Skeletal System
•Made up of
bones
•In an adult
there are 206
bones
Functions of the Bone
1.Framework: support body’s muscles,
fat, and skin
Protection
a. surrounds vital organs to protect them
• examples: skull surrounding brain; ribs to
protect heart
• 3. Levers: attach to muscles to help provide
movement
• 4. Production of blood cells: red and white
blood cells and platelets
• 2.
Formation of bones
• Initially collagen
fibers secreted by
fibroblasts then
cartilage deposits
between fibers
• Skeleton fully formed
by 2nd month of fetal
development – all
cartilage
Formation continued…
• 8th week of fetal
development –
ossification
begins - which
is mineral
matter being
deposited and
cartilage is
replaced
Formation continued…
• During childhood and adolescence, ossification exceeds
bone loss
• During adulthood and middle age, ossification equals
bone loss
• After age 35, bone loss exceeds ossification
Bone Growth
• Grows in
length at the
epiphyseal line
• Grows in
width by
addition of
bone to the
surface
• Controlled
by anterior
pituitary
gland
(growth
hormone)
Four major types of bones
•long
•short
•flat
•irregular
Two sections of skeleton
• Axial –
forms main
trunk of
body;
composed
of the
skull, spinal
column,
ribs, and
sternum
• Appendicular forms
extremities
(arms and
legs);
composed of
shoulder
girdle, arm
bones, pelvic
girdle, and leg
bones
Axial skeleton
•Skull
• Composed of cranial and
facial bones
• Cranium
• Surrounds and protects
the brain
• Made of eight bones
•
•
•
•
•
•
Frontal
Two parietal
Two temporal
Occipital
Ethmoid
Sphenoid
• At birth the
cranium is not
solid bone
• Spaces called
fontanels or “soft
spots” allow for
enlargement of
skull as brain
growth occurs
• Fontanels are
made of
membrane and
cartilage
• Turn into solid
bone by about 18
months of age
Facial Bones
• Fourteen facial bones
1). Main bones
a). Mandible: lower jaw
b). Maxilla: two bones
forming upper jaw
c). Zygomatic: two cheek
bones
d). Nasal: five bones in
upper part of nose
e). Lacrimal: two bones at
inner aspect of eyes
f). Palatine: two bones of
hard palate or roof of
mouth
Sutures
• areas where
cranial bones
have joined
together
Sinuses
• a. Air spaces in the
bones of the skull
• b. Provide strength
with less weight
• c. Act as resonating
chambers for the
voice
• d. Lined with
mucous membranes
Foramina
• a. Openings
in bones
• b. Allow
nerves and
blood
vessels to
enter or
leave bone
Vertebrae
• Spinal column
made of 26
bones called
vertebrae
• Protect the spinal
cord
• Provide support
for head and
trunk
Main sections:
• Cervical: 7 neck vertebrae
• Thoracic: 12 vertebrae in
back of chest, attach to ribs
• Lumbar: 5 vertebrae by
waist
• Sacrum: 5 fused bones,
triangular in shape, forms
dorsal part of pelvis
• Coccyx: 3-4 fused bones,
called tailbone, slightly
moveable
Intervertebral Disks
• 1) Pads of
cartilage tissue
that separate
vertebrae
• 2) Act as shock
absorbers
• 3) Permit bending
and twisting
movements of
vertebral column
Ribs
• 1) 12 pairs of long slender bones
• 2) Attach to thoracic vertebrae on dorsal
surface of body
• a) True ribs: First 7 pairs of ribs; Attach directly
to sternum on front of body
• b) False ribs: Next 5 pairs of ribs; first 3 pairs
attach to cartilage of rib above
• c) Floating ribs: last two pairs of false ribs;
no attachment on front of body
Ribs continued…
Sternum
• Breastbone
1) Consists of three parts
a) Manubrium: upper region
b) Gladiolus: body or center
area
c) Xiphoid process: small
piece of cartilage at bottom
2. Two clavicles attach to the
manubrium by ligaments
3.Ribs attach to sternum with
costal cartilages to form a cage
that protects the heart and lungs
Appendicular Skeleton
Shoulder Girdle
(aka Pectoral Girdle)
• Two clavicles
• Two scapula's
(scapulae)
Upper Extremities
• Humorous: upper
arm
• Radius: thumb side of
forearm
• Ulna: Little finger side
of forearm
• Carpals (8): wrist
bones
• Metacarpals (5):
hand bones
• Phalanges (14): finger
bones
Pelvic Girdle
• Two os coxae:
contains the
acetabulum (hip
socket)
• Join with sacrum on
dorsal part of body
• Join together at a joint
called the pubic
symphysis on ventral
part of body
• Each os
coxae made
of three
bones that
are fused or
joined
• Ilium
• Ischium
• Pubis
Obturator foramen
• 1)
Opening
between the
ischium and pubis
• 2) Allows for
passage of nerves
and blood vessels
to and from the
legs
Lower Extremities
• Femur: thigh bone
• Patella: kneecap
• Tibia: medial bone in lower
leg, shin bone
• Fibula: Lateral bone of lower
leg, small than tibia
• Tarsals (7): ankle bones
(calcaneous is heel bone)
• Metatarsals (5): bones forming
instep of foot
• Phalanges (14): toe bones
Joints (a.k.a. Articulations)
• Synarthrotic
• Immovable
• Cranium
• Amphiarthrotic
• 1)Limited movement
• 2)pubic symphysis, vertebral joints, sacroiliac joint
• Diarthrotic
• Freely movable
• Gliding: wrist
• Pivot: between radius and ulna
• Ball and socket: hip, shoulder
• Hinge: elbow
Bone Composition, Shape &
Bone Marrow
Types of Bone Based
on Composition
1. Compact Bone
• Very dense
• Stress bearing
• Femur, tibia,
humorous
2. Cancellous Bone
• Light, spongy.
• Low stress areas where
weight of bone would be
a problem.
• Found at ends of long
bones, ribs, sternum,
hips, vertebrae, cranium.
Classification of Bones
According to Shape
Long Bones (extremities):
levers
1. Parts of long bones:
• Epiphysis: at ends, cancellous bone
• Diaphysis: shaft, compact bone
• Medullary Canal:
• Cavity in diaphysis
• Filled with yellow marrow
4. Endosteum:
• Membrane that lines
medullary canal
• Keeps yellow marrow
intact
• Produces some bone
growth
5. Periosteum:
• Tough membrane
covering outside of
bones
• Contains blood and
lymph vessels
• Contains osteoblasts:
special cells that form
new bone tissue
• Necessary for bone
growth, repair, and
nutrition
6. Articular
cartilage:
• Thin layer
covers the
epiphysis
• Acts as a shock
absorber when
two bones meet
to form a joint
7. Long bones include:
Femur
Tibia
Fibula
Humorous
Ulna
Radius
Clavicle
Short Bones
• Cubed shaped
• Allow flexible
movement
• Cancellous bone
covered by compact
bone
Short Bones include:
Flat Bones
• Flat plates
• Protect vital organs
• Provide broad surface area for
muscle attachment
Flat bones include:
Facial Bones
Scapula
Cranial Bones
Sternum
Irregular Bones
• Peculiarly shaped to provide support & protection
• Allows flexibility
Vertebra
Ribs
Hip bones
Ear bones
Hyoid bone
Sesamoid Bone
• Extra bones found in certain tendons.
Patella
Bone Growth
• Grow in length at epiphyseal line
• Grow in width by addition of bone to surface
• Controlled by anterior pituitary (growth
hormone)
Growth Hormone
Dysfunction
• Dwarfism: hypofunction
• Giantism: hyperfunction
• Acromegaly: hyperfunction after puberty;
enlarges bones of hands, feet, and face.
Bone Marrow
• Yellow Marrow
• Inside
medullary
canal
• Mainly fat cells
Bone Marrow continued…
• Red Marrow
1. Found in certain bones such as:
1. Vertebrae
2. Ribs
3. Sternum
4. Cranium
5. Proximal ends of humorous & femur
2. Produces RBC, platelets & some WBC
3. Important in the manufacture of blood &
is involved with the body’s immune response
4. Used in diagnosing blood diseases
5. Given as transplants to people with
defective immune systems
Diseases & Disorders of the
Skeletal System
Arthritis
• Inflammation of the bones at the
joints; usually with pain and
changes in bone structure.
Two Main Types of Arthritis:
•
Osteoarthritis
•
Rheumatoid Arthritis
Osteoarthritis
• Chronic disease that
occurs with aging
• Symptoms: joint pain,
stiffness, aching,
limited ROM
• Rx: Rest, heat/cold
applications, aspirin,
anti-inflammatory
medications, steroid
injections, special
exercises
Rheumatoid Arthritis
•
•
•
•
Chronic inflammatory disease of connective tissues and joints
Three times more common in women
Often begins between ages 35-45
Progressive attacks cause scar tissue formation and atrophy of
bone and muscle tissue resulting in permanent deformity and
immobility
• Rx: Rest and prescribed exercise
• Anti-inflammatory medications: aspirin and steroids
• Surgery or arthroplasty to replace damaged joints such as hips
or knees
Bursitis
• Inflammation of bursae (small fluid-filled
sacs surrounding joints)
• Frequently affects shoulders, elbows, hips,
or knees
• Symptoms: severe pain, limited
movement, accumulation of fluid in joint
• Rx:
• Pain medications and rest
• Injections of steroids and anesthetics
into joint
• Aspiration (withdrawal of fluid with a
needle) of joint
• Physical Therapy to preserve joint
motion
Fractures
•Involve a crack or break in a
bone
•Several Types of Fractures
Fractures--Greenstick
Bone is
bent and
splits
causing a
crack or
incomplete
break;
common in
children
Fractures-Simple
Complete break with no damage
to skin
Fractures--Compound
Break in bone that ruptures
through skin; increased chance of
infection
Fractures--Impacted
Broken bone ends jam into
each other
Fractures-Comminuted
Bone fragments or splinters into more
than two pieces
Fractures-Spiral
Severe
twisting of
a bone
causes one
or more
breaks;
common in
skiing and
skating
accidents
Fractures-Depressed
Broken piece of skull bone moves
inward; common with severe head
injuries
Fracture-Colles
Breaking and
dislocation of the
distal radius that
causes a
characteristic
bulge at the
wrist; caused by
falling on an
outstretched
hand
Reduction:
•Process by which bone is
put back into proper
alignment
• Closed reduction: position bone in
alignment, usually with traction, and
apply cast or splint to maintain position
• Open reduction: surgical repair of
bone, and sometimes the insertion of
pins, plates, and other devices
Dislocation
• Bone is forcibly displaced from a joint
• Frequently occurs in shoulders, fingers,
knees, and hips
• Reduced and immobilized with splint, cast,
or traction
Sprain
• Twisting action tears
ligaments at a joint
• Common sites are wrists
and ankles
• Symptoms: pain, swelling,
discoloration, limited
movement
• Rx: Rest and elevation
• Immobilization with elastic
bandage or splint
• Cold applications
Osteomyelitis
• Inflammation of bone usually
caused by pathogenic
organism
• Pathogen causes formation of
abscess within bone and
accumulation of pus in
medullary canal
• Symptoms: pain at site,
swelling, chills, fever
• Rx: antibiotics for infection
Osteoporosis
• Metabolic disorder with increased porosity or
softening of bones
• Etiology
• Deficiency of hormones, especially estrogen in females
• Prolonged lack of calcium in diet
• Sedentary lifestyle
• Loss of calcium and phosphate causes bones to
become porous, brittle, and prone to fracture
• Bone density tests lead to early detection and
preventative treatment
• Rx:
•
•
•
•
Increased intake of calcium and vitamin D
Exercise
Medications to increase bone mass
Estrogen replacement
Ruptured
Disk
• Also called a herniated or slipped disk
• Intervertebral disk ruptures or protrudes out of
place and causes pressure on the spinal nerve
• Most common site is lumbar-sacral area; can occur
anywhere on spinal column
• Symptoms: severe pain, muscle spasm, impaired
movement and/or numbness
• Rx:
•
•
•
•
•
•
Pain, anti-inflammatory, and muscle relaxant medications
Rest and traction
Physical therapy and massage therapy
Chiropractic treatment
Heat or cold applications
Laminectomy: surgical removal of the protruding disk for
severe cases
Spina Bifida
• Congenital defect in which the vertebrae fail
to unite in midline
• May require surgery
• Severity may cause paralysis
Abnormal curvatures of
spinal column
• Kyphosis: “hunchback” or rounded bowing of the
back at the thoracic area
• Scoliosis: side-to-side or lateral curvature of spine
• Lordosis: “swayback”: or abnormal inward curvature
of lumbar vertebrae
Causes or abnormal curvatures:
• poor posture
• congenital defects
• structural defects of vertebrae
• malnutrition
• degeneration of vertebrae
• Rx:
• Therapeutic exercises, firm
mattresses and braces
• Surgical repair for severe
deformities
Growth Hormone
Disorders
• Dwarfism:
hypofunction
• Gigantism:
hyperfunction
Acromegaly: hyperfunction
after puberty; enlarges bones
of hands, feet, face