Biology, Skeletal System

Learning the bones of the Skeletal System

Microscopic structures

1. Osteon

2. Osteocyte

3. Central canal

4. Canaliculi

5. Chondrocytes

Skeletal structures

1. Epiphysis

2. Diaphysis

3. Periosteum

4. Articular cartilage

5. Medullary cavity

6. Yellow marrow

7. Spongy bone

8. Compact bone

Bones to learn and know for lab quiz:

Axial skeleton

Frontal, parietal, occipital, temporal, sphenoid, ethmoid, mandible, maxillae, palatine, zygomatic, nasal, vomer, lacrimal, cervical, thoracic & lumbar vertebrae, sacrum, coccyx, ribs & sternum

Appendicular skeleton

Clavicle, scapula, humerus, radius, ulna, carpals, metacarpals, phalanges, coxal, femur, patella, tibia, fibula, tarsals, metatarsals, phalanges.

Escience – Post lab questions to answer for virtual model study in experiments 6 and 8

Axial Skeleton


Appendicular Skeleton


Experiment 9: Articulations


Articulations, or joints, are formed when two bones come together. The joints of the body are crucial in keeping the body intact and in providing movement. Joints can be classified two ways: structure or mobility. As mentioned earlier, the three types of structural classifications are fibrous, cartilaginous and synovial joints. The three types of mobility based classifications are synarthroses (immobile), amphiarthroses (slightly mobile) and diarthroses (mobile). Though both classifications are useful, we will focus on the structural classifications. In this exercise we will examine the different types of articulations.

MaterialsSkeleton Model


Fibrous Joints

1. Fibrous joints are held together with fibrous tissue and do not posses a joint cavity. Though there are a few fibrous joints that are amphiarthrotic, most are synarthrotic. There are two main types of fibrous joints: sutures and syndesmoses.

2. Sutures are composed of tight fitting bones with little or no connective tissue and are only found within the skull.

3. In syndesmoses, the bones are joined together by a small amount of dense fibrous connective tissue. Though there can be slight movement within the joints, they’re typically considered synarthrotic.

4. Use Table 31 to locate the four prominent sutures between the cranial bones of the skull on the model skeleton.

5. Locate the articulation between the distal ends of the tibia and fibula on the model skeleton. Also, look at the articulation between the radius and ulna. These are both examples of syndesmoses.

Cartilaginous Joints

6. Bones are connected with either a plate of hyaline cartilage or a disc of fibrocartilage in cartilaginous joints. These joints, similar to the fibrous joints, do not have a joint cavity; although, most of them are amphiarthrotic.

7. There are two types of cartilaginous joints: symphysis and synchondroses. In symphysis joints, the bones are connected with disc of fibrocartilage. In synchondroses bones, the bones are connected with a plate of hyaline cartilage.

Table 31: Skull Suture Locations
Skull SuturesLocation
Coronal SutureArticulation between the posterior portion of the frontal bone and anterior portion of the parietal bones.
Lambdoid SutureArticulation between the anterior portion of the occipital bone and the posterior portion of the two parietal bones.
Sagittal SutureArticulation between the two parietal bones.
Squamous SuturesArticulation between the inferior portion of the parietal bone and the superior portion of the temporal bone.

8. Locate the pubic symphysis on the model skeleton. As the name suggests, this joint is a symphysis. Examine the vertebral column. Each vertebrae is connected via an intervertebral disc composed of fibrocartilage.

9. Locate the articulation between the first rib and the sternum on the model skeleton. This is an example of a synchondroses.

Synovial Joints

10. Synovial joints are the most common articulation within the body. Between the two articulating bones lies a joint cavity filled with synovial fluid allowing all synovial joints to be diarthrotic, though the type of mobility (side to side, multiple directions, etc.) varies.

11. Six subcategories have been created based on the type of movement because of the many synovial joints within the body. Use Table 32 to locate examples of the six different subcategories of synovial joints on the model skeleton. Become familiar with the movement associated with each example.

12. Using Table 33, perform the listed movements on the model skeleton. Then perform these same movements on your own body. Pay attention to the type of synovial joint (gliding, hinge, etc.) that is involved with each movement.

Table 32: Synovial Joint Information
Subcategory of Synovial JointsMovementExamples
GlidingFlat articulating surfaces allow for sliding movement side-to-side and back-andforth.· Intercarpal Joints at the wrist· Intertarsal Joints in the foot· Sacroiliac Joints
HingeArticulating surfaces between a convex bone and concave bone allow for uniaxial movement (one plane). Typically this movement is flexion or extension.· Elbow Joint· Knee Joint· Ankle Joint
PivotUniaxial rotation (one plane) occurs from the conical surface of one bone articulating with a shallow depression of another bone.· Atlantoaxial Joint (atlas and axis)· Radioulnar Joint
Condyloid (Ellipsoidal)An oval condyle of one bone fits with an elliptical cavity of another allowing biaxial movement (two plane).· Radiocarpal Joint (wrist)· Metacarpophalangeal Joints
SaddleBoth bones involved in the articulation possess both a concave and convex suface, called a saddle, that allows for biaxial movement (two plane).· Metacarpal of the thumb and the Trapezium of the wrist
Ball and SocketBall-like head articulates with a cup-like depression allowing for multiaxial movement (all directions).· Shoulder Joint· Hip Joint
Table 33: Types of Joint Movement
Type of MovementDefinitionExample
FlexionBending motion that decreases the angle between the two bones.In anatomical position, bring the palm of the hand towards the shoulder, bending the elbow.
ExtensionStraightening motion that increases the angle between the two bones (opposite of flexion).With the elbow bent and the palm of the hand touching the shoulder, straighten the arm, bringing the palm down to the original starting position.
AbductionMoving a body part away from the midline of the body.Move the left thigh laterally away from the midline of the body.
AdductionMoving a body part towards the midline of the body (opposite of abduction).With the thigh positioned laterally away from the body, bring it back towards the midline until it reaches the original starting position.
CircumductionMovement combining flexion, extension, abduction and adduction.In anatomical position, bend the wrist anatomically to produce flexion, then move the wrist laterally to produce abduction, then move the wrist posteriorly to produce extension and then move your wrist medially to produce adduction. Continue these motions, increasing the speed to produce a single motion.
RotationMovement around the longitudinal axis of the bone.With the head beginning in anatomical position, look left and then look right as if shaking your head “no”.
PronationRotating movement of the palm and forearm from an anterior position to a posterior position.In anatomical position with the palm facing up, rotate the palm medially until it is facing down.
SupinationRotating movement of the palm and forearm from a posterior position to an anterior position.With the palm facing down (posterior), rotate the palm laterally until it is facing up.
InversionMoving sole of foot medially.In anatomical position, move the sole of the foot medially.
EversionMoving sole of foot laterally (opposite of inversion).In anatomical position, move the sole of the laterally.
DorsiflexionBending movement of the ankle where the foot is flexed upward.In anatomical position, lift the toes upward as if standing on the heels.
Plantar flexionBending movement of the ankle where the foot is flexed downward.In anatomical position, point the toes towards the ground, as if standing on the toes.

Post-Lab Questions

1. What two ways can joints be classified? What are the three classifications of each type?

2. Fibrous joints are either sutures or syndesmoses. What is the difference between the two? Give examples of each type.

3. A symphysis and synchondroses are two classifications of what type of joint? What are the differences between the two classifications?

4. What allows synovial joints to be diarthrotic?

5. For the following, match the correct synovial joint to the movement it produces.

a. Pivot Joint 1. Uniaxial movement, typically flexion or extension
b. Gliding Joint 2. Uniaxial rotation
c. Ball and Socket Joint 3. Side-to-side and back-and-forth movement
d. Condyloid Joint4. Multiaxial movement
e. Saddle Joint5. Concave and convex surfaces of both bones allow for biaxial movement
f. Hinge Joint6. Ellipsoidal fit allows for biaxial movement

6. Fill in the chart below:

BoneArticulating BonesType of Synovial JointMovement

Experiment 11: Skeletal System of the Fetal Pig


In this exercise you will become familiar with the skeletal system of the fetal pig. Because the fetal pig had not reached its full gestation, many of the bones have not fully developed, but are instead still cartilaginous. Still, we can look at this structures to gain a better understanding of the axial and appendicular skeletons, along with the joints.

MaterialsFetal Pig Dissection TrayDissection Tools Kit String (should still be tied onto pig’s hooves)


1. To begin, lay your underpad down and place your dissecting tray on top of it. Lay out your dissecting tools. Be sure you have all of your safety equipment on before beginning the experiment.

2. Once prepared, gently open the bag your pig is in. Note: DO NOT destroy this bag or empty out the preserving solution within the bag, you will need it for the whole semester.

3. Lay your pig into the dissecting tray, dorsal side facing up. Slide the strings over the dissection tray to hold the pig in place.

4. Look at Figure 21 displaying the skeletal system of a grown pig. Notice the similarities and differences between that of your human skeleton and that of the pig.

Figure 21: The pig skeleton

5. Due to the rigidity of your pig, it typically will not stay in this position on its own so you will need to hold it while you examine the skeletal system.

6. Begin by examining, through the skin, the axial skeleton as shown in Figure 21. Feel the bones of the skull, then continue down the vertebral column feeling the vertebrae along the way. Notice that the tail of the pig is composed of caudal vertebrae. Note your observations in Table 34.

7. Slide the strings off of the dissection tray and gently turn your pig ventral side up. Slide the strings back under the dissection tray after the pig is correctly positioned.

8. Feel the thoracic cage of the pig. Though you will not cut into the pig today, feel the similarities that occur between the fetal pig and the human skeleton model. Note your observations in Table 34.

9. Turn your attention to the appendicular skeleton. The pig’s four appendages correlate to the human arms and legs. Use Figure 21 as a guide to try and feel the different bones of the arms and legs (humerus, femur, tibia, etc.). Note your observations in Table 34.

10. In Figure 21, look at the pelvic girdle of the pig. This structure appears noticeably different than that of a human. However, the innominate bones of the pig are created by the ilium, ischium and pubis.

11. Focus your attention on the joints of the pig. The pig should be fairly rigid due to the preservation fluids. However, you should still attempt to produce the movements created by synovial joints on the pig (e.g., flexion, rotation, etc.). Notice the joints at which these movements are possible. Do they correlate to human movement? Note your observations in Table 34.

12. You are now finished with the external observations of the skeletal system. Remember that as you dissect into your pig, you will be able to touch and feel the bones of the skeletal system. As the dissection progresses, always take note of the bones present within the fetal pig.

13. To finish, locate the bag the pig came in. Gently place the pig back into the bag and tightly secure the bag with a rubber band, or place in the zip-seal bag provided in the dissection box.

14. Place the pig back into the cool environment you had previously stored it in. Remember, the best place to keep the pig is in a cool, dark place.

15. After your pig has been put away, clean off your dissecting tray and dissection tools with soap and water. There should not be any biological scraps because you did not cut into the pig. However, biological scraps should not be thrown into the garbage.

16. Clean the area in which you worked with soap and water as well. As long as the underpad has not been damaged, keep it for future experiments.

Figure 22: Palpate the skeleton of the fetal pig using gloved hands.
Table 34: Skeletal Region Observations
Skeletal RegionObservations
Axial Skeleton 
Appendicular Skeleton 

Post-Lab Questions


1. What are some of the similarities and differences you noticed between the human skeletal system and the palpation of the fetal pig skeletal system?


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