Anterior Abdominal Wall/ Inguinal Canal Flashcards
Basic Layers of the Anterior Abdominal Wall
(1) Skin
(2) Superficial Fascia
(3) Muscles
(4) Transversalis fascia
(5) Extrapertioneal connective tissue
(6) Peritoneum
The layers of the superificial fascia of the Anterior Abdominal wall, above the umbilicus. Below the umbilicus?
Above- only fat
Below (2 layers):
- The superficial fatty fascia [Fascia of Camper’s which is replaced by the subcutaneous Dartos muscle in the scrotum]
- The deep membranous fascia [Fascia of Scarpa’s which is continuous with the fascia of the perineum (Colles’ Facia)]
The Antero-Lateral Muscles of the Anterior Abdominal Wall
(3):
External Oblique
Internal Oblique
Transversus abdominis
The midline muscles of the Anterior Abdominal Wall
(3):
Rectus Abdominis
Pyramidalis
Cremaster Muscle
What innervates the Oblique muscles and the Transversus Abdominis
The Ventral Rami of the six inferior thoracic nerves + the first lumbar nerves (No lumbar nerves for the external oblique)
What innervates the Pyramidalis muscle?
Iliohypogastric nerve
What innervates Rectus Abdominis?
Ventral rami of the six inferior thoracic nerves
Derivation and insertion of the Cremaster muscle
Derived from the lower arched fibers of internal oblique. The muscle fibers descend on the spermatic cord to form loops around it.
Inserted into the Pubic Tubercle
Innervation of the Cremaster Muscle
The Genitofemoral Nerve
Function of the Cremaster Muscle
To suspend the Testes and to pull them closer to the body in cold temperature (Cremasteric Reflex)
What is the Rectus Sheath and what are its contents?
-An aponeurotic sheath formed by the fusion of the aponeuroses of the external oblique, internal oblique and transverse muscle of the abdomen.
CONTENTS:
- 2 Muscles (rectus abdominis, pyramidalis)
- 2 Vessels (superior and inferior epigastric vessels)
- Lower 6 intercostal nerves
The 3 lines which the Rectus Abdominis is related to
- Line Alba
- Linea Semilunaris
- Arcuate Line
What defines a Direct vs and Indirect Hernia
Direct- Exit abdominal wall medial to the INFERIOR EPIGASTRIC ARTERY via Hesselbech’s Triangle
Indirect- Exit abdominal wall lateral to the inferior epigastric artery, through the deep inguinal ring
Line Alba
Tendinous median raphe between the two rectus abdominis muscles, formed by the fusion of the aponeuroses of the external oblique, internal oblique and transverse abdominal muscles. Extends from the Xiphoid process to the pubic symphysis.
Linea Semilunaris
A curved line along the lateral border of the rectus abdominis
Arcuate line
Cresent-shaped line marking the inferior limit of the posterior layer of the rectus sheath. Anterior to that line, the inferior epigastric artery ascends to enter the sheath.
At 26 weeks, what process generally begins?
The descent of testicles from their position in the posterior abdominal wall to the deep inguinal rings. This change occurs as the fetal pelvis enlarges and the body or trunk of the embryo elongates
Gubernaculum Testis
A mesenchymal band that extends from the caudal part of the testis along the course of its descent in the inguinal canal. Functions like a rubberband, anchoring the testis to the scrotum and guiding its descent into the scrotum. Forms a path through the anterior abdominal wall for the processus vaginalis to follow during formation of the inguinal canal
Processus Vaginalis
An outpouching of the peritoneum which develops ventral to the gubernaculum
As the testis and ductus deferens descend, they are ensheathed by the fascial extensions of the abdominal wall. What are these extensions and what do they become?
- The extension of transversalis fascia becomes internal spermatic fascia
- The extension of internal oblique muscle becomes Cremasteric muscle
- The extension of external oblique aponeurosis becomes external spermatic fascia
Tunica Vaginalis
During the perinatal period, the connecting stalk of the processus normally obliterates, forming this serous membrane (tunica vaginalis) which covers front and sides of the testes
Inguinal canal
The inguinal canal is a passage in the anterior abdominal wall which in men conveys the spermatic cord and in women the round ligament. The inguinal canal is larger and more prominent in men. There is one inguinal canal on each side of the midline.
The direction, path and size of the Inguinal canal
It is 4cm long, directed downwards, forwards and medially (like the external oblique) and is larger in males.
It begins at the deep inguinal ring and terminates at the superficial inguinal ring (this is the path of the testes)
Boundaries of the Inguinal Canal
Anterior Wall- External oblique aponeurosis
Posterior Wall- Transversalis fascia
Roof- Arched fibers of internal oblique (low arched) and transversus abdominis (high arched)
Floor- Inguinal ligament
Transversalis Fascia
- Lines the inner surface of transversus abdominis muscle
- Forms the posterior wall of the inguinal canal
- Represented in scrotum as the internal spermatic fascia
- It has the deep inguinal ring
Deep inguinal ring
Oval opening in the transversalis fascia, just lateral to the inferior epigastric vessels (which share in the inguinal triangle)
What passes through the Deep inguinal ring?
Spermatic cord in males (or round ligament of uterus in females) and genital branch of gentiofemoral nerve to Cremastric muscle
Inguinal Triangle
Aka Hesselbach’s triangle
An area of potential weakness and hence is a common site of a direct inguinal hernia.
BOUNDARIES:
- Medial- Linea semilunaris (lateral edge of the rectus abdominis)
- Lateral- lateral umbilical fold (formed by the inferior epigastric vessels)
- Inferior- Inguinal ligament
Transversus Abdominis
- Forms the Roof of the Inguinal Canal
- NOT REPRESENTED IN SCROTUM due to its high arching fibers
- Most fibers of transversus abdominis muscle run transverse except the High arching fibers, which all originate from the inguinal ligament
What forms the conjoint tendon?
High arching fibers of the transversus abdominis come together with the internal oblique. The tendon descends behind the superficial inguinal ring to be attached to the pubic crest and pectineal line
Internal Oblique
- Forms roof of the Inguinal Canal (together with the transversus abdominis)
- Represented in the Scrotum as the Cremastric Muscle
- All fibers run upward, forward and medial except those which originate from the inguinal ligament– these are low-arching fibers
Triple relation that the lower free arched fibers of the internal oblique has to the spermatic cord
It is anterior, above, and posterior to the spermatic cord (or round ligament in females)
External Oblique
- Forms the anterior wall of the canal
- Fibers run downward, forward, and medially
- Represented in scrotum as the External spermatic fascia
- It has the superficial inguinal ring
Inguinal ligament
- The lower thickened border of the external oblique which I folded upon itself.
- forms the floor of the inguinal canal
- gives partial origin to internal oblique and transversus abdominis (the arching fibers)
Lacunar ligament
Triangular posterior extension from the medial end of inguinal ligament. Connects the inguinal ligament to the pectineal ligament near the point where they both insert on the pubic tubercle.
Superficial inguinal ring
- Triangular opening which lies in the external oblique aponeurosis, superolateral to the pubic crest.
- Pubic crest is its base and its sides are medial and lateral crura
- Supported posteriorly by the conjoint tendon
What runs through the Superficial Inguinal Ring?
Spermatic cord in males (or round ligament of uterus in females) and Ilioinguinal nerve
Path of the Ilioinguinal nerve
(1) Pierces Transversus abdominis to run between it and internal oblique
(2) Then pierces the lower part of internal oblique
(3) Then enters the Inguinal canal to exit through the superficial inguinal ring
Path of the Iliohypogastric nerve through the Inguinal canal.
The Iliohypogastric nerve is NOT in the canal.
The 3 coverings of the Spermatic Cord
(1) External spermatic fascia (from external oblique muscle)
(2) Cremaster muscle/fascia (from internal oblique)
(3) Internal Spermatic Fascia (From transversalis fascia)
The 3 Arteries of the Spermatic Cord
(1) Testicular
(2) Cremastric
(3) Artery of Vas
The 3 V’s of the Spermatic Cord
(1) Vas Deferens
(2) pampiniform Venous plexus
(3) Vestige of processus Vaginalis
The 3 Nerves of the Spermatic Cord
(1) Genital branch of Genitofemoral nerve
(2) Sympathetic Plexus around the Testicular Artery
(3) Sympathetic plexus around the artery of vas
Inguinal Hernia
It is the protrusion of the abdominal contents (usually intestine) within a sac of peritoneum into the inguinal canal. Much more common in males (due to their large canal)
Indirect Inguinal Hernia
- Passes through the deep ring, inguinal canal and superficial ring
- Descends into the scrotum
- Lies lateral to the inferior epigastric artery
- MOST COMMON
- Congenital
Direct Inguinal Hernia
- Pushed through weakened area of the abdominal wall (ie inguinal triangle)
- It is unusual for the direct hernia to reach scrotum
- Lie medial to the inferior epigastric artery
- An acquired hernia
In the suprapubic region, the parietal peritoneum is raised by…
5 folds, via 5 structures which run in the extraperitoneal tissue:
One (1) MediaN umbilical fold
Two (2) MediaL umbilical folds
Two (2) Lateral umbilical folds
Median Umbilical fold
Raised by the median umbilical ligament (houses fibrosed or obliterated Urachus).
Extends from apex of urinary bladder towards the umbilicus
Medial Umbilical folds (2)
Raised by Medial umbilical ligaments (houses obliterated umbilical artery)
Lateral umbilical ligaments (2)
Raised by (houses) the Inferior epigastric arteries on their way to rectus sheath
