Abdominal Wall Anatomy Quiz

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Questions and Answers

Which of the following is NOT one of the flat muscles of the abdominal wall?

External oblique

Internal oblique

Transverse abdominis

Pyramidalis (correct)

What is the primary function of the external oblique muscle?

Stabilize the spine

Extend the trunk

Rotate the pelvis

Compress the abdominal contents (correct)

Where do the fibers of the external oblique muscle originate?

Lumbar vertebrae

Pelvic brim

Iliac crest

Ribs 5-12 (correct)

Which layer of fascia is the membranous deep layer also known as?

Scarpa’s fascia Signup and view all the answers

What defines the inguinal ligament?

A rolled-in free lower border of the external oblique aponeurosis Signup and view all the answers

The lacunar ligament is associated with which part of the inguinal ligament?

Medial end Signup and view all the answers

What is the main role of the abdominal wall muscles?

Facilitate trunk movement and stability Signup and view all the answers

Which of the following is NOT a characteristic of the superficial and deep layers of fascia?

They contain muscles Signup and view all the answers

Which muscles are primarily engaged during full sit-ups?

Rectus femoris and iliopsoas Signup and view all the answers

When twisting to the right during abdominal exercises, which muscles are activated?

Left external oblique and right internal oblique Signup and view all the answers

What forms the anterior wall of the rectus sheath?

Aponeuroses of internal and external oblique Signup and view all the answers

Which level of dermatomes corresponds to the skin around the umbilicus?

T10 Signup and view all the answers

What is the deep blood supply to the abdominal area derived from?

Inferior epigastric vessels and deep circumflex from the external iliac Signup and view all the answers

What marks the transition point of the aponeuroses moving to the anterior wall of the rectus sheath?

Arcuate line Signup and view all the answers

Which nerves are responsible for innervating the muscles of the abdomen?

Nerves coursing between the internal oblique and transversus abdominis Signup and view all the answers

Referred pain from the appendix is associated with which dermatome level?

T10 Signup and view all the answers

What is the insertion point of the Internal Oblique muscle?

Linea alba and pubic crest Signup and view all the answers

Which nerve primarily innervates the Rectus Abdominis muscle?

Thoracoabdominal T7-11 Signup and view all the answers

What is the action of the Transversus Abdominis muscle?

Compress abdominal contents Signup and view all the answers

During curl-ups, which muscle primarily engages in flexion of the torso?

Rectus Abdominis Signup and view all the answers

What fibers direction do the Internal Oblique muscles take?

Superomedial Signup and view all the answers

Which of the following muscles is located deep to the Internal Oblique?

Transversus Abdominis Signup and view all the answers

What is the origin of the Rectus Abdominis muscle?

Pubic crest, tubercle & symphysis Signup and view all the answers

Which muscle tenses the linea alba?

Pyramidalis Signup and view all the answers

What structure forms the roof of the inguinal canal?

Arching fibers of transversus abdominis and internal oblique Signup and view all the answers

Which artery is NOT one of the three arteries associated with the spermatic cord?

Inferior mesenteric artery Signup and view all the answers

In which type of hernia does the bulge occur medial to the epigastric vessels?

Direct inguinal hernia Signup and view all the answers

What is the primary characteristic of an indirect inguinal hernia?

It is congenital and passes through the deep ring. Signup and view all the answers

Which ligament is part of the floor of the inguinal canal?

Inguinal ligament Signup and view all the answers

Which layer does the cremasteric layer of the spermatic cord originate from?

Internal oblique Signup and view all the answers

What defines a femoral hernia in relation to the pubic tubercle?

Neck is below and lateral to the pubic tubercle Signup and view all the answers

What is the main defining feature of a hernia?

Abnormal protrusion of an organ through a cavity defect Signup and view all the answers

What anatomical structure is primarily responsible for the descent of the testes into the scrotum?

Processus vaginalis Signup and view all the answers

Which layer does NOT contribute to the layers acquired by the testes during descent?

Transversus abdominis Signup and view all the answers

Where do the superficial lymphatics below the umbilicus drain?

Superficial inguinal nodes Signup and view all the answers

The lymphatic drainage of the testis primarily follows which anatomical route?

Para-aortic nodes at L1 Signup and view all the answers

Which of the following layers is NOT considered part of the spermatic cord?

Colle’s fascia Signup and view all the answers

What is the correct drainage pathway for abdominal wall deep lymphatics above the umbilicus?

To parasternal nodes along the internal thoracic artery Signup and view all the answers

What anatomical layer lies directly above the testis after it descends into the scrotum?

Tunica vaginalis Signup and view all the answers

Which structure acquires layers from the abdominal wall as the testis descends?

Spermatic cord Signup and view all the answers

What structure constitutes the beginning and end of the inguinal ligament?

The pubic tubercle to the anterior superior iliac spine Signup and view all the answers

Which nerve is primarily innervated by the internal oblique muscle?

Ilioinguinal nerve Signup and view all the answers

What is the primary action of the rectus abdominis muscle?

Flexion of the lumbar spine Signup and view all the answers

What is the location of the transversalis fascia in relation to the abdominal wall?

It is a deep layer beneath the abdominal muscles. Signup and view all the answers

Which of the following statements regarding Hesselbach's triangle is correct?

It is a region for direct inguinal hernias. Signup and view all the answers

Study Notes

Abdominal Wall Fascia

Composed of two layers: superficial fatty layer (Camper's fascia) and deep membranous layer (Scarpa's fascia)
Superficial vessels and nerves run between these layers

Muscles of the Abdominal Wall

5 muscles on each side
Divided into two groups: 3 flat muscles (external oblique, internal oblique, transversus abdominis) and 2 vertical muscles (rectus abdominis, pyramidalis)

Flat Muscles

Located laterally, stacked upon one another
As they pass anteriorly, they continue as aponeurosis
Act to flex, laterally flex, and rotate the trunk
Fibres run in differing directions, strengthening the abdominal wall and decreasing risk of herniation

External Oblique

Most superficial
Origin: Ribs 5-12
Insertion: Iliac crest and linea alba, fibers in inferomedial direction
Innervation: Thoracoabdominal nerves T7-T11 and subcostal nerve T12
Action: Compresses abdominal contents, flexes trunk, bends trunk to same side, turns anterior part of abdomen to opposite side.
Lower border folds on itself to form the inguinal ligament

Associated Ligaments

Inguinal ligament: Rolled-in free lower border of external oblique aponeurosis on each side
- Passes between anterior superior iliac spine (ASIS) and pubic tubercle
- Forms a crucial part of the inguinal canal
Lacunar ligament: Crescent-shaped extension of fibers at the medial end of the inguinal ligament
- Attaches to the pecten pubis
Pectineal (Cooper's) ligament: Extended fibers along the pecten pubis of the pelvic brim
Midpoint of the inguinal ligament: Halfway along the ligament, surface marking for the deep inguinal ring and femoral nerve
Mid-inguinal point: Halfway between ASIS and superior border of the pubic symphysis, surface marking for the femoral artery

Internal Oblique

Deep to the external oblique
Origin: Lateral 2/3 of inguinal ligament, iliac crest, and thoracolumbar fascia
Insertion: Linea alba, pectineal line, pubic crest, inferior border of ribs 9-12, fibers passing in a superomedial direction
Innervation: Thoracoabdominal nerves T7-T11 and subcostal nerve T12, iliohypogastric (L1) and ilioinguinal (L1)
Action: Compresses abdominal contents, flexes trunk, bends trunk and turns anterior part of abdomen to same side

Transversus Abdominis

Deep to the internal oblique
Origin: Iliac crest, lateral 1/3 of inguinal ligament, thoracolumbar fascia, and ribs 7-12
Insertion: Linea alba, pubic crest, and pectineal line, fibers pass transversely
Innervation: Thoracoabdominal nerves T7-T11 and subcostal nerve T12, iliohypogastric (L1) and ilioinguinal (L1)
Action: Compresses abdominal contents

Vertical Muscles

Rectus Abdominis

Origin: Pubic crest, tubercle & symphysis
Insertion: Costal cartilage of ribs 5-7, xiphoid process
Innervation: Thoracoabdominal nerves T7-T11, subcostal T12
Action: Compresses abdomen contents, flexes vertebral column, tenses abdominal wall

Pyramidalis

Origin: Pubic symphysis and pubic bone
Insertion: Linea alba
Innervation: Subcostal nerve (T12)
Action: Tenses the linea alba

Curl-ups/Sit-ups

Rectus abdominis muscles are engaged during flexion of the torso with assistance from abdominal obliques
Hip flexors (rectus femoris and iliopsoas muscles) are engaged during full sit-ups
Abdominal oblique muscles are more active when a rotation is added to the flexion:
- Left external abdominal oblique and right internal abdominal oblique are activated when twisting to the right
- Opposite combination occurs when twisting to the left

Rectus Sheath

Formed by aponeuroses of the 3 flat muscles
Anterior wall: External oblique aponeurosis and half of internal oblique
Posterior wall: Half internal oblique aponeurosis and transversus abdominis aponeurosis
Above the arcuate line (midway between umbilicus and pubic symphysis), all aponeuroses move to the anterior wall of the rectus sheath
Below the arcuate line, the posterior wall is missing, and rectus abdominis is in direct contact with transversalis fascia

Nerve Supply

Motor and sensory
Nerves course between internal oblique and transversus abdominis muscles
Innervate the muscles and terminate by supplying the skin

Dermatomes

T7: Skin on xiphoid process
T10: Skin around the umbilicus
L1: Skin on the inguinal ligament

Blood Supply

Deep supply:
- Superior epigastric vessel (from internal thoracic artery)
- Inferior epigastric vessels and deep circumflex (from external iliac)
- Musculophrenic artery: 10th and 11th intercostal arteries, and subcostal artery (from the internal thoracic)

Inguinal Canal

Floor: Inguinal ligament, lacunar ligament medially
Anterior wall: Aponeurosis of external oblique, internal oblique laterally
Roof: Arching fibers of transversus abdominis and internal oblique
Posterior wall: Transversalis fascia, conjoint tendon medially

Spermatic Cord

3 layers: Internal spermatic fascia (transversalis fascia), cremasteric layer (internal oblique), external spermatic fascia (external oblique)
3 arteries: Testicular (from aorta at L2), cremasteric (from inferior epigastric), artery of vas (from superior vesical)
3 nerves: Nerve to cremaster (from genitofemoral), sympathetic (deep pain sensation), ilioinguinal (separate)
3 other things: Vas deferens, pampiniform plexus of veins, lymphatics to para-aortic nodes at L2

Hernia

Abnormal protrusion of an organ, tissue, or structure through a defect in the cavity that normally contains it
Groin hernias: Common, 75% of all hernias, 25% of males and 2% of females have inguinal hernias in their lifetime
Inguinal hernia: Neck is above and medial to the pubic tubercle
Femoral hernia: Neck is below and lateral to the pubic tubercle

Inguinal Hernia - Indirect

Through inguinal canal
Congenital
Through the deep ring, along the inguinal canal, superficial ring to the scrotum
Can be controlled at the deep ring if reduced
Bulge occurs lateral to the epigastric vessels as the abdominal content passes through the deep ring

Inguinal Hernia - Direct

Weakness in transversalis fascia and superficial ring
Bulge occurs medial to the epigastric vessels (Hesselbach's triangle)
Acquired due to heavy lifting, constipation, sports (e.g. rugby)

Descent of Testes

Processus vaginalis projects into the labioscrotal swelling and usually disappears except the distal part
Testis acquires layers from the abdominal wall as it moves into the scrotum

Scrotum Anatomy

Layers

Skin
Colle's fascia and dartos muscle
External spermatic fascia
Cremasteric fascia and muscle
Internal spermatic fascia
Extraperitoneal fat
Tunica vaginalis

Lymphatic Drainage

Superficial Lymphatics of the Abdomen

Above the umbilicus: Drain to the axillary nodes
Below the umbilicus: Drain to the superficial inguinal nodes

Deep Lymphatics of the Abdomen

Follow deep arteries:
- Parasternal nodes along the internal thoracic artery
- Lumbar nodes along the abdominal aorta
- External iliac nodes along the external iliac artery
Testis drains to para-aortic nodes at L1
Skin of the scrotum drains into inguinal nodes

Pelvic Inlet

Defined by the pelvic brim, which separates the pelvic cavity from the abdominal cavity

External Oblique

Origin: Outer surfaces of the ribs 5-12
Insertion: Iliac crest, linea alba, and the pubic tubercle
Fibre direction: Downward, forward, and medially
Innervation: Thoracoabdominal nerves (T7-T11) and subcostal nerve (T12)
Action: Flexion, lateral rotation, and compression of the abdomen
Lower border forms: Inguinal ligament

Inguinal Ligament

Beginning: Anterior superior iliac spine
End: Pubic tubercle
Forms: The lower border of the external oblique and the superior boundary of the femoral canal
Made from: Thickened lower edge of the external oblique aponeurosis

Mid-Inguinal Point

Location: Midway between the anterior superior iliac spine and the pubic symphysis
Surface marking for: Deep inguinal ring and femoral nerve

Lacunar Ligament

Shape: Triangular
Location: Medial to the inguinal ligament
Attaches: To the iliopubic eminence

Pectineal Ligament

Location: Runs along the pectineal line (superior ramus of the pubis)
Attaches: To the iliopubic eminence and the Cooper's ligament

Internal Oblique

Origin: Thoracolumbar fascia, iliac crest, and lateral two-thirds of the inguinal ligament
Insertion: Linea alba, costal margin (10th-12th ribs), and the pubic crest
Fiber direction: Upward, forward, and medially
Innervation: Thoracoabdominal nerves (T7-T11) and subcostal nerve (T12)
Action: Flexion, lateral rotation, and compression of the abdomen

Transversus Abdominis

Origin: Inner surfaces of ribs 7-12, thoracolumbar fascia, iliac crest, and the lateral third of the inguinal ligament
Insertion: Linea alba, pubic crest, and the pectineal line
Fiber direction: Horizontally
Innervation: Thoracoabdominal nerves (T7-T11) and subcostal nerve (T12)
Action: Compression of the abdomen

Rectus Abdominis

Origin: Pubic symphysis and pubic crest
Insertion: Costal cartilages of ribs 5-7 and the xiphoid process
Fiber direction: Vertically
Innervation: Thoracoabdominal nerves (T7-T11) and subcostal nerve (T12)
Action: Flexion of the trunk and compression of the abdomen

Pyrimidalis

Origin: Pubic crest
Insertion: Linea alba
Innervation: Subcostal nerve (T12)
Action: Tenses the linea alba

Rectus Sheath

Anterior wall above arcuate line: External oblique aponeurosis and anterior lamina of the internal oblique aponeurosis
Posterior wall above arcuate line: Posterior lamina of the internal oblique aponeurosis and the transversus abdominis aponeurosis
Anterior wall below arcuate line: External oblique aponeurosis and anterior lamina of the internal oblique aponeurosis
Posterior wall below arcuate line: Transversalis fascia

Transversalis Fascia

Location: Deep to the transversus abdominis muscle
Nerve location: Nerves run between the transversalis fascia and internal oblique muscle
Nerves involved: Ilioinguinal, iliohypogastric, genitofemoral, lateral femoral cutaneous, and subcostal

Dermatomes of the Abdomen

T7: Xiphoid process
T8: Below xiphoid process
T9: Umbilicus
T10: Pubic symphysis
T11: Scrotum/labia majora
T12: Inguinal region
L1: Anterior thigh and knee

Vessels of the Abdomen

Deep supply: Superior and inferior epigastric arteries, deep circumflex iliac artery, and lumbar arteries
Superficial supply: Superficial epigastric artery, superficial circumflex iliac artery, and superficial external iliac artery

Inguinal Canal

Length: 4-5 cm
Floor: Inguinal ligament
Anterior wall: Aponeurosis of external oblique
Roof: Arch formed by the internal oblique and transverse abdominus
Posterior wall: Transversalis fascia and conjoint tendon (formed by the aponeurosis of the internal oblique and transversus abdominis that fuse)
Beginning & end: Deep inguinal ring (lateral opening, formed by the transversalis fascia) and superficial inguinal ring (medial opening, formed by the external oblique aponeurosis)
Contents:
- Male: Spermatic cord
- Female: Round ligament of the uterus
- Both sexes: Ilioinguinal nerve

Spermatic Cord

Rule of 3: 3 arteries, 3 veins, 3 nerves, 3 layers, and other things
Layers: External spermatic fascia, cremaster muscle, internal spermatic fascia
Arteries: Testicular artery, cremasteric artery, artery of the vas deferens
Nerves: Genitofemoral nerve, ilioinguinal nerve, cremasteric nerve
Other things: Pampiniform plexus, vas deferens, lymphatic vessels

Inguinal Hernia

Direct: Protrudes directly through the posterior wall of the inguinal canal, medial to the inferior epigastric vessels
Indirect: Protrudes through the deep inguinal ring, lateral to the inferior epigastric vessels

Femoral Hernia

Protrudes through the femoral canal, inferior and lateral to the inguinal ligament

Hesselbach's Triangle

Bounded by the inguinal ligament, inferior epigastric vessels, and the lateral border of the rectus abdominis muscle

Layers of Abdominal Wall & Corresponding Spermatic Cord

Abdominal Wall Layer	Spermatic Cord Layer
Skin	Skin
Superficial fascia	Superficial fascia (Dartos muscle)
External oblique aponeurosis	External spermatic fascia
Internal oblique muscle	Cremaster muscle
Internal oblique aponeurosis	Internal spermatic fascia
Transversus abdominis muscle	-
Transversalis fascia	-
Peritoneum	Peritoneum

Superficial Lymphatics

Above umbilicus: Drain to axillary lymph nodes
Below umbilicus: Drain to superficial inguinal lymph nodes

Deep Lymphatics

Drain to the internal iliac lymph nodes

Testicular Drainage

Drains to the lumbar (para-aortic) lymph nodes

Scrotum Skin Drainage

Drains to the superficial inguinal lymph nodes

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Description

Test your knowledge on the anatomy of the abdominal wall, including its fascia, muscles, and their functions. This quiz covers the layers of fascia, types of muscles, and their innervations. Feel confident in your understanding of this vital area of human anatomy.