Category : Anatomy

Anatomy Arteries Blood Vessels Hand

Anatomy 101: Arteries of the Arm

There are 5 arteries in the arm and shoulder that supply blood to the body.

Arteries are muscle-lined tubes in the body that transport blood from the heart to other parts of the body. In the upper extremity, there are two arteries that pass through the axilla, also known as the “armpit.” These arteries are:

  • Subclavian Artery: This is the large vessel that begins the blood supply to the upper extremity.  It begins near the heart and travels under the clavicle bone toward the shoulder.  Eventually it turns into the axillary artery.
  • Axillary Artery: This is a continuation of the subclavian artery. This artery travels deep in the arm pit, feeding muscles and bones around the shoulder with its branches. It eventually turns into the brachial artery.
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Anatomy Hand Tendons Wrist

Anatomy 101: Wrist Tendons

Tendons are fibrous cords that are similar to a rope, attached to muscles and bone. The tendons that control movement in your hands, wrists and fingers run through your forearm. There are 6 tendons that help move your wrist. The wrist tendons are:

  • Flexor carpi radialis: This tendon is one of two tendons that bend the wrist.  It attaches to the base of the second and third hand bones.  It also attaches to the trapezium, one of your wrist bones.
  • Flexor carpi ulnaris: This is the other tendon that bends the wrist. It attaches to the pisiform, another wrist bone, and to the 5th hand bone.
  • Palmaris longus tendon:  This tendon is unique because only 3/4 of the population has it. For those who do have it, it can vary in size. It is, however, a tendon you can live without because it has very little function in the hand and wrist. This tendon is often used to repair other tendons since it serves such a small purpose.
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Anatomy Finger Hand Joints

Anatomy 101: Finger Joints

Joints are cartilage surfaces that connect bones to each other. This cartilage allows our bones to glide smoothly against one another, allowing us painless movement. There are four joints in each finger, totaling 20 joints in each hand!

The small, ringer, middle and index fingers all have the same four joints:

  1. Distal Interphalangeal Joint (DIP): The DIP joint is located at the tip of the finger, just before the finger nail starts. Arthritis can develop at this joint, and it is also commonly fractured.
  2. Proximal Interphalangeal Joint (PIP): The PIP joint is the joint just below the DIP joint. It is located below the top two bones of the finger and allows the finger to bend and extend. This joint can become stiff easily after injury.
  3. Metacarpophalangeal Joint (MCP): The MP joint is where the hand bone meets the finger bone, referred to as the “knuckle.” These joints are very important, allowing us to bend/flex and spread our fingers.
  4. Carpometacarpal Joint (CMC Joint): The CMC joint is located at the bottom of the hand bone. This joint varies in each finger. For example, in the index finger, it has little motion. In the small finger, it has a lot of motion. Injuries and problems with this joint are uncommon.

The thumb joints are a little different than the other finger joints. To learn more about the thumb joints and more about the finger joints, visit our online Anatomy section.

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Anatomy Bones Shoulder

Anatomy 101: Shoulder Bones

There are five major bones in the shoulder. The shoulder bones can easily be affected by falls or accidents, in addition to arthritis. Here is an overview of the shoulder bones:

  1. Scapula: Another name for this bone is the shoulder blade. There are 17 muscles that attach to the scapula! Much of your shoulder motion is between the scapula and the chest. The scapula is part of the “shoulder girdle” which also includes muscle and ligament that allow your shoulder to move.
  2. Clavicle: This bone is also referred to as the collar bone. The clavicle connects the arm to the chest. It has joints on both ends, which can become arthritic.
  3. Acromion: This bone is a flat projection of the scapula that gives the shoulder its square shape.
  4. Coracoid Process: This bone is also a projection of the scapula. It points outward toward the front of the body. This bone is important because its muscles and ligaments help support the clavicle, shoulder joint and humerus.
  5. Glenoid Cavity: This is the socket portion of the ball-and-socket joint of the shoulder. Any abnormalities in the cavity can cause joint instability, which can lead to a condition called “frozen shoulder.”

Learn more about the shoulder bones and the anatomy of the upper extremity (including the hand, wrist, arm and shoulder) at

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Anatomy Forearm Muscles Wrist

Anatomy 101: Wrist Muscles and Forearm Muscles

The wrist muscles and forearm muscles do so much more than give you strength in your arm and wrist. These muscles also play a part in helping you move your hand and fingers. There are 18 different muscles!

Here’s a preview of these muscles:

  • Flexor pollicis longus: Helps you bend the tip of your thumb.
  • Flexor digitorum profundus: Helps you bend your index, middle, ring and small fingers.
  • Flexor digitorum superficialis: Helps you bend the middle joint of each finger, except for the thumb, which allows you to do things such as eating with chopsticks.
  • Flexor carpi ulnaris: Helps you move your wrist away from the thumb, which is helpful in playing darts.
  • Brachioradialis: Helps you twist your forearm so your palm is either facing up or down.
  • Flexor carpi radialis: Helps you bend the wrist and move it toward the thumb.
  • Palmaris longus: Helps you bend the wrist.
  • Extensor pollicis brevis: Helps you straighten the thumb.

To learn more about all 18 muscles, visit our wrist and forearm muscles page on

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Anatomy Bones Joints Wrist

Anatomy 101: Wrist Joints

The wrist joints lie between the many different bones in the wrist and forearm. Many wrist injuries (such as fractures, also known as a broken bone) involve the joint surface. There are three joints in the wrist:

  1. Radiocarpal joint: This joint is where the radius, one of the forearm bones, joins with the first row of wrist bones (scaphoid, lunate, and triquetrum).
  2. Ulnocarpal joint: This joint is where the ulna, one of the forearm bones, joins with the lunate and triquetrum wrist bones. This joint is commonly injured when you sprain your wrist. Some people are born with (or develop) an ulna that is longer than the radius, which can cause stress and pain on the joint, known as ulnocarpal abutment (impaction) syndrome.
  3. Distal radioulnar joint: This joint is where the two forearm bones connect. Pain with this joint can sometimes be a challenging problem to treat.

Learn more about the joints of the wrist and also the bones of the wrist in our Anatomy section. You can also visit for information on conditions and injuries of the hand, wrist, arm and shoulder.

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Anatomy Carpal Tunnel Syndrome Hand

Video: The Anatomy of Carpal Tunnel Syndrome

Carpal tunnel syndrome
is a common condition affecting the hands. Patients typically say that they wake up at night with a feeling of pins and needles in their fingers, like their hand is asleep. They commonly shake their hands out to relive the symptoms. As the problem progresses, their hands will go numb when they drive, talk on the phone, or do their hair. As the problem becomes more severe, they will eventually report constant numbness in their fingers.

All of the nerves that go to the hand originate from the spinal cord at the neck level. The median nerve goes down the arm and crosses the wrist under a ligament called the transverse carpal ligament. This nerve then gives sensation to the thumb, index and long finger, as well as half the ring finger. Watch this 2-minute animation to learn more about how carpal tunnel affects your hand.

You can also read more about carpal tunnel on our website,

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Anatomy Arteries Hand

Anatomy 101: Arteries of the Hand

Arteries of the Hand

Arteries are multi-layered tubes that take blood from the heart to other places in the body. There are six arteries that travel into the hand. They are:

Deep Palmar Arch
Named for its shape of an arch, the deep palmar arch is small but important. This vessel sends off small branches to supply blood to the thumb and index finger.

Superficial Palmar Arch
Also named for its shape of an arch, this vessel communicates with the deep palmar arch and also gives off important branches that supply blood to the fingers.  These are called the common digital arteries.

Common Digital Arteries
The common digital arteries are small vessels that come from the palmar arches and supply blood to the fingers.  They are called “common” because when they split to become the proper digital arteries, most of these vessels provide blood to two different fingers.

Digital Arteries to the Thumb
The thumb receives its blood supply from the digital arteries.

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