6.3 Bone Structure – Anatomy & Physiology (2024)

Learning Objectives

By the end of this section, you will be able to:

Describe the microscopic and gross anatomical structures of bones

  • Identify the gross anatomical features of a bone
  • Describe the histology of bone tissue, including the function of bone cells and matrix
  • Compare and contrast compact and spongy bone
  • Identify the structures that compose compact and spongy bone
  • Describe how bones are nourished and innervated
  • function?

Bone tissue (osseous tissue) differs greatly from other tissues in the body. Bone is hard and many of its functions depend on that characteristic hardness. Later discussions in this chapter will show that bone is also dynamic in that its shape adjusts to accommodate stresses. This section will examine the gross anatomy of bone first and then move on to its histology.

A long bone has two main regions: the diaphysis and the epiphysis (Figure 6.3.1). The diaphysis is the hollow, tubular shaft that runs between the proximal and distal ends of the bone. Inside the diaphysis is the medullary cavity, which is filled with yellow bone marrow in an adult. The outer walls of the diaphysis (cortex, cortical bone)are composed of dense and hard compact bone, a form of osseous tissue.

6.3 Bone Structure – Anatomy & Physiology (1)

The wider section at each end of the bone is called the epiphysis (plural = epiphyses), which is filled internally with spongy bone, another type of osseous tissue. Red bone marrow fills the spaces between the spongy bone in some long bones. Each epiphysis meets the diaphysis at the metaphysis.During growth, the metaphysis contains the epiphyseal plate, thesite of long bone elongation described later in the chapter.When the bone stops growing in early adulthood (approximately 18–21 years), the epiphyseal plate becomes an epiphyseal line seen in the figure.

Lining the inside of the bone adjacent to the medullary cavity is a layer of bone cells called the endosteum (endo- = “inside”; osteo- = “bone”). These bone cells (described later) cause the bone to grow, repair, and remodel throughout life. On the outside of bones there is another layer of cells that grow, repair and remodel bone as well. These cells are part of the outer double layered structure called the periosteum (peri– = “around” or “surrounding”). The cellular layer is adjacent to the cortical bone and is covered by an outer fibrous layer of dense irregular connective tissue (see Figure 6.3.4a). The periosteum also contains blood vessels, nerves, and lymphatic vessels that nourish compact bone. Tendons and ligaments attach to bones at the periosteum. The periosteum covers the entire outer surface except where the epiphyses meet other bones to form joints (Figure 6.3.2). In this region, the epiphyses are covered with articular cartilage, a thin layer of hyaline cartilage that reduces friction and acts as a shock absorber.

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Flat bones, like those of the cranium, consist of a layer of diploë (spongy bone), covered on either side by a layer of compact bone (Figure 6.3.3). The two layers of compact bone and the interior spongy bone work together to protect the internal organs. If the outer layer of a cranial bone fractures, the brain is still protected by the intact inner layer.

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Bone Matrix
Osseous tissue is a connective tissue and like all connective tissues contains relatively few cells and large amounts of extracellular matrix. By mass, osseous tissue matrix consists of 1/3rd collagen fibers and 2/3rds calcium phosphate salt. The collagen provides a scaffolding surface for inorganic salt crystals to adhere (see Figure 6.3.4a). These salt crystals form when calcium phosphate and calcium carbonate combine to create hydroxyapatite. Hydroxyapatite also incorporates other inorganic salts like magnesium hydroxide, fluoride, and sulfate as it crystallizes, or calcifies, on the collagen fibers. The hydroxyapatite crystals give bones their hardness and strength, while the collagen fibers give them a framework for calcification and gives the bone flexibility so that it can bend without being brittle. For example, if you removed all the organic matrix (collagen) from a bone, it would crumble and shatter readily (see Figure 6.3.4b, upper panel). Conversely, if you remove all the inorganic matrix (minerals) from bone and leave the collagen, the bone becomes overly flexible and cannot bear weight (see Figure 6.3.4b, lower panel).
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Bone Cells

Although bone cells compose less than 2%of the bone mass, they are crucial to the function of bones. Four types of cells are found within bone tissue: osteoblasts, osteocytes, osteogenic cells, and osteoclasts (Figure 6.3.5).

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The osteoblast is the bone cell responsible for forming new bone and is found in the growing portions of bone, including theendosteum and the cellular layer of the periosteum. Osteoblasts, which do not divide, synthesize and secrete the collagen matrix and other proteins. As the secreted matrix surrounding the osteoblast calcifies, the osteoblast become trapped within it; as a result, it changes in structure and becomes an osteocyte, the primary cell of mature bone and the most common type of bone cell. Each osteocyte is located in a small cavity in the bone tissue called a lacuna (lacunae for plural).Osteocytes maintain the mineral concentration of the matrix via the secretion of enzymes. Like osteoblasts, osteocytes lack mitotic activity. They can communicate with each other and receive nutrients via long cytoplasmic processes that extend through canaliculi (singular = canaliculus), channels within the bone matrix. Osteocytes are connected to one another within the canaliculi via gap junctions.

If osteoblasts and osteocytes are incapable of mitosis, then how are they replenished when old ones die? The answer lies in the properties of a third category of bone cells—the osteogenic (osteoprogenitor) cell. These osteogenic cells are undifferentiated with high mitotic activity and they are the only bone cells that divide. Immature osteogenic cells are found in the cellularlayer of the periosteum and the endosteum. They differentiate and develop into osteoblasts.

The dynamic nature of bone means that new tissue is constantly formed, and old, injured, or unnecessary bone is dissolved for repair or for calcium release. The cells responsible for bone resorption, or breakdown, are the osteoclasts. These multinucleated cells originate from monocytes and macrophages, two types of white blood cells, not from osteogenic cells. Osteoclasts are continually breaking down old bone while osteoblasts are continually forming new bone. The ongoing balance between osteoblasts and osteoclasts is responsible for the constant but subtle reshaping of bone. Table 6.3 reviews the bone cells, their functions, and locations.

Bone Cells (Table 6.3)
Cell typeFunctionLocation
Osteogenic cellsDevelop into osteoblastsEndosteum, cellular layer of the periosteum
OsteoblastsBone formationEndosteum, cellular layer of the periosteum, growing portions of bone
OsteocytesMaintain mineral concentration of matrixEntrapped in matrix
OsteoclastsBone resorptionEndosteum, cellular layer of the periosteum, at sites of old, injured, or unneeded bone

Most bones contain compact and spongy osseous tissue, but their distribution and concentration vary based on the bone’s overall function. Although compact and spongy bone are made of the same matrix materials and cells, they are different in how they are organized. Compact bone is dense so that it can withstand compressive forces, while spongy bone (also called cancellous bone) has open spaces and is supportive, but also lightweight and can be readily remodeled to accommodate changing body needs.

Compact Bone

Compact bone is the denser, stronger of the two types of osseous tissue (Figure 6.3.6). It makes up the outer cortex of all bones and is in immediate contact with the periosteum. In long bones, as you move from the outer cortical compact bone to the inner medullary cavity, the bone transitions to spongy bone.

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If you look at compact bone under the microscope, you will observe a highly organized arrangement of concentric circles that look like tree trunks. Each group of concentric circles (each “tree”) makes up the microscopic structural unit of compact bone called an osteon (this is also called aHaversian system). Each ring of the osteon is made of collagen and calcified matrix and is called a lamella (plural = lamellae). The collagen fibers of adjacent lamallae run at perpendicular angles to each other, allowing osteons to resist twisting forces in multiple directions (see figure 6.34a). Running down the center of each osteon is the central canal, or Haversian canal, which contains blood vessels, nerves, and lymphatic vessels. These vessels and nerves branch off at right angles through a perforating canal, also known as Volkmann’s canals, to extend to the periosteum and endosteum. The endosteum also lines each central canal, allowing osteons to be removed, remodeled and rebuilt over time.

The osteocytes are trapped within their lacuane, found at the borders of adjacent lamellae. As described earlier, canaliculi connect with the canaliculi of other lacunae and eventually with the central canal. This system allows nutrients to be transported to the osteocytes and wastes to be removed from them despite the impervious calcified matrix.

Spongy (Cancellous) Bone

Like compact bone, spongy bone, also known as cancellous bone, contains osteocytes housed in lacunae, but they are not arranged in concentric circles. Instead, the lacunae and osteocytes are found in a lattice-like network of matrix spikes called trabeculae (singular = trabecula) (Figure 6.3.8). The trabeculae are covered by the endosteum, which can readily remodel them. The trabeculae may appear to be a random network, but each trabecula forms along lines of stress to direct forces out to the more solid compact bone providingstrength to the bone. Spongy bone provides balance to the dense and heavy compact bone by making bones lighter so that muscles can move them more easily. In addition, the spaces in some spongy bones contain red bone marrow, protected by the trabeculae, where hematopoiesis occurs.

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Aging and the…Skeletal System: Paget’s Disease

Paget’s disease usually occurs in adults over age 40. It is a disorder of the bone remodeling process that begins with overactive osteoclasts. This means more bone is resorbed than is laid down. The osteoblasts try to compensate but the new bone they lay down is weak and brittle and therefore prone to fracture.

While some people with Paget’s disease have no symptoms, others experience pain, bone fractures, and bone deformities (Figure 6.3.9). Bones of the pelvis, skull, spine, and legs are the most commonly affected. When occurring in the skull, Paget’s disease can cause headaches and hearing loss.

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What causes the osteoclasts to become overactive? The answer is still unknown, but hereditary factors seem to play a role. Some scientists believe Paget’s disease is due to an as-yet-unidentified virus.

Paget’s disease is diagnosed via imaging studies and lab tests. X-rays may show bone deformities or areas of bone resorption. Bone scans are also useful. In these studies, a dye containing a radioactive ion is injected into the body. Areas of bone resorption have an affinity for the ion, so they will light up on the scan if the ions are absorbed. In addition, blood levels of an enzyme called alkaline phosphatase are typically elevated in people with Paget’s disease. Bisphosphonates, drugs that decrease the activity of osteoclasts, are often used in the treatment of Paget’s disease.

The spongy bone and medullary cavity receive nourishment from arteries that pass through the compact bone. The arteries enter through the nutrient foramen (plural = foramina), small openings in the diaphysis (Figure 6.3.10). The osteocytes in spongy bone are nourished by blood vessels of the periosteum that penetrate spongy bone and blood that circulates in the marrow cavities. As the blood passes through the marrow cavities, it is collected by veins, which then pass out of the bone through the foramina.

In addition to the blood vessels, nerves follow the same paths into the bone where they tend to concentrate in the more metabolically active regions of the bone. The nerves sense pain, and it appears the nerves also play roles in regulating blood supplies and in bone growth, hence their concentrations in metabolically active sites of the bone.

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External Website

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Watch this video to see the microscopic features of a bone.

Chapter Review

A hollow medullary cavity filled with yellow marrow runs the length of the diaphysis of a long bone. The walls of the diaphysis are compact bone. The epiphyses, which are wider sections at each end of a long bone, are filled with spongy bone and red marrow. The epiphyseal plate, a layer of hyaline cartilage, is replaced by osseous tissue as the organ grows in length. The medullary cavity has a delicate membranous lining called the endosteum. The outer surface of bone, except in regions covered with articular cartilage, is covered with a fibrous membrane called the periosteum. Flat bones consist of two layers of compact bone surrounding a layer of spongy bone. Bone markings depend on the function and location of bones. Articulations are places where two bones meet. Projections stick out from the surface of the bone and provide attachment points for tendons and ligaments. Holes are openings or depressions in the bones.

Bone matrix consists of collagen fibers and organic ground substance, primarily hydroxyapatite formed from calcium salts. Osteogenic cells develop into osteoblasts. Osteoblasts are cells that make new bone. They become osteocytes, the cells of mature bone, when they get trapped in the matrix. Osteoclasts engage in bone resorption. Compact bone is dense and composed of osteons, while spongy bone is less dense and made up of trabeculae. Blood vessels and nerves enter the bone through the nutrient foramina to nourish and innervate bones.

Review Questions

Critical Thinking Questions

1. If the articular cartilage at the end of one of your long bones were to degenerate, what symptoms do you think you would experience? Why?

2. In what ways is the structural makeup of compact and spongy bone well suited to their respective functions?


articular cartilage
thin layer of cartilage covering an epiphysis; reduces friction and acts as a shock absorber
where two bone surfaces meet
(singular = canaliculus) channels within the bone matrix that house one of an osteocyte’s many cytoplasmic extensions that it uses to communicate and receive nutrients
central canal
longitudinal channel in the center of each osteon; contains blood vessels, nerves, and lymphatic vessels; also known as the Haversian canal
compact bone
dense osseous tissue that can withstand compressive forces
tubular shaft that runs between the proximal and distal ends of a long bone
layer of spongy bone, that is sandwiched between two the layers of compact bone found in flat bones
delicate membranous lining of a bone’s medullary cavity
epiphyseal plate
(also, growth plate) sheet of hyaline cartilage in the metaphysis of an immature bone; replaced by bone tissue as the organ grows in length
wide section at each end of a long bone; filled with spongy bone and red marrow
opening or depression in a bone
(singular = lacuna) spaces in a bone that house an osteocyte
medullary cavity
hollow region of the diaphysis; filled with yellow marrow
nutrient foramen
small opening in the middle of the external surface of the diaphysis, through which an artery enters the bone to provide nourishment
cell responsible for forming new bone
cell responsible for resorbing bone
primary cell in mature bone; responsible for maintaining the matrix
osteogenic cell
undifferentiated cell with high mitotic activity; the only bone cells that divide; they differentiate and develop into osteoblasts
(also, Haversian system) basic structural unit of compact bone; made of concentric layers of calcified matrix
perforating canal
(also, Volkmann’s canal) channel that branches off from the central canal and houses vessels and nerves that extend to the periosteum and endosteum
fibrous membrane covering the outer surface of bone and continuous with ligaments
bone markings where part of the surface sticks out above the rest of the surface, where tendons and ligaments attach
spongy bone
(also, cancellous bone) trabeculated osseous tissue that supports shifts in weight distribution
(singular = trabecula) spikes or sections of the lattice-like matrix in spongy bone


Answers for Critical Thinking Questions

  1. If the articular cartilage at the end of one of your long bones were to deteriorate, which is actually what happens in osteoarthritis, you would experience joint pain at the end of that bone and limitation of motion at that joint because there would be no cartilage to reduce friction between adjacent bones and there would be no cartilage to act as a shock absorber.
  2. The densely packed concentric rings of matrix in compact bone are ideal for resisting compressive forces, which is the function of compact bone. The open spaces of the trabeculated network of spongy bone allow spongy bone to support shifts in weight distribution, which is the function of spongy bone.

Define and list examples of bone markings

The surface features of bones vary considerably, depending on the function and location in the body. Table 6.2 describes the bone markings, which are illustrated in (Figure 6.3.4). There are three general classes of bone markings: (1) articulations, (2) projections, and (3) holes. As the name implies, an articulation is where two bone surfaces come together (articulus = “joint”). These surfaces tend to conform to one another, such as one being rounded and the other cupped, to facilitate the function of the articulation. A projection is an area of a bone that projects above the surface of the bone. These are the attachment points for tendons and ligaments. In general, their size and shape is an indication of the forces exerted through the attachment to the bone. A hole is an opening or groove in the bone that allows blood vessels and nerves to enter the bone. As with the other markings, their size and shape reflect the size of the vessels and nerves that penetrate the bone at these points.

Bone Markings (Table 6.2)
ArticulationsWhere two bones meetKnee joint
HeadProminent rounded surfaceHead of femur
FacetFlat surfaceVertebrae
CondyleRounded surfaceOccipital condyles
ProjectionsRaised markingsSpinous process of the vertebrae
ProcessProminence featureTransverse process of vertebra
SpineSharp processIschial spine
TubercleSmall, rounded processTubercle of humerus
TuberosityRough surfaceDeltoid tuberosity
LineSlight, elongated ridgeTemporal lines of the parietal bones
CrestRidgeIliac crest
HolesHoles and depressionsForamen (holes through which blood vessels can pass through)
FossaElongated basinMandibular fossa
FoveaSmall pitFovea capitis on the head of the femur
SulcusGrooveSigmoid sulcus of the temporal bones
CanalPassage in boneAuditory canal
FissureSlit through boneAuricular fissure
ForamenHole through boneForamen magnum in the occipital bone
MeatusOpening into canalExternal auditory meatus
SinusAir-filled space in boneNasal sinus
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6.3 Bone Structure – Anatomy & Physiology (2024)


What are the major parts of a long bone module 6.3 A? ›

6.3a List the major parts of a long bone. The major parts of a long bone are the epiphysis, diaphysis, metaphysis, and medullary cavity.

What are the 6 structures of a long bone? ›

By the end of this section, you will be able to: Define and identify the following parts of a long bone: diaphysis, epiphysis, metaphysis, articular cartilage, periosteum, medullary cavity, endosteum.

What is normal bone structure? ›

The diaphysis is composed primarily of dense cortical bone, whereas the me- taphysis and epiphysis are composed of trabecular meshwork bone surrounded by a relatively thin shell of dense cortical bone. The adult human skeleton is composed of 80% cortical bone and 20% trabecular bone overall (3).

What is bone structure in anatomy? ›

Bones consist mostly of the protein collagen, which forms a soft framework. The mineral calcium phosphate hardens this framework, giving it strength. The bones contain 99% of the body's calcium. Bones have an internal structure similar to a honeycomb, which makes them rigid yet relatively light.

What is the 6 shaft or long main portion of a bone? ›

Diaphysis - Refers to the main part of the shaft of a long bone. Long bones, including the femur, humerus, and tibia, all have a shaft.

What are the 3 structures of long bones? ›

Long bones have a thick outside layer of compact bone and an inner medullary cavity containing bone marrow. The ends of a long bone contain spongy bone and an epiphyseal line. The epiphyseal line is a remnant of an area that contained hyaline cartilage that grew during childhood to lengthen the bone.

What are the 6 categories of bones based on their shape? ›

There are six types of bones in the human body: long, short, flat, irregular, sesamoid and sutural.

What are the main types of bone structure? ›

There are four different types of bone in the human body:
  • Long bone – has a long, thin shape. ...
  • Short bone – has a squat, cubed shape. ...
  • Flat bone – has a flattened, broad surface. ...
  • Irregular bone – has a shape that does not conform to the above three types.

What is each structure of the long bone? ›

Long bones have a thick outside layer of compact bone and an inner medullary cavity containing bone marrow. The ends of a long bone contain spongy bone and an epiphyseal line. The epiphyseal line is a remnant of an area that contained hyaline cartilage that grew during childhood to lengthen the bone.

What is a healthy bone level? ›

A T score of -1 to +1 is considered normal bone density. A T score of -1 to -2.5 indicates osteopenia (low bone density). A T score of -2.5 or lower is bone density low enough to be categorized as osteoporosis.

What should your bone percentage be? ›

Bone content is the percentage of bone mineral as compared to total body weight. The average bone content for adults is 3-5%. This measurement is good to keep track over a long period of time as bone mass can decline slowly with age.

What is normal range for bone test? ›

A T-score equal to or above -1.0 is considered normal bone density. A T-score between -1.0 and -2.5 is considered low bone density, sometimes referred to as osteopenia. A T-score -2.5 or below is considered osteoporosis.

What are the 6 functions of bone? ›

The human skeleton serves six major functions: support, movement, protection, production of blood cells, storage of ions, and endocrine regulation.

What are the 4 parts of the bone structure? ›

The Four Layers of Bone
  • Periosteum.
  • Cortical, or Hard Bone.
  • Cancellous, or Spongy Bone.
  • Bone Marrow.

What are the 7 types of bones? ›

The bones of the human skeleton are classified by their shape: long bones, short bones, flat bones, sutural bones, sesamoid bones, and irregular bones (Figure 1). Figure 1. Shown are different types of bones: flat, irregular, long, short, and sesamoid.

What is 6 What is the name of the largest bone in your body and where is located? ›

How big is the femur? Your femur is the largest bone in your body. Most adult femurs are around 18 inches long. The femur is also the strongest bone in your body.

How are bones classified by shape? ›

Bones can be classified according to their shapes. Long bones, such as the femur, are longer than they are wide. Short bones, such as the carpals, are approximately equal in length, width, and thickness. Flat bones are thin, but are often curved, such as the ribs.

What is the shaft of a bone called? ›

The diaphysis is the tubular shaft that runs between the proximal and distal ends of the bone. The hollow region in the diaphysis is called the medullary cavity, which is filled with yellow marrow.

What are bone cells called? ›

Bone is composed of four different cell types; osteoblasts, osteocytes, osteoclasts and bone lining cells. Osteoblasts, bone lining cells and osteoclasts are present on bone surfaces and are derived from local mesenchymal cells called progenitor cells.

What are the 3 major types of bones? ›

The four principal types of bones are long, short, flat and irregular. Bones that are longer than they are wide are called long bones.

What is the end of the bone called? ›

The wider section at each end of the bone is called the epiphysis (plural = epiphyses), which is filled internally with spongy bone, another type of osseous tissue.

What are bones Grade 6? ›

Bones and cartilage form the skeleton of the human body. It gives the frame and shape to the body and helps in movement. It protects the inner organs. The skeleton comprises the skull, the back bone, ribs and the breast bone, shoulder and hipbones, and the bones of hands and legs.

What are the 7 functions of bones? ›

The skeletal system is the body system composed of bones and cartilage and performs the following critical functions for the human body:
  • supports the body.
  • facilitates movement.
  • protects internal organs.
  • produces blood cells.
  • stores and releases minerals and fat.

What are the 5 major bone types? ›

How are they categorized? There are five types of bones in the skeleton: flat, long, short, irregular, and sesamoid.

What is the weakest bone in the body? ›

The clavicle, or collar bone, is the skin's softest and weakest bone.

What are 5 functions of bones? ›

It gives the body its shape, allows movement, makes blood cells, provides protection for organs and stores minerals. The skeletal system is also called the musculoskeletal system.

What are the 5 stages of bone growth? ›

There are five phases in the bone remodeling process: ACTIVATION, RESORPTION, REVERSAL, FORMATION, and QUIESCENCE. The total process takes about 4 to 8 months, and occurs continually throughout our lives.

What are 4 types of long bones? ›

The femur, or the thigh bone. The tibia, or the shin bone. The fibula, or the calf bone. The metatarsals, or some of the bones of the foot.

What is spongy bone also called? ›

Cancellous tissue, also known as cancellous bone, spongy bone or trabecular bone, is characterized by its spongy, porous, honeycomb-like structure and is typically found at the ends of long bones.

What is the scientific name for the backbone? ›

Also called spinal column, spine, and vertebral column.

Is 6.3 bone mass good? ›

Normal bone mass should be 3-5 percent, while body water percentage should on average be between 45 and 65 percent and muscle mass, about 75- 89 percent for men under 40 and 63-75.5 percent for women under 40.

Is 3.3 bone density good? ›

A T-score within 1 SD (+1 or -1) of the young adult mean indicates normal bone density. A T-score of 1 to 2.5 SD below the young adult mean (-1 to -2.5 SD) indicates low bone mass. A T-score of 2.5 SD or more below the young adult mean (more than -2.5 SD) indicates the presence of osteoporosis.

Which fruit is best for bones? ›

So, on that note, which is the best fruit for bones? Oranges, bananas, plantains, prunes, grapefruits, strawberries, papaya, pineapples, and guavas are examples of fruits high in vitamin C. In addition, fruits rich in vitamin K, like figs, blueberries, raspberries, plums, and grapes are healthy for bones.

Does bone size affect weight? ›

Big bones don't mean (much) extra weight

“Larger bones might account for a few pounds of weight but not 30 or 40,” Banaszynski said. “It's not going to be the difference between a healthy body mass index (BMI) and being overweight.”

What is a good body score? ›

Health score

It is calculated out of 100; the higher the score the better. A normal health score should be between 70-80, anything lower than a 60 is considered a health risk.

What is a good bone mass score? ›

If your T-score is: 1 or higher, your bone is healthy. –1 to –2.5, you have osteopenia, a less severe form of low bone mineral density than osteoporosis. –2.5 or lower, you might have osteoporosis.

What is a good result from a bone scan? ›

DXA Scan Results

T-score of -1.0 or above = normal bone density. T-score between -1.0 and -2.5 = low bone density, or osteopenia. T-score of -2.5 or lower = osteoporosis.

What do bone blood test results tell you? ›

A bone profile blood test analyses the proteins, minerals and enzymes present in your bones. These nutrients support healthy bone structure and development. A bone profile of blood tests helps to determine how well your body's metabolic processes are affecting your skeleton.

What is Stage 4 osteoporosis? ›

Stage 4, or severe, osteoporosis is associated with significant pain, impaired mobility, and stooped posture. A person has stage 4 osteoporosis if their bone mineral density score is more than 2.5 standard deviations below the healthy average for a young adult and they have had at least one fracture.

What bone protects the brain? ›

The cranium, or skull, is composed of 22 bones anis d divided into two regions: the neurocranium (which protects the brain) and the viscerocranium (which forms the face).

What are some diseases of the skeletal system? ›

Common Bone Disorders
  • Osteoporosis. This common disease occurs when bones become weak due to changes in bone mineral density and mass, causing a higher risk for fractures. ...
  • Fracture. ...
  • Scoliosis. ...
  • Paget's disease. ...
  • Osteoarthritis. ...
  • Rheumatoid arthritis. ...
  • Gout. ...
  • Bursitis.
Oct 12, 2020

Is bone a tissue or organ? ›

Bone is living tissue that makes up the body's skeleton. There are 3 types of bone tissue: Compact tissue.

What is the hardest bone in the body to break? ›

Answer: The human body consists of approximately 206 bones of which the femur is the heaviest and sturdiest bone.

Which is the strongest bone in our human body? ›

The femur is one of the most well-described bones of the human skeleton in fields ranging from clinical anatomy to forensic medicine. Because it is the longest and strongest bone in the human body, and thus, one of the most well-preserved in skeletal remains, it makes the greatest contribution to archaeology.

Why is cartilage slow to heal? ›

Cartilage, like bone, is surrounded by a perichondrium-like fibrous membrane. This layer is not efficient at regenerating cartilage. Hence, its recovery is slow after injury. The lack of active blood flow is the major reason any injury to cartilage takes a long time to heal.

What has 12 bones? ›

The spine above the sacrum consists of: Seven bones in the neck—the cervical spine. 12 bones in the chest—the thoracic spine.

What are the 206 bones called? ›

The adult human skeleton usually consists of 206 named bones. These bones can be grouped in two divisions: axial skeleton and appendicular skeleton. The 80 bones of the axial skeleton form the vertical axis of the body.

Is the skull a bone? ›

The bones that form the head. The skull is made up of cranial bones (bones that surround and protect the brain) and facial bones (bones that form the eye sockets, nose, cheeks, jaw, and other parts of the face). An opening at the base of the skull is where the spinal cord connects to the brain.

What are the major parts of a long bone quizlet? ›

The major parts of a long bone include epiphysis, articular cartilage, diaphysis, periosteum, medullary cavity, endosteum, and marrow.

What is the main part of the shaft of a long bone? ›

The diaphysis is the main or midsection (shaft) of a long bone. It is made up of cortical bone and usually contains bone marrow and adipose tissue (fat).

What is the main part of a long bone called? ›

A long bone has two parts: the diaphysis and the epiphysis. The diaphysis is the tubular shaft that runs between the proximal and distal ends of the bone. The hollow region in the diaphysis is called the medullary cavity, which is filled with yellow marrow.

What are the major parts of a bone? ›

Each bone has three main layers:
  • Periosteum: The periosteum is a tough membrane that covers and protects the outside of the bone.
  • Compact bone: Below the periosteum, compact bone is white, hard, and smooth. ...
  • Spongy bone: The core, inner layer of the bone is softer than compact bone.
Nov 19, 2019

What are the 3 main sections of a long bone external? ›

Long bones are longer than they are wide. They can be divided into three regions - epiphysis, metaphysis and the diaphysis.

What is the function of each part of the long bone? ›

Compact bone: This part provides support and protection to the bone. Diaphysis: It is involved in housing the bone marrow inside the bone. Periosteum: It has many roles, including delivering nutrients and oxygen to the bones, which helps promote the growth and development of the long bone.

What is the end of a long bone called? ›

A typical long bone shows the gross anatomical characteristics of bone. The wider section at each end of the bone is called the epiphysis (plural = epiphyses), which is filled with spongy bone.

What connects bone to bone? ›

Ligaments. Strong ligaments (tough, elastic bands of connective tissue) surround the joint to give support and limit the joint's movement. Ligaments connect bones together.

What is the head of a bone called? ›

Parts of a bone

Long bones are composed of four distinct parts: a head (epiphysis), a neck (metaphysis), a body (diaphysis), and an articular surface.

What is the bone in the neck called? ›

These are the seven bones of the neck, called the cervical vertebra. The top bone, seen on the right of this picture, is called the atlas, and is where the head attaches to the neck. The second bone is called the axis, upon which the head and atlas rotate.

What is bone made out of? ›

Bone is made up of compact tissue (the hard, outer layer) and cancellous tissue (the spongy, inner layer that contains red marrow). Bone tissue is maintained by bone-forming cells called osteoblasts and cells that break down bone called osteoclasts.


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