Areas of the Abdomen Flashcards
Where is the inguinal triangle (Hesselbach’s triangle)?
Located within the inferomedial aspect of the abdominal wall
What is the inguinal triangle (Hesselbach’s triangle) alternatively known as?
The medial inguinal fossa
What are the borders of the inguinal triangle?
Medial – lateral border of the rectus abdominis muscle. Lateral – inferior epigastric vessels. Inferior – inguinal ligament
What is the clinical relevance of the inguinal triangle?
However, the triangle does demarcate an area of potential weakness in the abdominal wall – through which herniation of the abdominal contents can occur.
What is a hernia?
The protrusion of an organ or fascia through the wall of a cavity that normally contains it
What is the peritoneum?
Continuous membrane which lines the abdominal cavity (parietal) and covers the abdominal organs (visceral)
What is function of peritoneum?
It acts to support the viscera, and provides pathways for blood vessels and lymph to travel to and from the viscera.
What are the 2 layers of peritoneum?
- Parietal 2. Visceral Both types are made up of simple squamous epithelial cells called mesothelium
What does the parietal peritoneum line?
the internal surface of the abdominopelvic wall
What is the parietal peritoneum derived from?
Somatic mesoderm in the embryo
What nerve supply does the parietal peritoneum receive?
The same somatic nerve supply as the region of the abdominal wall that it lines; therefore, pain from the parietal peritoneum is well localised.
What does the visceral peritoneum line?
The visceral peritoneum invaginates to cover the majority of the abdominal viscera
What is the visceral peritoneum derived from?
Splanchnic mesoderm in the embryo
What nerve supply does the visceral peritoneum have?
The same autonomic nerve supply as the viscera it covers Unlike the parietal peritoneum, pain from the visceral peritoneum is poorly localised and the visceral peritoneum is only sensitive to stretch and chemical irritation.
Where is pain from the visceral peritoneum referred to?
Areas of the skin (dermatomes) which are supplied by the same sensory ganglia and spinal cord segments as the nerve fibres innervating the viscera
What is the peritoneal cavity?
A potential space between the parietal and visceral peritoneum. It normally contains only a small amount of lubricating fluid.
In order to adequately fulfil its functions, the peritoneum develops into a highly folded, complex structure. What is a mesentery?
Double layer of visceral peritoneum
What is function of mesentery?
It connects an intraperitoneal organ to (usually) the posterior abdominal wall. It provides a pathway for nerves, blood vessels and lymphatics to travel from the body wall to the viscera.
How is the mesentery named?
The mesentery of the small intestine is simply called ‘the mesentery’. Mesentery related to other parts of the gastrointestinal system is named according to the viscera it connects to, for example the transverse and sigmoid mesocolons, the mesoappendix.
What is the inguinal region?
The inguinal region is an area of the abdominal wall that extends from the ASIS to the pubic tubercle.
What is the inguinal canal?
The inguinal canal is a short passage that extends inferiorly and medially through the inferior part of the abdominal wall
What is purpose of inguinal canal?
Serves as a pathway by which structures can pass from the abdominal wall to the external genitalia
During development, where does the tissue that will become the gonads establish and then descend?
In the posterior wall and descend through the abdominal cavity
What is the gubernaculum?
A fibrous cord of tissue that attaches the inferior portion of the gonad to the future scrotum or labia and guides them during their descent
In males, what is the inguinal canal?
The pathway by which the testes leave the abdominal cavity and enter the scrotom
In the embryological stage,, what is the inguinal canal flanked by?
An out-pocketing of the peritoneum (processus vaginalis) and the abdominal musculature.
What happens to the processus vaginalis?
Normally degenerates
What can a failure of the processus vaginalis to degenerate usually cause?
An indirect inguinal hernia, a hydrocele, or interfere with the descent of the testes
In men, once the gubernaculum has shortened in the process of the descent of the testes, what does it become?
A small scrotal ligament, tethering the testes to the scrotum and limiting their movement.
In female, what is purpose of gubernaculum?
Attaches the ovaries to the uterus and future labia majora
Why are ovaries prevented from descending as far as the testes? Where do they move instead?
Ovaries are attached to the uterus by the gubernaculum. Instead move into the pelvic cavity
In females, what does the gubernaculum then become?
2 structures: the ovarian ligament and round ligament of the uterus
What is the mid-inguinal point?
Halfway between the pubic symphysis and the anterior superior iliac spine. The femoral pulse can be palpated here.
What is the midpoint of the inguinal ligament?
Halfway between the pubic tubercle and the anterior superior iliac spine (the two attachments of the inguinal ligament). The opening to the inguinal canal is located just above this point.
What is the inguinal canal bordered by?
Anterior, posterior, superior (roof) and inferior (floor) walls
What 2 openings does the inguinal canal have?
Superficial and deep rings
Describe the anterior wall of the inguinal canal
aponeurosis of the external oblique, reinforced by the internal oblique muscle laterally.
Describe the posterior wall of the inguinal canal
transversalis fascia
Describe the roof of the inguinal canal
transversalis fascia, internal oblique, and transversus abdominis
Describe the floor of the inguinal canal
Inguinal ligament (a ‘rolled up’ portion of the external oblique aponeurosis), thickened medially by the lacunar ligament.
During periods of increased intra-abdominal pressure, what happens to the abdominal viscera? How is herniation of viscera into the canal prevented?
The abdominal viscera are pushed into the posterior wall of the inguinal canal To prevent herniation of viscera into the canal, the muscles of the anterior and posterior wall contract, and ‘clamp down’ on the canal.
During periods of increased intra-abdominal pressure, what happens to the abdominal viscera? How is herniation of viscera into the canal prevented?
The abdominal viscera are pushed into the posterior wall of the inguinal canal To prevent herniation of viscera into the canal, the muscles of the anterior and posterior wall contract, and ‘clamp down’ on the canal.
Where is the deep (internal) ring of the inguinal canal found?
Above the midpoint of the inguinal ligament which is lateral to the epigastric vessels
What is the deep (internal) ring of the inguinal canal created by?
The transversalis fascia, which invaginates to form a covering of the contents of the inguinal canal.
Where is the superficial (external) ring of the inguinal canal?
Marks the end of the inguinal canal, and lies just superior to the pubic tubercle
What is the superficial (external) ring of the inguinal canal formed by?
It is a triangle shaped opening, formed by the evagination of the external oblique, which forms another covering of the inguinal canal contents. This opening contains intercrural fibres, which run perpendicular to the aponeurosis of the external oblique and prevent the ring from widening
What does the inguinal canal in men contain?
Spermatic cord –> contains neurovascular and reproductive structures that supply and drain the testes
What does the inguinal canal in females contain?
Round ligament –> originates from the uterine horn and travels through the inguinal canal to attach at the labia majora
Where does the ilioinguinal nerve pass?
Only travels through part of the inguinal canal, exiting via the superficial inguinal ring (it does not pass through the deep inguinal ring)
What is function of ilioinguinal nerve?
Contributes towards the sensory innervation of the genitalia This is the nerve most at risk of damage during an inguinal hernia repair.
Where is the genital branch of the genitofemoral nerve found? What is its purpose?
In the inguinal canal - supplies the cremaster muscle and anterior scrotal skin in males, and the skin of the mons pubis and labia majora in females
What are the 2 main categories of inguinal hernias?
Direct and indirect
What is an indirect inguinal hernia?
Where the peritoneal sac enters the inguinal canal through the deep inguinal ring.
What is a direct inguinal hernia?
Where the peritoneal sac enters the inguinal canal though the posterior wall of the inguinal canal.
Contents of male inguinal canal
Male – spermatic cord
- Ductus deferens
- Artery of ductus deferens
- Testicular artery
- Cremasteric artery
- Pampiniform venous plexus
- Sympathetic nerve fibres
- Genital branch of genitofemoral nerve
- Lymphatic vessels
Contents of female inguinal canal
Round ligament of the uterus
What is a direct inguinal hernia?
Direct (acquired)
- Protrusion occurs at level of superficial ring
- Leaves abdomen medial to inferior epigastric vessels
- Hernial sac limited by peritoneum and transversalis fascia
- Does not usually enter scrotum
Are indirect hernias more common in men or women?
Men - opening is bigger
What is an indirect hernia?
Indirect (congenital)
- Protrusion occurs at level of deep ring (patent processus vaginalis; typically in young males)
- Leaves abdomen lateral to inferior epigastric vessels; traverses canal and can enter the scrotum via superficial ring
- Hernial sac in persistent processes vaginalis
- More common than direct
What is hydrocele?
A type of swelling in the scrotum that occurs when fluid collects in the thin sheath surrounding a testicle
- common in newborns and usually disappears without treatment by age 1
- older boys and adult men can develop a hydrocele due to inflammation or injury within the scrotum
Describe the location of the epigastric vessels in relation to the deep inguinal ring
Inferior epigastric vessels are medial to the deep inguinal canal
What is a common cause of an indirect hernia?
Patent processus vaginalis
