Anatomy Flashcards

1
Q

Retroperitoneal structures include GI structures that lack mesentery and non-GI structures.

Injuries to retroperitoneal structures –> blood gas accumulation in retroperitoneal space

A

Suprarenal (adrenal) glands

Aorta + IVC

Duodenum (2nd through 4th parts)

Pancreas (except tail)

Ureters

Colon (descending and ascending)

Kidneys

Esophagus (thoracic portion)

Rectum (partially)

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2
Q

Important gastrointestinal ligaments (6)

A
  1. Falciform
  2. Hepatoduodenal
  3. Gastrohepatic
  4. Gastrocolic
  5. Gastrosplenic
  6. Splenorenal
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3
Q

Falciform ligament

A
  • Connects: liver to anterior abdominal wall
  • Structures contained:
    • Ligamentum teres hepatis (derivative of fetal umbilical vein)
  • Notes:
    • Derivative of ventral mesentery
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4
Q

Hepatoduodenal ligament

A
  • Connects: liver to duodenum
  • Structures contained:
    • Portal triad - proper hepatic a., portal vein, common bile duct
  • Notes:
    • Pringle maneuver - ligament may be compressed between thumb and index finger (placed in omental foramen to control bleeding)
    • Borders omental foramen (foramen of Winslow), which connects greater and lesser sacs
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5
Q

Gastrohepatic ligament

A
  • Connects liver to lesser curvature of stomach
  • Structures contained:
    • Gastric arteries
  • Notes:
    • Separates greater and lesser sacs on the right
    • May be cut during surgery to access lesser sac
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6
Q

Gastrocolic ligament

A
  • Connects greater curvature and transverse colon
  • Structures contained:
    • Gastroepiploic arteries
  • Notes:
    • Part of greater omentum
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7
Q

Gastrosplenic ligament

A
  • Connects: Greater curvature and spleen
  • Contains:
    • Short gastrics, left gastroepiploic vessels
  • Notes:
    • Separates greater and lesser sacs on the left
    • Part of greater omentum
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8
Q

Splenorenal ligament

A
  • Connects: Spleen to posterior abdominal wall
  • Structures contained:
    • Splenic artery and vein, tail of pancreas
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9
Q

Digestive Tract Anatomy

Layers of the gut (inside to outside - MSMS)

A
  • Mucosa - epithelium, lamina propria, muscularis mucosa
  • Submucosa - includes submucosal nerve plexus (Meissner), secretes fluid
  • Muscularis externa - includes myenteric nerve plexus (Auerbach), motility (inner circular layer, outer longitudinal layer)
  • Serosa (when intraperitoneal), adventitia (when retroperitoneal)
    • Vasculature
    • Lymphatics

Ulcers can extend into submucosa, inner or outer muscular layer.

Erosions = mucosa only

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10
Q

Frequencies of basal electric rhythm (slow waves)

A
  • Stomach - 3 waves/min
  • Duodenum - 12 waves/min
  • Ileum - 8-9 waves/min
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11
Q

Digestive Tract Histology

Esophagus

Stomach

A
  • Esophagus:
    • nonkeratinized stratified squamous epithelium
  • Stomach:
    • gastric glands
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12
Q

Digestive Tract Histology

Duodenum

Jejunum

Ileum

Colon

A

Duodenum:

  • villi and microvilli increase absorptive surface
  • brunner glands (HCO3- secreting cells of submucosa)
  • crypts of Lieberkuhn

Jejunum

  • plicae circulares
  • crypts of lieberkuhn

Ileum

  • Peyer patches (lymphoid aggregates in lamina propria, submucosa)
  • Plicae circulares (proximal ileum)
  • crypts of lieberkuhn
  • Largest number of goblet cells in small intestine

Colon

  • crypts of lieberkuhn but NO VILLI
  • Abundant goblet cells
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13
Q

Abdominal aorta and branches

T12

L1

L2

L3

L4

L5

A

Arteries supplying GI structures branch anteriorly.

Arteries supplying non-GI structures branch laterally and posteriorly.

  • T12: IVC (Right), Celiac trunk, Middle Suprarenal
  • L1-L2: SMA, Renal, Gonadal (testicular/ovarian)
  • L3: IMA
  • L4: “BiFOURcation”
  • L5: R & L common iliac (w/ R & L internal iliac coming off), median sacral artery
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14
Q

SMA (Wilkie’s) Syndrome

A

Intermittent intestinal obstruction symptoms (primarily postprandial pain) when transverse (third) portion of duodenum is compressed between SMA and aorta

Typically occurs in conditions associated with diminished mesenteric fat (e.g., low body weight/malnutrition)

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15
Q

GI Blood Supply and Innervation:

Foregut

A

Artery: Celiac trunk (L gastric, common hepatic, splenic)

PSNS: Vagus

SNS: T5-T11

Vertebral level: T12-L1

Structures supplied:

  • Pharynx (vagus nerve only), lower esophagus (celiac artery only) to proximal duodenum
  • Liver, gallbladder, pancreas, spleen (mesoderm)
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16
Q

GI Blood Supply and Innervation:

Midgut

A

Artery: SMA

PSNS: Vagus

SNS: T11-T12

Vertebral level: L1

Structures supplied:

  • Distal duodenum to proximal 2/3 transverse colon
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17
Q

GI Blood Supply and Innervation:

Hindgut

A

Artery: IMA

PSNS: S2-S4

SNS: L1-L2

Vertebral level: L3

Structures supplied:

  • Distal 1/3 transverse colon to upper portion of rectum
18
Q

Celiac Trunk = main blood supply of stomach

Strong anastomoses exist between:

A

Common hepatic artery, L gastric a., splenic artery

Anastomoses:

L and R gastroepiploics

L and R gastrics

19
Q

Portosystemic anastomoses (3)

Site of anastamosis:

Clinical Sign:

Portal <–> Systemic:

A
  1. Esophagus
    1. Esophageal varices
    2. Left gastric <–> azygos
  2. Umbilicus
    1. Caput medusae
    2. Paraumbilical <–> small epigastric veins of anterior abdominal wall
  3. Rectum
    1. Anorectal varices
    2. Superior rectal <–> middle and inferior rectal
20
Q

Treatment for portal HTN

A

TIPS (transjugular intrahepatic portosystemic shunt) b/w portal vein and hepatic vein relieves portal HTN by shunting blood to systemic circulation, bypassing liver

21
Q

Pectinate (dentate) line

A

Formed where endoderm (hindgut) meets ectoderm

22
Q

Above pectinate line issues

Blood supply

Lymphatic drainage

A

Internal hemorrhoids, adenocarcinoma

**Internal hemorrhoids receive visceral innervation –> not painful

Arterial supply: superior rectal artery (branch of IMA)

Venous drainage: superior rectal vein –> inferior mesenteric vein –> portal system

Lymphatic drainage to internal iliac lymph nodes

23
Q

Below pectinate line issues

Blood supply

Lymphatic drainage

A

External hemorrhoids, anal fissures, SCC

**External hemorrhoids receive somatic innervation (inferior rectal branch of pudendal n.) –> PAINFUL if thrombosed

Arterial supply: inferior rectal artery (branch of internal pudendal a.)

Venous drainage: inferior rectal vein –> internal pudendal vein –> internal iliac vein –> common iliac vein –> IVC

Lymphatic drainage to superficial inguinal nodes

24
Q

Anal Fissure

Description:

Association:

A

Tear in anal mucosa below pectinate line

  • Pain while pooping
  • Blood on toilet Paper
  • Located Posteriorly b/c area is Poorly Perfused

Associated with low-fiber diets and constipation

25
_Liver tissue architecture_ What does the apical surface of hepatocytes face? What does the basolateral surface face? Kupffer cells? Hepatic stellate (Ito) cells?
Apical: Bile canaliculi Basolateral: sinusoids Kupffer cells **(specialized macrophages)** form lining of sinusoids Hepatic stellate (Ito) cells in space of Disse store **vitamin A (when quiescent) and produce ECM (when activated)**
26
Zone I, II, III
Zone I - periportal zone * Affected 1st by viral hepatitis * Ingested toxins (e.g., cocaine) Zone II - intermediate zone * Ye**ll**ow fever Zone III - pericentral vein (centrilobular) zone * Affected 1st by ischemia * Contains cytochrome P-450 system * Most sensitive to metabolic toxins * Site of alcoholic hepatitis
27
Biliary Structures Gallstones --\> symptoms Tumors that arise in head of pancreas (usually ductal adenocarcinoma) can cause what?
Gallstones (filling defects) that reach confluence of **common bile duct** and **pancreatic ducts at ampulla of Vater** can block both common bile and pancreatic ducts **(double duct sign),** causing both **cholangitis and pancreatitis** respectively. Tumors that arise in head of pancreas --\> obstruct common bile duct --\> painless jaundice
28
Femoral region organization (lateral to medial) Femoral triangle borders: Femoral sheath:
Nerve-Artery-Vein-Lymphatics _Femoral triangle borders:_ * Medial: adductor longus * Lateral: Sartorius * Superior: Inguinal ligament _Femoral sheath:_ Fascial tube 3-4 cm below inguinal ligament (contains femoral vein, artery, and canal - deep inguinal lymph nodes.... but NOT femoral nerve)
29
Inguinal canal
Internal spermatic fascia (transversalis fascia) Cremasteric muscle and fascia (Internal oblique) External spermatic fascia (External oblique)
30
Hernias Complicated hernia presentation
Protrusion of peritoneum through an opening, usually at a site of weakness Contents at risk for **incarceration** (not reducible back into abdomen/pelvis) and **strangulation** (ischemia and necrosis) Complicated hernia presentation: tenderness, erythema, fever
31
Diaphragmatic hernia Most commonly a **hiatal hernia** (stomach herniates upward through esophageal hiatus of diaphragm) - 2 types
Abdominal structures enter thorax; may occur due to congenital defect of pleuroperitoneal membrane, or as a result of trauma Commonly occurs on **L side** due to relative protection of right hemidiaphragm by liver **Sliding hiatal hernia:** most common (GEJ displaced upward; "hourglass stomach") **Paraesophageal hernia:** GEJ normal --\> fundus protrudes into thorax
32
Indirect inguinal hernia
_Indirect Inguinal Hernia_ Goes through **in**ternal (deep) inguinal ring, external (superficial inguinal ring), and **in**to scrotum --\> follows path of descent of testes... covered by all 3 layers of spermatic fascia Enters internal inguinal ring LATERAL to inferior epigastric vessels Occurs in **in**fants owing to failure of processus vaginalis to close (can form hydrocele); much more common in males
33
What is the **cause** of indirect hernias?
Patent Processus Vaginalis (allows communication b/w peritoneum and testes)
34
Direct Inguinal Hernia
_Direct Inguinal Hernia_ * Protrudes through **inguinal (Hesselbach) triangle** * Inferior epigastric vessels * Lateral border of rectus abdominis * Inguinal ligament * Bulges directly through abdominal wall **medial** to inferior epigastric vessels * Goes through external (superficial) inguinal ring only * Covered by external spermatic fascia * Usually in elderly men (weak abdominal muscles - **transversalis fascia**)\*\*\* \*\*MDs don't LIe
35
Femoral hernia
Protrudes below inguinal ligament through femoral canal below and lateral to pubic tubercle More common in **fem**ales More likely to present with incarceration or strangulation than inguinal hernias
36
The diaphragm is derived from **four** embryonic structures.
1. Septum transversum 2. Pleuroperitoneal membranes 3. Mesoderm of body wall 4. Mesoderm of esophagus
37
What is the most common type of hernia?
**Bochdalek hernia** Occurs in **posterolateral portion** of diaphragm
38
Mesenteries divide coelomic cavity into R and L halves. Upper abdomen: Stomach and gut are suspended in the middle. Liver is suspended in _______ mesentary. Spleen is suspended in _______ mesentary.
Liver is suspended in **ventral** mesentary. * Persists as _hepatic ligaments and lesser omentum_ * _​_Falciform ligament (remnant of ligamentum teres) * Lesser omentum * Hepatogastric * Hepatoduodenal Spleen is suspended in **dorsal** mesentary.
39
**Dorsal Mesentary** derivatives
Greater Omentum * Gastrocolic * Gastrosplenic * Splenorenal * Mesentery of small intestine * Mesocolon
40
Anterior Abdominal Wall: Anatomy **above and below arcuate line**
41
What is the surgical landmark for appendicitis?
Teniae coli Begins as a continuous layer of longitudinal muscle that surrounds rectum just below serosa... at **rectosigmoid jxn**, this layer condenses to form **3 distinct longitudinal bands** that travel on the outside of the entire colon before **converging** at the root of the appendix