Q8-4. Dorsum of the Foot

Question 1

What dermatomes cover the dorsum of the foot?

Answer 1

S1 (lateral 1/3) and L5 (medial 2/3)

Question 2

What two muscle tendons travel deep to the superior extensor retinaculum and the stem of the inferior extensor retinaculum?

Answer 2

Extensor digitorum longus and Fibularis tertius

Question 3

What is the course of the cervical ligament?

Answer 3

Runs from the sulcus calcanei to the neck of the talus

Question 4

Which ligaments have attachments to the lateral portion of the sulcus calcanei (floor of the sinus tarsi)?

Answer 4

• Cervical ligament
• Bifurcate ligament
• Inferior extensor retinaculum (three attachment sites)
• Interosseous talocalcaneal ligament

Question 5

What muscles originate in the lateral portion of the floor of the sinus tarsi?

Answer 5

• Extensor digitorum brevis

- Extensor hallucis brevis

Question 6

What is the innervation of the extensor digitorum & hallucis brevis

Answer 6

Lateral terminal branch of deep fibular nerve

Question 7

What is the blood supply to the extensor digitorum & hallucis brevis?

Answer 7

Lateral tarsal artery

Question 8

What are the origins of extensor digitorum brevis?

Answer 8

• Floor of sinus tarsi
• Inferior extensor retinaculum
• Interosseous talocalcaneal ligament

Question 9

What tendons pass superficially to EDB muscle after it divides into 3 bellies?

Answer 9

Fibularis tertius and Extensor digitorum

Question 10

What are the insertions of the three bellies of EDB?

Answer 10

The three bellies give rise to tendons to the 2nd-4th digits (occasionally 5th digit, too). Each tendon fuses with its respective EDL tendon as it crosses the proximal phalanx. The tendons terminate on the intermediate and distal phalanges.

Question 11

What are the major actions of EDB?

Answer 11

Each tendon will dorsiflex its respective MPJ and (P/D)PJ

Question 12

What are the main origin of the Extensor Hallucis Brevis?

Answer 12

In common with EDB:

• Floor of sinus tarsi
• Inferior extensor retinaculum
• Interosseous talocalcaneal ligament

Question 13

What tendons pass superficially to the EHB muscle belly?

Answer 13

Fibularis tertius and Extensor digitorum

Question 14

What is the insertion for EHB?

Answer 14

As it approaches the MPJ 1, it passes deep to the EHL tendon and inserts onto the base of the PP

Question 15

What is the major action of the EHB?

Answer 15

Dorsiflexion of MPJ 1

Question 16

En route to its insertion, what muscle, nerve, and artery does the EHB tendon pass over?

Answer 16

• 1st dorsal interosseous
• Medial terminal branch of deep fibular
• Dorsalis pedis/1st dorsal MT artery

Question 17

What does the EHB tendon pass deep to after passing over the nerve/artery/muscle trio?

Answer 17

EHB tendon passes deep to the EHL tendon

** the two tendons do NOT fuse, they remain separate.

Question 18

What compartment of the leg does the superficial fibular nerve supply?

Answer 18

Lateral compartment

Question 19

When does the superficial fibular nerve become superficial?

Answer 19

@ inferior 1/3 leg

Question 20

What are the cutaneous branches of the superficial fibular nerve?

Answer 20

• Intermediate dorsal cutaneous N.

- Medial dorsal cutaneous N.

Question 21

What does the medial dorsal cutaneous N branch into once it enters the foot?

Answer 21

• Proper dorsal digital branch to the medial side of the hallux
• Common dorsal digital branch (to 2nd & 3rd digits)

Question 22

What is the difference between “proper” and “common”?

Answer 22

“Proper” means that the nerve is going to one specific digit.
“Common” means that it is going to more than one digit.

Question 23

What muscles does the lateral terminal branch of the deep fibular nerve innervate?

Answer 23

EDB and EHB

**sends a twig to the 2nd dorsal interosseous muscle (sensory only)

Question 24

What travels with the lateral terminal branch of the deep fibular nerve?

Answer 24

The 1st and/or 2nd lateral tarsal arteries

Question 25

What muscles does the medial terminal branch of the deep fibular nerve innervate?

Answer 25

Sometimes sends a twig to 1st dorsal interosseous muscle

Question 26

What travels with the medial terminal branch of the deep fibular nerve?

Answer 26

The nerve travels on the lateral side of the dorsalis pedis artery then with the 1st dorsal metatarsal artery and its branches.

Question 27

What happens when the medial terminal branch of the deep fibular nerve reaches the 1st intermetatarsal space?

Answer 27

It divides into 2 proper digital nerves (sensory to dorsal web space).

**Note: only sensory up to the proximal part of nail bed–> important to know for administering digital nerve blocks.

Question 28

What nerve provides sensory innervation to the skin between the 1st and 2nd digits?

Answer 28

Deep fibular nerve

Question 29

What nerve provides sensory innervation to the skin on the lateral side of the foot and the dorsum of the foot along the 5th met up to the base 5th digit?

Answer 29

Lateral dorsal cutaneous (sural nerve)

Question 30

What nerve provides sensory innervation to the skin on the 5th digit

Answer 30

Proper dorsal digital nerve to the lateral side of the 5th digit

Question 31

What nerve contributes to the sensory innervation of the medial side of the leg below the knee to area over the navicular in the foot?

Answer 31

Saphenous nerve

Question 32

What are the three branches of the anterior tibial artery as it crosses the ankle?

Answer 32

• Anterior lateral malleolar artery
• Anterior medial malleolar artery
• Dorsalis pedis

Question 33

What are the contributing arteries to the lateral malleolar network (anastomoses)?

Answer 33

• Perforating fibular
• Anterior lateral malleolar
• Posterior lateral malleolar
• Lateral calcaneal
• Lateral tarsal
• Lateral plantar

Question 34

What are the contributing arteries to the medial malleolar network (anastomoses)?

Answer 34

• Anterior medial malleolar
• Posterior medial malleolar
• Medial calcaneal
• Medial tarsal
• Medial plantar