List Of Bones Of The Human Skeleton - Bones In The Human Body

The skeleton of an adult human consists of 206 bones. It is composed of 270 bones at birth, which decreases to 206 bones by adulthood after some bones have fused together. It consists of 80 bones in the axial skeleton (28 in the skull and 52 in the torso) and 126 bones in the appendicular skeleton (32 × 2 in the upper extremities including both arms and 31 × 2 in the lower extremities including both legs). Many small and often variable bones, such as some sesamoid bones, are not included in this count.

Introduction

The number of bones in the skeleton changes with age, as multiple bones fuse, a process which typically reaches completion in the third decade of life. In addition, the bones of the skull and face are counted as separate bones, despite being fused naturally. Some reliable sesamoid bones such as the pisiform are counted, while others, such as the hallux sesamoids, are not.

Individuals may have more or fewer bones than this owing to anatomical variations. The most common variations include sutural (wormian) bones, which are located along the sutural lines on the back of the skull, and sesamoid bones which develop within some tendons, mainly in the hands and feet. Some individuals may also have additional (i.e. supernumerary) cervical ribs or lumbar vertebrae.

Bones

Spine (vertebral column)

A fully grown adult features 26 bones in the spine, whereas a child can have 34.

• The cervical vertebrae (7)
• The thoracic vertebrae (12)
• The lumbar vertebrae (5)
• The sacral vertebrae (5 at birth, later fused into one)
• The coccygeal vertebrae (5 at birth, some or all of the bones fuse together but there seems to be a disagreement between researchers as to what the most common number should be. Some say the most common is 1, others say 2 or 3, with 4 being the least likely. It is counted as 1 in this article.)

Chest (thorax)

There are usually 25 bones in the chest but sometimes there can be additional cervical ribs in humans. Cervical ribs occur naturally in other animals such as reptiles.

• The sternum (1)
• The ribs (24, in 12 pairs)
  • It is important to note that three pairs (the 8th, 9th and 10th), also known as false ribs, are attached to each other. They are also attached to the 7th rib by cartilage and synovial joints. Also two pairs of floating ribs (the 11th and 12th), have no anterior attachment.
  • Cervical ribs are extra ribs that occur in some humans.

Skull (cranium)

There are 22 bones in the skull. Including the hyoid and the bones of the middle ear, the head contains 29 bones.

• The cranial bones (8)
  • The occipital bone
  • The parietal bones (2)
  • The frontal bone
  • The temporal bones (2)
  • The sphenoid bone (sometimes counted as facial)
  • The ethmoid bone (sometimes counted as facial)
• The facial bones (14)
  • The nasal bones (2)
  • The maxillae (upper jaw) (2)
  • The lacrimal bone (2)
  • The zygomatic bone or cheekbone (2);
  • The palatine bone (2)
  • The inferior nasal concha (2)
  • The vomer
  • The mandible (lower jaw)
• The hyoid bone (not connected to any other bone)
• In the middle ears (6)
  • malleus (2)
  • incus (2)
  • stapes (2)

Arm

There are a total of 64 bones in the arm.

• The upper arm bones (6 bones, 3 on each side)
  • The humerus
  • The shoulder (pectoral girdle)
    • The scapula
    • The clavicles
• The lower arm bones (4 bones, 2 on each side)
  • The ulna
  • The radius
• The hand (54 bones, 27 in each hand)
  • The carpals
    • scaphoid bone (2)
    • lunate bone (2)
    • triquetral bone (2)
    • pisiform bone (2)
    • trapezium (2)
    • trapezoid bone (2)
    • capitate bone (2)
    • hamate bone (2)
  • The metacarpals (5 × 2 = 10)
  • The phalanges of the hand
    • proximal phalanges (5 × 2 = 10)
    • intermediate phalanges (4 × 2 = 8)
    • distal phalanges (5 × 2 = 10)

Pelvis (pelvic girdle)

The hip bone has three regions: ilium, ischium, and pubis (2)

• The sacrum and the coccyx attach to the two hip bones to form the pelvis, but are more important to the spinal column. For this reason it is omitted from the pelvic girdle.

Leg

• The femur (2)
• The patella or kneecap (2)
• The tibia (2)
• The fibula (2)
• The foot (52 bones in total, 26 per foot)
  • The tarsus
    • calcaneus or heel bone (2)
    • talus (2)
    • navicular bone (2)
    • medial cuneiform bone (2)
    • intermediate cuneiform bone (2)
    • lateral cuneiform bone (2)
    • cuboid bone (2)
  • The metatarsals (10)
  • The phalanges of the foot
    • proximal phalanges (5 × 2 = 10)
    • intermediate phalanges (4 x 2 = 8)
    • distal phalanges (5 x 2 = 10)

Sesamoid bones

• Patella
• Pisiform bone
• Fabella
• Cyamella (bone)
• Sesamoids in the first and second metacarpal bones
• Sesamoids in the first metatarsal bone
• Inconsistent sesamoids in other fingers and toes
• Lenticular process of the incus
• Rider's bone
• Inconsistent sesamoids in the legs, arms or buttocks

References

• The 206 Bones of the Human Body