The Abdomen

Success is not the key to happiness. Happiness is the key to success. If you love what you are doing, you will be successful.Albert Schweitzer

Idara C. Eshiet

WINDSOR UNIVERSITY SCHOOL OF MEDICINE

Abdomen

• The abdomen is the part of the trunk between the thorax and the pelvis

Boundaries of abdomen

• Superiorly: The inferior thoracic aperture forms the superior opening to the abdomen, and is closed by the diaphragm.

• Inferiorly: the deep abdominal wall is continuous with the pelvic wall at the pelvic inlet.

Boundaries of abdomen

• Anteriorly: anteriorly, a segmented muscle (the rectus abdominis) on each side spans the distance between the inferior thoracic wall and the pelvis

• Laterally: lateral parts of the abdominal wall are predominantly formed by three layers of muscles

• Posteriorly: vertebral column, the quadratus lumborum, psoas major, and iliacus muscles

Surface landmarks and regions of the anterior abdominal wall

Topographical divisions of the abdomen are used to describe the location of abdominal organs and the pain associated with abdominal problems.

The two schemes most often used are: 1.A four-quadrant pattern2. A nine-region organizational description.

Four-quadrant pattern

• Transverse Transumbilical plane, passing through the umbilicus (and the intervertebral [IV] disc between the L3 and L4 vertebrae)

• Vertical median plane passing longitudinally through the body, dividing it into right and left halves to form four quadrants-the right upper, left upper, right lower, and left lower quadrants

Using abdominal quadrants to locate major viscera

• Liver and gallbladder are in the right upper quadrant.

• Stomach and spleen are in the left upper quadrant

• Cecum and appendix are in the right lower quadrant

• Descending colon and sigmoid colon are in the left lower quadrant.

• A common surface projection of the appendix is McBurney's point which is one-third of the way up along a line from the right anterior superior iliac spine to the umbilicus.

Nine-region organizational pattern

• The nine regions are delineated by four planes two sagittal (vertical) and two transverse

(horizontal) planes.1. Midclavicular planes that pass from the

midpoint of the clavicles (approximately 9 cm from the midline) to the midinguinal points.

2. Subcostal plane and transtubercular plane3. Or Transpyloric plane and interspinous plane

Horizontal Lines of division:

• Subcostal plane: plane passing through the inferior border of 10th rib

• Transtubercular plane: The line traversing the iliac tubercle and the body of the L5 vertebra.

• Transpyloric plane: Passes through lower border of L1 or the tip on 9th costal cartilage and the following structures are located in this plane.

• Bulb (Duodenum1),Pancreas Body and Tail, Kidney, Gall-Bladder, Liver, Pylorus of the Stomach, Duodenum and Spleen

• Interspinous plane: passes through the easily palpated ASIS of each side .

Defining surface regions to which pain from the gut is referred

• Pain from the abdominal part of the foregut is referred to the epigastric region, pain from the midgut is referred to the umbilical region, and pain from the hindgut is referred to the pubic region.

Abdomen

• 1. The Abdominal Wall• 2. The Abdominal Cavity

The Abdominal Wall

• 1. Structure of the Anterior Abdominal Wall• 2. Muscles of the Anterior Abdominal Wall• 3. Rectus Sheath• 4. Nerve Supply of Anterior Abdominal Wall Muscles• 5. Arteries of the Anterior Abdominal Wall• 6. Veins of the Anterior Abdominal Wall• 7. Lymph Drainage of the Anterior Abdominal Wall

LAYERS of ABDOMINAL WALL

• Skin• Superficial fascia

Fatty layer (Camper’s)Membranous layer

(Scarpa’s)

• Muscles & their associated deep fascias

• Transversalis fascia• Extraperitoneal fascia• Parietal peritoneum

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Superficial fascia

• Below the umbilicus, it forms two layers: a superficial fatty layer and a deeper membranous layer.

Superficial fatty layer of superficial fascia (Camper's fascia)

• Contains fat and varies in thickness.

• It is continuous over the inguinal ligament with the superficial fascia of the thigh and with a similar layer in the perineum.

• Continues over the penis and, after losing its fat and fusing with the deeper layer of superficial fascia.

• Continues into the scrotum where it forms a specialized fascial layer containing smooth muscle fibers (the dartos fascia)

Liposuction

Deeper membranous layer of superficial fascia (Scarpa's fascia)

• Is thin and membranous, and contains little or no fat.

• Inferiorly, it fuses with the deep fascia of the thigh (the fascia lata).

• It continues into the anterior part of the perineum where it is referred to as the superficial perineal fascia (Colles fascia).

Deep Fascia

• The deep fascia in the anterior abdominal wall is merely a thin layer of connective tissue covering the muscles; it lies immediately deep to the membranous layer of superficial fascia.

8 /10/ 12 what are they ?

• At T-8 level Inferior vena cava pierces

the diaphragm in the central tendinosus to get into the thoracic cavity

• At T-10 level the Esophagus pierce the

diaphragm

• At T-12 level the aorta descends into

the abdominal cavity

Anterolateral muscles

• There are five (bilaterally paired) muscles in the anterolateral abdominal wall : three flat muscles and two vertical muscles.

• Three flat muscles whose fibers begin posterolaterally, pass anteriorly, and are replaced by an aponeurosis as the muscle continues towards the midline-the external oblique, internal oblique, and transversus abdominis muscles.

• The two vertical muscles of the anterolateral abdominal wall, contained within the rectus sheath, are the rectus abdominis and pyramidalis.

External Oblique

• N. supply: Lower six thoracic nerves and iliohypogastric and ilioinguinal nerves (L1)

• Action :Supports abdominal contents; compresses abdominal contents; assists in flexing and rotation of trunk; assists in forced expiration, micturition, defecation, parturition, and vomiting

Internal oblique

• Action : Same as Ext.oblique

• N. supply: Lower six thoracic nerves and iliohypogastric and ilioinguinal nerves (L1)

Transversus abdominis

Action :Compresses abdominal contents

N. supply: Lower six thoracic nerves and iliohypogastric and ilioinguinal nerves (L1)

Associated ligaments

• The lower border of the external oblique aponeurosis forms the inguinal ligament on each side.

• lacunar ligament is a crescent-shaped extension of fibers at the medial end of the inguinal ligament that pass backward to attach to the pecten pubis on the superior ramus of the pubic bone .

• Additional fibers extend from the lacunar ligament along the pecten pubis of the pelvic brim to form the pectineal (Cooper's) ligament.

Transversalis fascia

Each of the three flat muscles is covered on its anterior and posterior surfaces by a layer of investing abdominal fascia. In general, these layers are unremarkable except for the layer deep to the transversus abdominis muscle (the transversalis fascia), which is better developed.

Rectus abdominis

• Action :Compresses abdominal contents and flexes vertebral column; accessory muscle of expiration

• N. supply: Lower six thoracic nerves

Pyramidalis (if present)

• Origin : Anterior surface of pubis • Insertion :Linea alba

• N. supply:12th thoracic nerve

• Action :Tenses the linea alba

Rectus sheath

• The rectus abdominis and pyramidalis muscles are enclosed in an aponeurotic tendinous sheath (the rectus sheath) formed by a unique layering of the aponeuroses of the external and internal oblique, and transversus abdominis muscles

Organization of the rectus sheath

A. Transverse section through the upper ¾ of the rectus sheath

B. Transverse section through the lower ¼ of the rectus sheath

Upper ¾ of the rectus sheath

The anterior wall of the rectus sheath consists of the aponeurosis of the

external oblique & half of the

aponeurosis of the internal oblique

Upper ¾ of the rectus sheath Cont’d

The posterior wall of the rectus sheath consists ofThe other half of the

aponeurosis of the internal oblique

& aponeurosis of the transversus abdominis

Lower 1/4 of the rectus sheath

• At a point midway between the umbilicus & the pubic symphysis, all the aponeuroses

move anterior to the rectus muscle.

• That is the beginning of the lower ¼ of the rectus abdominis muscle

Lower 1/4 of the rectus sheath Cont’d

• The anterior wall of the sheath consists of the aponeuroses of the

external oblique, internal oblique, and transversus abdominis m.

• There is no posterior wall at the lower ¼ of the rectus sheath

Extraperitoneal Fat

• The extraperitoneal fat is a thin layer of connective tissue that contains a variable amount of fat and lies between the fascia transversalis and the parietal peritoneum

Parietal Peritoneum

• The walls of the abdomen are lined with parietal peritoneum .

• This is a thin serous membrane and is continuous below with the parietal peritoneum lining the pelvis

OMENTA, MESENTERIES, & LIGAMENTS

• Throughout the peritoneal cavity numerous peritoneal folds (omenta, mesenteries, ligaments) connect organs to each other or to the abdominal wall.

• The Omenta consist of 2 layers of peritoneum, which pass from the stomach & the 1rst

part of the duodenum to other viscera.

• The Mesenteries are peritoneal folds that attach viscera to the posterior abdominal wall

• The ligaments consist of 2 layers of peritoneum that connect 2 organs to each other or

attach an organ to the body wall

GREATER OMENTUM

• Is a large, apron-like, peritoneal fold that attaches to the greater curvature of the stomach & the 1rst part of the duodenum.

• It is also called the abdominal policeman

GREATER OMENTUM Cont’d.

• The greater omentum is attached to:

1. The greater curvature of the stomach

2. The 1rst portion of the duodenum

3. The diaphragm4. The spleen5. The transverse colon

LESSER OMENTUM

• It is a 2 layered peritoneal omentum

• It extends from the lesser

curvature of the stomach & the 1rst part of the duodenum

to the inferior surface of the liver

LESSER OMENTUM Cont’d.

• The lesser omentum is attached to:

1. The lesser curvature of the stomach

2. The 1rst portion of the duodenum

3. The liver

THE STOMACH

• Fundus• Cardia

Cardial notch

• Body• Pylorus

Pyloric antrumPyloric canalPyloric sphincter

• Greater curvature• Lesser curvature

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GC

LC

LARGE INTESTINE (the Colon)

THE LIVER (anterior vs. posterior view)

PANCREAS vs. SPLEEN

THE KIDNEYS (Right vs. Left)

References

• Clinically oriented anatomy keith L. Moore, Arthur F. Daley, Anne M. Agur 6th Edition

• Google images