Lecture 2

Question 1

What composes the Superior Boundary of the abdomen?

Answer 1

Diaphragm
Inferior Thoracic Aperture (bottom of rib cage)
-Abdomen pops up 1/2 way into Thoracic cavity (rib 5) changes with inspiration and expiration

Question 2

What composes the Inferior Boundary of the abdomen?

Answer 2

Illiac Crest
Inguinal Ligament
Pelvic Inlet (everything below is pelvic region)

Question 3

What composes the Posterior Boundary of the abdomen?

Answer 3

Lumbar Vertebral Column
Psoas Major
Quadratus Lumborum
(abdominal wall muscles)

Question 4

What composes the Lateral and Anterior Boundary of the abdomen?

Answer 4

Abdominal Wall Muscles

Question 5

9x Layers of the Abdominal Wall (External –> Internal)

Answer 5

1. Skin
Superficial Fascia (x2)
2. Camper's Fascia (thick yellow fatty, all over abdomen)
3. Scarpa's Fascia (Below Umbilicus, more orange, continuous with Dartus fascia and Collis fascia in you pertioneum)
Muscle 3x
4. External Oblique
5. Internal Oblique
6. Transversus Abdominis
7. Transversalis Fascia
8. (Extra peritoneal Fascia)
9. Parietal Peritoneum

Question 6

What is the variation between the Superficial Fascia as you go down the abdomen?

Answer 6

Above Umbilicus: Superficial fascia is same as everywhere else in body (thick, fat yellow layer)
Below Umbilicus: divides into 2x layers:
Superificial (fatty)= Campers Fascia= contains BV and nerves
Deep (membranous)= Scarpa’s Fascia

Question 7

Where does the Abdomen span from?

Answer 7

Inferior Thoracic Aperture –> Top of the Pelvis

up into Thorax - down into the pelvis

Question 8

What are the functions of the abdominal wall muscles?

Answer 8

1. Stability (hold thorax and core up)

2. Allows Abdominal Viscera to move (flexible wall for movement/eating/pregnancy)

Question 9

Rectus Abdominis

Answer 9

Longitudinal muscle, running down midline
Origin: Pubic Tubercle, Crest and Symphysis (Midline on Pubi bones)
Insertion: Costal Cartilages ribs 5-7 & Xiphoid Process (not on ribs or inferior thoracic aperture)
Action: - Flex Trunk. (pelvis more stable) -Support/compress Abdominal Wall (secondary respiratory muscle: tense abdominal muscles to compress abdominal cavity, and force luns up = forced expiration)
Nerve: Anterior Rami of Thoracic Spinal Nerves

Question 10

External Oblique

Answer 10

Origin: Ribs 5-12
Insertion: Iliac Crest & Linea Alba (Inguinal Ligament) via aponeruosis (has no bone, so forms strong tendinous attachment)
Aponeruosis: From xiphoid process to pubic symphosis (lower border forms inguinal ligament)
-inguinal ligament= Rolled border of external oblique . Creates a gap for Femoral vessels to pass underneath.
Action: -Flex trunk (both) -turn to Opposite side/bend trunk to same side (single)
Nerve: Anterior Rami of thoracic Spinal Nerves
Fibre Direction: Infero-medial (hands in pockets)(downwards orientation)

Question 11

Internal Oblique

Answer 11

Origin: Thoracolumbar Fascia (back), Inguinal Ligament & Illiac Crest
Insertion: Ribs 9-12
Action: -Flex trunk (both). -bend & turn trunk to Same side (single)
Nerve: Anterior Rami of Thoracic Spinal Nerves (some L1)
Fibre Direction: Supero-medial (as originates off inguinal ligament)

Question 12

What is the relationship between External and Internal Oblique when they’re both firing?

Answer 12

Both flex trunk
Antagonisticly with other side
Turn to left: Right external and Left Internal fire
(works with opposite side)

Question 13

Transversus Abdominis

Answer 13

Origin: Thoracolumbar Fascia (back), Iliac Crest, Inguinal Ligament, Costal Cartilage Rib 7-12
Insertion: Linea Alba (midline meeting of all aponeurosis’), Pubic crest, Pectineal Line (same place as rectur abdominis)
Action: Supports abdominal wall (not much of a movement function)
Nerve: Anterior Rami of thoracic spinal nerves (some L1- nerve run inbetween transversus abdominus and internal oblique, and innvervates a little bit along the way)
Fibre Direction: Transverse

Question 14

Rectus Sheath

Answer 14

Over Rectus Abdominus
Aponeurosis of all other muscles to meet in midline
Supportive
Tough tendinous
Upper 3/4= all 3x abdominal muscles fully surround- Internal oblique splits (other 2x stay)
Lower 1/4 = below Arcuate Line= all 3x abdominal muscle are infront of rectus abdominus =(behind is Transversalis Fascia and Parietal Peritoneum) (not supported at back, relatively weak area, allows vessels to pass through, can result in hernia) (clinically important to know you have this deficit)

Question 15

Arcuate Line (Rectus Sheath)

Answer 15

Roughly half way along line from Umbilicus to Pubic bones = Posterior wall of rectus sheath stops. Only have transversalis Fascia.
Tough tendinous sheath –> see-through shimmery layer (lost strong aponeurotic tissue)
-Arcuate line is where arterial supply enters/gets in

Question 16

Arterial Supply

Answer 16

Superior Epigastric A. (from Internal Thoracic)
Inferior Epigastric A. (from External Illiac)- more dominant/much larger
Both run underneath Rectus Abdominus - (ontop of Transversalis Fascia - Within rectus Sheath) 
(Inferior epig, pierces through transversalis fascia, runs ontop and into rectus sheath)
Anastomose together(in middle)
Also: Deep Circumflex illiac, Musculophrenic branches, intercostal, lumbar, illiolumbar

Question 17

Venous Drainage

Answer 17

Thoraco-epigastic Veins: Drain to Axillary (to armpit)

Superficial Epigastic Veins: Drains to femoral

Question 18

Nerves

Answer 18

Lateral Cutaneous Branches 7-12 intercostal nerves + iliohypogastric nerve (L1) (lateral branches span around innervating lateral part)
Anterior Cutaneous branches of 7-12 intercostal nerves (anterior branches poke through lateral to rectus abdominis, innervating anteriorly)
-lower 6 interocstal nerves + hypogastic L1
-travel in neurovascular plane b/w Internal Oblique and Transversus Abdominis (analagous to nerves of intercostal plane)

Question 19

Abdominal Dermatomes

Answer 19

1x nerve= 1 band (segmental spinal nerves which innervates 1x band)
Skin + Muscle + Parietal Peritoneum = supplied by T7-T12(intercostal) & L1 (illiohypogastric/Illioinguinal) spinal nerves
All= Anterior Rami (lateral and anterior)
T4-5= nipples
T10= umbilicus
Neurovascular plane: b/w Transversus Abdominis and Internal Oblique -analagous to Intercostal Neurovascular Plane - before piercing muscular wall to reach skin
(Referred pain in gut)

Question 20

Lymphatic Drainage

Answer 20

Superficial Inguinal (inferiorly)
Anterior Axillary (superior)
Posterior Axillary

Question 21

Peritoneum

Answer 21

Visceral: covers abdominal viscera (organs) + forms Mesentary -anchors viscera to Posterior body wall) (viscera comes back around on itself)
- GI tract/tube suspended in space by mesentery. 2x layers of visceral pertioneum. how BV come from Aorta and get into gut by travelling within mesentery.
Parietal: Lines body wall
Continuous with one another
Small amount of serous fluid between layers: reduces friction (created by movement)
-allows abdominal viscera to move without causing ulceration

Question 22

Sensation of Peritoneum

Answer 22

Parietal: Sensitive to pain, touch, temperature and pressure. (body wall)
-Nervous supply by 1. Somatic nerves to body wall (Thoracic + Lumbar nerves) 2. Phrenic nerve (up by diaphragm) 3. Obturator nerve (down in pelvis)
Visceral/Mesenteries: Sensitive to stretch - Autonomoic NS Afferent fibres. (woudlnt feel if you poke gut)
-Stretching/Distension (eat too much)

Question 23

Mesenteric Peritoneum

Answer 23

GI tract/gut tube passively suspended by Mesenteries
Mid + Hind gut= suspended by only 1x mesentery (Dorsal)
Foregut= suspended by BOTH ventral and dorsal mesentery. Where Umbillical cord enters, Umbillical veins go to liver, Liver part of Foregut (Mesenteric route for veins to enter) -gut embryology + ligaments of foregut

Question 24

Intraperitoneal

Answer 24

completely contained in Visceral peritoneum
Suspended by Mesentery
-Spleen, Liver, Gall bladder, Spleen, Proximal Duodenum, Small Intestine, Appendix, Transverse Colon, Sigmoid Colon
(GI, most of foregut, bits of mid + hindgut)

Question 25

Retroperitoneal

Answer 25

b/w peritoneum and body wall
(partial peritoneal cover)
“sitting behind” have muscle or fat behind
-kidneys, pancreas, distal duodenum, Ascending + Descending colon, Upper 2/3 of Rectum
Note: Extraperitoneal:(not peritoneum) + Infraperitoneal (pelvis)

Question 26

Greater Sac

Answer 26

Peritoneal Cavity Proper

• everything thats not lesser sac
• air and fluid inside

Question 27

Lesser Sac

Answer 27

Omental Bursa
Behind Lesser omentum (peritoneum spanning from liver to stomach) and stomach (and a liver lil bit)
-created due to rotation of foregut structures
-drags Lesser omentum round to create pocket
-Folds back on itself to form free edge
“Blind ended sac”
Bounded anteriorly: Free edge of Lesser omentum (containing portal triad)
Bound Posteriorly: by IVC
Omental/Epiploic Foreamen = Foreamen of Winslow
-in free edge of lesser omentum are Biliary structures (hepatic artery, portal vein, bile duct)
-clinically important for fluid movement- get migrations and pains

Question 28

Paracolic Gutters

Answer 28

Peritoneal sulci lateral to ascending/descending colons -gutter
-allows fluid to be moving around body
Create a pathway for peritoneal fluids (or pus, bile, blood etc) to migrate around the abdomen
(trauma)
Right = slightly more clinically significant.
-Larger. (superior hepatic recess + lesser sac)
-it’s peritoneum continuous with peritoneum of Hepatic recess + Lesser Sac
Left= limited by phrenico-colic ligament (usually)
Clinical significance: Fluid migration can cause pain at sites distal to affected organ
Sitting: fluid migrate down, presenting as Acute Appendicitis
-Liver problem(blood pus), sit up, force of gravity takes fluid down right paracolic gutter and collects at bottom against body wall. Parietal peritoneum sensitive to pain+ pressure, pressure build up as fluid collects = sharp acute pain in lower right quadrent (assume/presents to be appendicitis)
Supine(lying down): (less force of gravity) fluid migrates to lesser sac + collects (when stand up again, cant get out so sits in lesser sac. If puss and bile, collects in lesser sac, potential Abcess formation. Distal to site of pathology)
-important to consider when examining patients