The Rectum

Question 1

What are the cranial and caudal borders of the rectum?

Answer 1

Cranial -> pelvic inlet Caudal -> Anal canal

Question 2

What type of epithelium is on the rectal mucosa?

Answer 2

Columnar epithelium

Question 3

The rectum has the same layers as LI (mucosa, submucosa, muscularis and serosa). What are the two muscularis layers of the rectum?

Answer 3

Outer layer = Stratum longitudinal (runs dorosocaudally)-> forms rectococcygeus (poo mechanism) -> runs from rectum to tail.
Inner layer = Stratum circularis (caudally organised fibres -> forms anal sphincter m.)

Question 4

What structure provides the meseneteric support to the rectum?

Answer 4

Mesorectum (extension of mesocolon)

Question 5

Describe the vascular supply of the rectum

Answer 5

Cranial section = Cranial rectal artery (branch of caudal mesenteric)
Middle rectal and caudal rectal supplied by Branches of the Internal Pudendal artery

Question 6

Describe the venous drainage of the recumt

Answer 6

Cranial section = portal veins

Middle/Caudal = internal iliac vein

Question 7

Describe what local excision surgery is

Answer 7

Used to extract rectal masses close to the anus -> evert through the anus

Question 8

Describe what pull out excision surgery is

Answer 8

used to larger masses close to the anus with gentle eversion of the anus

Question 9

Describe the dorsal approach surgery

Answer 9

semicircular incisions from dorsal between anus and base of the tail

Question 10

Describe the ventral approach

Answer 10

Pelvic split needed -> sacroiliac subluxation (can do lateral approach also)

Question 11

What muscles make up the pelvic diaphragm? What is their combined function?

Answer 11

Coccygeus m., levator ani muscle and external anal sphincter m.
These provide the muscles for defaecation -> must compress pelvic contents

Question 12

Levator ani muscle function

Answer 12

Runs from pelvis and inserts onto the tail

Presses the tail against the anorectal region which compresses faecal material in an aboral direction

Question 13

Coccygeus muscle function

Answer 13

Runs from coccygeal vertebrae to the pelvis

Again compresses rectum during defaecation -> presses tail ventrally and causes lateral compression on the rectal wall

Question 14

External anal sphincter muscle

Answer 14

Skeletal muscle -> controls when the animal takes a shit

Question 15

What does the rectococcygeus do?

Answer 15

Stabilises rectum and anal canal during defaecation. Prevents rectum being pushed out
Sacrotuberous ligament