SDL - Anterior Wall and Inguinal Region Flashcards
What is an aponeuorsis?
A flat tendinous structure that connects anterolateral abdominal wall muscles to the linea alba
What are the functions of the anterior abdominal wall muscles?
- Movement
- Increase intra-abdominal pressure
What is the nerve supply to the skin and muscle of the anterior abdominal wall?
Continuation of intercostal nerves (thorcoabdominal nerves), subcostal nerves, iliohypogastric nerves, ilioinguinal nerves
What dermatome lies at the level of the xiphisternum?
6
Which dermatome lies at the level of the umbilicus?
10
Which dermatome lies at the level of the pubic tubercle?
T12/L1
The membranous layer of superficial fascia on the anterior abdominal wall (Scarpa’s fascia) is continuous inferiorly with the membranous layer of superficial fascia of the perineum.
What is the name given to this fascia in the perineum?
Calle’s fascia
What direction do the fibres of the external oblique muscles run?
Downwards and forwards
What is the free inferior border of the external oblique aponeurosis thickened to form?
The inguinal ligament
What is found superior to the pubic tubercle?
The superficial inguinal ring
What is the superficial inguinal ring?
A triangular ‘gap’ in the aponeurosis, through which the spermatic cord or round ligament of the uterus passes
What passes through the inguinal canal in men?
Spermatic cord
What passes through the inguinal canal in women?
Round ligament of uterus, attaching the uterus to the labia majora
How is the aponeurosis of external oblique arranged at this point? Which component of the spermatic cord is formed from this aponeurosis?
Forms the anterior wall of the inguinal canal; external spermatic fascia
What direction do the internal oblique fibres run?
Downwards and backwards
Where do the fibres of the internal oblique originate?
Lateral third/two thirds of Inguinal ligament and iliac crest
Where does the inguinal ligament run?
From anterior iliac spine to pubic tubercle
How do the fibres of internal oblique relate to the inguinal ligament?
Form roof then posterior wall as conjoint tendon posterior to superficial inguinal ring.
In which direction do the fibres of transversus abdominis run?
Transversely
How do the fibres of transversus abdominis relate to the inguinal ligament?
Superior to the deep inguinal ring, roof and then posterior wall as conjoint tendon.
Where do fibres of transversus abdominis originate?
Internal surfaces of costal cartilages of ribs 7-12, thoracolumbar fascia, anterior two thirds of iliac crest, iliopectineal arch
Where do fibres of transversus abdominis insert?
Linea alba, aponeurosis of internal abdominal oblique muscle; pubic crest, pectinal line of pubis
What is the conjoint tendon?
Union of internal oblique and transversus abdominis
Where is the conjoint tendon?
Posterior to superficial inguinal ring
What is the transversalis fascia?
Thin connective layer between transversalis abdominis and parietal peritoneum
Where is the transversalis fascia?
Thickest at level of inguinal canal
What is the rectus abdominis enclosed within?
A fibrous sheath formed from the aponeuroses of the three anterolateral abdominal muscles.
What are the attachments of the rectus abdominis?
Sternum, ribs 5-7 and pubic creat
What is function of rectus abdominis?
Flexion of vertebral column
What is the arcuate line?
The lower limit of the posterior layer of the rectus sheath. It is found halfway between the umbilicus and the pubic crest .
At this line, the aponeurosis of the transveralis abdominis also passes anterior to the rectus abdominis.
Only the transveralis fascia passes posterior to the rectus abdominis below this line.
What is the linea alba?
A fibrous structure that runs down the midline of the abdomen from the xiphoid process to the pubic symphysis
It separates the right and left rectus abdominis muscles
What is the linea alba formed from?
The fusion of the aponeuroses of the muscles of the anterior abdominal wall
What is the linea semilunaris?
Two curved tendinous lines placed one on either side of the linea alba. Each corresponds with the lateral border of the rectus abdominis
Which vessels run in the rectus sheath, deep to the rectus abdominis muscle?
Inferior epigastric vessel
What is the inguinal canal?
An oblique passage lying just above the medial half of the inguinal ligament. It extends from the deep inguinal ring to the superficial inguinal ring
The canal forms a weak point on the anterior abdominal wall, especially in males due to its larger size
What is the deep inguinal ring?
A defect in transversalis fascia bounded laterally by the most medial fibres of transversus abdominis
What does the inguinal canal act as in males?
The canal transmits the spermatic cord in the male. It is the route by which the testis descends into the scrotum in the male foetus.
How do the testes descend?
Push through anterior abdominal wall, trailing its ductus deferens
As this happens, the testes and the ductus deferens acquire a layer of fascia
What is the tunica vaginalis?
Inside the scrotum, the testes are covered almost entirely by the tunica vaginalis, a closed sac of parietal peritoneal origin that contains a small amount of viscous fluid. This sac covers the anterior surface and sides of each testicle and works much like the peritoneal sac, lubricating the surfaces of the testes and allowing for friction-free movement.
What is the tunica vaginalis derived from?
Processus vaginalis
What is the processus vaginalis?
An embryonic outpouching of the patietal peritoneum
In males, it precedes the testis in their descent down within the gubernaculum, and closes.
What is the gubernaculum?
A fibrous cord (e.g. attaches foetal testis to bottom of scrotum in males)
The gubernaculum aids in the descent of the gonads (both testes and ovaries). The testes descend to a greater degree than the ovaries and ultimately pass through the inguinal canal.
How does the gubernaculum cause descent of gonads?
Failing to elongate in proportion to rest of foetus causes descent
What is the cremasteric reflex?
Reflex observed when superomedial portion of thigh is stroked.
This tightens the cremaster muscles which elevates the testes on the ispilateral side
Where is the deep inguinal ring located?
2cm above the midpoint of the inguinal ligament
What lies in the medial border of the deep ring?
The inferior epigastric artery
What lies at the lateral border of the deep ring?
The transversalis fascia
What are the boundaries of the superficial ring?
Medial and lateral crura of the external oblique muscle
What is the approx length of the inguinal canal?
4cm
What forms the anterior wall of the inguinal canal?
The aponeurosis of the external oblique, 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, and transversus abdominis.
What forms the floor of the inguinal canal?
Inguinal ligament (a ‘rolled up’ portion of the external oblique aponeurosis)
Which nerve enters the inguinal canal through the deep ring? What does it supply?
Genital branch of the genitofemoral nerve
Supplies the labia majora and the mons pubis in females
Supplies the cremaster and skin of scrotum in males
What is the mons pubis?
A pad of fatty tissue that covers the pubic bone (more prominent in females)
What is the cremaster?
A paired muscle of the pelvis and perineum that is fully developed only in the external genitalia of males.
Being located between the internal and external layers of spermatic fascia, cremaster covers the testes and spermatic cord.
How does the ilioinguinal nerve enter the inguinal canal?
By virtue of running within the layers of the anterior abdominal wall, between the transversus abdominis and the internal oblique
When the inguinal canal is formed, the nerve ‘happens’ to be in the canal
What is a hernia?
Protrusion of a structure through the body cavity in which it is normally contained.
What is a direct hernia?
Protrusion of small intestine through the anterior abdominal wall at the level of the superficial inguinal ring (Hesselbach’s triangle). Although it bulges through the wall, it doesn’t usually penetrate through the conjoint tendon. Think of a finger through a balloon.
What is an indirect hernia?
Protrusion of small intestine through the anterior abdominal wall at the level of the deep inguinal ring. Enters spermatic cord and passes through the inguinal canal – it can enter the scrotum.
If a hernia was reducible, what does this mean?
It can be returned to its existing cavity i.e. the SI can be pushed back into the abdomen
How can you distinguish between a direct and indirect hernia?
Use an ultrasound and, finding the interior epigastric artery, identify if the hernia is associated with the deep or superficial inguinal ring
