Anterolateral Abdominal Wall and Groin

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32
Anterolateral Abdominal Wall and Groin


The abdomen is the part of the trunk that lies between the diaphragm and pelvis. The abdominal and pelvic cavities are continuous, and the abdominal cavity is lined by a serous membrane (peritoneum, see Chapters 33 and 34) and contains most of the organs of the digestive system.


From superficial to deep, the layers covering the anterior and lateral aspects of the abdomen are skin, subcutaneous tissue, muscles or fascia, extraperitoneal tissue, and peritoneum (Table 32.1). This multilayered musculofascial organization contributes to the anatomy of the groin. During embryologic descent of the male gonads, these layers are drawn inferiorly and contribute to formation of the spermatic cord and scrotum.


TABLE 32.1 Anterolateral Abdominal Wall—Layers and Derivatives








































Anterior Abdominal Wall Layers


Scrotal Layers


Inguinal Canal


1 Skin


Skin


 


2 Superficial fascia


Dartos fascia and muscle


 


3 External abdominal oblique muscle/aponeurosis


External spermatic fascia


Superficial inguinal ring, anterior wall, floor—inguinal and lacunar ligaments


4 Internal abdominal oblique muscle/aponeurosis


Cremaster muscle


Roof and posterior wall via conjoint tendon


5 Transversus abdominis muscle


Cremaster muscle


 


6 Transversalis fascia


Internal spermatic fascia


Deep inguinal ring and posterior wall


7 Extraperitoneal connective tissue/fat


Fat


 


8 Peritoneum


Tunica vaginalis


 


Structural support for the abdominal region is provided superiorly by the inferior margin of the rib cage, anteriorly by the muscles of the anterior abdominal wall, inferiorly by the pelvic girdle and pelvic diaphragm (see Chapter 36), and posteriorly by the vertebral column, ribs, and back muscles.


Muscles


The anterior abdominal wall contains the rectus abdominis muscle, which is a long muscle in the midline that flexes the trunk and extends from the inferior rib cage to the pelvic inlet. The rectus abdominis is covered by several layers of fascia derived from three anterolateral abdominal muscles (Fig. 32.1).


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FIGURE 32.1 Anterior abdominal wall muscles.


The anterolateral abdominal wall is composed of three sheet-like muscles (Table 32.2): an outer external oblique, a middle internal oblique, and an inner transversus abdominis muscle (see Fig. 32.1). Anteriorly, these muscles become aponeurotic, fuse, and form a sheath around the rectus abdominis muscle. They rotate and flex the trunk anteriorly and laterally and assist in expiration, coughing, vomiting, and defecation.


TABLE 32.2 Muscles of the Anterolateral Abdominal Wall


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The rectus sheath (Table 32.3), formed by the anterolateral abdominal muscle aponeurosis, contains the superior and inferior epigastric vessels, the segmental thoraco-abdominal nerves (T7 to T11), the subcostal (T12) nerves, and lymphatic vessels.


TABLE 32.3 Components of the Rectus Sheath














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Jun 11, 2016 | Posted by in ANATOMY | Comments Off on Anterolateral Abdominal Wall and Groin
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    Level


    Anterior Wall


    Posterior Wall


    Above costal margin


    Aponeurosis of external oblique muscle


    Costal cartilages


    Costal margin to lower image of sheath


    Aponeurosis of external oblique muscle, anterior lamina of internal oblique muscle