Plantar Foot

Question 1

Describe the skin on the plantar foot

Answer 1

The skin on the sole of the foot is very thick (especially at weight-bearing points like the heel, lateral margin, and base of the hallux)

Question 2

Describe the superficial fascia on the plantar foot

Answer 2

The superficial fascia has fibrous septa dividing the tissue into fat-filled areas for shock absorption (the calcaneal fat pad is especially prominent); the fibrous septa also anchor the skin to the deep fascia (improves grip)

Question 3

Describe the deep fascia of the sole

Answer 3

The deep fascia of the sole is called the plantar fascia

• The thickened central portion is called the plantar aponeurosis
• Functions: protection, maintaining the arches of the foot

Question 4

What is plantar fasciitis?

Answer 4

-Inflammation of the plantar aponeurosis (plantar fasciitis) presents as pain on the plantar surface of the heel and medial aspect of foot; it can induce ossification in the posterior attachment of the aponeurosis, forming a calcaneal spur; a bursa may develop at the spur and this may also become inflamed

Question 5

What in included in the 4 Layers of the Plantar Foot?

Answer 5

1) Layer 1 (superficial)
- Abductor hallucis
- Abductor digiti minimi
- Flexor digitorum brevis

2) Layer 2
- Tendon of flexor hallucis longus
- Tendon of flexor digitorum longus
- Quadratus plantae
- Lumbricals

3) Layer 3
- Flexor hallucis brevis
- Adductor hallucis (transverse & oblique heads)
- Flexor digiti minimi brevis

4) Layer 4 (deep)
- Interossei
- 3 Plantar Interossei
- 4 Dorsal Interossei

Question 6

Describe portions of the Layer 1 (superficial) in terms of their actions and insertions

Answer 6

1) Abductor hallucis
- Actions: abduct and flex hallux (MTP joint)

2) Abductor digiti minimi
- Actions: abduct and flex digit 5 (MTP joint)

3) Flexor digitorum brevis
- Insertion: 4 tendons; divide to insert on middle phalanges of digits 2-5
- Action: flex digits 2-5 (MTP & PIP joints)

Question 7

Describe the Tendon of flexor hallucis longus

Answer 7

• Emerges from tarsal tunnel, courses deep to FDL tendon and along the medial side of the plantar foot.
• Sends tendinous slip(s) to the tendon of FDL.
• Travels between the two sesamoids of the hallux, to insert on the distal phalanx.
• Flexes the MTP & IP joints of the hallux.

Note: flexor hallucis longus is innervated by the tibial nerve in the posterior compartment of the leg

Question 8

Describe the Tendon of flexor digitorum longus

Answer 8

• Emerges from tarsal tunnel, crosses superficial to FHL tendon and splits into 4 tendons (to digits 2-5).
• Each tendon passes through the divided tendon of flexor digitorum brevis to insert on the distal phalanx.
• Flexes the MTP, PIP & DIP joints of digits 2-5.

Note: flexor digitorum longus is innervated by the tibial nerve in the posterior compartment of the leg

Question 9

Describe Quadratus plantae (action) and Lumbricals (origin, insertion, and actions)

Answer 9

Quadratus plantae
-Action: assist flexor digitorum longus in flexing digits 2-5 (MTP, PIP & DIP joints)

Lumbricals

• Origin: tendons of flexor digitorum longus
• Insertion: extensor expansions of digits 2-5
• Actions: flex MTP joints; extend PIP & DIP joints of digits 2-5

Question 10

Describe the insertions and actions of the Flexor hallucis brevis

Answer 10

• Insertion: two tendons* insert on proximal phalanx of hallux
• Action: flex hallux (MTP joint)

*Each tendon (medial & lateral) has a sesamoid embedded in it. These sesamoids provide added leverage, help hold the tendon of FHL in place, & protect the tendon of FHL from being compressed during toe-off

Question 11

What are the actions of Adductor hallucis and Flexor digiti minimi brevis?

Answer 11

Adductor hallucis (transverse & oblique heads)
-Action: adduct hallux (MTP joint) 

Flexor digiti minimi brevis
-Action: flex digit 5 (MTP joint)

Question 12

Describe the portions of Interossei and their respective actions.

Answer 12

3 Plantar Interossei
-Action: adduct MTP joints of digits 3-5
(“PAD” = Plantar Interossei Adduct)

4 Dorsal Interossei
-Action: abduct MTP joints of digits 2-4
(“DAB” = Dorsal Interossei Abduct)

Question 13

what are the Nerves of the Plantar Foot?

Answer 13

1) Tibial nerve divides into lateral and medial plantar nerves as it enters the sole
2) Lateral plantar nerve (S2-3)
3) Medial plantar nerve (S2-3)

Question 14

Describe motor and sensory of the Lateral plantar nerve (S2-3)

Answer 14

• Motor: abductor digiti minimi, flexor digiti minimi brevis, quadratus plantae, adductor hallucis, lateral 3 lumbricals (2nd-4th), all interossei
• Sensory: lateral aspect of sole & tips and plantar aspects of lateral 1½ digits

Question 15

Describe motor and sensory of the Medial plantar nerve (S2-3)

Answer 15

• Motor: abductor hallucis, flexor hallucis brevis, medial (1st) lumbrical, and flexor digitorum brevis
• Sensory: medial aspect of sole & tips and plantar aspects of medial 3½ digits

Question 16

Describe the Arteries of the Plantar Foot

Answer 16

Posterior tibial artery divides into 1) medial and 2) lateral plantar arteries in the sole (branches anastomose with one another)

Question 17

Describe the Medial plantar artery

Answer 17

• Travels with the medial plantar nerve
• Supplies superficial tissues of the sole and the muscles associated with the hallux
• Gives rise to the superficial plantar arch (superficial to flexor digitorum brevis)
• Gives rise to plantar digital arteries to the hallux and medial side of digit 2 (anastomose with branches from the lateral plantar artery)

Question 18

Describe the Lateral plantar artery

Answer 18

• Travels with the lateral plantar nerve
• Supplies most of the plantar foot
• Gives rise to the deep plantar arch (between 3rd & 4th plantar layers)
• Deep plantar arch gives rise to plantar metatarsal arteries
• Plantar metatarsal arteries give rise to plantar digital arteries to the medial and lateral aspects of the digits (anastomose with branches from the medial plantar artery)

Question 19

Describe the Veins of the Plantar Foot

Answer 19

• Deep veins accompany the arteries and share the same names (e.g., plantar digital veins) and drain into the fibular and posterior tibial veins
• Superficial veins drain into the small saphenous and great saphenous veins