Feet Flashcards
Purpose of Ankles and Feet
- The ankle allows the foot to take up any position in space.
- It helps the foot adapt to any irregularities of ground.
The entire body is affected by the mechanics of the foot, through its influence on the ankle, hip, knee, pelvis and vertebral column
Foot loading during Gait
Walking - 1.2x BW
Running - 2x BW
Jumping (height of 2 feet) - 5x BW
Roll and slide
- Ankle has concave (tibia) on convex (Talus) roll and slide opposite direction, with the pivot point being in the mid talus.
- In both plantar or dorsi flexion, the tibia and talus passively allow movement from the foot. The Tibia slides anteriorly on superior talus. Talus rolls posteriorly on calcaneum. Talocrural joint
- Anticlockwise roll and slide on Dorsiflexion.
Clockwise roll and slide on Plantar flexion
Form closure
uses the shape of one bone in relation to bones to provide stability to the surrounding joints. For mobility to occur further joint compression and stabilisation is required to withstand a vertical load.
* Force closure is the term used to describe the other forces such as the ligaments and muscles acting across the joint to create stability.
* Superior Talus is convex, inferior talus is concave, superior calcaneum is convex.
* This is a form closure.
* The medial and lateral ligaments create Force closure.
Key stone
In arches of the foot, talas and cuboid on lateral side. Allows for stability, locks in joints and structures around it but also allows for a lot of movement. Example of form and force closure.
Staples
Tiny individual ligaments that link one tarsal bone to another, cuneiforms, navicular and metatarsals.
Beam
Plantar ligaments and plantar fascia
Suspension
Peroneus longus, connects from head of fibula to underneath the lateral border of the foot to the plantar surface of the medial cuneiform. Acts like a stirrup.
What is the point of these arches
Arches of the foot allow for propulsion and ability to walk on different surfaces.
How the plantar fascia supports foot function
- The plantar fascia increases the stability during weight bearing and locomotion.
- Acts like a ligament but is less flexible.
- Due to proximity to plantar surface it has greater leverage and shock absorption.
- It has limited flexibility, but by being attached to heel and toes only it stabilises and supports the twisting mechanism of arches.
Neurological mechanisms involved – EXAM Q
Always consider;
Central control
Local control
Corrective measures and feedback loops
Extrapyramidal system
Basal Ganglia
Sensory feedback
Central control
Brain and spinal cord, some decisions deliciated down to inter neurons there. Dictates and initiates signals sent. Includes motor cortex and cerebellum.
Local control
spinal nerves as they descend into Peripheral nerves and their interaction with muscles and ligaments.
Corrective measures & feedback loops
- Feedback/forward
- Control muscle tone and posture. They maintain postural equilibrium via active adaptation. Eg- Hip shift on walking
Extrapyramidal system and Basal ganglia
- Control muscle tone and posture. They maintain postural equilibrium via active adaptation. Eg- Hip shift on walking
Basal Ganglia – smooth out motor behaviour and inhibit unwanted movements
Sensory feedback
via visual, vestibular and proprioceptive
mechanisms
Talus anatomy
- Articulates directly with tibia and fibula and calcaneus. No muscular attachments, responds passively to everything around it.
- 3 facets, Anterior, middle and posterior
- Convex surface superiorly and a concave surface inferiorly
- Hugely dependent on its ligaments, Interosseous talocalcaneal lig and cervical lig - two that attach the inferior talus to superior calcaneum that we can’t get anywhere near, act the same as the cruciate ligs in the knee. Common football, rugby or hockey injuries, from shearing or traction strain, whole body weight goes forward but boot/studs stay stuck in the ground. Traction through subtalar joint, ankles never really seem to get better.
Role of Talus
- The talus acts as a torque converter, causing rotations of the leg to be converted to inversion and eversion vectors in the foot.
- This is essential for adaptation of the foot to ground reaction forces and loose pack positioning after heel strike.
- It locks the structures of the foot and ankle during toe off to create a stable base for weight bearing and propulsion.
Structural relationships
how the anatomy supports weight distribution through the foot during walking.
Structural relationships - Talocrural joint
- The posterior inferior transverse ligament has a deep portion covered by hyaline cartilage and forms part of the articular surface of talocrural joint.
- The vulnerability of the Talocrural joint is that it has no direct muscle attachments and it’s domed/wedge like shape. It is totally dependent on ligamentous support to prevent anterior/posterior displacement of leg on talus, excessive inversion/eversion (imagine a bosu ball)
Structural relationships - Sinus tarsi
The secret ligament: Interosseus talocalcaneal ligament and cervical ligament, this lies in the sinus tarsi. (similar to the cruciate ligaments of the knee)
* The space between the talus and the calcaneus is the sinus tarsi.
* This space is filled with connective and adipose tissue, richly innervated with mechanoreceptors and free nerve endings.
* Important area for proprioception.
* Inferior extensor retinaculum lies over the lateral aspect of the sinus tarsi.
Weight distribution through foot during walking
The role of the arches during walking
- The longitudinal arches (med and lat) act like a twisting flexible ruler.
- Increased twist on med arch leads to inversion, whilst decrease twist leads to eversion.
- This control on med arch allows small joints of foot to be stabilised during propulsion and intrinsic muscles to produce leverage during propulsion.
- This is supported by long and short plantar ligaments and action of Tibialis anterior and posterior.
- The lateral arch relies on the ‘keystone’ role of the cuboid for stability.
Repetitive injuries to the foot
- Morton’s neuroma – Transverse arch drops, Mainly on toes 2-4 plantar nerves that travel between metatarsals have all the weight of the body on them, become sensitised, thicken and cause Morton’s neuroma. Affects people most who are working on their feet all day e.g retail.
- Plantar fasciitis – Most common in middle aged women, diabetics or people who were high heels frequently.
- Heel spur
- Calcified Achilles tendon
other injuries to the foot
Systemic - Gout
Congenital – Talipes or club foot
Developmental – Sever’s disease, failure of the growth plate as the Achilles attaches onto it. Normally early or pre Adolescents.
Degenerative – Bunions
Neurological:
* UMNL; stroke
* LMNL; foot drop
