The Spinal Extensors

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anatomy

By Greg Roskopf, MA

The Spinal Extensors
The Stabilizers of the Cervical Spine
his is the eighth in a series of articles that address how muscles work synergistically to create efficient movement at each joint. The previous article examined the muscles that support the thoracic spine; this discussion covers the posterior muscles of the cervical spine. The cervical spine’s muscle functions are more intricate and delicate than those of other spinal muscles. To decrease the potential for injury, be extremely conservative when using the joint range of motion (ROM) exam and suggested exercises. Under no circumstances should the movements or exercises be applied to any client with current injury or pain.

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muscles’ anatomy and study their function in cervical and capital motion. As with the muscles that extend the lumbar and thoracic spine, there is significant overlay between the muscles that extend the cervical spine and occiput. Such overlay makes it important to recognize the functional similarities between these muscles when you evaluate ROM or recommend exercises. Although integrated, the associated muscles have different functions relative to their insertions on the cervical spine or occiput. In general, the cervicis muscles regulate cervical extension; the capitis muscles regulate occipital extension.
1. The Splenius Capitis

A Kinesiological Look at the Cervical Spinal Extensors To understand the function of the muscles that stabilize the cervical spine and occiput, we must first look at the

This muscle runs superficially to the semispinalis capitis. With the splenius cervicis, it has an excellent lever arm for both cervical and capital extension. In addition, the splenius capitis both rotates and laterally bends the head to

THE CERVICAL SPINAL EXTENSORS: ORIGIN, INSERTION AND ACTION
Origin Splenius Capitis spinous processes of T3 through T1 and C7 through C4 spinous processes of T4 through T6 transverse processes of upper 4 to 7 thoracic vertebrae, articular processes of lower 5 cervical vertebrae transverse processes of all thoracic vertebrae (with semispinalis thoracis) transverse processes of upper 3 to 5 thoracic vertebrae and lower 3 cervical vertebrae transverse processes of upper 6 thoracic vertebrae upper borders of ribs 3 through 6 at angles articular processes of C7 through C4 Insertion mastoid process Primary Action cervical and capital extension cervical extension head and neck extension, cervical extension and lordosis

Splenius Cervicis Semispinalis Capitis

transverse processes of C1 and C2 between superior and inferior nuchal lines of skull

Semispinalis Cervicis Longissimus Capitis

cervical extension spinous processes of upper 6 thoracic and lower 4 cervical vertebrae and lordosis mastoid process extension of head, neck, cervical spine and occiput

Longissimus Cervicis Iliocostalis Cervicis Multifidus Cervicis

posterior tubercles of transverse processes of C2 through C5 transverse processes of C6 through C4 spinous processes of C5 through C2

cervical extension

cervical extension

cervical extension and stabilization, regulation of anterior shear of each segment cervical extension

Spinalis Cervicis

spinous processes of T2 through C6

spinous processes of C4 through C2

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JOINT RANGE OF MOTION (ROM) EXAM:
The following tests identify muscle weaknesses in the cervical and capital extensor muscles. For each test, instruct the client to perform the required movement while you check for asymmetrical motion. Isolating weak muscles in the cervical spine and occiput during the ROM exam can be complicated. Because the neck muscles intertwine, subtle changes in position can affect the muscles being emphasized. As with previous ROM exams that covered the spinal extensors, you will attempt to isolate groups of weak muscles rather than use a specific ROM test for each extensor muscle. The muscles are listed in order of emphasis with respect to the particular movement.

1. Prone, Extension of Cervical Spine, Maintaining Neutral Position of Occiput (No Capital Extension): Lying prone with head off the end of a
bench, client actively extends cervical spine while keeping chin neutral (no capital extension). Shoulders must remain flat, and motion must be achieved only through cervical spine. Limited motion represents weakness of splenius cervicis, splenius capitis, semispinalis cervicis, semispinalis capitis and longissimus cervicis.
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2. Prone, Extension and Rotation of Cervical Spine, Maintaining Neutral Position of Occiput (No Capital Extension): Lying prone with head
off end of bench, client actively extends and rotates cervical spine while keeping chin neutral (no capital extension). Shoulders must remain flat, and motion must be achieved only through cervical spine. Limited motion represents weakness of splenius cervicis, splenius capitis, semispinalis cervicis, semispinalis capitis, longissimus cervicis and iliocostalis cervicis.

3. Prone, Extension of Cervical Spine With Capital Extension: Lying prone with head off end of bench, client actively extends neck and head.
Shoulders must remain flat, and motion must be achieved only through cervical spine and occiput. Limited motion represents weakness of splenius capitis, semispinalis capitis and longissimus capitis.

4. Prone, Extension and Rotation of Cervical Spine With Capital Extension: Lying prone with head off end of bench, client actively extends
and rotates head. Shoulders must remain flat, and motion must be achieved only through cervical spine and occiput. Limited motion represents weakness of opposite-side semispinalis capitis and same-side semispinalis capitis and longissimus capitis.

CAUTION! If the client expresses apprehension or experiences pain in any position, do not perform the ROM test. Consider the associated muscles weak.

the same side when working unilaterally.
2. The Splenius Cervicis

This muscle runs superficially to the semispinalis cervicis. With the splenius capitis, it has an excellent lever arm for cervical spinal extension. The splenius cervicis also rotates and laterally bends the cervical spine to the same side when working unilaterally.
3. The Semispinalis Capitis

mechanical advantage for capital extension: The muscle’s attachments are placed well behind the axis, creating a long lever arm for extension. Working unilaterally, the semispinalis capitis rotates the head to the opposite side while laterally bending to the same side.
4. The Semispinalis Cervicis

creates a long lever arm for extension. Working unilaterally, the semispinalis cervicis creates rotation of the cervical spine to the opposite side while laterally bending to the same side.
5. The Longissimus Capitis

This large muscle runs up the cervical spine and deep to the splenius capitis. With the semispinalis cervicis, it has a major role in extending the cervical spine and maintaining cervical lordosis. Working bilaterally and with the cervical spine stabilized, it has a great

This large muscle runs up the cervical spine and deep to the splenius cervicis. With the semispinalis capitis, it also helps extend the cervical spine and maintain cervical lordosis. Through its attachment on the axis, the semispinalis cervicis stabilizes the axis, which provides an anchoring mechanism so the suboccipitals can function properly. The positioning of the attachments places the muscle well behind the axis and

This muscle runs deep to the splenius capitis and laterally to the semispinalis capitis and functions in extension of the cervical spine and occiput. It has a greater lever arm when functioning unilaterally to bend laterally and rotate the head to the same side.
6. The Longissimus Cervicis

This muscle runs deep to the splenius cervicis and laterally to the semispinalis cervicis and functions in extension of the cervical spine. Like the longissimus
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SUGGESTED EXERCISES
When recommending strengthening exercises for the extensor muscles of the cervical spine and occiput, consider each muscle’s role in head and neck motion. Because the extensor muscles work together to create stability through the cervical spine and occiput, these exercises focus on motion as opposed to the isolated strengthening of each muscle. Ideally, begin with isometric strengthening exercises for 2 to 3 weeks and follow up by implementing concentric-movement exercises; these exercises are designed to improve proprioception. The primary goal is to increase the muscles’ ability to contract through full range of motion (ROM). Work muscles into the predetermined range and emphasize all components of motion. To improve neurological input, emphasize control; for neurological reinforcement, use a precise number of repetitions. (The recommended numbers of sets and reps are noted with each exercise.) Be extremely cautious when working with muscles that support the cervical spine and occiput. To ensure a conservative approach, have the client perform each isometric exercise with 15 degrees less than extreme ROM to reduce the risk of cervical spine instability. Performing isometrics at 15 degrees less than total ROM also provides a 15-degree carryover in isometric strength, which helps stabilize the cervical spine as the client moves into extreme ROM for extension and rotation. Because extreme caution is required when you work the cervical spine and because the application of resistance is difficult (considering the motions involved), no weight-loaded exercises are described. Manual resistance applied by the trainer is most effective to strengthen the neck muscles through their ROM and will be described in both the concentric and the eccentric phases of the involved motion. Apply only light resistance and allow the client to move smoothly through ROM. You may modify the pressure, according to the client’s effort. CAUTION! If the client expresses apprehension or experiences pain when performing any of these exercises, stop immediately.

1. CERVICAL EXTENSION ISOMETRICS: Emphasizes splenius cervicis, splenius capitis, semispinalis cervicis, semispinalis capitis and longissimus cervicis. CAUTION! If client expresses apprehension or experiences pain when performing this exercise, stop immediately. Client Position
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actively extend cervical spine and occiput as trainer applies isometric resistance. Trainer Position
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Stand at side of table. Place stabilizing hand under client’s chin. Place action hand on client’s posterior skull. Same as in #1. Client performs 6 repetitions, holding each for 6 seconds.

Applied Resistance
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Lying prone with head off the end of a bench, actively extend cervical spine, keeping chin neutral (no capital extension) as trainer applies isometric resistance. Stand at side of table. Place stabilizing hand on client’s forehead. Place action hand on client’s posterior skull. Trainer applies isometric resistance. Client performs 6 repetitions, holding each for 6 seconds.

Trainer Position
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4. CAPITAL EXTENSION ISOMETRICS WITH ROTATION: Emphasizes opposite-side semispinalis capitis and same-side splenius capitis and longissimus capitis. CAUTION! If client expresses apprehension or experiences pain when performing this exercise, stop immediately. Client Position
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Applied Resistance
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2. CERVICAL EXTENSION ISOMETRICS WITH ROTATION: Emphasizes splenius cervicis, splenius capitis, semispinalis cervicis, semispinalis capitis, longissimus cervicis and iliocostalis cervicis. CAUTION! If client expresses apprehension or experiences pain when performing this exercise, stop immediately. Client Position
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Lying prone with head off end of bench, actively extend and rotate cervical spine and occiput as trainer applies isometric resistance. Same as in #3. Same as in #1. Client performs 6 repetitions, holding each for 6 seconds.

Trainer Position
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Applied Resistance
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Lying prone with head off end of bench, actively extend and rotate cervical spine, keeping chin neutral (no capital extension) as trainer applies isometric resistance. Same as in #1. Same as in #1. Client performs 6 repetitions, holding each for 6 seconds.

Trainer Position
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5. CERVICAL EXTENSION–MANUAL RESISTANCE: Emphasizes splenius cervicis, splenius capitis, semispinalis cervicis, semispinalis capitis and all cervical extensors. CAUTION! If client expresses apprehension or experiences pain when performing this exercise, stop immediately. Client Position
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Applied Resistance
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Lie prone with head off end of bench, cervical spine flexed and chin neutral. Same as in #1. Client actively extends cervical spine against trainer’s resistance, keeping occiput neutral. Do not allow capital motion; keep emphasis on extension of cervical spine.

3. CAPITAL EXTENSION ISOMETRICS: Emphasizes semispinalis capitis, splenius capitis and longissimus capitis. CAUTION! If client expresses apprehension or experiences pain when performing this exercise, stop immediately. Client Position
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Trainer Position
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Applied Resistance
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Lying prone with head off end of bench,

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Client returns cervical spine to flexed position, eccentrically resisting flexion applied by trainer. Client performs 2 sets of 12 repetitions.

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Lie prone with head off end of bench and cervical spine and occiput flexed. Same as in #3.

Trainer Position
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capitis, it has a greater lever arm when functioning unilaterally to bend laterally and rotate the cervical spine to the same side.
7. The Multifidus Cervicis

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Applied Resistance 6. CERVICAL EXTENSION WITH ROTATION–MANUAL RESISTANCE: Emphasizes opposite-side semispinalis cervicis and semispinalis capitis and sameside splenius cervicis, splenius capitis and longissimus cervicis. CAUTION! If client expresses apprehension or experiences pain when performing this exercise, stop immediately. Client Position
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Client actively extends cervical spine and occiput against trainer’s resistance, keeping occiput neutral. Client returns cervical spine to flexed position, eccentrically resisting flexion applied by trainer. Client performs 2 sets of 12 repetitions.

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These deep muscles of the erector spinae run obliquely from the upper thoracic and lower cervical transverse processes and two to four levels up the spinous processes to C2. The multifidus cervicis stabilizes the cervical spine and regulates the anterior shear of each segment.
8. The Iliocostalis Cervicis

Same as in #5. Same as in #1. Client actively extends and rotates cervical spine against trainer’s resistance, keeping occiput neutral. Client returns cervical spine to flexed position, eccentrically resisting flexion and counter rotation applied by trainer. Client performs 2 sets of 12 repetitions.

Trainer Position
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8. CAPITAL EXTENSION WITH ROTATION–MANUAL RESISTANCE: Emphasizes opposite-side semispinalis capitis and same-side splenius capitis and longissimus capitis. CAUTION! If client expresses apprehension or experiences pain when performing this exercise, stop immediately. Client Position
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Applied Resistance
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Lie prone with head off end of bench, cervical spine flexed and chin tucked. Same as in #3. Client actively extends and rotates cervical spine and occiput against trainer’s resistance. Client returns cervical spine to flexed position, eccentrically resisting flexion and counterrotation applied by trainer. Client performs 2 sets of 12 repetitions.

These deep muscles run laterally, originating from ribs 3 through 6 and running up and into the transverse processes of C4 through C6. Lateral to medial fiber alignment positions the iliocostalis cervicis to assist in cervical rotation to the same side.
9. The Spinalis Cervicis

Trainer Position
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Applied Resistance 7. CAPITIAL EXTENSION–MANUAL RESISTANCE: Emphasizes semispinalis capitis, splenius capitis and longissimus capitis. CAUTION! If client expresses apprehension or experiences pain when performing this exercise, stop immediately. Client Position
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These deep muscles of the erector spinae run vertically up the spinous processes from the upper thoracic vertebrae to C2. This muscle group has a poor mechanical position for movement and is noted more for segmental stability and proprioceptive feedback. Greg Roskopf, MA, is the owner of Muscle Activation Techniques (MAT), a biomechanics consulting company specializing in identifying and treating the causes of chronic and repetitive stress injuries. He teaches these concepts to trainers and therapists throughout the country and is a consultant to the Denver Broncos, Denver Nuggets and Utah Jazz. Contact him at (303) 745-4270 or visit his Web site at www.muscleactivation.com.