Inguinal canal Flashcards
what is the inguinal canal?
a short passage that extends inferiorly and medially, through the inferior part of the abdominal wall
where is the inguinal canal in relation to the inguinal ligament?
superior and parallel to the inguinal ligament
what does the inguinal canal act as?
pathway by which structures can pass from the abdominal wall to the external genitalia
what is the clinical importance of the inguinal canal?
a potential weakness in the abdominal wall, and therefore a common site of herniation
what happens to the testes during development? where does it occur?
testes establish in the posterior abdominal wall, and descend into the scrotum
what guides the descend of the testes?
a fibrous cord of tissue called the gubernaculum attaches the inferior portion of the gonad to the future scrotum, and guides them during their descent
what is the significance of the inguinal canal in the development of the testes?
the pathway by which the testes are able to leave the abdominal cavity and enter the scrotum
what is the inguinal canal flanked by in the embryological stage? what is it called and it’s fate?
an outpocketing of the peritoneum, and the abdominal musculature
outpocketing called processus vaginalis (normally degenerates)
what happens if the processus vaginalis fail to degenerate?
result in indirect inguinal hernia
what is the function of the gubernaculum in women?
attaches the ovaries to the uterus and future labia majora
what are the ovaries attached to the uterus by?
gubernaculum
what does the attachment of ovaries to uterus by gubernaculum prevent?
prevented from descending as far as the testes, and instead moving into the pelvic cavity
in females, what does the gubernaculum then become?
the ovarian ligament, and round ligament of uterus
what is the mid-inguinal point?
halfway between the pubic symphysis and anterior superior iliac spine
which structure is at the mid-inguinal point?
femoral artery crosses into the lower limb
what is the midpoint of the inguinal ligament?
halfway between ASIS and pubic tubercle (superior rami of pubis)
what is at the midpoint of the inguinal ligament?
femoral nerve
where is the opening to the inguinal ligament?
just above the midpoint of the inguinal ligament
what is the inguinal canal made up of?
anterior & posterior walls
superficial & deep rings (openings)
roof and floor (or superior and inferior walls)
what forms the anterior wall of the inguinal canal
aponeurosis of the external oblique and reinforced by the internal oblique muscle laterally
what forms the posterior wall of the inguinal canal?
transversalis fascia
what forms the roof of the inguinal canal?
transversalis fascia, internal oblique & transversus abdominis
what forms the floor of the inguinal ligament?
a ‘rolled up’ portion of the external oblique aponeurosis & thickened medially by the lacunar ligament
what happens during periods of increased intra-abdominal pressure?
the abdominal viscera are pushed into the inguinal canal
what does the body do during periods of increased intra-abdominal pressure? why?
to prevent herniation
the muscles of the anterior & posterior wall contract and ‘clamp down’ on canal
what are the 2 openings to the inguinal canal known as?
rings
where is the deep (internal) ring found?
above the midpoint of the inguinal ligament, which is lateral to the epigastric vessels
what is the deep internal ring created by?
transversalis fascia, which invaginates to form a covering of the contents of the inguinal canal
where is the superficial (external) ring found?
just superior to the pubic tubercle
what does the superficial (external) ring mark?
the end of the inguinal canal
what does the superficial (external) ring look like?
a triangle shaped opening
what forms the superficial (external) ring?
formed by the evagination of the external oblique, which forms another covering of the inguinal canal contents
what does the superficial (external) ring contain?
intercrural fibres
where do intercrural fibres run? what does it prevent?
perpendicular to the aponeurosis of the external oblique and prevent the ring from widening?
what passes through the inguinal canal in men? what is it’s function?
spermatic cord
supply and drain testes
what passes through the inguinal canal in women?
round ligament of the uterus transverses
what is special about the walls of the inguinal canal? why?
walls of inguinal canal are usually collapsed around their contents, preventing other structures from potentially entering the canal and becoming stuck
what is a hernia?
protrusion of an organ of fascia through the wall of cavity that normally contain it
what are the 2 main categories that hernias involving the inguinal canal can be divided into?
indirect & direct
what is indirect hernia involving the inguinal canal?
where the peritoneal sac enters the inguinal canal through the deep inguinal ring
what is direct hernia involving the inguinal canal?
where the peritoneal sac enters the inguinal canal through the posterior wall of the inguinal canal
what can both direct and indirect hernia involving inguinal canal present as?
lumps in the scrotum or labia majora
explain indirect inguinal hernia
more common, has congenital origin
due to failure of the processus vaginalis to regress
peritoneal sac enters the inguinal canal via the deep inguinal ring
degree to which the sac herniates depends on the amount of processus vaginalis still present
as the sac moves through the inguinal canal, it acquires the same 3 coverings as the contents of the canal
explain direct inguinal hernias
in contrast to the indirect hernia, this is aquired in origin, due to weakening in the abdominal musculature
the peritoneal sac originates from an area medial to the epigastric vessels and bulges into the inguinal canal via the posterior wall
