Spine

The spine is a body part common to all vertebrates, and may be used as an optional hit location. It is best used in high-realism adventures, or those with lots of martial arts. Not to be confused with spines, the advantage of having spiky protrusions.

Getting Hit In The Spine

A successful attack to the spine causes immediate knockdown and stunning, even if the damage is only 1. With a major wound to the spine, the knockdown roll is at -5! Severe wounds (one's whole HP) causes automatic knockdown and stunning, and immediately cause Bad Back and Paraplegic. Luckily all ordinary melee/ranged attacks to the spine are at a whopping -8, and the spine gets DR 3.

Wrench Spine and Backbreaker are two techniques that attack the spine directly.

Overpenetration

Only allowing attacks from behind to target the spine seems problematic, because it should be possible for attacks from the front to overpenetrate whatever is blocking the spine to then hit the spine, involving some kind of Cover DR.

Overpenetration rules basically give cover equal to HP (it only takes more than HP/2 to inflict a Major Wound by comparison) so it might make sense to allow someone to target the spine from the front but only actually hit it if inflicting more than basic damage exceeds HP.

Forums

Kromm in 2013 http://forums.sjgames.com/showthread.php?t=111628 wrote about targeting the CERVICAL (neck) spine in particular:

By a strict reading, if the spine in the torso (0) gives -8, then spine in the neck (-5) should give -13. I find this rather excessive, though. I would simply observe that the usual ratio of cervical vertebrae to the remainder of the spine is about 1:4, and note that 1/4 has the effect of adding between -3 and -4 to hit on p. B550. I'd go with -3 and call this -11 to hit.

With this end result:

Cervical Vertebrae (-11): Crushing, cutting, impaling, piercing, and tight-beam burning attacks from behind can target the spine in the neck. The vertebrae provide an additional DR 3. Use the wounding modifiers for the neck, but any hit for enough injury to inflict a shock penalty requires a knockdown roll, at -5 if a major wound. Injury in excess of HP cripples the spine. This causes automatic knockdown and stunning, plus all the effects of Quadriplegic (p. B150). Roll after the fight to avoid gaining this disadvantage on a lasting or permanent basis! A miss by 1 hits the neck.

Anatomical Notes

Cervical vertebrae usually have 7 bones (exceptions: manatee and sometimes 2-toed sloth have 6, three-toed sloth has 9) so a 1:4 ratio suggested by Kromm would suggest there are 28 bones in the rest of the spine.

• The human thoracic spine has 12 while the human lumbar spine has 5, totalling only 17. 17 is closer to 14 (a 1:2 ratio) than 21 (a 1:3 ratio) much less 28, so when Kromm refers to a 1:4 ratio he must be referencing the actual height of the spine (because the lumbar/thoracic vertebrae are THICKER) rather than actually the number of vertebrae.