The Skeletal System
Functions of Bones
Support
1.


Soft tissue
Attachment of tendons
Protection
3. Assistance in movement
4. Mineral homeostasis
2.

Release minerals when
needed


99% of the body’s calcium
is stored in bone.
85% of the body’s
phosphorous is stored in
bone.
Continued
Blood cell production
(hemopoiesis)
6. Triglyceride storage
5.
Red Marrow vs Yellow Marrow
 Red marrow
 Yellow marrow
 Made (hemopoiesis) in the
 Stored in medullary cavity
spongy bone
 Consists of adipocytes,
fibroblasts and
macrophages
 Later changes to yellow
marrow
 Consists of adipocytes
which store fat
 Can be an energy reserve
Types of Bones
1. Long Bones
 Much longer than they
are wide
 Curved for strength
2. Short Bones
 Roughly cube shaped
 Equal in length and width
Carpal Bones
Continued
3.
Flat Bones
 Thin
 Large surface area for
muscle attachment
Sternum
4.
Irregular Bones
 Weirdly shaped
All Bones
 Compact Bone
 Solid outer layer
 Spongy bone
 a network of flat, needle-like
projections called trabeculae.
Structure of Long Bone
Structure of Long Bone
 Articular cartilage
 Type of hyaline cartilage
 Cushions bones and
reduces friction
 Periosteum
 Supplied with nerve fibers
and blood vessels
 Assists in growth and
repair
 Endosteum
 Contains a single layer of
bone forming cells
Structure of “other” types of Bones
 Compact (covered by
periosteum)
 Spongy bone (lined with
endosteum)
 Called the diploe
 Bone marrow made between
trabeculae
Osseous Tissue
Extracellular matrix contains:
 Water
 Collagen fibers (flexibility)
 Crystalized mineral salts
(mostly calcium
phosphorous)
 Is bone completely solid?
This bone:
a. Has been demineralized
b. Has had its organic component removed
Types of Cells in Osseous Tissue
Osteogenic cells
1.


Unspecialized stem cell
Only cell to go through
cell division
Osteoblasts
2.


Bone building
Synthesize collagen and
organic components
 http://www.youtube.com
/watch?v=78RBpWSOl08
Continued
Osteocytes
3.


Trapped osteoblasts
Maintain metabolism
Osteoclasts
4.


“Bone breaking”
Digests extracellular
matrix
•Here, we see a cartoon showing all 3 cell types. Osteoblasts and osteoclasts are indicated.
•Note the size of the osteoclast (compare it to the osteoblast), and note the ruffled border.
•Why is there a depression underneath the osteoclast?
•What is the name of the third cell type shown here?
•What do you think the greenish material represents?
Compact Bone
 Osteon
 All the “rings” of the
lamallae (dartboard)
 Central Canal
 Contain blood vessels but
do not connect layers of
bone
 Lamellae
 The “rings” of bone
 http://www.youtube.com
/watch?v=ylmanEGjRuY
Compact Bone
 Canaliculi
 Channels that connect the
rings
 Perforating Canal
 Contain blood vessels that
connect the layers of bone
Long Bone
Spongy Bone
 Is light
 Support and protect red
marrow
 Made up of trabeculae
 Have lamellae, osteocytes
(in the lacunae) and
canaliculi
 Why is spongy bone
essential to bone structure?
Bone Formation
http://www.youtube.com/watch?v=p-3PuLXp9Wg
Intramembranous
Ossification
Endochondral Ossification
 Osteoblasts secrete cellular
 Cartilage is replaced by
 Mineral salts are deposited
bone matrix
 Osteoclasts dissolve bone
tissue to make room for
the medullary cavity
 Trabeculae form to make
spongy bone and
periosteum is formed
Growth in Bone Length
 Occurs at the epiphyseal
plate
 Epiphyseal cartilage divides
to create more cartilage,
while the diaphyseal
cartilage is transformed
into bone.
 This increases the length of
the shaft.
Growth is complete
 When the epiphyseal line
appears
 What happens if the bone is
fractured?
Bone Remodeling
 Old bone is replaced by
new bone
 How?
 Is a normal process and
occurs throughout life
 Some triggers
Fractures
 Partial
 Incomplete break across the
bone
 Complete
 Complete break across the
bone
 Closed
 Bone does not break through
skin
 Open
 Broken bones protrude
through skin
Fractures
Fracture Repair
http://www.youtube.com/watch?v=qVougiCEgH8
**The new bone is easily detectable in X-ray’s because it forms
a “bulge” at the fracture site
Kevin Ware
 http://www.youtube.com
/watch?v=CUAMGrWiV6
w
Cleft Palate
 What is it?
 Why is surgery necessary
for a child born with cleft
palate?
 http://www.youtube.com
/watch?v=KIPL52wGu0Q
Calcium Homeostasis
 Bone acts as a buffer for the
blood calcium level
 How?
 Is this an example of
negative of positive
feedback?
Features of the Skull
 8 cranial bones and 14
facial bones
 Sutures
 Hold skull bones together
 Fontanels (soft spots)
 Unossified bone tissue
 Go through
intermembranous
ossification
Cranial Sutures
 Coronal suture
 Sagittal suture
 Lambdoid suture
 Squamous suture
Paranasal Sinuses
 Produce mucus
 Serve to resonate an echo
 Give us our singing and
speaking voices
 Lighten the skull
The Hyoid Bone
 Does not attach to any
other bone
 Suspended from the styloid
process
 How?
 Supports tongue and
provides a place for muscle
attachement
The Human Skeleton
Division of Skeletal System
 Axial skeleton
 For protection and support
 Includes the skull, vertebral
column, and rib cage.
 Appendicular skeleton
 Used for movement
 Includes all other bones
The Vertebrae
Functions:
1. Movement
2. Protects spinal cord
3. Attachment for ribs and
muscles
Cervical Vertebrae
 Have 3 foramen
 Spinous process is split
 Atlas (C1)
 How?
 Axis (C2)
 How?
Thoracic Vertebrae
 Have facets to articulate
(connect) with the ribs
Lumbar Vertebrae
 Large and strong to
support the more weight
 Projections are short and
thick
Ribs
 Costal cartilage
 Hyaline cartilage
 True ribs vs false ribs
 Floating ribs
Bone Modification K-W-L Chart
What I Know
What I Want to know
What I Learned
Bone Modifications
http://www.youtube.com/watch?v=RfDy-uebGgg
 http://www.youtube.com/watch?v=1Pnf1S8uhNg

Bone Modifications
Modification
Bone
Stretching
Neck
Stretching
Chinese
Foot
Binding
Removing
Ribs
Description
Most
common
in
How it is
done
Reasoning
Complications