Friday 22 Apr
What is Cross Sectional Anatomy?
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Cross Sectional Anatomy Dr. Elwin R. Tilson, R.T.(R)(M)(QM)(CT), FAEIRS
Armstrong Atlantic State University
Savannah, GA
elwin.tilson@armstrong.edu
'Sectional' Can Mean Several Things
Why Do I Need To Know Anything About It?
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To Help You Understand, Think About Meat Loaf •
•
•
•
Axial
Coronal
Sagittal 3D
Sliced Meat Loaf • We can slice it regularly, top and bottom, or long ways to see what is inside
• We do the same thing with data sets in CT, MRI Sonography and other modalities
MRI, Sonography, and other modalities
Not him! A real meat loaf with lots of vegetables in it
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Friday 22 Apr
Axial
Which Orientation is Which?
• Margins are Right/Left and Anterior/Posterior
• Radiographs 'squash' the anatomy into one image
• Cross sectional images have a defined thickness – like a slab of meatloaf
a slab of meatloaf
A
R
L
P
Coronal
Sagittal
• Margins are Superior/Inferior and Right/Left
• A bit like an AP image but it's NOT!
• It shows only a slab of the anatomy
• Margins are Anterior/Posterior and Superior/Inferior
• A bit like a lateral image but it's NOT!
• It shows only a slab of the anatomy
S
S
R
L
A
I
Upside Down, Inside Out, Backwards Thinking
• In order to understand cross sectional you have to have a new mindset
• Recall: slices are virtual 'slabs' of anatomy that cut through the body
cut through the body
– You don’t see what is outside that slab
• It is too hard to 'memorize' the anatomy
• Students need a 'system' to think about the body so what is on the image makes sense
P
I
Teaching Yourself Cross Sectional Anatomy
• Step 1: Know what is suppose to be there –
divide the body into sections
– Head
– Neck/Face
– Chest
– Abdomen/Pelvis
– Extremities
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Friday 22 Apr
Teaching Yourself Cross Sectional Anatomy
• Step 2: Know where is what – Smaller structures and their relationships to major structures
• Step 3: Think 3‐Dimentionally Step 3: Think 3 Dimentionally
Sounds Simple… And It Is
• As long as you know your general anatomy
• As long as you know how structures are arranged relative to each other
• As long as you think 3D
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– Rotate the anatomy in your head so it is the same orientation as the image
• Step 4: Details, details, details – Relate details to big objects
Step 2: List the Major Structures in a Section
• Boney Structures
Step 1: The Chest
–
–
–
–
Spine
Ribs
Sternum
Clavicle
• Other Soft Tissue
– Lungs
– Trachea
– Esophagus
• Heart and major Blood vessels
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–
–
–
Step 2: Relationships – Boney Structures
•
•
•
•
Spine: T‐1 to T‐8/12 due to diaphragm motion
Scapula: Posterior T1 – T7
Sternum: Anterior to heart T‐3/4 to T‐10
Clavicle: Anterior T‐3 to T1 at shoulder
Clavicle: Anterior T‐3 to T1 at shoulder
Heart
Aortic Arch
Descending Aorta
Pulmonary Arteries
Step 2: Relationships – Heart and Blood Vessels
• Heart: Anterior and slightly left of midline
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Friday 22 Apr
Step 2: Relationships – Heart and Blood Vessels
• Aortic Arch: T3 to top of heart, posterior and superior then inferior
• Descending Aorta: Posterior and left of spine
Step 2: Relationships – Lungs, Airways, etc.
• Trachea: Midline and bifurcates (carina) at T‐
4/5 and pulmonary artery
• Esophagus: Midline behind trachea and then behind Lt Atrium
behind Lt. Atrium
Step 3: Chest Example Trachea Step 2: Relationships – Lungs, Airways, etc.
• Lungs: 3 lobes Rt and 2 lobes Lt. T1‐T10/11
Step 3: Orientation
• In your head, rotate the 3D ‘image’ of the body part to the same orientation as the slice
• Now, visualize where the major structures are to each other
to each other
• Finally, relate other structures to major structures.
Step 3: Chest Example Aorta
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Friday 22 Apr
Step 4: Details on Chest
Step 3: Chest Example Pulmonary A. •
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Suprasternal (jugular) notch
Sternal angle
Xiphoid process
Apex
Subclavian arteries
Subclavian arteries
Azygos V.
Vetrebal A.
Mediastinum
– Anterior Mediastinum
– Middle Mediastinum
– Posterior Mediastium
Anterior Mediastinum
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•
•
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Areolar tissue
Lymphatic vessels Anterior mediastinal lymph glands
Branches of the internal mammary artery
Thymus (in infants and young children)
Bony Thorax‐
• Heart enclosed in the pericardium
• Ascending aorta
• Lower half of the superior vena cava with the yg vein opening into it
p
g
azygos
• Bifurcation of the trachea and the two bronchi
• Pulmonary artery dividing into its two branches
• Right and left pulmonary veins
• Pulmonary cavities
• Common carotid artery
Bony Thorax‐ (CT Axial Image)
(CT Axial Images)
1st and 2nd Ribs
Clavicles
Middle Mediastinum
Sternum‐
Manubrium
Right Scapula
Left Humeral Head
Left
Scapula
Vertebral body
Rib
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Friday 22 Apr
Bony Thorax
Bony Thorax‐ (MRI Sagittal Image)
Ribs
Scapula
Sternum
Sternum
St
The Lungs
Img
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The Lungs
Img
2
RT Upper lobe
RT Middle lobe
RT Middle lobe
RT Lower lobe
Trachea
Bifurcation into Lt and Rt bronchi
The Lungs
The Lungs‐
Trachea (inner ring is
Endotracheal tube (ET Tube))
Img
3
Right
Primary
Bronchus
Trachea superior to bifurcation
MRI acquired images
Trachea Bifurcating Rt and Lt
Left Primary
Bronchus
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Friday 22 Apr
The Heart‐
deoxygenated venous blood flows into the heart’s Right Atrium via The Heart‐
From the Right Atrium, blood flows through the tricuspid valve the superior vena cava.
Superior Vena Cava
into the Right Ventricle.
Right Atrium
Right Atrium
The Heart‐
Blood flows through the right and left pulmonary arteries and is taken into the lungs for oxygenation.
Right Ventricle
The Heart‐
Right Ventricle
The pulmonary veins take the blood back to the heart from the lungs and it enters the Left Atrium, through the mitral valve, and into the Left Ventricle.
Pulmonary Trunk
AA
Rt Pulmonary
Artery
The Heart‐
Left
Ventricle
l
Lt Pulmonary
Artery
SVC
Left Atrium
DA
The Heart
from the Left Ventricle blood is ejected out and into the ascending aorta. This begins circulation.
Interventricular
Septum
Interventricular
Septum
RT Ventricle
Left Ventricle
LT Ventricle
RT Atrium
LT Atrium
Descending
Aorta
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Friday 22 Apr
The Heart‐
MRI images. Two‐chamber view/ short axis (left image); Four‐
chamber/ long axis view ( right image)
Two Chamber short axis view
The Heart‐
MRI coronal gradient echo image (left); CT with contrast, coronal reconstruction image (right). Note‐ the left ventricle is more anterior than the left atrium. Four Chamber long axis view
Aortic arch
SubclavianArteries
Interventricular
Septum
RV
RA
RV
LV
LV
LV
Interventricular
Septum
Left
Ventricle
The Heart‐
Heart Valves
MRI sagittal images
Tricuspid
Valve
LV
Left Atrium
Bicuspid (Mitral)
Valve
LA
LA
RV
Important Vessels
Important Vessels
AA‐ ascending aorta DA‐ descending aorta SVC‐ superior vena cava AAr‐ aortic arch
AAr
AA
SVC
DA
DA
Azygos
Vein
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Friday 22 Apr
Important Vessels
Rt Brachiocephalic
Artery
Lt Common Carotid
Artery
Superior Vena Cava
Important Vessels
Left
Pulmonary
Artery
Ascending Aorta
Lt Subclavian
Artery
Right
Pulmonary
Artery
Thymus‐
Important Vessels
found immediately behind the manubrium. Part of the endocrine system.
Inferior Vena Cava
Step 2: Major Structures
STEP 1: The Abdomen
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Liver
Stomach
Spleen
Descending Aorta
Descending Aorta
IVC
GB
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Pancreas
Kidneys
Small Bowel
Colon
Bladder
Rectum
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Friday 22 Apr
Step 2: Relationships – Upper Abdomen
• Liver: Top Right Margin. Very long and may cross midline. Average right lobe T9‐L3.
• Stomach: Top Left from Stomach: Top Left from
midline. Fundus T10. Opening T11/12. Pylorus L1.
• Spleen: Top Left at Margin just lower than stomach. T10‐L1.
Step 2: Relationships – Upper Abdomen
• GB: Approximately midpoint on underside of liver. Inferior margin L2. Anterior at same plane as IVC.
• Pancreas: Body T12. Head g
right of midline. Tail almost touching spleen.
• Kidneys: Right usually higher than left. Right T11‐
L3. Left T12‐L3. Both just lateral to vertebra. • Transverse colon: Splenic Flexure T12. Hepatic flexure L2 Step 2: Relationships – Pelvis
Step 2: Relationships – Upper Abdomen
• Descending Aorta: Continues just left of midline. Diaphragm to L5.
– Keep in mind: Arteries are small and high pressure
small and high pressure.
• IVC: Base of heart (T9) to L5. Anterior and right of Descending Aorta.
– Keep in mind: Veins are large and low pressure
Step 2: Relationships – Lower Abdomen
• Small Bowel: Superior duodenum T12 • Ascending Colon: Ileocecal Valve L5
Step 3: Abdomen Example Bladder
• Iliac Crest: L4 • Bladder: Midline. Box shaped on images. • Sigmoid Colon: S2 both Sigmoid Colon: S2 both
sides of midline
• Rectum: Midline. Just anterior to coccyx
• Uterus: Midline x2 above bladder
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Friday 22 Apr
Step 4: Details on Abdomen Blood vessels
Step 3: Abdomen Example GB
• Celiac A. T12
• Superior Mesenteric A. L1
• Inferior Mesenteric A. L3
• Renal A. L1/2
• Inferior phrenic A. T12 • Descending Aorta Bifurcation into iliac A. L4/5
Left Adrenal A. T12‐L1 Inferior phrenic V. T8
Hepatic V. T8
Suprarenal V. L1
Renal V. L1
Gonadal V. L2
Common iliac V. L5
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Image 4
Image 1
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1 = Descending Aorta
2 = Vertebra
3 = Rib
4 ‐ Sternum
5 = Lt ventricle 6 = Rt ventricle
7 = Liver
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1 = Descending Aorta
2 = Vertebra
3 = Rib
4 ‐ Sternum
5 = muscle
6 = Heart 6
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Image 7
Image 10
1 = Descending Aorta
2 = Vertebra
3 = Rib
4 ‐ Sternum
5 = Lt ventricle 6 = Rt ventricle
7 = Liver
8 = Vena Cava
9 = Spleen
10 = Stomach
1 = Descending Aorta
2 = Vertebra
3 = Rib
4 ‐ Liver
5 = I. Vena Cava
6 = Spleen
7 = Stomach
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Friday 22 Apr
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Image 13
Image 16
1 = Descending Aorta
2 = Vertebra
3 = Rib
4 ‐ Liver
5 = I. Vena Cava
6 = Spleen
7 = Stomach
8 = Kidney
1 = Descending Aorta
2 = Vertebra
3 = Pancreas
4 ‐ Liver
5 = I. Vena Cava
6 = Spleen
7 = Stomach
8 = Kidney
9 = Spleenic A.
Arrow = Adrenal
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Image 22
1 = Descending Aorta
2 = Vertebra
3 = Pancreas
4 ‐ Liver
5 = I. Vena Cava
6 = Spleen
7 = Stomach
8 = Kidney
9 = Renal Vein
10 = D. Colon
11 = Sm bowel
11 = Sm. bowel
1 = Descending Aorta
2 = Vertebra
3 = Liver
4 = IVC
5 = Stomach
6 = Kidney
7 = A. Colon
8 = D. Colon
9 = Sm. bowel
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Image 25
Image 28
1 = Descending Aorta
2 = Vertebra
3 = IVC
4 = Stomach
5 = Kidney
6 = A. Colon
7 = D. Colon
8 = Sm. bowel
1 = Descending Aorta
2 = Vertebra
3 = IVC
4 = T. Colon
5 = A. Colon
6 = D. Colon
7 = Sm. bowel
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Friday 22 Apr
Image 32
Image 31
1 = Descending Aorta
bifracation
2 = Vertebra
3 = IVC
4 = T. Colon
5 = A. Colon
6 = D. Colon
7 = Sm. Bowel
8 = Psoas M.
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1 = Iliac A.
2 = Vertebra
3 = IVC bifurcation
4 = T. Colon
5 = A. Colon
6 = D. Colon
7 = Sm. Bowel
8 = Psoas M.
9 = Iliac Creast
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1
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3
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<‐10 7
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Image 37
Image 40
1 = Iliac A.
2 = Vertebra
3 = Iliac V.
4 = T. Colon
5 = A. Colon
6 = D. Colon
7 = Sm. Bowel
8 = Psoas M.
9 = Pelvis
10 = Ureter 1 = Ureter 2 = Sacrum
3 = D. Colon
4 =Sm Bowel
5 =Psoas M.
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Image 43
Image 46
1 = Ureter 2 = Sacrum
3 = Sigmoid Colon
4 =Sm Bowel
1 = Ureter 2 = Sigmoid Colon
3 =Sm Bowel
4
3
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2
3
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<‐‐1
<‐‐1
<‐‐1
2
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Friday 22 Apr
Image 49
Image 52
1 = Ureter 2 = Rectum
3 = Sigmoid Colon
4 =Bladder
5 = Uterus 1 = Ureter 2 = Rectum
3 = Bladder
3A = Contrast in Bladder
4 = Uterus 3
4
3A
5
4
1‐‐>
3
3
<‐‐1
2
2
Image 55
Image 58
1 = Rectum
2 = Bladder
3 = Uterus 1 = Rectum
2 = Bladder
3 = Symphysis
3
2
2
3
1
1
Image 60
1 = Rectum
2 = Symphysis
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Step 1: The Head
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Friday 22 Apr
Step 2: Major Structures
• The Cerebrum
– Frontal Lobe
– Parietal Lobe
– Occipital Lobe
Occipital Lobe
– Temporal Lobe
Step 2: Major Structures
• The Cerebellum
• Limbic System
– Thalamus
– Hypothalamus
H
h l
– Amygdala
– Hippocampus
Step 2: Major Structures
• Brain Stem – Midbrain
– Pons
– Medulla
• Basal Ganglia
• Corpus callosum
Step 2: Relationships • Cerebellum – Located behind pons, in posterior section of cranial cavity.
• Cerebral cortex
Cerebral cortex
– Outer layer of cerebrum
• Cerebrum
– Largest part of brain.
Step 2: Relationships • Corpus callosum
– Bridge of nerve fibers that connects one cerebral hemisphere with the other
• Hypothalamus
– Small mass below the thalamus; forms floor and part of lateral walls of third ventricle
• Medulla oblangata
– Lowermost portion of brainstem
Step 2: Relationships • Midbrain
– Located at upper end of brainstem.
– Connects pons, and cerebellum with cerebrum
• Pons
– Lies anterior to cerebellum and between midbrain and medulla.
• Thalamus
– Located in center of cerebrum
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Friday 22 Apr
Step 3: Brain Example Tumor
Step 3: Head Example Orbit
Step 3: Head Example IAC
Step 4: Details
Maxillary Sinus
Maxillary Sinus
Foramen Magnum
Vertebral A.
Spinal Cord
Skull Base
Skull Base
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Friday 22 Apr
Maxillary Sinus
Zygomatic
Arch
Zygomatic
Arch
Ethmoid Sinus
Mandibular
Condyle
Medulla Oblongata
Cerebellum
Cerebellum
Ethmoid Sinus
Ethmoid Sinus
Globe of the Eye
Sphenoid Sinus
Sphenoid Sinus
Temporal Lobe
Mastoid Air Cells
Cerebellum
Cerebellum
Ethmoid Sinus
Frontal Lobe
Sphenoid Sinus
Basilar Artery
Temporal Lobe
Dorsum Sella
Temporal Lobe
Cerebral Peduncle
Aqueduct of Sylvius
Cerebellum
Fourth Ventricle
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Friday 22 Apr
Falx Cerebri
Falx Cerebri
Anterior Horn Lateral Ventricle
Gray Matter
Caudate Nucleus
White Matter
Third Ventricle
Thalamus
h l
Body of Lateral Ventricle
Sylvian
Fissure
Parietal
Bone
Parietal Lobe
Posterior Horn Lateral Ventricle
Superior Sagittal Sinus
T1 Weighted MRI Sagittal (dark CSF)
T1 Weighted MRI Sagittal (dark CSF MRI)
Skull
Ventricle
Frontal Lobe
Thalamus
Parietal
Lobe
Cerebral (Sylvian)
aqueduct
Cerebellum
T1 Weighted MRI Coronal
Maxillary sinus
T1 Weighted MRI Coronal
Sylvian
fissure
Hippocampal
Formation
Falx Cerebri
Temporal Lobe
Thalamus
8th Nerve
Pons
8th Nerve
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Friday 22 Apr
T1 Weighted MRI Coronal
Internal Auditory
canal
Study Tips
8th cranial nerves
Odontoid process, C2
Learning Pyramid
• Activities help you learn • Don’t just try to ‘memorize’ it!
Teaching Aids
• For Mac & iPad owners: Osirix
– Octogonal (3‐
orientation) R
Reconstructions
t ti
– 3D Modeling
Teaching aids
• Visible Man Model
• Play Dough
• Labeling Images
Web sites
• Excellent introduction to cross sectional anatomy site. Covers Head, Chest, Abdomen. • http://www.med.wayne.edu/diagRadiology/Anatomy_Modules/Pa
ge1.html
• Good Introduction to CT Brain anatomy. Only major structures labled
structures labled. • http://www.urmc.rochester.edu/smd/Rad/neuroanatomy/headCT
_anatomy.htm
• CT brain anatomy. Very informative visually. About 65 structures identified. • http://www.neurosurvival.ca/ComputerAssistedLearning/readingC
Ts/anatomy_guide/alpha.htm
• The Whole Brain Atlas More detail then you might need but amazing site
• http://www.med.harvard.edu/AANLIB/home.htm
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Friday 22 Apr
Web sites
• Gray’s Anatomy online • http://www.bartleby.com/107/ • CT is Us site. Good teaching helps. • http://www.ctisus.com/
http://www ctisus com/
• National Library of Medicine Visible Human Project. Actual thin slices of cadavers reconstructed as 3D. Can be sliced any way you like. • http://anatquest.nlm.nih.gov/AnatQuest/AwtCsViewer/
aq‐cutaway.html
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