Abdomen Flashcards
major classes of fascia of the abdominal wall
Superficial fascia- in lower region of abdominal wall forms two layers: superficial fatty layer and deeper membranous layer
Transversalis fascia- continuous layer of deep fascia that lines abdominal cavity and continues into pelvic cavity
Extraperitoneal fascia- deep to the transversalis fascia separates it from peritoneum
What is the deepest layer of fascia of the anterior abdominal wall
Transversalis fascia
The abdominal cavity
Largest anatomical cavity
Lies under cover of lower ribs and diaphragm
Some of the abdominal cavity projects backwards into the pelvis in front of buttocks
Continuous with the pelvic cavity = abdominal-pelvic cavity
Cavity for: digestive tract and late pregnancy
Prominent visual features of anterior abdominal wall
Epigastric region
Umbilicus
Periumbilical region
Hypogastric region
Anterolateral wall tissues and muscles
Anterior superior iliac spine
Iliac crest
Pubic tubercle
Linea alba
Theoretical landmarks of importance
Semilunar line
Transplyoric plane- separates umbilical region from epigastric
Trans-tubercular plane- separates umbilicus from hypogastric
Spino-umbilical line (RHS)
McBurney’s point
Mid-clavicular line
Mid-inguinal point
Arcuate line
Mid inguinal point
Important surgical landmark forms midpoint of imaginary line that joins anterior superior iliac spine and pubic symphysis
Marks positions where external iliac artery leaves the abdomen to become femoral artery
Point at which femoral pulse is palpated
Deep inguinal ring is medial to it
McBurney’s point
Point over right side of abdomen that’s 1/3 distance from anterior superior iliac spine to the umbilicus
Roughly corresponds to most common location of the base of the appendix where it’s attached to caecum
Gross anatomical features of the abdominal cavity
Boundaries:
Diaphragm- superior
Pelvic brim - inferior/imaginary
Anterolateral abdomino-pelvic wall- derivative of body wall
Posterior abdominal wall
Tissue layers of anterior abdominal wall
Skin
Superficial fatty layer or subcutaneous tissue (camper fascia)
Deep membranous layer subcutaneous tissue (scarpa fascia)
Superficial layer deep fascia
External oblique
Intermediate layer deep fascia
Internal oblique
Deep layer of deep fascia
Transversus abdominis
Endoabdominal (transversalis) fascia
Extraperitoneal fat
Parietal peritoneum
General design of body wall
Skin
Superficial fascia- with or without subcutaneous fat
Deep fascia
Muscles of body wall
Endothoracic or endoabdominal or transversalis fascia
Linea alba
Fibrous structure that runs down midline of abdomen
Rectus sheath
Also called rectus fascia
Multilayered aponeurosis, fibrous sheath of dense regular connective tissue
Formed by aponeurosis/tendons of the transverse abdominal and internal and external oblique muscles
Rectus sheath envelopes rectus abdominis muscle-abs
2 sets of muscles of the anterolateral wall of abdomen
Lateral group= anterolateral muscles, abdominal continuation of muscles of thoracic wall
Midline group= rectus abdominis, pyramidalis, thoracic equivalent must be sternum
Arcuate line
Known as the semicircular line of Douglas
Curved line found posterior to the rectus abdominis muscle bilaterally
Occurs about 1/2 distance from umbilicus to pubic crest
Important clinical site in which the anterior wall could herniate
Anatomical landmark that determines the nature of tissue layers of the rectus sheath
Tissue layers of rectus sheath above Arcuate line are different form those below
If one dissects anterolateral abdominal wall the Arcuate line may be difficult to see as all aponeurosis are translucent
Tissue layers of the rectus sheath superior to Arcuate line
Aponeurosis of external oblique passes anterior to the rectus abdominis muscle
Aponeurosis of internal oblique splits to surrounded rectus abdominis
Posterior to rectus abdominis is the aponeurosis of the transversus abdominis as well as transversalis fascia
Tissue layers of the rectus sheath inferior to Arcuate line
Aponeurosis of the internal oblique and the transversus abdominis pass anteriorly to the rectus abdominis muscle instead of surrounding
Transversalis fascia is only structure located posteriorly
Surface map of anterior abdominal wall 2 methods
Abdominopelvic quadrants
9 compartments of abdominopelvic region
Based on physically palpable anatomical structures
Standardises mapping surface of the body between patients
Useful in surface palpation of major abdominal organs
Abdominopelvic quadrants
Points of reference are:
Linea alba- vertical line
Xiphoid process
Pubic symphysis
The umbilicus - horizontal line
Divides region into RUQ, LUQ, RLQ, LLQ
RUQ= liver and gall bladder
LUQ=stomach, pancreas, spleen
LLQ=descending colon and part of ilium
RLQ=ascending colon, appendix
9 abdominal compartments by surface mapping
2 vertical planes:
-one on each side of midline, a line joining the mid clavicular point to the mid inguinal point, passes just lateral to tip of 9th costal cartilage
2 horizontal planes:
-subcostal plane- a line drawn joining the lowermost bony point of the rib cage- usually 10th costal cartilage, body of L3 vertebra; origin of the inferior mesenteric artery and 3rd part of duodenum lie on this plane
-trans-tubercular plane- a line uniting the 2 tubercles of the iliac crest, upper border of L5 vertebra and the confluence of the common iliac veins (IVC origin) lie on this plane
Right and left hypochondriac regions and epigastric region
Subcostal plane
Right and left lumbar regions and umbilical region
Transtubercular plane
Right and left iliac region and hypogastric region
What is peritoneum
Simple squamous epithelium
Also known as pavement epithelium
One cell thick tissue membrane
Lines the:
-interior surfaces of all of abdominal wall: except area of coronary ligament (small area between liver and diaphragm known as bare area of liver)
-surfaces of all viscera of abdomen except bare area of liver
2 types of peritoneum: parietal and visceral, they’re continuations of the same layer of membrane
Innervation of peritoneum
Parietal peritoneum: lines inner walls of abdomen, diaphragm and pelvis, innervated by sensory division of the somatic nervous system- pain sensations are sharp and localised
Visceral peritoneum: lines visceral organs of the abdomen, innervated by the sensory division of the autonomic nervous system, pain sensations are not localised but perceived as non defined discomfort e.g. indigestion
The bare area of the liver
Part of liver that’s not covered by visceral peritoneum
Occurs when parietal peritoneum on inferior surface of diaphragm dives inferiorly to cover surface of liver
Coronary ligament
Important clinically because it has no sensory or nervous innervation so if there’s a pathological development patient wont be aware
Compartments of abdominal cavity
Peritoneal compartment
Intraperitoneal compartment
Extraperitoneal compartment
-retroperitoneal compartment/space
Structures of abdomen lie in these locations
Intraperitoneal
Secondary retroperitoneal
Primary retroperitoneal
These locations differ in accessibility and mobility
There’s no organs found within the peritoneal compartment
Peritoneal cavity (abdominal cavity)
The cavity created between the parietal and visceral peritoneum
Derived from coelomic cavity of embryo: others being the pleural cavities and the pericardial cavity
The largest fluid filled cavity in body
Secretes ~50ml fluid per day
Fluid acts as a lubricant and has anti-inflammatory properties
Intraperitoneal cavity
Visceral organs that are completely covered in visceral layer of peritoneum effectively create a compartment in which they’re contained in
This is the intraperitoneal cavity
Known as intraperitoneal organs
What is a mesentery
Double layer of visceral peritoneum
Continuous folded band that’s attached to wall of abdomen and encloses the viscera
Attaches intestines to the posterior abdominal wall
Sub classification of extra-peritoneal organs
Lying in front peritoneal sac:
-pre-peritoneal structures
-exists only conceptually- normally no structure found in this area
-this space can be invaded pathologically at level of pelvis
Lying behind peritoneal sac:
-post or retro-peritoneal structures
Laparoscopic access to the peritoneal cavity
Formally divisible into:
The greater sac
The lesser sac
The omental foramen (epiploic foramen of Winslow) is the window that allows for communication between the greater and lesser sac
Double folds of peritoneum can be referred to as
Ligament
Omentum
Mesentery
Omenta
Consist of 2 layers of visceral peritoneum which pass from stomach and first part of duodenum to other viscera
Greater omentum- derived from dorsal mesentery
Lesser omentum- derived from ventral mesentery
Greater omentum
Large double visceral peritoneal fold that attaches to the greater curvature of the stomach and first part of duodenum
Drapes inferiorly over transverse colon and the coils of jejunum and ileum
Turning posteriorly it ascends to become adherent to the peritoneum on the superior surface of transverse colon and anterior layer of transverse mesocolon before arriving at posterior abdominal wall
Contains accumulation of fat, peritoneal fluid and white blood cells. and there’s 2 arteries and accompanying veins= the right and left gastro-omental vessels
Lesser omentum
Extends from the lesser curvature of stomach and first part of duodenum to inferior surface of liver
Divided into:
-A medial hepatogastric ligament which passes between the stomach and liver
-a lateral hepatoduodenal ligament which passes between duodenum and liver. Ends laterally as a free margin and serves as the anterior border of the omental foramen
Enclosed in this free edge are the hepatic artery proper, bile duct and portal vein
The left and right gastric vessels are between layers of lesser omentum near lesser curvature of stomach
Mesenteries
Visceral Peritoneal folds that attach viscera to posterior abdominal wall
They allow some movement and provide a conduit for vessels, nerves and lymphatics to reach viscera
Include:
The mesentery: associated with parts of small intestine
The transverse mesocolon: associated with transverse colon
The sigmoid mesocolon: associated with sigmoid colon
Ligaments
Consists of two layers of peritoneum that connect 2 organs to each other or attach an organ to body wall, and may form part of an omentum
E.g. splenorenal ligament, gastrophrenic ligament
Divisions of the peritoneal cavity
Right subphrenic space
left suphrenic space
Subhepatic space
Right and left paracolic gutter
Right and left inframesocolic space
Pelvis