Comprehensive Guide to Hand Anatomy: Parts, Functions & Diagram

Overview of Hand Anatomy

The human hand is a fantastic part of the upper limb, designed for both strength and precision. It is crucial for feeling and doing things with our hands. It can handle challenging tasks like climbing mountains and delicate actions like manipulating small objects. Hand anatomy consists of bones, muscles, and neurovascular structures that work together. They help us touch, hold, and move objects every day. While intrinsic hand muscles of hand anatomy play a role, forearm muscles also send tendons through the wrist, allowing for a wide range of movements. They are like our built-in tools for interacting with the world around us!

In this article, we will see the hand anatomy with its different parts and functions to get detailed information about the hand.

Hand Anatomy Diagram

Hand Anatomy, Parts, Names & Diagram

Anatomy of the Hand

Internal Parts of a Hand

  • Bones
    • Phalanges
    • Metacarpals
    • Carpals
  • Joints
  • Ligaments
  • Muscles
  • Synovial lining
  • Volar plates
  • Tendon sheaths
  • Tendons
  • Blood vessels
  • Nerves
  • Palmar fascia

External Parts of a Hand

  • Fingers
  • Thumb
  • Index finger
  • Middle finger
  • Ring finger
  • Little finger
  • Palm
  • Wrist
  • Knuckle
  • Fingernail

Hand Anatomy – Parts & Functions

Hand Bone Anatomy

The skeletal system of the human body serves as an essential structure. It supports and safeguards the body’s critical organs and tissues.

Among all the bones in the body, the ones in the hand are the most crucial. They enable complex movements required for gripping, object manipulation, and executing sensitive motor tasks.

These strong foundations are necessary for the hand to maintain shape and stability, making tasks simple. The parts of the hand benefit from the strength and rigidity of bones, which act as an internal framework to ensure optimal performance.

Phalanges

Phalanges are the bones in our fingers and toes, with 14 in each hand and foot. They come from the Greek meaning “bone of finger or toe.”

Each finger and toe has three types of phalanges: proximal, middle, and distal. However, the thumb and big toe each have only two phalanges.

The distal phalanx is at the very tip and carries the nail. Its base curves inward gets narrower towards the end and then widens into a bump.

Metacarpals

The metacarpus is a group of five bones in the hand between the wrist and fingers. They’re called long bones because they’re similar in structure to other long bones in the body.

Every metacarpal bone consists of a shaft with a rounded head at one end and a broad base at the other. At the head, they join the finger and wrist bones at the base. From the thumb side, they are numbered 1 through 5.

The place on the back of the hand where knuckles form is a flat, triangular region that appears before the fingers.

The palm muscles are housed in concave regions on the palm side of the bones. The rounded head at the end of each bone forms the knuckle prominence. These heads attach to the finger bones at the metacarpophalangeal joint.

Carpals

The wrist comprises eight small carpal bones arranged in two rows: one closer to the forearm and the other to the hand. Each bone has a distinct form designed to fit surrounding muscles, ligaments, and adjacent bones.

The first row, adjacent to the forearm, consists of the scaphoid, lunate, triquetrum, and pisiform. In contrast, closer to the hand, the second row comprises the trapezium, trapezoid, capitate, and hamate.

These bones facilitate smooth movement of the hand and wrist while providing essential support to the surrounding soft tissues.

Additionally, they play a crucial role in the wrist’s structural framework and create pathways for nerves and blood vessels.

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Hand Anatomy – Joints

With the help of different hand joints, we can carry out many actions accurately and skillfully. They allow us to perform intricate movements with precision and accuracy.

These specialized areas where the phalanx bones connect provide support and flexibility. They are necessary for bending, straightening, twisting, and grasping objects.

Their complex and diverse design sets these joints apart. There are various types of joints, each with a unique function. The hinge joint at the base of each finger facilitates smooth bending and straightening movements.

Wrist Joint

One critical synovial junction is the radiocarpal joint. It connects the scaphoid, lunate, and triquetral tiny wrist bones to your forearm bone (radius).

It allows you to move your wrist up, down, and side to side. The lower end of the radius generates a substantial concave surface at the radiocarpal joint, which interacts directly with the scaphoid and lunate bones. This joint facilitates a wide range of wrist motions, including grasping, raising, and rotating the hand.

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Carpometacarpal Joint

The carpometacarpal (CMC) joints connect the wrist and hand bones. There are five of these joints, with the thumb’s joint being the most flexible.

The other four joints link the middle hand bones to the wrist bones. Together, these form the typical carpometacarpal joint.

These joints allow for different degrees of movement. The ones closer to the thumb allow more movement, while the ones further away have less.

This setup stabilizes the wrist and hand while allowing flexibility for tasks like holding objects.

Hand Ligament Anatomy

The hand and wrist are kept stable and robust by rugged bands of tissue called ligaments. These ligaments have essential jobs in maintaining structure and function:

  1. Collateral Ligaments: These are on the sides of the fingers and thumb, stopping them from moving too much sideways.
  2. Volar Plate: Found under the finger bones on the palm side, it stops the fingers from bending backward.
  3. Palmar Fascia: This thick, triangular structure under the palm skin helps the hand keep its shape during movement and prevents the skin from sliding when holding things.
  4. Ulnocarpal and Radiocarpal Ligaments stabilize the entire wrist joint, ensuring movement is smooth and controlled.
  5. Volar Carpal Ligaments: Supporting the underside of the wrist, they add to its stability and function.
  6. Dorsal Radiocarpal Ligaments: These ligaments on the back of the wrist offer extra support, especially when bending the wrist backward.

Hand Muscle Anatomy

The hands contain 34 muscles, which healthcare providers categorize into distinct groups, each with its unique functions:

  1. Thenar muscles: These muscles control the movement of the thumb. They are located at the base of the thumb in the palm, and their contraction can be felt as a bulge in that area.
  2. Hypothenar muscles: Positioned along the outer edges of the palm, these muscles govern the region opposite to the thumb, particularly around the pinkie finger.
  3. Interossei muscles: Situated between the metacarpal bones within the palm, interossei muscles facilitate side-to-side finger movements.
  4. Lumbrical muscles: Found at the base of the four non-thumb fingers, lumbrical muscles aid in flexing the fingers.

These muscles contribute to two primary types of grip:

  1. Power grip: This grip relies on the strength of the hand muscles and is utilized for tasks such as lifting heavy objects or opening jars.
  2. Precision grip: Precision grip involves the skill of the fingers and thumb to handle smaller objects. It often involves a pinching motion where the fingers meet the thumb, enabling actions like picking up a pen or turning a key in a lock.

In addition to grip, the muscles in the wrist also perform various movements:

  1. Flexion: Muscles involved in bending the wrist downward towards the palm.
  2. Extension: Muscles responsible for pulling the wrist upward, akin to making a “stop” gesture.
  3. Adduction: Muscles enable inward wrist bending towards the body’s center.
  4. Abduction: Muscles facilitate the outward turning of the wrist away from the body’s center.

Synovial Lining

This extraordinary tissue produces the synovial fluid that keeps our joints moving quickly and painlessly. Without this priceless coating, our motion would be painful and uncomfortable, and our joints would be permanently harmed.

The synovial fluid also provides essential nourishment to maintain the health and functionality of our cartilage.

The next time you walk or bend your elbow, consider how unique your synovial lining is in enabling these actions.

Volar Plates

The complex network of dense connective tissues known as the volar plates serves as vital support and stabilization for the joints in our fingers.

These unusual structures stop the fingers from bending too far backward. It can prevent serious injuries or dislocations.

The volar plates on the palmar side of the joints are made of thick, fibrous tissue. They offer a robust, solid framework to ensure appropriate alignment and integrity throughout the movement.

These plates play a crucial role in the stability and mobility of the fingers. They have a robust construction that can endure much stress and strain.

Without the volar plates, our fingers would be far more prone to injury, impairing our capacity to carry out routine activities quickly and accurately.

These complex tissues balance the firmness and flexibility necessary for hand function.

Tendon Sheaths

Tendon sheaths are one of the crucial parts of the hand anatomy that contribute to this capacity to grab an item.

The hand’s tendons are encased in these unique fluid-filled tubes, cushioning and reducing friction when the tendons pass through them.

Tendon sheaths comprise two layers of connective tissue: the inner layer is a fragile synovial membrane, and the outer layer is thick fibrous tissue.

A viscous fluid that the synovial membrane secretes lubricates the tendons, enabling them to move freely and painlessly.

This lubricant ensures the pieces work together without resistance. It is similar to the oil required to keep an automobile engine operating smoothly.

Sheaths around the tendons guide them as they pass through the hand. The sheath’s walls align the tendons, lowering the risk of damage by keeping them from rubbing against other hand structures.

Hand Anatomy Tendons

Tendons, a vital function, connect the muscles and bones of the hand. Collagen’s thick, strong, and flexible fibers make up its structure.

Tendons are essential for the complex movements needed for daily tasks like writing, typing, and even holding a cup. Without tendons, our muscles could not apply the force required to move our bones.

Interestingly, tendons are highly specialized organs that tolerate extreme tension and strain. Their unique structure enables them to expand and contract in response to our motions while being solid and sturdy.

Blood Vessels

The human hand is a unique organ that relies on a sophisticated blood artery network to supply and remove blood effectively. These blood veins provide the hand’s tissues with oxygen and nourishment. They also aid in controlling the hand’s temperature and maintaining fluid balance.

Without this complex network of blood vessels, the hand could not carry out its wide range of tasks. It’s responsible for grasping and moving items.

Therefore, the health and well-being of the hand and the body depend on the efficient operation of these blood arteries.

Nerves

The body’s nerves send and receive messages between the brain and other body parts, including the hands. These nerves enable us to sense various feelings and precisely regulate our actions.

We can perceive the environment in real-time because neurons convey messages that move through the nerves at an extraordinary speed.

Our bodily experience would be significantly diminished without nerves. We would not be able to interact with the outside world similarly.

Palmar Fascia

The palmar fascia, a tough layer of soft tissue, is found in the palm of your hand. This complex, fibrous ring of connective tissue stabilizes the palm of your hand. It serves as a solid base for the complex motions that our hands can do.

Our hands would only be as nimble with the support of the palmar fascia. We rely on it to perform various daily tasks. With it, our ability to do things is unlimited.

Fingers

The fingers play a crucial role in hand function, providing the ability to grip and manipulate objects. This capability is enabled by small bones called phalanges, which allow the fingers to flex and curl in a circular motion.

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Thumb

The thumb is particularly significant among the fingers due to its thickness and pivotal role in securely grasping objects. The thumb completes the grip when holding a pen, a paintbrush, or a weight at the gym.

In today’s digital age, where smartphone typing is ubiquitous, the importance of the thumb is further emphasized.

Index Finger

The index finger, positioned next to the thumb, aids in precise movements for tasks like writing, painting, or sculpting.

Middle Finger

The middle finger, being the longest, provides stability and strength during gripping and lifting tasks, serving as an anchor for the other fingers.

Ring Finger

Traditionally known as the ring finger, this digit is where rings, especially engagement or wedding rings, are worn. Positioned between the middle and little finger, it contributes to overall hand dexterity.

Little Finger

The little finger, or pinky finger, assists in gripping objects tightly because it is close to the palm.

Palm

With its wide, flat surface on the inner side of the hand, the palm actively participates in gripping objects—the lines on the palm aid in enhancing grip.

Wrist

The wrist, a flexible joint connecting the hand to the arm, facilitates a wide range of movements due to its multiple bones.

Knuckle

Knuckles at the back of the hand enable the fingers to move forward and backward. They are vital in combat sports like wrestling and boxing.

Fingernails

Fingernails, found at the tips of the fingers, consist of keratin, a protein also present in hair. They continue to grow indefinitely and serve various protective and functional purposes for the fingers.

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External Sources-

  • Wikipedia
  • KenHub
  • Optometrists
  • Cleveland Clinic
  • American Academy of Ophthalmology

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