digitorum, to which it is connected by a strong fibrous band destined for the 
tendons for the second and third toes. At the root of the great toe the tendon 
occupies the interval between the insertions of the flexor brevis hallucis. 
The tibialis posticus muscle (m. tibialis posterior) has a fourfold origin in the 
leg. It arises (1) from the middle three-fifths of the shaft of the fibula between 
the oblique line and the interosseous border; (2) from the middle third of the back 
of the tibia between the vertical line and ‘the interosseous border; (3) from the 
interosseous membrane; and (4) from the fascia over it and the septa on either 
side. The muscle gives rise to a strong tendon which passes beneath the internal 
annular ligament, Invested by a special synovial sheath, and grooves the back of 
the internal malleolus, on its way to the inner border of the foot. Its tendon then 
spreads out and is inserted by three bands 
into (1) the navicular and internal cunei- 
form bones, (2) the second, third, and fourth 
metatarsal bones, the middle and external 
cuneiform and the cuboid bones, and (3) 
by a recurrent slip into the inner border of 
the sustentaculum tali of the os calcis 
(Fig. 262). 
In the leg the tibialis posticus is con- 
cealed, as it hes on the interosseous mem- 
brane between the tibia and fibula, by the 
superficial muscles and the posterior tibial 
vessels and nerve. It les between the 
flexor longus hallucis and flexor longus 
digitorum, “and is crossed by the tendon of 
the latter muscle just above the ankle. In 
the foot its tendon is covered by the long 
flexor tendons and by the short flexor 
muscles of the great toe. The tendon is 
in contact with the inferior calcaneo- 
navicular ligament in the interval between axpucror Cu BREVIS — 
the sustentaculum tali and the navicular ‘JM Terese 
bone. 
THE MUSCLES IN THE SOLE OF THE FOOT. 361 
FLEXOR 
LONGUS 
HALLUCIS 
ABDUCTOR 
HALLUCIS 
The peroneo-calcaneus muscle, when present, 
arises from the fibula, and is inserted into the os PLANTAR 
5 ain irs PLANTAR FASCIA 
caleis. FASCIA 
THE MUSCLES IN THE SOLE OF THE Foor. 
The muscles in the sole of the foot are 
divisible into four layers placed beneath 
the plantar fascia. 
First layer: Abductor hallucis, flexor 
brevis digitorum, abductor minimi digiti. 
Second layer: Lumbricales and accessorius, together with the tendons of the 
flexor longus hallucis and flexor longus digitorum. 
Third layer: Flexor brevis hallucis, adductors of the great toe, and flexor 
brevis minimi digiti. 
Fourth layer: Interossei (plantar and dorsal). 
The abductor hallucis has a double origin from (1) the greater tubercle on 
the tuberosity of the os calcis, and (2) the internal annular ligament and plantar 
fascia. Lying superficially along the inner border of the sole, its tendon i is inserted, 
along with part of the flexor brevis hallucis, into the inner side of the'first phalanx 
of the great toe. The muscle ¥ beneath the plantar fascia, internal to the flexor 
brevis digitorum, and conceals the plantar vessels and nerves, and near its origin 
the long flexor tendons. 
The flexor brevis digitorum has likewise a double origin: (1) from the 
fore-part of the greater tubercle of the tuberosity of the os calcis, and (2) from 
a 
Fic, 266.—THE MUSCLES OF THE RicHt Foot 
(after removal of the plantar fascia), 
