📝 STANDARD DESCRIPTION:
Pelvic Symphysis:
- Midline cartilaginous joint between right & left os coxae (pubis + ischium).
- Cartilaginous in young; gradually fuses with age.
- Loosens before parturition (relaxin).
Inguinal Canal (in male): Oblique passage in caudo-ventral abdominal wall.
- Internal (deep) inguinal ring: opening in transversalis fascia.
- External (superficial) inguinal ring: slit in external abdominal oblique aponeurosis.
- Transmits the SPERMATIC CORD.
Spermatic Cord contains:
1. Ductus (vas) deferens
2. Testicular artery, vein (pampiniform plexus), lymphatics
3. Nerves
4. Cremaster muscle
5. Tunica vaginalis
Prepubic Tendon: Strong tendinous insertion of rectus abdominis + adductor muscles + cremaster on the cranial pubic brim. Holds the abdominal wall onto the pelvis.
📚 DETAILED DESCRIPTION:
PELVIC SYMPHYSIS, INGUINAL CANAL & PREPUBIC TENDON
1. PELVIC SYMPHYSIS: The midline cartilaginous joint where the right and left pubis (cranially) and ischium (caudally) meet. In young animals it is cartilaginous (can flex). With age it gradually ossifies (turns to bone) and the two halves fuse. Just before parturition, hormones (relaxin) loosen the symphysis again — combined with sacroiliac relaxation, this widens the pelvic outlet for delivery.
2. INGUINAL CANAL: An oblique passage through the lower abdominal wall in the groin area. It connects the abdominal cavity to the scrotum (or the udder area in females). Two openings:
• Internal (deep) inguinal ring — internal opening, between the caudal border of internal abdominal oblique and the inguinal ligament.
• External (superficial) inguinal ring — external slit in the external abdominal oblique aponeurosis.
The canal in male transmits the SPERMATIC CORD (down to scrotum). In female it transmits only the round ligament of the uterus and the external pudendal vessels.
3. SPERMATIC CORD — CONTENTS:
From inside out, key structures of the spermatic cord are:
• Ductus (vas) deferens — sperm-carrying tube.
• Testicular artery — coiled (pampiniform).
• Pampiniform plexus of veins — surrounds the artery; cools incoming arterial blood (helps temperature regulation of testis).
• Lymphatics + autonomic nerves.
• Cremaster muscle (slip of internal abdominal oblique) — raises and lowers the testis with temperature changes.
• Tunica vaginalis (parietal & visceral layers) — outer covering, derived from peritoneum.
4. PREPUBIC TENDON:
A strong tendinous structure on the cranial pubic brim, formed by the combined insertion of the rectus abdominis, the abdominal tunic, and the pectineus / adductor and gracilis muscles. It anchors the abdominal floor to the pelvis. Importance:
• Holds the heavy gravid uterus + abdominal contents onto the pelvic frame in pregnant cows and mares.
• Rupture of the prepubic tendon (mare): Late-pregnancy disaster; mare's belly literally drops between the hind legs — life-threatening.
CLINICAL OPERATIONS in this region:
• Castration: Removal of testis through scrotal incision (open or closed method).
• Vasectomy: Cut/ligation of vas deferens within the spermatic cord — sterilizes but preserves libido (used for teaser bulls).
• Inguinal Hernia: Abdominal contents (intestine) escape through the inguinal canal into the scrotum.
// COMPARATIVE ANALYSIS
| STALLION |
Wide inguinal canal — INGUINAL HERNIA more common. |
| MARE |
Prepubic tendon RUPTURE risk near foaling, especially with twins. |
| BULL |
Symphysis ossifies early — rigid pelvis (hence dystocia common in heifers). |
CLINICAL RELEVANCE
Castration: Scrotal incision → spermatic cord identified → emasculator crushes & cuts cord above testis. Bloodless (Burdizzo) method crushes cord externally without cutting skin.
Vasectomy: Small skin incision over cord → ductus deferens isolated and a section removed → animal sterile but retains testosterone (used for 'teaser' bulls).
Inguinal Hernia (stallion, boar): Loop of intestine slips through internal inguinal ring → emergency surgery if strangulated.
Prepubic Tendon Rupture: Pregnant mare's belly drops dramatically; medical emergency.
