MSS22 Anatomy Of The Spine Flashcards
Vertebral column general features
- 24 individual vertebrae
- fused sacrum (S1-5) and coccyx (Co1-4)
- 33 total
- each articulate with one superior and one inferior
Vertebral column functions
- Provide vertical support for body and head
- Houses and Protects spinal cord
- Maintain upright body posture
Vertebral column regions
5 regions:
- Cervical
- Thoracic
- Lumbar
- Sacral
- Coccyx
Spinal curvatures
4 spinal curvatures (連續兩個S):
- Cervical (內)
- Thoracic (外)
- Lumbar (內)
- Sacral (外)
Functions:
- Give column flexibility
- Biomechanical support of body weight > straight spine
Primary curvatures
- Thoracic + Sacral
- Concave anteriorly (外)
- Newborn: only primary curvatures
Secondary curvatures
- Cervical + Lumbar
- cervical: appear when child raises head (3-4 months)
- lumbar: appear when child stand (by 1st year)
- appear after birth
- Concave posteriorly (內)
- help shift trunk weight over the legs
Spinal curvature abnormalities
- Kyphosis
- exaggerated Thoracic curvature
- results from osteoporosis / poor posture
- “hunchback” look - Lordosis
- exaggerated Lumbar curvature
- results from added abdominal weight (obesity)
- “Donald duck walk” - Scoliosis
- abnormal lateral curvature (usually at Thoracic spine)
- may require back brace / surgery
Vertebrae
2 parts:
- Body (thick anterior weight-bearing structure)
- Vertebral arch (posterior to body)
Both parts enclose:
- Vertebral foramen
- Vertebral canal (spinal canal)
- formed by stacked vertebral foramina
- contains spinal cord
Vertebral arch
Composed of:
- 2 Pedicles from posterolateral margins of body
- 2 Laminae extending posteromedially from edge of pedicle
7 processes:
- 1 Spinous process (project posteriorly from ***laminae junction)
- 2 Transverse processes (lateral projections on both sides of vertebral arch)
- 2 Superior + 2 Inferior articular processes
- -> originate at ***pedicle-lamina junction
- -> each with smooth surface (articular facet)
- -> inferior facet articulate with superior facet of next vertebrae below (facet joint: ***synovial joint)
Intervertebral foramina (=/ vertebral foramen) (nerve root canal)
- Lateral opening between adjacent vertebrae (between 2 pedicles)
- Passageway for spinal nerves + blood vessels (左右出)
Intervertebral discs
- **Fibrocartilage pads lies between 2 vertebral bodies, consists of 2 parts:
- Anulus fibrosus (outer ring)
- Nucleus pulposus (inner gelatinous region)
Functions:
- Shock absorbers between vertebral bodies
- Allow vertebral column to bend
Joints of vertebral column
2 different joints:
- Between vertebral ARCHES
- Articulation of superior-inferior articular processes (facet joint)
- ***Synovial joint - Between vertebral BODIES
- joined by intervertebral discs
- made of fibrocartilage –> type of ***Cartilaginous joint (aka Symphysis)
Ligaments of vertebral column
6 major ligaments:
- Anterior / Posterior longitudinal ligaments
- long ligaments running length of vertebral column
- cover vertebral bodies and intervertebral discs - Ligamentum flavum
- connect laminae of adjacent vertebrae - Intertransverse ligament
- connect transverse processes of adjacent vertebrae - Interspinous ligament
- connect spinous processes of adjacent vertebrae (塊狀) - Supraspinous ligament
- connect tips of spinous processes from C1-C7 adjacent vertebrae –> down to sacrum (條狀)
Vertebral trends
- Smallest near skull –> Larger as weight-bearing ↑
- NO anatomic discrete “cutoffs” between regions: similarities between adjacent vertebrae
Cervical vertebra
- C1-C7
- 3 distinguishable features:
1. Triangular vertebral foramen
2. **Bifid spinous process
3. **Transverse foramen - -> holes in transverse processes
- -> give passage way to Vertebral artery + vein, sympathetic nerves
Direction of articular facets:
Superior: Posterosuperior
Inferior: Anteroinferior
C1, C2:
- highly specialized and form unique set of articulations
- -> provide great mobility to skull
C1 (Atlas):
- NO body / spinous processes
- 2 ***Lateral masses connected by Anterior + Posterior arches
- -> serve as ring for skull to rest upon
- joint between C1 and skull provide 50% of flexion/extension in neck (***nodding)
- articulates in pivot joint with Dens / Odontoid process of C2
C2 (Axis):
- ***Dens / Odontoid process
- -> projects up from the body
- -> pivot for ***lateral rotation between C1 and skull
- ***Atlantoaxial joint between C1 and C2
- -> provided 50% of side-to-side turning in the neck (***shaking)
- -> NO IV disc
C7 (Vertebra Prominens):
- ***NON-bifided spinous process longer than other cervical vertebrae
- easily palpated between scapula
Thoracic vertebrae
- T1-T12
- 3 distinguishable features:
1. Heart-shaped vertebral body
2. Articulate facets on sides of **vertebral body and **transverse processes –> articulate with ribs
3. Spinous processes: long + slant inferiorly
Direction of articular facets:
Superior: Posterolateral
Inferior: Anteromedial
Ribs
12 corresponding ribs:
- each articulates with 2 vertebrae (superior + inferior articulate facets)
- 1, 11, 12 articular with single vertebra only
- 1-7: true ribs
- 8-12: false ribs
- 11, 12: floating ribs
Lumbar vertebrae
- L1-L5
- 5 distinguishable features:
1. Large and Kidney-shaped vertebral body
2. Triangular vertebral foramen
3. Articular processes have nearly **vertical facets (垂直的板)
4. Transverse process: long + slender
5. **Spinous process: short + broad (for attachment of muscles and ligaments –> stabilize lower back)
Direction of articular facets:
Superior: Medial
Inferior: Lateral
Sacral vertebra
- S1-S5 fused vertebra
- **Features:
- Triangular shape
- Concave anterior and posterior surface
- Forms posterior wall of pelvic cavity
Female: wider, shorter, more concave
Male: longer, less wide
Sacral canal
- continuation of vertebral canal
- terminates in inferior opening: Sacral hiatus (Epidural anaesthesia given through it to block ***Pelvic nerves)
- Sacral cornua: bony projections on either side
Coccyx
- Co1-Co4
- Smallest, most inferior bone in spine
- 4 coccygeal vertebrae fused together
- anchor several muscles and ligaments in pelvic region
- acts as one of the bones that bears body weight while sitting
Movement of vertebral column
Range of movement:
- Flexion / Extension
- Left / Right side bending
- Left / Right rotation
Depend on 2 factors:
- Facet joints / Articulation plane: determine range and type of movement
- Muscles: determine control and strength of movement
***Regional difference in articulation plane
Cervical:
AP in ***Coronal plane –> allow Flexion + Extension
Thoracic:
AP in ***Arc of circle –> allow Rotation
Lumbar:
AP in ***Sagittal plane –> allow Flexion, Extension, Lateral bending (little rotation)
Muscles of back
Deep / True / Intrinsic muscles:
- support and move vertebral column (including head)
- 2 groups:
- Extensors (3 layers)
- Superficial (Splenius muscle)
- Intermediate (Erector spinae muscles)
- Deep (Transversospinal muscles) - Flexors (located in neck / lower back / abdomen)
Intrinsic extensor back muscles
Actions:
- Bilaterally (兩邊一齊contract): extends head / spine
- Unilaterally (其中一邊contract): rotates / lateral flexes head / spine
Superficial group (Spinotransverse) (run from skull to early thoracic area)
- Splenius capitis
- Splenius cervicis
Intermediate group (Erector spinae muscles / Sacrospinalis) (run the length of the spine) (***SLI)
- Spinalis (medial)
- Longissimus (middle)
- Iliocostalis (lateral)
Deep group (***TransRMS,Inter,Inter)
- Transversospinalis
- Rotatores (1 vertebra)
- Multifidus (2-4 vertebrae)
- Semispinalis (>5 vertebrae) - Interspinalis
- Intertransversarii
Deep flexor muscles
Confined anterior of spine at Cervical + Lumbar regions
Actions:
- Bilaterally: flexes head / spine
- Unilaterally: rotates / lateral flexes head / spine
- -> Work against gravity e.g. sit-ups
Flexors of Cervical spine:
- Longus colli
- Scalenes (anterior, middle, posterior)
- Sternocleidomastoid (SCM)
Flexors at the Hip:
- Quadratus lumborum
- Psoas major
Flexors of Lumbar spine:
- Rectus abdominis
- Obliques
Radiology of spine
Look at irregularities at 4 lines:
- Anterior vertebral
- Posterior vertebral
- Spinal Laminar
- Spinous process
Herniated / Prolapsed IV discs
Nucleus pulposus protruding through Anulus fibrosus
- -> Bulging of disc contents into vertebral canal
- -> presses spinal cord / spinal nerves
- -> neurological symptoms: pain, sensory deficit, paralysis
- -> Cervical / Lumbar discs most commonly injured
