Muscles of the Trunk and Pelvic Floor Flashcards
List the 5 main cavities of the body.
1 - Cranial cavity.
2 - Spinal cavity.
3 - Thoracic cavity.
4 - Abdominal cavity.
5 - Pelvic cavity.
What are the superior boundaries of the abdominal cavity?
1 - Costal margins.
2 - The abdominal surface of the diaphragm.
What are the anterolateral boundaries of the abdominal cavity?
The anterolateral muscles of the abdomen.
What are the posterior boundaries of the abdominal cavity?
1 - The vertebral column.
2 - The erector spinae muscles.
3 - Quadratus lumborum.
4 - Iliopsoas.
What are the inferior boundaries of the abdominal cavity?
1 - The inguinal ligament.
2 - The arcuate line.
What is the arcuate line?
A horizontal line that demarcates the lower limit of the posterior layer of the rectus sheath.
List the 12 layers of the anterolateral abdominal wall in order from superficial to deep.
1 - Skin.
2 - Subcutaneous fat.
3 - Camper’s fascia (superficial fascia).
4 - Scarpa’s fascia (superficial fascia).
5 - External oblique.
6 - Intermediate investing fascia.
7 - Internal oblique.
8 - Deep investing fascia.
9 - Transversus abdominis.
10 - Transversalis fascia.
11 - Extraperitoneal fat.
12 - Parietal peritoneum.
What happens to the 3 muscle layers of the abdominal wall at the midline?
They fuse to form the rectus abdominis muscle.
With which muscle do the upper four slips of the external oblique muscle interdigitate?
The (costal fibres of) latissimus dorsi.
How many digitations of the external oblique muscle are there?
8.
With which muscle do the lower four slips of the external oblique muscle interdigitate?
Serratus anterior.
Where does the internal oblique lie in relation to the external oblique and transversus abdominis muscles?
It lies deep to the external oblique and superficial to the transversus abdominis.
In which direction do the fibres of the internal oblique muscle travel in relation to the fibres of the external oblique muscle?
Perpendicular.
Where does the internal oblique muscle originate?
- From the thoracolumbar fascia of the lower back.
- From the anterior 2/3 of the iliac crest (upper part of the hip bone).
- From the lateral half of the inguinal ligament.
Where is the inguinal ligament?
From the pubic tubercle to the anterior superior iliac spine.
Where is the linea alba?
It runs down the midline of the abdomen from the xiphoid process to the pubic symphysis.
Where does the internal oblique muscle insert?
- On the inferior borders of ribs 10-12.
- At the linea alba.
What is different about the internal oblique muscle in males as compared to females?
- The cremaster muscle is attached to the internal oblique muscle in males only.
- Useful when you want to raise your testicles.
Where does the external oblique originate and insert?
Origins: Along ribs 5-12.
Insertions: Into the linea alba, the pubis and the iliac crest.
Where does the transversus abdominis originate and insert?
Origins: Along ribs 7-12, the thoracolumbar fascia and the iliac crest.
Insertions: The linea alba.
What is the rectus sheath formed by and what does it contain?
- It is formed by the aponeuroses of the external oblique, internal oblique and transverse abdominis muscles.
- The aponeurotic compartment containing the rectus abdominis muscle and the pyramidalis muscle.
Where does the rectus abdominis originate and insert?
Origins: Pubic symphysis, pubic crest and pubic tubercle.
Insertions: Xiphoid process and ribs 5-7.
What are tendinous intersections?
Bands of connective tissue that traverse the rectus abdominis, separating it into its distinct muscle bellies.
What is the linea semilunaris?
The outer, most lateral line of the abs.
What layers exist above the rectus sheath?
1 - Camper’s fascia (anterior part of the superficial fascia).
2 - Scarpa’s fascia. (posterior part of the superficial fascia).
Above the costal margin, what is the anterior sheath composed of?
The aponeurosis of the external oblique only.
Describe the arrangement of the aponeuroses of the muscles of the abdominal wall below the umbilicus.
- All of the aponeuroses run in front of the rectus abdominis.
- The combination of all 3 aponeuroses forms the rectus sheath.
Describe the arrangement of the aponeuroses of the muscles of the abdominal wall at the level of the umbilicus.
- The rectus abdominis is surrounded both anteriorly and posteriorly by aponeuroses.
- The anterior sheath is formed by the aponeuroses of the external and internal oblique muscles.
- The posterior sheath is formed by the aponeuroses of the internal oblique muscle and the transverse abdominis muscle.
What is the inguinal canal?
An oblique passage through the lower part of the anterior abdominal wall.
Where is the inguinal canal?
- It lies parallel to and immediately above the inguinal ligament.
- It extends from the deep inguinal ring downward and medially to the superficial inguinal ring.
What passes through the inguinal ligament?
- In males, the spermatic cord.
- In females, the round ligament of the uterus (from the uterus to the labia).
- The ilioinguinal nerve in both sexes.
How does the inguinal canal differ between men and women?
Inguinal canals are larger in men.
How does the inguinal canal differ between newborn children and adults?
- In the newborn child, the deep ring lies almost directly posterior to the superficial ring.
- The deep ring must therefore move superiorly and laterally.
List the boundaries of the inguinal canal.
- Anterior wall: The aponeurosis of the external oblique muscle.
- Posterior wall: Transversalis fascia.
- Floor: The inguinal ligament.
- Roof: The internal oblique muscle and the transversus abdominis muscle.
- Medially: The conjoint tendon (supports the posterior wall).
What is the transversalis fascia and where is it?
- A thin aponeurotic membrane.
- Lies between the inner surface of the transversus abdominis and the parietal peritoneum.
Which of the inguinal rings are palpable?
The superficial inguinal ring only.
Give an example of a condition in which the superficial inguinal ring becomes dilated.
Athletic pubalgia.
What is the difference between a direct and indirect inguinal hernia?
- A direct inguinal hernia is a hernia in which the abdominal contents protrude through a defect in the posterior wall and emerge through the superficial ring.
- An indirect inguinal hernia is a hernia in which the abdominal contents protrude through the deep ring, through the canal and through the superficial ring.
What forms the deep inguinal ring?
It is an opening of the transversalis fascia.
What forms the superficial inguinal ring?
It is an opening of the external oblique muscle.
What is the perineum?
- The area between the anus and the scrotum or vulva.
- In terms of bony landmarks, it is between the ischial tuberosities and the pubic symphysis.
What is the pelvic diaphragm and where is it?
- A sheet of muscle covered on both surfaces by fascia.
- It closes the pelvic cavity inferiorly and assists in the support of the abdominopelvic viscera.
- It is stretched like a hammock between the pubis in front and the coccyx behind.
- It is attached along the lateral pelvic wall to a thickened band of the obturator fascia.
Which muscles compose the pelvic diaphragm?
- 2 levator ani muscles (anterior).
- 2 coccyegus muscles (posterior).
Which fasciae exist in the pelvic diaphragm?
The superior and inferior layers of pelvic fascia.
What is the perineal body?
What are its functions?
- A thickened mass of connective tissue in the centre of the inferior pelvic aperture.
- It makes the muscles of the pelvic floor sag.
- It also anchors the perineal membrane to the perineum at the midline.
- It is a site of muscle atachment.
Where are the urogenital and anal triangles?
- The inferior pelvic aperture is diamond shaped, owing to the bones of the pelvis.
- If an imaginary horizontal line is drawn such that it bisects the perineal body, the diamond is split into two triangles.
- The anterior triangle is the urogenital triangle.
- The posterior triangle is the anal triangle.
List 3 functions of the perineal membrane.
1 - Attaches perineum to the external layer of fascia above.
2 - Defines the openings of the urethra and vagina.
3 - Anchors the external genitalia to the pelvic floor.
List 4 muscles that attach to the perineal body.
1 - The urethral sphincters.
2 - The superficial transverse perineal muscle.
3 - The deep transverse perineal muscle.
4 - The bulbospongiosus muscle.
List the layers of tissue of the pelvic floor in order from superficial to deep.
1 - Perineum.
2 - Perineal membrane.
3 - Inferior layer of fascia.
4 - Levator ani and coccygeus muscles.
5 - Superior layer of fascia.
What is the difference between the pelvic diaphragm and the pelvic floor?
- The pelvic diaphragm includes the levator ani and coccygeus muscles, along with the surrounding layers of fascia.
- The pelvic floor includes the pelvic diaphragm, but also includes the perineal membrane and perineum.
What is the deep perineal pouch / space?
The region between the perineal membrane and inferior layer of fascia of the pelvic diaphragm.
What is a perineotomy / episiotomy?
A surgical cut to the perineum to aid childbirth.
List the erector spinae muscles.
1 - Iliocostalis.
2 - Longissimus.
3 - Spinalis.
