Anterolateral Leg

Question 1

What does fascia do?

Answer 1

Cover the leg muscles

Question 2

Describe how the fascia transitions as you move inferiorly down the lower extremity

Answer 2

Fascia lata in the thigh becomes the crural fascia in the leg which thickens around the ankle to form the superior and inferior extensor retinaculum

Question 3

What are the 4 important septum that separate compartments in the leg?

Answer 3

Transverse septum, posterior septum, anterior septum, interosseus membrane

Question 4

What does the interosseus membrane separate?

Answer 4

The anterior compartment and the posterior deep compartment

Question 5

What does the transverse septum separate?

Answer 5

The posterior deep and posterior superficial compartments

Question 6

What does the anterior septum separate?

Answer 6

The anterior and lateral compartments

Question 7

What does the posterior compartment separate?

Answer 7

The lateral and posterior superficial compartments

Question 8

What are the 4 muscles in the anterior leg?

Answer 8

Tibialis Anterior, Extensor hallucis longus, extensor digitorum longus, fibularis tertius

Question 9

Origin, insertion, action and innervation of Tibialis Anterior

Answer 9

O: Lateral tibial condyle and superolateral 1/2 of tibia
I: Medial side of medial cuneiform and base of 1st metatarsal
Action: Dorsiflexion and inversion of the foot
Innervation: Deep fibular nerve

Question 10

Origin, insertion, action and innervation of Extensor digitorum longus

Answer 10

O: Lateral tibial condyle, interosseus membrane and anterior fibular surface
I: Dorsum of 2nd-5th middle and distal phalanages
Action: Dorsiflexion and extension of 2-5 phalanges
Innervation: Deep fibular nerve

Question 11

Explain the extensor expansion function of the extensor digitorum longus tendon

Answer 11

As the tendon attaches, it attaches to the middle and distal joints of the toes and provides a covering for them. At the proximal IP joint, it has one medial slip and at the distal IP joint it splits into 2 lateral slips

Question 12

Origin, insertion, action and innervation of Extensor hallucis longus

Answer 12

O: Anteromedial fibular surface and interosseous membrane
I: Dorsum of base of 1st distal phalanx
Action: Dorsiflexion and extension of hallux
Innervation: Deep fibular nerve

Question 13

Origin, insertion, action, and innervation of Fibularis Tertius

Answer 13

O: Anteroinferior aspect of fibular and interosseus membrane
I: Base of 5th metatarsal
Action: Dorsiflexion and eversion of the foot (lateral movement)
Innervation: Deep fibular nerve

Question 14

Where is Fibularis Tertius in respect to the other fibularis muscles?

Answer 14

Anterior to fibula!

Question 15

What is the nerve that innervates all of the anterior leg muscles?

Answer 15

Deep fibular nerve

Question 16

Explain how the deep fibular nerve arises

Answer 16

Sciatic splits into tibial nerve and common fibular nerve, the common fibular nerve then runs anteriorly and splits into the deep fibular nerve and the superficial fibular nerve

Question 17

Where does the deep fibular nerve run?

Answer 17

In between tibialis anterior and extensor hallucis longus

Question 18

What all does the deep fibular nerve supply?

Answer 18

Anterior leg muscles, skin between the 1st and 2nd toe, ankle joint, dorsal foot muscles

Question 19

What is the main arterial source for the anterior leg muscles?

Answer 19

Anterior tibial artery

Question 20

What does the anterior artery become inferiorly?

Answer 20

Dorsalis Pedis at the malleoli

Question 21

What are the lateral leg muscles?

Answer 21

Fibularis longus and fibularis brevis

Question 22

What nerve innervates the lateral leg muscles?

Answer 22

Superficial fibular nerve

Question 23

Origin, insertion, action, innervation of fibularis longus

Answer 23

O: Head of fibula and upper 2/3 of fibula
I: Medial cuneiform and 1st metatarsal (runs across dorsal foot via cuboid sulcus)
Action: Eversion of foot and plantar flexion
Innervation: Superficial fibular nerve

Question 24

Origin, insertion, action, innervation of fibularis brevis

Answer 24

O: inferolateral fibula
I: 5th metatarsal base tuberosity
Innervation: superficial fibular nerve
Action: Eversion of foot and plantarflexion

Question 25

What does the superficial fibular nerve supply?

Answer 25

Lateral leg muscles, cutaneous innervation of anteroinferior leg and almost entire dorsum of foot

Question 26

What is the most commonly injured LE nerve?

Answer 26

Common fibular nerve

Question 27

What results if the common fibular nerve is injured?

Answer 27

Paralysis of ALL anterior and lateral leg muscles!

Question 28

How will a patient present if they have an injured common fibular nerve?

Answer 28

“Foot drop” with loss of dorsiflexion and eversion
Difficult to achieve heel strike, usually have some sort of stepping, waddling, or swing out gait
Foot will strike with “clop”
Loss of sensation of anterolateral leg and dorsum of foot

Question 29

What is the one compartment that does not have its own artery that runs with the nerve?

Answer 29

LATERAL COMPARTMENT has NO distinct artery!

Question 30

How does the lateral compartment of the leg receive blood?

Answer 30

The popliteus becomes the posterior tibial artery which then sends off a fibular artery branch that has perforating arteries that run anteriorly to lateral compartment

Question 31

How may compartment syndrome arise?

Answer 31

Trauma of the leg may lead to hemorrage, edema, and inflammation within the fascia of the LE which causes an increase in pressure within the muscle compartment

Question 32

What does the increase in pressure of compartment syndrome cause?

Answer 32

Ischemia - low oxygen delivery to the muscles

Question 33

How do you fix compartmental syndrome?

Answer 33

Fasciotomy to relieve the pressure

Question 34

What is a mild form of compartmental syndrome?

Answer 34

Shin splints (swelling of anterior tibialis)

Question 35

What do shin splits hurt?

Answer 35

Repetitive microtrauma to the anterior tibialis and small tears to the overlying fascia