Osteopathy Journals and Research by Darren Chandler

 

Endoabdominal fascia

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The endoabdominal fascia lines the abdominal cavity. It is comprised of:

  • Transversalis fascia: outer layer. Lies between the inner surface of the transverse abdominis muscle and the extraperitoneal tissue. 
  • Extraperitoneal tissue: this is a layer of connective tissue between the transversalis fascia and parietal peritoneum.
  • Parietal peritoneum (or fascia): this layer is a thin serous membrane acting as a balloon which lines the abdomen and into which the organs are pressed into from the outside. 
  • Visceral peritoneum (or layer): this layer lines the organs and is known as the visceral peritoneum in the abdomen, pleura in the thorax (Gallaudet, 1931) and pericardium around the heart.

Transversalis fascia

Li (2012) defined the transversalis fascia as lining the inner surface of the transversus abdominis. It can be divided into two layers, superficial and deep, with a dividing intermediate layer between the two:

  • Superficial layer of the transversalsis fascia: closely covers the internal surface of the transversus abdominis and its aponeurosis.
  • Intermediate layer: is an amorphous fibroareolar space filled with fat and loose fibrous tissue. It lies between the superficial and deep layers of the transversalis fascia.
  • Deep layer of the transversalis fascia: a loose amorphous fibroareolar space lies between the deep layer of the transversalis fascia and the peritoneum.

Superiorly

Superiorly the superficial and deep layers fuse and blend with the fascia covering the inferior surface of the diaphragm. Forming the subdiaphragmatic fascia the transversalis fascia travels through the medial and lateral arcuate ligaments and aortic hiatus to become the endothoracic fascia. 

Anteriorly

Anteriorly the superficial layer covers the inner surface of the transversus abdominis and the posterior rectus sheath (or rectus abdominis). The deep layer lines the outer surface of the peritoneum.

Posteriorly

Posteriorly the superficial and deep layers join together and form a continuous sheet anterior to the lumbar fascia.

From anterior to posterior the transversalis fascia courses over the quadratus lumborum and then the psoas major. At these points the transversalis fascia gets renamed the quadratus lumborum and psoas fascia respectively.

As the transversalis fascia is the fascia of the quadratus lumborum and psoas whilst extending superiorly to form the subdiaphragmatic fascia it forms the arcuate ligaments.

The lateral arucate ligament (rib 12 to L1 TP) is a thckening of the quadratus lumborum fascia. The medial arcuate ligament (L1 body to L1 TP) is a thickening of the psoas fascia.

Laterally

Laterally Li et al (2012) found the superficial and deep layers to join at the:

  • Outer edge of the quadratus lumborum (at the level of the renal hilum)
  • The outer edge of the psoas major (at the level of L3).
  • Anterior axillary line.

Also at the outer edge of the quadratus lumborum the transversalis fascia blends with the lateral conal fascia* (Li et al 2012).

*: Lateral conal fascia is formed by the lateral fusion of the anterior and posterior renal fascia. Travels laterally inrelation to the posterolateral aspect of the colon and fuses with the lateral parietal peritoneum.

Inferiorly

Inferiorly the transversalis fascia is continuous with the endopelvic fascia.

Inferiorly Meyer (1927) found the transversalis fascia, along with the pelvic fascia with which it is continuous, tightly adheres to the pelvic brim. Hayes (1950) found anteriorly at the pelvic brim the transversalis fascia blends with the periosteum of the dorsal surface of the superior pubic ramus and pubic crest.

Spaces between the superficial and deep layers of transversalis fascia

The spaces between the superficial and deep layers of the transversalis fascia are:

  • Extraperitoneal space: the space between the superficial and deep layers of the transversalis fascia.
  • Retroperitoneal space: space behind the peritoneum in the abdominal cavity.
  • Retzius space: the space between the symphysis pubis and bladder. The superficial branch of the deep dorsal vein of the penis in Retzius space penetrates the superior layer of the transversalis fascia to drain into the deep dorsal vein of the penis. 
  • Retroinguinal (Bogros) space: is bound by the transversalis fascia anteriorly, the peritoneum posteriorly and the fascia iliacus laterally. 
  • The inferior epigastric vessels: these vessels penetrate the superior layer of the transversalis fascia as it originates from the external iliac vessels. They run in the matrix between the two layers and then penetrates the superficial layer of the transversalis fascia at the level of the linea arcuata and runs into the rectus sheath.

Peritoneum

Parietal and visceral peritoneum

  • Parietal peritoneum (or fascia): this layer is a thin serous membrane acting as a balloon which lines the abdomen and into which the organs are pressed into from the outside. 
  • Visceral peritoneum (or layer): this layer lines the organs. It is known as the visceral peritoneum in the abdomen, pleura in the thorax (Gallaudet, 1931) and pericardium around the heart.
  • Between these parietal and visceral layers is a closed sac with a potential space. This space is called the peritoneal cavity in the abdomen, the pleural space in the thorax and pericardial cavity in the chest.

The parietal and visceral peritoneum are continuous at:

  • Sides and anterior surface of the ascending and descending colon.
  • Falciform ligament.
  • Lateral margin and part of the anterior surface of the left kidney.
  • Toldt's fascia: visceral peritoneum of the mesocolon fuses with the parietal peritoneum of the retroperitoneum.
  • Retroperitoneal segments of the bowel: most of the duodenum, ascending colon, descending colon and rectum.
  • Intraperitoneal bowel loops suspended by the mesentery: Loop one (abdominal oesphagus, stomach and D1). Loop two (duodenojejunal junction, jejuneum, ileum and usually the caecum). Loop three (transverse colon). Loop four: sigmoid colon and occassionally the descending colon).

In the region of the aorta and inferior vena cava the parietal peritoneum is continuous with the mesentery of the small intestine.

Where the visceral peritoneum encloses or suspends organs within the peritoneal cavity, the peritoneum and its related connective tissue forms peritoneal ligaments, omenta and mesenteries.

Peritoneal ligaments

Peritoneal ligaments are formed by fused double layers of peritoneum.

Gastrohepatic ligament: lesser omentum. Stomach: lesser curvature --> Liver: fissure for ligamentum venosum

Hepatoduodenal ligament: free margin of lesser omentum. Liver: porta hepatis --> D1 and D2: flexure between D1 and D2.

Gastrosplenic ligament: left lateral extension of the greater omentum and lateral boundary of the lesser sac. Stomach: greater curvature --> Spleen. 

Splenorenal (lienorenal) ligament: left kidney --> spleen. Surrounds the pancreatic tail and extends to the left anterior pararenal space.

Gastrocolic ligament: greater omentum. Stomach: greater curvature --> transverse colon.

Transverse mesocolon & sigmoid mesocolon: the mesocolon attaches the colon to the posterior abdominal and pelvic wall. Refer mesenteries.

Falciform ligament: separates the liver into the right and left lobes. Peritoneum behind the right rectus abdominis and diaphragm --> Liver: courses cranially along the anterior surface of the liver, blending into the hepatic peritoneal covering and then carries on posterosuperiorly to become the anterior portion of the left and right coronary. Contains the ligament teres (round ligament).

Coronary and triangular ligaments: Liver --> diaphragm: inferior surface. Bare area* of the liver is delineated by the coronary ligament centrally (anteriorly and posteriorly) and the right and left triangular ligaments laterally.

* Bare area of Liver: the cranial aspect of the liver is a convex area along the diaphragmatic surface. It is devoid of any ligamentous attachments or peritoneum. This bare area of the liver is attached to the diaphragm by flimsy fibroareolar tissue.

Ligamentum teres (round ligament): a remnant of the obliterated umbilical vein (ductus venosus). Liver: umbilical fissure --> umbilicus.

Phrenicocolic ligament: left lateral extension of the root of the transverse mesocolon. Diaphragm: opposite left r10 & r11 --> Transverse-descending colon: left (splenic) colic flexure. Passes below the spleen acting as a suspensory ligament of the spleen.

Duodenocolic ligament: right colon --> duodenum.

Mesenteries

The mesenteries are a double fold of peritoneum that attaches the intestines to the posterior abdominal wall. The mesenteries are classified as the mesentery of the small intestine, the mesentery proper, and the mesentery of the large intestine, the (mescolon.

Mesentery of the small intestine (mesentery) proper

The mesentery of the small intestine is a large and broad fan-shaped mesentery. It extends from the D/J junction (just to the left of L2) to the I/C junction (by the right SIJ) and then attaches to the posterior abdominal wall. 

Mesentery of the large intestine (mesocolon)

  • Mesoappendix: appendix --> back of the lower end of the mesentery close to the I/C junction.
  • Transverse mesocolon: transverse colon --> posterior abdominal wall. Connects to the pancreas, duodenum and greater omentum.
  • Sigmoid mesocolon: sigmoid colon --> pelvic wall. Forms an inverted 'V' attachment. The apex of the 'V' is where the division of the left iliac artery. The base of the right limb descends to median plane to the level of S3. The left limb descends medial to the left psoas major.

Sometimes the ascending and descending colon is attached to the posterior abdominal wall by the ascending and descending mesocolon. However, it is more common for the peritoneum to only cover the front and sides of the ascending and descending colon.

References

Transversalis, endoabdominal, endothoracic fascia: who's who? (2006). Skandalakis PN, Zoras O, Skandalakis JE, Mirilas P.

A description of the planes of fascia of the human body, with special reference to the fascia of the abdomen, pelvis and perineum (1931). Gallaudet B

Intertransversalis fascia approach in urologic laparoscopic operations (2012). Li G, Qian YBai HSong ZHong BJia JShi BZhang X.

THE PELVIC FLOOR—CONSIDERATIONS REGARDING ITS ANATOMY AND MECHANICS (1927). A. W. Meyer

ABDOMINOPELVIC FASCIAE (1950). MARK A. HAYES

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