GROSS THORAX MODULE - under construction (where have I seen that before!)

General Introduction

From actual bodies almost all the ideas of anatomical theory developed, but to understand this theory it is easier to use lists and labelled diagrammatic PowerPoint images, which present a simplified view and one that ignores anatomical variation from one person to another. The purpose of the anatomy lab is for you to find out what bodies are really like to the extent that we can do this once they are dead.
Another linking of knowledge and experience comes when you join your cadaver-based knowledge with live surface anatomy, surgical exposure, imaging techniques, etc, on patients.
This guide to your lab experience relates certain PowerPoints used in the lecture to labelled views of lab dissections. The images are separate from the brief linking and explanatory text and you'll reach them via links. In this way, you do not have one huge file to download, and you can leave or move in the program at any time. But, remember - you are in a website, so use BACK, not the exit X, which will whisk you right out of this module.

However, what we are showing you here are images to prepare you for what to experience and learn in the lab. You absolutely have to put on the gloves, feel, and explore, moving organs out of the way, putting them back, using your mind all the time and talking things through with your clasmates at the table. Ideas on the experience and the thinking are at this site . Cadaver
Read through it to prepare yourself.
In the lab, within your working group of three or four, someone needs to have brought a copy of Guy's Anatomy book, a list of the structures to be learned for the test, & whatever of this can usefully be printed out and brought. Although, the idea is to have most of this in your head when you come in. However, printing out the Figs in black and white of course loses the color used extensively to distinguish things. You can, later, go over the labels and leaders and restore them with colored highlighters.
For using this material at the computer, some may work from the screen just clicking the links, others may want a printed version to read along with going off for the images.

Gross dissection views

The gross dissection images on this site were photographed in 2003 & 2004 by Dr Barbara Kraszpulska with the technical help of Jeffrey Altemus, under the auspices of the Department of Neurobiology & Anatomy, West Virginia University. She holds the author's copyright.

Dissection views

(i) That you can see inside someone in this manner is only thanks to his/her generosity in allowing this use of his body after death. Respect the person's intent that you should be able to learn so as to be better at knowing and helping the living.

(ii) The appearance of the embalmed tissues and organs changes over time, so that in the lab you may meet darker shades of tan and brown.

(iii) In order to view the structures, usually several layers of connective tissue have had to be removed, so the images do not show how well and tightly our organs are packed in and fastened together.

(iv) One's first thought should be on orientation - How is the person lying? Face down/up/ or on side? What region am I looking at, and from what direction? Front back, left side, etc. [Know the technical names, supine, left lateral, etc.]

The first image of a series has a white stick figure to indicate orientation. [When you perform procedures on your patients, his/her orientation (position) wil also be important.] Thorax & Abdomen (anterior) - Orientation

(v) Later Figs then are labelled to show major structures, vascular and nervous structures, and other items of interest. .
Set in the text close to a dissection view may be a link to a relevant Powerpoint Fig from the Theory lectures.

(vi) At home, the images may take up to a minute to download, depending on your connection to the Web. They are in .jpg format which needs a viewer of some kind (Paint, Adobe, Camedia, etc.).
If you save the images all to one folder on your own computer, your viewer subsequently will give you a comprehensive showing of thumbnails or files that you can select from rapidly. Although, the links from the master text will not work, you can print that out and read along while looking at the images. Later, when I'm sure of how many .ppt and .jpg Figs I need to use, I may number them consecutively to connect them better with the text.

How we'll handle the list of structures to be known for the lab differs from the Bones list. At the end of this module will be the complete list for you to go through to see if you have a clear mental image of what each structure looks like in the lab and what its relations are. But before then the list will be broken up into the structures for particular thoracic regions, starting with Thoracic wall.

Parietal pleura versus visceral pleura
External intercostal mm. - - Internal intercostal mm. - - Transverse thoracic mm. - -
Neurovascular bundle - - Posterior intercostal artery and vein - - Intercostal nerve - -

diaphragm - - phrenic nerves -- inferior vena cava


Parietal pleura - - Visceral pleura - - Trachea - - Primary bronchi
Right lung
Superior, middle, and inferior lobes - - Horizontal and oblique fissures
Left lung
Superior and inferior lobes - - Oblique fissure - - Cardiac notch - - aortic-arch indentation

Introduction to the Thorax

The thorax is covered by skin and some fat. These will mostly have been dissected away leaving white fasciae (sheets of connective tissue), and brown muscles over and attached to the spine, bony rib-cage, scapula, clavicle, humerus and skull. There are substantial muscles for controlling the movements of the arms, and lying deeper are those smaller muscles on and between the ribs for enlarging the rib-cage at inspiration. (You've already seen dissection images of the back muscles in Guy's Computer Program when doing the Axial Skeleton)
This multilayering is characteristic of the body wall - chest and abdomen. Be aware (i) that layers may have been removed so that the now topmost layer lay deeper in life, and (ii) that its position may be included in the name of the muscle or fascia, but (iii) the muscle has a characteristic orientation which helps to identify it. The layering is very much in the surgeon's mind as she/he approaches deeper organs neeeding attention.
As we go through the thorax images, we shall be going from superficial to deep, until we have removed lungs and/or heart and are looking at the mediastinal structures.

Our first dissection image for learning will be of the ventral or anterior thorax, so first a schematic PowerPoint to show what major superficial muscle we can expect to see. . [The image may appear immediately, or you may have a menu to save or open from its present site. It will open quickly, and you already have the image from the 205 lecture ppts)] . Pectoralis major ppt Then the view of it as in the lab.

The next dissection image (DI) marks the general territories of thorax and abdomen, plus the Lft & Rt pectoralis muscles. Anatomy from now on will be much about territories and boundaries. Pectoralis major

Note in the dissection that we have to allow for a different orientation from that of the schematic, and that the origin and insertion are usually obscured. However, you'll recall that sometimes on prepared skeletons many bones are marked with the names of the muscles at the sites where they attach.
Next we are still on anterior chest wall, but a large piece has been sawn out, partly dissected (more so on the left side). But the orientation is new - we are viewing the wall from behind! . (as in . Anterior thoracic wall ppt) . Anterior thoracic wall 1

Here we have the same piece of front chest wall with major structures labelled . Anterior thoracic wall cntd

Next we are back to the intact cadaver for orientation . Pectoralis major
The same view now has the intercostal muscles labelled. (Compare . Intercostal MM ppt). However, the external intercostal MMs were too enthusiatically dissected - not much remains. In the lab, find a better specimen and insert finger or probe between the two muscle layers. (We'll save the transverse thoracic muscles for later when we return to the anterior chest wall for its vessels.) . Intercostal muscles
[Three minor caveats: (i) The adjective 'oblique' is not include in the standard terminology. I added it in order to emphasise the close relation of thoracic to abdominal-wall muscles; (ii) there is an additional, innermost muscle layer, with fibers behaving like the internal intercostal MMs, but set deeper, with the vessels and nerves sited between the layers; & (iii) the individual muscle layers do not extend completely from sternum to vertebrae, but vary in their coverage - although there is much of the rib cage where one finds all three, other more anterior or posterior sites have only two layers or sometimes one layer.

Note also the use of 'm, a, v', and 'n' for muscle, artery, vein, and nerve. Also, that, for many structures, one needs to indicate whether it is right or left.
There are more muscle & fascia layers on the BACK (dorsum) (to give thicker padding protection on our vulnerable dorsal side; and because the spine is there). The chest front is simpler, except that deep in the skin are the mammary glands. We'll leave the major muscles of the posterior thoracic wall for a separate module on the back, since 'the back' serves also the neck, head and pelvic region.

Still the same orientation to show that further dissection of the intercostal mm exposes the parietal pleura - the membrane lining the pleural (lung) cavities and covering the upper face of the diaphragm . Parietal pleura

Here the body has the same orientation, but the entire anterior chest wall has been sawn out leaving jagged cut ribs, and revealing the right lung, and sort of centrally the pericardial sac enclosing the heart. The diaphragm attaches to the chest wall so a cut edge of it is visible. . Lung & pericardial sac exposed

Note that the surface of the lung IS the visceral pleura, in distinction to the parietal pleura lining the pleural cavity and over the diaphragm. . Two pleuras & parietal pericardium . ( Lungs ppt)

Next, the orientation has changed to 7-to-1 o'clock, and the lungs have been taken out of both pleural cavities. The heart is still within its sac. Note how the diaphragm 'domes up' into the right (and left) pleural cavity . Pleural cavity

Note here the new orientation looking down at an angle on the diaphragm with the heart (removed) sitting left-of-center on it. See the dark congealed blood where the inferior vena cava comes up through the diaphragm (& inferior pericardium) to enter the right atrium . Diaphragm & IVC

At the back of the Rt pleural cavity the repeating striped pattern of ribs and intercostal structures can be seen . Intercostal structures 1

Looking deeper into the Rt posterior pleural cavity (with a small change in cadaver orientation) the specific structures in the intercostal spaces are clearly visible, although small . Intercostal structures ctd . and . ( Intercostal structures ppt)

Each intercostal space has three main structures - white and collapsible when felt (artery). white and solid (nerve), and dark and fragile (vein). At the vertebral body (hard), one can confirm which is artery (should continue over the body to the descending aorta) and which is nerve (should bury itself where rib meets vertebral body as the nerve goes on its way to the spinal cord).
?th IC nerve, etc is because, without counting, one cannot be sure which IC space is which.) . Intercostal A, V, & N

Finally for thoracic wall, in the same anterior location we see the rather insubstantial transverse thoracic muscles (better preserved on the Rt). [Note that 'thoracic' applies more to the anterior chest wall, and 'intercostal' more but not exclusively to the posterior wall.} . Transverse thoracic mm

Here we are back to the inside of the front chest wall to see a similar paralellel white dark pattern where the internal thoracic artery and vein run side-by-side and just lateral to the sternum . Internal thoracic A & V

Aside from the thoracic walls, the other important boundary for the thoracic cavities is the diaphragm. In the frontal dissection view, the heart has been lifted up off the diaphragm.., but the Fig gives an idea of its lateral extent and shape. [The probe is on the left phrenic neve controlling contraction of that half of the diaphragm ( Phrenic nerves ppt). . Diaphragm . [The diaphragm is quite thin (feel) and can be torn through, allowing sucked-up herniation of abdominal contents into the lungs' space. 1 in around 2200 children is born with congenital diaphragmattic hernia; and it is a not uncommon traumatic injury in dogs and cats.)
This view repeats an earlier one showing the Rt intercostal structures, but is used here to emphasize the visible right half of the diaphragm and the phrenic nerve serving it . Diaphragm 2

Here, on the other side of the mediastinum, are three nervous structures to be distinguished: (i) the phrenic nerve running directly to the diaphragm; (ii) the vagus nerve, stopping frequently to attach to and serve the aorta, esophagus, etc; (iii) at some distance dorsally, the sympathetic trunk/chain connecting ganglia alongside the vertebral bodies (the chain is not actually visible here) . . Vagus nerve
Note: (a) that these are all left structures, to be matched by right-side versions - search on both sides: (b) one only catches glimpses of the nervous system - nerves come from somewhere, and later will branch to serve other structures, e.g., some vagal nerve fibers are on their way to the upper abdomen

In the next dissection view, the anterior chest wall has gone, along with the Rt front parietal pleura, thus exposing the Rt lung in situ (in place). The lung's lobes and two fissures are visible. (In the lab, insert fingers into the fissures to feel their depth.) Note for when the lung is by itself, out of the chest that the base of the lung (inferior lobe) is indented by the upwardly protruding diaphragm. . Rt lung in situ . . Rt lung - lobes & fissures

Although rather dark, this image shows the territories of the isolated Rt lung, as seen from its medial (mediastinally-facing) side. In the lab, position the lung upright by finding the blunt apex (top) and the base, with its diaphragmattic depression - try pushing a fist up into it. . Rt lung's medial face

Still on the medial face, we concentrate on the structures at the hilum (hilus) or root of the lung, where the lung connects with mediastinal tubes, or identifying hilar structures it helps first to ID the apex of the lung, since the pulmonary artery/arteries (A/AAs) should lie superior to the pulmonary veins. However, critical to the correct IDs is the wall thickness: the bronchus/bronchi has a thick wall with palpable reinforcing cartilages. Having identified the bronchi, of the vessels, the veins should have significantly thinner walls than the A/AAs. [Why the singular/plural? Quite often the particular tube has divided before entering the lung, or splits as it does so (examine the AAs here); and anticipate variation] . Bronchus, & pulmonary A and VVs
Now try identifying structures of the left lung (( Left lung (medial) ppt), looking for the absence of a horizontal fissure, but the presence of an aortic-arch impression, a cardiac notch, and the adjacent little protruding lingula.

The same basis for identifying lung-root structures applies when one takes a lateral view of the mediastinum to see where the lung connects with its mediastinal counterparts. Note that next image, although of although of the right side of the mediastinum does not match the Rt lung just shown. . Lung connections - Rt side of mediastinum

This view has been rotated into a conventional head-up orientation. Just posterior and to the left of the SVC one can just make out the trachea branching into the Rt & Lft bronchi. All three have a 'ribby' feel (and look) from their reinforcing cartilages. Posterior to the trachea, the esophagus runs all the way through the thorax, to penetrate the diaphragm (exact point not in view). Just to the left of the esophagus and more lateral to the vertebral bodies descends the thoracic aorta. [find the azygous vein to the right of the vertebral bodies.] With the heart out, the parietal pericardium flops into abnormal shapes. Trachea, bronchi & esophagus in posterior mediastinum

Still to come are views of the thoracic duct

Thus far, our approach has been very fragmented, taking a few structures at a time to allow for steady, easy building of a body of knowledge. For a comprehensive review, we can take a look at some dissection videos made by Dr ?? of U Wisconsin medical School. These will ask you to download Quicktime as the player. The tone of the dissections is far too orange, and is actually the uncovering of dissections made earlier. However, the videos have some value, now that you know what to expect. They are at U Wisconsin Anatomy
Once there, double click the Gross Anatomy Icon (lower, left), and you'll see a menu of 27 dissections. Try # 4 Thorax (runs 26.5 mins, but can be stopped in Quicktime), and # 5 Posterior Thorax (21 mins)

NBAN 206 MODULE II Thorax, Cardiovascular System, Respiratory System, Lymphatics

Lab Assignments
Structures to be identified for Anatomy 206 taken from Guy Lessons 41,42,43,44 and Marieb text

Parietal pericardium - - Visceral pericardium
Vessels on the outside of the heart:-

  • Left coronary artery
  • Left anterior descending artery (LAD) / anterior interventricular
  • Right coronary artery
  • Coronary sinus
  • Great cardiac vein - -

    Great vessels entering and leaving the heart:-

  • Superior vena cava (SVC)
  • Inferior vena cava (IVC)
  • Pulmonary trunk
  • Pulmonary arteries
  • Pulmonary veins
  • Aorta

    Atria (right and left) - - Ventricles (right and left) - - Interventricular septum - - Atrio-ventricular valves Mitral, Tricuspid - - Chordae tendinae - - Papillary muscles - - Semilunar valves Aortic, Pulmonary

    - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
    Major arteries of Systemic Circulation (Marieb text p.344)

    Ascending aorta - - Coronary vessels of the heart - - Arch of aorta - - Brachiocephalic trunk - - Right common carotid a. (to head and neck) - - Right subclavian a.(to right upper limb) - - Left common carotid artery (to head and neck) - - Left subclavian artery(to left upper limb) - -

    Upper limb blood supply (same on both sides)
    Right or left subclavian aa. (same on both sides) - - Axillary aa. - - Brachial aa. - - Radial aa. and Ulnar a. - -

    Thoracic wall blood supply
    Descending thoracic aorta (only one of these) - - Intercostal aa. (same on both sides)

    Pelvis & Lower Limb Blood Supply (Same on both sides)
    Common iliac aa. - - Internal iliac aa. (to the pelvis) - - External iliac a. (main blood supply to the lower limb) - -Femoral aa.

    Major VEINS of systemic circulation (Marieb text, p.346)

    Superior vena cava (only one of these) collects venous blood from all veins above the diaphragm - -
    Tributaries to the superior vena cava(same on both sides)

  • Brachiocephalic vv. - -
  • Subclavian vv. - -
  • Internal jugular vv.

    Inferior vena cava (only one of these) collects all venous blood from veins below the diaphragm
    - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

    Paranasal sinuses:-
    Frontal - - Sphenoid - - Maxillary - - Ethmoidal
    Nasal conchae
    Superior - - Middle - - Inferior
    Auditory tube - - Palate:- Hard palate - - Soft palate - - Uvula - -
    Tonsils:- Pharyngeal - - Palatine - - Lingual - -
    Larynx - - Epiglottis - - Thyroid cartilage - - Cricoid cartilage
    Vocal folds:- False - - True
    Trachea - - Primary bronchi
    Right lung - - Superior, middle, and inferior lobes - - Horizontal and oblique fissures
    Left lung - - Superior and inferior lobes - - Oblique fissure - - Cardiac notch - - Parietal pleura - - Visceral pleura

    External intercostal mm. - - Internal intercostal mm. - - Transverse thoracic mm. - -

    Neurovascular bundle - - Posterior intercostal artery and vein - - Intercostal nerve - -

    diaphragm - - phrenic nerves

    Trachea - - Esophagus - - Vagus nerves (left) - - Azygos vein - - Thoracic duct (maybe) - - Phrenic nerves (left) - - Sympathetic trunk