Pre-lab Exercise: Vessels of the Upper Limb. The distinction of these extensor muscles as superficial or deep is much less precise than it was in the flexor compartment. Some consider there to be a single extensor compartment with digital and thumb muscles. The deep group comprises all the extensors of the thumb, plus a separate extensor for the index finger and a supinator that originates on the humerus.
In this article, we shall be looking at the anatomy of the intrinsic muscles of the hand. The thenar muscles are three short muscles located at the base of the thumb. The muscle bellies produce a bulge, known as the thenar eminence. They are responsible for the fine movements of the thumb.
The wrist links the hand to the arm. The wrist is a complex mechanical system of 8 small bones known as the carpal bones. The carpal bones are arranged in 2 interrelated rows. One row connects with the ends of the bones in the forearm— radius and ulna.
A hand is a prehensile , multi- fingered appendage located at the end of the forearm or forelimb of primates such as humans , chimpanzees , monkeys , and lemurs. A few other vertebrates such as the koala which has two opposable thumbs on each "hand" and fingerprints extremely similar to human fingerprints are often described as having "hands" instead of paws on their front limbs. The raccoon is usually described as having "hands" though opposable thumbs are lacking. The human hand normally has five digits: four fingers plus one thumb ;   these are often referred to collectively as five fingers, however, whereby the thumb is included as one of the fingers. The metacarpal bones connect the fingers and the carpal bones of the wrist.