Class 1 Flashcards
Which structures enclose the posterior abdomen?
Lumbar vertebrae, intervertebral discs and inferior ribs.
What are the 9 regions of the abdomen?
Right hypochondriac Epigastric Left hypochondriac
Right flank Umbilical Left flank
Right iliac Hypogastric Left iliac
What are the 2 imaginary horizontal lines above and below the umbilicus?
Above - transpyloric
Below - transtubercular
Name the 3 flat muscles and 2 vertical muscles of the anterolateral abdominal wall.
3 flat muscles: external oblique, internal oblique, transversus abdominis.
2 vertical muscles: rectus abdominis, pyramidalis.
What are the actions and innervation of the external oblique?
Actions: compression of the abdominal cavity and lateral flexion.
Innervation: T7-T11 (lower 5 thoracoabdominal nerves) and T12 (R and L subcostal nerves).
What are the actions and innervation of the internal oblique?
Actions: compression of the abdominal cavity; unilateral contraction rotates the trunk vertically to 1 side.
Innervation: ventral rami of T7-T12 and L1.
What are the actions and innervation of the transversus abdominis?
Actions: aids forced respiration, supports the abdominal wall and raises intra-abdominal pressure.
Innervation: ventral rami of T7-T12 and L1.
What are the actions and innervation of the rectus abdominis?
Actions: flexion of the lumbar spine and forced expiration.
Innervation: ventral rami of T7-T12 and L1.
What is the rectus sheath?
This is formed by the aponeuroses of the 3 flat muscles (external oblique, internal oblique and transversus abdominis) and encloses the rectus abdominis and pyramidalis muscles.
How does the rectus sheath differ above and below the umbilicus?
Above: external oblique passes in front of the rectus as does half of the internal oblique (anterior wall of the sheath). Other half of internal oblique passes behind, as does the transversus abdominis (posterior wall of the sheath).
Below: all 3 muscles pass in front of the rectus –> all are now anterior (no posterior wall) and in contact with transversalis fascia.
Where is the umbilicus located on the abdominal wall?
L3/L4. Surface marking of aortic bifurcation.
Which dermatome is at the level of the umbilicus?
T10
What is the inguinal canal?
It is formed from layers of the anterior abdominal wall as these layers push through the wall during relocation of the gonads in fetal development. In males this canal carries the spermatic cords, in females the round ligament of the uterus. In both it carries the ilioinguinal nerve.
Where is the inguinal canal located?
Parallel to and above the medial half of the inguinal ligament. The canal is approx 4cm long.
What are the bony attachments of the inguinal ligament?
Pubic tubercle and anterior superior iliac spine.
Define cryptorchidism.
Failure of the testes to descend from the abdomen. Most common birth defect of male genitals.
What are the boundaries of the inguinal canal?
Anterior wall: aponeurosis of external oblique.
Posterior wall: transversalis fascia.
Roof: internal oblique and transversus abdominis.
Floor: inguinal ligament.
Where are the inguinal rings located?
Deep inguinal ring is located superiorly and is the entrance to the inguinal canal. Superficial inguinal ring is located inferiorly and lies 1cm above and superolateral to the pubic tubercle.
Which type of hernia is the most common?
Indirect inguinal hernia.
What is the difference between a direct and indirect inguinal hernia?
Direct: 1/3 of inguinal hernias. Abdominal contents pass through a weak spot in the muscles making up the posterior inguinal canal. Contents enter canal and may pass through the superficial inguinal ring. Abdominal contents don’t pass through the deep inguinal ring.
Indirect: 2/3 of inguinal hernias. Due to a congenital weakness of the deep inguinal ring which allows abdominal contents to enter into the inguinal canal and out through the deep inguinal ring.
What is a femoral hernia?
A hernia that occurs below the inguinal ligament. Abdominal contents pass into a weak area of the posterior wall of the femoral canal. More common in females and risk of strangulation.
What is a strangulated hernia?
A hernia in which the blood supply has been cut off to the protruding tissue.
What is an umbilical hernia?
Abdominal contents pass through a weakness in the abdominal wall at the site of the umbilicus. In adults umbilical hernias are acquired, not congenital.
What are the 4 histological functional layers of the gut tube?
1) Mucosa - a) epithelium, b) lamina propria, c) muscularis mucosae
2) Submucosa
3) Muscularis externa - outer longitudinal layer and inner circular layer
4) Serosa (intraperitoneal) or adventitia (retroperitoneal)
What are the 4 basic mucosal forms of the GI tract?
Protective: oral cavity, pharynx, oesophagus and anal canal.
Secretory: stomach.
Absorptive: small intestine.
Absorptive/protective: large intestine.
