CH 6 Skeletal System
Part I
Fun Bone Facts
• When you were born you had over 300 bones. Now,
you have 206 bones.
• Over half the body's bones are in the hands and feet.
• The only jointless bone in your body is the hyoid bone
in your throat.
• As your bones grow, you get taller (of course). Your
growth in height is likely to stop by the time you are 16
if you're a girl and 18 if you're a boy.
• Your bones are 50% water and 50% solid matter.
• The smallest bone in the body is the stirrup (stapes) in
the ear measuring about 3 mm in length.
• The longest bone in the body is the femur.
Bone
• Osteology- The study of bone structure and the
treatment of bone disorders
Bone Functions:
• Support- Provides points of attachment for muscle and other
soft tissues
• Protection- Protects organs from injury
• Body Movement- As muscles contract, they pull and move
bones
• Stores Minerals- Especially calcium and phosphorous- When
minerals are in demand by the body, they are released from
bones to the bloodstream for distribution
• Stores Chemical Energy- Yellow bone marrow is found in
certain bones and contains adipocytes. This stored fat can be
used for energy
– Newborns do not have yellow bone marrow- just red bone
marrow
• Produces blood cells- Red bone marrow in certain bones
produces all red blood cells, white blood cells and platelets.
This process is called hematopoiesis
– Red bone marrow is found in adults at the pelvis, ribs,
sternum, vertebrae, skull and the ends of arm and thigh
bones
Though once used in various preparations, bone marrow has
fallen out of favor as a food in the United States; However
many other countries still feast on it. Diners in the US in the
18th century used a marrow scoop (or marrow spoon), often
of silver and with a long thin bowl, as a table implement for
removing marrow from a bone.
“Bone” Appétit!!
Parts of a Long Bone
• Bones are either long, short, flat or irregular. Their
shape is relative to their function.
• Examples of long bones include the femur,
humerus, tibia, fibula, radius and ulna.
• The parts of a long bone are:
• Diaphysis – The shaft of the bone (longest section)
• Epiphyses – The distal and proximal ends of bones
• Metaphyses- The 2 regions in a bone where the diaphysis
meets the epiphyses
• Each includes an epiphyseal plate (growth plate) made
up of hyaline cartilage. This is where bones elongate.
• Articular cartilage- Thin layer of hyaline cartilage
covering the epiphyses. This is where the bone
forms a joint with another bone.
• Medullary cavity- Space within the diaphysis that
contains yellow bone marrow in adults.
• Endosteum- Lining of the medullary cavity that
contains bone forming cells
• Periosteum- Tough outer membrane that surrounds
the bone surface where cartilage is not present.
• Compact bone- Layer of the diaphysis inside the
periosteum that gives bone its strength
• Spongy bone- A lattice work of bone material that
has many air spaces. Stores red bone marrow. The
thin columns of spongy bone are called trabeculae
Pop Quiz
1. What is the tough outer layer of a long
bone?
2. What are the ends of long bone covered
with?
3. What is the shaft of the bone called?
4. What material is found in the medullary
cavity?
5. What does hematopoesis mean?
Bone Cells
• The formation of mature bone cells is as follows:
Osteogenic cells
Osteoblasts
Osteocytes
• Osteogenic cells undergo cell division in the inner
portion of the periosteum and endosteum
• Osteoblasts are developed osteogenic cells that do
not have the ability to divide. They secrete
collagen- gives bone some flexibility.
• Osteocytes are mature bone cells that are trapped
in collagen (matrix) and perform the daily
metabolic activities of the bone.
Microscopic Structure of Compact Bone
• Perforating Canals (Volkmann’s Canals)Tunnels that extend transversely across the
width of bones. These canals carry blood
vessels and nerves.
• Haversian Canals- Tunnels that run
lengthwise through bone and connect with
Perforating Canals
• Lamellae- Concentric circles of hard,
mineralized matrix (collagen strengthened
with calcium and phosphorus)
• Lacunnae- Spaces between lamellae which
contain osteocytes
Structure of compact bone
continued…
• Canaliculi- Channels projecting outward
from lacunnae. These channels connect
lacunnae with each other. This allows
many routes for nutrients and oxygen to
reach bone cells.
• Osteon- Each Haversian canal with its
surrounding lamellae, lacunnae,
osteocytes and canaliculi
ANOTHER POP QUIZ….
1. What are the repeating circular units found
in bone tissue called?
2. What is in the center of an osteon?
3. What two things are found that run through
#2?
4. What are bone cells called?
5. Where are they found (the space)?
6. What is bone matrix composed of?
ANOTHER POP QUIZ….
1. What are the repeating circular units found in
bone tissue called? Osteon/Haversian system
2. What is in the center of an osteon?
Haversian/central canal
3. What two things are found that run through #2?
Blood vessel/nerve fibers
4. What are bone cells called? osteocytes
5. Where are they found (the space)? lacunae
6. What is bone matrix composed of? Collagen and
minerals like calcium and phosphorus
Bone Formation
• The process by which bone forms is called
ossification. This begins during the 6th or 7th
month of fetal development and continues
throughout adulthood.
• During ossification, hyaline cartilage becomes
bone. This happens by the following steps:
1. A membrane develops around the cartilage
called the perichondrium (This eventually
become the periosteum).
2. Chondrocytes (cartilage cells) trigger the uptake
of calcium.
Ossification continued…
3. Chondrocytes die because they can’t receive
nutrients through the calcified matrix.
4. Osteogenic cells in the perichondrium develop
into osteoblasts and ultimately osteocytes.
5. This continues until the hyaline cartilage of the
epiphyseal plate is completely replaced with
bone. The new bone in this area is called the
epiphyseal line.
Bone Surface Markings
• The markings on bones serve as sites of
attachment for muscles and/or ligaments.
• Openings in bones serve as passageways for
blood vessels and/or nerves.
• Projections on bones take part in forming joints.
Trochanter
A trochanter is a smooth,
rounded projection
Femur
Spine
A spine is a sharp,
slender, often pointed
projection
Fossa - a surface depression or concavity
Facet
A facet is a small, flat
surface
Condyle
Condyle – a large,
convex projection that
usually contacts another
bone
Fissure
A fissure is a deep
cleft between
adjacent parts of
bone
Meatus
A meatus is a
canal within a bone
Foramen
A foramen is a
natural opening
on a bone surface
Tubercle – rough, rounded projection
Suture
A suture is a line at the
junction of bones in the
skull
Sinus
- a hollow space within bone
Fractures
• What is a fracture?
A break in a bone
• What are the main types of fractures?
• Displaced- The bone snaps into two or more parts
and moves so that the two ends are not lined up
straight
• Non-displaced- The bone cracks either part or all
of the way through, but maintains its proper
alignment.
• Open(Also called compound) - Breaks through the
skin
• Closed (Also called simple)- Does not break
through the skin
• Multiple fracture- More than one fracture
occurs in the same bone
• Greenstick fracture- Closed fracture where
the bone is not completely broken into 2
pieces
• Comminuted fracture- The bone is broken
into several smaller pieces
• Spiral fracture- One or more parts of the
fractured bone has/have been twisted
• Impacted (buckle) fracture- The ends of the
bone are driven in to each other
• Transverse fracture- A break at a right angle
to the length of the bone
Organization of the Skeleton
•
•
The adult human skeleton has 206 bones.
The skeleton can be divided into…
•
•
Axial skeleton – Includes the bones of the skull,
ear, hyoid, vertebral column, ribs and sternum
Appendicular skeleton- Includes the bones of the
upper and lower limbs, pectoral girdle and pelvic
girdle
–
What is a girdle? Appendicular bone that connects to the
axial skeleton
Appendicular
Skeleton
Types of Joints
• Joints are either immovable, semimovable or movable.
• Immovable joints- The joints of the skull
are an example of this. It is important that
these joints don’t move so that they
protect the brain.
• Semi-movable joints- The joints of the
backbone are an example of this. They
have limited movement, but can allow us
to touch our toes.
Moveable Joints
• Ball and Socket- The shoulder- This joint
allows for a full range of motion.
• Hinge- The elbow and knee- This joint allows
for extension, but no rotation.
• Pivot- Where the top vertebra joins with the
skull. This allows us to move our heads as to
say “no”.
• Saddle- Base of the thumb- This allows for a
wide range of movement.
• Gliding- Bones of the hands and feet- Bones
can slide or twist against each other.
Skull
• The skull contains 22 bones
– 8 cranial bones
– 14 facial bones
• Skull bones are held together by immovable joints
called sutures:
• Coronal suture- Unites the frontal bone with the 2
parietal bones
• Sagittal suture- Unites the 2 parietal bones
• Lambdoid suture- Unites the parietal bones to the
occipital bone
• Squamous suture- Unites the parietal bones to
the temporal bones
Cranial Bones
• The 8 cranial bones are as follows:
Frontal bone, 2 Parietal bones, 2 Temporal
bones, Occipital bone, Sphenoid bone,
Ethmoid bone
* Color these on the picture and label the
sutures
Facial bones
• You need to be able to identify the
following facial bones:
Maxillae, Mandible, Nasal, Palatine,
Zygomatic, Lacrimal, Vomer
* Color these on the picture
Sinuses
• A hollow in a bone
• Function in producing mucus (trap infection) and
acting as resonating chambers for our speaking
and singing.
• Sinuses are continuous with the nasal cavity;
therefore, infection in the nasal cavity can travel
to the sinuses and cause membranes of the
sinuses to become inflammed.
• The 4 paranasal sinuses are: Frontal sinus,
Sphenoid sinus, Ethmoid sinus, and Maxillary
sinus
Hyoid Bone
• The hyoid bone does not attach to any other bone.
It is suspended by ligaments and muscles.
• The hyoid bone is in the neck between the mandible
and larynx (voice box).
• It is often fractured during strangulation.
• It supports the tongue and provides attachment sites
for tongue and neck muscles.
Vertebral Column
• The vertebral column extends from the skull to
the pelvis
• It protects the spinal cord and provides
attachment sites for ribs and back muscles
• It is composed of 26 vertebrae separated by
intervertebral disks of cartilage
• There are 5 vertebral regions: Cervical (7
vertebrae), Thoracic (12 vertebrae), Lumbar (5
vertebrae), Sacrum (5 fused vertebrae = 1
bone), and Coccyx (1 bone)
Typical vertebra
• A typical vertebra consists of a body and a vertebral arch
that surrounds the spinal cord
• The open part is the vertebral foramen through which the
spinal cord runs
• Vertebral processes (projections) are where muscles
attach. When you feel your backbone, you are feeling the
spines of the vertebra.
Vertebral Arch
Vertebral
Foramen
Cervical Vertebrae (C1-C7)
• The top 2 cervical vertebrae are considerably different
than the other 5.
• Atlas (first vertebra – C1) supports and balances the
head
• Axis- second vertebra- C2
• Odontoid process – projection of the axis that provides
a pivot for the atlas
Odontoid Process
THORAX
• The skeletal part of the thorax is called the
thoracic cage which includes the sternum, costal
cartilages, and ribs.
• The sternum is divided into the upper part
(manubrium), middle part (body) and lower part
(xiphoid process)
• The manubrium attaches the 1st and 2nd ribs
• The body attaches the 3rd through 10th ribs
• The xiphoid process does not attach any ribs
only abdominal muscles.
THORAX continued…
• There are 12 sets of ribs.
• Each rib attaches posteriorly with its
corresponding thoracic vertebra (Rib pair #1
attaches to T1).
• The first 7 ribs attach anteriorly to the sternum by
costal cartilage. These are true ribs.
• The costal cartilage of ribs 8-10 does not attach
to the sternum but to the cartilage of rib 7. They
are called false ribs.
• The costal cartilage of the 11th and 12th pairs
does not attach to anything; therefore, they are
called floating ribs.
PECTORAL GIRDLE
• The pectoral girdle attaches the upper limbs to the
axial skeleton.
• It includes the clavicle and scapula.
• The clavicle (collarbone) attaches to the
manubrium of the sternum and the acromion of the
scapula
• The scapula (shoulder blade) has 5 parts:
•
•
•
•
•
Acromion- High point of the shoulder
Body- Flattened triangular part
Spine- Runs diagonally across the body
Glenoid cavity- Depression where the humerus fits
Coracoid process- Where muscles and ligaments attach
UPPER LIMB
• Each upper limb consists of 30 bones: 1
humerus, 1 ulna, 1 radius, 8 carpals, 5
metacarpals and 14 phalanges
– Humerus:
• Proximal end articulates (is in contact) with
the Glenoid cavity of the scapula
• The body contains a “v” shaped area called
the deltoid tuberosity which is where the
deltoid muscle attaches
• The distal end has a rounded knob called
the capitulum that articulates with the
radius. Also is the trochlea that articulates
with the ulna.
UPPER LIMB continued…
– Ulna-
• On the medial side (pinky side) of the
forearm (in anatomical position).
• At the proximal end, the olecranon forms
the elbow.
• The trochlear notch is a concavity in the
bone where the trochlea rests.
– Radius• On the lateral side (thumb side) of the forearm
• Has a raised, roughened area called the
radial tuberosity- where the biceps muscle
attaches.
UPPER LIMB continued……
• Carpals– There are 8 carpal bones on each hand. They are
organized into 2 rows of 4 bones.
– Carpal bones include: scaphoid, lunate, triquetrum,
pisiform, trapezium, trapezoid, capitate, & hamate.
– These bones and the connective tissue that holds
them together create a tunnel called the carpal
tunnel. The median nerve runs through this tunnel.
As the joints of the wrist are overworked, they
become inflamed. This puts pressure on the
median nerve and is painful…..called carpal tunnel
syndrome.
UPPER LIMB continued……
• Metacarpals• Located between the fingers and wrist.
• There are 5 bones and are named 1st-5th
metacarpal. The 1st is the thumb’s
metacarpal.
• Phalanges• There are 14 on each hand (each finger has 3
and the thumb has 2)
• They are named 1st-5th proximal, intermediate
and distal phalanges.
Label & color the hand bones
Lower Limb
• The 2 lower lower limbs are each
composed of 30 bones:
– Femur, patella, tibia, fibula, 7 tarsals, 5
metatarsals, and 14 phalanges.
– Femur is the longest, strongest and heaviest
bone in the body.
– The distal end expands into the medial and
lateral condyle which articulate with the tibia.
– The patella (kneecap) is a triangular bone in
front of the joint between the femur and tibia.
It functions in protecting that joint.
Lower Limb continued….
• The tibia (shin bone) is the larger, medial
bone of the lower leg.
– Its proximal end expands into a lateral and
medial condyle which articulate with the
femur.
– On the anterior surface is the tibial tuberosity
where the patellar tendon attaches.
– On the distal, medial surface is the medial
malleolus which articulates with the talus of
the ankle and can be felt as a projection of the
medial surface of the ankle.
Lower Limb continued….
• The fibula is parallel and lateral to the tibia.
– The head of the fibula articulates with the lateral
condyle of the tibia
– The distal end of the fibula is the lateral malleolus
which articulates with the talus.
– The distal end also articulates with the tibia at the
fibular notch
• The ankle bones are called tarsals.
• These bones include the calcaneus, talus, cuboid,
navicular and the 1st, 2nd, and 3rd cuneiforms.
• Each foot contains 5 metatarsals and 14 phalanges.
The big toe has 2 while the other toes have 3.
Anatomy of the Knee
• A joint is a place where 2 bones meet.
• The knee is the largest and most frequently injured
joint of the body. It is an example of a hinge joint.
• The bones that form the knee joint are the femur,
tibia, fibula and patella. They are held together by
ligaments.
• The ends of the femur and tibia and the back of the
patella are covered with articular cartilage.
• In between the femur and tibia there are also 2
pieces of cartilage that cushion and absorb shock
during motion. These are called the medial
meniscus and lateral meniscus.
• Medial Collateral Ligament (MCL)- This runs along the
inside of the femur and tibia. It limits any joint
movement to the inside.
• Lateral Collateral Ligament (LCL)- This runs along the
outside of the femur and fibula. This limits any joint
movement to the outside.
• Anterior Cruciate Ligament (ACL)- This is called
cruciate because it crosses with the PCL. The ACL
attaches the front of the tibia with the back of the
femur. This limits the tibia from moving forward.
• Posterior Cruciate Ligament (PCL)- This attaches the
back of the tibia with the front of the femur. The PCL
limits the tibia from moving backward.
Types of Joints
• Joints are either immovable, semimovable or movable.
• Immovable joints- The joints of the skull
are an example of this. It is important that
these joints don’t move so that they
protect the brain.
• Semi-movable joints- The joints of the
backbone are an example of this. They
have limited movement, but can allow us
to touch our toes.
Moveable Joints
• Ball and Socket- The shoulder- This joint
allows for a full range of motion.
• Hinge- The elbow and knee- This joint allows
for extension, but no rotation.
• Pivot- Where the atlas and axis join together.
This allows us to move our heads as to say
“no”.
• Saddle- Base of the thumb- This allows for a
wide range of movement.
• Gliding- Bones of the hands and feet- Bones
can slide or twist against each other.
Fractures
• What is a fracture?
A break in a bone
• What are the main types of fractures?
• Displaced- The bone snaps into two or more parts
and moves so that the two ends are not lined up
straight
• Non-displaced- The bone cracks either part or all
of the way through, but maintains its proper
alignment.
• Open(Also called compound) - Breaks through the
skin
• Closed (Also called simple)- Does not break
through the skin
Common Types of Fractures
• Multiple fracture- More than one fracture
occurs in the same bone.
• Greenstick fracture- Closed fracture where
the bone is not completely broken into 2 or
more pieces.
• Comminuted fracture- The bone is broken
into several smaller pieces
• Spiral fracture- One or more parts of the
fractured bone has/have been twisted
Let’s see what you remember 
1.
2.
3.
4.
5.
What is the long shaft of a bone?
What is hematopoiesis?
Where does hematopoiesis occur?
What is the space within the diaphysis?
What is the tough outer membrane of the
diaphysis?
6. Where is the epiphyseal plate located?
7. What are the cells of bone that divide to
produce new bone cells?
8. What are mature bone cells?
9. What is the membrane that surrounds the
epiphyseal plate during ossification?
10. Where are osteocytes found in long
bone?
11. What are mineral rings of long bone?
12. What are small channels that run
through bone and connect lacunnae?
13. What is a smooth, rounded projection of
bone?
14. What is a projection of bone that is in
contact with another bone?
15. What is a small, flat surface on bone?
16. What is a natural opening in bone?
17. What unites the parietal bones with the
occipital bone?
18. What is the cheekbone?
19. What are the 5 vertebral regions from
top to bottom?
20. To what part of the sternum does the
clavicle attach?
21. What is the C1 vertebra? C2?
22. What rib pairs are the false ribs?
23. What part of the ulna forms the elbow?
ACL Repair Video
http://www.orlive.com/akronchildrens/videos/
arthroscopic-surgery-to-replace-a-youngathlete-s-acl?view=displaypageNLM
GOOD LUCK ON YOUR
TEST!!!