Bones in the Human Body

by Dinesh 2012-08-29 18:18:55

Bones in the Human Body:

The number of bones in human body at birth is 300. However, as a child grows, some of the bones fuse. This makes one wonder how many bones does the human body have? As a child grows, the number of bones in his body keeps reducing. The result is that there are 206 bones in the body of an adult human being. This difference in the number of bones helps forensic anthropologists in determining the age of an individual through the skeletal remains, mainly the skull. The various bones form the skeletal system. Their main function is to provide for the framework of the human body and to protect its delicate organs.

  • Frontal Bone:
  • This bone forms the forehead.

  • Parietal Bones:
  • One bone from each side joins behind the frontal bone to form the sides and the roof of the cranium. There are 2 parietal bones in all.

  • Temporal Bones:
  • There are 2 temporal bones in all, one on each side below the parietal bones.

  • Occipital Bone:
  • This is a single bone that is present at the back of the cranium just behind the parietal and temporal bones.

  • Sphenoid Bone:
  • This is a single bone that is situated at the base of the skull in front of the temporal bones and basilar part of the occipital bone.

  • Ethmoid Bone:
  • This is a light and spongy bone that is situated in the anterior part of the base of the cranium. It lies between the two orbits at the roof of the nasal cavity separating the brain from the nasal cavity.

  • Mandible:
  • This is the lower jawbone. It is U shaped and the largest and strongest bone of the face. The mandible consists of two halves that fuse at the mental symphysis by the age of two years. Each half of the mandible has a horizontal body and a vertical ramus at the posterior end of the body.

  • Maxilla:
  • The maxilla contributes to the roof of the oral cavity and the lateral walls and floor of the nasal cavity. It also provides for the attachment of the teeth of the upper jaw. It is actually two bones that are fused along the palatal fissure.

  • Zygomatic Bone:
  • There are 2 zygomatic bones one on each side of the face forming the prominence of the cheek. Each bone also forms a part of the lateral side and floor of each orbit.

  • Palatine Bone:
  • The palatine is an L shaped bone that is situated between the maxilla and the pterygoid process of the sphenoid. It is located behind the nasal cavity and hence, contributes to its floor and the lateral walls. Besides the nasal cavity, it also contributes to the roof of the mouth as well as to the floor of the orbit.

  • Vomer:
  • It is a thin, flat single bone that lies along the mid sagittal line. It articulates with the ethmoid, the sphenoid, the two palatine and two maxillary bones each (that is 6 bones in all).

  • Lacrimal Bone:
  • There are 2 lacrimal bones in all, each lying in the frontal part of the medial wall of the orbit. These are the smallest bones of the face and each interacts with the frontal bone, the ethmoid bone, the maxilla and the inferior nasal concha.

  • Nasal Bones:
  • These are 2 oblong bones placed side to side that form the bridge of the nose.

  • Inferior Nasal Concha:
  • These are paired bones of the face that arise from the maxillary bone and continues horizontally along the lateral wall of the nasal cavity. (Ahead of these bones are the middle and the superior nasal conche that are considered to be part of the cranium).

  • Cervical Vertebrae:
  • The cervical vertebrae are the first 7 vertebrae that are also the smallest of the true vertebrae. They are different from those in the thoracic and lumbar regions in the fact that they have a hole or foramen in each transverse process for the vertebral process to pass through. The skull is supported on the first cervical vertebra which is known as the atlas. The second cervical vertebra is the axis which forms the pivot on which the atlas carrying the skull turns. The cervical vertebrae form the neck.

  • Thoracic Vertebrae:
  • There are 12 vertebrae in all in the thoracic region that come right after the cervical vertebrae. These are larger than the cervical vertebrae but smaller than those in the lumbar region. The distinct features of these vertebrae are the presence of facets that provide for the attachment of ribs. Each thoracic vertebra has facets on the side of the bodies where heads of the ribs attach. Other than the last two vertebrae, all the rest of the ten vertebrae have one facet on each of the transverse process for articulation with tubercles of the ribs.

  • Lumbar Vertebrae:
  • The lumbar vertebrae consists of 5 vertebrae. They lack the foramen on transverse process that the cervical vertebrae have and the facets on the body that characterize the thoracic vertebrae.

  • Sacral Vertebrae:
  • 5 sacral vertebrae fuse to form a triangular bone called the sacrum in adults. The sacrum fits between the two hip bones and joins the spine and the pelvis together.

  • Coccyx:
  • The coccyx consists of 4 bones that fuse together as one grows up. Coccyx can variably consist of 5 or 3 bones as well.

  • Scapula:
  • The scapula is a flat triangular bone that forms the posterior part of the shoulder girdle. It connects the humerus (upper arm) with the clavicle. It is what we commonly refer to as the shoulder blade that provides for the attachment of the humerus. There are two shoulder blades, one on each side of the body.

  • Clavicle:
  • It is commonly called the collarbone. It is a pair of small curved bones that join the scapula and hence, the humerus to the sternum. Together the clavicle and the scapula form the shoulder girdle.

  • Sternum:
  • This is a long T-shaped bone. It lies in the front, central portion of the rib cage or the chest and provides for the ribs and the clavicle to attach. It consists of three parts. The topmost part is the manubrium to which the clavicle attaches. This is followed by the body (to which the ribs attach). The end portion of the sternum is the xyphoid process.

  • Ribs:
  • There are 12 pairs of ribs in all. The first seven pairs are directly attached to the sternum through cartilage. The next three are attached to the sternum through a common cartilaginous extension. The last two pairs are known as the floating ribs because although they start from the thoracic vertebrae, they do not attach to the sternum.

  • Humerus:
  • This is a single long bone of the upper arm. It runs from the shoulder to the elbow. The humerus connects the scapula to the bones of the forearm.

  • Radius:
  • Radius is one of the bones of the forearm that lies on the lateral side of the ulna (the other bone of the forearm). It starts from the lateral side of the elbow and continues to the thumb side of the wrist.

  • Ulna:
  • This bone runs parallel to the radius along the forearm. It lies on the medial side of the body.

  • Carpal Bones:
  • These are the bones of the wrist. There 7 carpal bones in each wrist. They are

    Scaphoid bones
    Lunate bones
    Triquetral bone
    Pisiform bone
    Trapezoid bone
    Capitate bone
    Hamate bone

  • Metacarpal Bones :
  • These are the bones of the palms and there are 5 metacarpal bones in every palm, one corresponding to each digit.

  • Phalanges:
  • These are the bones of the fingers. There are 5 proximal phalanges in each hand that lie in front of the metacarpals. They are 4 intermediate phalanges in front of the proximal phalanges, one on each finger other than the thumb. The last phalanges at the tip of each finger are known as the distal phalanges. They are 5 in number.

  • Femur:
  • This is the longest bone in the human body. It is also known as the thigh bone. The head forms the ball and socket joint at the pelvic girdle.

  • Tibia:
  • The tibia is the second longest bone in the human body. Along with the fibula, it forms the lower part of the leg below the knee. It articulates with the femur at its superior end and with the talus at its inferior end. Laterally it articulates with the fibula. The tibia is considered by many to be the strongest bone of the body. It is commonly known as the shin bone.

  • Fibula:
  • The fibula is a long but thin bone that along with the tibia forms the lower part of the human leg. It is attached to the tibia at both the ends. Its upper end articulates with the tibia at the back of its head whereas while attaching to the tibia with its lower end, it angles slightly forward. The fibula is also known as the calf bone.

  • Patella:
  • One on each leg, the patella is the knee cap. It is a triangular bone that forms a protective cap over the knee joint.

  • Tarsal Bones:
  • There are 7 tarsal bones in all that lie between the tibia-fibula and the metatarsals. They are,

    Calneus (heel bone)
    Navicular bone
    Medial cuneiform bone
    Intermediate cuneiform bone
    Lateral cuneiform bone
    Cuboid bone

  • Metatarsal Bones:
  • There are 5 metatarsal bones in each foot, one corresponding to each digit. These lie between the tarsal bones and the phalanges. These may be considered to be equivalent to the metacarpal bones of the hands.

  • Phalanges:
  • These are bones of the toes of the feet. There are 5 proximal phalanges in each foot that start from the metatarsals. There are 4 intermediate phalanges, one on each finger other than the big toe. The last phalanges at which each toe ends are known as the distal phalanges. They are 5 in number.

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