360 : THE MUSCULAR SYSTEM. 
The lumbricales are four small muscles arising in association with the tendons 
of the flexor profundus digitorum in the sole, The jirst muscle arises by a single 
origin from the tibial pide of the tendon of the flexor longus digitorum for the 
second toe; the other three arise by two heads from the adjacent sides of all four 
tendons. Each muscle is inserted into the dorsal expansion of the extensor tendon, 
the metacarpo-phalangeal articulation, and the base of the first phalanx, precisely 
as in the case of the lumbrical muscles of the hand. Each muscle passes forwards * 
on the tibial side of the corresponding toe, superficial to the transverse metatarsal 
ligament. 
The accessorius muscle (m. quadratus plants) arises by two heads: (1) the 
outer tendinous head springs from the outer border of the inferior surface .of the 
os calcis ; (2) the inner head, which 
is fleshy, arises from the inner 
border of the under surface of the 
os calcis. The long plantar liga- 
ment separates the two origins. 
The two heads unite to form a 
flattened band, which is inserted 
into the upper aspect of the tendons 
of the flexor longus digitorum, and 
usually into the tendons destined 
for the second, third, and fourth 
LUMBRICALES Rion toes. 
BREVIS In the leg the flexor longus 
HALLUCIS 36 oe 2 : 
FLEXOR digitorum les at first internal to 
BREVIS MINIMI “T° . . . 
DIGITI ea the tibialis posticus, and is par- 
LONGUS tially concealed by the soleus and 
vee tendo Achillis. Its tendon crosses 
eer over the tibialis posticus above 
LONGUS the ankle, passes beneath the in- 
HALLUCIS 
ternal annular ligament, invested 
by a special synovial sheath, and 
below the ligament crosses the 
plantar or superficial surface of 
the tendon of the flexor longus 
hallucis. As it passes over this 
tendon it receives from it a special 
band of fibres usually associated 
with the tendons for the second 
and third toes. 
In the sole of the foot the tendons 
of the flexor longus digitorum, 
alone with the lumbricales and 
accessorius, and the flexor longus 
hallucis, constitute the second layer 
of muscles of the sole. They are placed between the abductors of the great and 
little toes and the flexor brevis digitorum on the one hand, and the flexor brevis 
and adductors of the great toe on the other. 
The flexor longus hallucis arises on the back of the leg from the lower two- 
thirds of the posterior surface of the fibula, from the fascia over it, and from inter- 
muscular septa on either side. Its tendon passes beneath the internal annular 
ligament enclosed in a special synovial sheath, and after grooving the back of the 
lower end of the tibia, the astragalus, and the under surface of the sustentaculum 
tali of the os calcis, it is directed forwards in the sole of the foot, to be inserted into 
the base of the terminal phalanx of the great toe. 
The muscle is partially concealed in the leg bythe soleus and tendo Achillis. 
It lies at its origin between the tibialis posticus and the peronei muscles, separated 
from the former by the peroneal artery. In the foot, concealed by the abductor 
hallucis, it crosses over the deep aspect of the tendon of the flexor longus 
! 
\\ 
ACCESSORIUS 
ABDUCTOR MINIMI 
DIGITI 
Fic. 265.—THe Muscres or THE RicHr Foor (after 
removal of the first layer). 
