Clinical aspect of abdomen

 

Abdomen


Surface markings and an
atomy

Regions of abdomen 1 hypochrondriac 2 lumbar  (flank) 3 paraumbilical 4 Iliac (iliac fossa) 5 suprapubic (hypogastric) 6 epigastric 8 transpyloric plane (L1) 9 subcostal plane 10 transtubercular plane (L5)

1 External oblique muscle of abdomen

 

Surface markings of abdominal organs

Organ

Surface marking

Spleen

9th 10th and 11th  on the left

Liver

From up of 10th rib to below the nipple. Not usually palpable below costal margin

Kidney

Upper pole is deep to 12th rib. Right kidney lies 2.5cm lower than left

Aorta

Terminates at level of iliac crest which is about L4

Pancreas

Neck lies at the level of transpyloric plane

Gall-bladder

Lies at tip of 9th costal cartilage where the lateral border of rectus abdominis cuts the costal margin

 

Anterior abdominal wall

This is the gateway to the abdominal cavity anteriorly. It exposes the true intraperitoneal structures such as the small intestine, stomach, distal duodenum, transverse colon and sigmoid colon

It is provided with the following layers

1. Skin

2. Superficial fascia

3. THERE IS NO DEEP FASCIA

4. Layer of muscles which are arranged in three strata

a.  External oblique muscle of abdomen

b.  Internal oblique muscle of abdomen

c.  Transversus abdominis

The three layers correspond to the three layers of muscles in the intercostal spaces which are the external intercostal, internal intercostals and innermost intercostals muscles

5. Transversalis fascia

6. Parietal peritoneum

The skin of the anterior abdominal wall is lax. It is distensible also to accommodate the ever increasing abdominal cavity. It has Langer’s lines running transversely and incision made on those lines (e.g. Pfannenstiel) heals with minimum of scar tissue formation.

Superficial fascia:

Superficial fascia of the anterior abdominal wall is divided into two and this is best seen below the umbilicus. It has no deep fascia.

  • Superficial Camper’s fascia is fatty. It contains loose areolar tissue.

  • Deeper Scarpa's fascia is membranous. It extends to the perineum as the Colles fascia, and it is attached to the fascia lata of the anterior aspect of thigh, to the dartos  muscle of scrotum, to the sides of the pubic bones, and to the suspensory ligament of penis or clitoris.

The layers of muscles are separated by a rectus sheath which contains the rectus abdominis. The sheath is made up of the aponeurosis of the abdominal muscles. Hence we have the aponeuroses of external oblique muscle of abdomen, internal oblique muscle of abdomen and transverses abdominis.

External oblique muscle of abdomen

This muscle has an extensive origin from the external surfaces of the lower 8 ribs as digitations. It then runs downwards and forwards like the external intercostals muscles to reach the insertion at the linea alba. The linea alba is the white line which separates the two sides of the abdominal musculature and provides the insertion of all the aponeurosis of the abdominal muscles.

The external oblique has three free borders. |

Superior free border is formed at the anterior aspects of the 5th 6th and 7th costal cartilages.

Lumbar free border which forms part of the boundaries of the lumbar triangle.

Inferior free border is formed by the inguinal ligament which is just the inward rolling of the external oblique aponeurosis. This aponeurosis is formed at the lateral border of the rectus sheath at a point called the linea semilunaris.

The following are also points of insertion of the external oblique muscle and aponeurosis

1. Anterior superior iliac spine

2. Pubic tubercle

The above two will form the attachments of the inguinal ligament

IT is also attached to the anterior 2/3 of the outer lip of the iliac crest.

Internal oblique muscle of abdomen

This muscle takes its origin from the following parts

1. Anterior 2/3 of the intermediate lip of iliac crest

2. Lateral 2/3 of the inguinal ligament

3. Conjoint lamellae of thoracolumbar fascia.

It then runs upwards and forwards as the internal intercostals muscle. It then gains its attachment (insertion) to the linea alba by its aponeurosis and also to the costal margin.

Its lower fibers also gain insertion together with the transversus abdominis, to the conjoint tendon

Transversus abdominis

 This is the innermost layer. It runs from the following parts

1. From costal margin

2. From the innermost lip of the iliac crest at its anterior ˝

3. From the lateral 1/2 of inguinal ligament

4. Fascia covering the iliacus muscle

5.  Conjoint lamellae of the thoracolumbar fascia

From these extensive origin, the fibers run into the linea alba after helping to form the posterior wall of the rectus sheath.

Some fibers gain attachment to the conjoint tendon with the internal oblique.

Rectus abdominis

The rectus abdominis takes its origin from the front of the body of the body of pubis. It then runs a straight course to reach the anterior surfaces of the 5th, 6th and 7th costal cartilages where it is attached.

It has tendinous intersections which are prominent in the muscular individual

Pyramidalis

This muscle takes origin form the superior aspect of symphysis pubis and is inserted into the linea alba. It is small pyramidal shaped muscles and is not present in all individuals.

 

Nerve supply to muscles

T7-T12 spinal nerves and L1 nerve

But the pyramidalis has a special supply from T12 nerve- subcostal nerve.

Blood supply from lumbar arteries and anterior intercostal arteries

Venous drainage is also from the lumbar veins and special veins which form caput medusae pattern around the umbilicus. A prominent vein is the thoraco-epigastric vein. Anterior abdominal wall veins distend in portal hypertension forming the characteristic caput medusae.

Rectus sheath

This is the collection of the aponeurosis of the anterior abdominal wall muscle

  • The anterior wall is formed by the external oblique aponeurosis and also

  • The anterior lamella of the internal oblique aponeurosis

  • Posterior wall of the sheath is formed by the transversus abdominis aponeurosis and the posterior lamella of the internal oblique aponeurosis. The posterior wall of the rectus sheath disappears at the midpoint between the umbilicus and symphysis pubis so that all aponeurosis below this point run anteriorly to form the anterior wall of rectus sheath. The point of departure of rectus sheath posteriorly is called the arcuate line of Douglas. Below this point there is no posterior wall of rectus. The rectus abdominis muscles lie directly on the transversalis fascia. Hence we have the various walls of the rectus sheath as follows

1. Above the costal margin- we have the posterior wall formed by the 5-7th costal cartilages, anterior surfaces. It has only external oblique aponeurosis as its anterior wall

2. Below the costal margin, we have the regular sheath with the external oblique aponeurosis and internal oblique anterior lamella. The posterior wall is formed by  the transversus abdominis and the posterior lamella of the internal oblique.

3. Below the arcuate line- there is no posterior wall of rectus sheath.

 

Inguinal canal

This canal is small one running for about 4cm from the superficial (external) inguinal ring to the deep inguinal ring

It has the following boundaries.

Floor- this is made up of the inguinal ligament. This ligament is the inward rolling externally of the aponeurosis of the external oblique muscle.

Anterior wall. This is made up of the skin, superficial fasciae of Camper's and Scarpa's. Then the external oblique aponeurosis and finally the internal oblique at its lateral 1/3.

Roof is formed by the conjoint muscle of the internal oblque and transversus abdominis muscles. They run form their attachments to the inguinal ligament (lat 1/3 for transversus abdominis, lat ˝ for internal oblique muscle).

Posterior wall is formed medially by the conjoint tendon of the internal oblique and transversus abdominis as they run from the roof to the posterior wall. They form an arch which interconnects the anterior to the roof and to the posterior walls. Laterally the posterior wall is formed by the transversalis fascia.

Medial wall is formed by lacunar ligament

Content. For the ease of description we say the content is mainly spermatic and ilioguinal nerve in the male and round ligament of uterus and ilioinguinal nerve in the female.

If we however follow the rule of three we come up with the following

Content is the spermatic cord. It has 3 coverings, 3 arteries, 3 nerves and 3 others

 

3 coverings:

1. External spermatic fascia . This is derived from the external or superficial inguinal ring.

2. Internal spermatic fascia. This is derived from transversalis fascia. It is the most internal of the coverings.

3. Cremasteric muscle and fascia, which are derived from the internal oblique muscle in the inguinal canal. It is the intermediate covering.

 

3 arteries

1. Testicular artery

2. Cremasteric artery

3. Artery of vas deferens

 

3 Nerves

1. Genital branch of genitofemoral nerve

2. Ilioinguinal nerve

3. Autonomic nerves (Sympathetic fibers)

 

3 others

1.Pampiniform plexus of veins which become the testicular vein or ovarian vein at the external inguinal ring

2. Lymphatic

3. Fat and ductus (vas) deferens

 

Hernia

A hernia is an abnormal protrusion through a normal or abnormal space or opening. In the case of the inguinal hernia, it is an abnormal protrusion through the normal inguinal canal opening. It may be congenital and if so , it may extend through the embryological processus vaginalis into the scrotal sac forming the so called congenital inguino-scrotal hernia.

The inguinal canal is formed as  an oblique opening through the muscles of the anterior abdominal wall. It extends from the superficial inguinal ring (external oblique aponeurosis) to the deep inguinal ring (transversalis fascia). It is about 4cm long.  The hernia is usually a viscus, such as small or large intestine, urinary bladder, appendix, omentum etc. It passes through  the deep inguinal ring acquiring the similar covering of internal spermatic fascia. It also acquires the covering of cremasteric fascia in the inguinal canal. In order to separate it therefore from the  spermatic cord, the line of cleavage with  the above fasciae must be sought for. It may extend from the deep inguinal ring to the superficial inguinal ring, in which case it is called the indirect or oblique hernia. If it enters through the posterior wall made up of conjoint tendon (medially) and transversalis fascia (laterally), it is called a direct hernia.

A hernia is repaired by removing the hernial sac after the reduction of the hernia and then reconstructing the inguinal canal using stitches that reduce its size.

Other types of hernia exist in the anterior abdominal wall. All anterior abdominal wall hernias are said to be external hernias as opposed to the internal hernias which occur in the peritoneal and other cavities of the body.

 

Other external hernia includes

  • Femoral hernia

  • Interstitial hernia (passes through the muscle fibers )

  • Epigastric hernias – through linea alba above the umbilicus

  • Paraumbical hernia

  • Umbilical hernia

  • Lumbar hernia (found a the lumbar triangle)

.Blood supply to the anterior abdominal wall

  • Intercostal vessels

  • Internal thoracic artery

  • Musculophrenic artery

  • Lumbar arteries

Oblique hernia

Direct hernia

  1. More frequent (80-90%)

  2. Patient is usually young

  3. Hernia is usually unilateral

  4. The bulging of the hernia is piriform (elongated)

  5. Hernia can attain a large size

  6. Hernia may reach the scrotum because it passes through the deep ring, traverses the inguinal canal and comes out through the superficial ring.

  7. Hernia is reduced in a direction upwards, laterally and backwards (i.e. in the reverse directions of its descent).

  8. Reduce the hernia and close the deep ring with the thumb. Ask the patient to cough. Hernia cannot bulge out and its impulse can be felt by the thumb

  9. The hernial sac lies in front of the spermatic cord.

  10. The hernial sac lies in front of the spermatic cord

  11. The neck of the hernial sac is lateral to the inferior epigastric vessels

  12. Hernia can be strangulated at the deep inguinal ring

  13. Coverings as previously described

  1. Less frequent (10-20%)

  2. Patient is usually over 40 years. The abdominal wall gets weak at old age

  3. Hernia is usually bilateral

  4. The bulging of the hernia is globular

  5. Hernia rarely attains a large size

  6. Hernia does not descend in to the scrotum because it lies behind the fascia transversalis of the posterior wall of inguinal canal

  7. Hernia is reduced in a directly backward direction

  8. Reduce the hernia and close the deep ring with the thumb. Ask patient to cough. Hernia bulges out medial to the position of the deep ring.

  9. The hernial sac lies behind the spermatic cord

  10. The neck of the hernial sac is medial to the inferior directions of its descent.

  11. Hernia is rarely strangulated

  12. Coverings as previously described.

 

From Mahran Z El-Din MN El-Eishi H Surgical, surface and radiological Anatomy. Cairo: University Book House, 1974, p 15

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