Again One More MRI Trivia Quiz

Explanation
The arrow labeled "a" points to the pedicle in the sagittal, T2-weighted MRI of the lumbar vertebra.

Explanation
The arrow pointing to D indicates the medial end of the rib. This can be determined by comparing the location of the arrow to the anatomy of the thoracic spine. The medial end of the rib is located closer to the midline of the body, which corresponds to the position of arrow D in the image.

Explanation
The supraspinous ligament is a strong ligament that runs along the posterior aspect of the vertebral column. It extends from the seventh cervical vertebra to the sacrum. In the cervical region, the supraspinous ligament continues as the ligamentum nuchae. The ligamentum nuchae is a thick, elastic ligament that runs from the external occipital protuberance to the spinous processes of the cervical vertebrae. It provides support and stability to the neck and helps maintain proper posture.

Explanation
In the given figure, arrow C points to the right subclavian artery.

Explanation
Arrow A points to the conus medullaris, which is the tapered end of the spinal cord. In the sagittal MR image of the lumbar spine, the conus medullaris can be identified as the lowest point where the spinal cord ends before it continues as a bundle of nerves called the cauda equina. The other arrows (B, C, and D) do not point to the conus medullaris but may indicate other structures or landmarks in the image.

Explanation
The correct answer is B. In the given figure, the arrow labeled B points to the thoracic pedicle. The pedicle is a bony structure that connects the vertebral body to the posterior elements of the spine. It can be identified in a CT scan as a small, round or oval-shaped structure located on either side of the vertebral body. In this case, arrow B is pointing to the correct location of the thoracic pedicle.

Explanation
The most posterior portion of the corpus callosum is called the splenium. The corpus callosum is a thick band of nerve fibers that connects the two hemispheres of the brain. It is divided into three main parts: the genu, the body, and the splenium. The genu is the anterior portion, the body is the middle portion, and the splenium is the posterior portion. Therefore, the correct answer is splenium.

Explanation
The arrow pointing to B indicates the clinoid process. The clinoid process is a bony projection located at the anterior aspect of the sella turcica, which is a saddle-shaped depression in the sphenoid bone. It serves as an attachment point for the tentorium cerebelli, a fold of dura mater that separates the cerebrum from the cerebellum. The clinoid process is important in providing stability and support to the brain and surrounding structures.

Explanation
The arrow labeled B points to the lamina in the axial CT of the thoracic vertebra.

Explanation
The tentorium cerebelli is a fold of dura mater in the brain that separates the cerebellum from the cerebral hemispheres. In the given figure, arrow D points to a structure that appears to be the tentorium cerebelli. The shape and position of this structure suggest that it is the tentorium cerebelli, as it is located between the cerebellum and the cerebral hemispheres, consistent with the anatomical location of the tentorium cerebelli.

Explanation
The anterior longitudinal ligament is a structure that runs along the anterior surface of the vertebral bodies in the spine. In the given figure, arrow C points to a structure that is located along the anterior surface of the vertebral bodies, indicating that it is the anterior longitudinal ligament.

Explanation
The spinous process is a bony projection that extends posteriorly from the vertebral arch. In the given figure, arrow D points to a bony projection that is consistent with the spinous process.

Explanation
The ethmoid sinuses are contained in the lateral masses of the ethmoid bone. The ethmoid bone is a small, delicate bone located between the eyes and forms part of the nasal cavity. It consists of several air-filled spaces called sinuses, and the lateral masses specifically house the ethmoid sinuses. These sinuses are responsible for producing mucus, filtering the air we breathe, and helping to lighten the weight of the skull.

Explanation
The spinous process is the posterior bony projection in the midline of each vertebra. In the given figure, arrow C points to the spinous process.

Explanation
The arrow pointing to C indicates the inferior endplate of L4 because it is the lowest arrow on the figure and is aligned with the L4 vertebra. The other arrows are pointing to different structures or are not aligned with the L4 vertebra.