These Spaces Have Potential: Teaching Students About Anatomical Spaces

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These Spaces Have PotentialTeaching Students
About Anatomical Spaces

• Arthur F. Dalley
• Vanderbilt University Medical Center
• Nashville, Tennessee

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Anatomical Spaces

• True potential spaces only become spaces in
  abnormal situations
• Pathological cleavage planes
• Arachnoid-dura interface
• (often erroneously called subdural space)
• Sub-cuticular layer of epidermis
• Friction/sunburn blisters
• Intra-retinal space
• Detached retina

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Anatomical Spaces

• Anatomical potential spaces
• Serous (mesothelium-lined) spaces
• occupied by a capillary-layer of fluid
• Pleural cavity
• Peritoneal cavity
• Tunica vaginalis
• Joint (synovial) cavity
• Tendon sheaths bursae

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Anatomical Spaces

• Actual (fluid-occupied) spaces
• Subarachnoid space
• (similar to the major anatomical potential spaces
  in that the leptomeninges have a parietal and a
  visceral layer)
• Anterior chamber of eyeball
• Urinary bladder
• Gallbladder

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Moore Dalley Clinically Oriented Anatomy 5th
ed., Fig I.16A, p. 27
Anatomical potential spaces are
highly exaggerated in schematic diagrams
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Suprapatellar bursa
Prepatellar bursa
Joint cavity injected with wax enclosed by
synovial membrane
Artificial means must be used in dissection to
demonstrate their existence
Grants Atlas 12th ed. Fig. 5.47B, p. 414
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The moment an anatomical potential space is
violated, in dissection, surgically, or
endoscopically, it is no longer potential and
loses its unique characteristics.
Moore Dalley Clinically Oriented Anatomy 5th
ed., Fig B1.1, p. 80
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Moore Dalley Clinically Oriented Anatomy 5th
ed., Fig 1.23C, p. 112
The fist in a balloon analogy has traditionally
and effectively been used to demonstrate a
structure surrounded by, yet external to, an
anatomical potential space.
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Moore Dalley Clinically Oriented Anatomy 5th
ed., Fig 1.23C, p. 112
Important lessons here include the manner in
which the pleural fluid provides both (1)
lubrication for mobility and (2) surface tension
to enable lung expansion and prevent collapse.
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Moore Dalley Clinically Oriented Anatomy 5th
ed., Fig I.10B, p. 18
When performed as a demonstration, the most
teachable moment is step d (not shown), when
the balloon is collapsed around your fist.
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Moore Dalley Clinically Oriented Anatomy 5th
ed., Fig B1.8, p. 118
Unfortunately(?), your fist does not collapse
when the surrounding membrane is ruptured and the
surface tension is broken, so the analogy is
limited.
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Tendon sheaths can be especially challenging
conceptually
Moore Dalley Clinically Oriented Anatomy 5th
ed., Fig I.10A, p. 18
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End of Show

• All illustrations used with the authors
  permission.