AskDefine | Define rectus

Dictionary Definition

rectus n : any of various straight muscles [also: recti (pl)]

User Contributed Dictionary

English

Etymology

From the phrase "(musculus) rectus", or "a straight (muscle)".
Rectus therefore means straight in latin.

Noun

  1. Any of several straight muscles in various parts of the body, as of the abdomen, thigh, eye etc.

Latin

Adjective

  1. straight
  2. right
  3. proper, honest

Extensive Definition

The rectus abdominis muscle (commonly known as "abs") is a paired muscle running vertically on each side of the anterior wall of the human abdomen (and in some other animals). There are two parallel muscles, separated by a band of connective tissue called the linea alba (white line). It extends from the pubic symphysis/pubic crest inferiorly to the xiphisternum/xiphoid process and lower costal cartilages (5-7) superiorly.
It is contained in the Rectus sheath.
The rectus is crossed by three fibrous bands called the tendinous inscriptions. Colloqiual names for the appearance of a well-defined rectus abdominis include a six pack and "washboard abs".

Function

The rectus abdominis is a key postural muscle. It is responsible for flexing the lumbar spine, as when doing a 'crunch'. The rectus abdominis can play a role in respiration in the event the patient is short of breath.

Blood supply

A Mathes and Nahai Type III muscle (2 dominant pedicles)
1 - The inferior epigastric artery and vein (or veins) run superiorly on the posterior surface of the rectus abdominis, enter the rectus fascia at the arcuate line, and help to supply the muscle with blood.
2 - superior epigastric artery ( a terminal branch of the internal thoracic)
Also has small segmental contribution from lower 6 intercostal arteries

Location

The Rectus abdominis is a long flat muscle, which extends along the whole length of the front of the abdomen, and is separated from its fellow of the opposite side by the linea alba. It is much broader, but thinner, above than below, and arises by two tendons;
  • the lateral or larger is attached to the crest of the pubis,
  • the medial interlaces with its fellow of the opposite side, and is connected with the ligaments covering the front of the symphysis pubis.
The muscle is inserted by three portions of unequal size into the cartilages of the fifth, sixth, and seventh ribs.
The upper portion, attached principally to the cartilage of the fifth rib, usually has some fibers of insertion into the anterior extremity of the rib itself.
Some fibers are occasionally connected with the costoxiphoid ligaments, and the side of the xiphoid process.

Animals

The Rectus Abdominis is similar in most vertebrates. The most obvious difference between animal and human abdominal musculature is that in animals, there are a different number of tendinous intersections.

Additional images

thorax. Image:Illu trunk muscles.jpg|Muscles of the trunk

External links

  • - "Muscles of the anterior chest wall with the pectoralis major muscles removed."
  • - "Thoracic Wall: The Anterior Thoracic Wall"
  • - "Incision and reflection of the external abdominal oblique muscle."
  • - "Incision and reflection of the internal abdominal oblique muscle."
  • - "Anterior Abdominal Wall: The Rectus Abdominis Muscle"
rectus in German: Musculus rectus abdominis
rectus in Spanish: Recto mayor del abdomen
rectus in Hebrew: שריר הבטן הישר
rectus in Italian: Muscolo retto dell'addome
rectus in Latin: Musculus rectus abdominis
rectus in Dutch: Musculus rectus abdominis
rectus in Japanese: 腹直筋
rectus in Polish: Mięsień prosty brzucha
rectus in Portuguese: Músculo reto do abdome
rectus in Slovenian: Prema trebušna mišica
rectus in Finnish: Vatsalihakset#Suorat_vatsalihakset
rectus in Swedish: Rectus abdominis
rectus in Chinese: 腹直肌
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