The median sacral artery (or middle sacral artery) is a small
artery
An artery (plural arteries) () is a blood vessel in humans and most animals that takes blood away from the heart to one or more parts of the body (tissues, lungs, brain etc.). Most arteries carry oxygenated blood; the two exceptions are the p ...
that arises posterior to the
abdominal aorta and superior to its bifurcation.
Structure
The median sacral artery arises from the
abdominal aorta at the level of the bottom quarter of the
third lumbar vertebra. It descends in the middle line in front of the fourth and fifth
lumbar vertebrae
The lumbar vertebrae are, in human anatomy, the five vertebrae between the rib cage and the pelvis. They are the largest segments of the vertebral column and are characterized by the absence of the foramen transversarium within the transverse ...
, the
sacrum
The sacrum (plural: ''sacra'' or ''sacrums''), in human anatomy, is a large, triangular bone at the base of the spine that forms by the fusing of the sacral vertebrae (S1S5) between ages 18 and 30.
The sacrum situates at the upper, back part ...
and
coccyx
The coccyx ( : coccyges or coccyxes), commonly referred to as the tailbone, is the final segment of the vertebral column in all apes, and analogous structures in certain other mammals such as horses. In tailless primates (e.g. humans and other ...
, ending in the
glomus coccygeum
The coccygeal glomus (coccygeal gland or body; Luschka’s gland) is a vestigial structure placed in front of, or immediately below, the tip of the coccyx.
Anatomy
It is about 2.5 mm. in diameter and is irregularly oval in shape; several sma ...
(coccygeal gland).
Minute branches pass from it, to the posterior surface of the
rectum
The rectum is the final straight portion of the large intestine in humans and some other mammals, and the gut in others. The adult human rectum is about long, and begins at the rectosigmoid junction (the end of the sigmoid colon) at the le ...
.
On the last lumbar vertebra it
anastomoses
An anastomosis (, plural anastomoses) is a connection or opening between two things (especially cavities or passages) that are normally diverging or branching, such as between blood vessels, leaf veins, or streams. Such a connection may be norma ...
with the lumbar branch of the
iliolumbar artery
The iliolumbar artery is the first branch of the posterior trunk of the internal iliac artery.
Structure
The iliolumbar artery is the first branch of the posterior trunk of the internal iliac artery. It turns upward behind the obturator nerve an ...
; in front of the sacrum it anastomoses with the
lateral sacral arteries
The lateral sacral arteries is an artery in the pelvis that arises from the posterior division of the internal iliac artery. It later splits into two smaller branches, a superior and an inferior.
Structure
The lateral sacral artery is the sec ...
, sending offshoots into the
anterior sacral foramina
The sacrum (plural: ''sacra'' or ''sacrums''), in human anatomy, is a large, triangular bone at the base of the spine that forms by the fusing of the sacral vertebrae (S1S5) between ages 18 and 30.
The sacrum situates at the upper, back part ...
.
It is crossed by the left
common iliac vein
In human anatomy, the common iliac veins are formed by the external iliac veins and internal iliac veins. The left and right common iliac veins come together in the abdomen at the level of the fifth lumbar vertebra, forming the inferior vena c ...
and accompanied by a pair of
venae comitantes
Vena comitans is Latin for accompanying vein. It refers to a vein that is usually paired, with both veins lying on the sides of an artery. They are found in close proximity to arteries so that the pulsations of the artery aid venous return. B ...
; these unite to form a single vessel that opens into the left
common iliac vein
In human anatomy, the common iliac veins are formed by the external iliac veins and internal iliac veins. The left and right common iliac veins come together in the abdomen at the level of the fifth lumbar vertebra, forming the inferior vena c ...
.
Development
The median sacral artery is morphologically the direct continuation of the abdominal aorta.
It is
vestigial
Vestigiality is the retention, during the process of evolution, of genetically determined structures or attributes that have lost some or all of the ancestral function in a given species. Assessment of the vestigiality must generally rely on co ...
in humans, but large in animals with tails, such as the
crocodile
Crocodiles (family Crocodylidae) or true crocodiles are large semiaquatic reptiles that live throughout the tropics in Africa, Asia, the Americas and Australia. The term crocodile is sometimes used even more loosely to include all extant mem ...
.
See also
*
Lateral sacral artery
The lateral sacral arteries is an artery in the pelvis that arises from the posterior division of the internal iliac artery. It later splits into two smaller branches, a superior and an inferior.
Structure
The lateral sacral artery is the seco ...
Additional images
File:Gray586.png, The iliac veins.
File:Gray587.png, Scheme of the anastomosis of the veins of the rectum.
File:Gray1120.png, The relations of the viscera and large vessels of the abdomen.
File:Slide12y.JPG, Median sacral artery
File:Slide2ERVA.JPG, Pelvic contents: male. Superior view. Deep dissection.
References
External links
* - "Posterior Abdominal Wall: Branches of the Abdominal Aorta"
* ()
{{Authority control
Arteries of the abdomen