Anatomy and fysiology of anorectum
-
the rectum with the anal canal forms the last section of
the colon. It is located in the small pelvis. It is 12-16 cm long and about 4
cm wide. The filled rectum is triple-laterally curved (anteroposterior view),
and double-axial curved anteroposteriorly (lateral view). The lateral curvature
is due to a sharper carving on the right side of the rectum. In the middle of
its length, at the point of the Kohlrausch's fold, at the base of which
is the thickened circular muscle, against this carving the rectum curves to the
left, above and below it to the right
Anteroposterior double
curvature:
- flexura
sacralis – in the cranial three-quarters of the length of the
rectum parallel to the curvature of the sacrum and the skeleton (convexity
backwards);
- flexura
perinealis – at the beginning, the last fifth to a quarter of
the length, bending the rectum at and below the tip of the coccyx
backwards towards the anal opening (rectum convexity forward);
Two main
parts:
- ampulla
recti (rectum in a narrower sense) - cranial part, length
10-12 cm, in the range of flexura sacralis, perineal flexure passes into:
- canalis analis – length 2.5-3.8 cm, narrower, differs in the longitudinal
orientation of the mucosal folds.
Vascular supply
Ø
a.
mesenterica inferior
Ø
a. rectalis superior
Ø
a. haemorrhoidales
Ø
v. mesenterica inferior➡️ v.portae
Ø
v. rectalis➡️ v.portae i VCI
Muscles of pelvic floor
Ø
levator ani
Ø
m. coccygeus
Ø
m. Piriformis
Ø
fascia perinea profunda
Ø
m. transversus perinei superf.
Ø
m. ischiocavernosus
Ø
m. sphincter ani externus
Frank H. Netter, Netterův anatomický atlas člověka. 2005
For more detailed information see anatomy and histology, physiology,
review the defecation reflex.