Section 10 - Trunk & Spinal Column
Learning Outcomes: Students will be able to: - Describe the musculoskeletal anatomy of the spinal column, trunk, ribcage and associated connective tissues that support these joints.
- Articulate the functional design of the atlantooccipital and intervertebral joints and the osteokinematic and arthrokinematic movements possible at the joints.
- Describe the origin, insertion, actions, and nerve innervation of select muscles that act on the lumbar, thoracic, and cervical joints.
- Identify how to strengthen and stretch each of the muscles or muscle groups that act upon the segments of the spinal column.
- Articulate the mechanisms that can contribute to pathology of intervertebral joints and discs, and the proper techniques to reduce the risk while enhancing performance.
- Identify spinal and lower extremity pathologies related to vertebral disc and other spinal pathology using knowledge of myotomes, dermatomes, and cutaneous distribution patterns.
- 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
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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:
- Provide structural support for the body (support for head and transmittal of weight to the pelvis)
- Allow for movement (the summation of 25 spinal segments together allow significant movement)
- Protect the spinal cord (bony protection)
- 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).
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Figure 2 |
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.
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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.
- 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.
- 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.
- Vertebral Endplate: composed of hyaline articular cartilage and fibrocartilage, it lines the articulating surfaces of each vertebral body.
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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.
- Dermatome: An area or band of skin innervated by sensory fibers of a single nerve root level.
- Myotome: A muscle or group of muscles innervated predominately by motor fibers of a single nerve root level.
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.
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: (www.youtube.com/watch?v=rKiTwagLYck)
Lower Extremity Myotomes |
Nerve Root Level | Patient Position | Joint & Movement Resisted (tested) |
L1-L2 | Sitting | Hip flexion
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L3 | Sitting | Knee extension
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L4 | Long sit | Ankle dorsiflexion
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L5 | Long sit | Big toe extension
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S1 | Prone | Ankle plantarflexion, Foot eversion, and Hip extension
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S2 | Prone | Knee flexion
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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
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 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 (Sensory) | Myotome Efferent (Motor) | Functional Application |
L1 | 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 |
L2 | Touch: Lowe lumbar region, upper buttock, anterior aspect of thigh | Iliopsoas Quadriceps | -Hip flexion -Sensation to back, front of thigh to knee |
L3 | Touch: Medial aspect of thigh to knee, anterior aspect of lower 1/3 of the thigh to just below the patella | Psoas Quadriceps | -Knee extension, hip flexion -Sensation to back, upper buttock, anterior thigh and knee, medial lower let |
L4 | Touch: Medial aspect of lower leg and foot, inner border of foot, great toe | Tibialis Anterior Extensor Hallucis Longus Digitorum Digitorum Longus Peroneals | -Ankle dorsiflexion, subtalar and transverse tarsal inversion -Sensation to medial buttock, lateral thigh, medial leg, dorsum of foot, great toe |
L5 | Touch: Lateral border of leg, anterior surface of lower leg, top of foot to middle three toes | Extensor Hallucis Longus Extensor Digitorum Longus Peroneals Gluteus Maximus and Medius Dorsiflexors | -Great toe extension, subtalar and transverse tarsal inversion -Sensation to upper lateral leg, anterior surface of the lower leg, middle three toes |
S1 | 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 | Gastrocnemius Soleus Gluteus Maximus and Medius Hamstrings Peroneals | -Ankle plantarflexion, knee flexion, subtalar and transverse tarsal inversion -Sensation to lateral leg, lateral foot, lateral two toes, plantar aspect of foot |
S2 | Touch: Posterior central strip of the leg from below the gluteal fold to ¾ of the way down the leg | Gastrocnemius Soleus Gluteus Maximus Hamstrings | -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
4.Interspinal - Connects inner surface of spinous processes of adjacent vertebrae. Protects against extreme spinal flexion.
5.Intertransverse - 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.
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Figure 13  Figure 14 
Figure 15 |
Selected Major Muscles of the Spine (including skull and pelvis) |
Sternocleidomastoid Origin:
Insertion:
Actions:
Nerve Innervation: | 

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Splenius Cervicis & Capitis Origin:
Insertion:
Actions:
Nerve Innervation: |
Suboccipitals Origin:
Insertion:
Actions:
Nerve Innervation: |
Selected Major Muscles of the Spine |
Quadratus Lumborum Origin:
Insertion:
Actions:
Nerve Innervation: | 
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Rotatores Origin:
Insertion:
Actions:
Nerve Innervation: |
Multifidus Origin:
Insertion:
Actions:
Nerve Innervation: |
Selected Major Muscles of the Spine – Erector Spinae Muscle Group |
Erector Spinae: Spinalis Origin:
Insertion:
Actions:
Nerve Innervation: | 
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Erector Spinae: Longissimus Origin:
Insertion:
Actions:
Nerve Innervation: |
Erector Spinae: Iliocostalis Origin:
Insertion:
Actions:
Nerve Innervation: |
Muscles of the Abdominal Wall |
Rectus Abdominis Origin:
Insertion:
Actions:
Nerve Innervation: | 
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Internal Abdominal Oblique Origin:
Insertion:
Actions:
Nerve Innervation: |
External Abdominal Oblique Origin:
Insertion:
Actions:
Nerve Innervation: |
Transverse Abdominis Origin:
Insertion:
Actions:
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 Aponeurosis.
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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.
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Lower Crossed Syndrome - Excessive lordosis of lumbar spine
- Excessive anterior pelvic tilt
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| Note: Not always but a lower crossed syndrome will often be associated with an upper crossed syndrome.
Causes - 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
Considerations - 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
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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?
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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). |
Causes - Known: (20%) Hemivertebrae,
Congenital spinal deformities, neuron- muscular problems, leg length difference cerebral palsy, muscular dystrophy - Unknown: Idiopathic (80%)
| Considerations - Most common in adolescence 10-18
- Onset, typically during puberty
- Affects 2% women, .5% men
- Usually asymptomatic
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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.
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Signs of Scoliosis – common characteristics: - Shoulder asymmetry
- Unilateral scapular prominence and asymmetry
- Rotation of trunk (one shoulder forward)
- Contour of trunk (waistline), skin folds
- Distance from arm to thorax
- Deviations of spinous processes
- Chest flatness on side of convexity
| Figures 27, 28 
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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 area and paraspinal muscle prominence in the lumbar area.
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Figure 29 |
Types/Classifications of Curves 
Figure 30 | 
Figure 31 | Nomenclature - Left lumbar
- Right lumbar
- Left Thoracic
- Right Thoracic
Simple “C”
Compound “S” (double major curve)
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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 |
- 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?
- What do you feel is the primary function of the muscles that surround the spinal column?
- 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?
- How might an excessive lumbar lordosis contribute to the development of excessive thoracic kyphosis?
- What are some exercises that would strengthen the right quadratus lumborum?
- What is the difference between a dermatome and the cutaneous distribution?
- Why is there a significant difference in the number of muscles that support the neck posteriorly vs anteriorly?
- What could you do as parents to reduce the risk of your child developing a scoliotic condition that would require
surgery?
- 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?
- What muscle groups are tight with lower crossed syndrome?