Chapter Three - Abdomen and Pelvis

Question 1

What are the superior, posterior, antero-lateral, and inferior boundaries of the abdominal pelvis?

Answer 1

• Superiorly: Diaphragm
• Posteriorly: Lumbar vertebrae and posterior abdominal wall muscles
• Antero-laterally: Muscles of the anterolateral abdominal wall
• Inferiorly: continuous with the pelvic cavity

Question 2

What are the three types of movement of the trunk (i.e. vertebral column/spine)?

Answer 2

Extension/flexion

Lateral (side) flexion

Rotation

Question 3

Where is the exxternal oblique situated? Where is its origin? Its insertion? What is(are) its action(s)? It is innervated by which nerve(s)?

Answer 3

Origin: lower eight ribs

Action: bilateral: Flexion of spine; compression of abdominal contents(when both sides contract)
unilateral: Lateral flexion (ipsilateral) and rotation (contralateral) of spine/trunk(when one side contracts)

Insertion: xiphoid process, linea alba (through aponeurosis), iliac crest, anterior superior iliac spine (ASIS), pubic crest (through inguinal ligament)

Nerve: intercostal nerves (8th – 12th)

Linea alba = white line

Question 4

What is the inguinal ligament? From where to where does it run?

Answer 4

Inguinal ligament is a thickened inferior border of External oblique aponeurosis running between ASIS and pubis.

Question 5

Where is the internal oblique situated? Where is its origin? Its insertion? What is(are) its action(s)? It is innervated by which nerve(s)?

Answer 5

Origin: inguinal ligament, iliac crest, thoracolumbar fascia(from the inferior, going up)

Action:bilateral: Flexion of spine; compression of abdominal contentsunilateral: Lateral flexion and rotation of trunk

Insertion: cartilage of ribs 8-10, linea alba (through aponeurosis)

Nerve: intercostal nerves (8th – 12th)

Question 6

Where is the transversus abdominis situated? Where is its origin? Its insertion? What is(are) its action(s)? It is innervated by which nerve(s)?

Answer 6

Origin: inguinal ligament, iliac crest, thoracolumbar fascia, cartilage of ribs 6-12

Action: Compresses abdominal contents (Too deep to move the trunk as much as the others)

Insertion: linea alba (through aponeurosis)

Nerve: intercostal nerves (7th -12th)

Question 7

Where is the rectus abdominis situated? Where is its origin? Its insertion? What is(are) its action(s)? It is innervated by which nerve(s)?

Answer 7

Origin: pubic crest

Action: Flexes vertebral column, compresses abdominal contents

Insertion: cartilage of ribs 5-7, xiphoid process

Nerve: intercostal nerves (7th – 12th)

Question 8

Fill in the blanks: aponeuroses of the (…) muscles contribute to the formation of (…).

Answer 8

Aponeuroses of the External oblique, Internal oblique and Transversus abdominis muscles contribute to the formation of the rectus sheath.

Question 9

Functional considerations:

What are the actions of the anterior abdominal wall muscles? What is important to note about the actions of the obliques? Be precise.

Answer 9

Functional considerations:

Actions of the anterior abdominal wall muscles:

1. Movement: flexion, lateral flexion and rotation of the trunk.
   Note: the obliques act as muscle couples to accomplish rotation:
   left external oblique and right internal oblique rotate the trunk to the right;right external oblique and left internal oblique rotate the trunk to the left.
2. Support to the abdominal viscera:
   Abdominal cavity acts as a pressure cylinder. Contraction of abdominal

muscles increases intraabdominal pressure, important in:

normal micturition, defecation, parturition and respiration;

forced expiration, i.e., coughing, sneezing;

normal posture and weight lifting.

Question 10

Name the keys structures to be identified in the lab, on the abdomen.

Answer 10

Question 11

What are some of the antero-lateral abdominal wall layers, other than muscles?

Answer 11

Question 12

What is the inguinal canal? Why is it important? Which are its two openings?

Answer 12

The inguinal canal is a passage in the anterior abdominal wall. It is important because the testes descend through it in males during development, and loops of gut may be forced through it as well.

Openings of the inguinal canal:superficial and deep inguinal rings.

Question 13

What are the contents of the inguinal canal in males?

Answer 13

Contents of the inguinal canal in males:

vas deferens (ductus deferens), testicular artery and vein, ilioinguinal nerve, genital branch of the genitofemoral nerve, autonomic nerves to the testis and lymph drainage from the testis. These structures descend with the testis and form the spermatic cord.

Details (e.g. nerves) not as important

Question 14

What are the contents of the inguinal canal in females?

Answer 14

Contents of the inguinal canal in females:
Round ligament of the uterus – supports the position of the uterus.

Question 15

What is a hernia? Where to they usually occur?

Answer 15

An abnormal prolapse (exit) of tissues or organs through the wall of the cavity they normally reside in is called a hernia. Hernias most commonly involve the abdomen.

Question 16

90% of hernias are where? 75% of hernias are where? What are the two types of inguinal hernias?

Answer 16

Approximately 90% of all hernias areinguinal hernias = in the groin (inguinal) region.

75% of all inguinal hernias are in males.

Inguinal hernias:

1. Direct
2. Indirect

Question 17

Describe an indirect inguinal hernia and a direct inguinal hernia.

Answer 17

Indirect inguinal hernias pass through the deep inguinal ring, inguinal canal andsuperficial inguinal ring. They are 20x more common in males than females.

Direct inguinal hernias do not pass through the inguinal canal, they push directlythrough the superficial inguinal ring. They are most common in males over 40.

Question 18

What type of hernia is the most common in females? Where does it occur specifically? Give the six types of possible hernias.

Answer 18

Other types of hernias
• Femoral hernia is the most common type in females but still more frequent in males. Femoral hernia occurs posterior and inferior to the inguinal ligament.

Question 19

What does the abdominal digestive tract consist of? What are the organs, glands and other structures associated with the alimentary tract?

Answer 19

Abdominal viscera

Abdominal digestive tract: stomach, small intestine (duodenum, jejunum and ileum), and large intestine (caecum, appendix, ascending colon, transverse colon, descending colon, sigmoid colon, rectum).

Organs, glands and other structures associated with the alimentary tract:

liver, gallbladder, pancreas, spleen

abdominal aorta and its branches

portal vein

Question 20

Describe the three parts of the alimentart tract and what they contain.

Answer 20

Development of the alimentary tract

Foregut (Top of the first green line)
terminal esophagus, stomach, liver, pancreas, 1st part of duodenum

Midgut (Tube between first green line and second one)
the rest of duodenum,
jejunum, ileum, caecum, appendix, ascending colon and the right 2/3s of the transverse colon

Hindgut (Bottom of the last green line)

left 1/3 of the transverse colon, descending colon, sigmoid colon, rectum and upper 2/3rd of anal canal

Question 21

Name the three branches of the abdominal aorta and which organs they supply.

Answer 21

Blood supply to digestive tract and related organs

Branches of the abdominal aorta:

1. Celiac trunk: to liver, spleen, stomach, duodenum (first part). (foregut)
2. Superior mesenteric artery: to small intestine and first 2/3s of large intestine. (midgut)
3. Inferior mesenteric artery: to the last 1/3 of large intestine. (hindgut)

Question 22

What are the types of innervation of the digestive tract? Which nerves are responsible for which?

Answer 22

Innervation of the digestive tract: ANS

Sympathetic innervation:

Thoracic splanchnic nerves from sympathetic chain.

Parasympathetic: (“Rest and digest”)

Cranio-sacral origin of parasympathetic innervation:
§ Vagus nerve (CN X) and

§ Pelvic splanchnic nerves(S2, S3, S4).

Question 23

What does the bony pelvis consist of?

Answer 23

Pelvis

Bony pelvis: 2 hip bones (L + R), each consisting of:

1. Ilium
2. Pubis
3. Ischium

Question 24

What is the pelvic floor? What does it separate? What does its contractions do? Lack of exercise can lead to what? They are stretched in what situation?

Answer 24

Pelvic floor (or pelvic diaphragm)

Pelvic floor is a muscular layer that separates the abdomino-pelvic cavity from the perineum (area of external genitalia).

Pelvic floor muscles support pelvic viscera; their contractions also control/tighten the sphincter muscles around the openings of the urethra, anus and vagina. Relaxing the pelvic floor muscles allows passage of urine and feces.

Lack of exercise can lead to incontinence (male and female).

Muscles of the pelvic floor are stretched during child birth.

Question 25

Name the two pelvic muscles. The first one is composed of which two smaller muscles?

Answer 25

Pelvic floor muscles are: 1) Levator ani muscle, composed of two muscles: Pubococcygeus (a) Iliococcygeus (b) 2) Coccygeus (or Ischiococcygeus) (c) The right and left levator ani muscles lie horizontally in the floor of the pelvis and transmit the urethra, vagina and anal canal.

Question 26

What is the pudendal nerve? What is its origin? What does the pudendal nerve's motor branches supply? What does the pudendal nerve's sensory branches carry sensation for?

Answer 26

Pudendal nerve Nerve to the pelvic floor muscles. The origin of the pudendal nerve is from sacral spinal nerves S2, S3, S4. (only spinal nerves that have parasympathetic components) Pudendal nerve motorbranches supply muscles of the pelvic floor (Levator ani, Coccygeus) and sphincters surrounding the orifices (urethra, vagina, anal canal). Pudendal nerve sensorybranches carry sensation from the skin of the perineum and the external genitalia.