Axial skeleton descriptors
| Descriptor | Definition |
| Head and neck position during high impact: identifies the alignment of the head and neck during any impact that has been identified as HIGH (see table 4) or has occurred to the head. Where multiple high impacts have been sustained, code head and neck alignment for each high impact sustained. Combined movement (code each discrete movement observed) | Neutral |
| Flexion | |
| Extension | |
| Lateral flexion—right | |
| Lateral flexion—left | |
| Rotation—right | |
| Rotation—left | |
| Torso position during high impact: identifies the alignment of the torso during any impact that has been identified as HIGH (see table 4) or has occurred to the head. Where multiple high impacts have been sustained, code torso alignment for each high impact sustained. Combined movement (code each discrete movement observed) | Neutral |
| Flexion | |
| Extension | |
| Lateral flexion—right | |
| Lateral flexion—left | |
| Rotation—right | |
| Rotation—left | |
| Axial skeleton orientation upon commencement of fall/unseat: the orientation of the head in relation to the pelvis upon commencement of fall/unseat. Please note: the commencement of a fall as previously defined is the point at which the jockey parts company from his/her horse from which they cannot recover. Reference points/landmarks: 1. head—apex of helmet; 2. pelvis—top of the breeches (as this can be easily distinguished from the bottom of the silks) | Head above the height of the pelvis |
| Head level with pelvis | |
| Head below the height of the pelvis | |
| Axial skeleton orientation upon impact: the orientation of the head in relation to the pelvis during initial impact. Reference points/landmarks: 1. head—apex of helmet; 2. pelvis—top of the breeches (as this can be easily distinguished from the bottom of the silks) | Head above the height of the pelvis |
| Head level with pelvis | |
| Head below the height of the pelvis | |
| Angle of impact: observed angle between the longitudinal axis of the identified body part and the impact surface upon impact | Vertical |
| Angled | |
| Head impact sustained: identifies if jockey sustained an impact to the head during inciting event | Head impact sustained |
| No head impact sustained | |
| Not visible | |
| Head impact location: identifies the anatomical region of the head where the impact is sustained, for example, forehead=anterior | Anterior |
| Posterior | |
| Lateral—right | |
| Lateral—left | |
| Anterolateral—right | |
| Anterolateral—left | |
| Posterolateral—right | |
| Posterolateral—left | |
| Head impact intensity: subjective description of the impact sustained by the jockey’s head | Low |
| Moderate | |
| High | |
| Head impact surface: the surface which the jockey’s head impacts | Ground |
| Obstacle—fence/railing | |
| Stalls | |
| Horse/rider | |
| Head movement direction: identifies biomechanical plane(s) of the jockey’s head motion upon impact | Sagittal: forward–backward movements36 |
| Coronal: side-to-side movements36 | |
| Transverse: rotational or twisting movements36 | |
| Multiplane: movements incorporating more than one plane36 | |
| Not visible/inconclusive: unable to definitively identify plane36 | |
| Head rebound: identifies whether the jockey’s head rebounds immediately after impact | Yes: head rebound visible |
| No: no head rebound visible | |
| Not visible/inconclusive: unable to definitively identify any head rebound | |
| Head acceleration: identifies biomechanical plane(s) of jockey’s head motion (where acceleration observed, and no impact sustained) | Sagittal: forward–backward movements36 |
| Coronal: side-to-side movements36 | |
| Transverse: rotational or twisting movements36 | |
| Multiplane: movements incorporating more than one plane36 | |
| Not visible/inconclusive: unable to definitively identify plane36 | |
| Observed signs of possible concussion35 | Lying motionless: lying without purposeful movement on the racetrack, for >2 s*. Does not appear to move or react purposefully, respond or reply appropriately to the race situation.35 |
| Motor incoordination: appears unsteady on feet (including losing balance, staggering/stumbling, struggling to get up, falling) or in the upper limbs (including fumbling). May occur in rising from the racetrack surface or in the motion of walking/running/skating35 | |
| Impact seizure: involuntary clonic movements that comprise periods of asymmetric and irregular rhythmic jerking of axial or limb muscles35 | |
| Tonic posturing: involuntary sustained contraction of one or more limbs (typically upper limbs), so that the limb is held stiff despite the influence of gravity or the position of the jockey. The tonic posturing could involve other muscles, such as the cervical, axial and lower limb muscles. Tonic posturing may be observed while the jockey is on the racetrack surface or in the motion of falling, where the jockey may also demonstrate no protective action* (*this was previously known as no protective action—stiff)35 | |
| No protective action—floppy: falls to the playing surface in an unprotected manner (ie, without stretching out hands or arms to lessen or minimise the fall) after direct or indirect contact with the head. The jockey demonstrates a loss of motor tone (which may be observed in the limbs and/or neck) before landing on the racetrack surface35 | |
| Blank/vacant look: the jockey exhibits no facial expression or apparent emotion in response to the environment* (*may include a lack of focus/attention of vision; blank/vacant look is best appreciated in reference to the jockey’s normal or expected facial expression)35 |
*>2s for removal and assessment of the jockey. Significantly longer periods of lying motionless may necessitate immediate and permanent removal from play, depending on the circumstances