Manual 90-92: Nerves of Leg

Question 1

longest branch of the femoral n.

Answer 1

saphenous n.

Question 2

course of the saphenous n.

Answer 2

• enters adductor canal with femoral a.
• crosses over a. from lateral to medial in the canal
• at the adductor hiatus, leaves canal y passing to the surface on the medial side of knee
• passes between tendons of sartorius and gracilis muscles
• runs with great saphenous v along medial side of leg

Question 3

does the saphenous n. pass through adductor hiatus

Answer 3

no

Question 4

in the proximal third of the leg, the saphenous n. divides into …

Answer 4

• a contribution to the subsartorial n. plexus

- infrapatellar branch, which provides cutaneous innervation to the skin over the patella

Question 5

in the distal third of the leg, the saphenous n. divides into its terminal branches …

Answer 5

• branches to the skin of the anterior and medial side of the leg and one that continues distally to end at the ankle
• a branch that continues to the medial side of the foot as far as the ball of the foot

Question 6

nerve root of tibial n.

Answer 6

anterior division of L4-S3

Question 7

describe the course of the tibial n.

Answer 7

• passes distally through the middle of the popliteal fossa crossing the popliteus m
• disappears between heads of gastrocnemius and deep to the soleus
• lies lateral to the popliteal a and v distally
• in popliteal fossa, crosses superficial to these vessels and leaves the popliteal fossa medial to them
• continues deep to soleus m. , eventually lying medial to the tendo calcaneus
• divides into medial and lateral plantar n. at the flexor retinaculum

Question 8

in the proximal leg, the tibial n. is ___________ to the posterior tibial a

Answer 8

medial

- just distal to the inferior border of the popliteus m it courses to the lateral side of the popliteal a.

Question 9

how many articular branches to the knee does the tibial n. supply

Answer 9

3

- corresponding to superior, inferior medial and middle genicular aa

Question 10

how many articular branches off tibial n. to ankle joint

Answer 10

1

Question 11

the branch off the tibial n. tot he flexor hallucis longus accompanies ..

Answer 11

fibular/peroneal a

Question 12

lies superficially in the groove between the heads of the gastrocnemius with the small saphenous v.

Answer 12

medial sural cutaneous n.

Question 13

what merges with the communicating ramus of the lateral sural cutaneous branch of the common fibular/peroneal n.

Answer 13

medial sural cutaneous n.

Question 14

communicating branch and medial sural cutaneous n =

Answer 14

sural n.

Question 15

describe the course of the sural n.

Answer 15

• continues distally supplying cutaneous branches to the skin of the posterior surface of the leg
• it also communicates with the posterior femoral cutaneous n
• enters foot by passing under the lateral malleolus and continues as the lateral dorsal cutaneous n .

Question 16

what are the last branches of the tibial n. in the leg

Answer 16

medial calcaneal nerves

- distributed to the skin of the heel and medial sole

Question 17

terminal branches of tibial n.

Answer 17

medial and lateral plantar n.

Question 18

second and smallest component of the sciatic n.

Answer 18

common fibular/peroneal n.

Question 19

what n. division compose the common fibular/peroneal n.

Answer 19

L4-S2

Question 20

describe the course of the common peroneal n.

Answer 20

• after is separates from the tibial n. it passes diagonally across the lateral portion of the popliteal fossa parallel to the medial border of the long head of the biceps femoris
• as it approaches the head of the fibula, it passes between the long head of the biceps femoris and the lateral head of the gastrocnemius
• after circling around the neck of the fibula, it passes deep to the fibularis/peroneus longus and divides into superficial and deep fibular branches

Question 21

before dividing into its terminal branches, the common fibular/peroneal n. gives rise to _______ articular branches to the knee

Answer 21

3

• one accompanies the superior lateral genicular a
• one accompanies the inferior lateral genicular a
• one accompanies the anterior tibial recurrent a through the tibialis anterior m to the knee joint

Question 22

what n. is distributed to the posterior and lateral surfaces of the knee

Answer 22

lateral sural cutaneous n

Question 23

what joins the medial sural cutaneous n to form the sural n. ?

Answer 23

communicating ramus of lateral sural cutaneous n.

Question 24

what arises deep to the fibularis/peroneus longus, passes inferiorly between the fibularis longus and extensor digitorum longus?

Answer 24

superficial fibular n.

• it gives rise to two dorsal cutaneous branches supplying the foot
• also has muscular branches to the fibularis longus and brevis

Question 25

what n. accompanies the anterior tibial a. from the proximal one third of the leg and passes with it deep to the extensor retinaculum?

Answer 25

deep fibular/peroneal n.

- divides into medial and lateral terminal branches distal to extensor retinaculum

Question 26

muscular branches of the deep peroneal n supply what muscles

Answer 26

tibialis anterior, extensor digitorum longus, peroneus tertius, extensor hallucis longus

Question 27

variations in the sural n. and their branches

Answer 27

• the sural branches may be lacking or may extend to the ankle
• the sural n. is formed by a union of the medial sural cutaneous and peroneal communicating branch in 80% of people
• in remaining 20%, the sural n originates from medial sural cutaneous n only