topography of pelvic cavity

Boundaries of the pelvic cavity

Cranially: pelvic inlet (terminal line); dorsally: sacrum and first caudal vertebrae; laterally: ilium and sacrosciatic/sacrotuberous ligament; ventrally: pubis and ischium; caudally: pelvic outlet (ischiatic arch, sacrosciatic ligament, first caudal vertebrae)

Pelvic bones

Ilium, ischium, pubis, sacrum, and coccygeal (caudal) vertebrae

Sacrotuberous ligament

A ligament running from the sacrum to the ischiatic tuberosity; absent in the cat

Sacrosciatic ligament

A broad ligament found only in large animals (horses, ruminants), spanning from the sacrum/caudal vertebrae to the ischiatic tuberosity, helping to form the lateral wall of the pelvic cavity

3 ligaments leaving the sacrum

Dorsal sacroiliac ligament, sacrotuberous ligament (small animals) or sacrosciatic ligament (large animals), and ventral sacroiliac ligament

Muscles of the pelvis

Gluteal muscles

Pelvic diameter measurements

Conjugate diameter (oblique direction, from promontory to cranial pubic symphysis) and vertical diameter

Terminal line

The pelvic inlet boundary; its shape and the position of the ischial spines vary by sex and species (mare, stallion, cow)

Perineum regions

Anal region and urogenital region

Pelvic diaphragm muscles

Coccygeus and levator ani

Topographical arrangement of systems in the pelvic cavity (dorsal to ventral)

Dorsal: digestive system (rectum); Middle: reproductive system (uterus/vagina in females, ductus deferens and accessory glands in males); Ventral: urinary system (bladder, urethra)

Rectogenital pouch

Peritoneal pouch located between the rectum (dorsal) and the reproductive tract (ventral) - genital fold in males, uterus/vagina in females

Pubovesical pouch

Peritoneal pouch located between the pelvic symphysis (pubis) and the bladder

Vesicogenital pouch

Peritoneal pouch located between the bladder and the reproductive tract (uterus/vagina) in females

Male accessory sex glands present in all domestic species

Prostate gland and ampulla of the deferent duct

Male accessory sex glands unique to horses and ruminants (not present or much reduced in dog/cat)

Vesicular gland (seminal vesicle) and bulbourethral gland

3 glands present around the pelvic urethra in the horse

Vesicular gland, prostate gland, and bulbourethral gland (plus the ampulla of the deferent duct)

Prostate gland shape difference in the dog

Body of the prostate is described as "simple" (encircles the urethra as a single rounded body)

Bulbourethral gland location difference in the cat

Positioned most caudally along the pelvic urethra; different in the cat compared to the dog (dog lacks a prominent bulbourethral gland)

Difference in accessory gland size between stallion and bull

Bulbourethral gland much larger in the stallion; vesicular gland much larger (sizeable) in the bull

Where do the uterine horns differ most notably between species?

The curvature/orientation of the uterine horns changes between species - e.g., in the cow the horns curve upward/ventrally and you must reach ventrally to find the ovaries

Position of the ovaries in the mare compared to other species

Ovaries are much more dorsal in the horse (equine) than in the cow or dog

Structure connecting the kidneys to the urinary bladder

Ureters

Trigone of the bladder

Triangular area on the internal bladder wall bounded by the two ureteral orifices and (in males) the orifices of the deferent ducts at the colliculus seminalis; the ureteral orifices are the most cranial landmarks of the trigone in females

How does the ureter enter the bladder wall?

In an oblique direction, passing through the bladder neck/wall so that the opening can open and close (a valve-like mechanism preventing reflux)

Major artery supplying the pelvic organs

Internal iliac artery

Median sacral artery

Projects dorsally and continues as the coccygeal artery

Hypogastric nerve

Part of the pelvic autonomic supply; associated with the "recta plexus" (rectal/hypogastric plexus)

Pudendal nerve

Somatic nerve supplying the pelvic/perineal region

Lymph nodes of the pelvic region

Iliofemoral LN (related to external iliac artery), iliac LN - medial and lateral (related to internal iliac artery), and sacral LN (related to median sacral artery)

Rectal palpation - main uses

Female reproductive examination, clinical examination of the digestive system, prostate evaluation in small animals (males), and pelvic bone evaluation

Rectal palpation technique by species

Small animal: gloved finger; Large animal: full arm (sleeve/glove) inserted rectally

In the cow, how do you locate the ovaries during rectal palpation?

Follow the uterine horns, which curve upward, then reach ventrally to find the ovaries

Fixed abdominal/pelvic landmark organs used to orient during rectal palpation (large animal)

Left and right kidneys, spleen, stomach/rumen, liver, and pancreas, arranged in a ring around L1