📚 Question Bank

The bronchopulmonary segments are not drained by an independent branch of the pulmonary vein.

The tributaries of the pulmonary vein tend to pass intersegmentally between and around the margins of segments.

A bronchopulmonary segment is the area of lung supplied by a segmental bronchus and its accompanying pulmonary artery branch and can be resected surgically. It is the largest division of a lobe.

The right principal bronchus (not the right lung) is wider, shorter (2.5 cm), and more vertical than the left. The right inferior lobar bronchus is the continuation of the bronchus intermedius which is in the continuation of the right principal bronchus. These differences explain why inhaled foreign bodies enter the right principal bronchus more often than the left.

The left principal bronchus is narrower, longer (5 cm) and less vertical than the right principal bronchus.

The bronchial artery supplies the lungs up to the respiratory bronchiole.

Bronchial arteries are derived from the descending thoracic aorta either directly or indirectly. They travel and branch with the bronchi, and terminate around the level of the respiratory bronchioles.

Pulmonary arteries alone perfuse the further distal pathways including the alveolar ducts and the alveoli.

The pattern of subcutaneous venous circulation depicted in the image can be seen in cases of inferior vena caval obstruction.

The level of the umbilicus is a watershed area for venous and lymphatic circulation. The systemic veins anastomose with tributaries of portal veins at the umbilicus. Normally, venous blood and lymphatics flow upwards above the plane of the umbilicus and downwards below this plane.

Disease

Inferior vena cava obstructio n

Superior vena cava obstructi on

Pattern of blood flow in anter ior abdominal wall veins

Completely upwards Completely downwards

Disease Pattern of blood flow in anter ior abdominal wall veins

Portal hypertension Radiating away from the um bilicus like a star (caput-med usae)

The image shows a midline incision used for emergency laparotomy. Transversus abdominis muscle is not incised in this approach.

Layers of the abdomen pierced in the midline approach (from superficial to deep):

• Skin
• Superficial fascia (Campers and Scarpa)
• Linea alba
• Transversalis fascia
• Extraperitoneal fat
• Parietal peritoneum

There are no muscles pierced in this approach.

Layers of the abdomen pierced in the flanks (from superficial to deep):

• Skin
• Superficial fascia (Campers and Scarpa)
• External oblique
• Internal oblique
• Transversus abdominis
• Transversalis fascia
• Extraperitoneal fat
• Parietal peritoneum

These layers are shown in the image below:

Clinical Note: Umbilical and epigastric hernias can happen due to a congenital or acquired defect in the linea alba such as a midline abdominal incision.

The given image shows lateral flexion of the trunk being performed, which is done by the ipsilateral external oblique (EO) and internal oblique (IO) muscles.

The anterior abdominal wall comprises of 4 muscles:

• External oblique
• Internal oblique
• Transversus abdominis
• Rectus abdominis

Muscles involved in movements of the trunk include:

Action

Forward flexion of trunk (lu mbar spine)

Lateral flexion of the trunk Rotation of trunk

Tensing the linea alba

Pulling the testes towards the superficial inguinal ring

Muscles involved

Rectus abdominis and bilater al IO and EO

Ipsilateral IO and EO

Ipsilateral IO and contralater al EO

Pyramidalis Cremaster

The local anesthetic is injected between the internal oblique (marked as 2) and transversus abdominis (marked as 3) muscles in the anterior abdominal wall. This is because the neurovascular plane of the abdominal wall lies between these two muscles.

The plane between the internal oblique and transversus abdominis contains:

• Lower 6 thoracic nerves (T7-12)
• Iliohypogastric nerves
• Posterior intercostal and subcostal vessels
• Anastomosis between superior and inferior epigastric arteries

The transversus abdominis plane (TAP) block is a regional anesthetic technique used for abdominal surgeries like open cholecystectomy, open appendicectomy, and hernia surgery. It is also used for postoperative analgesia after these surgeries.

The given image represents a transverse section through the rectus sheath below the arcuate line. The arcuate line is located midway between the umbilicus and pubic symphysis.

The rectus sheath is formed from the aponeuroses of all three lateral abdominal muscles i.e. external oblique, internal oblique, and transversus abdominis. Each aponeurosis is bilaminar having 2 leaves.

Rectus sheath above the arcuate line:

• Anterior layer is composed of both leaves of the aponeurosis of the external oblique and the anterior leaf of the aponeurosis of the internal oblique.
• Posterior layer is composed of the posterior leaf of the aponeurosis of the internal oblique and both leaves of the aponeurosis of transversus abdominis.

Rectus sheath below the arcuate line

• Anterior layer is formed by the aponeurosis of all three muscles - external oblique, internal oblique, and transversus abdominis.
• Posterior layer is deficient and the rectus abdominis muscle lies directly on the fascia transversalis.

In the rectus sheath, the superior epigastric artery anastomoses with the inferior epigastric artery, a branch of the external iliac artery.

The superior epigastric artery is a branch of the internal thoracic artery. They anastomose in the rectus sheath above the level of the umbilicus.

The image given below shows the anastomosis between the superior and inferior epigastric artery in the rectus sheath.

The structure marked in the image is pyramidalis, which is supplied by the subcostal nerve

(ventral ramus of T12).

The pyramidalis is a triangle-shaped muscle that runs within the rectus sheath. The base is attached to the anterosuperior margin of the pubis and to the ligamentous fibres in front of the symphysis. The apex is attached to the linea alba.

It gets its nerve supply from the terminal branches of the subcostal nerve (the ventral ramus of T12). In some cases, it may be innervated wholly or partly by fibres from L1 travelling in the subcostal or ilioinguinal nerves.

The external oblique is present only in the anterior wall of the inguinal canal.

Internal oblique is present in the anterior wall in the lateral one-third (as muscular fibers), roof

(as arched fibers), and posterior wall (as part of the conjoint tendon) of the inguinal canal. Transversus abdominis is present as part of the roof and posterior wall (as the conjoint tendon)

Internal spermatic fascia is a derivative of fascia transversalis.

External spermatic fascia is derived from external oblique aponeurosis. The cremasteric fascia is derived from internal oblique.

Option B: The ilioinguinal nerve does not enter the inguinal canal at the deep inguinal ring. It enters the inguinal canal by piercing its posterior wall.

Option C: The cremasteric artery is a branch of the inferior epigastric artery. Option D: Indirect inguinal hernias are seen in both men and women.

In bulbar urethral injury, the medial portion of the thigh is the least likely site for the collection of urine.

The rupture of the urethra below the urogenital diaphragm will result in extravasation of urine into the superficial perineal pouch, penis and scrotum in males and labia majora in females, and the anterior abdominal wall.

The superficial fascia of the abdomen is divided below the umbilicus into a superficial fatty layer (fascia of Camper) and a deep membranous layer (fascia of Scarpa). Scarpa's fascia is continuous with the membranous layer of the superficial perineal fascia (Colles' fascia).

Colles' fascia is attached to fascia lata (the deep fascia of the thigh) along the Holden's line that extends from the pubic tubercle laterally for 8 cm. Extravasated fluid cannot pass into the medial thigh below Holden's line due to the firm attachment of Colles' fascia to the fascia lata.

The structure marked 3 is the conjoint tendon. It is formed from the lower fibers of the internal oblique and the lower part of the aponeurosis of the transversus abdominis. It is attached to the pubic crest and extends to a variable extent along the pectineal line.

Transversus Abdominis muscle:

Origin - from the internal surface of 7th-12th costal cartilages, thoracolumbar fascia, iliac crest, connective tissue deep to lateral third of inguinal ligament.

Insertion - at the linea alba with the aponeurosis of internal oblique, pubic crest, and pecten pubis via the conjoint tendon.

The structures marked in red are the tubercles of the iliac crest. An imaginary line passing through them forms the trans-tubercular plane which lies at the upper border of L5.

The abdomen is divided into 9 regions based on the following:

• Two transverse planes:
• Subcostal plane which is indicated by a line that joins the lowest point of the costal margin on each side. It corresponds to the level of 10th costal cartilage and lower border of second lumbar vertebra(L2) or upper border of third lumbar vertebra (L3)
• Trans-tubercular plane is indicated by a line that joins the tubercles of the iliac crests. It corresponds to the level of fifth lumbar vertebra (L5).
• Two vertical planes on both sides:
• Right and left lateral planes passing from mid-clavicular point to the mid-inguinal point.

The structure marked in the image is the transpyloric plane which is present at L1 level. The origin of the celiac trunk (T12) and lower limit of the spinal cord of a newborn (L3) are not present at this level.

The transpyloric plane (Addison's plane) passes midway between the suprasternal notch of the manubrium and the upper border of the pubic symphysis. This approximately corresponds to midway between the xiphisternal joint and the umbilicus. Posteriorly, this plane passes through the lower half of the body of the first lumbar vertebra (lower border of L1).

Structures present in the transpyloric plane:

Organs

Pylorus of stomach

D1 part of the duodenum Duodenojejunal flexure

Fundus of the gallbladder

Hilum of the left kidney (righ t kidney is slightly lower)

Neurovascular structures

Origin of the superior mesent eric artery

Origin of the renal artery

Origin of the portal vein (beh ind the neck of the pancreas)

Lower limit of the spinal cord in adults

Cisterna chyli

The structure marked in the image is the fundus of the gallbladder. It lies at the level of L1 in the transpyloric plane.

The tip of the ninth costal cartilage in the transpyloric plane, near the junction of the linea semilunaris with the costal margin is used to identify the fundus of the gall bladder.

The transpyloric plane is an imaginary plane that lies midway between the suprasternal notch and the upper border of the pubic symphysis. Posteriorly, this plane intersects the lower half of the body of the first lumbar vertebra. Anteriorly, it intersects the costal margin at the ninth costal cartilage.

The pancreas is a retroperitoneal structure. All the other structures listed are intraperitoneal. Pain originating from retroperitoneal organs are likely to be referred to the back.

Relationship of viscera to the peritoneum:

Intraperitoneal

Stomach

Jejunum and ilium

Transverse and sigmoid colo n

Liver and gallbladder Spleen

Retroperitoneal

Esophagus (abdominal) D2 and D3 duodenum Pancreas

Kidneys, ureters, and adrenal gland

Abdominal aorta and inferior vena cava

Celiac plexus

Partially covered in the perit oneum(considered as retrope ritoneal)

Ascending colon Descending colon Rectum

The root of the mesentery is approximately 15 cm long. It is crossed by the right ureter and right psoas major and it crosses the midline.

The root of the mesentery is the attachment of the mesentery of the small intestine to the posterior abdominal wall. It runs diagonally from the duodenojejunal flexure on the left side of the L2 vertebral body to the right sacroiliac joint. The length of intestinal attachment of the mesentery measures approximately 5 to 6 meters (same as the length of the small intestine) and it has a breadth (from the root to the intestinal border) of 20 cm.

Structures crossed by the root of the mesentery include:

• Third part of the duodenum
• Abdominal aorta
• Inferior vena cava
• Right ureter
• Right psoas major

Contents of the mesentery include:

• Superior mesenteric vessels (jejunal and ileal branches)
• Nerves related to the superior mesenteric plexus
• Lymphatics and regional lymph nodes
• Connective tissue and fat

The mesorectum is excised in total mesorectal excision. It contains the superior rectal vein.

The rectum has no mesentery attached to it. However, it is surrounded by fat which is enclosed within a fascial envelope known as the mesorectum, which contains:

• Superior rectal artery and its branches
• Superior rectal vein and its tributaries
• Lymphatic vessels and nodes

Anterolaterally, branches of the inferior hypogastric plexus and middle rectal vessels enter the mesorectum covered in a layer of fascia which is known as the lateral rectal ligament.

Total mesrectal excision (TME) is a standard procedure done for rectal cancer. It includes resection of tumor along with the surrounding fatty tissues, blood vessels and lympatics present in the mesorectum.

The structure marked in the image is the medial umbilical fold. It overlies the obliterated umbilical artery.

The peritoneum of the lower anterior abdominal wall is raised into five folds that diverge as they descend from the umbilicus. These include:

Umbilical folds Median umbilical fold

Medial umbilical folds

Lateral umbilical folds

Features

Single, present in the midline Extends from the umbilicus t o the apex of the bladderRem nant of the urachus

Two in numberExtends from the internal iliac artery to the umbilicusOverlies the obliter ated umbilical artery

Two in numberOverlies the i nferior epigastric vessels

Paraduodenal recess contains the inferior mesenteric vein in its right free margin.

The fourth part of the duodenum and the duodenojejunal junction has several folds of peritoneum that give rise to many named recesses. They are probably formed during development due

to minor aberrations of duodenal rotation and fixation. The duodenal recesses include:

Recess

Superior duodenal recess

Inferior duodenal recess

Para-duodenal recess

Retroduodenal recess

Mesenterico-parietal recess

Duodenojejunal recess

Location

Directly left of D4Opposite L 2 vertebraBehind the duoden ojejunal fold

Left of D4 (sometimes behin d)Opposite L3 vertebraBehin d the duodenomesocolic fold

Slightly left and behind D4Be hind falciform fold of periton eum

Behind D3 and D4Has a wide orifice, with duodeno-parieta l folds on either side

Below D3Forms a pocket in t he right upper part of mesent ery

Below pancreasBetween DJ j unction and root of transvers e mesocolon

Vascular relations

Inferior mesenteric vein is di rectly behind the lateral edge of the recess

Passes in front of ascending branch of left colic artery and inferior mesenteric vein

Right free edge contains infer ior mesentric vein and ascen ding branch of left colic arter y

Lies in front of the abdomina l aorta

Has a large, left facing orifice behind a fold raised by the s uperior mesenteric artery

Left of the abdominal aorta

The most dependent part of the peritoneal cavity in the supine position is the right subhepatic space (hepatorenal pouch of Morison). The intra-abdominal fluid gets collected in this space in the supine position.

It lies between the inferior surface of the right lobe of the liver and the upper pole of the right kidney.

The boundaries of the hepatorenal pouch are as follows:

• Superiorly - inferior layer of the coronary ligament.
• Inferomedially - hepatic flexure, transverse mesocolon, second part of the duodenum, and part of the head of the pancreas.
• Laterally - right lateral abdominal wall
• Posteriorly - anterior surface of the upper pole of the right kidney
• Note: The most dependent part of the peritoneal cavity in erect posture:
• In males - rectovesical pouch
• In females - rectouterine pouch.

Paraduodenal recess contains the inferior mesenteric vein in its right free margin.

The fourth part of the duodenum and the duodenojejunal junction has several folds of peritoneum that give rise to many named recesses. They are probably formed during development due

to minor aberrations of duodenal rotation and fixation. The duodenal recesses include:

Recess

Superior duodenal recess

Inferior duodenal recess

Para-duodenal recess

Retroduodenal recess

Mesenterico-parietal recess

Duodenojejunal recess

Location

Directly left of D4Opposite L 2 vertebraBehind the duoden ojejunal fold

Left of D4 (sometimes behin d)Opposite L3 vertebraBehin d the duodenomesocolic fold

Slightly left and behind D4Be hind falciform fold of periton eum

Behind D3 and D4Has a wide orifice, with duodeno-parieta l folds on either side

Below D3Forms a pocket in t he right upper part of mesent ery

Below pancreasBetween DJ j unction and root of transvers e mesocolon

Vascular relations

Inferior mesenteric vein is di rectly behind the lateral edge of the recess

Passes in front of ascending branch of left colic artery and inferior mesenteric vein

Right free edge contains infer ior mesentric vein and ascen ding branch of left colic arter y

Lies in front of the abdomina l aorta

Has a large, left facing orifice behind a fold raised by the s uperior mesenteric artery

Left of the abdominal aorta

The inferior pancreaticoduodenal artery does not contribute to the blood supply of the stomach. It is a branch of the superior mesenteric artery. It supplies the duodenum (second and third parts) and the pancreas (head and uncinate process).

The arterial supply of the stomach is contributed exclusively by the celiac trunk through its branches:

• Left gastric artery - supplies the lesser curvature of the stomach
• Splenic artery:
• Short gastric arteries - fundus
• Left gastroepiploic artery - greater curvature
• Common hepatic artery:
• Right gastric artery - lesser curvature
• Gastroduodenal artery - right gastroepiploic artery arises from this and supplies the greater curvature of the stomach.

Clinical note: The presence of an abnormal, tortuous artery in the submucosa of the lesser curvature is called the Dieulafoy's lesion. As it is superficial, it is more vulnerable to rupture causing significant haemorrhage.