Why Do We Need The Intrinsic Muscles of the Foot? [Guide 2019]
The Intrinsic Foot Muscles
You may never have heard of the intrinsic muscles of the foot, but these little fellows are helping you to stay upright every time you stand, walk, or run.
The extrinsic muscles on the other hand are much better known, they include the calf muscles (soleus and gastrocnemius) and Tibialis Anterior, Tibialis Posterior, Extensor Digitorum Longus, Extensor Hallucis Longus, Flexor Hallucis Longus, Flexor Digitorum Longus, and the Peroneals (Longus, Brevis, and Tertius).
What are Intrinsics?
The intrinsic muscles of the foot are all the muscles that are contained within the foot itself, as opposed to extrinsic muscles which also control the foot, but are actually outside of it and are located on the lower leg bones, the tibia and fibula.
There are four layers of intrinsic muscles beneath the foot and one lone muscle on top of the foot, Extensor Digitorum Brevis.
Why Should You Care about the Intrinsic Foot Muscles?
We used to believe that the intrinsic muscles didn’t do a lot because of their small size.
We knew they were important for keeping the toes straight and and for flexing and extending the toes to facilitate ambulation (walking or running).
But improved research techniques over the past 10 years have given us much better insight into what the intrinsics are capable of.
Some researchers including Luke Kelly of The Gold Coast discovered ground breaking information by inserting fine wire EMGs into the muscles themselves and started putting them through load.
From this we learned out a number of things
- The intrinsic muscles are much stronger than we realised
- They contribute significantly to our ability to balance whilst on our feet. This is a really important finding that has changed the way we look at balance issues and falls risk.
- They help to prevent our medial longitudinal arch from collapsing (the main arch of the feet). Again this is huge news because we now know that the intrinsics work with the plantar fascia (aponeurosis) to absorb load and prevent the arch from collapsing (pronation).
- They don’t become more rigid when barefoot – in fact the exact opposite was found! They become slack to absorb shock, and become rigid when in a soft shoe to provide a rigid lever.
Who Can Benefit From Stronger Intrinsic Muscles?
Almost everyone! So if you are a/an:
- Elite athlete
- Casual runner or walker
- Weekend warrior
- Elderly person concerned about balance
- Young adult wanting to remain fit and strong
Can Intrinsic Muscles Help prevent Injury?
Important Note: Long term studies of patients with weak or strong intrinsic muscles have not yet been conducted.
But given what we now know about intrinsic foot muscles we can only assume that they will help to prevent injuries that are caused by or contributed to by the collapse of the medial arch of the foot.
There are an abundance of injuries that we believe are contributed to by a collapse of the arch, and therefore may be prevented by strengthening our intrinsic muscles thereby offloading the structure of the foot.
These may include:
- Plantar Fasciitis
- Shin Splints
- Some knee injuries
- Tibialis Posterior Tendinitis
- Trochanteric Bursitis and many more.
Okay, So How Do we Strengthen Our Intrinsics?
There are several exercises that have been found to be very useful in strengthening our intrinsic muscles thereby improving our balance during stance and gait and make us more resilient against injury risk.
Short Foot exercise
Splayed Toes Exercise
– To the right is a video on the splayed toes exercise. In this exercise you are trying to splay your toes effectively pulling the big toe and the pinkie toe away from the rest, again whilst keeping your heel and ball of the foot on the floor.
This is another quite simple exercise to strengthen your intrinsic foot muscles.
Simply place a towel on the floor and place your foot on the towel.
Now using only your toes, pick up the towel and drag it backwards under your foot. Repeat this until there is no more towel left to drag as it is all underneath your foot. Repeat 4 times on each foot.
The intrinsic muscles include:
- Abductor Hallucis
- Quadratus Plantae
- Flexor Hallucis Brevis
- Flexor Digitorum Brevis
- Adductor Hallucis
- Abductor Digiti Minimi
- Flexor Digiti Minimi
- The Interossei Muscles
- The Lumbricals
The Extrinsic Muscles of the Foot and Ankle are:
- Gastrocnemius medial and lateral heads
- Tibialis Posterior
- Extensor Digitorum Longus
- Extensor Hallucis Longus
- Flexor Digitorum Longus
- Flexor Hallucis Longus
- Peroneus Longus
- Peroneus Brevis
- Peroneus Tertius