REGION: FOOT – Anatomy & Physiology

Studying anatomy & physiology grouped by regions of the body.

WORK IN PROGRESS…LAST UPDATE 01.22.2020

Bones of the Foot

Talus	Cuneiform: lateral, intermediate, medial
Calcaneus	Metatarsals
Navicular	Phalanges: proximal, middle, distal
Cuboid

Talus. Posterior process of talus. Body of talus. Neck of talus. Head of talus.	Medial, intermediate, lateral cuneiform.
Calcaneus. Sustentaculum tali. Calcaneal tuberosity. Calcaneal tubercle.	Metatarsals 1-5. Tuberosity of 5^th metatarsal.
Navicular (boat, medial). Navicular tuberosity.	Proximal phalanges 1-5. Middle phalanges 2-5. Distal phalanges 1-5.
Cuboid (lateral). Tuberosity of cuboid.

Layer 1: Superficial Plantar Muscles of the Foot

Flexor digitorum longus	posterior surface of tibia.	distal phalanges of toes II-V.	ankle plantar flexion, flexion of distal and middle phalanges of toes at interphalangeal joints and proximal phalanx of each toe at metatarsophalangeal joint.
Flexor digitorum brevis	calcaneus, medial calcaneal tuberosity.	sides of plantar surface of middle phalanges, digits 2-5.	flex digits 2-5 at proximal IP joint.
Abductor hallucis	calcaneus, medial calcaneal tuberosity.	base of proximal phalanx of 1st digit.	abduct and flex 1st digit at 1st MTP joint.
Abductor digiti minimi	calcaneus, medial calcaneal tuberosity.	base of proximal phalanx of 5th digit.	abduct and flex 5th digit at MTP joint.

Innervated by: abductor hallucis, flexor digitorum brevis–medial plantar nerve (branch of tibial nerve); abductor digiti minimi–lateral plantar nerve (branch of tibial nerve); ventral rami of S1, S2, S3.

Layer 2: Plantar Muscles of the Foot

Quadratus plantae	calcaneus, medial calcaneal tuberosity.	tendons of flexor digitorum longus (proximal sole).	assist flexor digitorum.
Lumbricals	tendons of flexor digitorum longus.	extensor hoods (medial margin) of digits 2-5.	flexion at MTP joints and extension at IP joints.

Innervation: 1st lumbrical–medial plantar nerve; 2nd-4th lumbricals–lateral plantar nerve; quadratus plantae–lateral plantar nerve.

Quadratus plantae
Lumbricals

Layer 3: Plantar Muscles of the Foot

Flexor hallucis longus	inferior 2/3 of fibula.	distal phalanges of great toe.	ankle plantar flexion, flexion of distal and middle phalanges of toes at interphalangeal joints and proximal phalanx of each toe at metatarsophalangeal joint.
Flexor hallucis brevis	cuboid, lateral cuneiform.	base of proximal phalanx of 1st digit.	flex 1st digit at MTP joint.
Adductor hallucis	transverse head—MTP joints of digits 3-5; oblique head—base of metatarsals 2-5.	base of proximal phalanx of 1st digit (lateral side).	adduct 1st digit at MTP.
Flexor digiti minimi brevis	base of 5th metatarsal.	base of proximal phalanx of 5th digit (lateral side).	flex 5th digit at MTP joint.

Innervation: flexor hallucis brevis–medial plantar nerve (from tibial nerve); lateral plantar nerve (from tibial nerve).

Layer 4: Plantar Muscles of the Foot

Dorsal interossei	sides of adjacent metatarsals.	extensor hoods (and bases of proximal phalanges of digits 2-5).	abduct digits 2-5 at MTP joints.
Plantar interossei	medial sides of metatarsals.	extensor hoods (and bases of proximal phalanges of digits 2-5).	adduct digits 3-5 at MTP joints.

Innervation: lateral plantar nerve.

Superficial Dorsal Muscles

Extensor digitorum brevis	calcaneus (superolateral surface).	tendons of extensor digitorum longus (lateral sides).	extend digits 2-5.
Extensor digitorum longus	lateral condyle of tibia, anterior fibula, interosseous membrane.	middle and distal phalanges of toes II-V.	ankle dorsiflexion, extension of distal and middle phalanges of toes at interphalangeal joints and proximal phalanx of each toe at metatarsophalangeal joint.
Extensor hallucis brevis	calcaneus (superolateral surface).	base of proximal phalanx of 1st digit.	extend metatarsarophoalangeal joint of 1st toe.
Extensor hallucis longus	anterior surface of fibula; interosseous membrane.	distal phalanx of great toe.	ankle dorsiflexion; extension of proximal phalanx of great toe at metatarsophalangeal joint.

Innervated by deep fibular nerve.

Other Muscles

Joints

Talocrural
Talocalcaneal (ankle)
Interphalangeal (IP)
Metatarsophalangeal (MTP)
Tarsometatarsal

Ligaments/Tendons

Tibiocalcaneal
Tibionavicular
Anterior tibiotalar
Posterior tibiotalar
Plantar calcaneonavicular
Posterior talofibular
Calcaneofibular

Anterior talofibular
Long plantar
Spring ligament
Plantar
Deep transverse metatarsal
Collateral ligaments

Vascular Supply

Superficial Veins.

Dorsal venous arch (superficial fascia) drains medially into great saphenous vein which terminates into the femoral vein.
Dorsal venous arch drains laterally into small saphenous vein which terminates in popliteal vein.

Posterior Tibial A/V.

Terminate in medial and lateral plantar A/V, deep plantar arch, plantar metatarsal, and plantar digital branches.

Lateral plantar artery.
Medial plantar artery.
Posterior tibial artery.

Anterior Tibial A/V.

Terminate into dorsalis pedis A/V, arcuate artery, dorsal metatarsal and dorsal digital branches.

Anterior tibial artery.
Dorsalis pedis artery.

Innervation

Medial plantar nerve (branch of tibial nerve).
Lateral plantar nerve (branch of tibial nerve).
Ventral rami of S1, S2, S3.

Deep fibular nerve.

L4-S1. From sciatic nerve > common fibular > deep fibular/peroneal nerve. Terminal branch of the common fibular. Innervates anterior compartment and some intrinsic muscles of the foot.

Superficial fibular nerve.

L4-S1. Arises from common fibular and is the terminal branch. Innervates lateral compartment of the leg.

Tibial Nerve.

L4-S3. Branch of sciatic nerve and arises from the popliteal nerve. Major nerve of lower limb. Muscular innervation of posterior thigh and leg. Innervates posterior compartment of leg and most of intrinsic foot muscles. Passes through tarsal tunnel (via superior flexor retinaculum).

Common fibular nerve.

L4-S2. Directly innervates biceps femoris short head. Innervates lateral and anterior compartments of leg. Arises from sciatic nerve at the bifurcation.

Lateral plantar nerve.

Branch of the tibial nerve. Innervates skin of 5^th toe and lateral half of 4^th toe, and most deep muscles of the foot. Superficial branch–innervate the flexor digiti minimi brevis, the lumbrical muscles and the plantar skin of the fourth and fifth toes. Deep branch–innervates the adductor hallucis, opponens digiti minimi, quadratus plantae, plantar interossei and dorsal interossei muscles.

Medial plantar nerve.

Terminal branch of tibial nerve. Arises from flexor retinaculum and runs deep to abductor hallucis and alongside the plantar artery.

Sciatic, L4-S3.
Tibial branch, L4-S3.
Posterior compartment and plantar foot:
Common fibular, L4-S2.
Deep fibular.
Anterior compartment and dorsal foot:
Superficial fibular.
Lateral compartment:

*Four muscles innervated by the medial plantar nerve: ABD hallucis; flexor hallucis brevis; first lumbrical; flexor digitorum brevis.

*Lateral plantar nerve innervates all the rest.

Sole of foot.

Medial side = medial plantar nerve.
Lateral side = lateral plantar nerve.
Heel = tibial nerve.

Dorsum of foot.

Motor: deep fibular nerve.
Sensory: 3 S’s
Medial = saphenous
Central = superficial fibular

Clinical/Pathology

Pulse Points. The post-tibial arter is halfway between the heel and medial malleolus.

Foot Drop.

(Deep fibular/peroneal nerve).

Superficial Fibular Nerve Entrapment.

(Superficial fibular/peroneal nerve impingement/compression). Pain and paraethesia of lower leg and dorsum of foot.

Tarsal Tunnel Syndrome.

Tibial nerve.

Common Fibular Nerve.

Cast too tight. Fracture of fibula.

Medial Plantar Nerve Entrapment.

Pain caused in inner heal by entrapment/impingement of the nerve branches in all the small structures (e.g. ligaments etc.).

Other Features

Extensor Hoods/Expansions

Connective attachments where extensor tendons insert into the phalanges.

Tarsal Tunnel

Medial ankle.
Passage for posterior tibial a/v; tibial nerve; tibialis posterior, flexor digitorum longus, flexor hallucis longus tendons (Tom, Dick, Blood Nervous Hiding Harry) into sole.
Flexor retinaculum.
Posterior to medial malleolus, medial/posterior talus.
Medial calcaneus and inferior to sustentaculum tali.

Arches

Medial longitudinal arch: calcaneus, talus, navicular, cuneiforms, metatarsals 1-3. Higher of the longitudinal arches. Absorb distributes downward forces from standing and moving. *Elastic.

Lateral longitudinal arch: calcaneus, cuboid, metatarsals 4-5. “The arch”, most prominent. Flatter of the longitudinal arches. Touches ground when in standing position.

“Fundamental longitudinal arch is contributed to by both, and consists of the calcaneus, cuboid, third cuneiform, and third metatarsal: all the other bones of the foot may be removed without destroying this arch”. https://www.physio-pedia.com/Arches_of_the_Foot

Transverse arch: series of arches in the coronal plane. The highest is at the proximal head of talus.

See https://www.physio-pedia.com/images/6/6d/Arches_of_foot.jpg

Supporting Structures of the Arches

Plantar Aponeurosis

Tuberosity of 5th Metatarsal

Superior Extensor Retinaculum

Inferior Extensor Retinaculum

Detailed Studies

Notes

References

Biel, A. (2015). Trail guide to the body: A hands-on guide to locating muscles, bones and more.

Cedars-Sinai. (2018). Vertebrae of the spine. Retrieved from https://www.cedars-sinai.org/health-library/diseases-and-conditions/v/vertebrae-of-the-spine.html

Jenkins, G., & Tortora, G. J. (2012). Anatomy and Physiology: From Science to Life, 3rd Edition International Stu. John Wiley & Sons.

Muscolino, J. E. (2017). The muscular system manual: The skeletal muscles of the human body.