The deep lying posterior tibialis is the most central of all leg muscles and is the key stabilizing muscle of the lower leg. So you would think it would have a much higher profile in all our movement classes. That is all about to change: it’s posterior tibialis’ time to shine!
Way back in my younger years as a dancer I complained to my ballet teacher that my Achilles tendon was irritated and my calves looked too big. She watched me point and go up on demi-point (heel raises) and immediately commented that I was overly focused on lifting my heel. The problem, she said, was that I need to access and awaken my posterior tibialis (PT). What? I had never heard of this muscle, but had heard of the anterior tibialis (think shin splints). To plantar flex my foot, she explained, I needed to focus on pressing my arch away rather than lifting my heel, and instead of hiking my heels up, focus on pressing the ball of my foot down into the floor. Wow, what a difference! I accessed a deeper muscle to support my larger superficial muscles – and that muscle was the PT. My calf slimmed down and my inflamed Achilles tendon healed.
The PT originates behind the tibia and fibula (lower leg bones), and the interosseous membrane (the fascia connecting tibia and fibula). It runs in the deep posterior compartment (in the middle of your lower leg) and travels behind the medial malleolus (inside ankle bone). It inserts into the navicular bone and connects via fascia to the calcaneus (heel bone), all 3 cuneforms, cuboid and 2nd, 3rd, and 4th metatarsals. In other words, a lot of the bones in your foot!
Its main job is to help create the medial arch and to invert and plantar flex the foot at the ankle, helped by flexor hallucis longus and flexor digitorurm longus.
Without a healthy functioning PT your medial arch will fall (flat foot), and the heel bone will have a valgus deformity which will affect the whole chain up your leg and into your pelvis. Knee caps will look inward at each other creating knock knees – the list goes on and on.