Question

The correct order of channelisation of neural information down the upper limb is represented by (from proximal to distal):
A. \( C_5 \) to \( T_1 \) nerve roots
B. Radial nerve
C. Posterior cord of brachial plexus
D. Superior, Middle and Inferior trunk of Brachial plexus
Choose the correct answer from the options given below:

• A. D, A, B, C
• B. A, D, C, B
• C. A, C, D, B
• D. A, D, C, B

Hint:

Remember: Roots → Trunks → Divisions → Cords → Branches (RTDCB) Radial nerve comes at the end as a terminal branch.

Answer 1

The Correct Option is B

Concept:
The brachial plexus follows a well-defined anatomical sequence for transmission of neural signals from the spinal cord to the peripheral nerves of the upper limb. The order is: \[ \text{Roots} \rightarrow \text{Trunks} \rightarrow \text{Divisions} \rightarrow \text{Cords} \rightarrow \text{Branches} \]

Step 1: Identify the starting point (Roots).
The nerve roots involved in the upper limb are: \[ C_5, C_6, C_7, C_8, T_1 \] Thus, the most proximal structure is: \[ A: C_5 \text{ to } T_1 \text{ nerve roots} \]

Step 2: Formation of Trunks.
The roots combine to form trunks:
• Upper (C5–C6)
• Middle (C7)
• Lower (C8–T1) Thus, next in sequence: \[ D: Trunks \]

Step 3: Formation of Cords.
After trunks divide, they recombine into cords:
• Lateral cord
• Medial cord
• Posterior cord Thus: \[ C: Posterior cord \]

Step 4: Terminal Branches.
Finally, cords give rise to peripheral nerves such as:
• Radial nerve
• Median nerve
• Ulnar nerve Thus: \[ B: Radial nerve \]

Step 5: Final Order.
\[ A \rightarrow D \rightarrow C \rightarrow B \] \[ \boxed{\text{Correct answer = Option (2)}} \]