[1] In humans, each upper limb is divided into the shoulder, arm, elbow, forearm, wrist and hand,[2] and is primarily used for climbing, lifting and manipulating objects.

In the human body, the muscles of the upper limb can be classified by origin, topography, function, or innervation.

Between them these two joints allow a wide range of movements for the shoulder girdle, much because of the lack of a bone-to-bone contact between the scapula and the axial skeleton.

The pelvic girdle is, in contrast, firmly fixed to the axial skeleton, which increases stability and load-bearing capabilities.

To produce pure flexion or extension at the wrist, these muscle therefore must act in pairs to cancel out each other's secondary action.

[11] In addition, the central group of intrinsic hand muscles give important contributions to human dexterity.

The lumbricals, attached to the tendons of the flexor digitorum profundus (FDP) and extensor digitorum communis (FDC), flex the MCP joints while extending the IP joints and allow a smooth transfer of forces between these two muscles while extending and flexing the fingers.

[11] The motor and sensory supply of the upper limb is provided by the brachial plexus which is formed by the ventral rami of spinal nerves C5-T1.

[15] In primates, the upper limbs provide a wide range of movement which increases manual dexterity.

In contrast, virtually all locomotion functionality has been lost in humans while predominant brachiators, such as the gibbons, have very reduced thumbs and inflexible wrists.

[15] In ungulates the forelimbs are optimised to maximize speed and stamina to the extent that the limbs serve almost no other purpose.

Even-toed ungulates, such as the giraffe, uses both their third and fourth toes but a single completely fused phalanx bone for weight-bearing.

[15] In species in the order Carnivora, some of which are insectivores rather than carnivores, the cats are some of the most highly evolved predators designed for speed, power, and acceleration rather than stamina.

Compared to ungulates, their limbs are shorter, more muscular in the distal segments, and maintain five metacarpals and digit bones; providing a greater range of movements, a more varied function and agility (e.g. climbing, swatting, and grooming).

Other insectivorous species, such as the giant and red pandas, have developed large sesamoid bones in their paws that serve as an extra "thumb" while others, such as the meerkat, uses their limbs primary for digging and have vestigial first digits.

[15] The arboreal two-toed sloth, a South American mammal in the order Pilosa, have limbs so highly adapted to hanging in branches that it is unable to walk on the ground where it has to drag its own body using the large curved claws on its foredigits.