Bones support and protect vital organs of the body and is dynamic (constantly changing)

Bones provide anchoring attachments for the skeletal muscles. These muscles then move the bones to allow body movement.

Osteology is the study of bones.

Orthopedics deals with traumatic musculoskeletal injuries (not just broken bones). The name comes from its history—it was established as a means of correcting deformities in children.

Sesamoid bone

Sesamoid bones

Patella is a sesamoid bone that develops over time

Locations where cartilage is found

Cartilage helps support structures in the respiratory tract.

Cartilage provides a gliding surface at articulations (joints) were two bones meet.

Cartilage can serve as model for later bone development.

Hyaline cartilage contributes to the structures of the respiratory tract, fetal skeleton, growth plates, and joints.

Close-up view of fibrocartilage

Elastic cartilage

WHICH OF THE FOLLOWING IS CORRECT ABOUT CARTILAGE?

A IS USED TO MAKE FINGERNAILS

B IS FOUND IN THE PERITONEAL CAVITY

C IS FOUND IN THE MEDIASTINUM

D IS FOUND IN THE DORSAL BODY CAVITY

E ALL OF THE ABOVE

Each bone is an organ because it contains numerous types of tissue, including vascular, nervous, connective, muscular, cartilage, and osseous.

Bones allow movement by acting as levers

Hematopoiesis (hemopoiesis) occurs within the active (red) marrow of the adult sternum, vertebrae, pelvis (ossa coxae), and proximal ends of bones of thigh and upper arm.

Hematopoiesis in an adult occurs in the red marrow of the skull, sternum, vertebrae, pelvis (ossa coxae), and proximal epiphyses of the thigh bones and upper arm bones.

I am not a big fan of sternal bone marrow biopsies.

Posterior portion of the ilium is better

Method of bone marrow biopsy utilizing the posterior pelvis (ossa coxae)

Bones are mineral storage deposits for calcium, phosphate, magnesium, and sodium salts. Withdrawals and deposits are constant.

• 90-95% of your calcium and phosphorous stored in bones, as well as magnesium and sodium salts

• Minerals give bone its strength

• Minerals are needed for blood clotting, muscle contraction, ATP synthesis, etc.

Yellow marrow is inactive and is found in the central shaft. Red marrow is active and is found in the spongy bone at the proximal ends of long bones of arm and thigh, etc.

Osso bucco anyone?

Bones vary in shape and size

Shapes of Bones

The central shaft of a long bone is called the diaphysis

The ends of a long bone are called the epiphyses

Each epiphysis is covered with smooth, slippery hyaline cartilage. Note nutrient

foramen that allows passage of blood vessels to keep bone alive.

Pulling stress on the periosteum causes and increase in bone width.

The epiphyseal growth plate allows long bones to increase in length.

Hyaline cartilage

Human growth hormone, produced by the anterior portion of the pituitary, stimulates the mitotic activity of the epiphyseal growth plate.

Fracture through epiphyseal growth plate. This can lead to premature ossification

Eventually the epiphyseal growth plate ossifies and is replaced with an epiphyseal line

Osteoblasts secrete osteoid, which later becomes bone

Osteoclasts break down bone

Osteoclast in action breaking down bone

osteocytes

Structurally unstable bones of the skull.

Read about Paget disease of bone (osteitis deformans) in the clinical view in the text.

Ilizarov apparatus

WHICH OF THE FOLLOWING IS FALSE ABOUT LONG BONES?

A THEY ARE FOUND IN THE CRURAL REGION

B THE DIAPHYSIS IS SURROUNDED BY THE EPIPHYSES

C THEY MAY BE ELONGATED WITH AN ILLIZAROV DEVICE

D THEY ARE DERIVED FROM A CARTILAGE MODEL

E THEY ARE INVOLVED IN HEMOPOIESIS IN INFANTS, BUT NOT IN ADULTS

Cross-section through long bone showing medullary cavity

Bone consists of organic components (cells, collagen fibers, and ground substance) and inorganic components (calcium compounds, phosphorus, sodium, magnesium, sulfate, and fluoride).

Bone can be organized as either spongy (cancellous) bone or as compact (dense) bone.

Compact bone

Spongy bone

The spongy bone found between the layers of compact bone in the skull is called diploë

If only the outer compact bone is broken, the inner layer of compact bone will still protect the brain.

Intramembranous ossification (shown in gold) leads to formation of flat bones of skull, zygomatic (cheek) bone, maxilla (upper jaw), mandible (lower jaw), collar bone (clavicle), and sesamoid bones.

Most bones develop by endochondral ossification (red areas). The gray areas show bones developing by intramembranous ossification.

x

Start of endochondral ossification

Continuation of endochondral ossification

A growing child

A growing adolescent

An adult

Finger bones of a juvenile bat

Finger bones of an adult bat

Read about forensic anthropology in the clinical view in your text

Read about achondroplastic dwarfism in the clinical view in your text.

Pulling stress on the periosteum stimulates osteoblasts which causes bones to increase in width.

Remains of victims of Pompeii after overlying ash is removed

How could anthropologists distinguish Roman soldiers basedsolely on their arm bones?

Osteoclasts dissolve bone tissue adjacent to the medullary cavity so this cavity maintains an appropriate size for the increase in bone growth

Dental braces can cause remodeling of the surrounding bone by increasing the activity of osteoclasts and osteoblasts.

Traction (Ilizarov method is shown) can also stimulate osteoblasts to fill in gaps in long bones.

Blood vessels bring oxygen and nutrients to the metabolically-active bone cells. Nerves also enter the bone and can signal injuries to the bone.

Hormones produced by several glands can directly, or indirectly, influence bone growth.

Vitamin A stimulates osteoblasts, Vitamin C is needed to synthesize collagen, and Vitamin D aides in the intestinal absorption of calcium and phosphate.

Read about rickets in the clinical view in your text.

Paralyzed persons, such as Christopher Reeve, suffer loss of bone mass and weakened bones because of lack of pulling stress on the periosteum.

Astronauts suffer loss of bone mass and weakened bones because lack of pulling stress on the periosteum.

NASA just sent up a $5 million treadmill named the COLBERT (after the comedian Stephen Colbert)

Bears show very little bone loss during hibernation—if we could figure out how they do that it could really help astronauts and also bedridden patients.

Read about how bone scans can reveal the health of bones in the clinical view in your text.

A fracture is a cracking of the bone. This is a view of a broken bone as viewed in an X-ray image.

The discoverer of X-rays.

X-rays are used by radiologists to diagnose bone fractures and many other problems inside the body.

Most bone fractures are the result of traumatic injury

Closed fracture of the tibia after fall on trampoline

Open fracture of the femur. Open fractures of the femur, or even closed fractures of the femur, can be associated with life-threatening blood loss.

Greenstick fractures are almost exclusively limited to children since their bones are not completely ossified.

Greenstick fracture of the fibula. Note also the epiphyseal growth plates.

Depressed skull fracture

Displaced fracture of the head of the humerus

Nondisplaced spiral fracture of the tibia. Note also the epiphyseal growth plates. This child jumped off the kitchen counter while spinning and then planted her foot on the linoleum floor.

Fractures heal best when the bones are returned to proper anatomical position and then immobilized in place.

Immobilization may involve plates and screws in addition to a cast.

• If you have a cast, be sure it matches your style!

Sequence of events in healing following a bone fracture

Distinctive bone markings or surface features

Surface features of bone

Surface features of bone

Crest

Process

Spine

Tubercle & Tuberosity

Trochanter

Surface features of bone

Aging causes bones to become more brittle and they tend to demineralize resulting in insufficient ossification (osteopenia). Aging causes all persons to become slightly osteopenic.

Read about osteoporosis in the clinical view in your text