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A. The attachments on the dorsal aspect of the skeleton of the foot are as follows (Fig. 3.69)

1. The gastrocnemius, the soleus and the plantaris are inserted through the tendocalcaneus into the middle of the posterior surface of the calcaneus.

Fig. 3.70. Skeleton of right foot, showing attachments. seen from the ventral aspect.

2. The peroneus brevis is inserted into the lateral side of the base of the fifth metatarsal bone.

3. The peroneus tertius is inserted on the dorsal surface of the base of the fifth metatarsal bone.

4. The extensor digitorum longus ends in four tendons, one for each of the lateral four digits. The tendon for each digit ends in three slips, one intermediate and two collateral. The intermediate slip is inserted into the base of the middle phalanx; and the collateral slips are inserted into the base of the distal phalanx.

5. The extensor hallucis longus is inserted into the dorsal aspect of the base of the distal phalanx of the great toe.

6. The extensor digitorum brevis takes origin from the anterior part of the superior and lateral aspects of the calcaneus.

7. The extensor hallucis brevis (a part of the extensor digitorum brevis) is inserted into the dorsal surface of the base of the proximal phalanx of the great toe

B. The tendons descending from the leg to gain insertion on to the plantar aspect of the skeleton of the foot are as follows(Fig. 3.70)

1. The tibialis posterior is inserted mainly into the tuberosity of the navicular bone and the medial cuneiform bone.

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Slips from the tendon (not shown in the diagram) also reach the sustentaculum tali, the intermediate cuneiform bone, the lateral cuneiform bone, the cuboid, and the bases of the 2nd, 3rd and 4th metatarsal bones.

2. The tibialis anterior is inserted into the medial cuneiform bone (on its medial and plantar aspects) and into the medial side of the base of the first metatarsal bone.

3. The peroneus longus is inserted into the lateral side of the medial cuneiform bone, and into the lateral side of the base of the first metatarsal bone.

4. See peroneus brevis, above.

5. The flexor hallucis longus is inserted into the plantar aspect of the base of the distal phalanx of the great toe.

6. The flexor digitorum longus is inserted into the plantar surfaces of the bases of the distal phalanges of all digits except the great toe.

C. The attachments of intrinsic muscles of the foot (excluding the interossei) on the plantar aspect of the skeleton of the foot are as follows(Fig. 3.70)

1. The flexor digitorum brevis arises from the medial process of the tuberosity of the calcaneus.

The muscle ends in four tendons, one for each of the lateral four toes. Each tendon divides into two slips attached to the medial and lateral sides of the middle phalanx of the digit concerned.

2. The flexor digitorum accessorius arises from the calcaneus by two heads. The lateral head arises from the lateral process of the tuberosity, and the medial head from the medial surface, inferior to the groove for the tendon of the flexor hallucis longus. (Note that this muscle does not have a bony insertion).

3. The flexor hallucis brevis arises from the plantar surfaces of the cuboid and lateral cuneiform bones. At its insertion the muscle divides into two parts, medial and lateral, that are attached to the corresponding sides of the base of the proximal phalanx of the great toe. (Also see below).

4. The abductor hallucis takes origin from the medial process of the calcaneal tuberosity. It is inserted into the medial side of the base of the proximal phalanx of the great toe (along with the medial part of the flexor hallucis brevis).

5. The adductor hallucis (oblique head) arises from the bases of the 2nd, 3rd, and 4th metatarsal bones (and also from the sheath of the peroneus longus).

(Note: The transverse head of the muscle does not have a bony origin. It arises from the ligaments on the plantar aspect of the metatarsophalangeal joints of the 3rd, 4th, and 5th toes).

The muscle is inserted into the lateral side of the base of the proximal phalanx of the great toe (along with the lateral part of the flexor hallucis brevis).

6. The abductor digiti minimi takes origin from both the lateral and medial processes of the tuberosity of the calcaneus. It is inserted into the lateral side of the proximal phalanx of the 5th toe (along with the flexor digiti minimi brevis).

7. The flexor digiti minimi brevis arises from the plantar surface of the base of the 5th metatarsal bone. It is inserted into the lateral side of the proximal phalanx of the 5th toe (along with the abductor digiti minimi).

D. The attachments of the interossei of the foot are as follows(Figs. 3.71, 3.72) 1. The first plantar interosseous muscle arises from the plantar aspect of the shaft of the third metatarsal bone. The second plantar interosseous muscle has a similar origin from the fourth metatarsal; and the third plantar interosseous muscle from the fifth metatarsal. The plantar interossei are inserted into the medial side of the base of the proximal phalanx of the corresponding digit (and also into the dorsal digital expansion).

2. Each dorsal interosseous muscle arises from the adjacent sides of the shafts of two metatarsal bones as follows:

Fig. 3.71. Attachments of plantar interossei.1 to 5.

Metatarsal bones.

(a) The first muscle from the 1st and 2nd metatarsals.

(b) The second muscle from the 2nd and 3rd metatarsals.

(c) The third muscle from the 3rd and 4th metatarsals.

(d) The fourth muscle from the 4th and 5th metatarsals.

The dorsal interossei are inserted as follows.

(a) The first muscle on the medial side of the base of the proximal phalanx of the 2nd digit.

(b) The second muscle on the lateral side of the base of the proximal phalanx of the 2nd digit.

(c) The third muscle on the lateral side of the base of the proximal phalanx of the 3rd digit.

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(d) The fourth muscle on the lateral side of the base of the proximal phalanx of the 4th digit.

E. Other attachments on the bones of the foot.

1. The bones of the foot give attachment to numerous ligaments connected with the ankle, intertarsal, and tarsometatarsal joints; and with the joints of the digits. The more important of these are as follows.

(a) The anterior and posterior talofibular ligaments are attached to the lateral side of the talus.

(b) The anterior and posterior tibiotalar ligaments are attached on the medial side of the talus.

(c) The calcaneofibular ligament is attached to the lateral surface of the calcaneus.

Fig. 3.72. Attachments of dorsal interossei of the foot.1 to 5. Metatarsal bones.

(d) The cervical ligament is attached (above) to the inferolateral aspect of the neck of the talus; and (below) to the superior surface of the calcaneus.

(e) The long plantar ligament is attached posteriorly to the plantar surface (tuberosity) of the calcaneus; and anteriorly to the plantar surface of the cuboid bone distal to the groove for the peroneus longus (Fig. 3.70). Some fibres of the ligament reach the bases of the 2nd, 3rd, and 4th metatarsal bones.

(f) The short plantar ligament passes from the anterior tubercle of the calcaneus to the cuboid bone (proximal to the groove for the peroneus longus) (Fig. 3.70).

(g) The plantar calcaneonavicular ligament or spring ligament passes from the anterior margin of the sustentaculum tali of the calcaneus to the plantar surface of the navicular bone (Fig.3.70).

(h) The bifurcate ligament is Y-shaped. The stem of the ‘Y’ is attached (posteriorly) to the upper surface of the calcaneus. The limbs are attached (anteriorly) to the dorsal aspect of the cuboid and navicular bones.

(i) The interosseous talocalcaneal ligament passes from the sulcus tali (on the talus) to the sulcus calcanei (on the calcaneus).

2. The lateral end of the inferior extensor retinaculum (of the ankle) is attached to the upper surface of the calcaneus.

3. The lower end of the flexor retinaculum (of the ankle) is attached to the medial surface of the calcaneus.

4. The peroneal retinacula are attached to the lateral surface of the calcaneus.

5. The fibrous flexor sheath of each digit is attached to the sides of the phalanges, on the plantar aspect.

Ossification of the Bones of the Foot

The calcaneus has one main centre of ossification that appears in the third fetal month; and a secondary centre (for a scale like epiphysis that covers its posterior part) that appears in the 6th to 8th years.

All other tarsal bones normally have one centre each which appears as follows.

Talus --- 6th fetal month

Cuboid --- Just before or after birth

Medial cuneiform --- 3rd year

Intermediate cuneiform --- 1st year

Lateral cuneiform --- 1st year

Navicular --- 3rd year

Each metatarsal bone has a primary centre for the shaft appearing in the 9th or 10th fetal week. The first metatarsal has a secondary centre for its base appearing in the 3rd year. The other metatarsals have secondary centres for their heads (not bases) appearing in the 3rd or 4th year. The secondary centres unite with the shafts between the 17th and 20th years.

Each phalanx has a primary centre for the shaft (appearing in the 7th to 15th fetal weeks);

and a secondary centre for the base (appearing between the 2nd to 8th years) which unites with the shaft by the 18th year.

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