ABDOMINAL WALL EXAM 2

Anterior Abdominal Wall

Describe the umbilical ring/folds and its structure

Umbilical Ring:

A natural opening in the linea alba where the umbilical cord once entered.

The umbilical ring is a natural opening in the linea alba that allows the umbilical cord to pass during fetal life; after birth it closes to form the umbilicus, but in portal hypertension the umbilical vein may reopen, causing caput medusae.

"Ring → Cord → Scar."

• Ring = Opening

• Cord = Passes through before birth

• Scar = Belly button after birth

Describe the structure of the superficial layers of the abdominal wall:

—Camper’s fascia-

• fatty superficial layer (most superficial layer)

• Camper's fascia is the most superficial, fatty layer of the anterior abdominal wall that provides cushioning, stores fat, and forms the pannus.

—Scarpa’s fascia

• Scarpa's fascia is the deep, dense fibrous layer of the superficial fascia that provides structural support to the abdominal wall and is important for surgical closure, wound healing, and limiting the spread of fluid.

—Colles’ fascia

• Colles' fascia is the strong membranous continuation of Scarpa's fascia into the perineum, where it supports superficial tissues

"CSC = Cushion → Support → Continue"

• Camper's = Cushion (fat)

• Scarpa's = Support (dense fibrous layer)

• Colles' = Continue (Scarpa's continues into the perineum)

Identify the following abdominal wall muscles, innervation and the corresponding actions:

External oblique: The most superficial

Action:

○Flexion of the trunk - when both sides contract

○Rotation of the trunk to the OTHER side - when one sides contract

■For example, the right external oblique helps rotate the trunk to the left.

○Compression and Structural Support

Both sides contract (bilateral): ➜ Flexes the trunk (bends you forward, like a sit-up)

• One side contracts (unilateral): ➜ Rotates the trunk to the opposite side (contralateral rotation)

  • Right external oblique → rotates trunk left

  • Left external oblique → rotates trunk right

• Compresses the abdominal contents

  • Supports abdominal organs

  • Increases intra-abdominal pressure (coughing, sneezing, vomiting, defecation, childbirth)

Innervation:

Motor:

• Intercostal nerves (T7–T11)

• Subcostal nerve (T12)

Sensory:

• Iliohypogastric nerve (L1)

"External FOP 7-11 Open 12, Last is L1."

• ✅ F = Flexes trunk

• ✅ O = Opposite rotation

• ✅ P = Pressure (compresses abdomen)

Innervation:

• ✅ 7–11 = Intercostal nerves

• ✅ 12 = Subcostal nerve

• ✅ L1 = Iliohypogastric nerve

Internal oblique: Deep in the external oblique

ACTION:

○Flexion and Rotation of the Trunk:

■Flexion of the trunk - when both sides contract

■Rotation of the trunk to the SAME side - when one sides contract

This contrast with the external oblique is a favorite anatomy exam concept:

• External = Opposite

• Internal = Same

●Right internal oblique helps rotate the trunk to the right.

○Compression and Structural Support

Innervation:

• T7–T11 = Intercostal

• T12 = Subcostal

• L1 = Iliohypogastric

• L1 = Ilioinguinal

○Intercostal nerves, subcostal nerve, iliohypogastric nerve, ilioinguinal nerve

Transverse Abdominis: Deepest of the abdominal muscle

Action:

Compression the abdominal viscera - essential for activities like coughing, sneezing, vomiting, and childbirth.

-The transversus abdominis is the deepest abdominal muscle; it compresses the abdominal contents, increases intra-abdominal pressure, stabilizes the core

Innervation: ○Intercostal nerves, subcostal nerve, iliohypogastric nerve, ilioinguinal nerve.

• T7–T11 = Intercostal nerves

• T12 = Subcostal nerve

• L1 = Iliohypogastric nerve

• L1 = Ilioinguinal nerve

Rectus Abdominis: “Six-pack”

Action:

○Primary muscle for Flexion of the Trunk

○Helps flex the lumbar vertebrae, contributing to movements like curling the lower back.

○Compression of Abdominal Viscera.

○Stabilization and Control of Pelvic Tilt

• Main muscle used to bend the body forward.

• Example: Sit-ups or crunches.

Innervation: ○Intercostal nerves (T7-T11), subcostal nerve (T12)

Pyramidalis:

The pyramidalis is a small, triangular muscle located anterior to the lower part of the rectus abdominis within the rectus sheath.

ACTION:

• Tenses the linea alba (tightens the midline tendon of the abdominal wall).

• Helps stabilize the lower anterior abdominal wall.

• Does not significantly flex the trunk because it is a very small muscle.

INERVATION: Subcostal nerve (T12)

Describe the deep fascial layers:

Transversalis fascia:

a thin fibrous layer of the endoabdominal fascia that lines the deep surface of the transversus abdominis, separates the abdominal muscles from the peritoneum, supports the abdominal wall, and forms the deep inguinal ring.

Peritoneum

• Parietal (outer) = Wall = Sharp pain

• Visceral (inner) = Viscera (organs) = Vague pain

Transversalis Fascia

• Thin aponeurotic layer of endoabdominal fascia

• Lines the inner surface of the transversus abdominis

• Separates muscle from the peritoneum

Parietal peritoneum:

Description

• More superficial

• Lines the abdominopelvic wall

Innervation

• Somatic nerves

  • Intercostal nerves

  • Phrenic nerve

Pain Characteristics

The slide describes pain from the parietal peritoneum as:

• Sharp

• Intense

• Well localized

It also carries sensation for:

• Pressure

• Pain

• Heat

• Cold

Visceral peritoneum:

Description

• Deeper layer

• Covers the intraperitoneal organs

• Also known as the serosa

Innervation

• Autonomic nerves

Pain Characteristics

Pain is described as:

• Dull

• Crampy

• Poorly localized

Clinical Correlation

The PowerPoint explains appendicitis pain:

• Initially: dull ache near the belly button (visceral pain)

• Later: becomes sharp, stabbing pain in the lower right abdomen once inflammation reaches the parietal peritoneum

1. Identify the vascular supply of the anterior abdominal wall

   1. Superior epigastric artery

A. Superior Epigastric Artery

Blood Supply

• Supplies the superior portion of the anterior abdominal wall

• Venous return drains the superior portion of the anterior abdominal wall

Course

• Runs along the rectus abdominis muscle

Origin

• Branches off the internal thoracic artery

Inferior epigastric artery:

B. Inferior Epigastric Artery

Blood Supply

• Supplies the inferior portion of the abdominal wall

• Venous return drains the inferior portion of the abdominal wall

Course

• Runs along the rectus abdominis muscle

Origin

• Branches off the external iliac artery

• Feature	Inferior Epigastric Artery
  Supplies	Inferior portion of the abdominal wall
  Course	Runs along the rectus abdominis muscle
  Origin	External iliac artery

Identify the location and innervations of the anterior abdominal nerves

Iliohypogastric nerve:

A. Iliohypogastric Nerve

General Information

• Listed as one of the anterior abdominal nerves

• Covered further in the Posterior Abdominal Wall Lecture

Location

The nerve:

• Passes around the iliac crest

• Travels between the internal oblique and transversus abdominis muscles

Sensory Innervation

Provides sensory innervation to:

• Skin of the upper lateral thigh

• Skin over the pubic symphysis

• Lower abdomen

Ilioinguinal nerve:

B. Ilioinguinal Nerve

General Information

• Listed as one of the anterior abdominal nerves

• Covered further in the Posterior Abdominal Wall Lecture

Location

The nerve:

• Follows the same path as the iliohypogastric nerve

• Passes through the inguinal canal

• Exits through the superficial inguinal ring

Sensory Innervation

Provides sensory innervation to:

• Upper medial thigh

• Root of the penis and scrotum (males)

• Mons pubis and labia majora (females)

Clinical Correlation

The PowerPoint states:

The ilioinguinal nerve may become entrapped following:

• Abdominal surgery

• Groin surgery

• Hernia repair

• Laparoscopic surgery

This may result in:

• Pain

• Tingling

• Hypoesthesia in the areas it innervates

  ---

Identify the boundaries, structures, and contents of the inguinal canal

Inguinal Canal

Definition

The inguinal canal is:

• A 4 cm long oblique passage

• Acts as a pathway through the lower abdomen

Anterior superior iliac spine (pelvis):

1. Anterior Superior Iliac Spine (ASIS)

According to the slides:

• The deep inguinal ring is located halfway between the ASIS and the pubic symphysis.

Pubic tubercle (pelvis)

2. Pubic Tubercle

According to the slides:

• The superficial inguinal ring is located superior and lateral to the pubic tubercle.

Inguinal ligament:

3. Inguinal Ligament

The inguinal ligament is listed as one of the important anatomical landmarks for the inguinal canal in the objectives. It is also identified as an origin for the internal oblique and transversus abdominis muscles.

Superficial:

C. Superficial (External) Inguinal Ring

Description

The superficial inguinal ring is:

• An opening in the external oblique aponeurosis

• Located superior and lateral to the pubic tubercle

Deep inguinal rings:

B. Deep (Internal) Inguinal Ring

Description

The deep inguinal ring is:

• An opening in the transversalis fascia

• Located lateral to the inferior epigastric vessels

• An important landmark for:

  • Surgical anatomy

  • Board examinations

• Located halfway between the ASIS and the pubic symphysis

D. Contents of the Inguinal Canal

According to the PowerPoint, the inguinal canal contains:

Nerves

• Ilioinguinal nerve

• Genital branch of the genitofemoral nerve

Lymphatics

• Lymphatic vessels

Male Contents

• Spermatic cord

• Vas deferens (ductus deferens)

• Testicular artery

• Cremasteric artery

• Artery to the vas deferens

• Pampiniform plexus (becomes the testicular vein)

• Fascial layers

Female Contents

• Round ligament of the uterus

Contents Summary Table

Clinical Correlation

Inguinal Hernias

According to the slides:

An inguinal hernia occurs when:

• Abdominal contents (such as intestine or fat)

• Protrude through a weak spot in the abdominal wall.

Indirect Inguinal Hernia

The PowerPoint states that an indirect inguinal hernia:

• Follows the pathway of the inguinal canal

• Passes through:

  • Deep inguinal ring

  • Superficial inguinal ring

• Is the most common hernia in males and females.

Direct Inguinal Hernia

According to the slides:

• Protrudes directly through a weakened area of the transversalis fascia

• Occurs within Hesselbach's triangle.

PA School Exam Pearls (From the Slides Only)

• The inguinal canal is a 4 cm oblique passage through the lower abdomen.

• The deep inguinal ring is an opening in the transversalis fascia, located lateral to the inferior epigastric vesselsand halfway between the ASIS and pubic symphysis.

• The superficial inguinal ring is an opening in the external oblique aponeurosis, located superior and lateral to the pubic tubercle.

• The inguinal canal contains the ilioinguinal nerve, genital branch of the genitofemoral nerve, lymphatic vessels, the spermatic cord (male), and the round ligament of the uterus (female).

• Indirect inguinal hernias pass through both inguinal rings along the canal, while direct inguinal herniasprotrude through a weakened area of the transversalis fascia within Hesselbach's triangle.