Interspinous ligaments !
The interspinous ligaments are thin sheets between neighbouring spinous processes, the bumps down the back; they limit forward bending.
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What it is
Thin sheets of ligament between neighbouring spinous processes (the bumps you feel down your back).
What it does
Limit forward bending and separation of the spinous processes.
Key facts
- Attaches
- Between adjacent spinous processes, root to tip; blend with ligamentum flavum in front and supraspinous ligament behind; thin in neck, strong in lumbar region
- Function
- Limit flexion and separation of spinous processes
- Tight in
- Flexion
Relations
- Course
- Midline needle path: after the skin, fat and supraspinous ligament, the needle crosses it before reaching the ligamentum flavum
- In front
- Ligamentum flavum and, beyond it, the posterior epidural space
- Behind
- Supraspinous ligament, then fat and skin
- Lateral
- Interspinales muscles and multifidus on each side
How to find it
Felt only indirectly: with the trunk bent forward, a fingertip pressed into the gap between two lumbar spinous processes lies over it, deep to the supraspinous ligament. This gap is the midline entry point for lumbar puncture.
On imaging
Sagittal fat-suppressed MRI (STIR) shows high signal from oedema or tearing after a flexion injury. The lateral radiograph shows widening between spinous processes; X-rays and CT show contact between them in kissing spines (Baastrup disease).
Common problems
- Strain or tears in flexion injuries; 'kissing spine' (Baastrup) when the processes rub in older adults.
How it is diagnosed
MRI for ligament injury; X-rays and CT for kissing spines.
Treatment
- Usually physical therapy and pain medicine; injections for Baastrup's disease.
Clinical notes
- In flexion-distraction (Chance-type) injuries it tears with the rest of the posterior ligamentous complex; MRI evidence of this guides decisions about stability
- When the ligaments are calcified or the spinous processes crowd together, a paramedian approach for lumbar puncture avoids the supraspinous and interspinous ligaments
- Interspinous spacers placed between spinous processes for neurogenic claudication sit in the space this ligament fills
Test yourself
Think of the answer, then tap the question to see it.
In a midline lumbar puncture, when does the needle cross the interspinous ligament?
Second: after the supraspinous ligament and before the ligamentum flavum; it feels firm.
Which structures form the posterior ligamentous complex that includes the interspinous ligaments?
The supraspinous and interspinous ligaments, the ligamentum flavum and the facet capsules; its disruption after trauma signals instability.
Which lateral X-ray sign suggests an interspinous ligament tear after a flexion injury?
Fanning: widening of the gap between two spinous processes.
What is Baastrup disease, in the region of the interspinous ligaments?
«Kissing spine»: adjacent spinous processes rub together in older adults; X-rays and CT show the contact.
Educational information, not medical advice. For any symptom, see a health professional.
Its names
- Official Latin (TA2)
- ligamenta interspinalia TA2 1674
- Official Spanish (DeCS)
- Ligamentos interespinosos
- English (TA2)
- Interspinous ligaments
Related
Sources: Terminologia Anatomica (TA2); Anatomy, Back, Lumbar Spine; Anatomy, Back, Posterior Longitudinal Ligament.
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Representative model, for educational purposes only.
