Body Plan & Introduction to the VH Dissector

Begin with a posterior view of the donor body. 

Remove the skin to visualize the structures underneath. In the lab, you will see subcutaneous fat and fascia (connective tissue coverings), but the VH dissector takes us directly to the muscular layer.

Turn the body to see an anterior view.

Turn it again to see a left lateral view.

We will now explore the cross-sectional views of the VH dissector. There are three boxes in the cross-section panel. The top is a transverse plane, the middle is a sagittal plane, and the bottom is a coronal plane. The transverse plane is especially useful because many CT scans show this view. 

Highlight the Latissimus dorsi muscle and observe that the highlight shows in both the main dissection panel and in the transverse section. Try moving the cross-sections around to see if you can find this muscle in the coronal and sagittal sections!

Here is an example of how to show this structure in all three cross-sections. Notice that moving one cross section affects the others. The lines in each cross-seciton panel can help you orient yourself to the other planes of section.

Now that you have familiarized yourself with the planes of section, focus on the diaphragm which separates the thoracic cavity from the abdominal cavity. Recall that it is formed from contributions from the following mesoderm sources:

• Septum transversum (ST-purple) - the part ventral to the gut tube

• Visceral mesoderm around the gut tube (pink) - the medial aspects close to the esophageal opening

• Pleuroperitoneal membrane (PPM-orange): part that fills in the pericardioperitoneal canals

• Parietal mesoderm of body wall (red): forms perimeter of the diaphragm.

bw = body wall

Examine the diaphragm in each of the cross-sectional planes. Grab the sagittal cross-section and watch the coronal cross-section follow as you move the sagittal image up and down. Also observe the transverse cross-section when you release the mouse. Now move the coronal cross-section from side to side as you observe the axial cross-section follow. Also observe the sagittal cross-section when you release the mouse. Do this until you get the sense that the diaphragm is a domed structure with two peaks. 

Visualize the structures that pass between the thorax and abdomen. 

• Aorta: most posterior and inferior

• Esophagus

• Superior vena Cava: most superior and anterior

This is a prosection showing contents of the dorsal body cavity including the cranial cavity and vertebral canal.   

Start with a posterior view of the VH Dissector body.

Highlight the extrinsic (superficial and intermediate) muscles of the back.  

Remove the extrinsic muscles to reveal the deep (intrinsic) muscles of the back

Highlight the intrinsic muscles of the back

Remove the muscles of the back to reveal the vertebrae, ribs and segmental spinal nerves

Add in vascular structures and highlight the intercostal neurovascular bundles

In the reconstructed VH dissector body it is not possible to see the layers of skin and fascia, but it is well visualized in the sectional anatomy.  One place where the division between superficial and deep fascia can be appreciated is in the thigh.  

Here the transverse and coronal planes have been overlaid on the 3D reconstruction.

Zoom in on the sectional views.  Note that two structures have been highlighted.  The iliotibial tract (deep fascia of the thigh) in purple and the tensor fascia lata muscle (a muscle that pulls on the iliotibial tract) in pink.

Use the middle pane (sagittal section) to move the coronal plane anterior and posterior, and the transverse plane superior and inferior. This will help you appreciate how the deep fascia envelops the muscles of the thigh, and is especially thick laterally. 

The skin and the superficial fascia (hypodermis) can be seen superficial to the deep fascia.