The cervical spine consists of seven vertebrae that provide mobility but less stability than other regions of the spine. It has three subsystems that contribute to stability - passive (bones and ligaments), active (muscles), and neural control. Cervical instability occurs when the neutral zone between ranges of motion increases, the stabilizing subsystems can no longer compensate, and motion quality becomes poor. It can result from trauma, surgery, disease, or degeneration and often involves pain.

1. Background Knowledge:
Functional Anatomy of Cervical Spine:
The cervical spine is made up of the first seven vertebrae in the
spine. It consist of several pairs of joints. It is an area where
stability has been sacrificed for mobility. The seven vertebrae
of the cervical spine can be divided into two groups. The
upper (Occiput-C1 and C2) and the lower (C2-C7) cervical
spine according to structure and function. The transverse
processes of cervical vertebraes are reduced to allow better
mobility, and there is a foramen to allow passage to the
vertebral artery. The lateral portions of the vertebral bodies
form the joints of Luschka, which also facilitate mobility of the
lower cervical spine. The facet joints of the lower cervical
spine are in the sagittal plane and incline forward at
approximately 45° to allows the facet joints to bear weight and
guides the motion of the segment. The bony structure of the
upper cervical spine (occiput- C1-C2) is specialized to allow a
great deal of mobility and to protect the medulla oblongata The
joint surfaces of the superior facet of C2 are aligned in the horizontal plane to allow
approximately 90° rotation. There is no intervertebral disk between the C1 and C2 because the
atlas, with concave joint surfaces above and below, serves the function of the disk. The resting
and closed packed position of cervical spine is slight Extension and full extension respectively
with capsular pattern, slight flexion and rotation equally limited than extension.
The cervical vertebra are small and can be distinguished from other vertebrae of spine by having
following characteristics except the first, second, and seventh which present some exceptional
features. Each vertebra has got a body which is small and broader from side to side than from
before backward having pedicles directed laterally and backward and laminae which is narrow
and thin. The vertebral foramen is large, and of a triangular form. The spinous process is
short and bifid. The superior and inferior articular processes on either side are fused to form an
articular pillar, which projects laterally from the junction of the pedicle and lamina. The
transverse processes are each pierced by the foramen transversarium, which, in the upper six
vertebrae gives passage to the vertebral artery and vein and a plexus of sympathetic nerves.
The First Cervical Vertebra:
The first cervical vertebrae is named the atlas because it supports
the globe of the head. It look like a ring having no body and
spinous process and consists of an anterior and a posterior arch
and two lateral masses. The lateral masses are the most bulky
and solid parts of the atlas, in order to support the weight of the
head. Each carries two articular facets, a superior and an
inferior. The superior facets are of large size, forming a cup for

2. the condyle of the occipital bone, and are modified for the nodding movements of the head.
The inferior articular facets articulates with the axis permitting the rotatory movements of the
head. The transverse processes are large, project lateraly and downward from the lateral
masses, and serve for the attachment of muscles which assist in rotating the head. The foramen
transversarium is directed from below, upward and backward.
The Second Cervical Vertebra:
The second cervical vertebra is named the epistropheus or axis
because it forms the pivot upon which the first vertebra,
carrying the head, rotates. The most distinctive characteristic
of this bone is the strong odontoid process. The lamina is
thick and strong, and the vertebral foramens are large. The
transverse processes are very small, perforated by the foramen
transversarium. The spinous process is large and strong.
The Seventh Cervical Vertebra:
The most distinguishing characteristic of this vertebra is the
existence of a long and prominent spinous process, hence
named as vertebra prominens. The transverse processes are of
considerable size.
Joints and Ligaments:
The anterior and posterior longitudinal ligaments and the
ligamentum flavum are present in the cervical spine from C2
through C7. The interspinous and supraspinous ligaments blend
with the nuchal ligament of the cervical spine. The nuchal
ligament has its origins on the spinousprocesses of the cervical
spine and is inserted on the occiput. Its function is to prevent
hyperflexion of the neck. The posterior longitudinal ligament
ends at C2. The transverse ligament of the atlas has its origin
and insertion on the interior surface of the anterior ring of the
atlas. The alar ligament is a winglike structure that has its origin
on the lateral borders of the dens and its insertion on the occiput.
It is a main contributor to the stabilization system of the upper
cervical spine. The apical ligament has its origin on the tip of
the dens and inserts on the occiput. It becomes taut when
traction is applied to the head. The joint capsule of the atlanto-

3. occipital joint is reinforced with ligaments. The lateral placement of the atlanto-occipitaljoint
capsules and ligaments severely limits rotation of the occiput on the atlas.
Primary Ligaments Include:
Ligament Spinal Region Limits
Alar Axis – skull Head rotation & lateral flexion
Anterior Atlantoaxial Axis & Atlas Extension
Posterior Atlantoaxial Axis & Atlas Flexion
Ligamentum Nuchae Cervical Flexion
Anterior Longitudinal Axis – Sacrum Extension & reinforces front of annulus fibrosis
Posterior Longitudinal Axis – Sacrum Flexion & reinforces back of annulus fibrosis
Ligamentum Flavum Axis – Sacrum Flexion
Reference:http://www. spineuniverse. com/anatomy/ligaments
Muscles of the cervical Spine Column:
Cervical muscles Function Nerve
Sternocleidomastoid Extends & rotates head, flexes vertebral
column
C2, C3
Scalenus Flexes & rotates neck Lower cervical
Spinalis Cervicis Extends & rotates head
Middle/lower
cervical
Spinalis Capitus Extends & rotates head
Middle/lower
cervical
Semispinalis Cervicis Extends & rotates vertebral column
Middle/lower
cervical
Semispinalis Capitus Rotates head & pulls backward C1 – C5
Splenius Cervicis Extends vertebral column
Middle/lower
cervical
Longus Colli Cervicis Flexes cervical vertebrae C2 – C7
Longus Capitus Flexes head C1 – C3
Rectus Capitus Anterior Flexes head C2, C3
Rectus Capitus Lateralis Bends head laterally C2, C3

4. Iliocostalis Cervicis Extends cervical vertebrae
Middle/lower
cervical
Longissimus Cervicis Extends cervical vertebrae
Middle/lower
cervical
Longissimus Capitus Rotates head & pulls backward
Middle/lower
cervical
Rectus Capitus Posterior
Major
Extends & rotates head Suboccipital
Rectus Capitus Posterior
Minor
Extends head Suboccipital
Obliquus Capitus Inferior Rotates atlas Suboccipital
Obliquus Capitus Superior Extends & bends head laterally Suboccipital

5. CervicalInstability:
Spinal instability is defined as the inability of the spine to
maintain correct vertebral alignment due to either of bony
changes or of neuromuscular pathology. Cervical
instability can occur secondary to trauma, surgery,
systemic disease, or tumors. However, most patients
diagnosed with cervical instability suffer from
degenerative changes to the motion segment. Stability
is necessary for proper functioning of the kinematics of
the spine.
Structural and Functional Components of Cervical
Instability:
Many authors have identified and described the common components of spinal stability into 3
functionally integrated subsystems (passive, active and neural control) of the spinal stabilizing
system.
The passive subsystem consists of the vertebral bodies, facet joints and capsules, spinal
ligaments and passive tension from spinal muscles and tendons. This subsystem provides
significant stabilization of the elastic zone and limits the size of the neutral zone. The
components of the passive subsystem act as transducers and provide the neural control
subsystem with information about vertebral position and motion as well.
The active subsystem, which consists of spinal muscles and tendons, generates the forces
required to stabilize the spine in response to changing loads. It is primarily responsible for
controlling the motion occurring within the neutral zone and contributes to maintaining the size
of the neutral zone. The spinal muscles also act as transducers, providing the neural control
subsystem with information about the forces generated by each muscle.
The neural control subsystem receives information through peripheral nerves and the central
nervous system, from the transducers of the passive and active subsystems about vertebral
position, vertebral motion, and forces generated by spinal muscles. The neural control
subsystem then determines the requirements for spinal stability and acts on the spinal muscles to
produce the required forces.
Clinical instability of the spine occurs when the neutral zone increases relative to the total range
of motion, the stabilizing subsystems are unable to compensate for this increase, and the quality
of motion in the neutral zone becomes poor and uncontrolled. Degeneration and mechanical
injury of the spinal stabilization components are the primary causes of increases in neutral zone
size. The factors contributing to the degeneration or mechanical injury are poor posture,
repetitive occupational trauma, acute trauma and weakness of the cervical musculature. Since
poor quality of motion is a major aspect of clinical instability, aberrant motions during active

6. movements occurring in the mid-ranges of active cervical movement are cardinal signs of
clinical cervical instability.
Cervical spine pain is a common musculoskeletal condition reportedly affecting 70% of people
within their life time. Instability is one element of cervical pain and may contribute to the
clinical presentation of various conditions, including cervicogenic headaches, chronic whiplash
dysfunction, rheumatoid arthritis, osteoarthritis, and segmental degeneration. Situations
involving trauma, genetic predisposition, disc degeneration, and surgery may compromise the
stabilizing mechanisms of the cervical spine (Cook et al 2005).
There is a wide spectrum of conditions that come under the term ‘instability’ some of which can
be serious and life threatening such as instability of the transverse ligament associated with
rheumatoid arthritis, an inflammatory cause or downs syndrome, a congenital cause (Swinkles et
al 1996). Kesson and Atkins (2005) describe the possibility of drop attacks being produced by
more severe instability of the upper cervical segment which may be due to congenital
ligamentous laxity of the atlantooccipital joint, deformed odontoid cervical spondylosis or
spondylolysthesis. According to Swinkles at al (1996) post whiplash patients with a minor non
life threatening instability that results in persistent pain would be the other end of this spectrum.
Instability is described by Maitland as an abnormal movement of intervertebral joints that has
laxity of supportive ligaments making it unstable. Maitland also refers to hypermobility in the
spine as one or more intervertebral joints that are excessively mobile in relation to the
neighbouring joints.
According to Darlen Hertling and Randolph M. Kessler Passive stability of the cervical spine
depends upon the tripod configuration of the two posterior facet joints and the anterior disk.
When the cervical spine is in its normal resting position of few degrees of lordosis, the facet
joints are mainly responsible to bear the vertical compressive forces. There is minimal activity
of the muscle is required in this position. This Passive phenomenon of stability may be lost as a
result of an injury eg, acceleration Injury, bad posture or activities that frequently involve flexion
of the neck. If cervical lordosis is lost, the facet joint loses this phenomenon of stabilization
and the vertical compressive forces are shifted forward onto the disk, which gradually stretches
out and weakens the annulus of the disk. The vertebral bodies in turn may show lipping and
traction spurs as an attempt to compensate for increased vertical compressive forces. This
weakening of the disk’s annulus may lead to bulging of nuclear material.
Instability was defined by Schmorl and Junghans in 1971 as "A loosening of the motion
segment" They regarded this pathologicay the most common reason for the poor performance of
two vertebrae and their associated tissues.
Farfan and Gracovetsky I, considering biomechanical principles stated instability “a
symptomatic condition where in the absence of new injury, only physiological load brings
abnormally large deformations in the intervertebral joint".
Radiographically appreciable cervical spine instability (RACSI) leading to compression of neural
or vascular structures, pain, and neurological signs and symptoms reveals marked disruption of

7. passive osseo ligamentous anatomical limitations and hypermobility. Dysfunction of the active
and neural subsystems is more appropriately described as an abnormality of movement rather
than hypermobility and has been referred to as clinical cervical spine instability (CCSI). It may
demonstrate only subtle symptoms and clinical examination features and radiographic findings
are frequently normal (Cook et al 2005). The upper cervical spine differs functionally and
anatomically to the rest of the cervical spine and these differences causes the atlantoaxial joint to
be more prone to subluxation. The bony structure facilitates mobility rather than stability.
55% of cervical rotation taking place at the atlanto axial joint. The upper cervical spine
ligaments (transverse ligament, alar ligaments and tectorial membrane) have an essential
stabilising role (Swinkles et al 1996. ) Total range of motion (ROM) in the spine can be divided
into two components, the neutral zone (NZ) and the elastic zone (EZ). Initially, minimal
resistance to motion is encountered as the spine moves through the NZ, after this continuing
movement is accompanied by higher levels of resistance, as the spine moves within its EZ.
Spinal instability is associated with an increase in the neutral zone (NZ) of the spine. The fact
that spinal fusion, an extreme treatment for instability has been shown to remove pain in patients
with whiplash injury suggests that instability and pain are strongly related (Klein et al 2001).
Signs and Symptoms of cervical instability:
o A history of major trauma
o Apprehension when moving neck into extension or difficulty returning from extension
o Sharp pain with sudden movements
o Neck crepitus, catching, clicking, clunking or popping sensations.
o Locking or giving way
o occipital and frontal or retro-orbital headaches
o paraspinal muscle spasm
o decreased cervical lordosis,
o Feeling of a lump in the throat
o Aberrant movement.
o Poor muscular control
o Shoulder girdle weakness/atrophy
o Feeling of ‘heavy head’, or ‘head is dropping off’
o Intolerance to prolonged static postures
o Better with external support (hands or collar)
o Frequent need for self-manipulation,
o Signs of hypermobility on X-ray
o Excessively free end-feel on passive motion testing
o Young females with long thin necks.
The Clinical Findings / Signs considered important are:
o Hyperreflexia
o Paraesthesia
o Coordination problems/Ataxia
o Spasticity or pareses

8. o Hypoesthesia in the area of the occipitalis major nerve ( less frequent)
o hypoaesthesia of both hands and/or feet
o Pain in the upper cervical or suboccipital areas (70%)
o Variable radiation to mastoid, occipital, temporal, or frontal regions
o Limitation of neck movement
o Torticolli
o tinnitus
o diplopia
o dizziness
o dysarthria
o dysphagia
o feeling of the head 'falling off' when going over a bump in a car
o limb muscle wasting and weakness
o nausea or vomitting
o altered sphincter control
o paraesthesia of lips
o retro-occular pain
o spasticity (cord like symptoms)
Physical findings may include positive stability testing, hyper-reflexia in the limbs, babinski,
clonus, weakness, loss of balance, loss of active movement due to severe muscle spasms,
excessive movement'drop attacks' or other unusual neurological symptoms.
Clinical testing for upper cervical spine instability:
Test Description Positive Test
Sharp- Pursor Test
 The palm of one hand
is placed on the
patient’s forehead and
with the other hand the
spinous process of the
axis is then gently
fixed by a pinch grip.
 The head and neck are
gently flexed to 20
degrees.
 With pressure applied
on the forehead, the
occiput and atlas are
translated posteriorly.
Reduction in symptoms with
and/or no sliding or
“clunking” noted with PA
movement.
Alar Ligament Stress Test
 Patient is supine and
the therapist grips and
stabilizes the spinous
With passive movement of the
head there is a lag or delay of
C2 spinous process movement

9. process of the axis.
 The head and atlas are
then side bent around
the coronal axis of the
atlantoaxial joint.
 Ipsilateral rotation of
the axis is prevented
by the stabilization of
the axis.
 The end feel and the
amount of motion are
assessed. If the alar
ligament is intact, little
to no side bending can
occur and the end feel
should be capsular.
 The test is then
repeated with rotation
of the head and atlas
on the axis and the end
feel is assessed.
Anterior Shear Test
( Transverse Ligament Test)
 Patient is supine and
the therapist supports
the occiput in the
palms of the hands and
the third, fourth, and
fifth fingers while the
2 index fingers are
placed in the space
between the occiput
and the C2 spinous
process, thus overlying
the neural arch of the
atlas.
 The head and C1 are
then lifted (sheared)
anteriorly together,
while the head is
maintained in its
neutral position and
gravity fixes the rest of
the neck.
Sensation of lump in the throat
or the presence of cardinal
signs.

10. Management of Upper Cervical Spine
Instability:
The most effective and Integral component of Management
of Upper cervical spine Instability is to restore the normal
lordosis followed by postural correction to unload the
hypermobile segment. This should be accomplished by
carefully mobilizing any restriction of upper and mid
cervical spine to restore ROM. Lordosis is a dynamic
position and can not be restored passively. Strengthening
of the Multifidi is the best way to re-establish cervical
lordosis and stability. Segmental strengthening of the cervical spine should be followed by
restoration of muscular balance of the cervical spine. Strengthening of longus colli and longus
capitis muscle is very important. Strengthening of short neck flexors using head nod exercise
should be started as early as possible and this should be followed by co-contration of cervical
extensors. Care must be taken in exercise instruction to avoid strengthening of Sterno-cleido
mastoid muscle. Vigorous rotator mobilization or passive stretching should be avoided because
this may overstretch the segments that are already hypermobile. The resting position of
shoulder girdle plays an integral role in conveying the translational forces to the cervical spine
therefore exercises should be developed to correct the impairments found on assessment of the
shoulder girdle. Care must be taken throughout this program to control motion at the
hypermobile segment especially for excessive translation because of large neutral zone of
cervical spine. Much of the stability in this region is provided by dynamic control of the active
muscular system. Specialized muscular training and ergonomics instruction are important part
of the exercise regimen even in the absence of hypermobility of the motion segment.