Inguinal Canal - humsc.net
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Inguinal Canal Dr Ashraf Sadek PhD, MD, MRCPCH Assistant Professor of anatomy and embryology Click to add text
Transcript of Inguinal Canal - humsc.net
Inguinal Canal
Dr Ashraf Sadek PhD, MD, MRCPCH
Assistant Professor of anatomy and embryology
Click to add text
❑ It is an oblique intermuscular passage extending in a downward and medial direction, above and parallel to the medial half of the inguinal ligament.
❑ Length: Begins at the deep inguinal ring & ends at the superficial inguinal ring (4cm).
❑ Sex diff.: Larger in males & contains the spermatic cord, while smaller in females & contains the round ligament of uterus
Deep inguinal ring:• Def.: Oval opening in fascia
transversalis
• Site: ½ inch above midpoint of inguinal ligament
• Relations:
• It lies lateral to the inferior epigastricvessels.
• Its margins from fascia transversalisare prolonged around the spermatic cord & testis to form the internal spermatic fascia.
• Def: Triangular opening in external oblique aponeurosis.
• Site: above pubic tubercle
• Relations:
Base: pubic crest.
Sides: Crura (medial & lateral).
• Margins are prolonged around testis & spermatic cord forming external spermatic fascia.
Superficial inguinal ring:
The inguinal canal has :1)Anterior wall2)Posterior wall3)Roof4)Floor
The inguinal canal
❑Fascia transversalis
❑Transversusabdominis
❑Internal oblique
❑Aponeurosisof external oblique
Boundaries of inguinal canal:2 structures in each wall1) Anterior wall: external
oblique along its whole length + internal oblique on lateral ⅓
2) Roof: Lower arching fibers of internal oblique & transversus abdominis( conjoint tendon )
3) Posterior wall: Fascia transversalis along its whole length + conjoint tendon on its medial ⅓
4) Floor: inguinal ligament along its whole length + lacunar ligament on its medial end.
Anterior wall: along the whole length➔ aponeurosis of external oblique + on lateral ⅓ ➔ fleshy fibers of internal oblique
The anterior wall is weakened medially by the presence of the superficial inguinal ring.
• Along the entire length of the canal by the aponeurosisof the external oblique muscle.
• It is reinforced laterally by the fleshy fibers of internal oblique muscle
Anterior wall
Roof is formed by arching fibers of internal oblique and transversus abdominis ( conjoint tendon )
Anterior wall
roof
Posterior wall
Posterior wall
• The entire length of the canal by the fascia transversalis.
• It is reinforced along its medial one-third by the conjoint tendon
• The position of the conjoint tendon posterior to the superficial inguinal ring provides support to a potential point of weakness in the anterior abdominal wall.
Floor
• The floor is formed by concave upper surface of the inguinal ligament & by the lacunar ligament at its medial end.
Contents
1) The spermatic cord in males, the round ligament of the uterus in females
2) The ilioinguinal nerve (L1) in both males & females.
• The inguinal canal causes weakness in the anterior abdwall. Such weakness is compensated by the following:
1. Obliquity of the canal so the 2 rings are not opposite each other.2. Deep ring is supported anteriorly by internal oblique.3. Superficial ring is supported posteriorly by the conjoint tendon.4. The triple relation of the of the internal oblique to the canal; ant. ,roof & post.→when it contracts ➔ Shutter mechanism
◼ When great straining efforts may be necessary, as in defecation andparturition, the person naturally tends to assume the squattingposition.
◼ The hip joints are flexed and the anterior surfaces of the thighs arebrought up against the anterior abdominal wall.
◼ By this means the lower part of the anterior abdominal wall isprotected by the thighs.
Inguinal Triangle(Hesselbach’s triangle)
• Laterally: Inferior epigastric artery
• Medially: Lateral border of rectus abdominis
• Inferiorly: Inguinal ligament
• This triangle is the site of direct inguinal hernia.
Applied anatomyInguinal hernia
• Hernia is the protrusion of abdominal contents (usually intestine) within a sac of peritoneum through a weak point in the abdominal wall
• 2 types:
1. Indirect (oblique)inguinal hernia.
2. Direct inguinal hernia.
Inguinal hernias are more common in
males due to the wider & well developed
Inguinal canals
Oblique inguinal Hernia Direct inguinal Hernia
More frequent 80-90% Less frequent 10-20%
Usually congenital (infants & young adults)
In old age (over 50yrs)
Usually unilateral Usually bilateral
Bulges through deep inguinal ring ➔scrotum
Bulges through inguinal triangle➔ doesn’t reach scrotum
Neck of hernia sac is lateral to inf. epigastric vessels
Neck of hernia sac is medial to inf. epigastric vessels
Line of descent is downwards & medially Line of descent is directly forward through posterior wall of inguinal triangle
Commonly obstructed (strangulated) at deep inguinal ring
Rarely obstructed as it has a wider neck
Indirect (oblique) inguinal hernia
• Herniation starts at deep inguinal ring, along the canal to the superficial inguinal ring.
• Arises lateral to the inferior epigastric artery.
• Usually descends to the scrotum.
• Hernia pushes directly forward through the posterior wall of the inguinal canal (i.ethrough the inguinal triangle)
• Arises medial to the inferior epigastricartery.
• Usually doesn’t descend to the scrotum.
• To differentiate between direct & indirect hernia by deep inguinal ring test
Direct inguinal hernia
1) Oblique inguinal hernia arises lateral to inferior epigastric artery
2) Direct inguinal hernia arises medial to inferior epigastric artery
Rectusabdominis
Retroperitoneal Structures
Muscles:
Posterior Abdominal Wall
Quadratus Lumborum
Psoas Major & Minor
Iliacus
Psoas Major Muscle
- Sides of bodies -Transverse processes -The intervertebral discsOf T12, L1 to L5
Origin
With iliacus into lesser trochanter of thefemur
Insertion
Anterior rami of L2,3,4
Flexion of thigh on the trunkOr flexion of trunk on thigh as inSitting up from lying position
Nerve Supply:
Action:
Iliacus Muscle
- iliac fossa,
Origin
InsertionWith psoas major into lessertrochanter of femur
Femoral nerve
Nerve Supply
Action
Flexion of thigh on the trunkOr flexion of trunk on thigh as inSitting up from lying position
Psoas Minor Muscle
Origin
Insertion
Anterior rami of L1
Weak Flexion of trunk
Note: Psoas minor may be absent
Nerve Supply:
Sides of bodies of T12 and LI vertebrae and intervening intervertebral disc
ILiopectineal eminence
Action:
Quadratus Lumborum Muscle
Origin
Nerve Supply
Insertion
-iliolumbar ligament, - iliac crest
-Tip of tansverse processes of LI to L 4- inferior border of rib 12
Anterior rami of T12 and L1 to L4
Depress and stabilize rib XII and some lateral flexion of trunk
Action
Fascia on the posterior abdominal wall
1- Psoas fascia2- Fascia iliaca3- Thoracolumbar fascia
- This fascia covers the deep muscles of the back and the trunk. - In the lumbar region, it is very thick, well-defined into 3 layers:
1. The posterior layer:Passes behind the erector spinae muscle and is attachedto the spines of the lumbarand sacral vertebrae .
Fascia on the posterior abdominal wall
2. Middle layer: covers the back of the quadratus lumborum m. & attached to the tips
of the transverse processes of the lumbar vertebrae.
3. The anterior layer: Infront of the quadratus lumborum and is attached medially to anterior surfaces of the transverse processes of the lumbar vertebrae .
Fascia on the posterior abdominal wall
- Laterally, the three layers form the aponeurotic origin of transversusabdominis and internal oblique.
