9-1. Lateral Compartment Overview

Question 1

other name for fibular?

other name for fibularis?

Answer 1

• fibular = peroneal
• fibularis = peroneus

Question 2

course of the common peroneal/ fibular nerve in the posterior leg?

Answer 2

heads anterolaterally

Question 3

the lateral compartment muscules are developmentally:

1. dorsal/ ventral, and preaxial/ postaxial?
2. innervation?
3. action?

Answer 3

• dorsal, postaxial muscles
• innervated by composed of posterior division fibers
• act: major foot evertors

Question 4

course of the lateral compartment muscles

Answer 4

• They travel posterior to the lateral malleolar sulcus
  
  • fibularis longus more superficially

Question 5

relationship between fibularis longus and fibularis brevis in the lateral compartment?

Answer 5

• Reaching the lateral side of the calcaneus, f. brevis travels above and f. longus travels below the peroneal/fibular trochlea/tubercle
• Fibularis brevis and fibularis longus share a common synovial sheath up to the peroneal trochlea

Question 6

If an os vesailanum is present, where will it be?

Answer 6

• this is an accessory ossice
• would be invested in the fibularis brevis

Question 7

After fibularis longus travels below the peroneal/fibular trochlea/tubercle, what is it’s path?

Answer 7

• F. longus will make its way to the lateral side of the cuboid where it travels through the peroneal notch, envelop its sesamoid (os peroneum)
• Then travelS in close proximity to the peroneal sulcus

Question 8

On rare occasions close to the insertion sites of the fibularis longus, there may be an accessory bone called what?

Answer 8

pars peronea metatarsalis primi

Question 9

2 muscles of the lateral compartment

Answer 9

• fibularis longus
• fibularis brevis

Question 10

which muscle belly fills most of superior half of lateral compartment becoming tendinous as it passes inferiorly?

Answer 10

Fibularis/ peroneus longus

(then runs superficially to Fibularis brevis down the leg)

Question 11

Fibularis/ peroneus longus

1. origin
2. insertion
3. innervation
4. main action

Answer 11

1. o: head and sup. 2/3 of lateral surface of fibula
2. ins: base of 1st MT and medial cuneiform
3. inn: superficial fibular nerve (L5, S1, S2)
4. act: everts foot and weekly plantarflexes ankle

Question 12

Fibularis/ peroneus brevis

1. origin
2. insertion
3. innervation
4. main action

Answer 12

1. o:
   
   • inferior 2/3 of lateral surface of fibula
2. ins:
   
   • dorsal 2/3 of lateral surface of fibula
3. inn:
   
   • superficial fibular nerve (L5, S1, S2)
4. act:
   
   • everts foot and weekly plantarflexes ankle

Question 13

what is the common innervation of the lateral compartment?

Answer 13

superficial fibular nerve (L5, S1, S2)

Question 14

which muscle belly fills the inferior half of lateral compartment?

Answer 14

fibularis/ peroneus brevis

Question 15

In rare cases, what can happen with the fibularis longus and fibularis brevis tendons?

Answer 15

in rare occasions, the tendons can be fused

Question 16

Do not confuse the fibularis brevis insertion site w/ that of the Fibularis tertius. Where does F. tertius insert?

Answer 16

• F tertius inserts on the dorsum of the MT 5 base or proximal shaft
• F brevis inserts on base of MT1 and medial cuneiform

Question 17

Where else can the fibularis brevis send a slip?

Answer 17

distally to the 5th toe directly, or by joining the EDLT (extensor digitorum longus tendon)

Question 18

which muscle is palpable from the fibular head to the lateral malleolus?

Answer 18

fibularis/ peroneus longus is palpable throughout most of its course in the leg

Question 19

INVERSION or EVERSION:

which contributes to foot pronation?

which muscles are involved?

Answer 19

• EVERSION contributes to foot PRONATION
• Muscles used are the accessory ankle plantarflexors

Question 20

what is the mnemonic:

remember, out of all the meninges, the PIAS DEEP

Answer 20

• PIAS
  
  • Plantarflexion
  • Inversion
  • ADduction
  • Supination
• DEAP
  
  • Dorsiflexion
  • Eversion
  • ABduction
  • Pronation

Question 21

During supination, which bones:

1. INVERT
2. PLANTARFLEX/ dorsiflex
3. ADDUCT/ abduct

Answer 21

During supination,

1. Inversion: calcaneus
2. Plantarflex: calcaneus,navicular, cuboid
   
   • Dorsiflex: talus
3. ADduct: calcaneus, navicular, cuboid
   
   • Abduct: talus

Question 22

during pronation, the following bones move during:

1. EVERSION
2. DORSIFLEXION, plantarflexion
3. ABDUCTION, adduction

Answer 22

1. EVERSION - calcaneus
2. DORSIFLEXION - calcaneus, navicular, cuboid
   
   • plantarflexion - talus
3. ABDUCTION - calcaneus, navicular, cuboid
   
   • adduction - talus

Question 23

what are the steps between the foot becoming a (1) mobile pronating adaptor –> (2) stiff lever for propulsion?

Answer 23

*Prior to becoming pronating adaptor, foot enters STANCE PHASE in a SUPINATED position

1. mobile, pronating adaptor

As foot lowers to ground for FOOT FLAT, PRONATION occurs and continues into midstance

2. stiff lever for propulsion

Late midstance to toe-off, the foot SUPINATES/ STIFF EVER

Question 24

what is the basic 3 step summary of stance phase?

Answer 24

Question 25

what is the function of the lateral compartment muscles during gait?

Answer 25

* Both lateral compartment muscles are **active PRIOR to initial contact** * Prepares the foot for weight acceptance * Prevents excessive inversion at heel strike

Question 26

what is the function of the FIBULARIS LONGUS ONLY during gait?

Answer 26

* **Heel Strike to Foot Flat:** * aids in the pronation necessary for foot to accommodate substrate * **Midstance**: * plantarflexes the first ray providing stability to this digit as weight is transferred to the forefoot

Question 27

**lateral muscular compartment:** innervation and blood supply

Answer 27

* inn: **superficial fibular nerve** * artery: from the **anterior tibial** and **fibular arteries**

Question 28

how often is the **peroneus quartus** present?

Answer 28

* up to ~20% of study samples * various names, origin, and insertion * \*unique to humans

Question 29

**peroneus quartus:** potential origins, potential insertions

Answer 29

* Potential Origins: * lateral surface of the fibula below or above the origin of fibularis brevis, * posterior intermuscular septum, or * directly from either the fibularis brevis or longus muscle bellies * Potential Insertions: * retrotrochlear eminence, * peroneal tubercle, * inferior peroneal retinaculum, * cuboid, and * fibularis longus or brevis tendons

Question 30

what structure(s) needs to be protected while finding where the deep fibular and superficial fibular nerves split? what may need to be cut?

Answer 30

* may need to cut thru 1-2 muscles (fibularis longus, and extensor digitorum longus) * when making the incision, protect the **common fibular and its branches**

Question 31

what is usually the last branch off of the common fibular nerve before it terminates into superficial and deep fibular nerves? what is it's course?

Answer 31

* **recurrent articular nerve branch** is usually the last branch * runs w/ the anterior tibial recurrent artery * pierces the tibialis anterir muscle