Anamtomy And physiclogy Labs 1,3,and 4

EXPERIMENT 4: PHYSICAL SKELETON - THE AXIAL SKELETON As you have learned, the bones of the body are separated into the axial and appendicular skeleton based on their location. The axial skeleton is divided into three regions: the skull, the vertebral column, and the thoracic cage. In this exercise, you will observe the bones that comprise these three regions along with their functionality using the virtual model and the skeleton images.

PROCEDURE

The Skull 1. The skull is divided into two groups of bones: cranial bones and facial bones. Begin by locating the cranial bones on the

virtual model. The cranium is composed of eight bones: the frontal bone, two parietal bones, two temporal bones, the occipital bone, the sphenoid bone, and the ethmoid bone. Use Figures 10 and 11 as guides.

2. Stand in front of a mirror and palpate the cranial bones on your own skull. Note that you may not be able to palpate all the bones. Use Figures 10 and 11 and Table 2 (Introduction) as a guide.

Experiment 4Physical Skeleton - The Axial Skeleton Materials Virtual Model

*Mirror

Experiment Inventory

Figure 10: Cranial bones.

Note: You must provide the materials listed in *red.

3. Next, try to locate the specified cranial bone markings listed in Table 3 (Introduction).

4. Locate the facial bones on the virtual model. There are 14 facial bones: the mandible, two maxillae, two palatine bones, two zygomatic bones, two lacrimal bones, two nasal bones, two inferior nasal conchae, and the vomer. Use Figures 10 and 11 and Table 4 (Introduction) as guides.

5. Stand in front of a mirror and palpate the facial bones on your own skull. Note that you may not be able to palpate all the bones. Use Figures 10 and 11 and Table 4 (Introduction) as guides.

6. Next, try to locate the specified facial bone markings. Use Table 4 (Introduction) as a guide.

7. The hyoid bone is a U-shaped bone located above the larynx. It facilitates swallowing and tongue movement. The hyoid bone is uniquely articulated via muscles and ligaments. Figure 12 provides a visual reference as to where the bone is located in the human body.

The Vertebral Column 1. Begin by locating the vertebral column on the virtual model.

2. Locate the three regions of the vertebral column (Figure 13, next page).

• Cervical vertebrae – The superior portion of the vertebral column. It forms the neck region and is composed of seven vertebrae (C1 – C7).

• Thoracic vertebrae – The twelve vertebrae (T1 – T12) located in the thorax that articulate with the ribs.

• Lumbar vertebrae – The five vertebrae (L1 – L5) that are located in the lower back.

3. Continuing down the vertebral column, locate the sacrum and the coccyx. The sacrum lies inferior to the fifth lumbar vertebrae, and is composed of five fused vertebrae. Inferior to the sacrum lies the coccyx. The coccyx is smaller and composed of four fused vertebrae.

4. Next, observe the curvature of the spine. Notice the primary curvature of the thoracic and sacral regions, (concave, anterior facing) and the secondary curvature of the cervical and lumbar regions (concave, posteriorly facing).

5. Locate the individual vertebra. Observe the common features noted in Table 7.

6. Notice the intervertebral discs between the bodies of neighboring vertebrae. This fibrocartilage cushion is located between all vertebrae except C1 and C2.

7. Looking closer at the cervical region, note that the C1 vertebra, called the atlas, does not contain a vertebral body. Instead, the superior surface of this vertebra contains deep indents that articulate with the occipital condyles at the base of the skull. This articulation, called the atlantooccipital joint, allows a person to nod their head up and down.

Figure 11: Cranial bones.

Figure 12: The hyoid bones.

8. Inferior to the atlas is the C2 vertebra, called the axis. This vertebra contains a large superior projection called the dens that articulates with the atlas to rotate the head side to side.

9. The remaining cervical vertebrae possess a few unique characteristics. Examine the specified features of the cervical region, and record your observations in Table 12 at the end of this experiment.

10. The spinous process of the C7 vertebra is also called the vertebra prominens because of its size and location. Palpate your vertebra prominens. To do this, place your hands on the superior midline of your neck, and slowly begin moving inferiorly. The first prominent bony projection is the vertebra prominens.

11. Using the virtual model, locate the 12 thoracic vertebrae. Remember, these vertebrae can be easily spotted because of their articulation with the ribs.

12. Examine the specified features of the thoracic region, and record your observations in Table 13 at the end of this lab.

13. When looking at the articulation between the thoracic vertebrae and the ribs, notice the inferior and superior costal facets (flat surfaces) off the vertebral body.

14. Moving inferior, locate the five vertebrae of the lumbar region. Examine the specified features, and record your observations in Table 14 at the end of this lab.

15. Inferior to the L5 vertebra lies the sacrum. Use Table 11 to locate the specified features of the sacrum on your skeleton. Use Figure 14 as a guide.

16. You may attempt to palpate the median sacral crest of your own sacrum. However, this should be done only in private due to the location of the sacrum.

17. Continuing inferior, locate the coccyx. As noted earlier, the coccyx is formed through the fusion of 3 – 5 (though most often four) vertebrae. This is the tailbone of the human body and represents a vestige of a tail that develops during the early embryonic stages but disappears before birth.

Vertebral Feature Location

Vertebral Body Central, anterior portion used in transmitting weight throughout the body. Vertebral Arch Composed of pedicles and laminae that extend posteriorly from the vertebral body.

Vertebral Foramen Opening formed by the vertebral body and vertebral arch through which the spinal cord passes. Transverse Processes Lateral projections off each side of the vertebral arch.

Spinous Process Posterior projection off the medial portion of the vertebral arch.

Inferior and Superior Articular Processes

Lateral paired projections off the vertebral foramen used in articulation with neigh- boring vertebrae. Inferior articular processes project inferiorly from the pedicle,

whereas the superior articular processes project superiorly to the pedicle.

Intervertebral Foramina Openings between vertebrae that allow the spinal nerves to enter.

Figure 13: The vertebral column.

Table 7: Vertebral Feature Location

Table 8: Sacral Feature Locations

Sacral Feature Location

Median Sacral Crest Bony projections located on the midline of the dorsal surface; composed of the spinous processes of the fused vertebrae.

Alae Bony projections formed from the fusion of the transverse processes of the fused vertebrae located on the lateral edges; articulate laterally with the hip bone and assist in weight distribution.

Sacral Foramina Small openings located ventrally and dorsally that transport nerves and blood vessels.

Sacral Canal Continuation of the vertebral canal; ends at the sacral hiatus (a large opening near the coccyx).

Sacral Promontory Bony protrusion on the anterior body of the sacrum used as a marker for ob-stetric measurements.

The Thoracic Cage 1. The thoracic cage is composed of the sternum and 12 pairs of ribs. This structure protects the organs within the thoracic

cavity, including the lungs and heart.

2. Locate the sternum. The sternum is a flat bone located on the anterior surface of the thoracic cage. It is composed of three bones that have fused together: the manubrium, the body, and the xiphoid process. Use Table 9 to locate the three sections of the sternum on the virtual model. Refer to Figure 15 as a guide.

3. There are several features unique to the sternum. Locate the specified features of the sternum using Table 9.

4. Palpate the jugular notch and sternal angle on your own body. You will not be able to palpate the xiphisternal joint.

5. Locate the 12 pairs of ribs on your skeleton. Notice the articulation between the head, the tubercle of the ribs, and the thoracic vertebrae. Also, note the downward curve of the ribs as they move toward the anterior surface.

6. Use Table 15 at the end of this experiment to examine the specified features of the ribs, and record your observations.

7. The ribs are broken down into three categories based on their attachment to the sternum: true, false, or floating. Use Table 10 to locate the three rib types.

8. Focus on rib 4 (a typical rib). Use Table 11 to locate the important features on this rib.

9. Notice the space between each rib. This space is called the intercostal space and contains three layers of muscle. These muscles play a key role in respiration.

Figure 14: The vertebral column.

Figure 15: The thoracic cage.

Table 9: Sternum Feature Locations

Sternum Feature Location

Manubrium Superior section of the sternum; articulates with the clavicle and first pair of ribs.

Body Longest section of the sternum; articulates with the second through seventh pairs of ribs.

Xiphoid Process Inferior section of the sternum; composed of hyaline cartilage in children, but ossi-fies into adulthood.

Jugular Notch Superior concave margin of the manubrium.

Sternal Angle Articulation between the manubrium and the body; comes together at a slight an- gle, forming a crest that allows anterior movement during inhalation; also, acts as a landmark.

Xiphisternal Joint Articulation between the body and the xiphoid process.

Table 10: Rib Feature Specifications

Ribs Specifications

True Ribs Ribs 1 – 7. These ribs are called true ribs because of their direct attachment to the ster-num via their costal cartilage.

False Ribs

Ribs 8 – 10, also called the vertebrochondral ribs, are called false ribs because the car- tilage of these three ribs connects together and then indirectly attaches to the sternum via the cartilage of rib 7. Ribs 11 – 12 are also called false ribs, although they do not attach to the sternum. See more below.

Floating Ribs Ribs 11 and 12, also called the vertebral ribs, are called floating ribs because they do not connect to the sternum at all.

Rib Feature Locations Vertebral End Articulates with the vertebral column.

Sternal End Articulates with the sternum (directly or indirectly) or does not articulate at all (ribs 11 and 12).

Head Located on the vertebral end of the rib; articulates with the corresponding tho-racic vertebrae as well as superior vertebrae and the intervertebral disc typically.

Tubercle Located on the vertebral end of the rib; articulates with the transverse process of the corresponding thoracic vertebrae. Neck Area between the head and tubercle. Body Primary portion of the rib.

Table 11: Rib Feature Locations

Vertebral Feature Observations

Size of cervical vertebrae in compari- son to those of the thoracic and lumbar

region

Shape of the vertebral foramen

Spinous process of the C3 – C6 vertebrae

Spinous process of the C7 vertebra

Data Sheet Experiment 4 Data Sheet Table 12: Cervical Vertebrae Observations

Table 13: Thoracic Vertebrae Observations

Table 14: Lumbar Vertebrae Observations

Table 15: Rib Feature Observations

Vertebral Feature Observations Size and weight of the thoracic vertebrae

in comparison to those of the cervical and lumbar region

Shape of the vertebral body

Appearance and projection direction of the spinous process

Vertebral Feature Observations Size of the lumbar vertebrae in com- parison to those of the cervical and

thoracic region Shape of the vertebral body

Appearance and projection direction of the spinous process

Rib Feature Observations Length of ribs 1 – 7 (do they increase or

decrease in length?) Length of ribs 8 – 12 (do they increase or

decrease in length?) Articulation of the ribs and thoracic ver- tebrae (notice the specific rib and verte-

bra that articulate)