FUNCTIONAL ANATOMY: LOWER LIMB & ANKLE

What does this area of the Tibia sit on

Articular surfaces for Talus

All about the Proximal Tibiofibular Joint

• synovial planar joint

• articulation between the head of the fibula and the lateral condyle of the tibia

• held together by ASTFL and PSTFL and interosseous membrane

All about the Distal Tibiofibular Joint

• Fibrous syndesmoses joint

• articulation between the distal fibula and tibia

• held together by AITFL (anterior tibiofibular ligament) and PITFL (posterior tibiofibular ligament) and interosseous membrane

What are these holes in the Interosseous Membrane?

• Apertures

  • they are for neurovascular structures

Talocrural Joint

• synovial hinge joint

  • facilitates DF and PF

• articulation between fibula, tibia, surface of talus

• held together by fibrous synovial and collateral ligaments

All about the Talus

• has a wider body anteriorly than posteriorly

• has a convex superior surface (body)

  • for DF and PF

• has a convex anterior surface (head)

  • articulates with the navicular

Why is the Talar neck depressed?

Allows the joint to go into deeper DF

Medial Ligaments of the Talocrural Joint

Deltoid Ligamet: Anterior Tibiotalar, Tibionavicular, Tibiocalcaneal, Posterior Tibiotalar

About the deltoid ligament

• fans out from the medial malleolus

• limits talar eversion, lateral translation, and rotation

• Anterior fibres = limit PF

• Posteiror fibres = limit DF

Lateral Ligaments of the Talocural joint

1. anterior talofibular

2. posterior talofibular

3. calcaneofibular

Anterior talofibular

• goes from lateral malleolus to talus

• limits inversion and PF

Posterior talofibular

• goes from lateral malleolus to talus

• limits inversions, and DF

Calcaneofibular

• goes from lateral malleolus to calcaneus

• limits inversion

Subtalar Joint

• synovial ellipsoid joint

• inversion/eversion and some abduction/adduction

Popliteal Fossa

• superior border: hamstrings

• Inferior border: gastrocnemius

• contents:

  • plantaris muscle

  • tibial and common fibular nerves

  • popliteal vein

  • popliteal artery

All about the Interosseous Membrane

• links the fibula and tibia together

• provides surface for muscular attachment

• separates the anterior and posterior compartments

Anterior Compartment Muscles

Tibialis anterior

Extensor Hallucis Longus

Extensor Digitorum Longus

Fibularis (peroneus) Tertius

Tibialis Anterior

O: lateral tibial condyle, proximal shaft of tibia, interosseous membrane

I: medial coneiform and 1st MT

A: DF and inversion, support medial longitudinal arch

Extensor Hallucis Longus

O: mid-anterior surface of fibula, interosseous membrane

I: base of distal phalanx of big toe

A: extension of MTP and IP joints of big toe, DF of foot

Extensor Digitorum Longus

O: lateral tibial condyle, interosseous membrane, proximal 2/3 anterior fibula

I: base of middle and distal phalanges of lateral 4 toes via dorsal digital expansions

A: extension of MTP, PIP, DIP joints of lateral 4 toes, DF and eversion of foot

Fibularis (peroneus) tertius

O: distal 1/3 of anterior fibula

I: base of 5th metatarsal

A: DF and eversion of foot

Nerve innervation of Anterior Compartment

Deep Peroneal Nerve

Extensor Retinaculum

• There is a superior and inferior extensor retinaculum

Lateral compartment muscles

Fibularis (peroneus) longus

Fibularis (peroneus) brevis

FIbularis (peroneus) longus

O: head and proximal 2/3 of lateral fibula

I: medial cuneiform and 1st metatarsal

A: eversion and plantar flexion of foot, support arches of foot

Fibularis (peroneus) brevis

O: distal 2/3 lateral fibula

I: 5th metatarsal

A: eversion and assistes in PF of foot

Nerve innervation of lateral compartment

Superficial Peroneal Nerve

Posterior compartment muscles

Gastrocnemius

Plantaris

Soleus

Tibialis Posterior

Flexor digitorum longus

Flexor Hallucis Longus

Gastrocnemius

O: 2 heads originate from superior medial and lateral femoral condyles posteriorly

I: posterior calcaneus via calcaneal tendon

A: PF of foots, assist with knee flexion

Plantaris

O: lateral supracondylar line, oblique popliteal ligament

I: posterior calcaneus via calcaneal tendon

A: weak PF of foot and flexion of knee

Soleus

O: proximal 2/3 of posterior tibia and fibula

I: posterior calcaneus via calcaneal tendon

A: plantar flexion of foot

Tibialis posterior

O: proximal ½ of posterior tibia and fibula, interosseous membrane

I: navicular tuberosity and medial cuneiform

A: PF and inversion of foot, dynamic foot arch support

Flexor digitorum longus

O: proximal middle 1/3 of posterior tibia

I: bases of distal phalanges of lateral 4 toes

A: flexion of MTP, PIP, DIP joints of lateral 4 toes, PF and inversion of foot

Flexor Hallucis longus

O: proximal middle 1/3 of fibula and interosseous membrane

I: base of distal phalange of the big toe

A: flexion of MTP and IP joints of big toe, PF and inversion of foot

Innervation of Posterior Compartment

Tibial Nerve

Flexor Retinaculum

Tom, Dick, and Harry (anterior to posterior) (medial to lateral), tibial nerve pass posterior to the medial malleolus

Blood supply to lower leg (posteriorly)

Femoral Artery

• passes through the adductor hiatus and becomes the popliteal artery behind the knee

• bifurcates and continues down as the posterior tibial artery superficial to TDH and deep to gastroc/soleus

• passes through flexor retinaculum

Blood supply to lower leg (anteriorly)

Femoral artery

• passes through adductor hiatus to become the popliteal artery behind the kee

• bifurcates and passes through superior hiatus and continues down anterior leg as the anterior tibial artery deep to the tib ant

• continues as dorsalis pedis artery lateral to extensor hallucis longus

Posterior Thigh Nerve innervation

Sciatic Nerve (L4-S3)

• enters gluteal region through greater sciatic foramen (inferior to piriformis)

• runs posterior to adductor magnus muscle and splits as tibial and common fibular nerve

innvervates (motor):

• bicerps femoris

• semitendinosus

• semimebranosus

• adductor magnus

Tibial nerve innervation

• descends posterior leg, superficial to TDH and deep to gastroc/soleus

Innervates:

Motor:

• popliteus, plantaris, gastrocs, soleus, tibialis posterior, flexor digitroum longus, flexor hallucis longus

sensory:

• posterolateral lower leg, pinky toes, sole of foot via plantar nerves

Common peroneal nerve innervation

• bifurcates into the deep and superficial fibular nerves

motor:

• short head of biceps femoris

sensory:

• lateral aspect of proximal lower leg

Common peroneal nerve innervation

• runs between peroneus longus and brevis

motor:

• peroneus longus and brevis

sensory:

• anterior aspect of distal lower leg and dorsum of foot

Deep Peroneal Nerve innervation

• runs deep to extensor digitorum longus and tibialis anterior

motor:

• tibialis anterior, EHL, EHB, EDL, EDB, peroneus tertius

sensory:

• between 1st and 2nd toes

Innervation overview (photo)