IVRI Anatomy
A free veterinary anatomy learning platform for B.V.Sc., M.V.Sc., DVM and veterinary medicine students worldwide, developed at the Veterinary Anatomy Section, ICAR-Indian Veterinary Research Institute, Bareilly—covering VCI/MSVE and international university curricula through regional anatomy, histology, embryology, comparative biomechanics, clinical notes, quizzes and revision.
The udder of the cow is a single mass formed by 4 fused mammae, each anatomically and functionally independent: milk produced in one quarter cannot pass to another. The 4 quarters are arranged as 2 fore-quarters and 2 hind-quarters; the hind quarters are typically larger and produce ~60% of the milk.
Internal Architecture of one quarter: Alveoli → small ducts → lactiferous (gland) sinus → teat sinus → streak canal (papillary duct) → exterior. A smooth-muscle teat sphincter surrounds the streak canal. Fürstenberg's rosette is the mucosal fold complex at the proximal end of the teat canal, not the sphincter itself.
Suspensory Apparatus:
• Median suspensory ligament (paired): elastic (yellow elastic tissue), in the midline — allows the udder to expand and recoil with milk volume.
• Lateral suspensory ligaments: fibrous (collagen), from sub-pelvic tendon — provide rigid lateral support.
Failure of these ligaments → broken/pendulous udder in old cows.
Vasculature: The principal artery is the external pudendal artery, which reaches the udder through the inguinal canal. Venous drainage includes external pudendal and subcutaneous abdominal pathways. The prominent subcutaneous abdominal 'milk vein' should not be taught as a routine IV-access site; the jugular vein is the standard large-animal venous-access site.
Lymphatics: Drain to the supramammary (mammary) lymph nodes located dorsocaudal to the gland — these are routinely palpated in cases of mastitis.
| COW | 4 quarters, 4 teats, 1 streak canal each. Functionally independent. |
| MARE | Single mammary gland mass with 2 teats; each teat has 2 streak canals (drains 2 lobes). |
| BITCH | Usually 5 pairs of mammae (2 thoracic, 2 abdominal, 1 inguinal); each teat has 7-16 ducts/streak canals. Common site of mammary tumours. |
| SOW | Multiple pairs (6-8 pairs) along the milk-line from thorax to inguinal region; each teat has 2 streak canals. |
Explore the hidden mechanics of why structures are present, absent or modified across domestic and wildlife species—and how each anatomical design supports movement, function and clinical practice.
Explanation goes here.