ST110
Concorde Career College, Portland
SKELETAL SYSTEM
Objectives
 Define the term skeleton.
 Describe the functions of the skeletal system.
 List and identify the structures of the skeletal
system and describe the function of each.
 Identify the types of bone.
Objectives
 List the types of joints and describe the
function of each.
 List the classifications of bone and provide
examples of each.
 Describe the processes of bone formation
and bone healing.
Objectives
 Describe the mechanism by which the skeletal
system helps to maintain homeostasis.
 Describe common diseases, disorders, and
conditions of the skeletal system including signs
and symptoms, diagnosis, and available
treatment options.
 Demonstrate knowledge of medical terminology
related to the skeletal system verbally and in the
written form.
Skeleton
Introduction
 Includes all bones of the body (206) and includes
cartilage, tendons, and ligaments
 Cartilage – connective tissue that provides a smooth
surface for bone movement (articulation)
 Ligaments – connective tissue that attaches bone to
bone (ligaments also support abdominal organs)
 Tendons – connective tissue that attaches muscle to
bone
 Serves as a framework for the body
 Composed of living tissue
Functions
 Supports and stabilizes surrounding tissues such
as muscles, blood vessels, nerves, fat, and skin
 Protects vital body organs such as the brain,
spine, heart, and lungs and protects other soft
tissues of the body
 Assists in body movement by providing
attachments for muscles that pull on bones
 Matures blood cells
 Stores mineral salts (e.g., calcium)
Types of Bone Cells
 Osteoprogenitor - Stem cell that is
destined to become bone
 Osteoblast - Bone building cell
 Osteocyte - Mature bone cell
 Osteoclast - Resorption (breakdown)
Bone Cells
 Osteoprogenitor (osteogenic) Cells:
 Stem cells of skeletal tissue
 Composes the Inner layer of periosteum and the
single layer of endosteum
 Functions: formation of fetal bone and repair of
fractures
 Differentiate into Osteoblasts (good blood supply)
and Chondroblasts (limited blood supply)
Bone Cells
 Osteoblasts:
 form bone matrix
 Develop into osteocytes
 Osteocytes:
 responsible for maintaining bone matrix (develop
into osteoblasts)
 Osteoclasts:
 Breakdown and resorption of bone
 Activated by parathyroid hormone
 Differentiated from blood monocytes
Bone Cells
Growth and Development
 Osseous tissue
 Longitudinal growth occurs until the age of
15-16
 Bone maturation occurs around the age of 21
Embryonic Development of Bone
 Skelton is initially composed of cartilage and
gradually replaced with bone via two
methods
 Intramembranous Ossification: Develops flat
bones of the cranium, facial bones, Mandible and
clavivle
 Endochondrial Ossification: long bones, etc. (the
rest of the bones) Cartilage > Bone
Embryologic Development
Epiphyseal Plate
 Located at the junction between the
diaphysis and each epiphysis
 Area of growth (allows bone to lengthen)
 Around age 16-25 Epiphyseal plate ossifies
marking full maturity (end of growth)
Epiphyseal Plate
Epiphyseal Plate
Bone Remodeling
 Bones undergo a lifetime of remodeling and adapting to
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stress
Remodeling maintains bone structure and strength as
well as ensures constant supply of calcium to the body
Osteoclasts absorb bone that is then replaced by new
compact bone
When low blood calcium levels are detected parathyroid
hormone releases and stimulates the osteoclasts. When
high blood calcium occurs, calcium is stored in bone.
When normal blood calcium levels are reached the
thyroid releases calcitonin. Calcitonin inhibits
osteoclasts and stimulates osteoblasts (negative
feedback loop)
Factors that Affect Bone
Maintinance
 Hormonal influence
 Exercise: weight-bearing exercise is important in maintaining
bone strength
 Osteoporosis: results when bone matrix is lost faster then
replaced
 Nutrition: key factor in maintenance of normal bones
 Scurvy: results form a deficiency in vitamin C, shaft of long
bone becomes thin and fragile predisposing the person to
fractures
 Rickets: results form vitamin D deficiency, causes poorly
calcified, semiriged bones that bend under bodies weight
(bowed legs, knock-knees)
Scurvy
Rickets
Two Types of Bone
1. Cortical - Hard compact bone found in the
shaft of long bones and makes up the outer
layer of all other bones.
2. Cancellous (trabecular) - Soft spongy bone
found at the ends of long bones and at the
center of all other bones.
Compact Bone 75%
Spongy Bone 25%
Bone Types
Cortical Bone
 Dense and strong
 Osteon (Haversian System)
 Rings of mineral salts that allow bone cell
metabolism
 Central Canals
 Small canals that contain blood vessels
 Lamella-surrounds central canals
 Lacunae-tiny cavities in between lamella that
contain osteocytes
Cortical Bone
 Canaliculi-connect the lacunae and central
canals
 Haversian (perforating) canals-run
horizontally and contain blood vessels
Haversian System
Cancellous Bone
 Spongy bone
 Located at the ends of long bones and forms
the center of all other bones
 Trabeculae
 Meshwork of interconnecting bone secretions
 Gives strength to bone
 Filled with lamellae and osteocytes
Skeletal System
Bone Membranes
 Periosteum - Covers the outside of the bone
with the exception of the articulating surface
and contains osteoblasts for bone growth and
repair.
 Endosteum - Lines the marrow cavity and
also contains growth and repair cells.
Periosteum
 Layer of fibrous tissue that surrounds bone
 Functions:
 Layer of defense to protect from infection
 Forms new bone cells
 Full of nerves and blood vessels to aid in nourishment
of bone
 Attachment for tendons and ligaments
 **Due to these various functions the orthopedic
surgeon will approximate the periosteal layer when
incised
Periosteum
Medullary Canal
 Canal that runs down the middle of bone
 Contains semisolid tissue Red Bone Marrow
 Located in the spaces of spongy bone found in the
ends of long bones, sternum, vertebrae, and ribs
 In adults RBM is replaced with yellow bone marrow
 Functions: production of erythrocytes, leukocytes, and
platelets
 Endosteum: fibrous layer of tissue that lines
medullary cavity
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Bone Marrow
Red Bone Marrow
 Fills in spaces in cancellous bone
 Richly supplied with blood
 Hematopoiesis
 Blood cells in all stages of development
 Gradually decreases with age
Bone Marrow
Yellow Bone Marrow
 Contains fat cells
 Found in the medullary cavity (canal)
Bone Identification
 Shapes
 Long
 Short
 Flat
 Irregular
 Sesamoid
 Markings
 Projections
 Depressions
Bone Shapes
Long Bones
 Length exceeds width
 Diaphysis-shaft of mainly compact bone
 Thickness
 Curvature
 Medullary cavity
 Femur, radius, humerus
Structure of a Long Bone
Long Bones
 Metaphysis-flared portion on each end
consisting of spongy bone
 Epiphysis-on the end out from the
metaphysis consisting of spongy bone
 Epiphyseal line (plate - growth)
Short Bones
 No long axis
 Irregular shaped
 Thin layer of compact tissue over cancellous
 Carpal bones
Flat Bones
 Very thin bones that attach to muscle and/or
protect vital areas
 Sternum, bones of the skull
Flat Bones
Irregular Bones
 Very strange shape
 Layers of Compact bone over spongy bone
 Ossicles, vertebrae
Irregular Bones
Sesamoid Bone
 Small, round
 Enclosed in a tendon
 Adjacent to joints
 Kneecap, patella
Sesamoid Bone
Bone Markings-Processes
(projections)
 Obvious bony prominence
 Types
 Spine-sharp, slender projection
 Condyle-rounded or knuckle-like prominence
 Tubercle-small round process
 Trochlea-process shaped like a pulley
 Trochanter-very large projection
Bone Markings-Processes
 Crest - narrow ridge of bone
 Line - a little less prominent ridge of bone
 Head - an enlargement at the end of the
terminal
 Neck - part of a bone that connects the head
or terminal enlargement to the rest of the
bone
Bone Marking-Fossae
(depression)
 Any depression or cavity in or on a bone
 Types
 Suture-narrow junction many times found between
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two bones
Foramen-an opening in which blood vessels, nerves
and ligaments pass
Meatus (canal)-long, tube-like passage
Sinus (antum)-cavity within a bone
Sulcus-furrow or groove
Divisions of the Skeleton
 Axial - Head and trunk (80 Bones)
 Appendicular - Extremities and their
attachments (shoulder and pelvic girdles)
(126 Bones)
Divisions of the Skeleton
Axial
Appendicular
Axial Skeleton
Axial Skeleton
Skull, Facial
Axial Skeleton
Axial Skeleton
Hyoid Bone
Hyoid Bone
Axial Skeleton
Axial Skeleton
Vertebral Column
Axial Skeleton
Atlas
Axis
Vertebral Types
Axial Skeleton
Vertebra
Axial Skeleton
Sternum
Appendicular Skeleton
Appendicular Skeleton
Appendicular Skeleton
Appendicular Skeleton
Appendicular Skeleton
Appendicular Skeleton
Appendicular Skeleton
Knee Joint
Knee Joint
Arthroscopy- visual examination
of the internal structure of a
joint.
LIGAMENTS
Ligaments- A white band of fibrous connective
tissue. Connects Bone to Bone
TENDONS
Tendons- Bands or cords of fibrous connective
tissue that connect muscle to bone
Appendicular Skeleton
Appendicular Skeleton
Articulation
Articulation - Place of union (joint) between
two or more bones, regardless of movement
Types of Joints
Synarthroses
 Joints between bones that do not allow
movement
 Suture-bones united by a thin layer of fibrous
tissue
 Syndesmosis-joints are connected by ligaments
between the bones
 Gomphosis-a conical process fits into a socket and
is held by ligaments
Amphiarthroses
 Joints that allow only slight movement
 Symphysis-joints where the bones are connected
by a disk of fibrocartilage
 Synchondrosis-two bony surfaces are connected
by hyaline cartilage
 Replaced by permanent bone later in life
Synovial Joints
(Diarthroses)
 Freely moving joints
 Contain a cavity enclosed by a capsule reinforced
by ligaments
 Synovial fluid
 Provides a smooth gliding surface
 Nourishes the articular cartilage
Synovial Joints
(Diarthroses)
 Ball and socket joint
 Ball shaped head fits into a concave socket
 Multiaxial joint-Movement can occur in all planes and
directions
 Hinge joint
 Uniaxial joint-Movement is limited to flexing and
extending
 Pivot Joint
 Uniaxial joint
 Limited to rotation in a single plane
Synovial Joints
(Diarthroses)
 Condyloid joint
 Biaxial joint-motion is possible in two planes at right
angles to each other
 Oval-shaped condyle fits into a cavity
 Saddle Joint
 Biaxial
 One articular surface is concave in one direction and
convex in the other, the other articular surface is
reciprocally convex and concave
 Two bones fit together
Synovial Joints
(Diarthroses)
 Gliding joint
 Multiaxial
 Only allows gliding movement
Synovial Joint Movement
 Flexion-bending or decreasing the angle
between bones
 Extension-increasing the angle between
bones-opposite of flexion
 Hyperextension-increases the joint angle
beyond the anatomic position
Synovial Joint Movement
 Abduction-moving the bones or limbs away
from the midline
 Adduction-moving the bones or limbs toward
the midline
 Rotation-moving the bone around a central
axis-rotating your head
 Circumduction-moving a bone or limb so that
it describes a circle in the air
Synovial Joint Movement
 Supination-movement of forearm and hand so
that the radius and ulna are parallel
 Pronation-movement of the forearm and hand
so that the radius and ulna are not parallel
 Eversion-moving the sole of the foot outward at
the ankle
 Inversion-moving the sole of the foot inward at
the ankle
Synovial Joint Movement
 Protraction-moving part of the body forward
on a plane parallel to the ground
 Retraction-moving a part of the body
backward on a plane parallel to the ground
 Elevation-raising a part of the body
 Depression-lowering a part of the body
Synovial Joint Movement
 Opposition-when the tip of the thumb and
fingers are brought together
 Reposition-when the fingers return to their
normal position
 Dorsiflexion-raising the foot up at the ankle
 Plantar flexion-pushing the foot down at the
ankle
Bursae
 Closed sacs with a synovial membrane lining
 Found in spaces between tendons, ligaments
and bones
 Facilitate the gliding of muscle over muscle or
tendons over bony ligament surfaces
Joint Disorders
 Bursitis
 Inflammation of the synovial bursae
 Caused from excessive stress or tension
 Eventual degeneration
 Arthritis
 Inflammation of the whole joint
 Affects all tissues of a joint with over 100 varieties
Joint Disorders
 Rheumatoid Arthritis
 CT disorder resulting in severe inflammation of small
joints
 A layer forms from abnormal growth of the synovial
membrane and the surrounding CT that destroys
cartilage and starts to fuse the bones of the joint
Joint Disorders
 Osteoarthritis
 Affects weight bearing joints
 Degenerative joint disease
 Gout
 Accumulation of uric acid crystals in the base of
the large toe and other joints of the feet and legs
Types of Fractures
Classification of Fractures
 Compound (Open Fracture): fractured bone
pierces the skin
 Simple (Closed Fracture): fracture that does
not pierce the skin
 Complete: fracture line continuous through
bone
 Incomplete (Partial): may bend on one side
and break on the other (ex. Greenstick
fracture)
Classification of Fractures
 Linear: fracture runs parallel to the axis of the
bone
 Spiral: fracture line curves around the bone
 Transverse: fracture line is across the bone
 Pott’s Fracture: break of the lower fibula
Classification of Fractures
COLLES
A fracture of the distal end
of the radius in which the
distal fragment is displaced
posterioraly
Classification of Fractures
COMPRESSION
Aka-vertebral crush fracture.
Bone is pressed together or
compressed on itself
Types of Fractures
 Avulsion: Bone and other tissues are pulled
from normal attachments
 Bucket Handle: Dual vertical
fractures on the same side of
the pelvis
 Comminuted: Fracture with
more than two pieces of bone
fragment
 Butterfly: butterfly-shaped
pieces of fractured bone
 Compound (open):
broken end of bone
has penetrated skin
exposing bone
Types of Fractures
 Depressed: occurs
when bone is driven
inward
 Displaced: bone ends
are out of alignment
Types of Fractures
 Greenstick: bone splits longitudinally and is
not a complete break
Types of Fractures
 Impacted: broken
ends of bone are
forced into eachother
 Intra-articular: bones
inside a joint are
fractured
Types of Fractures
 Oblique: occurs at an
oblique angle across
bone
 Spiral: fracture that
curves around bone
Types of Fractures
 Simple: fracture is in normal anatomic
position and the skin is not borken
 Spontaneous: occurs without trauma
 Stellate: fracture occurs at central point in
which additional breaks in bone radiate form
the central point
Types of Fractures
 Transverse: horizontal fracture
through the bone
Normal Bone Healing
 Heals in approx. 8-12 weeks
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Bone ends must be aligned
Site of injury must be completely immobilized (case, external or internal
fixation)
 Inflammatory Stage:
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Begins when fracture occurs & lasts approx. 2 days
Hematoma forms
 Cellular proliferation stage:
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Begins approx. 3rd day
Macrophages: debridement
Fibrin mesh forms (seals the approximated edges)
Ingrowth of capillaries and fibroblasts begins
Normal Bone Healing
 Callus formation:
 Lasts 3-4 weeks
 Cartilage, immature bone, and fibrous tissue provide
stabilization to the fracture site
 Ossification Stage:
 Lasts 3-4 months
 Bone calcifies completing union of bone ends
 Remodeling:
 return of homeostasis
 Bone is mature and resumes all normal functions
Normal Bone Healing
Abnormal Curvatures of the
Spine
A. Kyphosis
B. Lordosis
C. Scoliosis
Diseases of the Skeletal
System
 Rickets
 Deficiencies in Vitamin D
 Fracture
 Breaking bone and harming surrounding tissue
 Scoliosis
 Curving of the spine
 Abnormal vertebral structure, muscle paralysis
Diseases of the Skeletal
System
 Osteoporosis
 Decrease in bone mass
 Increased susceptibility for fractures
 Decrease in estrogen
 Stimulate osteoblasts
Diseases of the Skeletal
System
 Paget’s Disease
 Irregular thickening and softening of bone
 Gigantism
 Abnormal endochondral ossification at the
epiphyseal plates on long bones-abnormally large
limbs
 Dwarfism
 Inadequate ossification
Diseases of the Skeletal
System
 Spina bifida
 Herniated Disk
 Rupture of fibrocartilage around intervertebral
disk
 Severe pain
Normal Disc
Herniated Disc
Ruptured Disc
Bone Scan
Radiograph
Fractured Femur
Total Joint Replacement