Muscle Strain: This is the most common cause of back and neck muscle spasms, often resulting from overuse, poor posture, or direct injury to the muscles.

Fibromyalgia: A chronic condition characterized by widespread muscle pain, fatigue, and tender points, which can include the back and neck.
Herniated Disc: A condition where the disc between the vertebrae bulges out, putting pressure on nerves and causing muscle spasms in the back and neck.
Degenerative Disc Disease: A condition where the spinal discs lose their cushioning ability, leading to pain and muscle spasms.
Spondylosis: A condition characterized by degenerative changes in the spine, including the discs, facet joints, and ligaments, leading to pain and muscle spasms.

Meningitis: An infection of the protective membranes covering the brain and spinal cord, which can cause severe neck stiffness and muscle spasms.
Spinal Cord Injury: Trauma to the spinal cord can cause muscle spasms, numbness, and paralysis.
Cauda Equina Syndrome: A condition where the nerves in the lower spine are compressed, leading to muscle spasms, numbness, and loss of bladder control.
Osteoporotic Compression Fracture: A fracture of the vertebrae due to osteoporosis, which can cause sudden back pain and muscle spasms.

Multiple Sclerosis: A chronic autoimmune disease that affects the central nervous system, causing muscle spasms, numbness, and vision problems.
Spinal Tumors: Abnormal cell growth in the spine, which can cause muscle spasms, numbness, and paralysis.
Inflammatory Myopathies: A group of chronic muscle diseases characterized by muscle inflammation and weakness, which can cause muscle spasms in the back and neck.
Tetanus: A bacterial infection that can cause muscle stiffness, spasms, and rigidity, including in the back and neck.