Abdominal external oblique muscle

This article needs additional citations for verification. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed. Find sources: "Abdominal external oblique muscle" – news · newspapers · books · scholar · JSTOR (August 2017) (Learn how and when to remove this template message)

Abdominal external oblique muscle
Ribs 5-12
Insertion	Xiphoid process, outer lip of the iliac crest, pubic crest, pubic tubercle, linea alba, inguinal ligament, anterior superior iliac spine (ASIS)
Nerve	Thoraco-abdominal nerves (T7-11) and subcostal nerve (T12)
Actions	Flexion of the torso and contralateral rotation of torso
Identifiers
Latin	musculus obliquus externus abdominis
TA98	A04.5.01.008
TA2	2364
FMA	13335
Anatomical terms of muscle [edit on Wikidata ]

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 and anterior parts of the

deposits and the small size of the muscle.

It arises from eight fleshy digitations, each from the external surfaces and inferior borders of the fifth to twelfth ribs (lower eight ribs). These digitations are arranged in an oblique line which runs inferiorly and anteriorly, with the upper digitations being attached close to the cartilages of the corresponding ribs, the lowest to the apex of the cartilage of the last rib, the intermediate ones to the ribs at some distance from their cartilages.

The five superior serrations increase in size from above downward, and are received between corresponding processes of the

. From these attachments the fleshy fibers proceed in various directions. Its posterior fibers from the ribs to the iliac crest form a free posterior border.

Those from the lowest ribs pass nearly vertically downward, and are inserted into the anterior half of the outer lip of the

.

The

.

The internal oblique muscle is just deep to the external oblique muscle.^[1]

Nerve supply

The external oblique muscle is supplied by ventral branches of the lower six thoracoabdominal nerves and the subcostal nerve on each side.

Blood supply

The cranial portion of the muscle is supplied by the lower intercostal arteries, whereas the caudal portion is supplied by a branches of either the deep circumflex iliac artery or the iliolumbar artery.

Function

The external oblique functions to pull the chest downwards and compress the abdominal cavity, which increases the intra-abdominal pressure as in a Valsalva maneuver. It also performs ipsilateral (same side) side-bending and contralateral (opposite side) rotation: the right external oblique would side-bend to the right and rotate to the left, and vice versa. The internal oblique muscle functions similarly except it rotates ipsilaterally.

Society and culture

Oblique strain

The oblique strain is a common baseball injury, particularly in pitchers. In both batters and pitchers it can affect the contralateral (leading) side external oblique, or the trailing internal oblique.^[2]

Training

• Side plank

Additional images

• 
  Posterior view of muscles connecting the upper extremity to the vertebral column. Posterior part of abdominal external oblique muscle labeled.
• 
  The subcutaneous inguinal ring.
• 
  Transverse section through the middle of the first lumbar vertebra, showing the relations of the pancreas.
• 
  The left side of the thorax.
• 
  Surface anatomy of the front of the thorax and abdomen.
• 
  Lumbar triangle
• 
  External abdominal oblique muscle. Anterior abdominal wall. Deep dissection. Anterior view.

References

This article incorporates text in the public domain from page 409 of the 20th edition of Gray's Anatomy (1918)

External links

• Anatomy image:7061 at the SUNY Downstate Medical Center
• Cross section image: pembody/body8a—Plastination Laboratory at the Medical University of Vienna