Q8-1a. Anterior Compartment Conference

Question 1

list the three borders of the tibia,

which are palpable

Answer 1

• anterior border (palpable)
• interosseous/lateral border
• medial border (palpable)

Question 2

The anterior osteofascial compartment is found between what two borders of the tibia?

Answer 2

Anterior & Interosseous/Lateral Borders

Question 3

You make an anterior incision parallel to the anterior border of the tibia.

Which dermatome did you cut?

Answer 3

L4/L5 dermatome

Question 4

which nerve supply the L5 dermatome?

Answer 4

• lateral sural cutaneous nerve;
• & superficial fibular

Question 5

which nerve supply the L4 dermatome?

Answer 5

saphenous nerve

Question 6

with an anterior incision parallel to the anterior border of the tibia (about 1 cm lateral to anterior border) –>

by widening the incision MEDIALLY, which structures will be running through the superficial fascia?

Answer 6

• great saphenous vein
• saphenous nerve

Question 7

with an anterior incision parallel to the anterior border of the tibia (about 1 cm lateral to anterior border) –>

by widening the incision LATERALLY, which structures will be running through the superficial fascia?

Answer 7

crural fascia overlying tibialis anterior

Question 8

anterior osteofascial compartment:

contents

Answer 8

• muscles
  
  • tibialis anterior
  • EHL (extensor hallucis longus)
  • EDL (extensor digitorum longus)
  • Fibularis tertius
• anterior tibial artery & veins
• deep fibular nerve

Question 9

motor innervation to muscles of anterior compartment

Answer 9

deep fibular nerve

Question 10

main blood supply to muscles of anterior compartment?

Answer 10

anterior tibial artery

Question 11

common function of muscles of anterior compartment

Answer 11

ankle dorsiflexion

Question 12

when are the anterior compartment muscles ESPECIALLY active during the gait cycle?

Answer 12

1. HEEL CONTACT/heel strike/initial contact
   
   • decelerate the foot so it touches down on the ground in a controlled manner
2. SWING PHASE
   
   • keeps the foot from dragging on the ground

Question 13

tibialis anterior: main origins

Answer 13

• Crural fascia
• Interosseous membrane
• Lateral tibial condyle
• Superior half of lateral surface of tibia

Question 14

tibialis anterior: insertion

Answer 14

•Medial-plantar surfaces of both the medial cuneiform & MT 1 base

Question 15

tibialis anterior: major actions

Answer 15

dorsiflexes the ankle;

inverts the foot

Question 16

what retinacula does the Tibialis anterior and EHL muscles pass deep to?

Answer 16

• superior extensor and
• inferior extensor

(both arms)

Question 17

Extensor hallucis longus:

main origins and insertion

Answer 17

• origins
  
  • •Middle part of anterior/medial surface of fibula

•Interosseous membrane

• insertion
  
  • Base of Distal phalanx of the hallux

Question 18

Extensor hallucis longus:

major actions

Answer 18

• Dorsiflexes ankle
• Dorsiflexes hallucal MTPJ and IPJ

Question 19

Extensor hallucis longus contributes to the formation of what structure that covers the dorsum of the hallux?

Answer 19

Extensor expansion

Question 20

What is the role of the extensor expansion?

Answer 20

It anchors the EHL tendon in place

Question 21

What is the name of the medial tendinous slip originating from the EHL (or less frequently, the TA or EHB) that inserts onto the dorsomedial aspect of the first MTPJ?

Answer 21

Extensor hallucis capsularis

Question 22

What is thought to be the function of the extensor hallucis capsularis?

Answer 22

retract the MTPJ capsule to prevent its impingement during MTPJ dorsiflexion

Question 23

The extensor hallucis capsularis is variable in size. If it’s larger, what may it be mistaken for?

Answer 23

EHL

Question 24

extensor digitorum longus:

main origins and insertion

Answer 24

Origins

• Crural fascia
• Anterior crural intermuscular septum
• Interosseous membrane
• Lateral condyle of tibia
• Head & superior 3/4s of anterior/medial surface of fibula

Insertion: Middle & distal phalanges of Digits 2-5

Question 25

extensor digitorum longus: major actions

Answer 25

* Dorsiflexes ankle * Dorsiflexes MTPJS and IPJS of digits 2-5 * Everts foot (secondary)

Question 26

what retinacula does the EDL and fibularis tertius pass deep to?

Answer 26

**stem** of superior extensor and inferior extensor

Question 27

At the level of the ankle, the extensor digitorum longus divides into how many tendons?

Answer 27

4 tendons

Question 28

What are the functions of the extensor expansions formed in part by the EDL tendons?

Answer 28

* Allows the EDL to extend the proximal phalanx to which this tendon has no attachment * Controls actions of the interossei & lumbrical muscles

Question 29

what are the 2 parts of the extensor expansion?

Answer 29

extensor sling extensor wing/hood

Question 30

what is the path of the EDB and EDL digital insertions (dorsal view)

Answer 30

* As EDB tendon crosses PP, joined by EDL tendon * At PP head, combined tendons trifurcate into 1 middle & 1 lateral and medial slip * Middle Slip attaches to IP * Medial and Lateral Slips reunite & attach at DP

Question 31

fibularis tertius: main origins and insertion

Answer 31

MAIN ORIGIN(S)? * Anterior crural interosseous septum * Interosseous membrane * Inferior 1/3 of anterior/medial surface of fibula * Usually fused with EDL INSERTION? Usually on dorsum of base/prox. shaft of MT 5 Can also attach to proximal end of MT 4 shaft

Question 32

fibularis tertius: main actions

Answer 32

* Dorsiflexes ankle (accessory role) * Everts foot (accessory role)

Question 33

anterior tibial artery: origin and termination

Answer 33

Origin: One of two terminal branches off popliteal artery @ soleal line Termination: After crossing the ankle, it continues as the Dorsalis Pedis/Dorsal Artery of the Foot

Question 34

what are the superior branches of the: anterior tibial artery?

Answer 34

* popliteal artery * posterior tibial recurrent artery * anterior tibial recurrent artery

Question 35

what are the 3 inferior branches of the: anterior tibial artery?

Answer 35

* dorsalis pedis * anterior lateral malleolar artery * anterior medial malleolar artery

Question 36

deep fibular/ peroneal nerve: origin and termination

Answer 36

Origin: * One of the terminal branches of the Common Fibular/Peroneal Nerve Termination: * Lateral & Medial Terminal Branches

Question 37

course of deep fibular/ peroneal nerve in anterior compartment

Answer 37

* originates in/or just before the fibular tunnel between fibularis/ peroneus longus & neck of fibula * passes thru the anterior intermuscular septum to enter anterior compartment and as it courses medially to the EDL, it meets up w/ the anterior tibial vessels * then it follows same course described for anteior tibial artery

Question 38

After passing through the interosseous membrane, the anterior tibial artery travels deep to and between which two muscles?

Answer 38

* descends between the tibialis anterior & extensor digitorum longus muscles

Question 39

just proximal to the talocrural joint, it is crossed by which tendon?

Answer 39

EHL tendon

Question 40

In its final portion, the **anterior tibial artery** lies deep to the superior extensor retinaculum and between which two tendons?

Answer 40

continues as the dorsalis pedis artery onto the dorsum of the foot lateral to the tendon **of the extensor hallucis longus** and medial to the **extensor digitorum longus** and deep peroneal nerve