Complete Guide to Hand Anatomy: Parts, Names & Diagram

Overview of Hand Anatomy

The human hand is an extraordinary part of the upper limb, built for power and precision. It is necessary to feel and do 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!

This article will examine the hand’s anatomy, including its different parts and functions, to get detailed information about the hand.

Hand Anatomy 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 is an important framework of the human body. It provides structure, protection, and support to essential organs and tissues.

Among the 206 bones in the body, bones in the hands are especially important because they allow for a wide range of precise movements. These bones, joints, and muscles help grip, hold, and manipulate objects with great accuracy and control.

This strong foundation is necessary for the hand to maintain shape and stability. 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 small bones that make up our fingers and toes. There are 14 in each hand and foot. These bones get their name from Greek, meaning “finger or toe bone.”

Each finger and toe has three phalanges: proximal (closest to the hand or foot), middle, and distal (farthest from the hand or foot). However, the thumb and big toe are unique—they only have two phalanges, missing the middle one.

The distal phalanx is the bone at the tip of each finger and toe. It supports the nail and is shaped in a way that starts wide at the base, narrows, and then flares out slightly at the tip, forming a small bump.

Metacarpals

The metacarpus is made up of five long bones that connect the wrist to the fingers. These bones are numbered from 1 to 5, starting from the thumb side.

Each metacarpal has a shaft, with a broad base near the wrist and a rounded head that connects to the finger bones.

On the back of the hand, where the knuckles form, a flat, triangular area becomes visible just before the fingers.

The knuckle’s raised prominence comes from the rounded heads of the metacarpal bones, which meet the finger bones at the metacarpophalangeal joints.

The palm side of the metacarpals has concave regions where the palm muscles are positioned, providing the strength and movement needed for gripping and manipulating objects.

Carpals

The wrist contains eight small carpal bones organized into two rows supporting flexibility and strength. The first row, near the forearm, includes the scaphoid, lunate, triquetrum, and pisiform bones.

These bones form the foundation of the wrist’s connection to the arm. The second row, closer to the hand, consists of the trapezium, trapezoid, capitate, and hamate bones.

These bones are essential for smooth hand and wrist movements, supporting nearby muscles and ligaments. They also create passages for important nerves and blood vessels, contributing to the wrist’s overall function and stability.

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.

There are various types of joints, and 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, which include grasping, raising, and rotating the hand.

Carpometacarpal Joint

The carpometacarpal (CMC) joints connect the wrist to the bones of the hand to form an important link for mobility and stability. There are five CMC joints, each playing a unique role in hand movement.

The joint at the base of the thumb is the most versatile and allows for a wide range of motion, which enables actions like gripping and pinching.

The other four CMC joints, which connect the middle bones of the hand (metacarpals) to the wrist (carpal) bones, offer varying degrees of movement.

Those closer to the thumb, like at the base of the index finger, provide more flexibility, while the ones near the little finger are more rigid.

It balances strength and flexibility by helping the hand maintain stability during tasks like gripping or lifting while allowing precise movements where needed.

Hand Ligament Anatomy

Strong, flexible ligaments that provide stability and mobility support the hand and wrist. Each ligament plays a key role in maintaining the structure and proper function of the hand:

Collateral Ligaments: These are located on either side of the fingers and thumb. They prevent excessive sideways movement by keeping the digits aligned during motion.
The volar Plate is positioned on the palm side beneath the finger joints. This structure prevents the fingers from bending backward too far, protecting against hyperextension.
Palmar Fascia: A thick, triangular layer beneath the skin of the palm, this fascia helps maintain the hand’s shape during movement and prevents the skin from sliding when gripping objects.
Ulnocarpal and Radiocarpal Ligaments secure the wrist joint, allowing smooth and controlled movement between the forearm and hand.
Volar Carpal Ligaments: These are located on the underside of the wrist and provide additional support and stability during wrist movement.
Dorsal Radiocarpal Ligaments: These ligaments are positioned on the back of the wrist, stabilizing the wrist when extended and offering extra support when bending it backward.

These ligaments work together to ensure the hand remains stable and flexible, enabling precise movements to protect against injury.

Hand Muscle Anatomy

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

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.
Hypothenar muscles are positioned along the outer edges of the palm; these muscles govern the region opposite to the thumb, particularly around the pinkie finger.
Interossei muscles are situated between the metacarpal bones within the palm, and interossei muscles facilitate side-to-side finger movements.
Lumbrical muscles: This muscle is found at the base of the four non-thumb fingers; lumbrical muscles aid in flexing the fingers.

There are two main types of grip that our hand muscles help with:

Power grip: This grip uses the strength of larger hand muscles to hold or move heavy objects, like when you’re lifting weights or twisting open a tight jar lid. It’s all about force and stability.
Precision grip: This grip involves the coordination between the fingers and thumb to handle smaller, delicate objects. It usually involves a pinching motion where the fingertips meet the thumb, like when you’re picking up a coin or turning a key.

Apart from gripping, the muscles around the wrist help control different wrist movements:

Flexion: Bending the wrist towards the palm, like when you curl your hand inward.
Extension: Raising the wrist upwards, similar to making a “stop” sign with your hand.
Adduction: Moving the wrist inward toward the body’s center.
Abduction: Turning the wrist outward, away from the body’s midline.

These movements, powered by different muscle groups, allow us to perform a wide range of tasks requiring strength and precision.

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 are crucial tissues that connect muscles to bones, enabling movement in our hands. They are made mostly of collagen, a protein known for strength, flexibility, and durability.

This structure allows tendons to withstand high levels of tension and strain, which is essential for the fine motor skills we use daily, like gripping objects, writing, and typing.

What makes tendons remarkable is their ability to stretch and contract as needed while still being tough enough to handle repeated stress.

Without them, muscles wouldn’t be able to generate the force necessary to move bones, making even simple tasks impossible. Their specialized design ensures the precise and efficient movements we rely on constantly.

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.

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.

Complete Guide to Hand Anatomy: Parts, Functions & Diagram