Gross Anatomy-Muscles of Lateral Compartment

Question 1

Describe the **Muscles of Lateral Compartment **

Answer 1

• Smallest leg compartment
• Contains 2 muscles

Question 2

What 2 muscles do the Lateral Compartment contain?

Answer 2

Fibularis Longus (FL)

Fibularis Brevis (FB)

Question 3

Describe the Fibularis Longus (FL)

Answer 3

• Longer and more superficial of the two
• Tendon can be observed proximal and posterior to lateral malleolus
• Tendon passes inferior to fibular trochlea
• Crosses sole of foot obliquely
• *O:** Head and superior 2/3 lateral surface of fibula
• *I:** Base of 1st metatarsal and medial cuneiform
• *A:** Eversion and weak plantarflexion
• *N:** Superficial fibular n. (L5, S1, S2)
• *B**: Perforating branches of fibular and anterior tibial aa.

• Helps steady leg on foot when standing

• Depresses medial margin of foot

• Acts on subtalar and transverse tarsal joints for eversion

Question 4

Describe the Fibularis Brevis (FB)

Answer 4

• Fusiform m.
• Lies deep and is shorter than FL
• Tendon can be palpated inferior to it
O: Inferior 2/3 of lateral surface of fibula
I: Dorsal surface of tuberosity on lateral side of base of 5th metatarsal
A: Eversion and weak plantarflexion
N: Superficial fibular n. (L5, S1, S2)
B: Perforating branches of fibular and anterior tibial aa.

Question 5

how do you test for FL & FB

Answer 5

• To test FL and FB:

• Evert foot against resistance
• Normally, tendons can be seen and palpated inferior to lateral malleolus
• Tests integrity of superficial fibular n.

Question 6

Describe the Vasculature of Lateral Compartment

Answer 6

• No artery courses through lateral compartment
• Supplied by:
• Perforating branches from anterior tibial a.
• Perforating branches from fibular a.

Question 7

Describe the Innervation of Lateral Compartment

Answer 7

• Superficial fibular n. – terminal branch of common fibular n.

• Only nerve in lateral compartment
• Terminates as:
  
  • Medial dorsal cutaneous n.
  • Intermediate dorsal cutaneous n.

• Lateral sural cutaneous n. – from common fibular n.

• Supplies skin of upper lateral leg

Question 8

Describe a Fracture of 5th Metatarsal

Answer 8

• Caused by sudden violent inversion of ankle
• Causes fibularis brevis m. to fracture or avulse 5th metatarsal
• Common in tennis or basketball players
• Pain and edema around base of 5th metatarsal
• Often misdiagnosed as ankle inversion sprain

Question 9

Describe a Injury to Superficial Fibular n.

Answer 9

• Chronic ankle sprains may stretch this nerve
• Causes pain along lateral side of leg and dorsum of foot
• High lesion would cause:
• Weakened eversion
  
  • Foot would invert with dorsiflexion
• Sensory loss over anterolateral leg and dorsum of foot

well I would say week ankles :P