Columna Cervical

Journal of Athletic Training 155

Journal of Athletic Training 2005;40(3):155–161

q by the National Athletic Trainers’ Association, Inc

www.journalofathletictraining.org

Cervical Spine Functional Anatomy and the

Biomechanics of Injury Due to Compressive

Loading

Erik E. Swartz*; R. T. Floyd†; Mike Cendoma‡

*University of New Hampshire, Durham, NH; †University of West Alabama, Livingston, AL; ‡Sports Medicine

Concepts, Inc, Geneseo, NY

Erik E. Swartz, PhD, ATC; R. T. Floyd, EdD, ATC; and Mike Cendoma, MS, ATC, contributed to conception and design and

drafting, critical revision, and final approval of the article.

Address correspondence to Erik E. Swartz, PhD, ATC, Department of Kinesiology, New Hampshire Hall, 124 Main Street,

University of New Hampshire, Durham, NH 03824. Address e-mail to eswartz@cisunix.unh.edu.

Objective: To provide a foundation of knowledge concerning

the functional anatomy, kinematic response, and mechanisms

involved in axial-compression cervical spine injury as they relate

to sport injury.

Data Sources: We conducted literature searches through the

Index Medicus, SPORT Discus, and PubMed databases and

the Library of Congress from 1975–2003 using the key phrases

cervical spine injury, biomechanics of cervical spine, football

spinal injuries, kinematics of the cervical spine, and axial load.

Data Synthesis: Research on normal kinematics and minor

and major injury mechanisms to the cervical spine reveals the

complex nature of movement in this segment. The movement

into a single plane is not the product of equal and summative

movement between and among all cervical vertebrae. Instead,

individual vertebrae may experience a reversal of motion while

traveling through a single plane of movement. Furthermore, vertebral

movement in 1 plane often requires contributed movement

in 1 or 2 other planes. Injury mechanisms are even more

complex. The reaction of the cervical spine to an axial-load impact

has been investigated using cadaver specimens and demonstrates

a buckling effect. Impact location and head orientation

affect the degree and level of resultant injury.

Conclusions/Recommendations: As with any joint of the

body, our understanding of the mechanisms of cervical spine

injury will ultimately serve to reduce their occurrence and increase

the likelihood of recognition and immediate care. However,

the cervical spine is unique in its normal kinematics compared

with joints of the extremities. Injury biomechanics in the

cervical spine are complex, and much can still be learned about

mechanisms of the cervical spine injury specific to sports.

Key Words: catastrophic injury, whiplash, injury mechanisms,

spinal cord, axial load

Because of the potentially catastrophic and life-altering

nature of cervical spine injury (CSI), much concern

exists regarding the prehospital management of the cervical

spine–injured athlete. This is evidenced by a multiprofessional

task force effort initiated by the National Athletic

Trainers’ Association to establish general guidelines for the

acute care of the spine-injured athlete.1 Major CSIs, although

rare compared with sprain and strain injuries to the extremities,

are troubling because of mortality rates and the potential permanent

loss of neural function. A CSI requires an immediate

and deliberate, yet sensitive, response. The highest rate of severe

neck injuries has occurred in American football and rugby.

2–8 Other sports and activities that contribute to a high rate

of CSI are wrestling, diving, recreational diving, ice hockey,

gymnastics, and horseback riding.3,5,9

The more severe CSIs associated with athletics can be attributed

to compressive forces from axial loading.10,11 Clinically,

a major CSI results in compromised integrity of the cervical

segment due to fracture, dislocation, subluxation, or

ligamentous tearing, leaving the cervical spine unstable. White

et al12 defined clinical instability in the spine as more than a

3.5-mm horizontal displacement of one cervical segment on

another. Obviously, the athletic trainer is unable to detect the

presence of such a diminutive irregularity in the structure of

the spine and must, therefore, assume the worst-case scenario.

Motion in one plane at the cervical spine requires the contribution

of complementary motion from individual vertebrae

in other planes.13–15 This further complicates the kinematics

of the cervical segment and the resultant injury mechanisms.

Considering the mechanism of injury is an important first step

for the on-field assessment of any athletic injury. An athlete

with a significant spinal cord injury may not immediately present

with emergent signs and symptoms. Therefore, understanding

the kinematics of the cervical spine is important for

the athletic trainer, not only in helping to appreciate the following

sections regarding injury mechanisms but also in allowing

for a more effective evaluative tool after CSI.

The purpose of this literature review is to provide a foundation

of knowledge concerning the functional anatomy, kinematic

response, and primary mechanisms involved in CSI

during participation in sports, specifically as they relate to axial-

compression forces. A secondary purpose of this review is

to demonstrate the need for research investigating sport injury

mechanisms of the cervical spine.

156 Volume 40 x Number 3 x September 2005

Figure 1. Posterior view of C1 (atlas) and C2 (axis).

Figure 2. The biconvex nature of C1 and C2. A, Translation. B,

Extension of C1 creating flexion in C2. C, Flexion of C1 creating

extension in C2.

FUNCTIONAL ANATOMY

The cervical spine’s range of motion is approximately 808

to 908 of flexion, 708 of extension, 208 to 458 of lateral flexion,

and up to 908 of rotation to both sides.16 However, movement

in the cervical spine is complex, because pure uniplanar movement

does not accurately portray the motion between cervical

levels, and movement into any range is not the simple sum of

equal motion from one vertebra to the next.13

Normal Kinematics of the Upper Cervical Spine

The

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