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Questions and Answers
Which of the following is NOT one of the flat muscles of the abdominal wall?
Which of the following is NOT one of the flat muscles of the abdominal wall?
What is the primary function of the external oblique muscle?
What is the primary function of the external oblique muscle?
Where do the fibers of the external oblique muscle originate?
Where do the fibers of the external oblique muscle originate?
Which layer of fascia is the membranous deep layer also known as?
Which layer of fascia is the membranous deep layer also known as?
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What defines the inguinal ligament?
What defines the inguinal ligament?
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The lacunar ligament is associated with which part of the inguinal ligament?
The lacunar ligament is associated with which part of the inguinal ligament?
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What is the main role of the abdominal wall muscles?
What is the main role of the abdominal wall muscles?
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Which of the following is NOT a characteristic of the superficial and deep layers of fascia?
Which of the following is NOT a characteristic of the superficial and deep layers of fascia?
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Which muscles are primarily engaged during full sit-ups?
Which muscles are primarily engaged during full sit-ups?
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When twisting to the right during abdominal exercises, which muscles are activated?
When twisting to the right during abdominal exercises, which muscles are activated?
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What forms the anterior wall of the rectus sheath?
What forms the anterior wall of the rectus sheath?
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Which level of dermatomes corresponds to the skin around the umbilicus?
Which level of dermatomes corresponds to the skin around the umbilicus?
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What is the deep blood supply to the abdominal area derived from?
What is the deep blood supply to the abdominal area derived from?
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What marks the transition point of the aponeuroses moving to the anterior wall of the rectus sheath?
What marks the transition point of the aponeuroses moving to the anterior wall of the rectus sheath?
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Which nerves are responsible for innervating the muscles of the abdomen?
Which nerves are responsible for innervating the muscles of the abdomen?
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Referred pain from the appendix is associated with which dermatome level?
Referred pain from the appendix is associated with which dermatome level?
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What is the insertion point of the Internal Oblique muscle?
What is the insertion point of the Internal Oblique muscle?
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Which nerve primarily innervates the Rectus Abdominis muscle?
Which nerve primarily innervates the Rectus Abdominis muscle?
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What is the action of the Transversus Abdominis muscle?
What is the action of the Transversus Abdominis muscle?
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During curl-ups, which muscle primarily engages in flexion of the torso?
During curl-ups, which muscle primarily engages in flexion of the torso?
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What fibers direction do the Internal Oblique muscles take?
What fibers direction do the Internal Oblique muscles take?
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Which of the following muscles is located deep to the Internal Oblique?
Which of the following muscles is located deep to the Internal Oblique?
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What is the origin of the Rectus Abdominis muscle?
What is the origin of the Rectus Abdominis muscle?
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Which muscle tenses the linea alba?
Which muscle tenses the linea alba?
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What structure forms the roof of the inguinal canal?
What structure forms the roof of the inguinal canal?
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Which artery is NOT one of the three arteries associated with the spermatic cord?
Which artery is NOT one of the three arteries associated with the spermatic cord?
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In which type of hernia does the bulge occur medial to the epigastric vessels?
In which type of hernia does the bulge occur medial to the epigastric vessels?
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What is the primary characteristic of an indirect inguinal hernia?
What is the primary characteristic of an indirect inguinal hernia?
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Which ligament is part of the floor of the inguinal canal?
Which ligament is part of the floor of the inguinal canal?
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Which layer does the cremasteric layer of the spermatic cord originate from?
Which layer does the cremasteric layer of the spermatic cord originate from?
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What defines a femoral hernia in relation to the pubic tubercle?
What defines a femoral hernia in relation to the pubic tubercle?
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What is the main defining feature of a hernia?
What is the main defining feature of a hernia?
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What anatomical structure is primarily responsible for the descent of the testes into the scrotum?
What anatomical structure is primarily responsible for the descent of the testes into the scrotum?
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Which layer does NOT contribute to the layers acquired by the testes during descent?
Which layer does NOT contribute to the layers acquired by the testes during descent?
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Where do the superficial lymphatics below the umbilicus drain?
Where do the superficial lymphatics below the umbilicus drain?
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The lymphatic drainage of the testis primarily follows which anatomical route?
The lymphatic drainage of the testis primarily follows which anatomical route?
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Which of the following layers is NOT considered part of the spermatic cord?
Which of the following layers is NOT considered part of the spermatic cord?
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What is the correct drainage pathway for abdominal wall deep lymphatics above the umbilicus?
What is the correct drainage pathway for abdominal wall deep lymphatics above the umbilicus?
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What anatomical layer lies directly above the testis after it descends into the scrotum?
What anatomical layer lies directly above the testis after it descends into the scrotum?
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Which structure acquires layers from the abdominal wall as the testis descends?
Which structure acquires layers from the abdominal wall as the testis descends?
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What structure constitutes the beginning and end of the inguinal ligament?
What structure constitutes the beginning and end of the inguinal ligament?
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Which nerve is primarily innervated by the internal oblique muscle?
Which nerve is primarily innervated by the internal oblique muscle?
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What is the primary action of the rectus abdominis muscle?
What is the primary action of the rectus abdominis muscle?
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What is the location of the transversalis fascia in relation to the abdominal wall?
What is the location of the transversalis fascia in relation to the abdominal wall?
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Which of the following statements regarding Hesselbach's triangle is correct?
Which of the following statements regarding Hesselbach's triangle is correct?
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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.
