In part two of this Blog, we will describe the structures that are commonly injured during a whiplash (hyper-extension hyper-flexion injury).
This next high-speed, forward motion, jerks the driver’s head back. In many cases the head moves right back over the headrest. This often occurs since most people keep their headrest too low to be effective, or it can occur due to poor head rest design. If the impact of the accident is severe enough, a considerable amount of soft-tissue and joint damage can occur in the front of the neck as the head is thrown back.
Common areas of damage as the head is thrown back:
o Facet joints are the most commonly injured joints in the neck.
§ These synovial facet joints support weight and control movement between each individual vertebrae.
§ The facet joints are the most common source of chronic pain neck pain after a whiplash injury.
American Academy Orthopedic Surgery 2007; 15:596-606).
Chronic cervical zygapophysial joint pain after whiplash: a placebo-controlled prevalence study. Spine 1996;21(15):1737-1745
o ALL (Anterior Longitudinal Ligament)
§ This ligament runs down the front of the vertebral bodies and prevents excessive extension. Damage to this ligament causes instability in the neck (cervical spine), and can be a cause of chronic neck pain after a whiplash injury. This occurs due to force being transmitted through the posterior spinal structures (facet joints).
Ivancic PC, Pearson AM, Panjabi MM, Ito S. Injury of the anterior longitudinal ligament during whipash simulation. European Spine Journal 2004;13:61-68.
Cholewicki J, Panjabi MM, Nibu K, Macius ME. Spinal ligament transducer based on a hall effect sensor. Journal of Biomechanics 1997;30(3):291-293.
o Facet capsules
§ The facet capsules in the neck are often injured due to the severity of muscle contractions and vertebra motions during whiplash accidents.
An anatomical investigation of the human cervical facet capsule, quantifying muscle insertion area J. Anat. (2001) 198, pp. 455–461
Anterior Muscles and Nerves Injured During Hyper-Extension
· This deep muscle runs along the front of your neck between the top vertebra in your neck (C1) and your mid-upper chest (T3) and is commonly injured in whiplash injuries.
· This muscle (Longus Colli) contains a high density of muscle spindle fibers. Muscles that contain a higher level of these fibers are used for fine motor control, muscle tone, and positional sense. Injuries to these muscles affect a broad range of motor functions.
Fiber composition and fiber transformations in neck muscles of patients with dysfunction of the cervical spine. Journal of Orthopaedic Research 1995;13:240-249
· This superficial muscle overlaps the SCM (sternocleidomastoid muscle). This muscle arises from the connective tissue (fascia) on the upper parts of the neck, chest (pectoralis major), and extends out over the shoulder (deltoid) and down over the collar bone (clavicle).
· The Platysma is supplied by the facial nerve (CN-VII). Injury to this muscle can create trigger points which cause a prickling type of feeling across the face and upper chest.
· These are a group of three muscles on the lateral side of the neck (anterior, medial, and posterior scalenes).
· A network of nerves (brachial plexus) and a major artery (subclavian artery) pass through the anterior and medial scalene muscles.
· This is an area that is commonly injured during whiplash accidents and can cause either neurological or vascular problems from the neck, right down to the hands.
o SCM (Sternocleidomastoid) muscle
· This superficial muscle is located on the lateral anterior side of the neck. It is involved in flexion and rotation of the neck
· Two major nerves (lesser occipital nerve and greater auricular nerve) pass by the SCM. Compression of these nerves generate symptoms of occipital neuralgia.
· Occipital neuralgia is a medical condition characterized by chronic pain in the upper neck, back of the head, and behind the eyes. This is sometimes known as C2 neuralgia or Arnold’s neuralgia.
· The Spinal Accessory Nerve provides input (motor innervations) to the SCM and Trapezius muscles. Compression of this nerve can result in limited range-of-motion and decreased strength of the SCM and Trapezius muscles. This will affect shoulder and neck strength.
See Part 3 – Resolving Whiplash Injuries with Active Release for a continuation of the biomechanics of a whiplash accident and a review of commonly injured structures.
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