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The inferior surface is oval, concave from side to side, convex from before backward, so as to form a saddle-shaped surface for articulation with the base of the first metacarpal bone. This saddle-shaped articulation is partially responsible for the thumb's opposable motion. The dorsal surface is smooth. The palmar surface is narrow and rough.
The thumb contrasts with each of the other four fingers by being the only one that: Is opposable to the other four fingers; Has two phalanges rather than three. However, recently there have been reports that the thumb, like other fingers, has three phalanges, but lacks a metacarpal bone. [3]
As its name suggests, it opposes the thumb, bringing it against the fingers. This is a very important movement, as most of human hand dexterity including grip comes from this action. The abductor pollicis brevis originates on the scaphoid tubercle and the flexor retinaculum. It inserts to the radial sesamoid bone and the proximal phalanx of the ...
The radial nerve innervates the finger extensors and the thumb abductor; that is, the muscles that extend at the wrist and metacarpophalangeal joints (knuckles) and abduct and extend the thumb. The median nerve innervates the flexors of the wrist and digits, the abductors and opponens of the thumb, the first and second lumbricals. The ulnar ...
A long bone is one that is cylindrical in shape, being longer than it is wide. However, the term describes the shape of a bone, not its size, which is relative. Long bones are found in the arms (humerus, ulna, radius) and legs (femur, tibia, fibula), as well as in the fingers (metacarpals, phalanges) and toes (metatarsals, phalanges).
the digital/phalangeal region encompassing the fingers. The thumb is referred to as the pollex. The posterior view contains, from superior to inferior, the cervical region encompassing the neck, the scapular region encompassing the scapulae and the area around, the dorsal region encompassing the upper back; the lumbar region encompassing the ...
Three phalanges are present on each finger and toe, with the exception of the thumb and big toe, which possess only two. The middle and far phalanges of the fourth and [citation needed] fifth toes are often fused together (symphalangism). [1] [2] The phalanges of the hand are commonly known as the finger bones. The phalanges of the foot differ ...
The ankle is the tarsus and tarsal, and the heel is the calcaneus or calcaneal. The foot is the pes and pedal region, and the sole of the foot the planta and plantar. As with the fingers, the toes are also called the digits, phalanges, and phalangeal area. The big toe is referred to as the hallux. [1]