Abdominal Wall, Anatomy Exam 3

Carroll University Path-A 2026

What nerve innervates the anterolateral walls?

Ventral rami of T7-L1

Where does the nerve for the anterolateral walls travel?

IAO and TA

What does the ventral rami of T7-L1 innervate in the anterolateral walls?

Skin

Abdominal wall

Peritoneum (lining)

L1 in the anterolateral walls is represented by what 2 nerves?

Ilio hypogastric

Ilio inguinal

What is the posterior muscle of the abdominal wall?

quadratus lumborum

What is the action of the quadratus lumborum?

Fix the 12th rib during an inhale trunk flexion

What is the nerve innervation of the quadratus lumborum?

lumbar plexes

What are the muscles of the anterior abdominal wall (5)?

External Abdominal Oblique (EAO)

Internal Abdominal Oblique (IAO)

Transversus Abdominus (TA)

Rectus Abdominus (RA)

Pyramidalis

What is clinically significant about the IAO?

The testes descend through the inguinal canal, which push the IAO with them. The cremaster muscle is a direct extension of the IAO

What is clinically significant about the pyramidalis muscle?

It is not found in 20% of people

It also marks an incision landmark, it is the midpoint of the linea alba

What is the action of the rectus abdominus muscle?

Compress and support abdominal viscera, flex and rotate the trunk

What is the nerve innervation of the rectus abdominus?

thoracoabdominal and T12

What is the action of the EAO muscle?

Compress and support abdominal viscera, flex and rotate the trunk

What is the nerve innervation of the EAO muscle?

thoracoabdominal nerve

What is the action of the IAO muscle?

Same action EAO and RA

What is the nerve innervation of the IAO muscle?

thoracoabdominal, L1 and L2

What is the action of the TA muscle?

Same action as RA, EAO and IAO

What is the nerve innervation of the TA muscle?

Thoracoabdominal, L1

What is the action of the pyramidalis?

Draw down the linea alba

What is the nerve innervation of the pyramidalis?

Thoracoabdominal nerve

The rectus sheath is a woven aponeuroses from what 3 muscles?

EAO (anterior)

IAO (lateral)

TA (posterior)

In the fascial linings of the anterolateral abdominal wall, the superficial fascia divides into what two layers?

Fatty (outer)

Membranous (inner)

The transversalis fascia is what kind of tissue?

loose areolar tissue

The transversalis fascia is located between what structures?

muscle and peritoneum

The transversalis fascia contains what kind of vessels?

Blood and lymph vessels

the peritoneum is comprised of 2 layers:

Visceral

Parietal

The peritoneal cavity has potential space that is filled with what kind of fluid?

peritoneal fluid

The potential space in the peritoneal cavity is open to the exterior in what sex?

female

the peritoneum ‘folds’ or ‘reflexes’ back on itself to create what structures?

mesenteries

What is the omenta?

multiple layers of reflected peritoneum

The parietal portion of the peritoneum is innervated by what 4 nerves?

Phrenic nerve

T7-T11

T12 (subcostal)

L1-L2

What is the parietal peritoneum sensitive to?

Pain, temp, touch, pressure

What is the the nerve innervation of the visceral peritoneum?

Autonomic efferents (sensory)

What is the visceral peritoneum sensitive to?

stretch only

What structures are within the inguinal triangle?

RA (medial)

Epigastric vessels (lateral)

Inguinal ligament (inferior)

The inguinal ligament is folded inferior fibers from the EAO, which span from what?

Anterior superior iliac spine to the pubic tubercle

The inguinal canal begins and ends where?

it begins at the deep ring and ends at the superficial ring

In males, what does the inguinal canal contain?

spermatic cord, IAO (cremaster) and the EAO fascia

In females, what does the inguinal canal contain?

round ligament

What is within the VAN in the inguinal canal?

Blood vessels (artery and vein)

Ilioinguinal nerve (L1 branch)

How large is the inguinal canal?

Quarter size

What is the deep (internal) inguinal ring?

Entrance to the canal

Has outpocketing transversalis fascia

In women, what passes though the deep inguinal ring?

round ligament

In men, what passes through the deep inguinal ring?

Vas deferens

The superficial (external) inguinal ring is the:

exit to the canal

It splits the aponeurosis of EAO muscle, incomplete TA

What exits through the superficial inguinal ring in women?

Round ligament

What exits through the superficial ring in men?

spermatic cord

Intra-abdominal pressure and EAO, what is the function of these if working together?

contraction of this is used to strengthen the abdominal wall and prevent herniation, along with assists in forced breathing and facilitates vital bodily functions like lifting heavy loads, coughing, and defecation

What is the most common hernia?

Inguinal hernia

What is a hernia?

A protrusion of parietal peritoneum and abdominal viscera (intestines) through normal/abnormal opening (inguinal canal)

What is the indirect hernia?

congenital hernia

Who is most commonly affected by a congenital hernia?

males and females, but usually males

Is the congenital (indirect) or acquired (direct) hernia more common?

Congenital, affects 2/3, born with defect in the canal

What are some characteristics of a congenital hernia?

Span entire canal, enters through the deep, exit superficial ring

Who is most commonly affected by an acquired (direct) hernia?

males

What are some characteristics of the acquired (direct) hernia?

Weak abdominal wall, the anterior wall will weaken, deep ring is affected, rarely superficial

Umbilical hernias are commonly found in what population?

Newborns

Why are umbilical hernias commonly seen in newborns?

The anterior abdominal wall is weak

What causes an umbilical hernia in a newborn?

Increased pressure during cutting of umbilical cord

Acquired umbilical hernias occur in what population?

pregnant individuals and obese individuals (males and females)

What are the contents that can be found in a herniated sac?

Peritoneum and fat