Abdominal Region

Question 1

What is the function of the abdominal wall?

Answer 1

Made up of sheets of muscle and their corresponding sheets of tendon. Hold the abdominal viscera within the abdominal cavity and play an important part in rotating the body, in respiration, coughing, sneezing, micturition, defecation and childbirth by contracting to increase intra-abdominal pressure.

Question 2

What is a hernia?

Answer 2

The abnormal exit of tissue or an organ, such as the bowel, through the wall of the cavity in which it normally resides.

Question 3

What is the rectus abdominis muscle?

Answer 3

A pair of vertical muscles. Originates from the crest of the pubis, before inserting into the xiphoid process of the sternum and the costal cartilage of ribs 5-7. Acts to assist the flat muscles in compressing the abdominal viscera, stabilise the pelvis during walking, and depress the ribs.

Question 4

What is the external oblique muscle?

Answer 4

Most superficial flat muscle in the abdominal wall. Its fibres run inferomedially. Originates from ribs 5-12, and inserts into the iliac crest and pubic tubercle. Acts to contralaterally rotate the torso. Innervated by Thoracoabdominal nerves (T7-T11) and subcostal nerve (T12).

Question 5

What is the internal oblique muscle?

Answer 5

Deep to external oblique, runs superiomedially. Originates from the inguinal ligament, iliac crest and lumbodorsal fascia, and inserts into ribs 10-12.Bilateral contraction compresses the abdomen, while unilateral contraction ipsilaterally rotates the torso.Thoracoabdominal nerves (T7-T11), subcostal nerve (T12) and branches of the lumbar plexus.

Question 6

What is the transversus abdominis?

Answer 6

Deepest muscle. Runs transversely. Deep to this muscle runs the transversalis fascia. Originates from the inguinal ligament, costal cartilages 7-12, the iliac crest and thoracolumbar fascia. Inserts into the conjoint tendon, xiphoid process, linea alba and the pubic crest. Acts to compress the abdominal contents. Thoracoabdominal nerves (T7-T11), subcostal nerve (T12) and branches of the lumbar plexus.

Question 7

What is the inguinal ligament?

Answer 7

The lowest most extent of the external oblique muscle is ligamentous throughout its length and is attached to the anterior superior iliac spine laterally and the pubic tubercle medially.

Question 8

What is the linea alba?

Answer 8

A fibrous line that splits the rectus abdominis into two. It is visible as a vertical groove extending inferiorly from the xiphoid process.

Question 9

What makes up a six pack?

Answer 9

The Rectus Abdominis muscle is intersected by fibrous strips, known as tendinous intersections. The tendinous intersections and the linea alba give rise to the ‘six pack’ seen in individuals with a well-developed rectus abdominis. When exercised the muscle hypertrophies (becomes bigger) but the tendinous part stays the same. The result is three bulges (of muscle) between the tendons. This occurs on either side of the midline; six bulges in all.

Question 10

For anatomical division of the abdomen, what are the vertical lines?

Answer 10

he vertical line on each side extends from the mid-clavicular point to the mid-inguinal point (halfway between the anterior superior iliac spine of the pelvis and the pubic symphysis).

Question 11

For anatomical division of the abdomen, what are the horizontal lines?

Answer 11

The lower transverse line is drawn between the tubercles of the iliac crests (intertubercular plane) - L4. The upper transverse line is the subcostal (or transpyloric) plane, joining the lowest part of the costal margins on both sides (L1).

Question 12

What are the 9 anatomical regions? Label on a diagram

Answer 12

Upper: right hypochondrium, epigastic, left hypochondrium
Middle: right lumbar, umbilical, left lumbar
Lower: right flank/groin/iliac, hypogastric/suprapubic, left flank/groin/iliac

Question 13

What is McBurney’s point?

Answer 13

This point lies ⅔ of the way along a line joining the umbilicus to the right anterior superior iliac spine. It marks the usual site of the base of the appendix. It also gives a guide to the position of the caecum.

Question 14

What is the umbilicus?

Answer 14

Variable and unreliable landmarks that marks the point of insertion of the umbilical cord during embryonic life and the level of the L3 vertebra.

Question 15

How is visceral and parietal pain different?

Answer 15

Parietal: sharp pain well-localised to area
Visceral: dull achy pain poorly-localised to area

Question 16

How does referred pain of the internal organs work in the abdomen?

Answer 16

Foregut: supplied by the greater splanchnic nerve (T5-T9), referred pain in the epigastrium
Midgut: supplied by the lesser splanchnic nerve (T10-T11), referred pain in the periumbilical area
Hindguit: supplied by the least splanchnic nerve (T12), referred pain in the suprapubic area

Question 17

Where is pain felt if the peritoneum is diseased?

Answer 17

The peritoneum covering the inside of the abdominal wall has the same sensory nerve supply as the skin overlying the same area of the abdominal wall. If the disease process involves the abdominal wall, the pain is felt very precisely over that area.

Question 18

Where would pain from an inflamed diaphragm be felt?

Answer 18

Disease which inflames the diaphragm like cholecystitis (inflammation of the gall bladder) may be felt as referred pain the in C3, C4, C5 distribution. This pain is felt in the shoulder.

Question 19

Where would pain from the kidneys be felt?

Answer 19

The sensory innervation of the kidney is via the sympathetic plexus which accompanies the renal artery (T10, T11, T12), same plexus as the gonad. Pain from the kidney can be referred through the cutaneous nerves of T10, 11, 12 and the pain is often described as radiatinng from the loin to the groin. Renal pain can also be felt in the gonal area.

Question 20

Label some of the bony landmarks of the pelvis on a diagram

Answer 20

Iliac Crest
Anterior Superior Iliac Spine
Pubic tubercle
Pubic Symphysis

Question 21

Where would pain from the appendix be felt?

Answer 21

Typical history for appendicitis is a vague dull central abdominal pain which after a few hours or days moves to the right iliac fossa and changes character, from dull to sharp as the pain is felt in the skin

Question 22

Where would pain from an aortic aneurysm be felt?

Answer 22

An aortic aneurysm is an abnormal swelling of the aorta which can burst and cause sudden death. Because the aorta only extends as far as the intertubercular plane, an aortic aneurysm is only felt above this point (epigastrium down to the umbilicus).

Question 23

How is shingles a good example of a disease which presents with dermatomal effects?

Answer 23

Shingles is caused by the Herpes Zoster which becomes dormant in the sensory dorsal root ganglia and can activate when the patient becomes ill. The virus reproduces and travels down the sensory nerve fibres to the skin which it produces a very itchy rash with vesicles If the virus is in the T10 spinal nerve the rash will form as a ribbon from the T10 vertebra at the back to the umbilicus at the front (T10 dermatome).

Question 24

What is the inguinal canal?

Answer 24

A short passage that extends inferiorly and medially through the inferior part of the abdominal wall. It is superior and parallel to the inguinal ligament.

Question 25

What is the function of the inguinal canal?

Answer 25

The canal serves as a pathway by which structures can pass from the abdominal wall to the external genitalia.
In males, the inguinal canal is the pathway by which the testes leave the abdominal cavity and enter the scrotum. A fibrous cord of tissue called the gubernaculum attaches the inferior portion of the gonad to the future scrotum or labia, and guides them during their descent. In females, the ovaries move into the pelvic cavity. The gubernaculum then becomes two structures in the adult: the ovarian ligament and round ligament of uterus.

Question 26

What are the boundaries of the inguinal canal?

Answer 26

Anterior wall – aponeurosis of the external oblique, reinforced by the internal oblique muscle laterally.
Posterior wall – transversalis fascia.
Roof – transversalis fascia, internal oblique, and transversus abdominis.
Floor – inguinal ligament, thickened medially by the lacunar ligament.

Question 27

What is the deep inguinal ring?

Answer 27

The deep (internal) ring is found above the midpoint of the inguinal ligament. which is lateral to the epigastric vessels. The ring is created by the transversalis fascia, which invaginates to form a covering of the contents of the inguinal canal.

Question 28

What is the superficial inguinal ring?

Answer 28

The superficial (external) ring marks the end of the inguinal canal, and lies just superior to the pubic tubercle. It is a triangle shaped opening, formed by the evagination of the external oblique, which forms another covering of the inguinal canal contents.

Question 29

What is the conjoint ligament?

Answer 29

A structure formed from the lower part of the common aponeurosis of the internal oblique muscle and the transversus abdominis as it inserts into the crest of the pubis and pectineal line immediately behind the superficial inguinal ring.

Question 30

What are the two types of inguinal hernia?

Answer 30

Direct and indirect

Question 31

What is a direct hernia?

Answer 31

Direct inguinal hernia (20%) – Bowel enters the inguinal canal “directly” through a weakness in the posterior wall of the canal, termed Hesselbach’s triangle
They occur more commonly in older patients, often secondary to abdominal wall laxity or a significant increase in intra-abdominal pressure

Question 32

What is an indirect hernia?

Answer 32

Indirect inguinal hernia (80%) – Bowel enters the inguinal canal via the deep inguinal ring
They arise from incomplete closure of the processus vaginalis, an outpouching of peritoneum allowing for embryonic testicular descent, therefore are usually deemed congenital in origin

Question 33

What is the upper extent of the abdominal cavity?

Answer 33

Anteriorly the under surface of the diaphragm reaches the 5th intercostal space.

Question 34

Describe the nerve supply to the skin of the abdominal wall.

Answer 34

The dermatomes of the abdominal wall start at thoracic 5 in the upper epigastrium, with thoracic 10 being at the umbilicus and thoracic 12 being just above the hair bearing area in the lower suprapubic area. Each dermatome starts at the back at the level of the named vertebra; the dermatomes run downwards as they pass round the trunk to the front.

Question 35

How is the rectus sheath formed?

Answer 35

In the upper 2/3 of the abdomen the aponeurosis of the external oblique muscle passes in front of rectus abdominis and the aponeurosis of transversus abdominis passes behind. The aponeurosis of internal oblique sends fibres both in front and behind rectus abdominis. In the lower 1/3 of the abdomen all three aponeuroses pass in front of rectus abdominis.

Question 36

What is the surface marking of the aortic bifurcation?

Answer 36

The level of the umbilicus.