Chapter 10

Trunk and Spinal Column

Section 10 - Trunk & Spinal Column

Learning Outcomes: Students will be able to:

  1. Describe the musculoskeletal anatomy of the spinal column, trunk, ribcage and associated connective tissues that support these joints.
  2. Articulate the functional design of the atlantooccipital and intervertebral joints and the osteokinematic and arthrokinematic movements possible at the joints.
  3. Describe the origin, insertion, actions, and nerve innervation of select muscles that act on the lumbar, thoracic, and cervical joints.
  4. Identify how to strengthen and stretch each of the muscles or muscle groups that act upon the segments of the spinal column.
  5. Articulate the mechanisms that can contribute to pathology of intervertebral joints and discs, and the proper techniques to reduce the risk while enhancing performance.
  6. Identify spinal and lower extremity pathologies related to vertebral disc and other spinal pathology using knowledge of myotomes, dermatomes, and cutaneous distribution patterns.
  7. Identify the causative factors that contribute to the development of lordosis/lower crossed syndrome and scoliosis, how to assess for their presence and be able to implement interventions to address these conditions

The spine, also known as the spinal or vertebral column, is a column of individual vertebrae stacked one on top another. The spine has four major functions:

  1. Provide structural support for the body (support for head and transmittal of weight to the pelvis)
  2. Allow for movement (the summation of 25 spinal segments together allow significant movement)
  3. Protect the spinal cord (bony protection)
  4. Provide shock absorption for the body (nucleus pulposus of intervertebral disc and spinal curves)

Figure 1

Regions of the Spine

Cervical Spine (neck) contains seven vertebrae (C1-C7) with the convexity of the curve anterior (lordosis).

Thoracic Spine (upper and middle back) contains twelve vertebrae (T1-T12) with the convexity of the curve posterior (kyphosis).

Lumbar Spine (low back) contains five vertebrae (L1-L5) with the convexity of the curve anterior (lordosis).

Sacrococcygeal spine (pelvic) contains the sacrum consisting of five fused vertebrae (S1-S5) and the coccyx consisting of four partially or fully fused vertebrae (Co1-Co4) with the convexity of the curve posterior (kyphosis).

Development of Spinal Curves

Primary Curves (thoracic and sacrococcygeal) are formed before birth.

Secondary Curves (cervical and lumbar) are formed after birth.

Note: The terms of kyphosis and lordosis are sometimes used to describe excessive curvatures in the thoracic and lumbar spinal regions respectively. However, they are also used to simply describe the direction of the curves with the cervical and lumbar regions projecting anteriorly (lordosis – a position of extension), and the thoracic and sacrococcygeal regions projecting posteriorly (kyphosis – a position of flexion).

Atlantooccipital & Atlantoaxial Joints

Atlantooccipital (condyloidal)

- Occiptial condyles of skull sitting on the articular fossa of the atlas. ≈15° flexion/extension from anatomical.

Atlantoaxial composed of two lateral facet joints (arthrodial) and one median joint named atlanto-odontoid (trochoidal).

Rotation of atlas (C1) around the fingerlike process (odontoid process or dens) of the axis (C2) during rotation of the head.

  • 40° rotation (right and left from anatomical).


Figure 2

Joints of the Spine

Spinal joints involve two adjacent vertebrae which is known as a spinal segment. Each spinal segment is made up of an anterior median joint (intervertebral disc joint) and two posterolateral joints (vertebral facet joints). Naming a spinal segment is done by referencing the levels of the two vertebrae involved. For example, the joint between the third thoracic vertebrae and the fourth thoracic vertebrae is called the T3-T4 spinal segment.

Vertebral Facet Joints: the articulation between the inferior articular process/facet of the superior vertebra and the superior articular process/facet of the inferior vertebra. The orientation (plane of joint) of the facets determine the movement that is best allowed at that level of the spine. From C1-C2 to L5-S1,the facet joints are arthrodial joints.

Cervical facets: oriented in an oblique plane (45º between the transverse and frontal planes) allowing motion in the transverse plane (neck right and left rotation) and frontal plane (neck right and left lateral flexion).

Thoracic facets: generally oriented in a frontal plane facilitating trunk right and left lateral flexion (limited by rib cage).

Lumbar facets: generally oriented in the sagittal plane mostly allowing lumbar flexion and extension.

Figure 3

Spinal Movements & Range of Motion

Cervical Region: Flexion 50-60°, Extension 50-60°, Right and Left Lateral Flexion 45°, Rotation 80°

Thoracic Region: Flexion 35º, Extension 25º, Right and Left Lateral Flexion 25º, Right and Left Rotation 30º

Lumbar Region: Flexion 30°, Extension 20°, Right and Left Lateral Flexion 20°-30º, Right and Left

Rotation 5°

Vertebral Facets & Spinal Motion

Spinal Flexion: Both facets “open”

Spinal Extension: Both facets “close”

Side Bending and Rotation: Concavity side “closes” and convexity side “opens”.

Figure 4

Intervertebral Disc Joint: is located between the bodies of two adjacent vertebrae and classified as an amphiarthrodial – symphysis joint. The disc is composed of 1) an outer annulus fibrosus and  2) an inner nucleus pulposus. The disc is attached to the bodies of the vertebrae via the vertebral endplates. The disc allows for movement, absorbs shock, helps bear the weight of the body, and helps maintain the opening of the intervertebral foramina.

  1. Annulus Fibrosus: a tough fibrosus ring shaped fibrocartilaginous material that encircles and encloses the nucleus pulposus. Contains multiple rings in a basket weave configuration (each successive layer with a different fiber orientation) giving it the ability to resist distraction forces, shear forces, and torsion forces.

  1. Nucleus Pulposus: a gel type material (at least 80% water) located in the center of the annulus fibrosus providing shock absorption properties to the spine.

  1. Vertebral Endplate: composed of hyaline articular cartilage and fibrocartilage, it lines the articulating surfaces of each vertebral body.

Figure 5

How to Keep Intervertebral Discs Healthy

-Exercise Regularly              -Avoid Smoking      

-Drink Plenty of Water         -Avoid Alcohol                                                                                                                    

-Eat a healthy diet                 -Avoid Repetitive

                                                  Flex/Ext Exercises    

Myotome & Dermatome Testing

As previously mentioned, spinal nerves have motor fibers and sensory fibers. The motor fibers innervate certain muscles, while the sensory fibers innervate certain areas of skin.

Nerve Damage: Nerves are typically injured through compression or tensile/stretching forces. When a nerve root in the brachial or lumbosacral plexus is damaged, certain patterns of motor and sensory deficits occur in the corresponding limbs. Myotomes and dermatomes are used to evaluate these deficits.

Myotome Testing

The myotomes may be tested, in the form of isometric resisted muscle testing, for weakness of a particular group of muscles. Results may indicate lesion to the spinal cord nerve root level, or intervertebral disc herniation pressing on the spinal nerve roots. All tests should be compared bilaterally.

**Link to view myotome testing procedures: (

Lower Extremity Myotomes

Nerve Root Level

Patient Position

Joint & Movement Resisted (tested)



Hip flexion



Knee extension


Long sit

Ankle dorsiflexion


Long sit

Big toe extension



Ankle plantarflexion, Foot eversion, and Hip extension



Knee flexion

Dermatome Testing

To test for sensory nerve root damage, the corresponding dermatomes supplied by that nerve root may be tested for abnormal sensation (Hypoesthesia = decreased sensation, Hyperesthesia = excessive sensation, Anesthesia = artificially induced loss of pain sensation, and Paresthesia = numbness, tingling, burning sensation) To test for sensitivity of a dermatome: heat, cold, a pin, cotton ball, paper clip, the pads of the fingers, or fingernails may be used. The patient, with their eyes closed, should be asked to provide feedback regarding their response to the various stimuli. All tests should be compared bilaterally.

Dermatomes of the Lower Extremity

Cutaneous Distribution of the Lower Extremity


Figure 6


 Figure 7

A cutaneous distribution pattern is an area or patch of skin supplied by a specific sensory peripheral nerve. That nerve maybe be made up of sensory fibers from one or more nerve levels. Here are some examples of lower extremity nerve cutaneous distributions.

Nerve Root

Dermatome Afferent


Myotome Efferent


Functional Application


Touch: Lower abdomen, groin, lumbar region from 2nd to 4th vertebrae, upper and outer aspect of the buttocks

Quadratus Lumburum

Sensation to low back, over trochanter and groin


Touch: Lowe lumbar region, upper buttock, anterior aspect of thigh



-Hip flexion

-Sensation to back, front of thigh to knee


Touch: Medial aspect of thigh to knee, anterior aspect of lower 1/3 of the thigh to just below the patella



-Knee extension, hip flexion

-Sensation to back, upper buttock, anterior thigh and knee, medial lower let


Touch: Medial aspect of lower leg and foot, inner border of foot, great toe

Tibialis Anterior

Extensor Hallucis Longus

Digitorum Digitorum Longus


-Ankle dorsiflexion, subtalar and transverse tarsal inversion

-Sensation to medial buttock, lateral thigh, medial leg, dorsum of foot, great toe


Touch: Lateral border of leg, anterior surface of lower leg, top of foot to middle three toes

Extensor Hallucis Longus

Extensor Digitorum Longus


Gluteus Maximus and Medius


-Great toe extension, subtalar and transverse tarsal inversion

-Sensation to upper lateral leg, anterior surface of the lower leg, middle three toes


Touch: Posterior aspect of the lower ¼ of the leg, posterior aspect of the foot, including the heel, lateral border of the foot and sole



Gluteus Maximus and Medius



-Ankle plantarflexion, knee flexion, subtalar and transverse tarsal inversion

-Sensation to lateral leg, lateral foot, lateral two toes, plantar aspect of foot


Touch: Posterior central strip of the leg from below the gluteal fold to ¾ of the way down the leg



Gluteus Maximus


-Knee Flexion, Ankle plantarflexion, toe flexion

-Sensation to posterior thigh & upper posterior leg

Spinal Ligaments

1. Ligamentum Nuchae

  • Connects spinous processes, runs from external occipital protuberance to C7. Protects against extreme head and neck flexion.

2. Supraspinal

  • Connects tips of spinous processes from C7 to sacrum. Protects against extreme of thoracic and lumbar flexion.

3.Ligamentum Flavum

  • Connects lamina anteriorly from adjacent vertebrae from axis to sacrum. Provides protection to the neural elements of the spine and provides stability by preventing excess motion between vertebrae


  • Connects inner surface of spinous processes of adjacent vertebrae. Protects against extreme spinal flexion.


  • Connects transverse processes of adjacent vertebrae. Protects against the extreme of lateral spinal flexion.

6.Anterior Longitudinal

  • Connects adjacent vertebral bodies, runs from axis to sacrum on “anterior” aspect of vertebral body. Protects against the extreme of spinal extension.

7.Posterior Longitudinal

  • Connects adjacent vertebral bodies, runs from axis to sacrum on “posterior” aspect of vertebral body. Protects against the extreme of spinal flexion.


Figure 12

Figure 13


Figure 14

Figure 15

Selected Major Muscles of the Spine (including skull and pelvis)





Nerve Innervation:

Splenius Cervicis & Capitis




Nerve Innervation:





Nerve Innervation:

Selected Major Muscles of the Spine

Quadratus Lumborum




Nerve Innervation:





Nerve Innervation:





Nerve Innervation:

Selected Major Muscles of the Spine – Erector Spinae Muscle Group

Erector Spinae: Spinalis




Nerve Innervation:

Erector Spinae: Longissimus




Nerve Innervation:

Erector Spinae: Iliocostalis




Nerve Innervation:

Muscles of the Abdominal Wall

Rectus Abdominis




Nerve Innervation:

Internal Abdominal Oblique




Nerve Innervation:

External Abdominal Oblique




Nerve Innervation:

Transverse Abdominis




Nerve Innervation:

Abdominal Aponeurosis

Abdominal Aponeurosis

A large sheet of fibrous connective tissue located anteriorly in the

abdominal region (right and left sides) providing attachment sites for

the external abdominal oblique, internal abdominal oblique, and the

transverse abominus muscles.

  • The linea alba (white line) is where the right and left

abdominal aponeuroses meet in the midline.

  • The tendinous intersections divide the rectus abdominus

muscles into segments and are a continuation of the abdominal


Figure 22

Functions of the Abdominal Wall

Abdominal Considerations

Protection ____________________________

Support of Viscera _____________________

Elimination ___________________________

Forced Expiration ______________________

Stabilization of Trunk and Pelvis __________

Trunk Movement ______________________

Parturation ___________________________

Kinesiology of the Abdominal Muscles: List in order

the importance or degree of involvement of the

abdominals in the following activities.

_____ Straight leg raises (unilateral)   _____ Pull-ups        

_____ Straight leg raises (bilateral)           _____ Curl-ups

_____ Sit-ups                           _____ Ambulation

_____ Push-ups

Causes for weakness of the abdominal wall

  • Developmental
  • Pathological

Abdominal Ptosis: Sagging abdomen

Beevor’s Sign: Looking for umbilicus displacement

Figure 24

Thoracolumbar Fascia

A large sheet of fibrous connective tissue located posteriorly in the

thoracic and lumbar trunk regions (right and left sides) providing

attachment sites for the muscles and to add stability to the trunk.

  • The quadratus lumborum and erector spinae muscle groups are

encased withing the thoracolumbar fascia.

  • The latissimus dorsi attaches into the spinous processes via its

attachment into the thoracolumbar fascia.

  • The thoracolumbar fascia attaches to the transverse and spinous

processes in the lumbar region.

  • Posterolaterally the internal abdominal oblique and transverse

abdominus muscles attach to it.

  • Inferiorly the thoracolumbar fascia attaches to the sacrum and

iliac crest, providing attachment for the gluteus maximus.

  Lower Crossed Syndrome

  • Excessive lordosis of lumbar spine
  • Excessive anterior pelvic tilt

Note: Not always but a lower crossed syndrome will

often be associated with an upper crossed syndrome.


  • Congenital deformity
  • Poor body mechanics
  • Muscle imbalance (disuse or disease)
  • Overtraining in certain sports
  • Compensatory deformity to a kyphosis

or other deformities of foot, knee, or hip


  • More common in tall ectomorphs
  • More common in children and adolescents
  • Asymptomatic unless due to trauma
  • Relationship to low back pain
  • Changes in intervertebral body distance
  • Bony changes uncommon

                                                             Therapeutic Interventions for Lower Crossed Syndrome

In the spaces below identify the muscles that are “weak” and those that are “tight” with respect to Lower Crossed  

Syndrome and then identify therapeutic interventions to help correct the problem.

Therapeutic Intervention – How would you isolate to

strengthen the weak muscles?

Therapeutic Intervention – How would you isolate to

stretch the tight muscles?

Scoliosis – Lateral deviation(s)/curve(s) of the spine with coupled vertebral rotation to the opposite side: Spinous processes rotate                           toward concavity of curve and the vertebral bodies rotate toward the convexity of the curve. The convexity of the curve is the                              reference side of the curve for nomenclature (right convexity = right curve).


  1. Known: (20%) Hemivertebrae,

Congenital spinal deformities, neuron-

muscular problems, leg length difference

cerebral palsy, muscular dystrophy

  1. Unknown: Idiopathic (80%)


  1. Most common in adolescence 10-18
  2. Onset, typically during puberty
  3. Affects 2% women, .5% men
  4. Usually asymptomatic

Idiopathic scoliosis is broken down into four categories based on age:

1) Infantile: children ages 3 and under

2) Juvenile: ages 3 to 9

3) Adolescent: ages 10-18

4) Adult: after skeletal maturity.

The most common form of Scoliosis, representing 80% of idiopathic scoliosis cases, is Adolescent Idiopathic Scoliosis, which                           develops around the onset of puberty. People with a family history of spinal deformity are at greater risk for developing scoliosis.

Early detection is essential.

Signs of Scoliosis – common characteristics:

  1. Shoulder asymmetry
  2. Unilateral scapular prominence and asymmetry
  3. Rotation of trunk (one shoulder forward)
  4. Contour of trunk (waistline), skin folds
  5. Distance from arm to thorax
  6. Deviations of spinous processes
  7. Chest flatness on side of convexity

Figures 27, 28

Adam’s Forward Bend Test: with their feet together

have the patient bend forward, bending 90º at the waist.

  • Rotation of vertebrae with rib prominence

(angulation = Razor back sign) in thoracic


and paraspinal muscle prominence in the



Figure 29

Types/Classifications of Curves

Figure 30

Figure 31


  • Left lumbar
  • Right lumbar
  • Left Thoracic
  • Right Thoracic

Simple “C”

Compound “S” (double

major curve)

                                                                       Degree Curvature and Therapeutic Interventions

If curvature of curve is:

  • <20º = Therapeutic exercise and monitor
  • 20º to 30º = bracing and therapeutic exercise
  • >40º = usually requires surgery
  • >50º = pulmonary limitations

         = significant

         = back bain

         = arthritis

         = degenerative disc disease

Cobb Method for Measuring Degree of Scoliosis

Choose the most tilted vertebrae above and below the

apex of the curve. The angle between intersceting lines

drawn perpendicular to the top of the vertebrae and the

bottom of the vertebrae is the Cobb Angle.

Figure 32


Figure 33

Sample of Review Questions

  1. If a person has a stenosis of his/her interebral foramen at L4, what two trunk movements do you feel would would

tend to provide relief for this patient?

  1. What do you feel is the primary function of the muscles that surround the spinal column?
  2. If a person suffered a herniated disc at the L4-L5 spinal segment, what would be the associated sensory and motor deficits

that could occur?

  1. How might an excessive lumbar lordosis contribute to the development of excessive thoracic kyphosis?
  2. What are some exercises that would strengthen the right quadratus lumborum?
  3. What is the difference between a dermatome and the cutaneous distribution?
  4. Why is there a significant difference in the number of muscles that support the neck posteriorly vs anteriorly?
  5. What could you do as parents to reduce the risk of your child developing a scoliotic condition that would require


  1. Why is there more of a need for a planned exercise program to strengthen the abdominal muscle group as compared

to the back extensor muscle group?

  1. What muscle groups are tight with lower crossed syndrome?

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