The Five Anatomical Caves of the Human Brain: A Comprehensive Scientific Review

Abstract

The term “caves” (Latin: cava) in neuroanatomy refers to fluid-filled or potential spaces within the brain, often remnants of embryonic development. A pedagogical mnemonic in radiology and neurosurgery highlights five key structures: the cavum septum pellucidum (CSP), cavum vergae (CV), cavum veli interpositi (CVI), and the paired Meckel’s caves (left and right, also known as cavum trigeminale). These are frequently encountered on neuroimaging, primarily as incidental findings. While most are benign, their persistence or enlargement can signal neurodevelopmental anomalies, psychiatric disorders, or pathologies like trigeminal neuralgia. This review synthesizes current literature on their embryology, anatomy, physiological roles, radiological features, and clinical implications, emphasizing differential diagnoses and management. High-resolution MRI remains pivotal for evaluation.

Introduction

In the intricate architecture of the human brain, fluid-filled cavities serve as echoes of ontogeny, facilitating cerebrospinal fluid (CSF) dynamics or neural protection. The “five caves” mnemonic—CSP (“fifth ventricle”), CV (“sixth ventricle”), CVI, and bilateral Meckel’s caves—unifies midline ventricular variants with a skull base dural recess.[1][2] Though not all are true ventricles (lacking ependymal lining), they pose diagnostic challenges on MRI and CT, mimicking cysts or masses.[5] Embryologically, they arise from incomplete fusion or dural invaginations, with prevalence varying by age and modality.[15] Clinically, associations span asymptomatic variants to hydrocephalus, schizophrenia, and cranial neuropathies.[9][12]

Embryology and Development

Brain cava emerge during the 8th–12th gestational weeks as the telencephalon cleaves.[17] The septum pellucidum forms as paired laminae from the commissural plate, initially separated by CSF filtrate; fusion proceeds posteroanteriorly from ~24 weeks, obliterating the CSP in 85–90% by 6 months postpartum.[3][17] CV, a posterior extension, closes earlier (97% by term).[6] CVI derives from tela choroidea separation in the third ventricle roof, persisting as a cistern in ~90% of adults.[4] Meckel’s caves, from meninx primitiva, invaginate durally around the trigeminal ganglion by week 10, forming bilateral pouches continuous with subarachnoid space.[13]

Anatomy and Functions

1. Cavum Septum Pellucidum (CSP)

A midline slit (1–3 mm) between septal laminae, superior to the fornix and anterior to Monro’s foramina.[2] It harbors CSF filtrate, non-communicating with ventricles. Functionally vestigial, it marks limbic maturation; part of the limbic system, influencing emotion/memory via septal projections.[9] Prevalence: 10–20% adults.

2. Cavum Vergae (CV)

Posterior CSP extension beyond fornix columns, anterior to callosal splenium; triangular, always with CSP (termed CSPV).[6] Passive CSF reservoir, buffering midline pressures; no active role. Prevalence: 2–5%.

3. Cavum Veli Interpositi (CVI)

Triangular cistern in third ventricle roof (tela choroidea), superior to pineal/internal cerebral veins, inferior to fornices.[1][4] Communicates with subarachnoid space; supports choroid plexus/veins, aiding CSF flow. Prevalence: ~90% (small).

4–5. Meckel’s Caves (Cavum Meckelii/Trigeminale, Bilateral)

Paired dural pouches in middle cranial fossa (petrous apex), posterior to cavernous sinus.[13][18] House trigeminal ganglion (Gasserian), CN V roots/divisions, and CSF sleeve. Protects sensory/motor fibers for facial sensation/mastication; cushions neurovascular contacts. Prevalence: 100%.

Structure Location Typical Dimensions Contents Embryonic Origin
CSP Midline, septal leaflets 1–3 mm slit CSF filtrate Commissural plate laminae
CV Posterior to CSP/fornix Triangular, <10 mm CSF Delayed posterior fusion
CVI Third ventricle roof Triangular, <1 cm CSF, veins, choroid Tela choroidea separation
Meckel’s Cave (L/R) Middle fossa, petrous apex 5–10 mm pouch Trigeminal ganglion, CN V, CSF Meninx primitiva invagination

Radiological Features

High-resolution MRI (T2/CISS sequences) excels for delineation.[18] CSP/CV: CSF-isointense midline slits, <10 mm anteroposterior; sagittal views distinguish from fornix.[2] CVI: Winged cistern superior to pineal, veins traversing.[1] Meckel’s: CSF pouches with “feathered” CN V roots; bilateral asymmetry flags pathology.[18]

Clinical Significance and Pathology

Most CSP/CV/CVI are incidental; enlarged (>10 mm) cysts cause hydrocephalus via Monro obstruction.[9] CSP associated with schizophrenia (OR 1.5–2), fetal alcohol syndrome, and chronic traumatic encephalopathy.[9][21] CVI mimics pineal cysts; dilated forms rarely cause tectal compression.[1] Meckel’s caves are central in trigeminal neuralgia, schwannomas, perineural tumor spread, and inflammatory syndromes.[13][18]

Overall Summary 

The five anatomical caves of the human brain play essential roles in:

  • Neurodevelopment and midline embryology
  • CSF circulation and intracranial pressure buffering
  • Sensory processing and cranial nerve stability
  • Memory, executive function, and emotional regulation

Their clinical importance spans neurology, psychiatry, neurosurgery, radiology, and developmental neuroscience.

Conclusion

These cava underscore embryonic-brain transitions: benign harbors in most individuals, yet potential harbingers of pathology when enlarged or infiltrated. Incidental findings warrant reassurance; symptomatic or Meckel’s lesions demand prompt intervention.

References

  1. Al-Sharydah, Abdulaziz Mohammad, et al. “A Unique Finding of Cavum Velum Interpositum Colloid-Like Cyst and Literature Review of a Commonplace Lesion in an Uncommon Place.” International Journal of General Medicine, vol. 11, 2018, pp. 301–305, doi:10.2147/IJGM.S169018.
  2. Amini, Behrang, et al. “Cavum Septum Pellucidum.” Radiopaedia.org, 23 May 2025, radiopaedia.org/articles/cavum-septum-pellucidum-3.
  3. Born, Christoph M., et al. “The Septum Pellucidum and Its Variants. An MRI Study.” European Archives of Psychiatry and Clinical Neuroscience, vol. 254, no. 5, 2004, pp. 295–302, doi:10.1007/s00406-004-0496-z.
  4. D’Addario, Vincenzo, et al. “Cavum Veli Interpositi Cyst: Prenatal Diagnosis and Postnatal Outcome.” Ultrasound in Obstetrics & Gynecology, vol. 34, no. 1, 2009, pp. 52–54, doi:10.1002/uog.6419.
  5. Epelman, Monica, et al. “Differential Diagnosis of Intracranial Cystic Lesions at Head US.” RadioGraphics, vol. 26, no. 1, 2006, pp. 173–196, doi:10.1148/rg.261055033.
  6. Gaillard, Frank, et al. “Cavum Vergae.” Radiopaedia.org, 28 Dec. 2024, radiopaedia.org/articles/cavum-vergae.
  7. Ho, Belinda C., et al. “Cavum Septum Pellucidum in First-Episode Schizophrenia.” Journal of Neuropsychiatry and Clinical Neurosciences, vol. 12, no. 3, 2000, pp. 344–349, doi:10.1176/jnp.12.3.344.
  8. Kamel, Hatem A., and John Toland. “Trigeminal Nerve Anatomy.” American Journal of Roentgenology, vol. 176, no. 1, 2001, pp. 247–251, doi:10.2214/ajr.176.1.1760247.
  9. Malhotra, Ajay, et al. “Neuroimaging of Meckel’s Cave in Normal and Disease Conditions.” Insights into Imaging, vol. 9, no. 4, 2018, pp. 499–510, doi:10.1007/s13244-018-0604-7.
  10. Oktem, Huseyin, et al. “Prevalence of Septum Pellucidum Variations.” Open Access Library Journal, vol. 5, no. 11, 2018, e4991, doi:10.4236/oalib.1104991.
  11. Rakic, Pasko, and Paul I. Yakovlev. “Development of the Corpus Callosum and Cavum Septi in Man.” Journal of Comparative Neurology, vol. 132, no. 1, 1968, pp. 45–72, doi:10.1002/cne.901320103.
  12. Rubinstein, David, et al. “Trigeminal Nerve and Ganglion in the Meckel Cave.” Radiology, vol. 193, no. 1, 1994, pp. 155–159, doi:10.1148/radiology.193.1.8090884.
  13. Shenton, Martha E., et al. “A Review of MRI and DTI Findings in Mild Traumatic Brain Injury.” Brain Imaging and Behavior, vol. 6, no. 2, 2012, pp. 137–192, doi:10.1007/s11682-012-9156-5.