Teaching
Notes
Articulations
Investigating motion and structure
Overview
Goal
This lesson uses the animation and measurement capabilities of NIH Image, along
with high resolution images from the Visible Man Project, to allow students to
investigate joint motion and joint structure.
Students will investigate joint
motion and structure using
animations and digital
photographs of frontal and
horizontal sections through the
major joints of the human
body.
The first section of the lesson is an exploration of joint motion. Rather than memorizing the definitions of joint motions, such as abduction or flexion, students view
movies of these motions to develop their own definitions. This is an excellent
opportunity for students to work in teams to cooperatively develop the definitions.
Topics
• Skeletal system
• Articulations
• Planes of section
Science Process Skills
• Observation
• Measurement
• Synthesis
In the second part of the lesson, students examine digital photographs of frontal,
sagittal and horizontal sections that transect the major joints of the human body. Joint
structures are identified and labeled on a second image to help students learn the
anatomy of these joints. By investigating the joints in context, embedded in their
surrounding structures, students gain practice interpreting sectional anatomy.
IPTechnique Sheets
• Stacks
• Measuring
• Memory
To infer the functional adaptation of joints, students measure the size of the intervertebral disks found within the intervertebral articulations and hypothesize a reason for
the differences. They also measure the difference in articular contact between
shoulder and hip joints to explore the relationship between joint strength and range
of motion.
Troubleshooting
Prior to starting this lesson, the NIH Image Undo and Clipboard buffer size should be
increased to at least 1080K to accomodate the large Frontal section image. See the
Memory IPTechnique Sheet for details about how to do this.
Objectives
Students will:
• animate and observe joint motions to develop definitions for each
• examine ten major joints in a frontal section of the human body to determine the
structural and functional classification of each
• analyze high resolution photographs and MRI’s of hip, knee and shoulder joints
to discover relationships between bones and surrounding soft tissues and relate
joint strength to range of motion
Prerequisites
Prior to this lesson, students should
• be able to apply terms of anatomical orientation
THE VISIBLE
HUMAN
PROJECTTM
• be able to identify the bones of the human body
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Articulations
99
Acknowledgments
Lesson developed by Paul Johnson, Deborah Alongi, and Sandy Zetlan.
The joint motion images were created by the authors with the help of our model, Jill
Manzo, and Work Production Services. The Visible Man images were obtained from
the National Library of Medicine and were modified and adapted for use in this lesson
by Paul Johnson.
Answers
1. Answers will vary. Typical answers are shown in the following table.
Joint Motion
Abduction
Movement of a bone away from the longitudinal axis of the body (or part of the
body such as one finger moving away from another) in the frontal plane.
Adduction
Movement of a bone towards the longitudinal axis of the body (or part of the
body such as one finger moving towards another) in the frontal plane.
Extension
Movement at a joint in which the angle between the two articulating bones
increases. Usually referring to movement in the anterior-posterior plane.
Flexion
Movement at a joint in which the angle between the two articulating bones
decreases. Usually referring to movement in the anterior-posterior plane.
Circumduction
Rotation
Hyperextension
Movement in which the distal end of a bone moves in a circle while the proximal
end at the joint remains stable. Usually referred to as combining extension,
flexion, abduction, and adduction.
Movement of a bone around its longitudinal axis.
Continuation of extension beyond anatomical position.
Inversion
Movement of the sole of the foot medially.
Eversion
Movement of the sole of the foot laterally.
Dorsiflexion
Movement of the ankle joint causing elevation of the foot.
Plantar flexion
Movement of the ankle joint causing elevation of the heel.
Protraction
Movement of part of the body (often the jaw or shoulders) anterior in the
horizontal plane.
Retraction
Movement of a part of the body (often the jaw or shoulders) posteriorly in a
horizontal plane.
Elevation
Depression
100
Definition of Joint Motion
Upward movement of part of the body (often the jaw or shoulders).
Downward movement of part of the body (often the jaw or shoulders).
Pronation
Movement of the palm posterior from the anatomical position, or downward.
Supination
Movement of the palm anteriorly into the anatomical position, or upward.
Opposition
Movement of the thumb towards the fingers in a grasping motion.
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2-6. Answers are shown below in Table 2.
#
Bone name
Bone name
Degree of
joint motion
Functional
classification
Structural
classification
1
parietal
parietal
immoveable
synarthrosis
fibrous
2
scapula
clavicle
freely moveable
diarthrosis
synovial
3
cervical vertebral
transverse process
cervical vertebral
transverse process
freely moveable
diarthrosis
synovial
4
cervical vertebra
body
cervical vertebral
body
semi-moveable
amphiarthrosis
cartilaginous
5
humerus
scapula
freely moveable
diarthrosis
synovial
6
lumbar vertebral
body
lumbar vertebral
body
semi-moveable
amphiarthrosis
cartilaginous
7
femur
hip bone
freely moveable
diarthrosis
synovial
8
pelvic bone
pelvic bone
semi-moveable
amphiarthrosis
cartilaginous
9
femur
tibia
freely moveable
diarthrosis
synovial
10
tarsal
tarsal
freely moveable
diarthrosis
synovial
7. Representative measurements are shown in Table 3 below.
Region of spine
Thickness of intervertebral discs, mm
Cervical (C3-4)
6.5
Upper thoracic (T3-4)
6.5
Lower thoracic (T9-10)
8.0
Upper lumbar (L1-2)
13.0
Lower lumbar (L3-4)
16.2
8. Answers will vary. Students should observe that the size of both the vertebral
bodies and the intervertebral discs vary over the course of the vertebral column
with the general trend being toward increasing size in the lower thoracic and
lumbar regions. Answers will vary depending upon measuring technique and
which intervertebral discs are measured. Measurement of the intervertebral
discs in the cervical, thoracic and lumbar spines reveals the disks in the cervical
and upper thoracic regions to be about the same size, but beginning in the lower
thoracic spine the intervertebral disks begin to get larger with the disks in the
lumber spine being 2 to 2.5 times larger.
9. Answers will vary. Students may hypothesize that the increased size of the
vertebrae and intervertebral disks in the lumbar spine is an adaptation to
increasing load on the lower spine due to the weight of the upper body.
10. Answers will vary. If the increase in lumbar disk size is due to the increase in
weight of the upper body carried in an upright posture, then four-legged
animals with horizontal vertebral columns should not show an increased intervertebral disk size in the lower spine.
11. Identification of the synovial joints is shown in Table 2.
12. Answers will vary. The presence of the patella in the lateral view, the shape of
the musculature in both views and the shape of the femur in the frontal view, all
give clues to the orientation of the leg in the images.
13. Answers will vary. The surfaces of the articulating bones are covered with
hyaline cartilage which appears lighter in color than bone.
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Articulations
101
14. The articular capsule surrounds and attaches to the bones of the joint. Ligaments
connecting the bones support and provide strength to the joint. Menisci and
bursa prevent joint friction, and cushion the bones of the joint.
15. Answers will vary. Some false color tables make it easier for the human eye to
detect differences in subtle shades of gray, making it easier to see details.
16-18. Answers will vary with technique used to make the angle measurements.
Representative answers are shown in Table 4 below.
Joint
Angle of articulation
Percent contact
Shoulder
64 degrees
18%
Hip
168 degrees
47%
19. Answers will vary. The shoulder joint is most easily disarticulated because the
head of the humerus is not very well enclosed by the glenoid fossa.
20. The articular capsule, ligaments joining bone to bone and tendons joining
muscle to bone help hold the joint together.
21. Representative answers are shown in Table 5 below.
Joint
Relative range of motion
Relative strength
Shoulder
high
low
Hip
medium-high
medium
Knee
low
high
22. Representative answers are shown in Table 5 above.
23.
102
Joints with greater strength have a more limited range of motion. Joints with a
high degree of range of motion have less strength.
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Lesson
Articulations
Investigating motion and structure
The points of contact that develop between bones, bones and cartilage, and
bones and teeth are called articulations, or joints. Our joints, in concert with
our muscles, allow us to walk, run, dance, lift loads and grasp objects. Without
joints, a skeleton would be rigid and movement would be impossible. However, not all joints permit movement. The bones of the adult skull do not move,
but the “jigsaw puzzle” nature of the individual bones allows the skull to
enlarge as the brain grows. Other joints, such as between the tibia and fibula,
allow only restricted movement. However, many joints, such as the shoulder,
allow a great deal of movement. In this lesson, you will explore the motion and
structure of the major moveable joints in the human body.
THE VISIBLE
HUMAN
PROJECTTM
The joint anatomy images in this
lesson are from the Visible
Human Project. The images are
digital photographs of frontal,
horizontal and sagittal sections
through the major joints of the
body.
What are the motions allowed by joints?
In this part of the lesson, you will view movies showing motions at different
moveable joints.
ì Open the folder Action movies. All of the files in the folder Action
movies are stacks of images which can be animated. Each folder in
Action movies illustrates a type of movement.
See the Stacks IPTechnique
Sheet for information on
animating stacks.
 File/Open…
ì Open the Abduction-adduction folder and then open Shoulder.
ì Animate Shoulder. This movie shows abduction and adduction at the
shoulder joint. Carefully observe the motion, the labels, and the
arrows. Use your own body to demonstrate the movement.
ì Close Shoulder (File/Close…).
ì Open, animate and study the other image files in the AbductionAdduction folder. (You will probably need to close each file before
opening the next one).
1. Use your observations of the animated motions to develop definitions
for abduction and adduction. Record your definitions in the Table 1 on
your Data Sheet.
ì Open and animate each movie in the folders in Action movies.
Develop your own definition for each type of motion listed in the table
on your Data Sheet. Each motion should have its own unique definition that cannot be confused with other motions.
Movement is more than skin deep
ì Open Frontal section. This is a frontal image of a human cadaver
that was sectioned and photographed as part of the Visible Human
Project.
ì Use the · tool to move the image so you can see the entire image from
top to bottom.
ì Use the ÿ tool to magnify the image to examine the structures more
closely. To reverse magnification, hold the æ key while clicking on
the image.
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 Stacks/Animate
Use the 1-9 keys to make the
animation faster or slower.
Click on the image to stop
the animation.
 If you use the > and < keys
to move through the stacks,
make sure you view the
motion starting with the first
slice and in ascending
numerical order.
Hint: As you create your
definitions, consider factors
such as the angle of articulating
bones, axis of rotation and the
plane in which the movement is
occurring. Check your definitions against those in your
textbook when finished.
 Frontal section is larger
(1078K) than the Undo
buffer default size (300K). If
you get a message to this
effect, change the Undo
buffer by choosing Options/Preferences… and
enter 1080 for size. Quit
and restart NIH Image for
your changes to take effect.
Articulations
103
ì Use your knowledge of the human body to locate examples of the four
main tissue types: muscle, nervous, epithelial, and connective.
ì Look for examples of the different types of connective tissue found in
and around joints: bone, cartilage, fat, and dense connective tissue
(tendons and ligaments).
ì Close Frontal section.
 File/Close…
What do you already know about joints?
ì Open Numbered frontal section.
 File/Open…
2. What are the names of the articulating bones at each joint? Enter your
answers Table 2 on your Data Sheet.
What are the functional classifications of joints?
Joints can be categorized functionally based on the degree of movement
allowed by the joint. As you evalauate their function, demonstrate how these
joints move in your own body, or refer back to the Action movies.
3. Based on your own experience, and your textbook, are the numbered
joints freely moveable, slightly moveable, or not moveable? Enter your
answers in Table 2.
Functional classification
• synarthrosis—immovable
• amphiarthrosis—slightly
movable
• diarthrosis—freely
movable
4. Using the table in the margin, enter the functional classification of the
joints in Table 2.
What are the structural classifications of joints?
Joints are also categorized structurally. The type of joint structure is determined by the type of soft connective tissue found between and around the
articulating bones. Soft connective tissues found around the joint include
dense fibrous connective tissue (ligaments) and cartilage. The three types of
structural joints are: fibrous joints, cartilaginous joints, and synovial
joints.
Fibrous joints bind the articulating structures tightly with ligaments. There
tends to be little or no movement at a fibrous joint.
5. What is the single fibrous joint in Numbered frontal section?
Enter the information in Table 2 on your Data Sheet.
Structural classification
• fibrous—contains dense
fibrous connective tissue
• cartilaginous—contains
hyaline cartilage, fibrocartilage, or elastic cartilage
• synovial—has a fluid filled
synovial capsule, often
containing accessory
ligaments
Cartilaginous joints contain cartilage between the articulating bones.
These joints allow only a little movement but provide a cushion against
impact. Carilaginous tissues are softened by the hormone relaxin during
pregnancy and childbirth.
6. Fill in the three cartilaginous joints found in Numbered frontal
section on Table 2.
Synovial joints are the third structural classification of joints. Synovial joints
are structurally complicated joints that allow significant joint movement. All
freely moving joints are synovial joints.
7. Identify the synovial joints found in Numbered frontal section and
complete Table 2 on your Data Sheet.
104
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Vertebral joint structure and function
In this section you will compare the thickness of the intervertebral discs along
the length of the vertebral column. Damage to these fibrocartilage joints can
result in a so-called “slipped disc”.
ì Open Intervertebral articulations. This image is a midsagittal
section through the vertebral column.
ì Use the ‡ tool to select the thickness of a disc within two of the
intervertebral joints in the cervical spine, as shown in the margin.
ì Measure the thickness of the disc. The scale on this image has been set
in millimeters (mm).
 Analyze/Measure and
Analyze/Show Results
ì Measure the thickness of two discs in the thoracic and lumbar regions.
See the Measuring
IPTechnique Sheet for extra
information on making measurements.
8. Record your measurements in Table 3 on your Data Sheet.
9. How do the intervertebral discs vary in thickness along the length of
the spine?
10. Hypothesize a reason for the variations of intervertebral disc width.
11. Do you think the same variations would occur in four-legged land or
marine mammals? Why or why not?
ì Close Intervertebral articulations.
Note: In four-legged animals,
the vertebral column is usually
carried horizontally (parallel to
the ground) rather than vertically, as in humans.
Knees in detail
ì Open Knee-hip. This image shows two views of the synovial knee
and hip joints from the same individual.
 File/Open…
ì Use the · tool to see the entire image and the ÿ tool to magnify
specific structures.
 To reverse magnification,
æ-click on the image or
double-click the ÿ tool in the
toolbar.
12. What structures help you determine which is the frontal view and
which is the lateral view?
13. Describe the articulating bone surfaces in the knee.
14. What structures hold the bones together?
ì Name the structures indicated by arrows. To check your answers,
press the > key.
ì Open Knee MRI. Use the > and < keys to move through the images in
the stack.
ì View this stack of images with false color tables (Fire-1 and Fire-2
work well).
 Options/Color Tablesã
15. How do false color tables help you to see structures in these MRI
images?
ì Close all images.
Hips in detail
ì Open Hip stack. These high resolution images are approximately
life-size.
ì Use the · tool to see the entire image and the ÿ tool to magnify
specific structures.
 File/Close… or click on the
˘ in the upper left corner
of the image.
See the Memory IPTechnique
Sheet if your buffer size is not
adequate to perform operations
on this image.
ì Try to name the connective tissue structures at the arrows. To check
your answers, press the > key.
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Articulations
105
ì Open Hip MRI and use the < and > keys to see the stack of images.
Apply a false color table if you want.
ì Close all open images.
Shoulders in detail
ì Open Shoulder stack. This image is a horizontal section through the
shoulder region.
 File/Open…
ì Use the · tool to see the entire image and the ÿ tool to magnify
specific structures.
ì Try to name the joint structures indicated by arrows. To check your
answers, press the > key.
ì Open Shoulder MRI and use the < and > keys to see the stack of
images. Apply a false color table if you want.
 Options/Color Tablesã
ì Close Shoulder MRI.
Keeping it together
Both the hip and shoulder joints are considered “ball and socket” joints. In
fact, the heads of the femur and the humerus are almost perfect spheres.
However, neither “ball” is entirely enclosed in its “socket”.
Determine what percent of the head of the humerus articulates with the
glenoid fossa of the scapula in this image.
1
ì With your eye, estimate the center of the humeral head.
3
ì Select the Ì tool and click sequentially on:
2
1) one edge of the glenoid fossa
2) the center of the humeral head
3) the other edge of the glenoid fossa
16. Record the angle diplayed in the Info window in Table 4.
17. The outline of the humeral head is a circle of 360°. What percent of the
of the head is in contact with the glenoid fossa in Shoulder Stack?
ì Close Shoulder Stack and open Hip Stack again.
ì Measure the angle represented by the contact between the head of the
femur and the acetabulum of the pelvic bone.
18. What percent of the head of the femur articulates with the acetabulum
of the pelvic bone in Hip Stack?
Hint:
Angle
360º
× 100 = χ %
19. Which joint do you think is more easily disarticulated, the hip or the
shoulder, and why?
20. What structures usually prevent these joints from becoming disarticulated, and how?
Range of motion and joint strength
Think about the shoulder, hip, and knee joints with regard to their range of
motion and strength. What is the relationship between joint motion and joint
strength?
21. Use your own body to compare the range of the motions allowed by
the shoulder, hip and knee joints. Rate each joint’s range of motion as
high, medium or low. Record your answers in Table 5.
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22. Use your own body to estimate the relative strength of the shoulder,
hip and knee joints as high, medium or low. Record your answers in
Table 5.
23. Describe the general relationship between joint range of motion and
joint strength.
More exploration
• Open one of the MRI stacks in this folder. The stacks show a series of
sagittal images of the knee, hip, and shoulder. NIH Image can reslice
these stacks in any other plane. Try reslicing a stack to explore different
structures of the joint from different planes of section.
ì Use the ‡ tool to make a straight line selection in a horizontal direction
across the stack.
ì Reslice the stack and enter .025 for the Slice Spacing. Click OK.
 File/Open…
 Stacks/Reslice
 Edit/Rotate Right or
Edit/Rotate Left
ì Rotate the slice if you want.
ì Try reslicing to obtain oblique sections.
• Open Hip radiograph. The bright object in this image is an artificial
(prosthetic) femoral head. What condition(s) could lead to the necessity
of replacing the femoral head with a prosthesis?
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Articulations
107
108
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Articulations
Name(s)
Class
Data
Sheet
Date
1. Using your observations of the animated joint motions, develop a unique definition for each joint movement. Record your answers in the table below.
Table 1
Joint motion
Definition of joint motion
Abduction
Adduction
Extension
Flexion
Circumduction
Rotation
Hypertension
Inversion
Eversion
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Articulations
109
Table 1 continued
Joint motion
Definition of joint motion
Dorsiflexion
Plantar flexion
Protraction
Retraction
Elevation
Depression
Pronation
Supination
Opposition
110
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2. What are the names of the articulating bones at each joint? Enter your answers in Table 2 below.
Table 2
#
Bone name
Bone name
Degree of
joint motion
Functional
classification
Structural
classification
1
2
3
4
5
6
7
8
9
10
11
3. Based on your own experience, and your textbook, are the numbered joints freely moveable, slightly
moveable, or not moveable? Enter your answers in Table 2.
4. Using the table in the margin of the lesson, enter the functional classification of the joints in Table 2.
5-7. Classify each of the numbered joints as fibrous, cartilaginous or synovial. Record your answers in Table
2.
8. Record your measurements in Table 3 below.
Table 3
Region of vertebral column
Thickness of intervertebral discs, mm
9. How do the intervertebral discs vary in thickness along the length of the spine?
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Articulations
111
10. Hypothesize a reason for the variations of intervertebral disc width.
11. Do you think the same variations would occur in four-legged land or marine mammals? Why or why
not?
12. What structures help you determine which is the frontal view and which is the lateral view?
13. Describe the articulating bone surfaces in the knee.
14. What structures hold the bones together?
15. How do false color tables help you to see structures in these MRI images?
16. Record the angle displayed in the Info window in Table 4 below.
Table 4
Joint
Angle of articulation
Percent contact
Shoulder
Hip
112
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17. The outline of the humeral head is a circle of 360°. What percent of the head is in contact with the
glenoid fossa in Shoulder stack? Record your answer in Table 4.
18. What percent of the head of the femur articulates with the acetabulum in of the pelvic bone in Hip
Stack? Record your answer in Table 4.
19. Which joint do you think is more easily disarticulated, and why?
20. What structures usually prevent these joints from becoming disarticulated, and how?
21. Use your own body to compare the range of the motions allowed by each joint. Rate each joint’s range of
motion as high, medium or low. Record your answers in Table 5 below.
Table 5
Joint
Relative range of motion
Relative strength
Shoulder
Hip
Knee
22. Use your own body to estimate the relative strength of each joint as high, medium or low. Record your
answers in Table 5.
23. Describe a general relationship between joint range of motion and joint strength.
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Articulations
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