The Skeletal The Skeletal System:System:

Structure, Function, Structure, Function, and Diseasesand Diseases

of the bones and of the bones and jointsjoints

The Skeletal SystemThe Skeletal System Parts of the skeletal system

Bones (skeleton)

Joints

Cartilages

Ligaments (bone to bone)(tendon=bone to muscle)

Divided into two divisions

Axial skeleton

Appendicular skeleton – limbs and girdle

Functions of BonesFunctions of Bones

Support of the body

Protection of soft organs

Movement due to attached skeletal muscles

Storage of minerals and fats

Blood cell formation

Bones of the Human BodyBones of the Human Body

The skeleton has 206 bones

Two basic types of bone tissue

Compact bone

Homogeneous

Spongy bone

Small needle-like pieces of bone

Many open spaces

Microscopic Anatomy of BoneMicroscopic Anatomy of Bone

Bones are classified by their shape:

1.long 2.short 3.flat 4.irregular

Classification of Bones on the Classification of Bones on the Basis of ShapeBasis of Shape

Classification of BonesClassification of Bones

Long bones

Typically longer than wide

Have a shaft with heads at both ends

Contain mostly compact bone

• Examples: Femur, humerus

Gross Anatomy of a Long BoneGross Anatomy of a Long Bone

Diaphysis

Shaft

Composed of compact bone

Epiphysis

Ends of the bone

Composed mostly of spongy bone

Structures of a Long BoneStructures of a Long Bone Periosteum

Outside covering of the diaphysis

Fibrous connective tissue membrane

Sharpey’s fibers Secure periosteum to

underlying bone

Arteries Supply bone cells

with nutrients

Classification of BonesClassification of Bones

Short bones

Generally cube-shape

Contain mostly spongy bone

Examples: Carpals, tarsals

Classification of BonesClassification of Bones

Flat bones

Thin and flattened

Usually curved

Thin layers of compact bone around a layer of spongy bone

Examples: Skull, ribs, sternum

Classification of BonesClassification of Bones

Irregular bones

Irregular shape

Do not fit into other bone classification categories

Example: Vertebrae and hip

Surface features of bones

Sites of attachments for muscles, tendons, and ligaments

Passages for nerves and blood vessels

Categories of bone markings

Projections and processes – grow out from the bone surface

Depressions or cavities – indentations

Types of Bone CellsTypes of Bone Cells Osteocytes

Mature bone cells

Osteoblasts Bone-forming cells

Osteoclasts Bone-destroying cells

Break down bone matrix for remodeling and release of calcium

Bone remodeling is a process by both osteoblasts and osteoclasts

Changes in the Human SkeletonChanges in the Human Skeleton

In embryos, the skeleton is primarily hyaline cartilage

During development, much of this cartilage is replaced by bone

Cartilage remains in isolated areas

Bridge of the nose

Parts of ribs

Joints

Bone GrowthBone Growth

Epiphyseal plates allow for growth of long bone during childhood

New cartilage is continuously formed

Older cartilage becomes ossified

Cartilage is broken down

Bone replaces cartilage

Bone FracturesBone Fractures

A break in a bone

Types of bone fractures

Closed (simple) fracture – break that does not penetrate the skin

Open (compound) fracture – broken bone penetrates through the skin

Bone fractures are treated by reduction and immobilization

Realignment of the bone

Common Types of FracturesCommon Types of Fractures

Stages in the Healing of a Bone Stages in the Healing of a Bone FractureFracture

Axial skeleton supports and protects organs of head, neck and trunk Axial skeleton:

skull (cranium and facial bones) hyoid bone (anchors tongue and muscles

associated with swallowing) vertebral column (vertebrae and disks) bony thorax (ribs and sternum)

Appendicular skeleton includes bones of limbs and

bones that anchor them to the axial skeletonAppendicular skeleton:

pectoral girdle (clavicles and scapulae)upper limbs (arms)pelvic girdle (sacrum, coccyx)lower limbs (legs)

Articulation- where joints meet, connect, and are formed.

22 bones in skull6 in middle ears1 hyoid bone26 in vertebral column25 in thoracic cage

4 in pectoral girdle60 in upper limbs60 in lower limbs2 in pelvic girdle

206 bones in all

The Axial SkeletonThe Axial Skeleton

Forms the longitudinal part of the body

Divided into three parts

Skull

Vertebral column

Bony thorax

The Axial SkeletonThe Axial Skeleton

The skull

8 sutured bones in craniumFacial bones: 13 sutured bones, 1 mandible

Craniumencases brainattachments for musclessinuses

Bones of the SkullBones of the Skull

Allows forgrowth

Human Skull, Superior ViewHuman Skull, Superior View

Human Skull, Inferior ViewHuman Skull, Inferior View

Figure 5.9

Paranasal SinusesParanasal Sinuses

Hollow portions of bones surrounding the nasal cavity

The Hyoid BoneThe Hyoid Bone

The only bone that does not articulate with another bone

Serves as a moveable base for the tongue

The Vertebral ColumnThe Vertebral Column

Vertebrae separated by intervertebral discs

The spine has a normal curvature

Each vertebrae is given a name according to its location

Vertebral column

7 cervial vertebrae12 thoracic5 lumbar1 sacrum (5 fused 1 coccyx (4 fused)

Vertebrae vary in size and morphology

Structure of a Typical VertebraeStructure of a Typical Vertebrae

Thoracic cageribsthoracic vertebraesternumcostal cartilages

True ribs are directly attached to the sternum(first seven pairs)Three false ribs are joined to the 7th ribTwo pairs of floating ribs

Joints• Fibrous-Fibrous joints connect bones without

allowing any movement. The bones of your skull and pelvis are held together by fibrous joints.

• Cartilaginous-Cartilaginous joints are joints in which the bones are attached by cartilage. These joints allow for only a little movement, such as in the spine or ribs.

• Synovial-Synovial joints allow for much more movement than cartilaginous joints. Cavities between bones in synovial joints are filled with synovial fluid. This fluid helps lubricate and protect the bones. Bursa sacks contain the synovial fluid. within fixed limits

• A joint, or articulation, is the place where two bones come together.

• There are three types of joints classified by the amount of movement they allow:

Immovable slightly movable freely movable

Types of JointsHinge- A hinge joint allows extension and

retraction of an appendage. (Elbow, Knee)

Ball and Socket- A ball and socket joint allows for radial movement in almost any direction. They are found in the hips and shoulders. (Hip, Shoulder)

Gliding- In a gliding or plane joint bones slide past each other. Mid-carpal and mid-tarsal joints are gliding joints. (Hands, Feet)

Saddle- This type of joint occurs when the touching surfaces of two bones have both concave and convex regions with the shapes of the two bones complementing one other and allowing a wide range of movement. (Thumb)

Structures Associated with the Structures Associated with the Synovial JointSynovial Joint Bursae – flattened fibrous sacs

Lined with synovial membranes

Filled with synovial fluid

Not actually part of the joint

Tendon sheath

Elongated bursa that wraps around a tendon

The Synovial JointThe Synovial Joint

Types of Synovial Joints Based on Types of Synovial Joints Based on ShapeShape

Types of Synovial Joints Based on Types of Synovial Joints Based on ShapeShape

Diseases and Conditions

of the Skeletal System

Arthritis

Bursitis• Inflammation of the Bursa sac• can become inflamed from injury

or infection• localized pain or swelling

Tendonitis• inflammation of the tendon.• movement becomes painful. • most common cause of tendonitis

is overuse.

Carpal Tunnel Syndrome

• swelling or change in position of the tissue within the carpal tunnel squeezes and irritates the median nerve.

• causes tingling and numbness of the thumb, index, and the middle fingers

Osteoporosis• means "porous bones." • bones have lost minerals

(especially calcium) making them weak, brittle, and susceptible to fractures

• most common places where fractures occur are the back, hips, and wrists.

Scoliosis• abnormal curvature of the spine. • one or more abnormal • More girls than boys have severe

scoliosis.

Kyphosis• spine may develop a hump. • can occur as a result of

developmental problems or degenerative diseases

Lordosis• A curvature of the vertebrae in the

lower back area, giving a "swayback" appearance.

Rickets• softening and weakening of bones

in children• usually because of an extreme and

prolonged vitamin D deficiency.

Gout• results from an overload of uric acid in

the body. • leads to the formation of urate crystals

that deposit in the joints. • crystals in the joints causes recurring

attacks of joint inflammation (arthritis). • Chronic gout may cause joint

destruction, decreased kidney function, and kidney stones.

Acromegaly• occurs when the body produces

too much of the hormones that control growth.

• tissues grow larger than normal. • excessive growth can cause

serious disease and even premature death.

Spina Bifida• birth defect that involves the

incomplete development of the spinal cord or its coverings.

• spina bifida literally means "split" or "open" spine.

• The condition usually is detected before a baby is born and treated right away.

Talipes Equinovarus- “Clubfoot”

• deformity of the whole foot that is present at birth.

• the child is born with the foot pointing down and twisted inwards at the ankle.

Sarcoma• Osteosarcoma• most common type of bone

cancer. most commonly found in children and adolescents

Myeloma• cancer in which abnormal cells

collect in the bone marrow and form tumors

Leukemia• cancer of the blood cells• starts in the bone marrow where

blood cells are • the bone marrow starts to make a

lot of abnormal white blood cells, called leukemia cells.

• leukemia cells don't do the work of normal WBC’s and they don't stop growing when they should.

Bone Marrow Biopsy