Understanding the Anatomy of the Hand




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The human hands are complex and capable of a wide range of functions, including gross and fine motor movements. Gross motor movement is considered moves that allow you to pick up large objects or perform heavy labor. Fine motor movements are functions that enable you to perform a delicate task such as hold small objects, performing detailed work, such as surgeon conducting an operation.

The complex abilities of the human hand are part of what make humans unique. Only humans have the capacity to bring our thumbs across the hand to connect the ring and pinkie fingers. This ability provides human with the dexterity to use tools and give us a forceful grip.

The hand consists of four segments

The fingers – Digits that extend from the palm of the hand, the hands make it possible for humans to pick up or grip very small objects.
Palm: this the bottom of the body of the hand.
Back (opisthenar): The back of the hand reveals the dorsal venous network, a web of veins.Anatomy-of-hand

Wrist: This is the connection point between the arm and the hand, the wrist enables hand movement,

Finger Anatomy: Unfortunately the finger is easily injured, broken fingers are the most common traumatic injury seen in the emergency room. Finger fractures account for nearly 10% of all bone features. Since fingers are used for a large majority of everyday activities for humans, they tend to be at higher risk than other parts of the body. For traumatic injury, sports injury, workplace injuries or accidents.Anatomy-of-hand3

These finger injuries are easier to understand when you know how the fingers are constructed. The fingers consist of ligaments, that are strong tissue that connects different bones together, tendons are attachments of bone and tissue., and three bones called phalanges. There are no muscles in the fingers, and fingers move by the pull of forearm muscles of the tendons. The three bones in each finger are referenced or named according to their relationship to the palm of the hand.Anatomy-of-handr
Each hand consists of 19 bones. The palm includes five metacarpals, and each finger except the thumb consist of one proximal phalanx, one middle phalanx, and one distal phalanx. The thumb does not have a central phalanx. Each bone is connected by a grouping of ligaments.

The distal phalanges are one of three kinds of finger bones. The hand and wrist are composed of three distinct bone groups. The carpals are the foundation or based on the hand and wrist, and contain eight small bones with unique names. Preceding them the metacarpals form the base of the fingers, and the phalanges also called the fingers. The phalanges are included of the proximal, middle, and distal groups. The proximal bones are positioned just underneath the knuckle, while the middle bones are positioned above the knuckle. The distal phalanges are the fingertips. This is the reason the term terminal phalanges may be undifferentiated from the term distal phalanges. These bones are different their equivalents in the finger. Their main purpose involves holding the sensitive flesh of the fingertip, where a large number of nerve endings are located. These nerve endings transmute sensory sensations of touch into nerve impulses that are conveyed back to the brain. These bones also emphasize apical tufts, which are flat extensions of bone. The tufts hold the fingernails on the dorsal side of the fingers, and the corpulent pad of skin on the palmar surface of the fingers

In hand, the distal phalanges are flat on their palmar surface, small, and with a coarse, raised surface of horseshoe formation on the palmar surface, supporting the finger pulp .In the phalanges of the hand the low, wide expansions found at the tips of the distal phalanges are called apical tufts. They support the fingertip pads and nails. The phalanx of the thumb has a noticeable inclusion for the flexor pollicis longus (asymmetric in the direction of the radial side), an ungual fossa, and two uneven ungual spines (the ulnar being more prominent). This asymmetry is crucial to ensure that the thumb pulp is constantly facing the pulps of the other digits, an osteological arrangement which provides the maximum contact surface for objects that are held by the hand.

 

Each fingertip –distal phalanx and accompanying tissues contain a fingernail. These structures are built from keratin, a rough, sturdy protein. Similar types of keratin also make up human hair, the scales and claws of reptiles, and the claws, beaks, and feathers of birds.

 

The palm of the hand does not contain melanin or skin pigment or hair follicles. The only other place on the body that takes both these is the sole of the fit. These two parts of the body also have thicker skin than other parts of the body.

The wrist joint is a complex joint that exists between distal ends (furthest from the body) of the radius and Ulna (two forearm bones) and the carpal bones. It connects the forearm to the hand and provides a good range of motion. Repeated use does however frequently lead to injuries.Anatomy-of-hand4

Bones within the wrist is the Ulna; which is the larger of the two forearm bones. However, it tapers at the wrist end and gets narrow than the radius at the point of the wrist. The Radius is positioned on the thumb side of the wrist, and the ulna on the little finger side.

The Ulna and radius bones form the wrist joint along with the carpal bones. There are a total of 8 carpal bone that arrange in two rows, proximal and distal;

Lunate -proximal
Triquetrum – proximal
Pisiform – proximal
Capitate – distal
Trapezium – distal
Trapezoid – distal
Hamate – distal
Scaphoid

The scaphoid bone crosses both the proximal and distal rows; it is the largest carpal bone. The scaphoid and the lunate are the two bones which actually articulate with the radius and ulna to of the wrist joint.

Wrist Ligaments

Each bone inside the wrist is joined to the next bone to it or by one or more ligaments. You can assume, these appears in a large number of ligaments of the wrist are the medial (ulnar) and lateral (radial) collateral ligaments, The MCL moves from the distal end of the ulnar and crosses the wrist to connect to the triquetrum and the pisiform. The LCL passes from the edge of the radius, across the joint to the scaphoid.Anatomy-of-hand5

Wrist Muscles

First muscles act on the wrist joint, is situated within the forearm, with only the tendon passing the joint and inserting on the hand. The muscles on the back of the forearm (dorsal aspect) act to extend the wrist or pull it backs as if pulling a ring-pull.

Extensor digitorum communis
Extensor carpi ulnaris
Extensor carpi radialis brevis
Extensor carpi radialis longus
Extensor pollicis longus

The muscles on the front of the forearm (palmer aspect) act to flex the wrist, such as when you push a roundabout:

Flexor carpi ulnaris
Flexor digitorum superficialis
Flexor carpi radialis
Flexor pollicis longus

Some of these muscles can help to perform radial and ulnar deviation. Radial deviation is the act of tilting the wrist in a radical direction (or with the thumb leading) Extensor carpi radials Brevis, longus and flexor carpi radialis all perform this movement. Ulnar deviation is the reverse movement, of tilting the wrist so that the small finger leads. Extensor carpi ulnaris and flexor carpi ulnaris perform this movement.

Nerves
These nerves pass from the forearm, across the wrist into the hand

Radial nerve; The radial nerve is on the radial, or thumb sied of the wrist joint. Its provides feeling to the bank of the hand from the thumb to the middle finger.

Median nerve
The median nerve handles the development of carpal tunnel syndrome. It passes through the carpal tunnel and splits into four branches which each travels to the thumb and next three fingers. It provides sensation to all of these fingers although only the within half of the ring finger.

Ulnar nerve
The ulnar nerve provides the small finger and the other half of the ring finger.

Although fully functional hand can accomplish many things, they ae susceptible to a number conditions.

Fractured/Broken bones
Sprains, cuts, bruises, strains
Arthritis
Nerve Disorders
Finger Clubbing
Tendinitis


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