and Edgar D. Guzman-Arrieta3
(1)
Department of Surgery Advocate Illinois Masonic Medical Center, University of Illinois Metropolitan Group Hospitals Residency in General Surgery, Chicago, IL, USA
(2)
University of Illinois at Chicago, Chicago, IL, USA
(3)
Vascular Specialists – Hattiesburg Clinic, Hattiesburg, MS, USA
Keywords
Abdominal wallHerniaPreperitoneal spaceInguinal canalInguinal ligamentMyopectineal orificeHernia repair1.
The following are true statements in relation to the linea alba except
(a)
The fibers coming from the oblique and transversus abdominis muscles do not cross the midline.
(b)
The linea alba gains considerable strength through the interlocking of collagen fibers.
(c)
The linea alba widens with increasing age.
(d)
The width of the linea alba varies with the angle of the costal arches.
(e)
Transverse incisions have greater bursting strength than vertical incisions.
Comments
Among vertical incisions, midline incisions are the strongest by virtue of the anatomy of the linea alba. The linea alba represents the fusion of the aponeurotic envelopes of the external oblique, internal oblique, and transversus abdominis, by decussation, condensation, and interlocking of collagen fibers. The linea alba extends from the xiphoid process to the pubic symphysis. Its extensively decussated collagen fibers are oriented in oblique direction, making it resistant to tension in this plane, and at the same time making it compliant to longitudinal stretching. As one moves away from the linea alba into the rectus sheath, the gridiron of decussating fibers becomes looser, which determines the decreased strength of paramedian incisions [1,2].
The orientation of collagen fibers in the abdominal wall gives transverse incisions the theoretical advantage of minimizing structural damage, lending greater bursting strength when compared to midline incisions. In clinical practice, transverse incisions have been associated with lower incidence of wound dehiscence and incisional hernia, as well as with decreased postoperative pain pulmonary complications when compared to midline incisions [3]. However, more recent meta-analysis challenges these claims [4].
The width of the linea alba can be predicted by the angle of the costal arch. People with wide costal arches generally have a wider linea alba and vice versa.
Answer
a
2.
All of the following are correct except:
(a)
The femoral artery provides the blood supply of the anterior aspect of the inferior abdominal wall.
(b)
The lower intercostal and lumbar arteries constitute a deep system supplying the oblique muscles and the transversus abdominis.
(c)
The rectus abdominis muscles receive their blood supply from the superior and inferior epigastric arteries.
(d)
The rectus abdominis muscle has segmental innervation, which allows its transection with subsequent preservation of function.
(e)
The rectus abdominis muscle should be retracted from lateral to medial to avoid disturbing the musculocutaneous nerves.
Comments
The blood supply of the abdominal wall is multiple. The descending aorta directly contributes to the blood supply of the abdominal wall through the lower intercostal arteries and the analogous lumbar arteries. The femoral artery contributes to the blood supply of the lower abdominal wall through the superficial circumflex, superficial epigastric, and external pudendal branches.
The rectus abdominis muscles have a dual blood supply that runs posterior to the muscle. Cephalad, the superior epigastrics, which are a continuation of the internal mammaries, travel caudally to anastomose with the inferior epigastrics which branch off the external iliac arteries at the level of the inguinal ligament. Throughout their course, these arteries send branches anteriorly, which enter the substance of the muscle. These branches continue their anterior course through the muscle to supply the skin and subcutaneous tissues of the area, allowing the creation of musculocutaneous flaps based on the epigastric arteries.
The rectus muscle has a complex embryologic origin from multiple dermatomes spanning T6–T12, with the umbilicus at T10 level. It is not clear whether the transverse intersections of the rectus abdominis represent divisions between the myotomes that give origin to the muscle or if they arise independently. In any case, the transverse disposition of nerve fibers allows the muscle to be transected without denervation. In paramedian incisions, the rectus muscle should always be retracted laterally to keep an intact nerve supply [1].
Answer
e
3.
Mark the false statement in relation to the layers of the abdominal wall and scrotum.
(a)
Scarpa’s fascia becomes the dartos layer of the scrotum.
(b)
The external oblique fascia is continuous with the external spermatic fascia.
(c)
The internal oblique muscle fibers are continuous with the cremaster muscle and fascia.
(d)
The transversus abdominis muscle is continuous with the internal spermatic fascia.
(e)
The parietal peritoneum is continuous with the processus vaginalis.
Comments
The layers of the scrotum are continuous with the layers of the abdominal wall. These are shown in Table 8.1 and Fig. 8.1.
Table 8.1
The layers of the scrotum are continuous with the layers of the abdominal wall
Layer of the abdominal wall | Layer of the scrotum |
|---|---|
Skin | Skin |
Scarpa’s fascia | Dartos |
External oblique fascia | External spermatic fascia |
Internal oblique muscle | Cremaster |
Fascia transversalis | Internal spermatic fascia |
Peritoneum | Tunica vaginalis |
Fig. 8.1
As the normal testicles descend from their retroperitoneal embryonic origin to the anteriorly situated scrotal sac to maintain lower temperature for spermatogenesis, they bring along a thin covering of each layer of the abdominal wall progressively from the deep inguinal ring past the superficial inguinal ring. Testicles, even though enveloped by a knuckle of the double layer of the peritoneum, continue to be extraperitoneal. The vas deferens, spermatic vessels, and lymphatics continue to drain into their respective preperitoneal and retroperitoneal target organs
As can be noted in Table 8.1, the transversus abdominis muscle does not contribute to the layers of the scrotum.
The classical view describes the testicles as arising in the retroperitoneum, without peritoneal coverage. As they descend into the scrotum, the peritoneum evaginates, forming the bilayered tunica vaginalis. This tunica travels anterior to the testicle and eventually surrounds the testicle with exception of its posterior aspect. However, the testicle remains extraperitoneal.
Answer
d
4.
The following structures define the boundaries of the myopectineal orifice except:
(a)
Inferior border of the internal oblique
(b)
Inguinal ligament
(c)
Iliopsoas muscle
(d)
Lateral border of the rectus abdominis
(e)
Superior edge of the superior pubic ramus
Comments
See question 7.
Answer
b
5.
The following structures define the boundaries of the inguinal canal except:
(a)
Cooper’s ligament
(b)
External oblique aponeurosis
(c)
Transversus abdominis aponeurosis and transversalis fascia
(d)
Inferior edge of the internal oblique
(e)
Inguinal ligament
Comments
See question 7.
Answer
a
6.
The following statements are correct except:
(a)
In laparoscopic and open repair, prosthetic material is ideally placed in the preperitoneal space.
(b)
The inguinal ligament (ligament of Poupart) is the thickened inferior edge of the external oblique aponeurosis.
(c)
Intraparietal hernias should always be sought in an inguinal hernia repair.
(d)
The lacunar ligament (ligament of Gimbernat) joins the medial aspect of the inguinal ligament to the pubic symphysis.
(e)
The pectineal ligament (Cooper’s ligament) is the thickened periosteum of the superior pubic ramus.
Comments
See question 7.
Answer
d
7.
The following structures define the femoral ring except:
(a)
Femoral vein
(b)
Cooper’s ligament
(c)
Inguinal ligament
(d)
Lacunar ligament
(e)
Pubic tubercle
Comments
The myopectineal orifice represents an opening through the anterior abdominal wall that allows the passage of the spermatic cord and of the femoral vessels and nerve. It is limited laterally by the iliopsoas muscle, medially by the edge of the rectus sheath, superiorly by the edge of the internal oblique, and inferiorly by Cooper’s ligament. The inguinal ligament divides the myopectineal orifice into the inguinal region superiorly and the femoral region inferiorly.
The inguinal ligament and its shelving edge form the lower boundary of the inguinal canal, with the upper border provided by the free edge of the internal oblique muscle. The roof (ventral) of the inguinal canal is formed by the external oblique aponeurosis, and the floor (dorsal) is formed by the transversus abdominis aponeurosis reinforced by the transversalis fascia [5].
The transversus abdominis aponeurosis is not to be confused with the transversalis fascia, although both structures may be fused together. The former is the fibrous extension of the transversus abdominis muscle, as it extends towards the midline and pubic tubercle, whereas the latter is a part of the endoabdominal fascia, which lines all the walls of the abdomen, including the diaphragm and pelvis [6].
The inguinal canal extends from the internal (deep and lateral) inguinal ring to the external (superficial and medial) inguinal ring. In the newborn, these two rings overlie each other, allowing the passage of the testicle into the scrotum. During growth to adulthood, the two rings separate with the superficial ring overlying the pubic tubercle and the deep ring located at the mid-inguinal point. The deep inguinal ring is located in the transversalis fascia and transversus abdominis muscle. It vests the internal spermatic fascia on the structures traversing it. The superficial ring is located in the external oblique aponeurosis and provides the external spermatic fascia vesting any structure going through this opening [7] (Fig. 8.2).
Fig. 8.2
Illustrated is a diagrammatic representation of the floor of the inguinal canal and the cross-sections of the spermatic cord in indirect and direct inguinal hernias. The deep or internal inguinal ring lies in the transversalis fascia, bounded medially by the deep inferior epigastric artery and vein. An indirect hernia sac is often accompanied by herniated fat from the preperitoneal space erroneously called the lipoma of the cord. Any structure which comes through the deep ring is enveloped by the internal spermatic fascia, which is a continuation of a thin fascia from the transversalis that must be incised to get to the hernia sac. Direct hernias protrude directly from the floor of the inguinal canal, medial to the deep inferior epigastric vessels. The preperitoneal space carries varying amounts of fat and continues laterally and posteriorly into the retroperitoneal space
The variability of the inguinal region has led to some semantic confusion with multiple names attached to the same structures depending on surgical exposure.
The femoral canal lies medial to the femoral vein, normally containing a small amount of fat and the lymph node of Cloquet. Its medial aspect is the lacunar ligament (ligament of Gimbernat), which is a collection of fibers arising from the inguinal ligament, inserting on the medial aspect of the superior pubic ramus, close to the pubic tubercle. These fibers may be incised when attempting to release an incarcerated femoral hernia. Its ventral margin is the inguinal ligament, and its posterior margin is Cooper’s ligament. Because of the tight and fixed boundaries of the femoral ring, femoral hernias are more likely to strangulate than inguinal hernias [8].
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