Chapter 6: Bone Tissue and the Skeletal System

Define bone, cartilage, and the skeletal system; list and describe the functions of the skeletal system; classify bones according to their shapes; describe the function of each category of bones; identify the anatomical features of a bone; define and list examples of bone markings; describe the histology of bone tissue; compare and contrast compact and spongy bone; identify the structures that compose compact and spongy bone; describe how bones are nourished and innervated

Bone

also called osseous tissue, is a living, mineralized connective tissue that makes up most of the skeleton; its matrix contains collagen fibers, which help it resist pulling forces, and calcium phosphate crystals, which give it hardness

Cartilage

a firm, flexible connective tissue; its cells, called chondrocytes, maintain a water-rich matrix that helps cartilage withstand pressure

Skeletal System

the organ system made up of bones, cartilage, joints, and ligaments; it provides the body’s framework, protects internal organs, and works with muscles to produce movement

example of what?

bones protecting the brain

Orthopedist

also called an orthopedic surgeon, is a physician who diagnoses and treats injuries and disorders of the musculoskeletal system, including the bones, joints, muscles, tendons, and ligaments; use both surgical and nonsurgical treatments

Yellow Marrow

a type of bone marrow made mostly of adipocytes (fat cells); it’s found primarily in the medullary cavity of adult long bones, such as the femur, and its main function is to store fat as an energy reserve

Red Marrow

also called red bone marrow, is the soft tissue inside certain bones

Hematopoiesis

the process of forming red blood cells, white blood cells, and platelets; in adults, it occurs mainly in red bone marrow, where hematopoietic stem cells divide and give rise to all three

example of what?

head of femur showing red and yellow marrow

examples of what?

examples of classifications of bones

Long Bone

a bone that is longer than it is wide

it has a central shaft called the diaphysis and two ends called epiphyses

the shaft contains a medullary cavity that typically holds yellow marrow in adults

Function of the Long Bone

Leverage

Examples of Long Bones

femur, tibia, fibula, metatarsals, humerus, ulna, radius, metacarpals, phalanges

Short Bone

a roughly cube-shaped bone that is about as long as it is wide; it has a core of spongy bone surrounded by a thin layer of compact bone

Functions of the Short Bone

provide stability and support while allowing for some motion

Examples of the Short Bone

carpals and tarsals

Flat Bone

a thin, flattened, often slightly curved bone; it typically has two layers of compact bone with a layer of spongy bone between them

Functions of the Flat Bone

points of attachment for muscles; protectors of internal organs

Examples of the Flat Bone

sternum, ribs, scapulae, cranial bones

Irregular Bone

a bone with a complex shape that falls outside the long, short, flat, and sesamoid categories

Function of the Irregular Bone

protect internal organs

Examples of the Irregular Bone

vertebrae and facial bones

Sesamoid Bone

a bone embedded within a tendon, usually where the tendon crosses a joint; it helps protect the tendon from pressure and can improve the muscle’s leverage at the joint

Function of the Sesamoid Bone

protect tendons from compressive forces

Example of the Sesamoid Bone

Patellae

Diaphysis

the shaft, or long middle portion, of a long bone; it lies between the two ends, called epiphyses

Epiphysis

(plural epiphyses) is the expanded end of a long bone; each long bone has a proximal epiphysis closer to the trunk and a distal epiphysis farther from the trunk

Medullary Cavity

also called the marrow cavity, is the hollow space inside the diaphysis (shaft) of a long bone; it’s surrounded by compact bone and lined by a thin membrane called the endosteum

Compact Bone

also called cortical bone, is the dense, hard tissue that forms the outer layer of bones; it’s especially thick in the diaphysis (shaft) of long bones, where it surrounds the medullary cavity

example of what?

anatomy of a long bone

Epiphyseal Plate

also called the growth plate, is a layer of hyaline cartilage in the metaphysis, between the shaft and end of a growing long bone

cartilage cells multiply on the side closer to the epiphysis (end), while cartilage is replaced by bone on the side closer to the diaphysis (shaft)

this process allows the bone to grow in length

Endosteum

a thin membrane that lines the internal surfaces of bone, including the medullary cavity, the trabeculae of spongy bone, and the canals within compact bone

Periosteum

a tough connective tissue membrane that covers the outer surface of a bone, except where articular cartilage covers the bone at a joint

Articular Cartilage

the smooth layer of cartilage that covers the ends of bones where they meet in a synovial joint, such as the knee; it reduces friction as the bones move and distributes pressure across the joint

Diploë

the layer of spongy bone between the inner and outer layers of compact bone in the flat bones of the skull; it consists of a network of thin bony struts called trabeculae, with marrow in the spaces between them

example of what?

anatomy of a flat bone

Articulation

also called a joint, is the place where two or more bones meet; some articulations allow a wide range of motion, like the shoulder joint, while others allow little or no movement, like the sutures between skull bones

Projection

a raised or protruding feature on the surface of a bone; projections can serve as attachment sites for muscles, tendons, or ligaments, or they can help form a joint

Hole

an opening in a bone

Articulator Bone Markings

features on a bone’s surface that meet another bone to form a joint; at synovial joints, these surfaces are usually covered by articular cartilage to reduce friction during movement

Example of Articular Bone Markings

knee joint

Head Bone Markings

a rounded, expanded articular surface at the end of a bone, often supported by a narrower region called the neck; it meets another bone to form a joint

Example of Head Bone Markings

head of femur

Facet Bone Markings

a smooth, nearly flat articular surface on a bone; it meets a matching surface on another bone to form a joint

Example of Facet Bone Markings

vertebrae

Condyle Bone Markings

a rounded, smooth projection, usually at the end of a bone, that forms part of a joint

Example of Condyle Bone Markings

occipital condyles

Projection Bone Markings

a raised feature that extends outward from the surface of a bone; some projections provide attachment sites for muscles, tendons, or ligaments, while others help form joints

Example of Projection Bone Markings

spinous process of the vertebrae

Protuberance Bone Markings

a bony prominence that bulges outward from the surface of a bone; it can serve as an attachment site for muscles or ligaments

Example of Protuberance Bone Markings

chin

Process Bone Markings

a projection that extends from a bone; it can serve as an attachment site for muscles or ligaments, or it can help form a joint

Example of Process Bone Markings

transverse process of vertebra

Spine Bone Markings

a sharp, slender, pointed projection from the surface of a bone; it can serve as an attachment site for muscles or ligaments

Example of Spine Bone Markings

ischial spine

Tubercle Bone Markings

a small, rounded projection on the surface of a bone; it often serves as an attachment site for a tendon or ligament

Example of Tubercle Bone Markings

tubercle of humerus

Tuberosity Bone Markings

a large, rounded, often rough projection on the surface of a bone; it typically serves as an attachment site for a tendon or ligament

Example of Tuberosity Bone Markings

deltoid tuberosity

Line Bone Markings

a low, narrow ridge on the surface of a bone; it often serves as an attachment site for muscles or other connective tissues