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27 Cards in this Set
- Front
- Back
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Anterolateral Abdominal wall |
Although the abdominal wall is continuous, it is subdivided into the anterior wall, right and left lateral walls, and posterior wall for descriptive purposes .
The wall is musculoaponeurotic, except for the posterior wall, which includes the lumbar region of the vertebral column.
The boundary between the anterior and the lateral walls is indefinite, therefore the term anterolateral abdominal wall is often used.
Some structures, such as muscles and cutaneous nerves, are in both the anterior and lateral walls.
The anterolateral abdominal wall extends from the thoracic cage to the pelvis.
The anterolateral abdominal wall is bounded superiorly by the cartilages of the 7th–10th ribs and the xiphoid process of the sternum, and
inferiorly by the inguinal ligament and the superior margins of the anterolateral aspects of the pelvic girdle (iliac crests, pubic crests, and pubic symphysis) |
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Layers of abdominal wall |
The anterolateral abdominal wall consists of
skin
subcutaneous tissue (superficial fascia) composed mainly of fat, muscles and their aponeuroses
deep fascia,
extraperitoneal fat,
parietal peritoneum .
The skin attaches loosely to the subcutaneous tissue, except at the umbilicus, where it adheres firmly.
Most of the anterolateral wall includes three musculotendinous layers;
the fiber bundles of each layer run in different directions.
This three-ply structure is similar to that of the intercostal spaces in the thorax. |
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Fasciae of Anteriolateral Abdominal wall |
The subcutaneous tissue over most of the wall includes a variable amount of fat.
It is a major site of fat storage. Males are especially susceptible to subcutaneous accumulation of fat in the lower anterior abdominal wall.
In morbid obesity, the fat is many inches thick, often forming one or more sagging folds (L. panniculi; singular = panniculus, apron).
Superior to the umbilicus, the subcutaneous tissue is consistent with that found in most regions.
Inferior to the umbilicus, the deepest part of the subcutaneous tissue is reinforced by many elastic and collagen fibers, so it has two layers:
the superficial fatty layer (Camper fascia) and the deep membranous layer(Scarpa fascia) of subcutaneous tissue.
The membranous layer continues inferiorly into the perineal region as the superficial perineal fascia (Colles fascia), but not into the thighs.
Investing Fasciae
Superficial, intermediate, and deep layers of investing fascia cover the external aspects of the three muscle layers of the anterolateral abdominal wall and their aponeuroses (flat expanded tendons) and cannot be easily separated from them.
The investing fascias here are extremely thin, being represented mostly by the epimysium (outer fibrous connective tissue layer surrounding all muscles—see Introduction) superficial to or between muscles.
The internal aspect of the abdominal wall is lined with membranous and areolar sheets of varying thickness called the endoabdominal fascia. Although continuous, different parts of this fascia are named according to the muscle or aponeurosis it is lining.
The portion lining the deep surface of the transversus abdominis muscle and its aponeurosis is the the transversalis fascia.
The glistening lining of the abdominal cavity, the parietal peritoneum, is formed by a single layer of epithelial cells and supporting connective tissue.
The parietal peritoneum is internal to the transversalis fascia and is separated from it by a variable amount of extraperitoneal fat. |
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Origin |
Internal surfaces of 7th–12th costal cartilages,
thoracolumbar fascia, iliac crest, and connective tissue deep to lateral third of inguinal ligament |
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Origin |
Internal surfaces of 7th–12th costal cartilages, thoracolumbar fascia, iliac crest, and connective tissue deep to lateral third of inguinal ligament |
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Enumerate the muscles of Aneteriolateral Andominal wall |
1)External oblique muscle 2)Internal oblique Muscle 3) Transeverse Abdominalis muscle 4) Rectus Abdominalis muscle 5) pyramidlis |
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Rectus sheath |
The rectus sheath is the strong, incomplete fibrous compartment of the rectus abdominis and pyramidalis muscles.
Also found in the rectus sheath are the superior and inferior epigastric arteries and veins, lymphatic vessels, and distal portions of the thoracoabdominal nerves (abdominal portions of the anterior rami of spinal nerves T7–T12).
The rectus sheath is formed by the decussation and interweaving of the aponeuroses of the flat abdominal muscles.
The external oblique aponeurosis contributes to the anterior wall of the sheath throughout its length.
The superior two thirds of the internal oblique aponeurosis splits into two layers (laminae) at the lateral border of the rectus abdominis;
one lamina passing anterior to the muscle and the other passing posterior to it.
The anterior lamina joins the aponeurosis of the external oblique to form the anterior layer of the rectus sheath.
The posterior lamina joins the aponeurosis of the transversus abdominis to form the posterior layer of the rectus sheath.
Beginning approximately one third of the distance from the umbilicus to the pubic crest, the aponeuroses of the three flat muscles pass anterior to the rectus abdominis to form the anterior layer of the rectus sheath, leaving only the relatively thin transversalis fascia to cover the rectus abdominis posteriorly.
A crescentic arcuate line demarcates the transition between the aponeurotic posterior wall of the sheath covering the superior three quarters of the rectus and the transversalis fascia covering the inferior quarter.
Throughout the length of the sheath, the fibers of the anterior and posterior layers of the sheath interlace in the anterior median line to form the complex linea alba.
The posterior layer of the rectus sheath is also deficient superior to the costal margin because the transversus abdominis is continued superiorly as the transversus thoracis, which lies internal to the costal cartilages and the internal oblique attaches to the costal margin.
Hence, superior to the costal margin, the rectus abdominis lies directly on the thoracic wall |
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Linea Alba |
The linea alba, running vertically the length of the anterior abdominal wall and separating the bilateral rectus sheaths. narrows inferior to the umbilicus to the width of the pubic symphysis and widens superiorly to the width of the xiphoid process. The linea alba transmits small vessels and nerves to the skin. In thin muscular people, a groove is visible in the skin overlying the linea alba. At its middle, underlying the umbilicus, the linea alba contains the umbilical ring, a defect in the linea alba through which the fetal umbilical vessels passed to and from the umbilical cord and placenta. All layers of the anterolateral abdominal wall fuse at the umbilicus. As fat accumulates in the subcutaneous tissue postnatally, the skin becomes raised around the umbilical ring and the umbilicus becomes depressed. This occurs 7–14 days after birth, when the atrophic umbilical cord “falls off.” |
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Functions of Anterolateral Abdominal muscles |
CSSM •Compress the abdominal contents to maintain or increase the intra-abdominal pressure and, in so doing, oppose the diaphragm (increased intra-abdominal pressure facilitates expulsion). • strong expandable support for the anterolateral abdominal wall. •Support the abdominal viscera and protect them from most injuries. •Move the trunk and help to maintain posture. |
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Enumerate nerves of the Anterolateral abdominal wall |
1) Thoracoabdominal nerve 2)latera cutnaous nerve 3)subcostal nerves 4)illiohypgastric nerve 5)illioinguinal nerve |
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Thorcoabdominal nerve |
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Lateral cutaneous nerve |
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Subcostal nerve |
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All about External oblique muscle |
The external oblique muscle is the largest and most superficial of the three flat anterolateral abdominal muscles .
In contrast to the two deeper layers, the external oblique does not originate posteriorly from the thoracolumbar fascia;
its posteriormost fibers (the thickest part of the muscle) have a free edge where they span between its costal origin and the iliac crest
Fleshy part contributes to the lateral wall in contrast apaneuratic part contributes in the formation of anterior abdominal wall.
Although the posteriormost fibers from rib 12 are nearly vertical as they run to the iliac crest, more anterior fibers fan out, taking an increasingly medial direction so that most of the fleshy fibers run inferomedially—in the same direction as the fingers do when the hands are in one’s side pockets—with the most anterior and superior fibers approaching a horizontal course.
The muscle fibers become aponeurotic approximately at the MCL medially and at the spinoumbilical line (line running from the umbilicus to the ASIS) inferiorly, forming a sheet of tendinous fibers that decussate at the linea alba, most becoming continuous with tendinous fibers of the contralateral internal oblique .
Thus the contralateral external and internal oblique muscles together form a “digastric muscle,” a two-bellied muscle sharing a common central tendon that works as a unit (see Introduction chapter).
For example, the right external oblique and left internal oblique work together when flexing and rotating to bring the right shoulder toward the left hip (torsional movement of trunk).
Inferiorly, the external oblique aponeurosis attaches to the pubic crest medial to the pubic tubercle.
The inferior margin of the external oblique aponeurosis is thickened as an undercurving fibrous band with a free posterior edge that spans between the ASIS and the pubic tubercle as the inguinal ligament (Poupart ligament)
Palpate your inguinal ligament by pressing deeply into the center of the crease between the thigh and trunk and moving the fingertips up and down.
Inferiorly the inguinal ligament is continuous with the deep fascia of the thigh.
The inguinal ligament is therefore not a freestanding structure, although—as a useful landmark—it is frequently depicted as such.
It serves as a retinaculum (retaining band) for the muscular and neurovascular structures passing deep to it to enter the thigh.
The inferior parts of the two deeper anterolateral abdominal muscles arise in relationship to the lateral portion of the inguinal ligament. |
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IOM Introduction |
The intermediate of the three flat abdominal muscles, the internal oblique is a thin muscular sheet that fans out anteromedially.
Except for its lowermost fibers, which arise from the lateral half of the inguinal ligament,
its fleshy fibers run perpendicular to those of the external oblique, running superomedially (like your fingers when the hand is placed over your chest).
Its fibers also become aponeurotic at the MCL and participate in the formation of the rectus sheath.
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Origin |
Thoracolumbar fascia, anterior two thirds of iliac crest, and connective tissue deep to lateral third of inguinal ligament |
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Insertion |
Inferior borders of 10th–12th ribs, linea alba, and pecten pubis via conjoint tendon |
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Innervation |
Thoracoabdominal nerves (anterior rami of T6–T12 spinal nerves) and first lumbar nerves |
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Action |
Have two functions a) Compresses and supports abdominal viscera, b) flexes and rotates trunk |
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Transverse Abdominalis muscle |
The fibers of the transversus abdominis, the innermost of the three flat abdominal muscles run more or less transversally, except for the inferior ones, which run parallel to those of the internal oblique.
This transverse, circumferential orientation is ideal for compressing the abdominal contents, increasing intra-abdominal pressure.
The fibers of the transversus abdominis muscle also end in an aponeurosis, which contributes to the formation of the rectus sheath.
The attachments of the transversus abdominis are Between the internal oblique and the transversus abdominis muscles is a neurovascular plane, lie mostly in the subcutaneous tissue. |
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Insertion |
Linea alba with aponeurosis of internal oblique, pubic crest, and pecten pubis via conjoint tendon |
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Innervation |
Thoracolumar nerves Anterior rami of T6-T12 and first lumbar nerve |
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Action |
Compression and support of Abdominal viscera. |
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Rectus Abdominalis muscle |
A long, broad, strap-like muscle, the rectus abdominis (L. rectus, straight) is the principal vertical muscle of the anterior abdominal wall . The paired rectus muscles, separated by the linea alba, lie close together inferiorly. The rectus abdominis is three times as wide superiorly as inferiorly; it is broad and thin superiorly and narrow and thick inferiorly. Most of the rectus abdominis is enclosed in the rectus sheath. The rectus muscle is anchored transversely by attachment to the anterior layer of the rectus sheath at three or more tendinous intersections When tensed in muscular people, the areas of muscle between the tendinous intersections bulge outward. The intersections, indicated by grooves in the skin between the muscular bulges, usually occur at the level of the xiphoid process, umbilicus, and halfway between these structures. |
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Pyramidalis |
The pyramidalis is a small, insignificant triangular muscle that is absent in approximately 20% of people. It lies anterior to the inferior part of the rectus abdominis and attaches to the anterior surface of the pubis and the anterior pubic ligament. It ends in the linea alba, which is especially thickened for a variable distance superior to the pubic symphysis. The pyramidalis tenses the linea alba. When present, surgeons use the attachment of the pyramidalis to the linea alba as a landmark for median abdominal incision |
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Illiohypogastric nerve |
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Illioingunal nerve |
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