Hand Anatomy Systems Overview

Study Notes

Hand Anatomy

Hand anatomy is composed of several interconnected systems, each with its own set of components crucial for function. These systems consist of bone structures, nerve pathways, joint connections, and muscle networks. Here's a closer look at these essential features:

Bones of the Hand

The human hand contains 27 bones organized into three main sections:

Wrist

At the wrist level, there are eight carpal bones. They form two rows — four proximal carpals and four distal carpals. Lying between them is one radius bone, which articulates with both sets of carpals.

Midcarpal Level

Between the forearm and fingers, there are five metacarpal bones that articulate directly with the wrist row of carpal bones. Each finger has only one metacarpal bone, except for the thumb, which has two.

Fingers

Each finger consists of three phalanges in total - the thumb having two fewer than other fingers. Proximally to the knuckles, there are two phalanxes; while distally, there is a single phalange per finger. Together, they make up 19 individual phalanges.

Nerves of the Hand

There are three major branches of the ulnar nerve running through the hand, all originating from the medial epicondyle of the humerus. They extend downwards along the ulna, passing by the artery and vein before crossing over to the radial side of the hand near the wrist. The common digital nerve runs parallel to the first branch, dividing into two end nerves to supply blood and innervation to the skin under the index and middle fingers, respectively. The third branch supplies sensation to the little finger, including parts of the fourth digit, due to small overlaps in their sensory territories.

Joints of the Hand

In addition to numerous joint spaces where tendons attach to bones, most bony hand joints are synovial, allowing movement within limited ranges of motion:

Between carpal bones are multiple movable joints called radiocarpal joints, forming the wrist.
Metacarpophalangeal joints connect the ends of the metacarpal bones to the bases of the phalanges.
Interphalangeal joints link the shafts of adjacent phalanges together, enabling flexion and extension.

Muscles of the Hand

Muscles responsible for moving hands can be classified into three categories according to their locations around the palm: extensor muscles, flexor muscles, and intrinsic muscles. Extensors run toward the back of the arm from the elbow towards the wrist and fingers, while flexors actuate towards the palmar surface. Intrinsics lie deep within the palm and have direct contact with the base portions of digits.

To sum up, understanding hand anatomy involves grasping the roles of bones, nerves, joints, muscles, ligaments, tendons, and miscellaneous soft tissues working together like an intricate, well-oiled machine—allowing us to perform delicate tasks requiring fine motor skills.

Description

Explore the interconnected systems of hand anatomy including bones, nerves, joints, and muscles. Learn about the structures and functions of various components in the human hand to gain insights into its complex mechanisms.