Which statement best describes a lateral anatomic variance that allows greater motion in the equine pelvis?

Which statement best describes a lateral anatomic variance that allows greater motion in the equine pelvis?

• A. Shorter last lumbar
• B. SP of lumbar angle cranially, SP of coccyx angle caudally
• C. No supraspinous ligament L5–L6
• D. All of the above

Answer: (D)

The question asks about anatomical features that can increase lateral motion of the horse’s pelvis. The pelvis moves more when dorsal and spinal restraints are reduced and the vertebral segments align in a way that allows more side-to-side shifting. A shorter last lumbar vertebra can lessen stiffness at the lumbosacral junction, making lateral tilting of the pelvis easier. If the spinous process of the lumbar segment is oriented cranially and the coccygeal spinous process is oriented caudally, this arrangement can alter the dorsal alignment and muscle/ligament attachments in a way that permits more lateral deviation. Additionally, removing the supraspinous ligament between L5 and L6 eliminates dorsal restraint at that level, increasing available motion. When these variations occur together, they collectively contribute to greater lateral mobility of the pelvis, making all of these features consistent with increased pelvic motion.

The question asks about anatomical features that can increase lateral motion of the horse’s pelvis. The pelvis moves more when dorsal and spinal restraints are reduced and the vertebral segments align in a way that allows more side-to-side shifting. A shorter last lumbar vertebra can lessen stiffness at the lumbosacral junction, making lateral tilting of the pelvis easier. If the spinous process of the lumbar segment is oriented cranially and the coccygeal spinous process is oriented caudally, this arrangement can alter the dorsal alignment and muscle/ligament attachments in a way that permits more lateral deviation. Additionally, removing the supraspinous ligament between L5 and L6 eliminates dorsal restraint at that level, increasing available motion. When these variations occur together, they collectively contribute to greater lateral mobility of the pelvis, making all of these features consistent with increased pelvic motion.