📝 STANDARD DESCRIPTION:
Form roof of thorax; carry ribs.
Ox Standard:
- Number: 13 (T1-T13).
- Spinous processes are LONG, plate-like, directed caudally (form withers).
- Anticlinal vertebra = T13 (spine vertical; spines cranial to it slope back, caudal slope forward).
- Each has 2 demi-facets on body + 1 facet on transverse process for rib head & tubercle.
- Vertebral foramen is small.
📚 DETAILED DESCRIPTION:
THE ROOF BEAMS OF THE CHEST
Thoracic vertebrae are the bony pillars from which the ribs hang and form the dorsal wall (roof) of the thoracic cavity. In ox there are 13, equal to the number of rib pairs.
TYPICAL FEATURES:
• Body: Short, with a pair of costal demi-facets (half-facets) cranially and caudally on each side. The head of a rib articulates with two consecutive vertebrae across the intervertebral disc.
• Transverse process: Bears a costal facet (transverse costal fovea) for the tubercle of the rib.
• Spinous process: Long and tall in cranial thoracics (T2-T5 build up the WITHERS). Becomes shorter caudally.
• Anticlinal vertebra (T13 in ox): Its spine stands vertical. Spines in front of it slope backward; spines behind it slope forward. Acts as the 'pivot' of the back.
SPECIAL VERTEBRAE:
• T1: Largest body, short spine; carries 1st rib.
• Last thoracic (T13): Anticlinal; spine like a lumbar vertebra.
CLINICAL POINT: Long spines of T2-T5 form a palpable 'hump' between shoulders = WITHERS. Site for saddle/yoke pressure injuries (fistulous withers).
// COMPARATIVE ANALYSIS
| HORSE |
18 thoracic vertebrae. Anticlinal = T16. Withers very prominent. |
| DOG |
13. Anticlinal = T11. Spines shorter, more uniform. |
| PIG |
14-15 (variable). Spines flat and broad. |
| FOWL |
T1-T5 fused into NOTARIUM. Last thoracic fused with synsacrum. No flexible thoracic spine. |
CLINICAL RELEVANCE
Fistulous Withers (Cattle/Horse): Infection of the supraspinous bursa over T2-T5 spines from yoke/saddle pressure. Causes a draining wound on top of shoulders.
