Embryology - Part 2 Flashcards
Embryologically, the left sixth aortic arch gives rise to which two structures (C)?
Proximal pulmonary arteries and ductus arteriosus
During fetal erythropoiesis, when does the yolk sac produce fetal RBCs?
Weeks 3-8
During fetal erythropoiesis, when does the liver produce fetal RBCs?
Weeks 6-30
During fetal erythropoiesis, when does the spleen produce fetal RBCs?
Weeks 9-28
During fetal erythropoiesis, when does the bone marrow start producing fetal RBCs?
Week 28
During fetal erythropoiesis, what is the first location to produce fetal RBCs during development?
The yolk sac
Fetal erythropoiesis occurs in what organs during development?
The yolk sac, the liver, the spleen, and the bone marrow
What is the order in which organs become the primary site of fetal erythropoiesis?
The Yolk sac, Liver, Spleen, Bone marrow
remember: Young Liver Synthesizes Blood
What is the composition of fetal hemoglobin?
α2γ2
What is the composition of adult hemoglobin?
α2β2
Fetal hemoglobin and adult hemoglobin share the same ____ chains. However, they differ in that fetal hemoglobin contains ____ chains, whereas adult hemoglobin contains ____ chains.
α; γ; β
What is the approximate oxygen saturation in the umbilical vein?
0.8
Name the three important shunts in the fetal circulation.
Foramen ovale, ductus arteriosus, and ductus venosus
What structure shunts blood from the right atrium to the left atrium in the fetal circulation?
The foramen ovale
What structure shunts blood from the pulmonary artery to the aorta in the fetal circulation?
The ductus arteriosus
What structure connects the umbilical vein with the inferior vena cava in the fetal circulation?
The ductus venosus
Well-oxygenated blood from the inferior vena cava mainly passes through which shunt to reach the brain of the fetus?
The foramen ovale
Less-oxygenated blood from the superior vena cava mainly passes through which shunt to reach the lower limbs of the fetus?
The ductus arteriosus
The _____ shunts well-oxygenated blood from the placenta to the IVC to bypass the _____ in the fetus.
ductus venosus; liver
During fetal life, is the pressure in the right atrium or the left atrium higher?
The right atrium
At birth, after the neonate takes a breath, is the pressure in the right atrium or the left atrium higher?
The left atrium
With an infant’s first breath, the resistance in the pulmonary vasculature _____ (increases/decreases), which causes ______ (increased/decreased) left atrial pressure as compared with the right side. This change in the pressure gradient causes the closure of the ______.
decreases; increased; foramen ovale
After a neonate has started breathing, the oxygen saturation in the blood ______ (increases/decreases), thereby leading to a(n) ______ (increase/decrease) in the synthesis of prostaglandins, which is responsible for the closure of the ______.
Increases; decrease; ductus arteriosus
The _____ closes in response to alterations in the pressure gradient across the atria, whereas the _____ closes in response to decreased prostaglandin synthesis.
foramen ovale; ductus arteriosus
What is the drug of choice to constrict the ductus arteriosus in an infant with patent ductus arteriosus?
Indomethacin
Certain drugs can be given to the newborn that affect the patency of the ductus arteriosus. The drug ______ can close the ductus arteriosus. By contrast, ______ can keep the ductus arteriosus open.
Indomethacin; prostaglandins
The umbilical vein in the fetus becomes what structure in the adult?
The ligamentum teres hepatis
The ligamentum teres hepatis is contained in what structure in the adult?
The falciform ligament
The umbilical arteries in the fetus become what structures in the adult?
The mediaL umbilical ligaments come from the umbiLical arteries
The ductus arteriosus in the fetus becomes what structure in the adult?
The ligamentum arteriosum
The ductus venosus in the fetus becomes what structure in the adult?
The ligamentum venosum
The foramen ovale in the fetus becomes what structure in the adult?
The fossa ovalis
The allantois (urachus) in the fetus becomes what structure in the adult?
The mediaN umbilical ligament comes from the allaNtois
The notochord in the fetus becomes what structure in the adult?
The nucleus pulposus of the intervertebral disks
The ligamentum teres hepatis is a remnant of what structure in the fetus?
The umbilical vein
The medial umbilical ligaments are remnants of what structures in the fetus?
The umbilical arteries
The ligamentum arteriosum is a remnant of what structure in the fetus?
The ductus arteriosus
The ligamentum venosum is a remnant of what structure in the fetus?
The ductus venosus
The fossa ovalis is a remnant of what structure in the fetus?
The foramen ovale
The median umbilical ligament is a remnant of what structure in the fetus?
The allantois (urachus)
The nucleus pulposus found in intervertebral disks is derived from what fetal structure?
The notochord
The medial umbilical ligament is derived from the _____, whereas the median umbilical ligament is derived from the _____.
umbilical artery; allantois (urachus)
A urachal cyst or sinus is a remnant of what structure?
The urachus
What is the name for the part of the allantoic duct that runs between the bladder and umbilicus?
The urachus
The urachus connects the _____ to the ______.
Bladder; umbilicus
Embryologically, the first aortic arch gives rise to part of what artery?
The MAXillary artery
remember: the 1st arch is MAXimal
Embryologically, the second aortic arch gives rise to what two arteries?
The stapedial artery and the hyoid artery (remember: Second = Stapedial)
Embryologically, the third aortic arch gives rise to which two arteries?
The common Carotid and proximal internal Carotid (remember: C is the third letter of the alphabet)
Embryologically, the fourth aortic arch on the left gives rise to what structure?
The aortic arch (remember: 4th arch [4 limbs] = systemic circulation)
Embryologically, the fourth aortic arch on the right gives rise to what structure?
The subclavian artery (remember: 4th arch [4 limbs] = systemic circulation)
Embryologically, what does the fifth aortic arch give rise to?
Nothing
Embryologically, the sixth aortic arch gives rise to part of what structure on both the right and the left?
The pulmonary artery
Embryologically, the sixth aortic arch gives rise to part of the pulmonary artery, as well as what structure on the left side?
The ductus arteriosus
Embryologically, the fourth aortic arch gives rise to the _____ on the left and the _____ on the right.
Aortic arch; subclavian artery
What are the adult derivatives of the telencephalon in the developing brain?
The cerebral hemispheres and lateral ventricles
What are the adult derivatives of the diencephalon in the developing brain?
The thalami and third ventricle
What is the adult derivative of the mesencephalon in the developing brain?
Midbrain
What are the adult derivatives of the metencephalon in the developing brain?
The pons and the cerebellum
What is the adult derivative of the myelencephalon in the developing brain?
The medulla
What adult structure is derived from the cavity in the embryonic mesencephalon?
The aqueduct
What adult structure is derived from the cavity in the embryonic metencephalon and myelencephalon?
4th ventricle
Neural tube defects are associated with low intake of what substance during pregnancy?
Folic acid
Neural tube defects are associated with elevated levels of what substance in amniotic fluid and maternal serum?
α-Fetoprotein
In the fetus, the failure of the bony spinal canal to close (without structural herniation) will result in what type of neural tube defect?
Spina bifida occulta
A _____ is characterized by the meninges herniating through a spinal canal defect.
Meningocele
A _____ is characterized by the meninges and spinal cord herniating though a spinal canal defect.
myelomeningocele
Identify the three types of spinal neural tube defects.
Spina bifida occulta, meningocele, and myelomeningocele
What is the most common location of spina bifida occulta?
Lower vertebral levels
True or False: In spina bifida occulta, the dura mater is malformed.
False; the dura is intact
What is the term for a malformation of the anterior neural tube, causing no brain or calvarium?
Anencephaly
Anencephaly is characterized by malformation of the _____ (anterior/posterior) end of the neural tube.
Anterior
In anencephaly, the α-fetoprotein level is typically _____ (decreased/increased).
Increased
What happens to the amniotic fluid if the fetus has anencephaly?
There is polyhydramnios due to the lack of a swallowing center in the brain: the fetus cannot swallow amniotic fluid
What is the term for decreased separation of the cerebral hemispheres across the midline in a fetus?
Holoprosencephaly
An infant has cyclopia; what neural defect are you worried about?
Holoprosencephaly
Name 2 syndromes associated with holoprosencephaly.
Patau’s syndrome and severe fetal alcohol syndrome
Chiari type II malformation is associated with what type of herniation?
Cerebellar tonsillar herniation
What CSF abnormality results when the cerebellar tonsils herniate through the foramen magnum in a Chiari II malformation?
Aqueductal stenosis and hydrocephaly
A patient presents with syringomyelia, throacolumbar myelomeningocele and hydrocephalus; what syndrome do you suspect?
A Chiari type II malformation
What type of posterior fossa malformation is associated with a large posterior fossa and an absent cerebellum with a cyst in its place?
Dandy-Walker
True or False: A Dandy-Walker malformation is a posterior fossa malformation associated with a large cyst compressing the cerebellum against the bones of the posterior fossa.
False; in a Dandy-Walker malformation, the cerebellum is absent and the space is filled by a cyst
An MRI of the cervical spine shows an enlargement of the central canal of the spinal cord; what is the term for this lesion?
Syringomyelia; syrinx is greek for tube, as in syringe
A patient has syringomyelia; which neuronal fibers in the spinal cord are damaged?
Crossing fibers of the spinothalamic tract are damaged by the expanding central canal
You are seeing a patient who has a loss of pain and temperature sensation in the hands, but touch is intact; where is the lesion?
This describes the “cape-like” distribution of syringomyelia; this is most commonly at C8-T1
What malformation of the calvarium is commonly associated with syringomyelia?
Chiari II malformation
True or False: Syringomyelia typically presents with unilateral loss of pain and temperature sensation.
False; this is a midline lesion causing bilateral pain and temperature loss with preservation of touch sensation
Embryologically, what are the three components of the branchial apparatus (also called the pharyngeal apparatus)?
Clefts, arches, and pouches
Embryologically, branchial clefts are derived from what primary germ layer?
The ectoderm
Embryologically, branchial arches are derived from what primary germ layer and what cell type?
The mesoderm and the neural crest
Which components of the branchial arch are derived from mesoderm?
Muscles and arteries
Which components of the branchial arch are derived from neural crest cells?
Bones and cartilage
Embryologically, branchial pouches are derived from what primary germ layer?
The endoderm
What is the other name for the branchial apparatus in a developing embryo?
The pharyngeal apparatus
What is the other name for branchial clefts in a developing embryo?
Grooves
What is the order of branchial apparatus components, from outside to inside?
Clefts, Arches, Pouches (remember: CAP covers outside from inside)
Embryologically, branchial arch 1 derivatives are supplied by which two cranial nerves?
V2 and V3
Embryologically, cranial nerves V2and V3 supply the derivatives of which branchial arch?
Branchial arch 1
Branchial arch 2 derivatives are supplied by which cranial nerve?
VII
Embryologically, cranial nerve VII supplies the derivatives of which branchial arch?
Branchial arch 2
Branchial arch 3 derivatives are supplied by which cranial nerve?
IX
Embryologically, cranial nerve IX supplies the derivatives of which branchial arch?
Branchial arch 3
Embryologically, branchial arches 4 and 6 derivatives are supplied by which cranial nerve?
X
Embryologically, cranial nerve X supplies the derivatives of which branchial arches?
Branchial arches 4 and 6
Branchial arch 1 is the origin of muscles involved in what action?
Chewing
Branchial arch 2 is the origin of muscles that perform which actions?
Facial expressions
Branchial arch 4 is the origin for muscles that perform which action? Arch 6?
Swallowing; speaking
Which four cranial nerves are the only ones with both sensory and motor components?
V3, VII, IX, and X
Embryologically, the mandible is derived from which branchial arch?
Branchial arch 1
Embryologically, the malleus is derived from which branchial arch?
Branchial arch 1
Embryologically, the incus is derived from which branchial arch?
Branchial arch 1
Embryologically, the sphenomandibular ligament is derived from which branchial arch?
Branchial arch 1
Embryologically, the muscles of mastication (the temporalis, the masseter, and the medial and lateral pterygoids) are derived from which branchial arch?
Branchial arch 1
Embryologically, the mylohyoid is derived from which branchial arch?
Branchial arch 1
Embryologically, the anterior belly of the digastric muscle is derived from which branchial arch?
Branchial arch 1
Embryologically, the tensor tympani is derived from which branchial arch?
Branchial arch 1
Embryologically, the tensor veli palatini is derived from which branchial arch?
Branchial arch 1
Embryologically, the anterior two thirds of the tongue are derived from which branchial arch?
Branchial arch 1
Embryologically, the cartilaginous derivatives of branchial arch 1 in the embryo are called what?
Meckel’s cartilage
What syndrome occurs when neural crest cells in the first branchial arch fail to migrate, causing mandibular hypoplasia and facial abnormalities?
Treacher Collins syndrome
Embryologically, branchial arch 1 gives rise to which two cranial nerves?
V2 and V3
Which bones are derived from the first branchial arch?
The mandible, malleus and incus (Meckel’s cartilage)
Which muscles are derived from the first branchial arch?
The Muscles of Mastication (temporalis, Masseter, lateral and Medial pterygoids), Mylohyoid, anterior belly of digastric, tensor tympani, tensor veli palatini, anterior 2/3 of tongue
Which ligament is derived from the first branchial arch?
The sphenoMandibular ligament (Meckel’s cartilage)
Embryologically, the cartilaginous derivatives from branchial arch 2 are called what?
Reichert’s cartilage
Embryologically, the stapes is derived from which branchial arch?
Branchial arch 2
Embryologically, the styloid process is derived from which branchial arch?
Branchial arch 2
Embryologically, the lesser horn of the hyoid is derived from which branchial arch?
Branchial arch 2
Embryologically, the stylohyoid ligament is derived from which branchial arch?
Branchial arch 2
Embryologically, the muscles of facial expression are derived from which branchial arch?
Branchial arch 2
Embryologically, the stapedius is derived from which branchial arch?
Branchial arch 2
In the embryo, the posterior belly of the digastric muscle is derived from which branchial arch?
Branchial arch 2
Embryologically, the stylohyoid is derived from which branchial arch?
Branchial arch 2
Which bones are derived from the second branchial arch?
The Stapes, Styloid process, and lesser horn of hyoid (Second branchial arch)
Which muscles are derived from the second branchial arch?
The muscles of facial expression, Stapedius, Stylohyoid, and posterior belly of the digastric (Second branchial arch)
Which ligament is derived from the second branchial arch?
The Stylohyoid ligament (Second branchial arch)
Embryologically, branchial arch 2 gives rise to which cranial nerve?
VII
Embryologically, the malleus is derived from branchial arch _____, the incus is derived from branchial arch _____, and the stapes is derived from branchial arch _____.
1; 1; 2
Embryologically, the stylohyoid ligament is derived from branchial arch _____, whereas the sphenomandibular ligament is derived from branchial arch _____.
2; 1
Embryologically, the greater horn of the hyoid is derived from which branchial arch?
Branchial arch 3
Embryologically, the stylopharyngeus muscle is derived from which branchial arch?
Branchial arch 3 (think of pharynx: stylopharyngeus innervated by glossopharyngeal nerve)
Embryologically, branchial arch 3 gives rise to which cranial nerve?
IX (think of pharynx: stylopharyngeusinnervated by glossopharyngeal nerve)
Embryologically, the greater horn of the hyoid is derived from branchial arch _____, and the lesser horn of the hyoid is derived from branchial arch _____.
3; 2
Embryologically, the stylohyoid muscle is derived from branchial arch ____, whereas the stylopharyngeus muscle is derived from branchial arch ____.
2; 3
What is the embryonic origin of a congenital pharyngocutaneous fistula?
This is the persistence of a cleft and pouch creating a fistula between the tonsillar area and a cleft in the lateral neck
Embryologically, thyroid cartilage is derived from which branchial arches?
Branchial arches 4 and 6
Embryologically, cricoid cartilage is derived from which branchial arches?
Branchial arches 4 and 6
Embryologically, the arytenoids are derived from which branchial arches?
Branchial arches 4 and 6
Embryologically, the corniculate and cuneiform cartilages are derived from which branchial arches?
Branchial arches 4 and 6
Which cartilages are derived from the fourth and sixth branchial arches?
Thyroid, cricoid, arytenoid, corniculate, and cuneiform cartilage
Embryologically, most pharyngeal constrictor muscles are derived from what branchial arch?
Branchial arch 4
Embryologically, the cricothyroid muscle is derived from what branchial arch?
Branchial arch 4
Embryologically, the levator veli palatini is derived from what branchial arch?
Branchial arch 4
Which muscles are derived from the fourth branchial arch?
Most pharyngeal constrictors, the cricothyroid, and the levator veli palatini
Embryologically, all intrinsic muscles of the larynx (except the cricothyroid) are derived from what branchial arch?
Branchial arch 6
Which muscles are derived from the sixth branchial arch?
All intrinsic muscles of the larynx except the cricothyroid
Embryologically, branchial arch 4 gives rise to which laryngeal branch of which cranial nerve?
The superior laryngeal branch of cranial nerve X; this is responsible for swallowing
Embryologically, branchial arch 6 gives rise to which branch of cranial nerve X?
The recurrent laryngeal branch of cranial nerve X; this is responsible for speaking
Embryologically, most intrinsic muscles of the larynx are derived from branchial arch _____, except for the cricothyroid, which is derived from branchial arch _____.
6; 4
Embryologically, the levator veli palatini is derived from branchial arch _____, whereas the tensor veli palatini is derived from branchial arch _____.
4; 1
Embryologically, the superior laryngeal nerve is derived from branchial arch _____, whereas the recurrent laryngeal branch is derived from branchial arch _____.
4; 6
Embryologically, the posterior third of the tongue is derived from which branchial arches?
Branchial arches 3 and 4
True or False: Embryologically, branchial arch 5 makes no major contribution to any structure.
True
Embryologically, the anterior two thirds of the tongue are derived from branchial arch _____, whereas the posterior third is derived from branchial arches _____ and _____.
1; 3; 4
What structure is derived from the first branchial cleft?
The external auditory meatus
The external auditory meatus is derived from what branchial structure?
The first branchial cleft
Branchial clefts 2 through 4 develop into ______ ______, which are temporary.
Cervical sinuses
True or False: Derivatives of the second through fourth branchial clefts are present in the adult.
False; the cervical sinuses formed from branchial clefts 2 through 4 are temporary
On imaging, where would you expect to find a persistent cervical sinus?
On the lateral aspect of the neck, as this arises from a branchial cleft cyst
Embryologically, the middle ear cavity is derived from which branchial pouch?
Branchial pouch 1
Embryologically, the Eustachian tube is derived from which branchial pouch?
Branchial pouch 1
Embryologically, the mastoid air cells are derived from which branchial pouch?
Branchial pouch 1
What are the derivatives of the first branchial pouch?
The middle ear cavity, eustacian tube, and mastoid air cells
Embryologically, the first branchial pouch contributes to structures that are lined by which germ cell layer?
The endoderm
Embryologically, the epithelial lining of the palatine tonsils are derived from which branchial pouch?
Branchial pouch 2
What are the derivatives of the second branchial pouch?
The epithelial lining of the palatine tonsils
Embryologically, the inferior parathyroid glands are derived from which branchial pouch?
The dorsal wings of branchial pouch 3 (remember: 3rd pouch structures end up below 4th pouch structures)
Embryologically, the thymus is derived from which branchial pouch?
The ventral wings of branchial pouch 3 (remember: 3rd pouch structures end up below 4th pouch structures)
Embryologically, the superior parathyroid glands are derived from which branchial pouch?
The dorsal wings of branchial pouch 4 (remember: 3rd pouch structures end up below 4th pouch structures)
Embryologically, the superior parathyroid glands are derived from branchial pouch _____, and the inferior parathyroid glands are derived from branchial pouch _____.
4; 3
Embryologically, which three structures are derived from the third branchial pouch?
The thymus and the right and left inferior parathyroid glands
Embryologically, aberrant development of branchial pouches 3 and 4 leads to what syndrome?
DiGeorge Syndrome
The muscles of facial expression are derived from branchial arch _____, whereas the muscles of mastication are derived from branchial arch _____.
2 ; 1
Embryologically, the anterior belly of the digastric is derived from branchial arch ____, and the posterior belly of the digastric muscle is derived from branchial arch ____.
1 ; 2
Embryologically, the stapedius is derived from branchial arch ____, and the tensor tympani is derived from branchial arch ____.
2 ; 1
Embryologically, DiGeorge syndrome involves aberrant fetal development of the ______, which leads to T-lymphocyte deficiency, and of the ______ _____, which leads to hypocalcemia.
Thymus; parathyroid glands
