Which spinal segment range is associated with a brachial plexus lesion in a cat or dog?

Which spinal segment range is associated with a brachial plexus lesion in a cat or dog?

• A. C1-C5
• B. C5-T2
• C. T3-L3
• D. L4-S2

Answer: (B)

The forelimb is supplied by the brachial plexus, which in dogs and cats is formed by the ventral rami of spinal nerves from C5 through T2. A lesion in this range disrupts the network that innervates the shoulder, elbow, carpus, and digits, causing forelimb weakness or paralysis and sensory loss in the corresponding limb. Lesions outside this range affect areas not limited to the forelimb—for example, cervical segments above C5 involve neck/upper regions, while thoracic segments below T2 involve the trunk or hindlimbs. Therefore, the range C5–T2 best matches the spinal roots that give rise to the brachial plexus and forelimb innervation.

The forelimb is supplied by the brachial plexus, which in dogs and cats is formed by the ventral rami of spinal nerves from C5 through T2. A lesion in this range disrupts the network that innervates the shoulder, elbow, carpus, and digits, causing forelimb weakness or paralysis and sensory loss in the corresponding limb. Lesions outside this range affect areas not limited to the forelimb—for example, cervical segments above C5 involve neck/upper regions, while thoracic segments below T2 involve the trunk or hindlimbs. Therefore, the range C5–T2 best matches the spinal roots that give rise to the brachial plexus and forelimb innervation.