Thumb

In human anatomy, the thumb is the first digit on a hand. The human thumb is fully opposable to the tips of the other fingers in that it may position itself, and be folded inward, toward the rest of the hand and fingers, if so required. It rotates at the carpometacarpal joint and so can complete the sometimes quite delicate task of grasping objects by pressing them against the rest of the hand or finger(s).

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In anatomy, the thumb is also called the first finger, pollex, digitus primus, or digitus I.

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The thumb consists of 3 bones:

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• distal phalanx (of the first digit)
• proximal phalanx (of the first digit)
• first metacarpal

Its movements are controlled by eight muscles:

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• opponens pollicis
• abductor pollicis brevis
• flexor pollicis brevis
• adductor pollicis
• flexor pollicis longus
• abductor pollicis longus
• extensor pollicis brevis
• extensor pollicis longus

The first four of these muscles are in the hand and the first three of these form the thenar eminence. The other muscles come from the forearm. The extensor pollicis longus tendon and extensor pollicis brevis tendon form what is know as the anatomical snuff box (an indentation on the lateral aspect of the thumb at its base) where one can usually palpate the radial artery.

Thumb: Anatomy of the thumb ►



 

Human anatomy: Human anatomy or anthropotomy is a special field within anatomy. It studies organs and organ systems of the human body, leaving the study of tissues to histology and cells to cytology....

Hand: The hand (med./lat.: manus) is the portion of the arm or anterior limb of a human or other primate, where the appendage terminates. This part of the limb is especially used in grasping and holding. Each hand is a mirror image of the other....

Finger: :For the network protocol, see finger protocol. For the hand gesture, see the finger....




Thumb related Images and Photos (experimental)

Tom Thumb	Thumb Butte Prescott Arizona	Thumb Butte Prescott Arizona	Thumb-Size R/C Lamborghini
Thumb Stadium Electronic Game Kit	Tom Thumb- Illustration to 'Le petit Poucet'	Star Wars Mimobot Thumb Drives	Star Wars Mimobot Thumb Drives
Star Wars Mimobot Thumb Drives	DC Comics Mimobot Thumb Drives	Illustration from 'Tom Thumb' by the Brothers Grimm