Fundamentals of Anatomy and Physiology

168

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Figure 7- 24 (C) A tibia and fibula. (Continued)
the hindfoot are the calcaneus (kal-KAY-nee-us), some-
times called the calcaneum, which is the largest of the tarsal
bones and forms the heel, the talus or ankle bone, the
navicular (nah-VIK-you-lar), and the cuboid (KYOO-
boyd). Because the calcaneus or heel bone receives the weight
of the body when walking, it has developed as the largest of
the tarsal bones. The tarsal bones of the

CHAPTER

forefoot are the medial (I), intermediate (II), and lateral

(III) cuneiforms (kyoo-NEE-ih-formz).

The rest of the forefoot bones are the metatar-sals

and phalanges. There are five metatarsal bones in the

forefoot. Each is classified as a long bone based on shape

and each has a base, shaft, and a head. The heads formed at

the distal ends of the metatarsals form what we call the ball

of the foot. The bases of the first, second, and third

metatarsals articulate with the three cuneiforms; the fourth

and fifth metatarsals articulate with the cuboid. The

intrinsic muscles of the toes are attached to the shafts of the

metatarsals. The first meta-tarsal is the largest due to its

weight-bearing function during walking.

The phalanges of the toes are classified as long bones

despite their short length because again they have a base,

shaft, and head (see Figure 7- 2 5B). They have the same

arrangement as the phalanges of the fingers. There are two

phalanges in the great toe, proximal and distal. The

proximal one is large due to its weight-bearing func-tion

when walking. The other four toes have three each,

proximal, middle, and distal phalanges.

Fibula

Calcaneus

Figure 7- 25

Phalanges

Metatarsals

Tibia

Talus^

NavicularSecond cuneiform

Third cuneiform^

Metatarsal II

Tarsals^

Phalanges

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Learning Cuboid Base Shaft Head Cengage ©
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(A) Right ankle and foot, lateral view. (B) Right ankle and foot, superior view.
Distal phalanx
Middle phalanx
Proximal phalanx
First cuneiform
Second cuneiform
Third cuneiform
Cuboid
Navicular
Talus
Calcaneus
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