The muscles of the neck play an important role in human physiology. The neck has several muscles that help support the head and others that facilitate speaking and swallowing. Some of these muscles are innervated by cranial nerves, whereas others receive their nerve supply from spinal nerves. Weakness and atrophy of neck muscles threaten survival; an inability to support the head can cause life-threatening injuries to the spinal cord.
Cervical plexus: a network of nerves formed by the anterior rami (branches) of the first four cervical spinal nerves (C1-C4). This plexus is located in the neck, deep to the sternocleidomastoid muscle.
Cervical vertebrae: seven vertebrae (C1 to C7) located in the neck region of the vertebral column (spine).
Cranial nerve: a nerve that emerges directly from the brain stem, as opposed to from the spinal cord.
Extension of the head: tilting the head back, as if to look up at the sky.
Innervated: to be supplied with nerves. A muscle must be innervated in order to receive signals from the brain.
Spinal nerve: a nerve that emerges from the spinal cord.
Suboccipital: the area beneath the occipital bone of the skull, at the base of the skull and upper part of the neck.
Thoracic vertebrae: twelve vertebrae in the middle segment of the vertebral column (spine), located between the cervical (neck) and lumbar (lower back) regions.
The following muscles in the neck support the head:
Neck muscles involved in supporting the head will weaken in the same manner as any other muscle affected by ALS; once the disease has set in to a given nerve, the muscles innervated by that nerve will begin to weaken.
The pattern of neck weakness progression as it pertains to supporting the head varies from individual to individual, however, “drop head”, where the head tends to drop forward is the most common early sign of neck weakness.
Bracing becomes necessary to ensure safety and comfort when neck muscles can no longer adequately support the head. Proper head and neck support is crucial to prevent injury, especially during transfers. Adequate head support is also important while riding in a vehicle to prevent the head from striking parts of the interior, particularly during sudden movements or large bumps that can cause the head to move beyond the control of weakened neck muscles.
See: Occupational Therapy: Head and Neck Support