: Cervical Spine
Comprehensive OMT reference hub, interactive cheat sheets, and board review notes for COMLEX Level 1, 2-CE, and 3.
Key Takeaway
The cervical spine comprises three distinct functional units: the OA joint (flexion/extension dominant with opposite SB/rotation), the AA joint (rotation dominant, tested in 45° neck flexion), and typical cervicals C2–C7 (coupled SB and rotation to the same side). Always test vertebral artery patency (DeKleyn test) and respect absolute contraindications (RA, Down syndrome) prior to cervical HVLA.
1. Cervical Anatomy & Structural Landmarks
The cervical spine consists of seven vertebrae (C1–C7) divided into two major anatomical divisions: the craniovertebral junction (Occipitoatlantal OA joint and Atlantoaxial AA joint) and the inferior typical cervical spine (C2–C7). Understanding bony landmarks and neurovascular pathways is essential for safe diagnosis and treatment.
| Segment | Anatomical Landmark / Feature | Clinical & COMLEX Significance |
|---|---|---|
| C1 (Atlas) | Ring-shaped vertebra lacking a vertebral body or spinous process. | Articulates with occipital condyles; houses transverse ligament of atlas. |
| C2 (Axis) | Odontoid process (dens) projecting superiorly; first palpable spinous process. | Pivot axis for AA rotation; site of dens fracture in hyperextension trauma. |
| C3–C6 | Bifid spinous processes; transverse foramina for vertebral artery. | Typical cervicals; anterior tubercle of C6 is Chassaignac's carotid tubercle. |
| C7 (Vertebra Prominens) | Large, non-bifid spinous process; vertebral artery enters at C6, NOT C7! | Major superficial palpation landmark for root of neck; transitional segment. |
High-Yield Vascular Anatomy Trap: The vertebral artery ascends through the transverse foramina of C6 through C1 before entering the foramen magnum. It does NOT pass through the transverse foramen of C7! Extension and rotation of the cervical spine compress the contralateral vertebral artery in the suboccipital region.
2. Joint-by-Joint Biomechanics & Diagnostic Protocols
Each cervical region obeys distinct biomechanical rules during motion testing. COMLEX questions frequently test the mechanical differences between OA, AA, and typical C2–C7 segments.
A. Occipitoatlantal (OA) Joint: C0–C1
- Primary Motion: Flexion and Extension ('Yes' joint), accounting for 50% of total cervical flexion/extension.
- Coupling Rules: Exhibits Pseudo-Type I behavior. Sidebending and Rotation ALWAYS OCCUR IN OPPOSITE DIRECTIONS regardless of whether the joint is neutral, flexed, or extended (e.g., $OA\ F\ S_L R_R$).
- Translation Testing: Translating the head to the Right induces Left Sidebending, which automatically couples with Right Rotation.
B. Atlantoaxial (AA) Joint: C1–C2
- Primary Motion: Rotation ('No' joint), accounting for 50% of total cervical rotation (45° in each direction).
- Diagnostic Setup: Tested in FULL NECK FLEXION (approx. 45° flexion). Flexing the cervical spine engages the facet locks of C2–C7, isolating motion strictly to the AA joint.
- Dysfunction Naming: Named solely for the restricted direction of rotation (e.g., $AA\ R_L$ or $AA\ R_R$).
C. Typical Cervical Spine: C2–C7
- Facet Orientation: BUM (Back, Up, Medial) in the coronal/sagittal plane angled at 45°.
- Coupling Rules: Exhibits Fryette-like Type II behavior. Sidebending and Rotation ALWAYS OCCUR TO THE SAME SIDE whether in neutral, flexion, or extension (e.g., $C4\ F S_R R_R$).
- Translation Testing: Translating C3 to the Left pushes the articular pillar right $\rightarrow$ induces Right Sidebending $\rightarrow$ couples with Right Rotation.
3. Special Diagnostic Tests & Clinical Pathology Matrix
| Special Test | Execution & Mechanism | Positive Finding & Clinical Diagnosis |
|---|---|---|
| Spurling Test (Neck Compression) | Patient extends neck, sidebends toward affected side; physician applies axial downward compression. | Reproduction of radicular arm pain/paresthesias $\rightarrow$ Cervical Radiculopathy (nerve root compression). |
| Cervical Distraction Test | Physician applies upward traction under occiput and chin while patient is seated. | Relief of neck/arm pain $\rightarrow$ Confirms cervical radiculopathy or facet joint impingement. |
| DeKleyn Test (Wallenberg Test) | Patient supine, head extended, rotated, and sidebent to one side held for 30s. | Dizziness, vertigo, nystagmus, or slurred speech $\rightarrow$ Vertebral Artery Insufficiency. Absolute contraindication to HVLA! |
| Lhermitte Sign | Passive rapid neck flexion while patient is seated or supine. | Electric shock-like sensation radiating down spine into legs $\rightarrow$ Cervical cord compression, MS, or myelopathy. |
4. High-Yield OMT Setups, Tenderpoints, & Safety Contraindications
High-Yield Cervical Counterstrain Tenderpoints: - AC1 (Posterior margin of ascending ramus of mandible): Treat with $F\ S_A R_A$ (Flexion, Sidebend Away, Rotate Away). - AC7 (Clavicular insertion of SCM): Treat with $F\ S_A R_O$ (Flexion, Sidebend Away, Rotate Toward). - PC1 (Suboccipital): Treat with $E\ S_A R_A$ (Extension, Sidebend Away, Rotate Away). - PC3 (Lower spinous processes): Treat with $E\ S_A R_A$.
ABSOLUTE CONTRAINDICATIONS to Cervical HVLA: 1. Rheumatoid Arthritis (RA): Weakness/laxity of the transverse ligament of atlas $\rightarrow$ risk of atlantoaxial subluxation and fatal spinal cord transection. 2. Down Syndrome: Congenital hypoplasia of dens / laxity of transverse ligament. 3. Vertebral Artery Insufficiency / Dissection: Risk of brainstem stroke (Wallenberg syndrome). 4. Ankylosing Spondylitis / Cervical Spine Fusion: High risk of vertebral fracture.
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.