A review of the ankle and foot (Part 1): Anatomy

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In prep for my first week as a full-time employed physical therapist I started reviewing the ankle and foot… thank you Dutton for the all-encompassing reference. It might sound odd why I would chose the ankle out of all body parts to start. It’s simple; referral source driven, like most things. So me being the young, diligent, type A person I am what else would I do but read Chapter 21 “The Ankle and Foot” by Mark Dutton so that I may try and perform at an above satisfactory level come Monday. In the midst of my efforts I decided to turn it into an opportunity for me to construct and share a review of this difficult yet amazing anatomical structure that humbly allows us to walk all over it. (pun intended)

Part 1: Anatomy (this post)

Part 2: Biomechanics and Pathology (next…)

Let me start with some of the statistics about the ankle and foot to demonstrate its awesomeness.

-The ankle and foot make up 14% of the bones in the whole body totally 28

-The ankle withstands the most force per surface area making it the strongest joint able to take on 275% of body weight while running.

-Each foot absorbs 121.5 tons running 1 mile. Equivalent to 17 African Bull Elephants. (Multiple that by 26.2 miles for those marathoners)

-60% of the total force above is absorbed through the rear-foot and 40% thru the mid and forefoot. ( Yes… I’m sure there is debate about rear-foot strike vs. mid-foot strike vs.forefoot strike)

For you runners more statistics here

Anatomical Review 

It has been awhile since anatomy, which to me I view as the foundation of physical therapy so its always refreshing when revisiting basic anatomy.

Bones

Rearfoot: “Its the coach of the foot”- A distant memory from PT school. This is due to the rearfoot’s influence on biomechanics and function of the midfoot and forefoot. Consisting of the tibiofibular jt, talocrural jt, and the subtalar jt.

Midfoot: adds to stability, and transmits motion from rearfoot to front foot. Like your drive shaft (of a car) transmits motion from your rear axles to the front axles. (now thats bio-mechanics). Consisting of talocalcaneonavicular jt, cuneonavicular jt, cuboideonavicular jt, intercuneiform, cuneocuboid jt, and the calcaneocuboid jt.

Forefoot: Its occupation is to adapt to the terrain once in contact and the work is coming from the tarsometatarsal jts, intermetatarsal jts, the metatarsophalangeal jts, and interphalangeal joints.

Ligaments 

Lateral Collateral Ligaments. Providing primary stability to the subtalar joint.

-Anterior Talofibular Ligament (Test integrity with anterior drawer test): Runs from anterior fibular malleolus to talus. With plantarflexion of the ankle ATFL resists ankle inversion. Also resists anterior translation of the talus from ankle mortise.

-Calcaneofibular Ligament (Test integrity with talar-tilt test): Runs from fibular malleolus to calcaneus. Resists inversion. CFL resists inversion more in ankle dorsiflexion and ATFL resists inversion more in plantarflexion.

-Posterior Talofibular Ligament (No specific clinical test; typically not injured in isolation). This strong ligament assists in resisting inversion in full dorsiflexion with its fibers running horizontally from posterior talus to posterior-distal fibula.

Medial Collateral Ligaments (Deltoid ligament due to the triangular shape it forms)

-Tibionavicular Fibers: runs superior to inferior from the med. malleolus to the navicular bone

-Posterior tibiotalar fibers: runs posteriolateral from med. malleolus to the medial talus.

-Tibiocalcaneal fibers: travels from med. malleolus to the sustentaculum tali.

-Anterior tibiotalar fibers: run anteriorly from med. malleolus to medial surface of talus.

Ranking the above ankle ligaments from weakest to strongest: ATFL, PTFL, CFL, Deltoid Ligament Complex.

Muscles by Compartment

  Caution: The major annoyance (I experienced in PT school) of different sources having different nerve roots for the same muscle may be experienced here. All readers should understand that nerve roots supplying muscles do overlap and vary slightly. Dutton’s Orthopedic Examination, Eval, and Intervention book was used as this particular source for the following nerve roots. 

Anterior Compartment (Dorsiflexors of the Ankle)

Tibialis Anterior (Deep Peroneal N. L4-L5):

Origin- lat. tibial condyle, proximal half of lateral tibial crest, and interosseous membrane.

Insertion: 1st cuneiform bone and Medial/Planar surface of 1st metatarsal.

Extensor Digitorum Longus (Deep Peroneal N. L5-S1):

Origin- Lat condyle of tibia, and proximal anterior shaft of fibula

Insertion- 1 tendon into each lateral four toes

Extensor Hallucis Longus (Deep Peroneal N. L5-S1):

Origin- Middle anterior half of fibular shaft

Insertion-Base of distal phalanx great toe

Peroneus Tertius (Deep Peroneal N. L5-S1) 

Origin- lateral Slip of Extensor Digitorum Longus

Insertion- Tuberosity of the 5th metatarsal

Lateral Compartment (Evertors of the Ankle)

Peroneus Longus (Superficial Peroneal N. L5-S1)

Origin- Lat condyle of the tibia, head, and proximal 2/3 of fibula

Insertion- Base of the first metatarsal and lateral side of first cuneiform

Peroneus Brevis (Superficial Peroneal N. L5-S1) 

Origin- Distal Two-thirds of lateral fibular shaft

Insertion- Tuberosity of the fifth metatarsal

Clinical Pearl: Check out the innervation patterns of each compartment. The Deep Peroneal Nerve is in the anterior compartment thus supplying the dorsiflexor muscles, as the Superficial Peroneal Nerve is in the lateral compartment supplying the evertors. Knowing this helps with differential diagnosis of peripheral nerve injuries.

Superficial Posterior Compartment (Plantarflexors of the Ankle)

Gastrocnemius (Tibial N. S1-S2)

Origin- Medial and lateral condyle of Femur

Insertion- Posterior surface of calcaneus through Achilles Tendon

Plantaris (Tibial N. S1-S2)

Origin- Lateral Supracondylar Line of Femur

Insertion- Postertior surface of calcaneus through Achilles Tendon

Soleus (Tibial N. S1-S2) 

Origin- Head of fibula, proximal third of shaft, midshaft of posterior tibia

Insertion- Posterior surface of calcaneus through Achilles Tendon

Deep Posterior Compartment (Flexors of the Foot)

Tibialis Posterior (Tibial N. L4-L5)

Origin- Posterior surface of the tibia, proximal 2/3 posterior fibula, and interosseous membrane

Insertion- Navicular bone, tendinous expansion to other tarsals and metatarsals (basically everywhere on the plantar-surface of the foot)

Flexor Hallucis Longus (Tibial N. S2-S3) 

Origin- Posterior distal 2/3 of fibula

Insertion- Base of the distal phalanx of the 1st toe

Flexor Digitorum Longus (Tibial N. S2-S3)

Origin- Middle of posterior tibia

Insertion- Distal phalanx of toes 2-5

Intrinsics of the Foot 

The intrinsic muscles of the foot are key in providing support during propulsion. The muscles consist of four layers which are all deep to the plantar fascia. These muscles are innervated by the medial plantar nerve and/or the lateral plantar nerve which are two branches off of the Tibial N.

First Layer (most plantar)

Abductor Hallucis (Medial Plantar N. L5) 

Origin- medial process of calcaneus

Insertion- medial side of the base of proximal phalanx 1st toe.

Abductor Digiti Minimi (Lateral Plantar N. S1-S2)

Origin- Lateral side of 5th metatarsal

Insertion- Proximal phalanx of Fifth digit

Flexor Digitorum Brevis (Medial and Lateral Plantar N. S2-S3)

  Origin- Tuberosity of calcaneus

  Insertion- Tendon slip into each middle phalanx toes 2-5

Second Layer

Flexor Digitorum Accessorius (aka Quadratus Plantae) (Lateral Plantar N. S1-S3) 

Origin- Medial concave surface of calcaneus

Insertion- Tendon of Flexor Digitorum Longus

Lumbricales (1st: Medial Plantar N, Others: Lateral Plantar N. S2-S3)

Origin- adjacent tendons of flexor digitorum longus

Insertion- Dorsal digital expansion of phalanges

Third Layer

Flexor Hallucis Brevis (Medial Plantar Nerve S1-S2)

  Origin- Medial part of plantar surface of cuboid and adjacent part of lateral cuneiform

Insertion- Sides of base of proximal phalanx

Adductor Hallucis (Lateral Plantar Nerve S2-S3)

Oblique Head:

Origin: Base of Metatarsals 2-4.

Insertion: Lateral sesamoid bone of hallux and 1st phalanx

  Transverse Head

Origin: Transverse metatarsal ligaments of MTP ligaments 3-4

Insertion: Lateral sesamoid bone

Flexor Digiti Minimi Brevis (lateral Plantar N. S2-S3)

Origin- Medial plantar surface 5th metatarsal

Insertion- lateral/base of 5th digit

Fourth Layer

Dorsal Interossei (Lateral Plantar N. S2-S3)

Origin- Sides of adjacent metatarsal bones

Insertion- Proximal phalanges and dorsal expansions 2-4

Plantar Interossei (Lateral Plantar N. S2-S3)

Origin- Base of medial sides metatarsals digits 3-5

Insertion- Dorsal Digit Expansions and proximal phalanges 3-5

Sole of Foot

All of that writing and review absolutely gave me unwanted flash backs of the struggle in anatomy lab. Part 2 will be more on the biomechanics and what happens when things go wrong. Until then i’ll be exploring Europe.

“Nuttin but my Dutton”- Matty D

Study session over…

Stephen Henry

 

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2 thoughts on “A review of the ankle and foot (Part 1): Anatomy

  1. Pingback: Top PTBT Posts of 2015 | PTbraintrust

  2. Pingback: A Year In Review: II | PTbraintrust

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