9/18 Foot Flashcards
Foot osteology: overview
Tarsus
metatarsus (g., after root of foot; 5)
• phalanges (singular=phalanx; g., battle line; 14)
Deep fascia of the foot
- Dorsum of foot: – thin and continuous with extensor retinaculum (superior and inferior)
- Sole of foot: – called plantar fascia – central part thickens to form plantar aponeurosis (g. to become tendinous)
• Plantar aponeurosis
– consists of longitudinally arranged band of dense connective tissue
– arises from calcaneus posteriorly
– covers entire length of sole
– divides into five bands (enclose digital tendons)
– helps support the longitudinal foot arches
Clinical anatomy: plantar fasciitis and “heel spur syndrome”
• ________ inflammation at proximal attachment (calcaneus)
– pain most severe after sitting and getting out of bed
- Causes: – running, high-impact exercise, worn-out shoes, overweight
- Plantar fasciitis may lead to:
– bony process (“heel spur” or “calcaneal spur”) may develop – especially from medial calcaneal tubercle
Plantar aponeurosis
Foot muscles: dorsum of foot
• Two muscles:
- extensor hallucis brevis (1st phalanx)
-
extensor digitorum brevis (2nd-4th phalanges)
- join respective long tendons approximately at the MP Joint
• Innervation:
– deep fibular nerve
• Form a fleshy mass on lateral part of dorsum of foot – anterior to lateral malleolus
Plantar muscles: first layer (3)
• Three short muscles that extend from calcaneus to phalanges:
- abductor digiti minimi
- flexor digitorum brevis
- abductor hallucis
Plantar muscles: second layer (2)
• Quadratus plantae:
– joins tendon of f.d.l. to calcaneus – assists f.d.l. in flexing lateral four digits
• Lumbricals:
– originate from flexor digitorum longus tendons – medial aspect of extensor expansion – flex mp joint – extend pip and dip joints
• Flexor hallucis longus
and flexor digitorum longus tendons located in this layer
– not considered second layer plantar muscles
Plantar muscles: third layer (3)
• Three short muscles to first and fifth digits (anterior half of foot)…
- Flexor digiti minimi brevis
- Adductor hallucis:
– transverse head & oblique head
- Flexor hallucis brevis:
– two heads (medial & lateral) cover plantar surface of first metatarsal – tendons have sesamoid bones
• protect first metatarsal head and tendon of FHL when standing and walking
Plantar muscles: fourth layer
• Consists of interossei between metatarsals:
– three plantar interossei
• “pad” digits 3, 4, & 5 toward 2nd digit
– four dorsal interossei
- “dab” digits 2, 3, & 4 away from midline of 2nd digit
- Fibularis longus and tibialis posterior tendons found in this layer
Plantar Aspect of Foot: Layer 1
abductor digiti minimi
abductor hallucis
flexor digitorum brevis
Plantar Aspect of Foot: Layer 2
lumbricals
quadratus plantae
flexor digitorum longus tendon
flexor hallucis longus tendon
Plantar Aspect of Foot: Layer 3
flexor digiti minimi
adductor hallucis (transverse and oblique head)
flexor hallucis brevis
Plantar Aspect of Foot: Layer 4
interossei (dab and pad)
Fibularis longus tendon
and
tibialis posterior tendon
Clinical notes: hallux valgus, bunion, & corns
• Hallux valgus is a foot deformity characterized by lateral deviation of great toe:
– surrounding tissues swell and resultant pressure and friction against shoe cause a bursa to form
– tender and inflamed bursa is called a bunion
– corns (inflamed areas of thick skin) over proximal interphalangeal joints
Toe Deformities
- Referring to lateral four toes in first three cases below.
- If flexion in the distal IP joint, it is called a mallet toe
- If extension at the MP joint and flexion at the proximal IP joint, it is called a hammer toe
- If extension at the MP joint and flexion at both the proximal and distal IP joint, the deformity is referred to as a claw toe
- If the deformity occurs in the large toe (extend MP, flex IP, it is known as a trigger toe
• All appear a consequence, in part, of shortened flexor muscles which can override lumbrical function
Clinical note: hammer toe
• “Hammerlike” deformity (usually of 2nd digit) in which:
– proximal phalanx is permanently hyperextended at metatarsophalangeal joint
– middle phalanx is plantarflexed at the proximal interphalangeal joint
– distal phalanx is extended
Clinical note: claw toes
• Characterized by:
– hyperextension of metatarso-phalangeal joints
– flexion of the distal and proximal interphalangeal joints
Nerves: sole of foot
• Tibial nerve divides posterior to medial malleolus into:
– medial and lateral plantar nerves:
- supply all intrinsic muscles of the foot (except two intrinsic dorsum muscles)
- supply plantar skin
Cutaneous Innervation Leg: Common Fibular n.
Cutaneous Innervation Leg: Tibial n.
Medial Plantar Nerve
- Larger of the two terminal branches of tibial nerve
- Course:
– passes deep to abductor hallucis
– runs anteriorly between abductor hallucis and flexor digitorum brevis
– terminates near metatarsal bases by dividing into three sensory branches (medial three and a half digits)
Lateral Plantar Nerve
- Smaller of the two terminal branches of tibial nerve
- Course:
– passes deep to abductor hallucis – runs anterolaterally deep to flexor digitorum brevis – terminates by dividing into superficial and deep branches
Plantar Muscle Innervation Summary
Dorsum of Foot: Arteries
Dorsalis pedis runs anteromedially to first interosseous space and divides into:
– arcuate artery – deep plantar artery
Dorsalis Pedis Branches
Plantar Aspect of Foot: Blood Supply
- Derived from posterior tibial artery
- Divides deep to abductor hallucis to form – medial and lateral plantar arteries…
- Medial plantar artery:
– passes distally between abductor hallucis and FDB (not shown) – Gives rise to medial two plantar metatarsal and plantar digital arteries
• Lateral plantar artery: – runs with lateral plantar nerve (superficial to quadratus plantae) – terminates by joining deep plantar artery forming the plantar arterial arch – Gives rise to 3rd-6th plantar metatarsal and plantar digital arteries
Foot arches
- Formed by tarsal and metatarsal bones
- Functions: 1. absorb shock during weightbearing 2. makes foot adaptable to surface and weight changes
- Two foot arches:
- longitudinal arch consists of medial and lateral parts:
– formed by calcaneus, talus, navicular, three cuneiforms, and medial three metatarsals (medial side)
– formed by calcaneus, cuboid, and lateral two metatarsals (lateral side)
- transverse arch
- runs between medial and lateral longitudinal arches
- formed by cuboid, three cuneiforms, and metatarsal bases
