Tables 14-17 provide details of the muscles of the lower leg, and figure 87a–h illustrates the bones and muscle. Figure 88a,b shows anteroposterior and lateral radiographs of the normal knee and figure 88c,d shows the details that can be obtained of bone and soft tissue with MRI images; they are particularly valuable in identifying abnormalities of the menisci and cruciate ligaments.

Table 14 Muscles of the anterior (extensor) compartment of the leg

Table 15 Muscles of the lateral (peroneal/fibular) compartment of the leg

Table 16 Superficial Muscles of the posterior ( flexor) compartment of the leg

Table 17 Deep muscles of the posterior (flexor) compartment of the leg

Figure 87
a. Bones of right lower leg: anterior

1. Semimembranosus
2. Iliotibial tract
3. Lateral collateral ligament, passing to head of fibula
4. Biceps tendon: attached around collateral ligament
5. Patellar tendon
6. Sartorius
7. Gracilis
8. Peroneus longus
9. Semitendinosus
10. Extensor digitorum longus
11. Tibialis anterior: to medial cuneiform and first metatarsal
13. Peroneus brevis: to styloid process of fifth metatarsal
14. Peroneus tertius
15. Medial malleolus
16. Talus
17. Lateral malleolus
18. Tibialis posterior

Figure 87
b. Muscles of right lower leg: anterior

1. Quadriceps tendon
2. Vastus medialis
3. Vastus lateralis
4. Iliotibial tract
5. Patellar tendon
6. Sartorius
7. Tibialis anterior
8. Gastrocnemius
9. Peroneus longus
10. Extensor digitorum longus: passing to distal phalanx
11. Soleus
12. Perforating peroneal artery: palpate on lateral maleolus
13. Dorsalis pedis artery: palpated lateral to flexor hallucis tendon, on metatarsal
14. Extensor hallucis longus

Figure 87
c. Bones of right lower leg: posterior

1. Semimembranosus
2. Popliteus
3. Soleus
4. Tibialis posterior
5. Flexor hallucis longus
6. Flexor digitorum longus
7. Peroneus brevis
8. Medial malleolus
9. Lateral malleolus
10. Talus
11. Tendo Achilles (tendocalcaneus)
12. Calcaneus

Figure 87
d. Muscles of right lower leg: posterior

1. Vastus lateralis
2. Biceps
3. Gracilis
4. Semitendinosus
5. Semimembranosus: on either side
of semitendinosus
6. Low division of sciatic nerve
7. Popliteal artery
8. Poplietal vein (divided)
9. Medial head of gastrocnemius
10. Lateral head of gastrocnemius
11. Peroneus longus and brevis
12. Soleus; bulging on either side of gastrocnemius
13. Extensor retinaculum
14. Tendo Achilles (tendocalcaneus)

Figure 87
e. Bones of right lower leg: lateral

1. Biceps
2. Extensor digitorum longus
3. Patellar tendon
4. Soleus
5. Peroneus longus
6. Tibialis anterior
7. Flexor hallucis longus
8. Peroneus brevis
9. Peroneus tertius
10. Lateral maleolus
11. Talus
12. Cuboid
13. Calcaneus
14. Extensor hallucis longus

Figure 87
f. Muscles of right lower leg: lateral


1. Rectus femoris
2. Iliotibial tract
3. Biceps femoris
4. Vastus lateralis
5. Quadriceps tendon
6. Patellar tendon
7. Gastrocnemius, lateral head
8. Common peroneal nerve
9. Soleus
10. Muscles of anterior compartment
11. Peroneus longus
12. Dotted lines: upper and lower extensor retinaculi
13. Extensor digitorum longus tendons
14. Tendo Achilles (tendocalcaneus)
15. Expanded tendon of peroneus tertius
16. Peroneus brevis

Figure 87
g. Bones of right lower leg: medial


1. Gastrocnemius
2. Femoral attachment of medial collateral ligament
3. Semimembranosus
4. Popliteus
5. Patellar tendon
6. Gracilis
7. Sartorius
8. Semitendinosus
9. Medial maleolus
10. Talus
11. Tibialis posterior: to navicular tuberosity
12. Calcaneus
13. Tendo Achilles (tendocalcaneus)
14. Tibialis anterior: to medial cuneiform and first metatarsal
15. Extensor hallucis longus

Figure 87
h. Muscles of right lower leg: medial


1. Semimembranosus
2. Sartorius
3. Semitendinosus
4. Gracilis
5. Quadriceps tendon
6. Vastus medialis
7. Patellar tendon
8. Medial head of gastrocnemius 9. Tibialis anterior
10. Soleus
11. Flexor digitorum longus
12. Medial malleolus
13. Tendo Achilles (tendocalcaneus) 14. Tibialis posterior
15. Posterior tibial artery
16. Flexor retinaculum: passing from the calcaneus
17. Abductor hallucis

The neutral position of the knee is in extension and a painful knee is often held in a few degrees of flexion. Compare the two sides. Note skin changes, swellings, deformity, and other changes of contour (figure 89a,b). Pre- and infrapatellar bursae, popliteal cysts and cartilaginous protrusions along the joint line are common pathologies. Quadriceps wasting is most easily seen by hollows on either side of, and just above, the patella (particularly medially, due to loss of bulk of the lower fibres of the vastus medialis muscle). General or local muscle wasting is assessed by measurement of leg circumference and comparing with the opposite side (page 349).

Figure 89
a. Surface anatomy of medial aspect of right knee.

1. Rectus femoris
2. Quadriceps tendon
3. Patella
4. Vastus medialis
5. Sartorius
6. Medial condyle of femur
7. Gracilis
8. Medial meniscus
9. Medial collateral ligament
10. Patellar tendon
11. Semimembranosus: deep to and on either side of 12
12. Semitendinosus
13. Medial condyle of tibia
14. Gastrocnemius
15. Soleus
16. Muscles of anterior compartment of leg

Figure 89
b. Surface anatomy of lateral aspect of right knee.


1. Quadriceps tendon
2. Rectus femoris
3. Patella
4. Lateral femoral condyle
5. Vastus lateralis
6. Lateral collateral ligament
7. Patellar tendon
8. Lateral meniscus
9. Iliotibial tract
10. Lateral tibial condyle
11. Biceps
12. Head of fibula
13. Common peroneal nerve
14. Gastrocnemius, lateral head
15. Soleus
16. Muscles of anterior compartment
17. Peroneus longus

Injection and aspiration of the joint is through an anterior approach, and the needle is placed behind the patella. However, this may be achieved from a number of directions: from above (figure 92a); laterally (figure 92 b); medially (figure 92c); or inferiorly, on the lateral or medial side of the patellar tendon (figure 92d,e). Injection may also be undertaken of the prepatellar bursa (figure 93a), and the infrapatellar bursa (figure 93b) and tibial tendon sheath.