hip flexion
L3 myotome
Knee extension
Ankle dorsiflexion myotome
L4
L5 myotome
Great toe extension
S1 myotome
Ankle plantarflexion
By which day has the trimlaminar disc formed?
20
Do upper or lower limbs develop first?
Upper
When are the limbs well differentiated?
Week 8
What is amelia?
Congenital absence of one or more limbs
What is meromelia?
Partial absence of one or more limb structures
What is syndactyly?
Fusion of digits
What is polydactyly?
Increased number of digits
When is development of the face complete?
6 weeks
When are the nasal and oral cavities distinct from one another?
12th week
How many pharyngeal arches are there?
6
Which three structures are associated with each pharyngeal arch?
Branch of aorta
Cranial nerve
Cartilage bar
What causes cleft lip?
Failure of the medial nasal prominence to fuse with the maxillary prominence
What causes cleft palate?
Failure of the palatal shelves to fuse in the midline
What is the primitive mouth called?
Stomatodeum
Name the six regions of the primitive heart tube
Aortic roots
Truncus arteriosus
Bulbus cordis
Ventricle
Atrium
Sinus Venosus
1st and 2nd aortic arch
Maxillary, hyoid and stapedial arteries
3rd aortic arch
Common carotid artery
Part of the proximal internal carotid artery
4th aortic arch
Right - right subclavian
Left - arch of aorta
5th aortic arch
Never forms or incompletely forms and regresses
6th aortic arch
Right - right pulmonary artery
Left - left pulmonary artery and ductus arteriosus
Which arches do the left and right RLNs hook under?
Right - 4th arch - right subclavian artery
Left - 6th arch - ductus arteriosum
Which structures are connected by the ductus venosus?
Umbilical vein and IVC
Which substance causes the ductus venosus to close at birth?
Bradykinin
What is the adult remnant of the umbilical vein?
Ligamentum teres
Which primitive structure gives rise to the kidneys?
Urogenital ridge
Which structure is the collecting system of the kidney derived from?
Ureteric bud
Which structure is the excretory system of the kidney derived from?
Metanephric blastema
Where are accessory renal arteries found?
Pelvis
Which vessel would a horseshoe kidney be found underneath?
Inferior mesenteric artery
Which structure originally drains the urinary bladder in the foetus?
Allantois
What is the remnant of the allantois called?
Urachus
In adults, what is the name given to the remnant of the urachus?
Median umbilical ligament
What structure is formed by the mesonephric (Wolffian) ducts in men?
Ejaculatory ducts
What causes the mesonephric ducts to degenerate in women?
Lack of testicular androgens
Which structure arises from the 1st pharyngeal cleft?
External auditory meatus
What does the first pharyngeal arch form?
All the muscles innervated by the trigeminal nerve
Maxilla, zygoma, temoral bone
Maxillary artery
Malleus, incus
Which embryological arteries are associated with the second pharyngeal arch?
Stapedial artery
Hyoid artery
Which structures are formed by the cartilage of the second pharyngeal arch? (Reicherts cartilage)
Stapes
Styloid process
Stylohypoid ligament
Upper bost and lessor horns of hyoid
Which nerve is associated with the second pharyngeal arch?
Facial
Which artery is formed from the third pharyngeal arch?
Common carotid artery
What is formed from the cartilage of the 3rd pharyngeal arch?
Lower bodt and greater horn of hyoid
Which nerve is associated with the third pharyngeal arch?
Glossopharyngeal
Which muscle is formed from the third pharyngeal arch?
Stylopharyngeus
Which arteries are formed from the 4th pharyngeal arch?
Right - proximal portion of subclavian artery
Left - aortic arch
Which structured are formed from the cartilage of the 4th pharyngeal arch?
Laryngeal cartilages
Which nerve is associated with the 4th pharyngeal arch?
Superior laryngeal branch of the vagus
Which arteries are formed by the 6th pharyngeal arch?
Right - proximal pulmonary arteries
Left - ductus arteriosus
Which nerve is associated with the 6th pharyngeal arch?
Recurrent laryngeal branch of the vagus
Which structures are derived from the 1st pharyngeal pouch?
Eustachion tube
Middle ear cavity
Which structures are derived from the 2nd pharyngeal pouch?
Lining of the palatine tonsils
Which structures are derived from the 3rd pharyngeal pouch?
Dorsal - inferior parathyroid glands
Ventral - thymus
Which structures are derived from the 4th pharyngeal pouch?
Dorsal - superior parathyroid glands
Ventral - C cells of thyroid
Where are brachial/pharyngeal cysts found?
Anterior border of SCM
Which structure in the embryo becomes the anterior pituitary?
Rathke’s pouch
Which structure in the embryo becomes the posterior pituitary?
Infundibulum
Which cells in the alveoli produce surfactant?
Type II pneumocytes
Which gene stimulates the primitive sex cords to form testis cords?
SRY gene on Y chromosome
Which structure is formed from the testis cords in puberty?
Seminiferous tubules
Which cells in the testis cords produce testosterone?
Leydig cells
What do the mesonephric ducts become in males?
Efferent ductules
Epididymis
Vas deferens
Seminal vesicles
What happens to the paramesonephric ducts in males and why?
Degenerate due to anti-Mullerian hormone produced by sertoli cells in the testes
What is the appendix testes a remnant of?
Paramesonephric ducts (Mullerian)
What is the remnant of the mesonephric ducts in females?
Gartner’s duct
What do the paramesonephric ducts form in females?
Fallopian tubes
Uterus
Cervix
Upper portion of vagina
What causes bicornuate uterus?
Incomplete fusion of the paramesonephric ducts
What causes hypospadias?
Incomplete closure of the urethral folds
What is the remnant of the gubernaculum in males?
Scrotal ligament
What is the remnant of the gubernaculum in females?
Ovarian ligament
Round ligament of uterus