Plantar Foot: Part 2 Flashcards
2nd plantar layer
- 5 muscles (4 lumbricals, quadratus plantae)
- 2 tendons (FDL and FHL)
- All muscles attach to FDL
Quadratus plantae (flexor accesorius)
- Deep to FDB
- 2 heads (medial and lateral)
Quadratus plantae (flexor accesorius) origins
- Medial head: medial surface of calcaneus
- Lateral head: trigonum plantare and inferior calcaneus (distal to lateral tubercle)
- Origins separated by long plantar ligament
Quadratus plantae (flexor accesorius) insertion
- Heads unite
- Insert onto the FDL tendon
Quadratus plantae (flexor accesorius) blood supply
- Medial and lateral plantar arteries
Quadratus plantae (flexor accesorius) innervation
- Lateral plantar nerve
Quadratus plantae (flexor accesorius) function
- Redirects line of pull of FDL
- Assists in flexing phalanges
Lumbricals (lumbricale muscles)
- 1 is unipennate
- 2,3,4 are bipennate
Lumbricals (lumbricale muscles) origins
- 1st: medial side of 1st tendon of FDL (tendon going to 2nd digit)
- 2-4: adjacent tendons (e.g. 3rd lumbrical: medial side of 3rd, lateral side of 2nd; 2nd lumbrical medial side of 2, lateral side of 1)
- Tendons pass distally plantar to the deep transverse metatarsal ligament
Lumbricals (lumbricale muscles) insertions
- Medial aspect of extensor wing of the extensor expansion at base of proximal phalanx of digits 2-5
- 1st lumbrical goes to 2nd digit, 2nd lumbrical to 3rd digit…
Lumbricals (lumbricale muscles) blood supply
- Respective plantar metatarsal arteries
Lumbricals (lumbricale muscles) innervations
- 1st: medial plantar nerve
- 2-4: deep branch of lateral plantar nerve
Lumbricals (lumbricale muscles) function
- Flex MTP joints
- Extend PIP and DIP joints
3rd plantar layer muscles
- FHB
- FDMB
- ADD Hallucis
Flexor hallucis brevis origins
- Lateral head: plantar surface of cuboid and lateral cuneiform
- Medial head: tibialis posterior tendon
Flexor hallucis brevis insertions
- Medial and lateral base of proximal phalanx
- Respective heads invest respective hallux sesamoid bones before phalangeal insertion: medial (tibial) and lateral (fibular)
- Sesamoids
Flexor hallucis brevis blood supply
- 1st plantar metatarsal artery
Flexor hallucis brevis innervation
- Medial plantar nerve
Flexor hallucis brevis function
- Flex (plantarflex) hallux MTP joint
Flexor hallucis brevis sesamoid insertion advantage
- Increase the mechanical advantage of the FHB
- Weight bearing structures and decrease friction
Flexor digiti minimi brevis origin
- Base of 5th metatarsal
- Tendon sheath of fibularis longus
Flexor digiti minimi brevis insertion
- Plantar/lateral aspect of base of proximal phalanx of 5th toe
Flexor digiti minimi brevis bloody supply
- Lateral plantar artery
Flexor digiti minimi brevis innervation
- Superficial branch of lateral plantar nerve
Flexor digiti minimi brevis function
- Flex (plantarflex) 5th digit at MTP joint
Adductor hallucis heads
- Transverse
- Olbique
Adductor hallucis transverse head origin
- Fibrous capsule
- Plantar plates of digits 3-5
- Deep transverse metatarsal ligament
Adductor hallucis oblique head origin
- Plantar aspect of metatarsal bases 2-4
- Fibularis longus tendon sheath
Adductor hallucis insertion
- Lateral sesamoid
- Lateral aspect of proximal phalanx base of 1st digit
Adductor hallucis blood supply
- Plantar metatarsal arteries
Adductor hallucis innervation
- Deep branch of lateral plantar nerve
Adductor hallucis function
- Adducts hallux
Opponens digiti minimi origin
- Base of 5th metatarsal
- Long plantar ligament
- FDMB
Opponens digiti minimi insertion
- Lateral shaft of 5th metatarsal
- Surrounding fascia
Opponens digiti minimi function
- Abduct and flexion 5th toe
4th plantar layer
- 4 dorsal and 3 plantar interossei (two muscle groups of 4th layer)
- Located within the metatarsal spaces
- None associated with hallux
- Tendons pass dorsal to deep transverse metatarsal ligament
Interosseous muscle groups
- 3 plantar ADDuct
- 4 dorsal ABduct
2 tendons of 4th layer
- Tibialis posterior
- Fibularis longus
Plantar interossei muscles
- 3 in number
- Associated with digits 3,4,5
- Unipennate muscles
Plantar interossei origins
- Base and medial aspect of shafts of metatarsals 3, 4, 5
Plantar interossei insertions
- Medial aspect of base of proximal phalanx
- Extensor expansion of same digit
- Example: 1st plantar interossei originates from the 3rd metatarsal and inserts onto the proximal phalanx and extensor expansion of 3rd digit.
- 2nd plantar interossei – 4th digit; 3rd – 5th digit
Plantar interossei blood suply
- Plantar metatarsal arteries 2-4
Plantar interossei innervation
- Lateral plantar nerve
- Superficial branch innervates
3rd plantar interossei - Deep branch innervates 1st and 2nd plantar interossei
Plantar interossei functon
- Adduct digits 3-5 toward foot midline
- Flex (plantarflex) 3-5 MTP joint
- Extend (dorsiflex) IP joints of digits 3-5
Dorsal interossei
- 4 in number
- Associated with digits 2-4
- Digit 2 has 2 dorsal interossei muscles inserting
- Bipennate muscles located within the intermetatarsal space
Dorsal interossei origins
- Adjacent metatarsal shafts
- Example: 1st dorsal interossei originates lateral aspect of 1st metatarsal shaft and medial aspect of 2nd metatarsal shaft
Dorsal interossei insertions
- 1st dorsal interossei: medial aspect of base of proximal phalanx and extensor expansion of 2nd digit
- 2nd-4th dorsal interossei: lateral aspect of base of proximal phalanx and extensor expansion of corresponding digit
Dorsal interossei blood supply
- Corresponding dorsal metatarsal artery
Dorsal interossei innervation
- Lateral plantar nerve
- Deep branch of lateral plantar nerve innervates 1st-3rd
- Superficial branch of lateral plantar nerve innervates 4th
- 1st and 2nd also receives innervation from deep fibular nerve
Dorsal interossei function
- Abducts digits 2-4
- Flex (plantarflex) MTP joints
- Extend (dorsiflex) IP joints
Intermetatarsal spaces
- 1st: 1st dorsal interosseous
- 2nd: 2nd dorsal, 1st plantar
- 3rd: 3rd dorsal, 2nd plantar
- 4th : 4th dorsal, 3rd plantar
Flexor sheath
- Fibrous
- Keeps the tendons anchored to the bone
- FHL, FDB and FDL are surrounded by a synovial sheath to reduce friction
- Vincula brevia and vincula longa
Extensor expansion
- Tendinofibroaponeurotic structure
- Involved in the extensor function of the digits
Extensor expansion formed by
- Extrinsic muscles
- Intrinsic muscles
- Stabilizing ligaments
Extrinsic muscles contributing to extensor expansion
- EDL
- EHL
Intrinsic muscles contributing to extensor expansion
- EDB
- Lumbricals
- Interossei
Stabilizing ligaments contributing to extensor expansion
- Sling and wing
- Triangular lamina
Sling
- Proximally located
- Transversely oriented fibers
- Pass around the MTP joint
- Interossei insert into the sling
- Anchors EDL allowing it to extend all digits
Sling attachment points
- Plantar plate
- Deep transverse metatarsal ligament
Wing
- Distal portion of extensor expansion
- Fibers are oriented obliquely (triangular shaped)
- Located at the proximal phalanx
- Lumbricals insert into the medial side of the wing
EDL tendons
- Forms the central axis of extensor expansion
- Stabilized by the sling at the MTP joint
- Divides into 3 slips (trifurcates) at the MTP joint (some say proximal phalanx)
3 slips of EDL tendons attachment points
- Medial/lateral slips: extend over dorsum of middle phalanx, insert into base of distal phalanx as a terminal tendon
- Middle slip: inserts into base of middle phalanx
Triangular lamina
- Found between lateral slips of EDL
- Function is not known
- Believed to anchor medial and lateral slips
- Keeps them from sliding plantarward
EDB and EHB tendons]
- EDB joins the EDL tendon
- EDB tendons can form lateral slip instead of EDL
- EHB attaches to base of proximal phalanx
Lumbrical tendons
- Pass plantar to deep transverse metatarsal ligament
- Insert into wing
- This allows them to flex MTP joint and extend IP joints
- Can form medial slip
Interosseous tendons
- Pass dorsal to deep transverse metatarsal ligament
- Insert into base of proximal phalanx at the tubercle
- Insert into extensor apparatus at the sling
- Disputed by some
