The hand in the human body is made up of the wrist, palm, and fingers. The most flexiblepart of the human skeleton, the hand enables us to perform many of our daily activities.When our hand and wrist are not functioning properly, daily activities such as driving a car,bathing, and cooking can become impossible.
The hand’s complex anatomy consists of
It is important to understand the normal anatomy of the hand in order to learn aboutdiseases and conditions that can affect our hands.
The wrist is comprised of 8 bones calledcarpal bones. These wrist bones connectto 5 metacarpal bones that form the palmof the hand. Each metacarpal boneconnects to one finger or a thumb at ajoint called the metacarpophalangealjoint, or MCP joint. This joint is commonlyreferred to as the knuckle joint.
The bones in our fingers and thumb arecalled phalanges. Each finger has 3phalanges separated by two joints.
The first joint, closest to the knuckle joint,is the proximal interphalangeal joint orPIP joint. The second joint nearer the endof the finger is called the distalinterphalangeal joint, or DIP joint.The thumb in the human body only has 2phalanges and one interphalangeal joint.
Our hand and wrist bones are held in place and supported by various soft tissues.These include:
Cartilage: Shiny and smooth, cartilage allowssmooth movement where two bonescome in contact with each other.
Tendons: Tendons are soft tissue that connectsmuscles to bones to provide support.Extensor tendons enable each finger tostraighten.
Ligaments: Ligaments are strong rope like tissue thatconnects bones to other bones and helphold tendons in place providing stabilityto the joints. The volar plate is thestrongest ligament in the hand andprevents hyperextension of the PIP joint.
Muscles: Muscles are fibrous tissue capable ofcontracting to cause body movement.Interestingly, the fingers contain nomuscles. Small muscles originating fromthe carpal bones of the wrist areconnected to the finger bones withtendons.These muscles are responsible for movement of the thumb and littlefinger enabling the handto hold and grip items by allowing the thumb to move across the palm, a movement referredto as Thumb Opposition. The smallest muscles of the wrist and hand are responsible for finemotor movement of the fingers.
Nerves: Nerves are responsible for carrying signals back and forth from the brain to muscles in ourbody, enabling movement and sensation such as touch, pain, and hot or cold.The three main nerves responsible for hand and wrist movement all originate at theshoulder area and include the following:
Blood Vessels: The two main vessels of the hand and wrist are
Bursae: Bursae are small fluid filled sacs thatdecrease friction between tendons andbone or skin. Bursae contain special cellscalled synovial cells that secrete alubricating fluid. When this fluid becomesinfected, a common painful conditionknown as Bursitis can develop.
Biomechanics is a term to describe movement of the body.The fingers of the hand permit the following movements at themetacarpophalangeal joint (MCP) or knuckle joint.
Biomechanics of the wrist include the following
The thumb performs different movements at three separate joints. The carpometacarpaljoint is where the wrist bones, carpals, meet the metacarpals, the bones in the palm of thehand. At this articulation, the following movements can be performed
The following movements occur at the metacarpophalangeal joint or MCP joint at the baseof the thumb
At the interphalangeal joint of the thumb or IP joint, the following movements can beperformed: