Sensory Exam
Anatomy of the Sensory System
- You will get the anatomy in detail from Dr Scott so I will review it only to highlight clinically relevant points
- The 2 main sensory pathways, the posterior columns/medial lemnicus system (PC/ML)and the anterolateral system (ALS), each contain 3 neurons
- The ALS crosses over in the spinal cord whereas the PC/ML crosses over in the medulla
- This means that a patient with a spinal cord lesion could have loss of pain and temperature on one side and loss of position sense and vibration on the other side
Anterolateral System
- The 1st order neurons enter the spinal cord and may ascend in Lissauer’s tract (see red square) for 2-3 segments before synapsing in the dorsal horn or the second order neurons may take 2-3 segments as they move in the anterior commissure (see green square)before crossing over into the white matter of the anterolateral pathway on the contralateral side
![iDevice icon](icon_reflection.gif)
What is the clinical importance of this fact?
![iDevice icon](icon_reflection.gif)
If the first order neurons of the anterolateral system are impaired, what other system would you want to ask the patient about?