How Many Bones Are in the Human Arm? (3 Bones, 32 in the Upper Limb)

Quick Answer: How many bones are in the human arm? The arm itself has 3 bones: the humerus in the upper arm and the radius and ulna in the forearm. If you count the whole upper limb, from the shoulder to the fingertips, each side has 32 bones, because the shoulder girdle adds 2 and the wrist and hand add 27.

The 3 Bones of the Arm

Bone	Location	Main Role
Humerus	Upper arm, shoulder to elbow	Longest arm bone; anchors shoulder and elbow movement
Radius	Forearm, thumb side	Rotates around the ulna to turn the palm up and down
Ulna	Forearm, little finger side	Forms the main hinge of the elbow

Keep reading for the full upper limb count, how these bones work together, and the most common arm bone injuries and conditions.

How Many Bones Are in the Whole Upper Limb?

Section	Bones	Count
Shoulder girdle	Clavicle (collarbone), scapula (shoulder blade)	2
Arm	Humerus, radius, ulna	3
Wrist	Carpal bones	8
Hand	Metacarpals	5
Fingers and thumb	Phalanges	14
Total per side		32

With both sides counted, the upper limbs hold 64 bones, nearly a third of the 206 bones in the adult human body. Most of those are packed into the hand and wrist, which is why the 27 bones covered in our guide to how many bones are in the human hand account for most of the count.

How the Arm Bones Work Together

The humerus connects to the shoulder blade at a ball-and-socket joint, which gives the shoulder the widest range of motion of any joint in the body. At the elbow, the humerus meets the ulna in a hinge joint that lets the arm bend and straighten. The radius does something unusual: it crosses over the ulna when you turn your palm down and uncrosses when you turn it up, a movement that makes actions like turning a key or a doorknob possible. At the lower end, the radius connects with the 8 bones of the wrist. The biceps and triceps attach to these bones and do much of the work, and they’re among the arm muscles covered in our look at the strongest muscle in the human body.

Common Arm Bone Injuries and Conditions

• Distal radius fracture: a break near the wrist end of the radius, one of the most common fractures, usually from falling onto an outstretched hand.
• Humerus fractures: breaks near the shoulder are common in older adults after falls, while breaks just above the elbow are common in children.
• Forearm fractures: breaks of the radius, the ulna, or both, often from falls or sports.
• Elbow dislocation: the forearm bones shift out of place at the elbow joint, usually after a fall.
• Osteoporosis: thinning bones raise the risk of fractures in the arm and wrist, especially after age 50.

Weight-bearing and strength exercise, enough calcium and vitamin D, and fall prevention all help keep arm bones strong over time. Any suspected fracture, deformity, or loss of movement should be checked by a healthcare professional.

Arm Bones vs Leg Bones

The arm and leg follow the same pattern: one bone above the elbow or knee and two below. The leg adds a kneecap, giving it 4 bones to the arm’s 3, and its bones are larger and denser because they carry the body’s weight. For the full comparison, see our guide to how many bones are in the human leg.

Frequently Asked Questions

Final Answer: How Many Bones Are in the Human Arm

The human arm has 3 bones: the humerus, radius, and ulna. Counting the shoulder girdle, wrist, and hand, each upper limb has 32 bones, or 64 for both arms. The radius near the wrist is the bone broken most often, so strength training, good nutrition, and fall prevention all play a part in keeping these bones healthy.