kin191 a.ch.10. lumbar. thoracic. anatomy
TRANSCRIPT
KIN 191AAdvanced Assessment of Lower Extremity Injuries
THE THORACIC AND LUMBAR SPINEANATOMY
INTRODUCTION
• BONY ANATOMY• ARTICULATIONS• LIGAMENTOUS ANATOMY• MUSCULAR ANATOMY• NEUROANATOMY
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• Cervical spine (7)– Greatest ROM– Spinal cord is the most vulnerable
• Thoracic spine (12)– Greatest protection of the spinal cord expense
of ROM because of large spinous process• Lumbar spine (5)– An equal balance between protection of the spinal
cord and available ROM• Sacrum (5) and coccyx (3~4)– Composed of fused bone– To affix the spinal column to the pelvis– Serve as a site for muscle attachment
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Spinal Column
• The segments of the mobile spinal column
• Cervical (n=7), thoracic (n=12), and lumbar (n=5) vertebrae
• Discs: 23
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Bony Anatomy (Lumbar)
• Total of 5 lumbar vertebrae• Components– Vertebral body– Transverse processes– Spinous process – Neural arch– Pedicle – Lamina
– Pars interarticularis– Intervertebral
foramen– Facet joints (superior
and inferior)
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Vertebral Body
Transverse Processes
Inferior Articular Facets
Spinous Process
Superior Articular Process
Lamina
Pedicle
• Vertebral body– Primary weight-bearing structure of
spine• Transverse processes– Attachment site for ligaments/muscles– Long for leverage/increasing
mechanical advantage• Spinous process– Attachment site for ligaments/muscles– Posterior projection (no inferior slant)
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• The Neural Arch– Formed by the pedicle and
lamina on each side• Pedicle – vertebral body to
transverse process• Lamina – transverse process to
spinous process
– Serves as the protective tunnel through which the spinal cord passes
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Pedicle
Lamina
• Pars Interarticularis– Between the superior and inferior
facets of the vertebra– A common site of stress fractures
in lumbar spine
• Intervertebral Foramen– The vertebral notch on the
inferior portion of one pedicle is matched with the vertebral notch on the superior portion of the pedicle below
– Nerve roots existing between the vertebrae
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• Facet joints (superior and inferior)– 2 sets for each vertebrae – articulation between
vertebral segments– Lumbar facet orientations• L1-L3 – sagittal plane• L4-L5 – frontal plane
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Intervertebral Disc• Dual purposes– Shock absorption (longitudinal and rotational)– Increase available ROM
• Components– Annulus (ring) fibrosus – tough/dense outer layer– Nucleus (cell)pulposus – flexible inner layer– “Jelly doughnut”
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• 23 intervertebral discs are found along the spinal column
• No disc between– C0-C1 (the skull and the first cervical vertebrae)– C1-C2
• Individual disc are referenced by the vertebrae between which they are found– The disc located between the fourth and fifth
lumbar vertebrae is known as the L4-L5 intervertebral disc
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• Permanent dehydration– Occurs through the aging process– Until the age of approximately 40 years, the
disc is fully hydrated after this age dehydration begins
– By age 60 years, the disc have reached their maximum state of dehydration• Decreasing ROM • A slight narrowing of the intervertebral foramen
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Nucleus Pulposus
• Elastic/gelatinous substance – 60-70 % of H20 content
• Deformable but resistant to compression• Affects of bipedal ambulation and aging
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Bony Anatomy (Thoracic)• Vertebral bodies– Smaller in thickness and diameter than lumbar
vertebral bodies
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• Spinous processes– Project inferiorly to limit extension ROM– Continue to serve as muscular and ligamentous
attachment sites
• Transverse processes– Thicker to allow for formation of costotransverse
joints on ribs 1-10– Ribs 11-12 are “floating” so no articulation with
transverse processes
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• Costovertebral joints– Articulation between each rib and thoracic spine
vertebral bodies– For T1 and T10-12, articulation with 1 rib on each
side (1 facet in middle)– For T2-T9, articulation with 2 ribs on each side at
inferior and superior costal facets
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• Ribs– True ribs (1-7) articulate with sternum through
own costal cartilages– False ribs (8-10) articulate with sternum through
conjoined costal cartilage– Floating ribs (11-12) have no anterior articulation
• Sternum– Manubrium (superior)– Body– Xiphoid process (inferiorly)
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ARTICULATIONS
• Synovial joints (joint capsule)– Superior and inferior facet joints
• Cartilaginous joints– Intervertebral disc and superior/inferior vertebral
bodies• Each segment has relatively little individual
mobility, but in combination allow for significant trunk/spine ROM
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Ligamentous Anatomy
• Anterior longitudinal ligament– Broad/thick, attaches to anterior aspect of
vertebral bodies and intervertebral discs– Limits spine extension (thinnest in lumbar area)
• Posterior longitudinal ligament– Thins distally, lines anterior portion of vertebral
foramen, limited intervertebral disc attachment– Limits spine flexion
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Ligamentous Anatomy
• Supraspinous ligament– Attaches tips of spinous processes together
• Interspinous ligaments– Fills space between adjacent spinous processes– Limit spine flexion and rotation
• Ligamentum flavum– Connect laminae of adjacent vertebrae– Reinforces facet joints
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A: Ligamentum flavum
B: Interspinous ligament
C: Supraspinous ligament
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MUSCULAR ANATOMY
• Extrinsic muscles– Rectus abdominus• Responsible primarily for trunk flexion
– Internal/external obliques (pocket muscle)• Responsible for lateral bending and/or spine rotation
– Transverse abdominus• Trunk stabilization
– Latissimus dorsi• Trunk stabilization via thoracolumbar fascia
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Abdominal Muscles
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• Intrinsic muscles– Quadratus lumborum – pelvis to transverse
processes– Erector spinae muscles (lumborum categorization)
– pelvis/sacrum and spinous processes to transverse processes)• Iliocostalis – most lateral
– Lumborum/Thoracis/Cervicis• Longissimus – intermediate
– Thoracis/Cervicis/Capitis• Spinalis – medial
– Thoracis/Cervicis/Capitis
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– Transversospinal muscles – transverse process to spinous process• Multifidus • Rotatores • Semispinalis
– Thracis/Cervicis/Capitis
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Muscular Anatomy
• Extrinsic muscles – indirect effect on spinal column– Latissimus dorsi• Spine extension and stabilization via fascia
– Rhomboid major and minor• Stabilization of thoracic spine and scapular adduction
– Trapezius (middle and lower fibers)• Stabilization of thoracic spine
• Will be covered in KIN 191B33
NEUROANATOMY
• Lumbar plexus• Sacral plexus
• Nerve roots named for spinal segment superior to corresponding nerve root level– L4 nerve root exits spinal column below 4th lumbar
vertebrae
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Lumbar Plexus
• Primarily arises from L2, L3, L4 nerve roots• Posterior (dorsal) branches combine to form
femoral nerve– Femoral nerve – posterior division of L2-L4
• Anterior (ventral) branches combine to form obturator nerve– Obturator nerve – anterior division of L2-L4
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Lumbar Plexus
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Sacral Plexus
• Primarily arises from anterior branches of L4 and L5 as well as S1 through S3
• Anterior (ventral) branches of L4-S3 combine to form tibial nerve– Tibial nerve – anterior division of L4-S3
• Posterior (dorsal) branches of L4-S2 combine to form common peroneal nerve– Common peroneal nerve – posterior division of
L4-S2
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Sacral Plexus
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Sacral Plexus
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