Foramen Lacerum is bounded infront by the body and adjoining greater wing of sphenoid, behind by the apex of petrous temporal bone and medially by basilar part of occipital bone. The anterior wall presents posterior opening of pterygoid canal for the passage of pterygoid vessels and nerve and its posterior wall is occupied by the anterior opening of carotid canal which transmits internal carotid artery surrounded by a plexus of sympathetic nerves and veins. Upper opening of the foramen conveys internal carotid artery into the middle cranial fossa; the lower opening is closed in the recent state by a plate of cartilage. Structures passing through the lower opening are meningeal branches of ascending Pharyngeal artery and emissary veins communicating with the cavernous sinus.¹

The  Foramen  Lacerum  has  been  a channel for the  intracranial  spread  of  various  malignant  tumours, such as nasopharyngeal carcinoma,  adenoid  cystic  carcinoma,  juvenile angiofibroma, malignant melanoma, and lymphoma.²  In the case of nasopharyngeal carcinoma, the incidence rates of tumour spread involving the Foramen Lacerum range from 47.8% ^3,4  to as high as 53.2%⁵ . The Foramen Lacerum has also been associated with the spread of infection to the intracranial space, and reports of cavernous sinus thrombosis are well documented.⁶

Variations in the size of the foramen and its obliteration by the ossification of fibrocartilaginous tissue can result in compression of structures passing through the foramen like the deep petrosal nerve, the greater petrosal nerve, the vidian nerve etc. In such cases, procedures like   neurectomy and decompression are necessary to give relief to the patient. Hence, knowledge about morphometric variations in the Foramen Lacerum can improve the outcome of such surgeries.

AIMS AND OBJECTIVES:

(1) To compare the Transverse diameter of the Foramen Lacerum on both sides of the skull

(2)  To compare the Anteroposterior diameter of the Foramen Lacerum on both sides of the skull

Figure 1: Measurement of foramen lacerum.

Study Design

This cross-sectional study was conducted in the Department of Anatomy and the Department of Forensic Medicine at Guntur Medical College, Guntur, Andhra Pradesh, India, from September to December 2024.

Sample Selection

A total of 36 dry skulls were selected for the study. These skulls were obtained from the Department of Anatomy and the Department of Forensic Medicine. The sample consisted of 21 male skulls and 15 female skulls, with a total of 72 Foramen Lacerum (36 from each side of the skull). Only ossified dry skulls that were free from defects or deformities were included in the study, while damaged skulls were excluded.

Inclusion and Exclusion Criteria

Inclusion Criteria: Ossified dry skulls with no visible defects or deformities.

Exclusion Criteria: Damaged skulls with visible fractures or deformities.

Morphometric Measurements

The morphometric parameters of the Foramen Lacerum were measured using a digital Vernier caliper, which was calibrated prior to the measurements to ensure accuracy. The following measurements were taken:

Transverse Diameter: The width of the Foramen Lacerum was measured from one side to the other.

Anteroposterior Diameter: The length of the Foramen Lacerum was measured from the anterior to the posterior edge of the foramen.

These measurements were conducted on both sides of the skulls, resulting in a total of 72 Foramen Lacerum measurements (36 on each side).

Data Collection

All measurements were taken by a single examiner to minimize inter-rater variability. Each measurement was repeated three times, and the average of the three measurements was used for data analysis.

Statistical Analysis

The collected data was analyzed using descriptive statistical methods. The measurements of the transverse and anteroposterior diameters of the Foramen Lacerum were compared between the male and female skulls, and between the right and left sides. The data was presented as mean ± standard deviation.

Ethical Considerations

Ethical approval for the study was obtained from the Institute Ethics Committee under reference number GMC/IEC/036/2024. The study was conducted in accordance with the ethical guidelines set by the Institute Ethics Committee. Informed consent was obtained from the relevant authorities for the use of skulls in the study. All personal and identifying information related to the skulls was kept confidential.

36 skulls were included in the present study. The Foramen Lacerum was studied on both sides for each skull, a total of 72 Foramen Lacerum were studied. The measurements of the Transverse diameter and AnteroPosterior diameter of the Foramen Lacerum were measured and recorded [Table/Fig -1] on the right and left side separately. In the present study the mean Transverse diameter on the right side is 6.41mm and on left side 6.52 mm in male skulls. The mean Transverse diameter on the right side is 5.72mm and on left side 5.76 mm in female skulls. In the present study the mean AP diameter on the right side is 6.71mm and on left side 6.38 mm in male skulls, the mean AP diameter on the right side is 4.69 mm and on left side 5.23 mm in female skulls.

Figure2: Measurement of foramen lacerum

Table/ Figure -3showing the measurements of foramen lacerum in male skulls

Table/ Figure-4. showing the measurements of foramen lacerum in female skulls

The present study was conducted in the Department of Anatomy and Department of Forensic Medicine at Guntur Medical College, Guntur, Andhra Pradesh, India, to study the morphometry  of the foramen lacerum in dry skulls. There are less number of studies conducted on foramen lacerum till now. Nevertheless, it is an important anatomical structure as it is considered to be a conduit for carcinomas into the cranium, both benign and malignant ⁷. Moreover, it lies at the intersection of the sagittal and coronal planes but has not been widely utilized in intracranial surgeries until recently. ^8,9

In the present study the mean Transverse diameter on the right side is 6.41mm and on left side 6.52 mm in male skulls. In study conducted by Sanghpriya Chaudhary and et al Dehradun, Uttarakhand India the mean Transverse diameter on right side is 6.14mm and on left side is 6.20 mm in male skulls. In the present study the mean Transverse diameter on the right side is 5.72 mm and on left side 5.76 mm in female skulls. In study conducted by Sanghpriya Chaudhary and et al Dehradun, Uttarakhand India, the mean Transverse diameter in female skulls on right side is 5.88 mm and on left side is 5.88 mm. In the study conducted by Abd EL Naeem A. Sohag University Upper Egypt the mean Transverse diameter is on right side is 6.85mm and on left side is 6.59 mm.

Table: 5

In the present study, the mean transverse diameter of the foramen lacerum was slightly larger on the left side than right side in both male & female skulls.  This coincides with the previous studies conducted by Sanghpriya Chaudhary and et al where the mean transverse diameter of the foramen lacerum was slightly larger on the left side than right side in males where as in females there is no difference.

In the present study the mean AP diameter on the right side is 6.71mm and on left side 6.38 mm in male skulls. In the study conducted by Sanghpriya Chaudhary and et al¹⁰ Dehradun, Uttarakhand, India the mean AP diameter is on right side is 6.26mm and on left side is 6.24mm in male skulls. In the present study the mean AP diameter on the right side  is 4.69 mm and on left side 5.23 mm in female skulls In the study conducted by Sanghpriya  Chaudhary and et al¹⁰ Dehradun, Uttarakhand India the mean AP diameter is on right side is 4.97 mm and on left side is  5.40 mm in female skulls. In the study conducted by Abd EL Naeem A.¹¹  Sohag University Upper Egypt the mean AP diameter is on right side is 10.89 mm and on left side is  10.88mm.

Table: 6

In the present study, the mean AP diameter of the foramen lacerum was slightly larger on the RIGHT side than LEFT side in male skulls.  This coincides with the previous studies conducted by Sanghpriya Chaudhary and et al where the mean AP diameter of the foramen lacerum was slightly larger on the RIGHT side than LEFT side in males.  In the present study the mean AP diameter is slightly larger on left side than on right side in female skulls which coincides with Sanghpriya Chaudhary and et al.

The mean AP diameter in the present study is smaller than in the the study conducted by Abd EL Naeem A. Sohag University Upper Egypt, which could be attributed to racial and geographical differences^11. As there is high prevalence of tumor spread to the intracranial space through foramen lacerum, there is a need of more studies to be conducted to analyze the morphometric variations in different geographical regions, genders, and races. Imaging-based clinical studies are useful to studythe size and shape of the foramen lacerum which are useful in recent advances of skull base surgeries and for the middle cranial fossa approaches.

The mean transverse diameter of the foramen lacerum was slightly larger on the left side than right side in male skulls. The mean transverse diameter is slightly larger on left side than on right side in female skulls. The mean AP diameter of the foramen lacerum was slightly larger on the Right side than Left side in male skulls.  The mean AP diameter is slightly larger on left side than on right side in female skulls. As there is association of tumor spread through foramen lacerum, there is a need for further studies, and large clinical studies based on imaging from various geographical regions.

1. .K DATTA Essentials of human anatomy, head and neck, 5^th edition chapter 1 page number 56
2. Christodouleas Hristov B, Lin SH, John P. Radiation oncology: A question-based review. Philadelphia, PA: Lippincott Williams & Wilkins; 2010. Page 138.
3. King AD, Vlantis AC, Bhatia KS, Zee BC, Woo JK, Tse GM, Chan AT, Ahuja AT. Primary nasopharyngeal carcinoma: diagnostic accuracy of MR imaging versus that of endoscopy and endoscopic biopsy. Radiology. 2011 Feb;258(2):531-7. doi: 10.1148/radiol.10101241. Epub 2010 Dec 3. PMID: 21131580.
4. Cao C, Yang P, Xu Y, Niu T, Hu Q, Chen X. Feasibility of Multiparametric Imaging With PET/MR in Nasopharyngeal Carcinoma: A Pilot Study. Oral Oncol (2019) 93:91–5. doi: 10.1016/j.oraloncology.2019.04.021 
5. Cao C, Xu Y, Huang S, Jiang F, Jin T, Jin Q, et al. Locoregional Extension Patterns of Nasopharyngeal Carcinoma Detected by FDG PET/MR. Front Oncol. 2021 Dec 13;11:763114. doi: 10.3389/fonc.2021.763114. PMID: 34966674; PMCID: PMC8710458.
6. Golub B, Bordoni B. Neuroanatomy, Pterygoid Plexus. 2023 Jul 24. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2025 Jan–. PMID: 32310356..
7. Chong VF, Fan YF, Khoo JB. Nasopharyngeal carcinoma with intracranial spread: CT and MR    J  Comput  Assist  Tomogr. 1996;20(4):563-69.
8. Wang WH, Lieber S, Mathias RN. The foramen lacerum: Surgical anatomy and
9. relevance for endoscopic endonasal approaches. J Neurosurg. 2018;131:01-12.
10. Tauber M,  van  Loveren  HR,  Jallo  G,  Romano  A,  Keller    The enigmatic foramen lacerum. Neurosurgery. 1999;44(2):386-91; discussion 391-93.
11. Sanghpriya Chaudhary, Suchit Kumar, Shivani Chaudhary , Shashi MunjalMorphometric Variations Of The Foramen Lacerum In Dry Skulls And Its Clinical Significance: A Cross-Sectional Study, International Journal Of Anatomy, Radiology And Surgery. 2023 Nov, Vol-12(6): Ao08-Ao10
12. Abd EL Naeem A. A morphologic and morphometric study of the foramen lacerum in adult human skulls: An osteological study in upper Egypt. Sohag Medical Journal. 2019;23(1):219-21. Doi: 10.21608/smj.2019.43707