Wrist + Hands

BONES

In our hands we have a total of 27 bones, per hand. There are 8 carpal bones, 5 metacarpal bones, 5 proximal phalanges, 4 intermediate phalanges, and 5 distal phalanges. 

Bones	Info about the bone(s)	Picture
Carpals	There are 8 carpal bones in each of our wrists and their names are: Scaphoid, Lunate, Triquetrum, Pisiform, Hamate, Capitate, Trapezoid, and Trapezium. If we start at the Scaphoid bone and go counter clock wise, we can use the mnemonic “So-Long-To-Pinky Here-Comes-The-Thumb” to remember the names of each of the bones.
Metacarpals	In each hand, there are 5 metacarpal bones. Each bone includes a head, a body and a base. Metacarpal 1 is the thumb and metacarpal 5 is the pinky.
Phalanges	Each of our hands include 14 phalanges. We refer to our fingers as digits, and digit 1 is the thumb, and 5 is the pinky. Digits 2-5 include proximal, intermediate and distal phalanges, but digit 1 only includes a proximal and distal phalange.
Radius and Ulna	In our forearm, there are two bones known as the Radius and the Ulna. If you were to stand in the anatomical position, the radius would be on the lateral side of your body, and the ulna would be on the medial side of your body. These two bones meet up with our carpal bones.

LIGAMENTS

In our hands and wrists, we also have ligaments and what ligaments do is they attach bone to bone. In this specific part of the body we have intrinsic ligaments, also known as intercarpal ligaments that attach carpal bones together, and extrinsic ligaments, that attach carpal bones to the metacarpals, radius or ulna. 

3 Main ligaments located in the forearm and wrist:

Ligament	Responsibility	Picture
Radioulnar Ligaments	This ligament attaches the radius and the ulna on the distal end.
Radiocarpal Ligaments	This ligament attaches the radius to the carpal bones in the wrist.
Ulnocarpal Ligaments	This ligament attaches the ulna to the carpal bones in the wrist.

Ligaments of the hand:

Ligament	Responsibility	Picture
Intercarpal Ligaments	Intercarpal ligaments are located between the carpal bones, and attach them all with one another.
Carpometacarpal Ligaments	Carpometacarpal ligaments attach the carpal bones to the metacarpals.
Metacarpophalangeal Ligaments	Metacarpophalangeal ligaments are a type of collateral ligament, and they attach the metacarpal bones to the phalanges.
Interphalangeal Ligaments	Interphalangeal ligaments are also a type of collateral ligament. They're located in between the phalanges, since that is where the attach the phalanges together.

BONE MARKINGS

The phalanges and metacarpals in our hands are made up of a head, a body, and a base. These 3 components are considered to be the bone markings in the hand and wrist. Furthermore, where our metacarpals and phalanges articulate is where our knuckles are formed.

MUSCLES

Now lets take a look at our muscles. We have over 30 muscles in the hand and forearm alone. These muscles all work together in order for our hands to be able to move in a variety of ways. Extrinsic muscles and intrinsic muscles are the two main groups of muscles, located in the hand and forearm. 

• Extrinsic Muscles:

Flexor and extensor muscles make up the extrinsic muscles, which are responsible for large movements in the forearm on both the anterior and posterior side.

• Intrinsic Muscles:

Thenar muscles (move thumb), Hypothenar muscles (move pinky) and Interosseous muscles/ Lumbricals (move fingers) are 3 groups that make up Intrinsic muscles. Intrinsic muscles control fine movements in the hand.

Muscles	Responsibility	Picture	Picture
Thenar Muscles	Movements in the thumb are controlled by the thenar muscles. Thenar muscles oppose, abduct and flex the thumb.
Hypothenar Muscles	Movements in the pinky are controlled by the hypothenar muscles. Hypothenar muscles abduct, flex and extend the pinky.
Interosseous Muscles/ Lumbricals	Movements in the fingers are controlled by the interosseous muscles and interosseous muscles flex, abduct and adduct the fingers. Small movements that take place between the metacarpals, are controlled by the lumbricals. The lumbricals are in charge of flexion of the metacarpophalangeal (MCP) joints, and extension of the Distal Interphalangeal (DIP) and Proximal Interphalangeal (PIP) Joints.	Interosseous (Midpalmar) Muscles	Lumbricals

Major Anterior Muscles of The Forearm:

The following muscles are also known as the flexor muscles of the forearm. These muscles mainly assist in flexion.

Muscles	Responsibility	Picture
Flexor Carpi Radialis	The Flexor Carpi Radialis muscle is responsible for flexion of the wrist.
Flexor Digitorum Superficialis	The Flexor Digitorum Superficialis muscle is responsible for flexion of the phalanges.
Flexor Pollicis Longus	The Flexor Pollicis Longus muscle is responsible for opposition of the thumb.
Pronator Quadratus	The Pronator Quadratus muscle is responsible for pronating the hand.

Major Posterior Muscles of The Forearm:

The following muscles are also known as the extensor muscles of the forearm. These muscles mainly assist in extension of the wrist and phalanges.

Muscles	Responsibility	Picture
Extensor Carpi Radialis Longus	The Extensor Carpi Radialis Longus muscle is responsible for extension of the wrist.
Extensor Digitorum	The Extensor Digitorum is responsible for extension of the fingers.
Extensor Pollicis Longus	The Extensor Pollicis Longus is responsible for extension of the thumb.
Abductor Pollicis Longus	The Abductor Pollicis Longus is responsible for abduction of the thumb.

TENDONS

1. Extensor Tendons: These tendons play an important role in attaching extensor muscles to the phalanges. 
2. Flexor Tendons: These tendons are located on the palmar (volar) side of the hand, and play an important role in helping control movement in your hand.

ORIGIN AND INSERTION POINTS

All muscles in our bodies have origin and insertion points. The origin point is the fixed attachment, where the muscle attaches to a bone (sometimes another muscle) that does not move. The insertion point is the end of the muscle where it is attached to a free moving bone , also known as the bone that moves during movement.

Anterior Origins and Insertions:

• Flexor Carpi Radialis                                       Origin: Medial Epicondyle        Insertion: Metacarpal Bones
• Flexor Digitorum Superficialis                       Origin: Medial Epicondyle        Insertion: Phalanges
• Flexor Pollicis Longus                                    Origin: Radius                             Insertion: Thumb
• Pronator Quadratus                                        Origin: Ulna                                 Insertion: Radius

Posterior Origins and Insertions:

• Extensor Carpi Radialis Longus                   Origin: Humerus                         Insertion: Posterior Base of The Metacarpals
• Abductor Pollicis Longus                              Origin: Ulna & Radius                 Insertion: First Metacarpal Only
• Extensor Digitorum                                        Origin: Lateral Epicondyle         Insertion: Phalanges
• Extensor Pollicis Longus                              Origin: Ulna                                  Insertion: Distal Phalanx of The Thumb

JOINTS

6 Types of Synovial Joints:

In our bodies we have synovial joints which are known as movable joints. There are 6 types:

1. Plane (Gliding) Joints
2. Hinge Joints
3. Pivot Joints
4. Condyloid (Ellipsoid) Joints
5. Saddle Joints
6. Ball-and-Socket Joints

Joints In The Hand & Wrist:

In our hands and wrists, we have the following Joints. Stated in the brackets are what type of joint each joint is. 

• Distal Radioulnar Joint: This joint is where the Radius and Ulna articulate distally. (Pivot Joint)
• Radiocarpal Joint: This joint is where the Radius meets the carpals, and it is commonly called the wrist. (Condyloid Joint)
• Intercarpal Joints: Are located between the carpals. (Plane/Gliding Joints)
• Carpometacarpal Joints: Where the carpals and metacarpals articulate. (Plane/Gliding Joints)
• Metacarpophalangeal (MCP) Joints: Where the metacarpals and phalanges articulate. (Condyloid Joints)
• Proximal Interphalangeal (PIP) Joints: Where the proximal and intermediate phalanges articulate, in each finger. (Hinge Joints)
• Distal Interphalangeal (DIP) Joints: Where the distal and intermediate phalanges articulate with each other, in each finger. (Hinge Joints)

MOVEMENTS

Moving on to the movements which may occur within the hand and wrist, there are 12 main movements. Flexion & Extension, Hyper-extension, Adduction & Abduction, Supination & Pronation, Opposition & Reposition, Ulnar Deviation & Radial Deviation, and Circumduction.

Wrist - Specific movements that occur at the wrist are: 

• Flexion & Extension
• Supination & Pronation
• Ulnar Deviation & Radial Deviation

Fingers - Specific movements that occur within the fingers are: 

• Flexion & Extension
• Adduction & Abduction

Thumb - Specific movements that occur at the thumb are: 

• Flexion & Extension
• Adduction & Abduction
• Opposition & Reposition