Embryology - Part 3 Flashcards
What does cranial nerve V3 provide sensory innervation to?
Anterior 2/3 of the tongue
What does cranial nerve VII provide tast innervartion to?
Anterior 2/3 of the tongue
What does cranial nerve IX provide innervation to in the tongue?
Both sensory and taste innervation to posterior 1/3 of the tongue
What does crainal nerve X provide innervation to in the tongue?
Both sensory and taste innervation to extreme posterior 2/3 of the tongue
The malleus of the ear is formed from what fetal structure?
Branchial arch 1
The incus of the ear is formed from what fetal structure?
Branchial arch 1
The stapes of the ear is formed from what fetal structure?
Branchial arch 2
The tensor tympani muscle in the ear is derived from what fetal structure?
Branchial arch 1
The tensor tympani muscle in the ear is innervated by what nerve?
Cranial nerve V3
The stapedius muscle in the ear is derived from what fetal structure?
Branchial arch 2
The stapedius muscle in the ear is innervated by what nerve?
Cranial nerve VII
The external auditory meatus is derived from what fetal structure?
Branchial cleft 1
The tympanic membrane is derived from what fetal structure?
The first branchial membrane
The eustacian tube, middle ear cavity, and mastoid air cells are derived from what fetal structure?
The first brancial pouch
The anterior two thirds of the tongue are derived from which branchial arch?
Branchial arch 1
Sensation in the anterior two thirds of the tongue is mediated by which cranial nerve?
V3
Taste in the anterior two thirds of the tongue is mediated by which cranial nerve?
VII
The posterior third of the tongue is derived from which branchial arches?
Branchial arches 3 and 4
Sensation in the posterior third of the tongue is mediated by which cranial nerve?
IX; as well as taste
Taste in the posterior third of the tongue is mainly mediated by which cranial nerve?
IX; as well as sensation
Taste in the extreme posterior of the tongue is mediated by which cranial nerve?
X
True or False: Taste and sensation in the anterior two-thirds of the tongue are mediated by the same cranial nerve.
False; cranial nerve VII mediates taste, while sensation is mediated by CN V3
Taste in the anterior two thirds of the tongue is mediated by cranial nerve _____, whereas taste in the posterior third of the tongue is mediated by cranial nerve _____.
VII; IX
Sensation in the anterior two thirds of the tongue is mediated by cranial nerve _____, whereas sensation in the posterior third of the tongue is mediated by cranial nerve _____.
V3; IX
Which cranial nerve supplies motor innervation to the tongue?
XII
Which cranial nerves mediate the sense of taste?
VII, IX, and X
Cranial nerves that mediate the sense of taste project to the ______ nucleus.
Solitary
Which cranial nerves mediate the sense of pain in the tongue?
V3, IX, and X
True or False: The muscles of the tongue are derived from occipital myotomes.
True
Which cranial nerve mediates taste and sensation in the extreme posterior portion of the tongue?
CN X
Which cranial nerve mediates taste and sensation in most of the posterior third of the tongue, except for the extreme posterior portion?
CN IX
Which cranial nerve mediates taste in the anterior two thirds of the tongue?
CN VII
Which cranial nerve mediates sensation in the anterior two thirds of the tongue?
CN V3
True or False: The thyroid gland develops as a diverticulum of the gastrointestinal tract.
True; it arises from the floor of the primitive pharynx
What is the name of the structure that connects the thyroid gland with the tongue?
The thyroglossal duct
True or False: The thyroglossal duct usually persists into adulthood.
False; it normally disappears
The thyroglossal duct normally disappears during development, but it may persist as the ______ lobe of the thyroid.
Pyramidal
What is the name of the normal remnant of the thyroglossal duct?
The foramen cecum
What is the most common site of ectopic thyroid tissue?
The tongue
A thyroglossal duct cyst is commonly found and felt where?
In the midline neck
What happens to a thyroglossal duct cyst with swallowing?
It will move with swallowing, unlike a branchial cleft cyst
A persistent cervical sinus, leading to a branchial cyst, is commonly found and felt where?
In the lateral neck
A branchial cyst is commonly found in the _____ (lateral/midline) neck, while a thyroglossal duct cyst is commonly found in the _____ (lateral/midline) neck.
Lateral; midline
A _____ cyst is commonly found in the lateral neck, while a _____ cyst is commonly found in the midline neck.
Branchial; thyroglossal duct
Cleft lip results from the failure of which structures to fuse?
Maxillary nasal process and medial nasal process
Cleft palate results from failure of which structures to fuse?
The lateral palatine process, the nasal septum and the median palatine process
Cleft lip is a defect in the formation of the _____ (primary/secondary) palate, and cleft palate is a defect in the formation of the _____ (primary/secondary) palate.
Primary; secondary
What four structures contribute to the diaphragm?
The Septum transversum, the Pleuroperitoneal folds, the Body wall, and the Dorsal mesentery of the esophagus (remember: Several Parts Build Diaphragm)
True or False: The septum transversum contributes to the diaphragm.
True
True or False: The body wall does not contribute to the formation of the diaphragm.
False; the body wall does contribute to the diaphragm
What nerves innervate the diaphragm?
C3, C4, and C5 (remember: C3, 4, 5 keeps the diaphragm alive)
Does the diaphragm ascend, descend, or form in situ during development?
It descends from its original formation to its final location in the body
A neonate has an x-ray of the chest that shows abdominal contents in the chest cavity. This defect is likely the result of the incomplete development of the _____, resulting in a congenital _____ _____.
Diaphragm; diaphragmatic hernia
True or False: A diaphragmatic hernia can lead to hypoplasia of thoracic organs due to space compression.
True
What does the septum transversum become in the mature diaphragm?
The central tendon
What does the dorsal mesentery become in the mature diaphragm?
The diaphragmatic crura
Name 3 findings seen with a congenital diaphragmatic hernia.
Hypoplasia of thoracic organs, scaphoid abdomen, and cyanosis
In embryologic terms, what part of the gastrointestinal tract is derived from the foregut?
The pharynx to the duodenum
In embryologic terms, what part of the gastrointestinal tract is derived from the midgut?
The duodenum to the transverse colon
In embryologic terms, what part of the gastrointestinal tract is derived from the hindgut?
The distal transverse colon to the rectum
In embryologic terms, from what part of the gastrointestinal tract is the area between the pharynx and the duodenum derived?
The foregut
In embryologic terms, from what part of the gastrointestinal tract is the area between the duodenum and the transverse colon derived?
The midgut
In embryologic terms, from what part of the gastrointestinal tract is the area between the distal transverse colon and the rectum derived?
The hindgut
In fetal development, _____ is due to the failure of lateral body folds to fuse and the extrusion of abdominal contents outside the body wall.
Gastroschisis
True or False: Gastroschisis results in extrusion of abdominal contents though abdominal folds.
True
True or False: Gastroschisis is a failure of midline fusion.
True
An _____ is the persistence of herniated abdominal contents into the umbilical cord.
Omphalocele
Omphalocele is the persistence of herniated abdominal contents into the _____.
Umbilical cord
True or False: Tracheoesophageal fistulas are abnormal connections between the esophagus and trachea.
True
What is the most common subtype of tracheoesophageal fistula?
A blind pouch upper esophagus with the lower esophagus connected to the trachea
What are some symptoms seen with the most common subtype of tracheoesophageal fistula?
Cyanosis, choking and vomiting with feeding, air bubble on x-ray of the chest, and polyhydramnios
A newborn is noted to choke and vomit with routine feedings; the mother had polyhydramnios during pregnancy; what is the most likely diagnosis?
Tracheoesophageal fistula
In what disease is there hypertrophy of the pylorus?
Congenital pyloric stenosis
In congenital pyloric stenosis, hypertrophy of the pylorus leads to what problem?
Obstruction
What are the two classic findings in an infant with congenital pyloric stenosis?
A palpable epigastric olive-sized mass and projectile vomiting
Where is the “olive” mass typically palpated in a patient with congenital pyloric stenosis?
In the epigastric region
If inspected, the vomit from a patient with congenital pyloric stenosis is noted as lacking what substance?
Bile
At about what age do infants with congenital pyloric stenosis typically start projectile vomiting?
2 weeks
What is the treatment for congenital pyloric stenosis?
Surgical incision (a pyloromyotomy)
What is the approximate incidence of congenital pyloric stenosis?
1:600 live births
Congenital pyloric stenosis often occurs in what demographic group?
Male first-born infants
Is the pancreas derived from the foregut, the midgut, or the hindgut?
The foregut
Is the head of the pancreas derived from the ventral or dorsal pancreatic bud?
The ventral pancreatic bud
Is the main duct of the pancreas derived from the ventral or dorsal pancreatic bud?
The ventral pancreatic bud
Is the body of the pancreas derived from the ventral or dorsal pancreatic bud?
The dorsal pancreatic bud
Is the tail of the pancreas derived from the ventral or dorsal pancreatic bud?
The dorsal pancreatic bud
Is the accessory pancreatic duct derived from the ventral or dorsal pancreatic bud?
The dorsal pancreatic bud
The head of the pancreas is derived from the _____ (ventral/dorsal) pancreatic bud, the body is derived from the _____ (ventral/dorsal) pancreatic bud, and the tail is derived from the _____ (ventral/dorsal) pancreatic bud.
Ventral; dorsal; dorsal
The main pancreatic duct is derived from the _____ (ventral/dorsal) pancreatic bud, whereas the accessory pancreatic duct is derived from the _____ (ventral/dorsal) pancreatic bud.
ventral; dorsal
True or False: The spleen arises as a diverticulum off of the gastrointestinal tract.
False; the spleen arises from the dorsal mesentery and is mesodermal
True or False: The spleen receives its blood supply from the foregut, although it is not derived from the foregut.
True; it is supplied via the celiac artery
A patient has a congenital malformation of the pancreas in which the ventral bud abnormally encircles the second part of the duodenum and forms a ring of tissue; what is the name of this abnormality?
Annular pancreas
An annular pancreas may lead to the narrowing of what structure?
The duodenum
What portion of the duodenum is affected by an annular pancreas?
The 2nd part of the duodenum
With regard to the embryologic development of the kidney, when does the pronephros develop?
During week 4
After week 4, what happens to the pronephros?
The pronephros degenerates
During which trimester of fetal development does the mesonephros arise?
During the first trimester
What fetal structure functions as the interim kidney for the first trimester?
Mesonephros
Of the following fetal structures, which ultimately contributes to the male genital system: the pronephros, mesonephros, or metanephros?
The mesonephros
The _____ develops into the bladder, urethra, and allantois.
urogenital sinus
The urogenital sinus develops into what three structures?
Bladder, urethra, and allantois
Which of the three fetal kidney structures develops into the adult kidney?
Metanephros
From what part of the developing kidney is the ureteric bud derived?
The mesonephros
What adult structures in the urinary tract are derived from the mesonephros?
The collecting ducts, calyces, pelves, and ureter
What adult structures in the urinary tract are derived from the metanephros?
The kidney from the glomerulus to the distal convoluted tubule
What syndrome results from bilateral renal agenesis?
Potter’s syndrome
In Potter’s syndrome, what pathophysiologic consequence of bilateral renal agenesis leads to the hallmark features of limb deformities, facial deformities, and pulmonary hypoplasia?
Oligohydramnios (remember: babies with Potter’s can’t Pee in utero)
What embryonic structure is malformed in patients with Potter’s syndrome?
The ureteric bud
What is the name of the anatomic abnormality resulting from the fusion of the inferior poles of the kidneys?
Horseshoe kidney
Horseshoe kidneys remain low in the abdomen because, during fetal development, they get trapped under the what artery?
The inferior mesenteric artery
Are horseshoe kidneys formed by the fusion of the two kidneys’ inferior or superior poles?
Inferior
During the embryologic development of the renal system, do the kidneys ascend or descend in the abdomen?
Ascend
True or False: A horseshoe kidney functions normally.
True
The mesonephric duct is also known as what?
The Wolffian duct
What four structures are derived from the mesonephric duct?
The Seminal vesicles, the Epididymis, the Ejaculatory duct, and the Ductus deferens (remember: SEED)
The paramesonephric duct is also known as what?
The müllerian duct
What three structures are derived from the paramesonephric duct?
The fallopian tubes, the uterus, and upper one-third of the vagina
What hormone inhibits the development of the paramesonephric duct in males?
Müllerian-inhibiting substance
What class of hormones promotes the development of the mesonephric ducts in males?
Androgens
Is male or female development the default fetal development?
Female; in the absence of a Y chromosome, female reproductive organs will develop
In female development, the _____ duct degenerates and the _____ duct develops.
mesonephric; paramesonephric
In male development, the _____ gene on the _____ chromosome codes for testis-determining factor.
SRY; Y
In male development, the mesonephric duct develops into all genitourinary internal structures except the _____.
Prostate
Which embryologic structure of the genitals degenerates in the female?
Mesonephric duct
Which cells produce the androgens that promote development of the mesonephric ducts?
Leydig cells
What structure becomes the lower two-thirds of the vagina?
The urogenital sinus
What is the name of the congenital pathology that is associated with incomplete fusion of the paramesonephric ducts?
Bicornuate uterus
What are 2 complications associated with a bicornuate uterus?
Bicornuate uterus is associated with urinary tract abnormalities and infertility
True or False: Bicornuate uterus results from incomplete fusion of the mesonephric ducts.
False; bicornuate uterus results from the incomplete fusion of the paramesonephric ducts
The genital tubercle forms what two structures under the influence of dihydrotestosterone?
The glans penis and the corpus spongiosum
The genital tubercle forms what two structures under the influence of estrogen?
The glans clitoris and the vestibular bulbs
The urogenital sinus forms what two structures under the influence of dihydrotestosterone in the male embryo?
The prostate and the bulbourethral glands
Embryologically, the urogenital sinus forms what two structures under the influence of estrogen in the female embryo?
The greater vestibular glands (of Bartholin) and the urethral and paraurethral glands (of Skene)
Embryologically, the urogenital folds develop into what structure under the influence of dihydrotestosterone in the male embryo?
The ventral shaft of the penis (penile urethra)
Embryologically, he urogenital folds develop into what structure under the influence of estrogen in the female embryo?
The labia minora
Embryologically, the labioscrotal swelling develops into what structure under the influence of dihydrotestosterone in the male embryo?
The scrotum
Embryologically, the labioscrotal swelling develops into what structure under the influence of estrogen in the female embryo?
The labia majora
Embryologically, the genital tubercle develops into what structure in the male and what structure in the female?
The glans penis in the male and the glans clitoris in the female
Embryologically, the urogenital folds develop into what structure in the male and what structure in the female?
The ventral shaft of the penis in the male and the labia minora in the female
Embryologically, the labioscrotal swellings develop into what structure in the male and what structure in the female
The scrotum in the male and the labia majora in the female
What condition results from an abnormal opening of the penile urethra on the inferior (ventral) side of the penis as a result of the failure of urethral folds to close?
Hypospadias (remember: Hypois below)
What condition results from an abnormal opening of the penile urethra on the superior (dorsal) side of the penis as a result of the faulty positioning of the genital tubercle?
Epispadias (remember: when you have Epispadias you hit your Eye when you pEE)
What common complication is prevented by fixing hypospadias?
UTI
Which is a more common congenital penile abnormality: epispadias or hypospadias?
Hypospadias
Which is associated with exstrophy of the bladder: epispadias or hypospadias?
Epispadias (remember: Exstrophy of the bladder is associated with Epispadias)
Which congenital penile abnormality is associated with failure of the urethral folds to close?
Hypospadias
Which congenital penile abnormality is associated with faulty positioning of the genital tubercle?
Epispadias
