Structure M is the:

Structure M is the:

• A. Body of sphenoid (sphenoid sinus)
• B. Occipital bone
• C. Dorsum sellae
• D. Anterior clinoid process

Answer: (A)

This is about skull base anatomy and radiographic landmarks. The sphenoid sinus sits inside the body of the sphenoid bone, right along the midline of the skull base. On imaging you can see a midline, air-filled space surrounded by a thin bony shell—that’s the sphenoid sinus within the body of the sphenoid. The other structures mentioned lie in different places: the dorsum sellae is the back wall of the sella turcica, part of the saddle-shaped area that houses the pituitary; the anterior clinoid processes are bony projections near the optic canals; and the occipital bone forms the posterior part of the skull and the region of the foramen magnum. So Structure M is best identified as the body of the sphenoid containing the sphenoid sinus.

This is about skull base anatomy and radiographic landmarks. The sphenoid sinus sits inside the body of the sphenoid bone, right along the midline of the skull base. On imaging you can see a midline, air-filled space surrounded by a thin bony shell—that’s the sphenoid sinus within the body of the sphenoid. The other structures mentioned lie in different places: the dorsum sellae is the back wall of the sella turcica, part of the saddle-shaped area that houses the pituitary; the anterior clinoid processes are bony projections near the optic canals; and the occipital bone forms the posterior part of the skull and the region of the foramen magnum. So Structure M is best identified as the body of the sphenoid containing the sphenoid sinus.