The rectus sheath, also called the rectus fascia,. is formed by the

aponeuroses An aponeurosis (; plural: ''aponeuroses'') is a type or a variant of the deep fascia, in the form of a sheet of pearly-white fibrous tissue that attaches sheet-like muscles needing a wide area of attachment. Their primary function is to join muscl ...

of the

transverse abdominal The transverse abdominal muscle (TVA), also known as the transverse abdominis, transversalis muscle and transversus abdominis muscle, is a muscle layer of the anterior and lateral (front and side) abdominal wall which is deep to (layered below) t ...

and the

internal Internal may refer to: *Internality as a concept in behavioural economics *Neijia, internal styles of Chinese martial arts *Neigong or "internal skills", a type of exercise in meditation associated with Daoism *''Internal (album)'' by Safia, 2016 ...

and

external oblique muscle The abdominal external oblique muscle (also external oblique muscle, or exterior oblique) is the largest and outermost of the three flat abdominal muscles of the lateral anterior abdomen. Structure The external oblique is situated on the lateral ...

s. It contains the

rectus abdominis The rectus abdominis muscle, ( la, straight abdominal) also known as the "abdominal muscle" or simply the "abs", is a paired straight muscle. It is a paired muscle, separated by a midline band of connective tissue called the linea alba. It exte ...

and pyramidalis muscles.

Structure

The rectus sheath can be divided into anterior and posterior laminae. The arrangement of the layers has important variations at different locations in the body.

Below the costal margin

For context, above the sheath are the following two layers: # Camper's fascia (anterior part of Superficial fascia) #

Scarpa's fascia The fascia of Scarpa is the deep membranous layer ''(stratum membranosum)'' of the superficial fascia of the abdomen. It is a layer of the anterior abdominal wall. It is found ''deep'' to the fascia of Camper and ''superficial'' to the extern ...

(posterior part of the Superficial fascia) Within the sheath, the layers vary: Below the sheath are the following three layers: #

transversalis fascia The transversalis fascia (or transverse fascia) is a thin aponeurotic membrane of the abdomen. It lies between the inner surface of the transverse abdominal muscle and the parietal peritoneum. It forms part of the general layer of fascia lining ...

extraperitoneal fat Between the inner surface of the general layer of the fascia which lines the interior of the abdominal and pelvic cavities, and the peritoneum, there is a considerable amount of connective tissue, termed the extraperitoneal fat or subperitoneal ...

parietal peritoneum The peritoneum is the serous membrane forming the lining of the abdominal cavity or coelom in amniotes and some invertebrates, such as annelids. It covers most of the intra-abdominal (or coelomic) organs, and is composed of a layer of mesothel ...

The rectus, in the situation where its sheath is deficient below, is separated from the

peritoneum The peritoneum is the serous membrane forming the lining of the abdominal cavity or coelom in amniotes and some invertebrates, such as annelids. It covers most of the intra-abdominal (or coelomic) organs, and is composed of a layer of mesoth ...

only by the

, in contrast to the upper layers, where part of the internal oblique also runs beneath the rectus. Because of the thinner layers below, this region is more susceptible to

herniation A hernia is the abnormal exit of tissue or an organ, such as the bowel, through the wall of the cavity in which it normally resides. Various types of hernias can occur, most commonly involving the abdomen, and specifically the groin. Groin hernia ...

Above the costal margin

Since the tendons of the internal oblique and transversus abdominis only reach as high as the

costal margin The costal margin, also known as the costal arch, is the lower edge of the chest (thorax) formed by the bottom edge of the rib cage. Structure The costal margin is the medial margin formed by the cartilages of the seventh to tenth ribs. It attac ...

, it follows that above this level the sheath of the rectus is deficient behind, the muscle resting directly on the cartilages of the ribs, and being covered only by the tendons of the external obliques.

Clinical significance

The rectus sheath is a useful attachment for surgical meshes during

abdominal surgery The term abdominal surgery broadly covers surgical procedures that involve opening the abdomen (laparotomy). Surgery of each abdominal organ is dealt with separately in connection with the description of that organ (see stomach, kidney, liver, etc ...

. This has a higher risk of

infection An infection is the invasion of tissues by pathogens, their multiplication, and the reaction of host tissues to the infectious agent and the toxins they produce. An infectious disease, also known as a transmissible disease or communicable dise ...

than many other attachment sites.

Additional images

File:Gray396.png, The Cremaster File:Gray398.png, The interfoveolar ligament, seen from in front.

References

External links

* - "Incisions and the contents of the rectus sheath." * - "Anterior Abdominal Wall: The Rectus Abdominis Muscle" * - anterior layer * - posterior layer above arcuate line * - posterior layer above arcuate line * * - "The Rectus Sheath, Anterior View & Transverse Section" {{Authority control Abdomen Muscles of the torso