Ligaments
Mesenteries and omenta are folds of peritoneum. In addition, narrow strips of peritoneum are referred to as ligaments. They differ from ligaments associated with the skeleton in that they do not have attachments to bone.
Examples are the gastrosplenic, hepatoduodenal, falciform, inguinal and ovarian ligaments. The attachments of these ligaments are usually indicated by their names.3.4.1 Abdominal ligaments
The falciform ligament attaches to the parietal surface of the liver between the right and left medial lobes. Caudally it attaches to the body wall just cranial to the umbilicus. In young puppies a remnant of the umbilical vein, the teres ligament, is seen on the dorsal border of the falciform ligament. In the dog the falciform ligament becomes packed with fat and is often removed surgically to allow better access to the cranial abdomen.
The round ligament of the liver is a remnant of the umbilical vein of the foetus. It is only present in the young animal when it is there as a fibrous cord lying along the free edge of the falciform ligament.
The coronary ligament is present only as a peritoneal reflection between the liver and the caudal vena cava where it passes through the diaphragm.
The hepatorenal ligament extends from the caudate process of the liver to the ventral surface of the right kidney.
3.4.2 Pelvic ligaments
The urachus is a vestigial scar on the apex of the wall of the urinary bladder; it is the remains of the allantoic stalk that drains the nitrogenous waste from the embryonic urinary bladder to the placenta for excretion. The peritoneal fold that encloses the urachus becomes the middle ligament of the bladder. There are also, to either side, peritoneal folds that supported the umbilical arteries of the embryo; these become the lateral ligaments of the bladder. The umbilical arteries themselves become the round ligaments of the urinary bladder.
Blind-ending peritoneal pouches lie between the pelvic viscera and are directed cau- dally. They are named according to their attachments, which are also their boundaries. The pubovesical pouch (not usually present in the female) lies between the pelvis and the urinary bladder; the rectogenital pouch lies between the rectum and the reproductive tract; and the vesicogenital pouch lies between the bladder and the reproductive tract.
The gubernacula are paired embryonic ligaments derived from mesenchyme and also called the caudal genital ligaments. They are present in both the male and the female but have more functional significance in the male. In the female they become the ovarian and the round ligaments.
3.4.3 Pelvic ligaments - female
A number of ligaments are attached to the pelvic viscera. In the female these structures attach the female reproductive tract to the body wall. They are:
1) Broad ligaments: These are paired sheet-like double folds of peritoneum. They are attached dorsally to the body wall at the level of the psoas and transversus abdominis muscles. They contain and suspend the ovaries, oviducts and uterine horns together with the associated blood vessels and nerves. The sections of the broad ligaments that attach to the female reproductive tract are the mesovarium (ovary), the mesosalpinx (uterine tube, Fallopian tube, oviduct), the mesometrium (uterus) and the mesovagina (vagina).
2) Round ligament of the uterus: This is a thickened cord of a separate fold of the broad ligament. It is the female homologue of part of the gubernaculum (see Section 16.9). In the bitch the round ligament passes through the inguinal canal to insert near the vulva, thereby providing the potential for inguinal hernia.
3) Proper ligament of the ovary: The rest of the gubernaculum, extending from the ovary to the paramesonephric duct, becomes the proper ligament of the ovary. The ovaries are secured by proper and suspensory ligaments. The proper ligament attaches the ovary to the cranial extremity of the corresponding uterine horn.
4) The suspensory ligament attaches the ovary to the medial surface of the last rib.
3.4.4 Pelvic ligaments - male
In the male the gubernaculum extends from the caudal pole of the testis, through the inguinal canal, to the distal scrotum. The proper ligament of the testis attaches the testis to the parietal layer of the peritoneum via the tail of the epididymis (Figure 16.4). See Sections 16.8 and 16.9 for details of the function of the gubernaculum in the descent of the testes.
The gubernacula are paired embryonic ligaments derived from mesenchyme and also called the caudal genital ligaments. They are present in both the male and the female but have more functional significance in the male. In the female they become the ovarian and the round ligaments.
In the immature male the paired gubernacula extend through the inguinal canals to attach to the testes. The proper ligament of the testis attaches the testis to the parietal layer of the peritoneum via the tail of the epididymis (Figure 16.4). The function of the gubernaculum in the descent of the testis is discussed in Section 16.9.