Functional Anatomy 1 - Lecture 14: Leg

leg

• distal to knee and superior to the ankle

• foot/ankle extrinsic muscles

  • muscle belly in the leg with tendon to the foot/ankle

osteology of the leg

tibia: larger, primary weight-bearing bone (90%)

fibula: smaller, less weight-bearing bone (10%)

tibial crest

• anterior-medial surface: no muscle attachments

• anterior-lateral surface: anterior compartment muscles

articulations with fibula

• fibular facet (proximal)

• fibular notch (distal)

soleal line

origin of soleus

• reference for muscle attachments superior and inferior

• inferior-medial direction

• merges with medial border of tibia

proximal tibiofibular joint

synovial plane joint

• two surfaces sliding on each other (tibia+fibia)

ligaments

• anterior/posterior ligaments of fibular head provide stability

distal tibiofibular joint

• fibrous joint (syndesmosis)

• ligaments

  • interosseous membrane (IO)

  • anterior tibiofibular ligament

  • posterior tibiofibular ligament

distal tibiofibular joint

• syndesmotic ankle sprain

  • high ankle sprain

• forced dorsiflexion with rotation

  • damages anterior/posterior tibiofibular ligaments, possible IO membrane

forefoot

phalanges, metatarsal bones

midfoot

medial/intermediate/lateral cuneiform bones, cuboid bone, navicular bone

hindfoot

talus, calcaneus

talus

• plantarflex ankle, palpate anterior/inferior to the malleoli

  • brings talar dome anteriorly

medial talar dome

plantarflex and evert the hindfoot

lateral talar dome

plantarflex and invert the hindfoot

calcaneal tuberosity

forms heel: Achille’s tendon attachment

sustentaculum tali

about 1 finger’s breadth distal to the tip of medial malleolus

navicular tuberosity

felt approximately 2 cm anterior to sustentaculum tali, prominent tubercle on medial aspect of foot

• tibialis posterior attachment

tuberosity of 5th MT

• prominence on lateral aspect of foot, lateral to base of 5th MT

  • peroneus brevis attachment

ankle movement

• dorsiflexion/plantarflexion

  • sagittal plane (ML axis)

• inversion/eversion

  • frontal plane (AP axis)

• abduction/adduction

  • transverse plane (SI axis)

leg region innervation

sciatic (L4-S3)

• superior angle of popliteal fossa

• common peroneal (fibular) (L4-S2)

  • superficial peroneal (fibular) (L4-S2)

  • deep peroneal (fibular) (L4-S1)

• tibial (L4-S3)

leg sensory innervation

peripheral cutaneous innervation

• medial knee and medial leg

  • saphenous n (cutaneous branch from femoral n)

• lateral knee and leg

  • lateral sural cutaneous (branch from common peroneal n)

• anterior lateral lower leg and some dorsal foot

  • superficial peroneal (fibular) n

• posterior middle leg

  • sural cutaneous n (combined branches from tibial n and common peroneal n

• webspace between 1st and 2nd digit

  • deep peroneal (fibular n)

dermatomes sensory innervation of leg

L1: groin region near inguinal ligament

L2: superior-anterior thigh to lateral thigh

L3: distal anterior thigh to medial thigh

L4: medial lower leg

L5: lateral lower leg

S1: lateral foot/posterior medial thigh

S2: posterior lower leg/posterior medial thigh

leg region arteries

• popliteal a.

  • anterior tibial a.

    • anterior through gap in interosseous membrane

    • deep anterior compartment between tibialis anterior and EDL → dorsalis pedis a.

  • posterior tibial a.

    • deep posterior compartment

    • posterior to medial malleolus

  • peroneal (fibular a.)

    • supplies lateral compartment

    • descends near FHL

leg region veins

superficial veins

• great saphenous v.

  • medial lower leg

  • to femoral v. in femoral triangle

• small saphenous v.

  • lateral lower leg

  • to popliteal v. in popliteal space

deep veins

• bundled with arteries, share a name

3 compartments of leg

• anterior

• lateral

• posterior

  • superficial

  • deep

divided by:

• interosseous membrane

• anterior intermuscular septum

• lateral intermuscular septum

anterior compartment

• anterior to interosseous membrane lateral to tibial shaft and medial fibular shaft/anterior intermuscular septum

• deep peroneal (fibular) n.

• anterior tibial a.

• ankle dorsiflexion (with eversion/inversion): digit extension

  • tibialis anterior

  • extensor hallucis

  • extensor digitorum longus

  • peroneus (fibularis) tertius

tibialis anterior

O: lateral tibial epicondyle and proximal 2/3 of lateral tibia and IO membrane

I: medial and inferior surfaces of medial cuneiform, base of 1st metatarsal

A: ankle dorsiflexion and inversion, assists with supporting medial longitudinal arch of foot during weight bearing positions

N: deep peroneal (fibular) n. (L4-L5)

B: anterior tibial artery

extensor hallucis longus

O: middle part of anterior surface fibula and IO membrane

I: dorsal base of distal phalanx of 1st digit

A: extension 1st digit, ankle dorsiflexion

N: deep peroneal (fibular) n. (L5-S1)

B: anterior tibial artery

extensor digitorum longus

O: lateral condyle of tibia, proximal 2/3 of anterior fibula, IO membrane

I: middle and distal phalanges of digits 2-5 (extensor hood)

A: extension of digits 2-5, ankle dorsiflexion

N: deep peroneal (fibular) n. (L5-S1)
B: anterior tibial artery

peroneus tertius

O: distal third of anterior surface of fibula and IO membrane

I: dorsal base of 5th metatarsal

A: ankle dorsiflexion and eversion

N: deep peroneal (fibular) n. (L5-S1)

B: anterior tibial a.

extensor retinaculum

needed to support line of pull of anterior compartment muscles and prevent bowstringing of tendons across the ankle

superior extensor retinaculum

between tibia and fibula

inferior extensor retinaculum

Y shaped from calcaneus to

• medial malleolus

• plantar fascia

lateral compartment of leg

• lateral fibula to anterior and posterior intermuscular septum

• ankle eversion

• superficial peroneal n.

• peroneal artery

peroneus (fibularis) longus

O: head of fibula and proximal 2/3 of lateral fibula

I: plantar base of 1st metatarsal and medial cuneiform
A: ankle eversion and plantarflexion, support arches of foot
N: superficial peroneal n. (L5, S1, S2)
B: peroneal artery

peroneus (fibularis) brevis

O: middle part of lateral fibula

I: tuberosity of 5th MT

A: ankle eversion and plantarflexion

N: superficial peroneal (fibular) n. (L5, S1, S2)

B: peroneal (fibular) a.

peroneal (fibular) retinaculum

supports stabilization of peroneal tendons as they cross lateral malleolus

• superior: calcaneus to lateral malleolus

• inferior: calcaneus to inferior extensor retinaculum

posterior compartment

• posterior to interosseous membrane, tibia, fibular, and posterior intermuscular septum

• further divided into superficial and deep by transverse intermuscular septum

• ankle plantarflexion; digit flexion

• tibial nerve

• posterior tibial artery

superficial posterior compartment

• gastrocnemius (medial and lateral heads)

• plantaris

• soleus

deep posterior compartment

• flexor digitorum longus (medial)

• tibialis posterior (middle)

• flexor hallucis longus (lateral)

triceps surae

gastrocnemius, plantaris, soleus

• common attachment to calcaneus via calcaneal tendon

• generate up to 93% of plantarflexion force

• superficial posterior compartment

gastrocnemius

O:

• lateral head: lateral femoral condyle

• medial head: medial femoral condyle and popliteal surface of femur

I: posterior calcaneus via Achilles tendon

A: ankle plantarflexion; knee flexion

N: tibial nerve (S1-S2)

B: posterior tibial artery

plantaris

O: inferior part of lateral supracondylar line femur

I: posterior calcaneus via Achilles tendon

A: weak ankle plantarflexion; knee flexion

N: tibial nerve (S1-S2)
B: posterior tibial artery

soleus

O: posterior head of fibula, superior posterior fibula, soleal line of tibia

I: posterior calcaneus via Achilles tendon

A: ankle plantarflexion
N: tibial nerve (S1-S2)

B: posterior tibial a.

tibialis posterior

O: IO membrane, posterior surface of tibia inferior to soleal line, posterior fibula

I: tuberosity of navicular, cuneiforms, cuboid, bases of MT 2-4

A: ankle plantarflexion and inversion

N: tibial nerve (L4-L5)

B: posterior tibial artery

flexor digitorum longus

O: medial posterior tibial inferior to soleal line

I: base of distal phalanges 2-5

A: flexion of MTPs and IPs 2-5, weak ankle plantarflexion and inversion

N: tibial nerve (S2-S3)

B: posterior tibial artery

flexor hallucis longus

O: distal 2/3 posterior fibula and part of IO membrane

I: base of distal phalanx of 1st digit

A: flexion of 1st digit MTP and IP; weak ankle plantarflexion and inversion

N: tibial nerve (S2-S3)

B: posterior tibial artery

• tibialis posterior

• flexor digitorum longus

• posterior tibial artery

• tibial nerve

• flexor hallucis longus

Tom, Dick, And Nervous Harry

flexor retinaculum

supports stabilization of deep posterior tendons as they cross medial malleolus

• calcaneus to medial malleolus

tarsal tunnel

tarsal tunnel syndrome

narrowing of the tarsal tunnel, compression of the tibial nerve/posterior tibial artery

grooves

bony _____ for deep posterior muscle tendons

medial grooves

for tibialis posterior, flexor digitorum longus, flexor hallucis longus

lateral grooves

for peroneus longus/brevis

popliteus

O: lateral surface of lateral condyle of femur, lateral meniscus (intra-capsular)

I: posterior tibia superior to soleal line

A: internal rotation of the knee, flexion of the knee

N: tibial nerve (L4-S1)

B: posterior tibial artery