58 
MAMMALIAN ANATOMY 
Name of muscle 
Origin 
Insertion 
23. Extensor digitorum com¬ 
munis. 
Anterior surface of the distal 
end of the femur, external 
to the anterior intercondy- 
loid fossa, the tendon of 
origin passing through the 
capsule of the knee joint. 
Distally the muscle divides 
into four tendons which 
pass under the annular 
ligament, and are inserted 
into the middle and distal 
phalanges of the four digits. 
24. Extensor digiti secondi. 
Medial surface of proximal 
end of tibia. 
Unites with the first tendon 
of the extensor digitorum 
communis (23). 
25. Triceps surae, consisting of: 
(a) Gastrocnemius, a large 
two headed muscle 
forming the larger part 
of the calf of the leg. 
1. Medial head..*.... 
Medial epicondyle of femur 
and medial sesamoid of 
knee joint. 
The two parts of the gastro¬ 
cnemius and the soleus unite 
to form a large strong ten¬ 
don, the tendo calcaneus 
(of Achilles), which is in¬ 
serted into the extremity of 
the tuber of the calcaneum. 
2. Lateral head. 
Lateral epicondyle of femur 
and lateral sesamoid of 
knee joint. 
(b) Soleus. 
Head of fibula. 
26. Plantaris ( = flexor digitorum 
sublimis of hand) en¬ 
wrapped by the gastrocne¬ 
mius (25a). 
Posterior surface of the 
femur proximal to the 
lateral epicondyle, and from 
the lateral sesamoid of the 
knee joint. 
Its tendon divides into four 
slips, each of which divides 
at the base of the proximal 
phalanx into two slips, 
which pass on either side of 
the phalanx, and are in¬ 
serted into the proximal end 
of the middle phalanx. 
27. Popiiteus. 
Lateral epicondyle of femur. 
Proximal region of posterior 
surface of the tibia. 
28. Flexor digitorum communis 
(= flexor digitorum pro¬ 
fundus of the hand). 
Head of fibula and posterior 
surface of proximal region 
of both fibula and tibia. 
Four tendinous slips, each of 
which passes between the 
two slips into which each 
tendon of the plantaris (26) 
divides, and is inserted into 
the terminal phalanx of the 
digit. 
29. Peroneus longus. 
Lateral condyle of tibia. 
Cuboid. 
30. Peroneus brevis. 
Lateral condyle of tibia. 
Proximal end of fifth (last) 
metatarsal. 
31. Peroneus quarti digiti. 
Shaft of fibula. 
Distal end of fourth (ap¬ 
parent third) metatarsal. 
32. Peroneus quinti digiti. 
Lateral condyle of tibia and 
head of fibula. 
Distal end of fifth (last) 
metatarsal. 
