How are the hand and wrist structured?
Your hand and wrist are structured to allow you to move, flex and rotate your wrist joint and to use your hand to grab and touch objects.
Your wrist acts like a pivot point that can move in almost any direction as you reach and flex your hand. Think about your hand and wrist like a crane game at an arcade. Your hand is the claw that grabs and holds prizes, and your wrist is the mechanical joint that lets the claw move up and down, and side to side.
Hand and wrist anatomy
The parts that make up your hand and wrist are layered upon each other to form a three-dimensional shape that gives them the ability to move and function.
Your hand and wrist are made of:
Bones.
Muscles.
Nerves.
Tendons.
Ligaments.
Blood vessels (arteries and veins).
Lymphatic vessels.
Hand and wrist bones
Bones provide the main structural support in your hand and wrist. They give them their shape and are the anchors other pieces are connected to.
Hand bones
There are 19 bones in each of your hands. They’re grouped together by their location and function:
Metacarpals: The bones that are in your palm and give it its shape.
Phalanges: The individual bones that make up the segments of your fingers and thumb.
Sesamoids: Small bones embedded in your tendons that help them move smoothly.
Wrist bones
Your wrist is a complex joint made of eight bones that are arranged into two rows.
The proximal row (on the back of your hand, closest to your forearm) includes the:
Scaphoid.
Lunate.
Triquetrum.
Pisiform.
The distal row (on the underside of your wrist closest to your palm) includes the:
Trapezium.
Trapezoid.
Capitate.
Hamate.
Your radius (the larger of the two bones in your forearm) forms a joint your scaphoid and lunate bones to form the part of your wrist that helps it move and rotate.
The carpal tunnel is a rounded space between your pisiform, hamate, scaphoid and trapezium. This space is a literal tunnel in your wrist that lets nine tendons, four ligaments and one nerve pass through it to reach the rest of your hand.
Your carpal tunnel is similar to the way that fiber optic cables are buried underground to deliver internet or cable TV service to your home.
Hand and wrist muscles
Muscles are soft tissue made of stretchy fiber. Intrinsic muscles inside your hand work with extrinsic muscles near the outside of your hand and in your forearm to give your hand its strength and dexterity.
Hand muscles
There are 34 muscles in each of your hands. Healthcare providers categorize them into groups, including:
Thenar muscles: Muscles that control your thumb. You can feel them bulge at the base of your thumb in the palm of your hand.
