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LEARNING OBJECTIVES
- Read the Class Notes, using the Textbook
illustrations to help understand the concepts. Read the chapter using the
Class Notes as your guide. There are many questions included
to help tie the systems and concepts together into an integrated,
holistic understanding of anatomy and physiology.
- Take the
Ch.
6 self test in the online textbook.
DO NOT EMAIL THIS TEST TO YOUR INSTRUCTOR. It is a learning tool
only. These tests will also include
questions that are NOT covered in this course.
- Use any resources on the
Online Textbook,
to integrate your learning.
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Chapter 6. Skeleton system
Use the diagrams in the book to enhance
comprehension of these concepts.
Describe the functions of the skeleton
Support - bones provide a rigid structure to which
the soft tissues are attached.
This structure holds the soft tissues in place,
relative to one another.
Leverage - muscles move bones, which then causes movement of a body
part,
such as arms and legs.
Storage:
nutrients - Ca, P
energy - lipids in Yellow Marrow
Hemopoiesis - Blood formation - in Red Marrow
Protection of vital organs:
Brain and spinal cord
Lungs
The skeletal system is a type of Connective Tissue.
What type of CT is it?
Support or Structural CT.
What are the matrix components?
Ca and P with some collagen.
What are the functions of the skeletal system that are supported by the
Matrix?
Support, leverage, and protection
What role does Ca and P play in the functions of the skeletal system?
The 'bone salts' form the crystalline matrix that
produces the solid structure.
What role does Collagen play in the functions of the skeletal system?
Collagen, a molecule with great strength but flexible
allows bones to flex a bit, while remaining 'solid'.
What are osteocytes? Remember, the name ends in '-cyte'.
It is a MATURE bone cell.
What is its function?
How about osteoblasts and osteoclasts?
Explain how bones are classified and give an example of
each
3 methods: 1) Shape, 2) type of tissue, and 3) type of ossification
1. Shape
What are the four shapes of bones?
Give an example of each shape.
Long bone - any bone that is longer than wide or thick
- femur, radius, ulna, tibia, fibula
Short bone - any bone that is equal in width, length, and thick
-carpals and tarsals
Irregular shape bone -any bone that has 'wings, processes, etc'
that give the
bone an irregular shape
- vertebra
Flat bone - bone that is formed through INTRAMEMBRANOUS
OSSIFICATION
often has a 'flat'
appearance.
- bones of the skull: parietal, occipital,
frontal
- scapula, clavicle
- bones of the ribcage - Ribs look like
LONG bones, but they form
inside
membranes and are therefore FLAT bones
2. Bone tissue
a. compact bone. - The function is COMPRESSION STRENGTH i.e.
bone can resist being compressed. The functional UNIT of compact
bone is the OSTEON
Osteons are made up of a:
- central canal surrounded by
- lamellae (layers) of bone salts, with
- osteocytes embedded in lacuna. The Osteocytes are connected to the
central canal by
- canaliculi.
b.
Spongy (cancellous) bone – The function is 'light weight'.
It is bone
tissue made up of a network
of TRABECULAE, which are
the functional units of spongy bone.
Trabeculae are rods/plates of bone that are
connected to one another and to the
wall with spaces between the trabeculae.
The
spaces are filled with bone marrow.
Describe bone marrow
Red bone marrow - in spongy bone. The site of
hemopoiesis.
Yellow marrow - medullary cavity. Stores of Lipids.
How is compact bone different from spongy bone?
Make a table for compare and contrast of compact
and spongy bone.
What is the functional unit of compact bone?
What characteristic does the osteon give to
compact bone?
What is the functional unit of spongy bone?
What characteristic do trabeculae give to spongy
bone?
3. Ossification method. - two types
- Intramembranous ossification
– is the building of bone within a
membrane.
- Endochondral ossification
– is the formation of a hyaline cartilage
model first and then replacing the cartilage of the model with bone
salts. I.e build a model first then build the bone based on the model.
This is like building a PLASTIC model first, then
removing a small piece of plastic, replacing that with metal, then
removing another small piece of plastic - replacing it with metal, then
remove another piece of plastic - replace with metal... and so on, til
the entire plastic model has been replaced with metal.
Describe how the embryonic skeleton is replaced by bone
This is ENDOCHONDRAL Ossification - replacement of a
cartilage model.
FIRST: Draw a ‘characteristic bone’ and label the parts.
Diaphysis
Compact bone
Epiphysis
Spongy bone
Marrow (which color?)
Epiphyseal plate & Epiphyseal line
Medulary cavity
Marrow cavity (which color?)
Periosteum
Endosteum
Primary ossification center
Secondary ossification center
Use this to describe ‘endochondral ossification’.
What is the epiphyseal plate?
AKA the growth plate, it is a region between the
diaphysis and epiphysis made of hyaline
cartilage. Remember chondroclasts, chondroblasts
and osteoblasts?
NOW- remember, you are describing the REPLACEMENT of a
cartilage model, with bone salts. You start with a model of the
bone, made out of hyaline cartilage. Chondroclasts remove a
cartilage molecule which OSTEOBLASTS replace with a hydroxyapatite
molecule.
Where is the primary ossification center?
This is the center of the diaphysis - where osteoblasts first put bone
salts to build compact bone..
Where is the secondary ossification center?
This is in the epiphysis - where osteoblasts start building
spongy bone.
What happens to the epiphyseal plates as the bone grows
longer?
They move (grow) farther apart. Your femur was only about 5 inches
long when you were born. It is now 15 inches or longer.
When does a bone STOP growing longer?
When the epiphyseal plate 'closes', i.e. becomes completely ossified,
i.e. the hyaline cartilage is completely replaced by bone salts.
Why?
There is NO MORE cartilage to replace with bone salts -
What happens to the epiphyseal plate that causes the bone
to stop growing longer?
What is the epiphyseal plate called after this event?
Epiphyseal LINE. When you see an epiphyseal LINE, you
know that person is mature, and
is not going to grow any taller.
The epiphyseal plate closes in females at about age 17, and in
males at about age 20.
Males grow for another 3 years - and their bones are
longer, therefore, males are usually
taller than females.
Occasionally, a child will 'damage' his growth plate.
The epiphyseal plate will 'close' due to the damage - resulting in
'short' limb.
State the nutrients necessary for bone growth
Hydroxyapatite - forms the crystalline matrix
that makes bone a solid
Ca++ (cation) is the most abundant
mineral in the body
P+ (cation)
Vitamin C - formation of collagen; Scurvy is a disease
resulting from a deficiency of
Vitamin C. Bones do not have
enough collagen and become too brittle (break easily).
What does collagen do for bones?
Vitamin D - Absorption of Ca from the diet. Rickets is a
disease resulting from a deficiency of
Vitamin D. Bones do not have
enough hydroxyapatite and become too flexible (can't
support
weight, and are bendable).
Bowlegs
What does hydroxyapatite do for
bones?
Vitamin A - used by osteoclasts in removal of bone salts from the
crystalline matrix.
Name the hormones involved in bone growth and
maintenance
Calcitonin - tells Osteoblast to build bone, put
Ca++ into bone. (Reduces blood
Ca++ concentration).
PTH - parathyroid hormone - tells Osteoclast to remove Ca from
bone. (increase
blood Ca++ concentration).
Thyroxine - regulates growth
HGH - human growth hormone- regulates growth
Estrogen, Progesterone, Testosterone - stimulate growth at
puberty, osteoporosis at menopause
Calcitriol - Ca++ absorption from food
Explain what is meant by exercise for bones and explain
its importance
Exercise – lifting weights, walking, running, whatever –
places mechanical STRESS on the bones involved in the movement. Your
body responds by making the bone stronger so that next time it is
stressed, the bone will be able to withstand more stress.
How does the bone become stronger?
By increasing the density of the hydroxyapatite in the crystalline
matrix. In so doing, the bone becomes thicker, too.
Exercise increases the size and strength of muscles - which are attached
to bone by collagen fibers. These points of attachment also become
bigger with more collagen anchored into the bone matrix.
How is this related to ‘bone remodeling’?
Remember, osteocytes (controlled by Calcitonin and PTH) are continually
adding and removing Ca++ molecules (to maintain blood Ca++
concentration). Exercise causes an increase in Calcitonin
stimulation of osteoblast activity - which causes increased
hydroxyapatite formation.
What is ‘bone remodeling’?
The constant removal and placement of bone salts in the crystalline
matrix.
When does bone remodeling occur?
Every moment of every day, through out life.
When you STOP exercising, your body senses this, and starts removing
bone matrix. This makes the bone 'weaker', but also means that you
need less energy to move the body.
How does this produce the differences between male and
female skeletons?
Males have bigger, stronger muscles, and therefore, bigger stronger
bones.
What is the covering around a bone called?
What type tissue is this covering?
It is basically a
‘capsule’
– what type tissue makes up a capsule?
The Periosteum is very vascular. Blood
vessels/capillaries in the periosteum enter the Central Canal of the
osteons, and supply nutrients to the osteocytes and remove wastes.
Remember, bone repair is much easier than cartilage repair - due to the
extensive blood supply to bone, through the central canal.
What type protein fiber is found in this covering?
To what is it attached in the bone?
Remember there are collagen fibers embedded in the hydroxyapatite.
What is the function of a tendon?
Attach Muscles to bone.
Tendons are NOT stretchable - therefore ALL the energy used for
muscle contraction
produces the maximum movement.
What is the function of a ligament?
Attache bones to bones.
Moderately stretchable. Gives some flexibility to
joints and prevents damage
(sprained joints, torn
tissues, etc).
What type of tissue is a ligament or tendon?
Regular Dense CT.
How is the ligament/tendon actually connected to the
bone?
Remember the periosteum is Irregular DCT, made of
collagen fibers. This capsule is
anchored to the bone by collagen fibers
embedded in the capsule and in the
hydroxyapatite. Collagen fibers that
make up the tendon/ligament are embedded also
in the capsule and in the bone.
What is the function of the bone structures such as
spine, process, crest, line, ridge, etc?
These are points of attachment for tendons/ligaments.
The Styloid process on the bottom of the skull anchors the
muscles that control the neck,
tongue, and swallowing.
The Mastoid Process on the bottom of the temporal bone
(just below and behind the ear)
anchors the sternocleidomastoid
muscle - which allows you to move your head.
The Iliac Crest on top of the Ilium (pelvic girdle)
anchors the abdominal muscles and lower
back muscles.
The Spinous processes of the vertebra anchor the
ligaments that attach the ribs, and the
back muscles.
The Occipital crest on the occipital bone, anchors the
trapezius muscle and holds the
head upright.
What is the function of a hole in the bone?
Other things such as nerves, blood vessels, etc pass
through holes :-)
What are general terms for a hole in a bone?
Foramen (singular), foramina (plural)
Meatus
The Foramen Magnum is the large hole in the
occipital bone (cranial bone) through
which the spinal cord exits the cranial
cavity.
The olfactory foramina located in the cribiform plate of the
ethmoid bone, allow the olfactory
sensory nerve endings into the top of the nasal
cavity - to the olfactory epithelium.
The SELLA TURCICA is a depression in the sphenoid
bone which houses the pituitary
gland.
Identify the two major subdivisions of the skeleton and
list the bones in each area
Axial - vertebral column and the structures
attached to it: cranium and ribcage
This is the AXIS. It anchors the
limbs, so that they can move effectively.
Appendicular - the girdles and limbs
Pectoral girdle - clavicles, scapulas, arms
Pelvic girdle - pelvic bones and legs
Why is the axial skeleton called the axis?
What is the function of the pectoral and pelvic girdles?
What are the sections of the vertebral column called?
Cervical - neck. 7 vertebra. C1, C2,
... C6, C7
Thoracic - rib cage. 12 vertebra. T1, T2,... T11, T12
Lumbar - lower back. 5 vertebra. L1 - L5
Sacral - 5 fused into one solid bone. provides a solid support and
point of attachment of the pelvic girdle to
the axial skeleton.
Coccyx - tail bone. 3-5 usually fused together in adults.
How are the vertebrae in each section named?
The vertebra in each section are named after that section. C1... C6
for cervical vertebra, and so on.
Most humans have 12 pairs of ribs.
How many thoracic vertebra are there?
Why are thoracic vertebra named 'thoracic'?
Explain how joints are classified; give an example of
each and describe the movements possible
There are three types of JOINTS between bones. Here, I
will classify them according to the flexibility (movement) of the joint.
The flexibility of the joint determines the strength of the joint.
Synarthrosis - (syn=no; arthrosis=
articulation= movement)
NON moveable joint, no flexibility.
VERY STRONG
Sutures between the skull bones
Amphiarthrosis - (amphi=some)
limiited movement, limited flexibility
moderately strong
pubic symphisis, intervertebral joints
Diarthrosis - (di= much) AKA
SYNOVIAL JOINT
LOTS of movement, Most flexible type of joint
WEAK (compared to the synarthroses)
90% of the joints in the body:
knees, elbows, knuckles of feet and hands,
temperomandibular joint, shoulder, hips
The SHOULDER is the most flexible
joint in the body - but also the weakest. It has
widest range of movement,
but is the most commonly dislocated.
What are the joints between the cranial bones called?
Are they moveable or not?
What are the joints between the vertebra called?
Flexible?
What is the joint between the two pubic bones called?
Flexible?
What are joints between the femur and the pelvic girdle
called?
What are the joints between the humerus and the pectoral girdle called?
What are the joints between the humerus and the radius
or ulna called?
What are the joints between the carpals, metacarpals,
phalanges, etc?
Which is the most common type of joint?
Why?
The ability to move is extremely important for survival. The
ability to move to find food and eat, move toward a mate, away from
danger, etc.
Which joint in the body is the weakest (the most commonly dislocated)?
Which joint in
the body is the strongest (most inflexible)?
What is the advantage of a strong joint?
The sutures between the skull bones of a fetus are LOOSE.
This allows the fetus head to squeeze through the birth canal.
Later, the sutures fuse and form a SHELL around the brain.
What is the
advantage of a moderately moveable joint?
Moderately moveable joints, such as the pubic
symphisis and intervertebral joints, allow these joints to flex a little
bit, allowing enough movement to absorb shock and prevent damage to the
adjacent tissues. The symphisis pubis also flexes a bit during
child birth.
Describe the parts of a synovial joint and explain their
function
What do you gain with a synovial joint? (What is
the advantage?)
What do you lose with a synovial joint? (What is the
disadvantage?)
Define ‘articulation’. List the characteristics of an
articulation surface.
What type tissue is articular cartilage?
Hyaline cartilage - made up of hyaluronic acid - the very durable,
tough, matrix molecule.
Where do you find articular cartilage?
At the ends of long bones, where two or more bones rub together while
moving.
What is the main matrix molecule in articular
cartilage? (Ch. 4)
What is th function of a chondrocyte?
What is a ‘facet’? What is its function?
List some bones with facets.
Thoracic vertebra
List the bones that
articulate with those facets.
Other vertebra,
Ribs
What type tissue lines the facet?
Where
do you find articular cartilage?
What is
another name for articular cartilage?
Describe the differences between the male and female
skeleton.
Explain WHY the differences exist.
Review bone remodeling, exercise for bones, and attachment of
muscle to bone.
Review 'spine, process, crest, line, ridge, etc
How is the skull different?
Review 'spine, process, crest, line, ridge, etc
How is the pelvis different?
Sub-pubic angle
Angle of coccyx
Shape of the pubic opening
Height of the pelvic girdle
Width of the pelvic girdle
Why is the female pelvis wider with a larger
opening, than the male pelvis?
How are the ‘lines, ridges, processes, etc different?
How is this information used forensically?
How are the differences related to ‘exercise for bones’
and ‘bone remodeling’?
How does aging affect this system?
Menopause - osteoporosis
Old cells are less efficient - therefore osteocytes are less efficient
at maintaining bone.
Endocrine system is less efficient - therefore the hormones are less
efficient.
Less exercise means thinner, more fragile bones - more easily broken.
How does this system interact with the other systems?
Remember – all the systems have to work together to
maintain homeostasis.
How does the storage of Ca++ in bones affect nerve
signal transmission, muscle contraction and blood clotting? How does
this affect homeostasis?
LAB
Bones have various anatomical characteristics:
Elevations and projections: Process, ramus, trochanter,
tubercle, tuberosity, crest, line, and spine. These are points of
attachment for Ligaments and Tendons.
Holes and openings: foramen, canal
Recognize and Name the following structures:
Axial skeleton
Cranium
Parietal
Sagittal suture
Occipital
Lambdoidal suture
Frontal
Coronal suture
Temporal
Squamosal suture
Mastoid process of the temporal bone
Styloid process of the temporal bone
Zygomatic
Zygomatic arch
Maxilla
Mandible
Nasal
Lacrimal
Ethmoid
Cribiform plate of the ethmoid bone
Sphenoid
Sella turcica of the sphenoid bone
Recognize and Name the following holes in the skull
Foramen magnum
External auditory canal
Supraorbital foramen
Infraorbital foramen
Optic foramen
List the sinuses and give their function.
Hyoid bone
List the sections of the vertebral column
Name the vertebra in each section and how many vertebra
are in each section.
What is the transverse process? The spinous process?
What is the function of these structures?
What is the Atlas bone?
What is the Axis bone?
What are the structural differences between the
vertebrae of each section?
Describe the sacrum and coccyx.
List the parts of the rib cage.
List the parts of the sternum: manubrium, body, xyphoid
process
Costal cartilage.-
what type tissue is costal cartilage?
What are the floating ribs? Why are they called
‘floating’?
Appendicular Skeleton
Upper limbs:
Pectoral girdle
Clavicle
Scapula
Spine of scapula
Acromion process of scapula ( what
is the function of a ‘bone process’?)
Coracoid process of scapula
Glenoid cavity of scapula ( what
articulates with the glenoid cavity?)
Limb:
Humerus
Radius
Ulna
Carpals ( how
many are there?)
Metacarpals
phalanges
Lower limbs:
Pelvic girdle:
Pelvis
Coax
Ilium
Ischium
Pubis
Pubic symphysis (symphysis pubis)
What type of joint is the pubic symphysis? What type of
cartilage is it?
How do you distinguish a male pelvis from a female
pelvis? Why?
What is the function of the iliac crest? Where is it?
Limb:
Femur
Patella
Tibia
Fibula
Tarsals ( how
many are there?)
Metatarsals
Phalanges
Where is the linea aspera? What is its function?
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