📝 STANDARD DESCRIPTION:
High-Yield Points:
• Number: 6 lumbar vertebrae in ox (formula: C7 T13 L6 S5 Cy18-20).
• Form the roof of the abdominal cavity.
• Long, flat, horizontal transverse processes (mistakenly called 'lateral wings') — give origin to abdominal & sublumbar muscles; palpable per rectum.
• Long, prominent spinous processes — for epaxial muscle (longissimus) attachment.
• Articular processes deeply interlocking → strong but limited rotation.
• L1-L2 = site of paravertebral nerve block (anaesthesia of the flank).
📚 DETAILED DESCRIPTION:
LUMBAR VERTEBRAE — ROOF OF THE ABDOMEN
The lumbar region of the spine forms the dorsal wall (roof) of the abdominal cavity. The bovine vertebral formula is C7 T13 L6 S5 Cy18-20.
FEATURES of a typical bovine lumbar vertebra:
• Body: Long, slightly constricted in the middle, with flat ends.
• Spinous Process: Tall, flat, plate-like; directed nearly vertically; for attachment of the longissimus dorsi, multifidus.
• Transverse Processes: Very long, flat, plate-like (also called 'lateral wings'); directed cranio-laterally; the tips of L1-L5 give origin to abdominal muscles and to psoas/quadratus lumborum. The tip of L5 (or L6) is palpable per rectum as a useful landmark.
• Articular Processes: The cranial articular processes of one vertebra clasp the caudal processes of the one in front like 'fingers in a glove' → very strong, limits rotation, allows only flexion-extension.
• Vertebral Foramen: Narrow — contains the spinal cord and cauda equina; in adult cattle the spinal cord reaches approximately the first sacral vertebra (and extends farther caudally in young calves).
CLINICAL SITES:
• Para-Lumbar Fossa = depression in left flank bounded by the last rib (cranially), tips of lumbar transverse processes (dorsally), and cranial border of tuber coxae (caudally). It is the surgical window into the abdomen.
• Paravertebral nerve block (Farquharson's or Cambridge technique) anaesthetises T13, L1, L2 spinal nerves at their emergence under transverse processes — produces flank desensitization for rumenotomy/caesarean.
// COMPARATIVE ANALYSIS
| HORSE |
Only 6 lumbar vertebrae typically (five lumbar vertebrae may occur in some Arabians as a numerical variation; this should not be described simply as L5-L6 fusion with the sacrum). Transverse processes shorter, the L5-L6 articulate with each other and with sacrum (intertransverse joints) — gives a stiffer back. |
| DOG |
7 lumbar vertebrae. Transverse processes long, slender, project cranio-ventrally. Last rib common site of nephropexy approach. |
| PIG |
6-7 lumbar vertebrae. Transverse processes shorter than ox. |
| FOWL |
Lumbar vertebrae fused with last thoracics, sacrals, and first coccygeals into a single bone — SYNSACRUM. |
CLINICAL RELEVANCE
Paravertebral Nerve Block (T13, L1, L2): Local anaesthetic at the cranio-lateral aspect of transverse processes — desensitises the flank for standing rumenotomy or caesarean. Sub-lumbar Abscess: Common in cattle from foreign body migration — palpable per rectum at L4-L5 transverse processes. Vertebral Fracture / Subluxation: Result of mounting injuries — paraplegia.
