There are about 206 bones in the human body, they have the function of
protecting and preserving the shape of soft tissues. The skeleton provides a
framework for the muscles, it controls and directs internal pressure and
provides stability anchoring points for other soft tissues. There are a wide
variety of bones/bony tissues adapted for specific functions to aid locomotion
and support, bones are moved by the skeletal
muscles. In addition
the skeletal system stores and produces blood cells in the bone marrow.
It is not the aim of this guide to catalogue each bone, but the following may
- the bones of the thorax (ribs, sternum and thoracic vertebrae) form a
cage which protects many of the body's vital organs.
- The Axial skeleton
- This is the main body including the pelvis, thorax, and skull (excluding
the arms and legs).
- The Proximal skeleton
- The femur and humerus (ie the bones proximal to the Axial skeleton)
- The Distal skeleton
- The lower legs (tibia, fibula, and feet bones) and lower arm (radius,
ulna, and bones of the hand). The Proximal and Distal skeleton are sometimes
collectively referred to as bones of the extremities.
- The spine The spine is divided into 5 main areas and each bone
(verebrae) has a letter and number.
- Cervical vetebrae C1 - C7
- the neck region. C1 is the upper most vertebrae.
- Thoracic vertabrae T1 - T12
- vertebrae of the upper body (thorax)
- Lumbar vertebrae L1 - L5
- vertebrae of the lower back
- Bones of the sacrum S1 - S5
- vertebra within the pelvic girdle. These bones fuse together between
ages 16 and 18.
- The coccyx Co1 - Co4
- The lower tip of the spine. These bones fuse together between ages
20 to 30.
Diaphysis - The long shaft of the bone.
Epiphysis - The knob like end of the bone, often contains red marrow
Metaphysis - Region where the diaphysis joins the epiphysis, important in
Medullary - Marrow cavity inside the bone. Contains yellow marrow (fat
Foramina - Tiny canals in the bone through which blood and lymph vessels
connect to the medullary.
Cartilage - Tough connective tissue covering the ends of the bone. The
cartilage reduce friction and acts as a shock absorber.
Ligament - Fibrous tissue that connects bones or cartilage to strengthen
and support joints.
The end of the bones are often refered to by the Proximal end (towards
the main body) or the Distal end (away from the main body), e.g. the
proximal femur is the top end of the thigh bone..
Compact bone - Compact bone is dense and hard, especially the outer layer
of the bone.
Spongy bone - Made up of a lattice work of bone, the spaces are filled
with red marrow which produce blood cells.
Classification of bones by shape:
Long bones - Slightly curved for STRENGTH with long narrow shafts with
knobbly ends (especially found in arms and legs e.g. femur).
Short bones - Tend to be spongy e.g. wrists, fingers, toes and ankles.
Flat bones - Plate like and highly PROTECTIVE e.g. bones of the skull
protect the brain.
Irregular bones e.g. vertebrae (spine)
Ossification is the gradual conversion of cartilage or other tissue into
bone. At birth ossification is not complete, there are still may membrane filled
spaces in the skull, these are called fontanels or "soft spots". Most bone
growth occurs during childhood, and ossification of most bones is usually
complete by age 25. The 5 bones of the sacrum fuse together from ages 18 to 25.
When all bone growth is complete the body is said to be skeletally mature.
||arthritis = inflammation of the bone
||chondrocyte = a cartilage cell.
||costalgia = pain in the ribs.
||osteosarcoma = a type of bone tumour
||curved / crooked
||scoliosis = curvature of the spine.
||osteomyelitis = inflammation of the bone
||osteoporosis = reduced bone mass-fracture prone
||thoracotomy = incision into chest/thorax
- Osteogenic Sarcoma
- Osteogenic Sarcoma (osteosarcoma) is a bone forming cancer. It is the
most frequent type of bone tumour and is most common between the ages of 15
to 25. Over 90% of tumours are located in the metaphysis (the growing ends
of the bone), the most common sites are the long bones of the legs. Most
tumours are solitary, around 2% are multifocal (2 or more bones). It is
known that osteosarcoma can be radiation induced. Osteosarcomas vary greatly
in radiological and pathological features and therefore needs careful
diagnosis to differentiate this from other bone tumours. Most are high grade
intramedullary osteosarcomas, about 5% are low grade lesions, some are
secondary osteosarcomas (for example those caused by radiation therapy).
Internet Resources for Osteosarcoma
- Ewing's Sarcoma
- Ewing's sarcoma is most common in children and young adults. The most
frequent sites are the pelvis, femur, tibia, and fibula, around a fifth of
patients have metastases at diagnosis usually in the lungs or other other
bones. Ewing's tumours are more frequently found in the diaphysis
(mid-shaft) part of the bone. Ewing's sarcoma can sometimes be restricted to
soft tissue (Extraosseos Ewing's sarcoma). There is a spectrum of pathology
ranging from 'classical' Ewing's which are negative for neural markers; to
PNET (peripheral neuroectodermal tumours) which are strongly positive.
Internet Resources for Ewing's
- Chondrosarcoma is a cancer arising in cartilage cells, it occurs mostly
in adults, it is rare in those aged under 20 with 70% of cases occurring
between ages 50-75. Rare sub-types include mesenchymal chondrosarcoma which
is more common in those aged under 40; Clear cell chondrosarcoma (around 2%
of cases); and Dedifferenting chondrosarcoma (a rare tumour which transforms
from low grade to a high grade sarcoma).
Internet Resources for
- Other Primary Bone Tumours
- Malignant Fibrous Histiocytoma (MFH) account for 10% of bone
tumours, they arise from histiocytes that have fibroblastic potential.
Chondoma is rare occurring mostly between ages 30 -70. This is a low
grade malignancy which is arises from the remnants of the notochord (cells
in the embryo which cause the formation of cartilage).
Fibrosarcoma and desmoid tumours vary in malignant potential.
Giant cell tumours some are benign, others may be malignant e.g.
giant cell osteosarcoma, giant cell fibrosarcoma.
Neurogenious tumours of bone These include neuroepithelioma and
Intraosseous liposarcoma is very rare. Liposarcoma arises from fat
cells, these tumours are common in muscle but in rare cases are found in
bone. Similarly extraosseous osteosarcoma (osteosarcoma found in soft
tissue) is very rare with less than 300 cases reported world wide.
- Bone sarcomas associated with Paget's disease
- Paget's disease is the most common bone disorder characterised by
irregular thickening and softening of the bones. The disease is more common
after the age of 40, and is frequent in those of European descent but rare
in Asians. These is an association with this (non malignant) disease and
bone cancer, up to 10% of those with Paget's disease will have a 'sarcomatous
transformation' of affected bones giving rise to bone sarcoma. This may be
osteosarcoma, fibrosarcoma, chondrosarcoma, or other bone sarcomas.
- Pathologic Fracture
- - caused by a disease, growth of the tumour may cause stress leading to
- Scintigraphy (bone scan) - e.g. used to see if a cancer has metastasised
to the bone. Primary bone cancers are relatively rare, but many other types
of cancer can metastasise to the bone.
Related Abbreviations and Acronyms:
|C1 - C7
||Cervical vertebrae (spine eg. C7 = seventh cervical vertebra)
||European Intergroup Ewing's Sarcoma Study
||European Osteosarcoma Intergroup
||Giant Cell Tumour Context: bone tumours
||Intergroup Ewing's Sarcoma Study (USA)
|L1 - L5
||Lumbar vertebrae 1 - 5 (spine eg. L1 = 1st lumbar vertebra)
||Osteogenic sarcoma (context bone tumours)
||Peripheral neuroectodermal tumour Context: Bone tumours -
see Ewing's tu
|T1 - T12
||Thoracic vertebrae 1-12 (spine eg. T10 = tenth thoracic
More Cancer Related Abbreviations