Overview
This lecture covers the anatomy, function, and clinical significance of the tibialis posterior muscle, including causes and treatments for related dysfunctions.
Tibialis Posterior Anatomy
- Originates from the posterior surface of the proximal tibia, proximal fibula, and interosseous membrane.
- Runs down the posterior tibia, passes medially through the tarsal tunnel behind the medial malleolus.
- Main insertion is the navicular tuberosity; also attaches to the cuneiform bones and bases of metatarsals 2, 3, and 4.
- Innervated by the tibial nerve (roots L4 and L5).
Functions and Roles
- Responsible for plantarflexion (pointing the foot down) and inversion (turning the sole inward) of the ankle.
- Primary inverter in plantarflexion; tibialis anterior is main inverter during dorsiflexion.
- Acts as a dynamic stabilizer of the medial longitudinal arch of the foot during weightbearing activities like walking.
Clinical Implications
- Overuse can lead to tibialis posterior tendinopathy, common with increased walking or running.
- Dysfunction results in loss of medial arch support, leading to flatfoot (pes planus) and potentially pes planovalgus, impacting foot and ankle joint health.
- Advanced dysfunction may cause osteoarthritis in the subtalar and ankle joints.
Assessment and Rehabilitation Strategies
- Early rehab: Non-weightbearing isometric or concentric exercises with theraband, focusing on plantarflexion and inversion.
- Progress to weightbearing exercises that focus on lifting and maintaining the medial longitudinal arch.
- Functional exercises include arch holds while rocking, heel raises, and exercises on declines to strengthen the muscle in its critical role.
Key Terms & Definitions
- Tibialis Posterior — Muscle on the back of the lower leg essential for foot inversion and arch support.
- Tarsal Tunnel — Passageway on the medial side of the ankle containing tendons, nerves, and blood vessels.
- Navicular Tuberosity — Main insertion point on the navicular bone for the tibialis posterior tendon.
- Pes Planus — Flatfoot condition due to collapsed medial arch.
- Pes Planovalgus — Flatfoot combined with outward angling (valgus) of the heel.
- Isometric Exercise — Muscle contraction without joint movement.
- Theraband — Elastic band used for resistance exercises.
Action Items / Next Steps
- Practice early and advanced exercises for tibialis posterior strengthening.
- Assess patients in weightbearing positions for accurate diagnosis and rehab.
- Review additional resources or webinars on tibialis posterior anatomy and treatment if needed.