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ANAT3007/3907 - Applied Anatomy – Thorax Year 2019

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APPLIED ANATOMY 1 – THORAX Year 2019 This part of the course aims to enhance your knowledge of anatomical relationships & cross sectional anatomy. It also aims to provide a different perspective of anatomy to the topographic one learnt from prosections in the practical classes.

The CT scans viewed in class cannot currently be made available on Canvas or photographed for reasons of copyright. However the Online reference below shows very similar labeled CT scans of normal anatomy that can be used for revision. Selected images from the CT scans in these sessions & also selected images from the websites are potentially examinable (see below). Examinable images from these sessions will be reviewed at the end of the course. ASSESSMENT PHOTOGRAPHS OF A FEW SELECTED IMAGES OF CT SCANS OF THORAX & UPPER & LOWER ABDOMEN MAY BE EXAMINED IN THE SPOT TEST. FEATURES WHICH YOU MAY BE ASKED TO IDENTIFY WILL BE RECOGNIZABLE IN JUST A SINGLE IMAGE WITHOUT THE NEED FOR SCROLLING. THE EXAMINABLE IMAGES FROM THESE SERIES WILL BE REVIEWED & DISCUSSED IN THE FINAL APPLIED ANATOMY REVISION SESSION, ALONG WITH SOME SAMPLE QUESTIONS.

N.B. ALWAYS CHECK LEFT & RIGHT ON CT SCANS

REFERENCES 1. INTERNET GOOGLE :THORAX/ANATOMY/PELVIS CT SCANS NORMAL ANATOMY Atlas of CT Anatomy of the Chest - W-Radiology w-radiology.com/chest_ct.php Mar 20, 2014 - Image 1. CT Anatomy of the chest, axial reconstruction. 1, Coracoid Process (scapula). 2, Clavicle (right side). 3, Right common carotid artery.

2. ROHEN IMAGE 8th ED, 261 (7th Ed p.255) - view features of the SVC & brachiocephalic veins prior to attending the Applied Anatomy class (see p. 2 of these notes under heading IMAGE 14) It is also suggested that you read the questions in the notes & where possible answer these prior to viewing the CT scans (some of the questions relate to what is seen in the scans & will have to be answered during the tutorial).

ANAT3007/3907 - Applied Anatomy – Thorax Year 2019

2 CT SCANS Conventional X rays are made by passing a beam of X rays from the X ray machine through the body part of interest & onto a recording device. This means that every structure on the path of the X rays will appear superimposed in the final image. The recording device may be a photographic film or the image may be recorded digitally. Digital images are becoming increasingly popular but some radiographers still use photographic film. This consists of a large format sheet of flexible plastic (polyester, nitrocellulose or cellulose acetate) covered with photographic emulsion. The photographic emulsion consists of gelatin with suspended crystals of silver halide (mostly silver bromide with a variable amount of AgI & AgCl). The silver halide crystals undergo changes when exposed to light, electrons or X rays. These are developed & fixed so they are permanent. In the case of X rays & CT scans the images, whether film or digital, are presented as photographic negatives i.e with the most exposed parts of the emulsion being the blackest (these represent the parts of the body that transmit X rays most readily). CT scans are also made using X rays. Unlike conventional X rays images which show all structures in the path of the beam of X rays, the CT images consist of a series of slices usually 5mm apart. The patient lies on a table and passes through the centre of the X ray scanner tube. A thin beam of x-ray passes through patient to the detector. This results in a series of image slices. This means that the images are essentially two dimensional rather like a series of histological sections. These are shown a series of small images on a photographic film or a series of images on a disc. The advantage of the latter is that they can be scanned sequentially by using the scroll device on the mouse which allows features to be traced from one image to the next for identification. It is also possible for slices closer together than 5mm to be taken. 3D reconstructions can be made from these 2D images. Contrast medium may be administered prior to carrying out the CT scan. This may be given intraveneously, orally or rectally. Most contrast media are barium or iodine based compounds. The aim of these is to improve visualization of blood vessels or hollow organs.

ANAT3007/3907 - Applied Anatomy – Thorax Year 2019

3 2/2/06 Female 37 years CT Chest & Upper Abdomen + CONTRAST (in IVC) (RECON 2, POST CONTR 2TH ON CT scan LIST, 353 imges) SERIES 3 – AXIAL (HORIZONTAL) (Recon 2: POST CONTRAST) IMAGE 1 - trachea with air filled lumen, posterior indentation is oesophagus. - body first thoracic vertebra (T1). IMAGES 2 - 4 - rib 1 appears initially as articulation with transverse process of T1 (IMAGE 2) (ribs are higher posteriorly) then with body of T1 (IMAGE 4). Rib 1 can be traced along its length to its anterior articulation in IMAGE 10. Then scroll back to IMAGE 4 to see: - rib 2 just posterior to rib 1 (faint) - dark shadow superimposed on left rib 1 is thoracic cavity.

QUESTION 1 Is the articulation in IMAGE 4 the only costocorporeal joint for this rib?

yes QUESTION 2 Name the bone that rib 1 articulates with

QUESTION 3 Name the precise location of the anterior articulation of cartilage rib 2 (relate to surface landmarks)

QUESTION 4 (do this after consulting references) The structure with which rib 2 articulates is an important surface landmark which approximately overlies a number of internal structures or junctions. Name as many of these structures & junctions as possible. (see Course Book W1, p.22)

IMAGE 7 - thoracic cavity - the presence of lung can be deduced by the light speckles (bronchi or blood vessels). You may need to adjust contrast & brightness to see these. - articulation of rib 2 with transverse process & body of T2.

ANAT3007/3907 - Applied Anatomy – Thorax Year 2019

4 QUESTION 5 Are there any other articulations for the head of rib 2?

IMAGE 11 - articulation of rib 3 with body & transverse process of vertebra

IMAGE 14 The next part of the observations involves looking at the cross sectional relationship of the great vessels in the neck using contrast medium in the SVC as a guide. The contrast medium will pass a short distance into at least some of its tributaries of the SVC facilitating identification of the tributaries & visualization of some of their relationships. Preliminary reading Rohen, 8th Ed, p.279 (7th Ed p.255). The Rohen image shows both brachiocephalic veins. The left brachiocephalic vein is almost horizontal & is thus at the same cross sectional level as the top of the superior vena cava (SVC). The right brachiocephalic vein is more vertically oriented & is thus above the SVC.

IMAGE 14 Note position of Left & Right on the image Use diagram to identify SVC & LEFT brachicephalic vein & related structures

Dark air filled structures: Trachea (larger & anterior) & oesophagus (posterior) Structures adjacent & anterior to the trachea from right to left (clockwise direction) - SVC – identify by white contrast medium - brachiocephalic trunk - (small) left common carotid (posterior to left brachiocephalic vein) - left subclavian artery (same level as oesophagus) (Confirm identification of these arteries by seeing them branching from the arch of the aorta in IMAGE 16)

ANAT3007/3907 - Applied Anatomy – Thorax Year 2019

5 IMAGE 15 - articulation of rib 3 with body & transverse process of vertebra 3.

IMAGE 16 - internal thoracic artery (smaller, whiter, lateral) & vein , trachea, oesophagus, arch of aorta.

QUESTION 6 Identify the location of the internal thoracic artery & vein using anatomical landmarks. (see W3, Course Book, p.63, 65)

QUESTION 7 Where do the internal thoracic artery & vein arise & where do they terminate?

IMAGE 17 - look anterolateral to spinous process for zygaphophyseal joints (between vertebral articular processes) - note direction of articular facets.. - arch of aorta is elongated pale gray structure just to left of SVC (with contrast medium), trachea & oesophagus (black due to contained air). - bronchi (view right lung) - note cartilage

IMAGE 18 - arch of the azygos (curved, faint & just to right of the trachea) can be seen emptying into SVC (striated appearance is due to contrast medium leaking from the SVC). You may need to move forward to IMAGE 26 where azygos is clearly seen in cross section in right posterior mediastinum just behind oesophagus - then scroll back.

IMAGE 19 - ascending & descending aorta. - hilar regions of lungs - trachea - bronchi + cartilage (view both lungs)

ANAT3007/3907 - Applied Anatomy – Thorax Year 2019

6 IMAGE 21 - Zygaphophyseal joints - breasts anteriorly marked by opaque strands of fibrous tissue & more translucent fat. - both main bronchi (dark, air filled). - SVC with contrast just anterior to right bronchus - ascending & descending aorta. - structure of medium density looping from heart into lung field on left is pulmonary artery Pulmonary veins are seen in IMAGE 29)

QUESTION 8 Name the chamber of the heart which gives rise to the pulmonary trunk.

QUESTION 9 What is the gap in the image of the vertebra between body & zygaphophyseal joint seen at this level? What passes through this gap?

IMAGE 24 - look carefully at the small bronchi in the right lung where it is possible to see irregular cartilage plates as slightly more opaque structures.

IMAGE 25 - pulmonary trunk & right pulmonary artery - light grey curved structure (it is difficult to distinguish the junction).

IMAGE 29 - left atrium anterior to vertebral body receiving pulmonary veins (two on right enter the left atrium separately, the two on the left appear to have joined before entering left atrium (common arrangement), air in lobar bronchi.

ANAT3007/3907 - Applied Anatomy – Thorax Year 2019

7 IMAGE 30 - attachment of pericardium to sternum (can you suggest why this relationship is significant in cardiac surgery?) - the four chambers of the heart are now visible (positions may not be quite what you would expect!). You do not need to identify individual chambers in this screen.

IMAGE 34 - interventricular septum (oblique dark grey area across heart) Posterior to heart - descending aorta - azygos on right - oesophagus (medial to aorta, no obvious lumen - confirm by scrolling to IMAGE 37).

QUESTION 10 There is a tiny round structure, smaller than azygos, in IMAGE 34 between aorta & azygos . What is this structure?

IMAGES 39 - 41 - shadow of dome of right diaphragm. Note also that at these levels the lung surrounds the dome of the diaphragm The diaphragm is thin & is crossed in approximately one frame, - IVC is passing through diaphragm (anterolateral to oesophagus on the right). - identify oesophagus & aorta that are about to cross diaphragm

QUESTION 11 What is the number of the thoracic vertebra adjacent to the caval hiatus?

QUESTION 12 What is the organ immediately beneath the right dome?

QUESTION 13 Hemiazygos can be seen in IMAGE 40 - where is it?

ANAT3007/3907 - Applied Anatomy – Thorax Year 2019

8 2/2/06 Female 37 years CT Chest & Upper Abdomen + CONTRAST (in IVC) (THIRD ON CT LIST) SAGITTAL (Reformatted). Images are arranged from left (Image 2) to right (Image 58) IMAGE 1 Map of site of each CT scans. Note relationship of aorta, left atrium & bronchi IMAGE 13 - apex of heart.

QUESTION 14 Which part of the diaphragm is immediately beneath the heart?

IMAGE 15 - fissure of lung. You will need to adjust contrast & brightness to see this - look at the posterior level of ribs 2- 3 to see start of fissure.

QUESTION 16 Which lung is this & which fissure?

IMAGE 25 - aortic arch & thoracic aorta. Dark bronchus just below arch, pulmonary trunk just anterior to bronchus.

QUESTION 17 What are the 5 round anterior structures of medium density in anterior thoracic wall?

QUESTION 18 What are the small white spots within the costal cartilages? Are these normal? (Answer from Internet hint - check age of donor)

ANAT3007/3907 - Applied Anatomy – Thorax Year 2019

9 IMAGE 27 (approximately midline) - note the light vertical structures – left common carotid & left subclavian artery - coming off the arch of the aorta.

IMAGE 29 - 30 - Manubrium - body of sternum, - xiphoid process - trachea with cartilage - oesophagus posterior to trachea.

IMAGE 33 - SVC with contrast medium - left zygaphophyseal joints.

IMAGE 43 - lung fissures

ANAT3007/3907 - Applied Anatomy – Thorax Year 2019

10 2/2/06 Female 37 years (15/9/1968) CT Chest & Upper Abdomen + CONTRAST (in IVC) 37 Images SERIES 8 - CORONAL (Reformatted). Images are arranged from posterior (Image 2) to anterior (Image 37) IMAGE 1 Map of site of each CT scans.

IMAGE 10 - costocorporeal joints (best seen in mid thorax). Note in general that the articulation of a typical rib is with body of equivalent vertebra & body of the vertebra above. - intercostal muscles

IMAGE 14 - aorta - just to the left of the vertebrae

IMAGE 16 - aorta. Note relationship to oesophagus on right (recognise by air just visible in the superior part of the oesophageal lumen - left principle bronchus (anterior to aorta)

IMAGE 18 - trachea & principle bronchi - aorta passing through diaphragm.

IMAGES 20 - 21 - oesophagus & IVC passing through diaphragm

IMAGE 22 - intrapulmonary bronchi.

QUESTION 19 How did you identify the intrapulmonary bronchi & distinguish them from blood vessels?

ANAT3007/3907 - Applied Anatomy – Thorax Year 2019

11 IMAGE 27 - manubrium & articulation with clavicle & with costal cartilage of rib 1.

QUESTION 20 Which is clavicle & which is costal cartilage?

IMAGE 35 - sternum articulating with costal cartilages. - internal intercostal vessels....