Distal : phalanx

Figure 7.47

(a) The right hand, posterior view. (b) Radiograph of the right hand. Note the small sesamoid bone associated with the joint at the base of the thumb (arrow).

Sesamoid Bone Thumb

Locate and name each of the bones of the upper limb.

Explain how the bones of the upper limb articulate with one another.

It is not uncommon for a baby to be born with an extra finger or toe, but since the extra digit is usually surgically removed early in life, hands like the ones in figure 7.48 are rare. Polydactyly ("many digits") is an inherited trait. It is common in cats. A lone but popular male cat brought the trait from England to colonial Boston. Poly-dactyly is also common in the Amish people.

Pelvic Girdle

The pelvic girdle consists of the two coxae, hipbones, which articulate with each other anteriorly and with the sacrum posteriorly (fig. 7.49). The sacrum, coccyx, and

Figure 7.48

A person with polydactyly has extra digits.

Figure 7.48

A person with polydactyly has extra digits.

Shier-Butler-Lewis: I II. Support and Movement I 7. Skeletal System I I © The McGraw-Hill

Human Anatomy and Companies, 2001

Physiology, Ninth Edition

Essentials of Human Physiology

Essentials of Human Physiology

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