Endoscopic vs Open Surgical Anatomy: Do We Teach the Wrong Landmarks?

For more than a century, surgical anatomy has been taught from open, external dissections: scalp reflected, neck flaps elevated, posterior muscles stripped off bone. Students learn relationships as they appear in a generous field under direct vision and handheld retraction. In contemporary practice, that is not how most surgeons operate.

Endoscopic sinus surgery, endonasal skull-base approaches, video-assisted thyroidectomy, transoral corridors and transforaminal spine procedures all rely on narrow working channels, oblique optics and magnified views. Yet many trainees still enter theatre with a mental map drawn from open exposure, orienting to landmarks they will not actually see and risk zones that shift once the camera goes in.^{1, 2}

Cadaveric dissection still usually proceeds from skin to bone in a straight line. That logic makes sense for classical neck exploration or wide craniotomies, and the descriptions in standard manuals reflect the same bias: the ethmoid roof is described as high and remote, the recurrent laryngeal nerve as reliably located in the tracheoesophageal groove and the vertebral artery as entering the transverse foramen at C6 in almost all cases.

Large pooled series show how incomplete this picture is. Meta-analysis of more than 28,000 recurrent laryngeal nerves found extralaryngeal branching in around 60% of nerves, with substantial side-to-side and study-type variation, directly challenging the idea of a single reliable groove trajectory.³ Work on non-recurrent nerves and laryngeal anastomoses further illustrates that the nerve is a plexiform, variable structure rather than a single predictable trunk.⁴

Sinonasal and anterior skull-base corridors

Endoscopic series examining ethmoid roof height and anterior skull-base slope using Keros, Gera or newer Thailand–Malaysia–Singapore (TMS) classifications make a simple point: a few millimetres of lateral lamella depth or a steeper skull-base angle can turn a seemingly safe ethmoid dissection into a high-risk manoeuvre.^{1, 2} From the endonasal corridor, the low lateral lamella and orbital wall become the first danger zones, not distant boundaries.

Frontal recess anatomy follows the same pattern. Cells such as agger nasi, suprabullar and frontal cells, which barely feature in older open-oriented descriptions, completely determine the endoscopic drainage pathway and the safe frontal sinusotomy corridor.

Spine corridors and Kambin’s triangle

Transforaminal lumbar approaches have their own version of this problem. Kambin’s triangle, and its later redefinition as Kambin’s prism, describe a three-dimensional safe corridor bounded by the exiting root, endplate and superior articular process. Cadaveric and imaging work shows major variability in this space across levels and patients — closely linked to the morphology of the vertebral canal, spinal cord and neural structures — meaning the working zone is safe only if the surgeon understands the endoscopic three-dimensional view.^{8, 9}

When trainees learn a region from open perspectives and then operate endoscopically, three predictable failure modes appear:

• False confidence: they can reproduce textbook diagrams but lose orientation once standard planes and long incisions disappear.
• Landmark misidentification: they look for a groove-based recurrent laryngeal nerve or a uniformly high skull base that simply does not exist in that patient.
• Slow, error-prone decision-making: they hesitate or compensate with excessive cautery, suction or force, especially in tight corridors such as the frontal recess or transforaminal window.

Educational studies on functional endoscopic sinus surgery show that structured endoscopic training improves performance, but only when the curriculum explicitly links what trainees see on the monitor to CT anatomy and to variant-aware risk schemes such as Keros, Gera or TMS — all tied to structures such as the nasal cavity, paranasal sinuses and anterior cranial base.^{5, 6}

Several teaching phrases are still repeated despite conflicting with pooled anatomical data or modern operative reality:

• “The recurrent laryngeal nerve lies in the tracheoesophageal groove.” Reliance on this assumption ignores the variability of the trachea–oesophagus interface and the branching behaviour of the laryngeal nerve.^{3, 4}
• “The ethmoid roof is uniformly high and slopes gently.” CT-based work routinely shows asymmetry in the ethmoid bone, deep olfactory fossae and steep anterior skull-base slopes.^{1, 2}
• “Kambin’s triangle is a universally safe zone.” Variability in neural and vascular structures surrounding the vertebral canal and sciatic nerve shows this space is not uniformly safe.^{8, 9}

These simplified statements become dangerous when transferred uncritically into endoscopic or fluoroscopic views.

Despite the growth of minimally invasive surgery, many curricula still treat endoscopic anatomy as a fellowship-level topic, to be learned after regional “basics”. Yet fundamental relationships — such as the position of the pituitary gland in endonasal skull-base surgery or the course of the thyroid gland relationships in video-assisted approaches — demand early exposure.^{5, 7}

Systematic reviews of endoscopic transsphenoidal training show a wide range of simulation methods built specifically around the endonasal corridor, reflecting that the endoscope is now central to neurosurgical and skull-base training.⁷

1. Approach-specific perspectives from the start

Every region should now be taught in both traditional open views and the operative corridor. Students must see how anterior, lateral and superior change when the camera enters the nasal cavity, the oral cavity or the foramina of the cranial nerves.

2. Landmarks tied to CT and three-dimensional imaging

Ethmoid roof height, frontal recess cells, optic canal protrusion, and vertebral artery entry levels should be taught with direct CT/MR correlation — linking to structures such as the paranasal sinuses, cranial base and cervical vertebrae.^{1, 9}

3. Simulation as core, not optional

Simulation shortens learning curves when feedback is structured around anatomy and variant recognition — especially for regions like the nasal cavity, sinuses and sphenoid.^{5, 6, 7}

4. Procedure-based anatomy blocks

Teaching should increasingly be organised around procedures — sinus corridors, transsphenoidal routes, transforaminal windows — mirroring real surgical thinking and linking each landmark to an operative purpose.

Open-surgery anatomy is not wrong, but it is no longer enough. As long as curricula prioritise wide, external views and treat endoscopic relationships as a postgraduate extra, trainees will continue entering theatre with a mental map that does not match the monitor.

Evidence from imaging, pooled nerve-variation studies and surgical education research all point in one direction: we need approach-specific, optics-matched, variant-aware anatomy teaching that starts early and uses simulation intelligently. Until that shift is made, the answer to the question in the title stays the same: yes, we are still teaching the wrong landmarks.