What is the nerve supply of the trapezius muscle?

From the Guidelines

The accessory nerve (CN XI) is the primary nerve supply of the trapezius muscle.

Nerve Supply Details

• The accessory nerve has a cranial root originating from the nucleus ambiguous within the medulla oblongata and a spinal root originating from the ventral horn of the spinal cord, between the C1 and C5 levels.
• The accessory nerve supplies portions of the sternocleidomastoid muscle and the upper portion of the trapezius muscle 1.
• Damage to the accessory nerve can result in weakness and atrophy of these muscles, causing decreased shoulder abduction, shoulder pain, cosmetic disfigureation, and disability.

From the Research

Nerve Supply of the Trapezius Muscle

The trapezius muscle receives its nerve supply from the following sources:

• Spinal accessory nerve (CNXI) [ 2, 3, 4, 5, 6 ]
• Cervical nerves (C3 and C4) [ 2, 3, 4, 5 ]

Motor Innervation

Studies have shown that the trapezius muscle receives motor innervation from:

• Spinal accessory nerve (CNXI) [ 2, 5, 6 ]
• Cervical nerves (C3 and C4) [ 2, 3, 4, 5 ]

Sensory Innervation

The trapezius muscle also receives sensory innervation from:

• Cervical nerves (C3 and C4) [ 5 ]
• Spinal accessory nerve (CNXI) [ 5 ]

Types of Innervation

Different types of innervation have been identified, including:

• Type I innervation: fibers derived from C-2 to C-4 [ 2 ]
• Type II innervation: fibers derived from C-2 to C-3 [ 2 ]
• Type III innervation: fibers derived from C-3 to C-4 [ 2 ]