ABD AND PELVIS

Boundaries of the abdomen

• Superior: Inferior thoracic aperture (closed by diaphragm)

• Inferior: Pelvic inlet

What is the circular space created by the pelvic brim and is freely continuous with pelvic cavity?

Pelvic inlet

What ribs have parts that are abdominal?

11th and 12th

What is the layer of membranes that surrounds the organs?

Peritoneum

How is the abdominal cavity devided?

Through the sacral promontory and superior aspect of the pubic symphysis

What is the name of the important vertical plane (midinguinal)?

Midclavicular

Where would you find the transtubercular plane?

Tubercle of ilium (L5 vert)

What does the abdomen assist in?

Breathing, defecation, micturition, and childbirth

Contraction of the diaphragm causes ________ of the abdominal muscles

Relaxation

Relaxation of the diaphragm causes _________ of the abdominal muscles

Contraction

What makes up the abdominal wall?

Series of overlapping muscles, tendons, and aponeurosis

This muscle’s fibers are interrupted by 1 to 4 tendinous intersections on both sides

Rectus abdominus

What are the layers of the abdominal wall from superficial to deep?

• Skin

• Superficial fascia

  • Camper’s fascia

  • Scarpa’s fascia

• Muscles and muscular fascia

• Transversalis fascia

• Extraperitoneal fat

• Parietal layer of peritoneum

What layer of superficial fascia is a mix fatty tissue and loose areolar tissue?

Camper’s fascia

What superficial fascia is the deepest of the two layers?

Scarpa’s fascia

Which of the two oblique muscles have a more superficial insertion?

External oblique

What muscle?

• Origin: External surface of lower eight ribs

• Insertion: Anterior portion of iliac crest; anterior-superior iliac spine; pubic tubercle; linea alba

• Innervation: Intercostal n. (T7-T11); Subcostal nerve (T12)

External oblique

What is the subcostal nerve?

An intercostal nerve that has no rib below is so it is “subcostal”

What abdominal muscle compresses the abdomen, flexes the trunk, and is active in forced expiration?

External oblique

What muscle has the same action as the external oblique and works together with that muscle?

Internal oblique

What muscle?

• Origin: Lateral 2/3 of inguinal ligament; iliac crest; thoracolumbar fascia

• Insertion: Lower four costal cartilages; linea alba; pubic crest; pectineal line

• Innervation: Intercostal nerves (T7-T11), Subcostal nerve (T12); Iliohypogastric and ilioinguinal nerve (L1)

Internal oblique

Where does innervation from the lumbar spinal nerves begin? (What muscle?)

Internal oblique

What are the mixed nerves that stem from the L1 spinal nerve and innervate the internal oblique?

Iliohypogastric and ilioinguinal nerve

What is the blood supply of the internal oblique?

Subcostal arteries

How to the fibers of the obliques run with each other?

Somewhat perpendicular

What muscle shares the aponeurosis with the obliques near the rectus abdominis muscle?

Transverse abdominis

What muscle?

• Origin: Lateral 1/3 of the inguinal ligament; iliac crest; thoracolumbar fascia; lower 6 costal cartilages

• Insertion: Linea alba; pubic crest; pectineal line

• Upper level innervation: Intercostal nerves (T7-T11); Subcostal nerve (T12)

• Lower level innervation: Iliohypogastric and ilioinguinal nerve (L1)

Transverse abdominis

What is the blood supply of the transverse abdominis?

Subcostal arteries

What muscle compresses abdomen and depresses ribs?

Transverse abdominis

How do the fibers of the transverse abdominis run?

Transverse abdominis

What muscle?

• Origin: Pubic crest and pubic symphysis

• Insertion: Xiphoid process and costal cartilages 5-7

• Innervation: Intercostal (T7-11); Subcostal nerve (T12)

Rectus abdominis

What is the blood supply of the rectus abdominis muscle?

Inferior epigastric artery

Where would you find the inferior epigastric artery?

Midline running behind the rectus sheath

What vessel anastomoses with the superior epigastric artery to join the internal thoracic artery?

Inferior epigastric artery

What is the internal, investing layer of the fascia lining the entire abdominal wall?

Transversalis fascia

The transversalis fascia includes, but is not limited to, the internal investing fascia of what muscle?

Transversus abdominis

What is formed by the aponeuroses of the transverse abdominal and the external and internal oblique muscles?

Rectus sheath

What is the structure that occurs about ½ of the distance from the umbilicus to the pubic crest?

Arcuate line

How do the tendons of the internal oblique orient themselves with the rectus sheath above the arcuate line?

Invests the rectus abdominis

How do the tendons of the internal oblique orient themselves with the rectus sheath below the arcuate line?

Anteriorly (no posterior rectus sheath)

Below the arcuate line, what is the layer that sits posterior to the rectus abdominis muscle?

Transversalis fascia

What is the clinical significance of the site of weakness below the arcuate line?

Possible space for hernias

Where, on the abdomen, would you find this cross section?

Above arcuate line

Defects in the abdominal wall allow herniation of abdominal contents. What do these structures push through when herniating?

Fascia

When does a hernia become dangerous?

Incarcerated hernia

What is an incarcerated hernia?

Herniation cuts off blood supply → tissue dies → infection of entire abdominal cavity

What muscle?

• Origin: iliac crest and iliolumbar ligament → attaches to last lumbar vertebrae

• Insertion: last rib and transverse processes of lumbar vertebrae

• Innervation: 12th thoracic and 1st-4th ventral rami of lumbar nerves (T12, L1-L4)

Quadratus lumborum

What is the blood supply of the quadratus lumborum?

Lumbar arteries and lumbar branch of iliolumbar arteries

What muscle, when acting alone, helps with lateral flexion of the vertebral column?

Quadratus lumborum

What muscle, when acting with its counterpart, helps depress the thoracic rib cage by pulling on the 12th rib during inspiration?

Quadratus lumborum

Which muscle?

• Origin: upper 2/3 of the iliac fossa

• Insertion: base of the lesser trochanter of femur

• Innervation: femoral nerve

Iliacus

What is the blood supply of the iliacus muscle?

• Medial femoral circumflex artery

• Iliac branch of iliolumbar artery

What muscle flexes and rotates the thigh laterally?

Iliacus

What muscle?

• Origin: transverse processes of T12-L5 and the lateral aspects of the discs between them

• Insertion: on the lesser trochanter of the femur

• Innervation: lumbar plexus via anterior branches of L1-L3 branches

Psoas major

What is the blood supply of the psoas major muscle?

Lumbar branch of iliolumbar artery

What muscle runs parallel to the spinal cord, flexes the trunk, and flexion in the hip joint? (kicking a ball)

Psoas major

What muscle?

• Origin: lateral bodies of T12 and L1 vertebrae

• Insertion: pectineal line of the hip bone

• Innervation: branch of L1 spinal nerve

Psoas minor

What is the blood supply of the psoas minor muscle?

Lumbar branch of iliolumbar artery

What muscle works with the psoas major to flex the hip and is absent in up to 40% of people?

Psoas minor

What is the innervation of the skin, muscles, and paritoneum of the anterolateral abdominal wall?

• T7 → T12 spinal nerves

• L1 spinal nerve

What does the the L1 spinal nerve from the lumbar plexus give off?

• Iliohypogastric nerve

• Ilio-inguinal nerve

Where do the iliohypogastric and ilioinguinal nerves pass into the inguinal cavity?

Inguinal canal

Where does the superior epigastric artery arise from?

Internal thoracic artery

Where does the inferior epigastric artery arise from?

External iliac artery

Where does the external iliac artery arise from?

Abdominal aorta

Where do the superior and inferior epigastric artery anastamosis?

Within the rectus sheath, specifically on the posterior surface of the rectus abdominis muscle

Where would you find the T10 dermatome?

Umbilicus region

What does the ilioinguinal nerve innervate?

• Motor

  • Transversus abdominis

  • Internal oblique

• Sensory:

  • Anterior surface of scrotum and labia majora

Where would you feel liver and gallbladder visceral pain?

Right shoulder

Where would you feel pancreas and stomach visceral pain?

Epigastric area (transverse radiation)

Where would you feel small intestine visceral pain?

Umbilical area

What is the junction between anterior and abdominal wall and thigh?

Inguinal region

What region is there often weaknesses due to changes during development or through increased activity?

The inguinal region

Descent of Gonads from high into the abdomen to the pelvis via embryologic muscular-fibrous band called the ______

Gubernaculum

When does the descent of the gonads happen?

In utero

What muscles make up the external abdominal wall?

• Transversus abdominis muscle

• Internal oblique muscle

• External oblique muscle

As the gonads descend a tunnel of tissue forms from what?

The aponeurosis of the abdomen wall

In the descent of the gonads, the testicle descends through canal, eventually creating _____

Spermatic cord

In women, what does the gubernaculum become?

The round ligament of the uterus

What is the pocket of parietal peritoneum that forms anterior to the gubernaculum?

Processus vaginalis

As the testis descends, what is it surrounded by?

Fascia and muscles

What structure?

• Passage that extends downward and medial

• Created by aponeurosis of the abdominal wall

• Contains a deep and superficial ring

• Spermatic cord and round ligament of the uterus pass through

Inguinal canal

What ligament forms the inferior border of the aponeurosis of the external oblique?

Inguinal ligament

What ligament lies between the anterior superior iliac spine and the pubic tubercle?

Inguinal ligament

What muscle is the extension of the internal oblique fibers as it is pulled by the testes?

Cremaster muscle

Where would you find the deep inguinal ring?

• Midway between anterior iliac spine and pubic symphysis

• Above inguinal ligament and lateral to inferior epigastric vessels

Where would you find the superficial inguinal ring?

• The end of the inguinal canal

• Opening in the aponeurosis of the external oblique

Components of the inguinal canal

• Men: spermatic cord

• Women: round ligament and genitofemoral nerve

• ilioinguinal nerve

Components of spermatic cord

• Ductus deferens

• Testicular artery

• Pampiniform veins

• Genitofemoral nerve

Pathway of ilioinguinal nerve through inguinal canal

Enters canal by piercing internal surface of the transversus abdominis → exits through superficial inguinal ring

Where do the femoral arteries arise from?

External iliac vessels

What is an area of potential weakness and hence is a common site of a direct inguinal hernia?

Inguinal triangle

What are the borders of the inguinal (Hesselbach’s) triangle?

• Medially: linea semilunaris (lacteral edge of the rectus abdominis)

• Laterally: Inferior epigastric vessels

• Inferiorly: The inguinal ligament

What type of inguinal hernia passes through the inguinal canal?

Indirect inguinal hernia

What hernia lies lateral to the inferior epigastric vessels and is congenital and associated with the persistence of the processus vaginalis if not sealed correctly?

Indirect inguinal hernia

Pathway of indirect inguinal hernia

Deep inguinal ring → inguinal canal → superficial inguinal ring → descends into scrotum

What is this structure?

Processus vaginalis

• potential space made of parietal peritoneum

When would you see a “funnel” at the deep inguinal ring?

Indirect inguinal hernia

What hernia passes directly through abdominal wall (shortest route possible)?

Direct inguinal hernia

What hernia occurs through the posterior wall of the inguinal canal but does not descend into the scrotum?

Direct inguinal hernia