: Sacrum and Innominates
Comprehensive OMT reference hub, interactive cheat sheets, and board review notes for COMLEX Level 1, 2-CE, and 3.
Key Takeaway
Sacral torsions are diagnosed using the Seated Flexion Test (SFT), Spring Test, and Sphinx Test. Negative spring (good spring) = Forward Torsion (R-on-R, L-on-L). Positive spring (poor spring) = Backward Torsion (R-on-L, L-on-R). Innominate dysfunctions are identified via Standing Flexion Test (SFT) and landmark asymmetry.
1. Sacral Axes & Physiological Motion
The sacrum articulates with L5 superiorly and both ilia laterally at the sacroiliac (SI) joints. Sacral motion occurs around four primary axes.
| Sacral Axis | Anatomical Level | Associated Physiological Motion |
|---|---|---|
| Superior Transverse Axis | S2 level (posterior to SI joint) | Cranial & Respiratory motion. Inhalation = Sacral Extension (counternutation); Exhalation = Sacral Flexion (nutation). |
| Middle Transverse Axis | S2 level (sacral body) | Postural motion. Forward bending = Sacral Flexion; Backward bending = Sacral Extension. |
| Inferior Transverse Axis | S3 level (inferior SI joint) | Dynamic innominate motion on sacrum during gait. |
| Oblique Axes (Right & Left) | Superior pole of one SI joint to opposite inferior pole | Torsional motion during walking. Named for superior pole origin. |
2. Sacral Diagnostic Algorithm Matrix
Diagnosing sacral dysfunctions requires a step-by-step 3-part evaluation: Seated Flexion Test, Spring/Sphinx Test, and Landmark Palpation.
| Sacral Dysfunction | Seated Flexion Test | Spring / Sphinx Test | Deep Sulcus | Posterior/Inferior ILA |
|---|---|---|---|---|
| Left-on-Left ($L-on-L$) | Positive RIGHT | Negative Spring (Good) / Sphinx Improves | Left | Right |
| Right-on-Right ($R-on-R$) | Positive LEFT | Negative Spring (Good) / Sphinx Improves | Right | Left |
| Left-on-Right ($L-on-R$) | Positive LEFT | Positive Spring (Stiff) / Sphinx Worsens | Left | Right |
| Right-on-Left ($R-on-L$) | Positive RIGHT | Positive Spring (Stiff) / Sphinx Worsens | Right | Left |
| Bilateral Sacral Flexion | Bilateral Negative | Negative Spring / Sphinx Improves | Bilateral Deep | Bilateral Shallow |
| Bilateral Sacral Extension | Bilateral Negative | Positive Spring / Sphinx Worsens | Bilateral Shallow | Bilateral Prominent |
GOLDEN RULES OF SACRAL TORSIONS: - Forward Torsions ($L-on-L$, $R-on-R$): Spring test is NEGATIVE (good spring) and Sphinx test IMPROVES. L5 exhibits Type I neutral mechanics. - Backward Torsions ($L-on-R$, $R-on-L$): Spring test is POSITIVE (poor spring) and Sphinx test WORSENS. L5 exhibits Type II non-neutral mechanics. - Oblique Axis Side: The axis is ALWAYS on the side OPPOSITE to the positive Seated Flexion Test!
3. Innominate Somatic Dysfunctions
Innominate dysfunctions are identified by a positive Standing Flexion Test (SFT) on the affected side and specific pelvic landmark asymmetries (ASIS, PSIS, Ischial Tuberosity, Pubic Tubercle).
| Dysfunction (Positive SFT Side) | ASIS Finding | PSIS Finding | Leg Length & Ischial Tuberosity | MET Muscle Target |
|---|---|---|---|---|
| Anterior Innominate Rotation | Inferior / Anterior | Superior / Posterior | Longer leg; Ischial tuberosity inferior | Hamstrings |
| Posterior Innominate Rotation | Superior / Posterior | Inferior / Anterior | Shorter leg; Ischial tuberosity superior | Quadriceps & Rectus Femoris / Psoas |
| Superior Innominate Shear (Upslip) | Superior | Superior | Shorter leg; Pubic tubercle & Ischium superior | Leg Traction with respiratory cooperation |
| Inferior Innominate Shear (Downslip) | Inferior | Inferior | Longer leg; Pubic tubercle & Ischium inferior | Prone pelvic compression |
| Innominate Inflare | Medial (closer to midline) | Lateral | ASIS less prominent | Hip External Rotators |
| Innominate Outflare | Lateral (further from midline) | Medial | ASIS more prominent | Hip Adductors |
4. Pubic Symphysis Dysfunctions
- Superior Pubic Shear: Pubic tubercle superior on positive SFT side; tender inguinal ligament. Treat via Shotgun Technique (resisted isometric abduction followed by adduction).
- Inferior Pubic Shear: Pubic tubercle inferior on positive SFT side. Treat via Shotgun Technique or MET engaging gracilis.
5. COMLEX Practice Knowledge Check
Source
Based on the publicly available table of contents and topic organization of OMM Review: A Comprehensive Review of Osteopathic Medicine. All notes are original; no copyrighted text, figures, or full source material is included.