LE Functional Neuroanatomy

Question 1

Tibialis Anterior

Answer 1

• Nerve = deep peroneal/fibular nerve
• Roots = L4-L5
• Function = ankle DF
• Damage — would cause weakness leading to foot drop or foot slap
• Compensation — high steppage gait (excessive hip or knee flexion to clear foot)

Question 2

Extensor Hallucis Longus

Answer 2

• Nerve = deep peroneal/fibular nerve
• Root = L5
• Function = great toe extension
• Damage — difficulty with toe clearance
• Compensation — increased DF (which could lead to anterior tib overuse pain / shin splints)

Question 3

Gastroc / Soleus / Plantaris

Answer 3

• Nerve = tibial nerve
• Root = S1-2
• Function = ankle PF
• Damage — difficulty with toe-off during gait and delayed heel off / increased DF (due to lack of PF)
• Compensation — reduced walking speed, decreased step length, and shorter stance phase

Question 4

Peroneus Longus and Brevis

Answer 4

• Nerve = superficial peroneal/fibular nerve
• Roots = L5-S1
• Function — foot eversion
• Damage — increased risk of inversion ankle sprains due to evertor weakness

Question 5

Posterior Tibialis

Answer 5

• Nerve = tibial nerve (because on post leg)
• Roots = L4-5
• Function = foot inversion (and assists PF)
• Damage — overpronation due to post tib weakness, contribute to pes planus (flat foot), and excessive medial rotation of tibia

Question 6

Quads (rectus femoris, vastus lateralis/medialis/intermedius)

Answer 6

• Nerve = femoral nerve
• Roots = L2-4 (L3 is big one because it does knee ext)
• Function = knee extension
• Damage — buckling of knee during stance phase
• Compensation — forward trunk lean or knee hyperextension (genu recurvatum)

Question 7

Hamstrings (biceps femoris, semitendinosus, semimembranosus)

Answer 7

• Nerve = sciatic nerve
• Roots = L5-S2
• Function = knee flexion and hip extension
• Damage — weakness causes difficulty with controlling terminal swing during gait and foot clearance
• Compensation — steppage gait to clear limb

Question 8

Glut Max

Answer 8

• Nerve = inferior gluteal nerve
• Roots = L5-S2
• Function =hip extension and ER
• Damage — weakness in this causes backward trunk lean (lurch gait) during early stance

Question 9

Iliopsoas

Answer 9

• Nerve = femoral (iliacus) and lumbar plexus (psoas)
• Roots = L1-3
• Function = hip flexion
• Damage — difficulty with swing phase initiation (clearing leg)
• Compensation — circumduction or contralateral vaulting

Question 10

Glut Med and Min

Answer 10

• Nerve = superior gluteal nerve
• Roots = L4-S1
• Function = hip abduction
• Damage — trendelenburg gait (or glut med gait) with lateral trunk lean towards side of weakness, and has contralat pelvic drop