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Foundations > Embryology- GI/Pelvis/Perineum > Flashcards

Embryology- GI/Pelvis/Perineum Flashcards

1
Q

What is the original structure that forms the GI tract?

A

Yolk sac

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2
Q

What do the umbilical arteries become in adults?

A

Medial umbilical ligaments

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3
Q

What does the urachus become in adults?

A

Median umbilical ligament

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4
Q

What is the urachus?

A

Fetal structure that drains urine from fetus to the amnionic sac
- It is the distal portion of allantois that forms later on, remains as median umbilical fold in adults

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5
Q

What does the umbilical vein become in adults?

A

Falciform ligament and round ligament of the liver (left UV)

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6
Q

What is the allantois?

A
  • Vestigal structure in humans, serves as waste storage until bladder forms
  • In birds and lower reptiles, it serves as a respiratory/ waste storage structure

Can cause pathologies in humans if it stays open

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7
Q

What is Meckel’s diverticulum?

A
  • Remnant of vitelline duct in some people, presents as outpouching of intestine

can be connected with fibrous cord to umbilicus (from small intestine)

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8
Q

What does the vitelline vein become in adults?

A

Portal vein

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9
Q

What do the vitelline arteries become in adults? What areas do they supply?

A
  • Celiac trunk (supplies foregut)
  • Superior mesenteric artery (supplies midgut)
  • Inferior mesenteric artery (supplies hindgut)
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10
Q

What structures are in the umbilical cord?

A
  • Umbilical arteries
  • Umbilical veins
  • Vitelline arteries
  • Vitelline veins
  • Vitelline duct
  • Allantois/urachus
  • STEM CELLS
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11
Q

What are caval veins (specific to GI)?

A

Veins that take waste products from intestines to Inferior Vena Cava

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12
Q

What is the stomodeum?

A

(Primitive) oral cavity

  • Ectoderm lined with endoderm
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13
Q

What is the proctodeum?

A

Tubes within the cloaca that later form:

  • Anus
  • Vagina (when female)
  • Urethra
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14
Q

How does the GI tract rotate?

A

Note: starts around 50 days

  1. Intestines herniate into umbilical cord (maybe because there is more space there)
  2. Intestines loops 180 degrees (or so) around the superior mesenteric artery
    - As it grows, the arteries stretch also
    - Parietal peritoneum stretches over duct and arteries as they change in conformation to become the viseral peritoneum
    - As organs stretch into peritoneum, mesentaries form, which do not separate during intestinal looping
  3. Final positioning is ascending, transverse, and descending colon surrounding small intestine
  4. Intestines then fall back in to abdomen once folded
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15
Q

What is a retroperitoneal organ?

A
  • Immovable and fixed organ, does not have a mesentary
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16
Q

What is an intraperitoneal organ?

A
  • Movable organ, has a mesentary
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17
Q

What structures are in the foregut?

A
  • Esophagus
  • Stomach
  • Liver
  • Gallbladder
  • Pancreas
  • Spleen
  • First half of duodenum (and part of second half per Dr. Solunias)

Supplied by Celiac trunk

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18
Q

What structures are in the midgut?

A
  • Last 1/4-1/2 of duodenum
  • Jejunum and Ileum
  • Caecum
  • Appendix
  • Ascending colon
  • Proximal 2/3 transverse colon

Supplied by Superior mesenteric artery

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19
Q

What structures are in the hindgut?

A
  • Distal transverse colon (left 1/3)
  • Descending colon
  • Sigmoid colon
  • Rectum

Supplied by inferior mesenteric artery

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20
Q

How do the liver and its blood supply form?

A
  • Liver cells differentiate and migrate underneath heart (part of yolk sac/gut)
  • Vitelline vein runs through early heart and liver
  • Liver also forms complex network of veins, anastomoses between umbilical veins and vitelline veins
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21
Q

What is the early gallblader-liver connection?

A

The liver and gall bladder forms a fibrous matrix of the septum transversum and endodermal diverticula from gut
- Veins invade within

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22
Q

How does the pancreas form?

A
  • Dorsal pancreas forms across from gallbladder on gut
  • Ventral pancreas forms on opposite side next to gallbladder
  • Ventral pancreas then flips and rotates to same side as dorsal pancreas
  • Ventral and dorsal pancreases then join together, still retain two separate ducts (that connect at one point)

Accessory pancreatic duct is on original dorsal pancreas
Pancreatic duct is on original ventral pancreas

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23
Q

What GI structures are outside peritoneal cavity?

A
  • Pharynx
  • Esophagus
  • Rectum
24
Q

When is the sex of the fetus determined?

A

At the moment of fertilization

25
Q

What does the genital tubercle become in adults?

A

Generally becomes erectile tissues

  • Raphé of penis (line), glans of the penis in males
  • forms the vaginal opening in females
26
Q

Where is the urogenital fold?

A

In the middle of the genital tubercle
- Forms first in an undifferentiated stage of development

Becomes:

  • Raphé of penis (line), glans of the penis in males
  • forms the vaginal opening in females
27
Q

What structure is homologous to the scrotal sacs in males?

A

Labia majora in females

  • Both structures are derived from labiosacral swellings
28
Q

What structures are derivatives of the mesonephric embryonic duct?

A
  • Vas deferens
  • Epididymis
  • Seminal vesicles

Mesonephric duct dissolves in females due to hormonal signals

29
Q

What structures are derivatives of the paramesonephric embryonic duct?

A
  • Oviduct
  • Uterus
  • Upper part of the vagina
  • In males, appendix of the testes is the major remnant
30
Q

What structure in males is homologous to the uterus in females?

A

Prostatic utricle

31
Q

Urogenital triangle borders

A
  • Right and left Ischial tuberosities (of the pelvis) are on respective sides
  • Transverse perineal muscles are superior border
  • Penis/Clitoris and vagina are within this area
32
Q

What are the two erectile tissues?

A
  • Corpora cavernosa- consists of fibrous collagen
  • Corpus spongiosum- thinner than corpora cavernosa

Within fibrous matrix is arterial supply that allows for erection

33
Q

Where is the corpora cavernosa located?

A
  • Right and left sides of shaft of penis in males (there is no opening)
  • On sides of clitoris in females
34
Q

Where is corpus spongiosum located?

A
  • Bulbus penis
  • Glans penis (head)

-As it is, it is not in females, later differentiates to bulb of the vestibule

Note: runs midline along penis, surrounds urethra

35
Q

What is inside the corpus cavernosum?

A
  • Helicine arteries
  • Smooth muscles
  • Collagen
36
Q

How does an erection occur?

A
  • Brain sends messages allowing arteries in penis dilate to twice the diameter, blood enters (blood flow increases 16 fold)
  • Blood stays inside because of TUNICA ALBUGINEA (around corpora cavernosa)
  • The tunica albuginea is multiple layers of tough fibrous material, during erection these fibers slide past each other
  • As a result, venous return pinched off and slows down
  • Relaxation in the brain causes tension in TA to break down, and the layers relax and move back
37
Q

How is semen altered before ejaculation?

A
  • Testes bring small volume of semen with lots of sperm to seminal vesicles
  • Fluid produced in seminal vesicles dilutes semen
  • Goes to prostate from seminal vesicle, where it is diluted further with fluid produced in prostate
  • Semen travels out through the urethra during ejaculation
  • *No liquid is produced in penis itself
38
Q

What are the parts of the urethra and which part is the weakest?

A
  • Prostatic urethra (through prostate)
  • Membranous urethra (in between prostatic urethra and penile urethra; THE WEAKEST)
  • Penile urethra
39
Q

Where is the bulbospongiosus muscle located in males and females?

A
  • Located on bulb of penus (corpus spongiosum) in males

- Becomes a sphincter around the vagina in females (around vestibular bulb)

40
Q

What is the function of the bulbospongiosus muscle in males?

A
  • Spastic movement to aid in ejaculation

- Tightens to help maintain erection

41
Q

What is the homologous female structure to the corpus spongiosum in males?

A

Bulbs of the vestibule/Vestibular bulbs

  • Per Dr. Solunias, this is up for debate
42
Q

What membrane supports the genital structures in males and females?

A

Perineal membrane

43
Q

What is the difference between metanephros and mesonephros?

A

Metanephros is the adult kidney

Mesonephros is the embryonic kidney

44
Q

The prostate is derivative of what structures?

A

Bladder/allantois, cloaca

45
Q

What are the differences between female and male pelvises?

A

In general,

  • females have a wider sciatic notch; in males it is narrower
  • females have a broad pubic area between the pubic bones (u-shaped); in males it is narrower (v shaped)
46
Q

What are the borders of the anal triangle?

A

Anterior: superficial transverse perineal m.m.
Posterior: triangle tip is at coccyx
Lateral borders are from ischial tuberosity to coccyx

Note there is lots of fat in the anal triangle

47
Q

What nervous system controls an erection? Ejaculation?

Generally

A

Parasympathetic system controls erection

Sympathetic system controls ejaculation

48
Q

What tissue is the foreskin of the penis derived from? What is a possible function?

A

Derivative of abdominal wall tissue

Possibly contains cells that cleanse the glans of the penis

49
Q

Which two areas in the body consist of ectoderm lined with endoderm?

A

Oral cavity and the rectum

50
Q

Which anal sphincter muscles are controlled by autonomic vs. voluntary nervous system ?

A

External anal sphincter m.m. is under voluntary control

Internal anal sphincter m.m. is under autonomic control

51
Q

What is the function of levator ani muscles? What are the muscle names?

A

To hold anus in pelvic area

  • pubococcygeus
  • puborectalis
  • iliococcygeus
52
Q

What is the epoöphoron?

A

Remnant of the epididymis precursor, found in females

53
Q

What does the upper gubernaculum become in adults ?

A

Ovarian ligament in females (connects ovary and uterus) , entire gubernaculum becomes scrotal ligament in males

54
Q

What does the lower gubernaculum become in adults

A

Round ligament of the uterus (connects anal canal with labia Majora) in females
In males, entire gubernaculum becomes scrotal ligament

55
Q

What is the main blood supply in the perineal area?

A

Mostly Branches off the common iliac artery, named in relation to where they supply blood
- i.e. Lateral sacral artery, middle rectal artery, internal pudendal artery, vaginal artery, uterine artery,

56
Q

What is the main nerve supply for the genital/ perineal area?

A

Sacral plexus nerves, main nerve is the pudendal nerve to the genitalia/perineum
- inferior rectal n., perineal n.n. (Deep and superficial), posterior scrotal n. n., dorsal nerve of the penis are branches of the pudendal n.

Pudendal n. Does NOT supply internal anal sphincter

57
Q

Which structure is immediately internal to the pubic symphisis?

A

Bladder

Foundations (9 decks)

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