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Anatomy and Embryology


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Implantation of blastocyst is present in which week?
The bilaminar disk is formed within which week?
Gastrulation, primitive streak, notochord, neural plate begin to form
Within week 3
Neural tube formed, organogenesis, extremely susceptible to teratogens
Weeks 3-8
Heart begins to beat, Upper and lower limb buds begin to form
Week 4
When do genitalia begin to have male/female characteristics?
Week 10
From day 0 to implantation at end of week 1, name stages of embryogenesis
From day 0 to implantation at end of week 1, name stages of embryogenesis
For next 9, name effect on fetus of following teratogens
ACE Inhibitors
Renal damage
Abnormal fetal development, fetal addiction
vaginal clear cell adenocarcinoma
congenital goiter or hypothyroidism
13-cis-retinoic acid
extremely high risk for birth defects
warfarin, x-rays
multiple anomalies
fetal infections
congenital malformations
how many umbilical arteries?
what kind of blood do the umbilical arteries carry?
deoxygenated blood from fetus
how many umbilical veins?
what kind of blood is carried by umbilical vein?
supplies oxygenated blood from placenta to the fetus
a single umbilical artery is associated with what anomalies?
congenital and chromosomal
What dervies from the following embyologic layers
Surface Ectoderm
adenohypophysis, lens of eye, epithelial linings, epidermis
neurohypophysis, CNS neurons, oligodendrocytes, astrocytes, pineal gland
neural crest
ANS, dorsal root ganglia, melanocytes, chromaffin cells of adrenal medulla, enterochromaffin cells, pia, celiac ganglion, Schwann cells, odontoblasts, parafollicular - C cells of thyroid, laryngeal cartilage
dura connective tissue, muscle, bone, cardiovascular structures, lymphatics, blood urogenital structures, serous linings of body cavities (peritoneal), spleen, adrenal cortex
gut tube epithelium and derivatives (lungs, liver, pancreas, thymus, thyroud, parathyroid)
what induces ectoderm to form neuroectoderm (neural plate)?
what is the postnatal derivative of the notochord?
nucleus pulposus of the intervertebral disk
Name the precursor for the ectoderm and its purpose
epiblast, invaginates to form primitive streak
Cells from the primitive streak give rise to
intraembryonic mesoderm and endoderm
How many germ layers in second week and what are they?
2, epiblast and hypoblast (remember rule of 2's for second week)
How many cavities in second week and what are they?
2, amniotic cavity and yolk sac (remember rule of 2's for second week)
How many components to placenta in second week and what are they?
2, cytotrophoblast and syncytiotrophoblast (remember rule of 2's for second week)
How many germ layers in third week and what are they?
3, (gastrula): ectoderm, mesoderm, endoderm (Rule of 3's for third week)
In the 3-8th weeks, fetal erythropoiesis occurs in
Yolk sac
In the 6-30th weeks, fetal erythropoiesis occurs in
In the 9-28th weeks, fetal erythropoiesis occurs in
Erythropoiesis occurs in the Bone marrow from the ---- week onward
Mnemonic for remembering fetal erythropoiesis?
Young Liver Synthesizes Blood
Embryonic structure gives rise to:

Truncus arteriosus
Ascending aorta and pulmonary trunk
Bulbus cordis
Smooth parts of left and right ventricle
Primitive ventricle
trabeculated parts of left and right ventricle
Primitive atria
trabeculated left and right atrium
Left horn of sinus venosus (SV)
coronary sinus
Right horn of sinus venosus (SV)
smooth part of right atrium
Right common cardinal vein and right anterior cardinal vein
Saturation level of blood in umbilical vein?
Foramen ovale: its function in fetal circulation?
Most oxygenated blood reaching the heart via the IVC is diverted through the foramen ovale and pumped out the aorta to the head.
Ductus Arteriosus: its function in fetal circulation?
Deoxygenated blood from the SVC is expelled into the pulmonary artery and ductus arteriosus to the lower body of the fetus.
What happens at birth, when infant takes a breath?
Decreased resistance in pulmonary vasculature causes increased left atrial pressure vs right atrial pressure; foramen ovale closes; increase in O2 leads to decrease in prostaglandins, causing closure of ductus arteriosus.
What drug can be given to close a patent ductus arteriosus?
What drug can be given to keep a patent ductus arteriosus open?
Fetal-postnatal derivatives
Umbilical vein becomes the:
ligamentum teres hepatis
umbilical arteries become the:
medial umbilical ligaments
ductus Arteriosus becomes the:
ligamentum arteriosum
ductus venosus becomes the:
ligamentum venosum
foramen ovale becomes the:
fossa ovalis
allantois - urachus becomes the:
median umbilical ligament
notochord becomes the:
nucleus pulposus
urachal cyst or sinus is a remnant of the:
allantois (urine drainage from the bladder)
Aortic Arch Derivatives
1st arch:
part of maxillary artery (1st is MAXimal)
2nd arch:
stapedial artery and hyoid artery (Second = Stapedial)
3rd arch:
common Carotid artery and proximal part of internal carotid artery (C is the 3rd letter of the alphabet)
4th arch:
on left, aortic arch; on right, proximal part of right subclavian artery 4th arch (4 limbs) = systemic
6th arch:
proximal part of pulmonary arteries and (on left only) ductus arteriosus. 6th arch = pulmonary and the pulmonary-to-systemic shunt (ductus arteriosus)
branchial clefts are dervied from:
branchial arched are derived from:
mesoderm and neural crests
branchial pouches are derived from:
mnemonic to remember branchial apparatus derivation:
CAP covers outside from inside (Clefts = ectoderm, Arches = mesoderm, Pouches = endoderm)
Branchial arch 1 derivatives
Meckel's cartilage:
Mandible, Malleus,incus,sphenoMandibular ligament
muscles of facial expression, Stapedius,Stylohyoid, posterior belly of digastric.
Branchial Arch 2 derivatives
Reichert's cartilage:
Stapes, Styloid process, lesser horn of hyoid, Stylohyoid ligament
Branchial arch 3 derivatives
greater horn of hyoid
stylopharyngeus (Think of pharnx: stylopharyngeus is innervated by glossopharyngeal nerve.
Branchial arch 4 to 6 derivatives
thyroid, cricoid, arytenoids, cornicuate, cuneiform
Muscles (4th arch):
mostly pharyngeal constrictors, cricothyroid, levator veli palatini.
5th arch:
makes no major developmental contributions
Muscles (6th arch):
all intrinsic muscles of larynx except cricothyroid
Nerve (6th arch):
CNX (recurrent laryngeal branch)
Branchial arch innervation
Arch 1 derviatives are supplied by:
CN V2 and V3
Arch 2 derivatives are supplied by:
Arch 3 derivatives are supplied by:
Arch 4 and 6 derivatives supplied by:
Branchial cleft derivatives
1st cleft develops into
external auditory meatus
2nd through 4th clefts form:
temporary cervical sinuses, which are obliterated by proliferation of 2nd arch mesenchyme.
Persistent cervial sinus can lead to a:
branchial cyst in the neck
Ear development:
Bone: Incus/Malleus come from:
1st arch
Bone: Stapes comes from:
2nd arch
Muscle: Tensor tympani (V3) comes from:
1st arch
Muscle: Stapedius (VII) comes from:
2nd arch
External auditory meatus comes from:
1st cleft
Eardrum, eustacian tube comes from:
1st pharyngeal membrane
Branchial pouch derviatives:
1st pouch develops into:
middle ear cavity, eustacian tube, mastiod air cells (1st pouch contributes to endoderm-lined structures of ear)
2nd pouch develops into:
epithelial lining of palatine tonsil
3rd pouch (dorsal wings) develops into:
inferior parathyroids (3rd pouch contributes to 3 structures: thymus, left and right inferior parathyroids)
3rd pouch (ventral wings) develops into:
4th pouch develops into:
superior parathyroids
Aberrant development of 3rd and 4th pouches -->
DiGeorge's syndrome --> leads to T-cell deficiency (thymic hypoplasia) and hypocalcemia (parathyroid glands)
Site of:
T-cell maturation
Encapsulated or unencapsulated?
which branchial pouch?
from epithelium of 3rd branchial pouches
Lymphocyte origin?
lymphocytes are of mesenchymal origin
cortex is dense with:
immature T cells
medulla is pale with:
mature T cells and epithelial reticular cells and contains Hassall's corpuscles. (think of the Thymus as "finishing school" for T cells. They arrive immature and "dense" in the cortex; they are mature in the medulla.
What occurs at the corticomedullary junction?
Positive and negative selection
Thyroid diverticulum arises from:
floor of primitive pharnyx, descends into neck.
Connected to tongue by
thyroglossal duct, which normally disappears but may persist as a pyramidal lobe of thyroid.
Formen cecum is:
a normal remnant of the thyroglossal duct
The most common ectopic thyroid tissue site is the:
Tongue development
1st branchial arch forms the
anterior 2/3 of the tongue (thus sensation via CN V3, taste via CNVII)
3rd and 4th branchial arches form:
posterior 1/3 of the tongue (thus sensation and taste mainly via CN IX, extreme posterior via CN X).
Cranial nerves for taste?
CN VII, IX, X (solitary nucleus)
Motor innervation is via CN?
define cleft lip
failure of fusion of the maxillary and medial nasal processes
define cleft palate
failure of fusion of the lateral palatine processes, the nasal septum, and/or the median palatine process.
diaphragm is derived from:
Septum transversarium, Pleuroperitoneal folds, Body wall, Dorsal mesentery of esophagus (Several Parts Build Diaphragm. Diaphragm descends during develpoement but maintains innervation from above C3-C5. "C3, 4, 5 keeps the diaphragm alive."
What is a hiatial hernia
abdominal contents may herniate into the throax due to incomplete development of the diaphragm.
What is Intramembranous bone formation
spontaneous bone formation without preexisting cartilage.
What is Endochondral bone formation
ossification of carilaginous molds. Long bones form by this type of ossification at 1o and 2o centers
What is Meckel's diverticulum
persistence of the vitelline duct or yolk stalk. May contain ectopic acid-secreting gastric muscosa and/or pancreatic tissue.
What is the most common congenital anomaly of the GI tract?
Meckel's diverticulum
Complications of Meckel's Diverticulum?
can cause bleeding or obstruction near the terminal ileum.
Comparison of Meckel's Diverticulum to Omphalomesenteric cyst?
Cystic dilatation of the vitelline duct.
It is Associated with
intussusception and volvulus
Mnemonic to remember Meckel's diverticulum
The five 2's: 2 inches long, 2 feet from the ileocecal valve, 2% of population, commonly presents in first 2 years of life, may have 2 epithelia.
Parcreas is derived from the
ventral pancreatic bud becomes the
pancretic head, uncinate process (lower half of head), and main pancreatic duct.
dorsal pancreatic bud becomes:
everything else (body, tail, isthmus, and accessory pancreatic duct).
Spleen arises from
dorsal mesentery but is supplied by artery of foregut.
Mesonephric (wolffian) duct develops into
Develops into Seminal vesicles, Epididymis, Ejaculatory duct, and Ductus deferens (SEED)
Paramesonephric (mullerian) duct
develops into
Develops into fallopian tube, uterus, and part of vagina.
Mullerian inhibiting substance is secreted by:
the testes to suppress development of paramesonephric ducts in males.
Bicornuate uterus:
results from and is Associated with
incomplete fusion of the paramesonephric ducts.
urinary tract abnormalities and infertility
Genital tubercle (male) -->
glans penis via dihydrotestosterone
genital tubercle (female) -->
glans clitoris via estrogen
urogenital sinus (male) -->
corpus spongiosum, bulbourethral glands (of Cowper), prostate gland: via dihydrotestosterone
urogenital sinus (female) -->
vestiubular bulbs, greater vestibular glands (of Bartholin), Urethral and paraurethral glands (of Skene): via estrogen
urogenital folds (male) -->
ventral shaft of penis (penile urethra) via dihydrotestosterone
urogenital folds (female) -->
labia minora via estrogen
labioscrotal swelling (male) -->
scrotum via dihydrotestosterone
labioscrotal swelling (female) -->
labia majora via estrogen
Congenital penile abnormalities
abnormal opening of the penile urethra on inferior (ventral) side of penis due to failure of urethral folds to close.
abnormal opening of the penile urethra on superior (dorsal) side of penis due to faulty positioning of the genital tubercle.
epispadia is associated with
exstrophy of the bladder
Which is more common, hypospadia or epispadia?
Hypospadial; fix hypospadias to prevent UTI's
Derivation of sperm parts:
acrosome is derived from
the golgi apparatus and flagellum (tail) from one of the centrioles.
what does the neck of the sperm have?
Middle piece (neck) has Mitochondria.
Sperm food supply is:
Primary oocytes begin and complete meiosis I when?
begin: during fetal life; complete: just prior to ovulation. Meiosis I is arrested in prOphase for years until Ovulation.
What phase is Meiosis II arrested in?
Meiosis II is arrested in METaphase until fertilization. -- "An egg MET a sperm."
What is polyhydramnios?
high amount of amniotic fluid (>1.5-2L)
What is polyhydramnios clinically associated with?
esophageal/duodenal atresis and anencephaly both of which impair the ability of the fetus to swallow amniotic fluid
What is the condition leading to low amniotic fluid (<0.5L) called?
What 2 conditions is oligohydramnios associated with?
Bilateral renel agenesis or posterior urethral valves (in males) which results in the failure of the fetus to excrete urine into the amniotic fluid.
What syndrome can oligohydramnios result in?
Potter's Syndrome
What does the term Potter's syndrom describe?
Bilateral renal agenesis leading to oligohydramnios which results in fetal limb and facial deformaties and pulmonary hypoplasis
What causes Potter's syndrome?
Malformation of the ureteric bud
What results when the poles of both kidneys fuse during development?
Horseshoe kidney
What arrests the ascend of the fused kidneys?
The horseshoe kidneys get trapped under the inferior mesenteric artery.
Which muscles form the rotator cuff?
Supraspinatus, Infraspinatus, Teres minor, and Subscapularis (SItS)
Which muscle helps the deltoid abduct the arm?
What function does the Infraspinatus muscle have?
laterally rotates the arm at the shoulder joint
What is the function of the Teres minor muscle?
to adduct and laterally rotate the arm (Possible mistake in First Aid)
Which muscle medically rotates and adducts the arm?
Name the thenar muscles.
Opponens pollicis, Abductor pollicis brevis, Flexor pollicic brevis
Name the hypothenar muscles.
Opponens digiti minimi, Abductor digiti minimi, Flexor digiti minimi
What functions do the thenar and hypothenar muscles preform?
oppose, abduct and flex (OAF)
What structures can be injured when a football player's cleated shoe is planted firmly in the turf and the knee is struck from the lateral side?
medial collateral ligament (MCL), medial meniscus, and anterior cruciate ligament (ACL) (unhappy triad on the knee joint)
What does a anterior drawer sign indicate?
Tearing of the Anterior cruciate ligament (ACL)
What does abnormal passive abduction indicate?
A torn Medial collateral ligament (MCL)
The recurrent laryngeal nerve is a branch of which cranial nerve?
Which muscles does it supply?
intrinsic muscles of the larynx except the cricothyroid muscle
What structure does the right recurrent laryngeal nerve wrap around?
right subclavian artery
What structure does the left recurrent laryngeal nerve wrap around?
arch of the aorta and the ligamentum arteriosum
In what kind of surgery can this nerve be damaged in?
thyroid surgery
What happens when this nerve gets damaged?
Name the layers of the scalp
skin, connective tissue, aponeurosis, loose connective tissue, pericranium (SCALP)
Name the meninges.
Dura, arachnoid, and pia (DAP)
What space is found between the dura and arachnoid?
subdural space
Between what meninges is the subarachnoid space located?
between the arachnoid and the pia
What is found in the subarachnoid space?
In which scalp layer are the emissary veins found?
loose connective tissue
List the structures found in the carotid sheath (in the order from lateral, medial, posterior)
Internal jugular vein, common carotid artery, and vagus nerve (VAN)
What structure crosses the diaphragm at T8?
IVC (I 8 10 EGG's AT 12)
At what T level does the esophagus and vagus nerve cross the diaphragm?
T10 (I 8 10 EGG's AT 12)
What structure crosses the diaphragm at T12?
aorta, thoracic duct, and azygous vein (I 8 10 EGG's AT 12)
Name the innervation of the diaphragm
C3, 4, and 5 (phrenic nerve)
Where can the pain from the diaphragm be reffered to?
What artery supplies the SA and AV nodes?
RCA right coronary artery
The inferior portion of the left ventricle is supplied by what artery 80% of the time?
RCA via the PD posterior descending artery
In which artery does coronary artery occlusion most sommonly occur?
LAD left anterior descending artery
What artery supplies the anterior interventricular septum?
LAD left anterior descending artery
When do coronary arteries fill?
during diastole
What is the most posterior part of the heart?
left atrium
What can the enlargement of the left atrium cause?
What does each bronchopulmonary segment contain?
3º (segmental) bronchus and 2 arteries (bronchial and pulmonary) in the center
What drains along the borders of the bronchopulmonary segments?
veins and lymphatics
What runs with the airways?
How many lobes does the right lung has?
3 lobes
Which lung lobe has 2 lobes?
What is the homologue of the right middle lobe in the left lobe?
Which lung is the more common site for inhaled foregin body?
right lung?
Why is 1 lung a more common site for inhaled foregin body?
Because of the lessvacute angle of the right main stem bronchus
What is the relation of the pulmonary artery to the bronchus in each lung hilus?
RALS - right lung anterior and left lung superior
What does the femoral sheath contain?
femoral artery, femoral vein, and femoral canal (containing deep inguinal lymph node)
Does the femoral nerve lie within the femoral sheath?
no, it lies outside the sheath
What do you call the entrance of abdominal contents through the femoral canal?
femoral hernia
What does the femoral triangle contain?
femoral vein, aretery and nerve (VAN)
Where does the femoral hernia protrude to?
below and lateral to the pubic tubercle
What are abdominal hernias?
protrusions of peritoneum through an opening - usually sites of weakness
What is the name of the hernia in which abdominal structures enter the thorax?
diaphragmatic hernia
What is the most common diaphragmatic hernia?
hiatal hernia
What happens in this type of hernia?
the stomach herniates upward through the esophageal hiatus
What can result from a defective development of pleuroperitoneal membrane in infants?
diaphragmatic hernias
From where does a direct hernia protrude?
from the inguinal (Hesselbach's) triangle - bulges directly through the abdominal wall medial to the inferior epigastric artery
Which inguinal ring does it go through?
external inguinal ring only
Who usually gets a direct hernia?
older men
What does the indirect hernia go through?
the internal (deep) inguinal ring and external (superficial) inguinal ring and into the scrotum
On which side of the inferior epigastric artery does the indirect hernia enter the internal inguinal ring?
lateral to the inferior epigastric artery
Who usually get an indirect hernia and why?
infants, because of the failure of processus vaginalis to close
Which structures make up Hesselbach's triangle?
inferior epigastric artery, lateral border of rectus abdominis, and inguinal ligament
Where does the inguinal canal start and end?
begins at the deep inguinal ring and terminates at the superficial ring
What does the inguinal canal transmit?
the spermatic cord or the round ligament of the uterus and the genital branch of the genitofemoral nerve
What structures make up the anterior wall of the inguinal canal?
aponeuroses of the external oblique and internal oblique muscles
What structures make up the posterior wall of the inguinal canal?
aponeurosis of the transverse abdominal muscle and transversalis fascia
What structures make up the superior wall of the inguinal canal?
arching fibers of the internal oblique and transverse muscles
What structures make up the inferior wall (floor) of the inguinal canal?
inguinal and lacunar ligaments
From where does the stomach receive its main blood supply?
from the branches of the celiac trunk
From where does the celiac trunk arise?
from the front of the abdominal artery immediately below the aortic hiatus of the diaphragm
What arteries does the celiac trunk divide into?
left gastric, splenic, and common hepatic arteries
What does the left gastric artery run along?
lesser curvature of the stomach
What artery does the left gastric artery anastomose with?
the right gastric artery
What does the splenic artery run along?
runs along the superior boarder of the pancrease
What arteries does the splenic artery give rise to?
(dorsal pancreatic artery), short gastric arteries and left gastroepiploic artery
What does the left gastroepiploic artery run along?
the greater curvature of the stomach
What does the common hepatic artery divide into?
hepatic artery proper, right gastric artery, and gastroduodenal artery
esophageal varices results at the anastamosis of which veins?
left gastric vein (portal) and azygous (systemic)
manifestation of portal hypertension at the anastamosis of the superior rectal with the middle/inferior rectal veins
caput medusae is at anastamosis of which veins
paraumbilical (portal) and inferior epigastric (systemic)
the two other sites of portal system anastamosis
retroperitoneal vein (portal) with renal vein (systemic) and retroperitoneal vein with paravertebral vein (systemic)
3 manifestations seen in alcoholic cirrhosis
esoph. Varices, hemorrhoids, caput medusae "Gut, butt and caput"
What drains the lymph from right arm and right half of head
right lymphatic duct
What does the Thoracic duct drain
everything that right lymphatic duct does not
location of pectinate line
where hindgut meets ectoderm
innervation, hemorrhoid type, aterial supply and venous drainage above pectinate line
visceral innervation(not painful), internal hemorrhoids (think of adenocarcinoma association), superior rectal artery(branch of IMA), and superior rectal vein to inferior mesenteric vein to portal system
innervation, hemorrhoid type, aterial supply and venous drainage below pectinate line
somatic innervation(painful!), external hemorrhoids (think of squamous cell carcinoma association), inferior rectal artery, inferior rectal vein to internal pudendal vein to internal iliac vein to IVC
parts of duodenum that are retroperitoneal
2nd, 3rd and 4th parts

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