Vertebral column Flashcards
Name the 5 functions of the vertebral column
- Carries and protects the spinal cord and nerves
- Provides support to the thoracic cage
- Transfers weight from the upper body to the lower limbs
- Shock absorbing
- Muscle attachment point
Label the parts of the vertebrae
What is the odontoid process?
Part of the C2 vertebrae (axis) that forms a pivot joint with the atlas. Enables rotation of the head
Curvatures of the vertebrae
Cervical - lordosis Thoracic - kyphosis Lumbar - lordosis Sacral - kyphosis Thoracic and sacral curvatures develop during the foetal period and are retained throughout life, cervical and lumbar curvatures do not fully develop until after birth
Features of cervical vertebrae
Small wide body Large triangular vertebral foramen Transverse processes have foramina transversaria (vertebral arteries and sympathetic plexus pass through) Short and bifid spinous processes (C3-C5), C6 and C7 longer
Features of thoracic vertebrae
Heart shaped body with costal facets for articulation with the ribs
Smaller circular vertebral foramen
Long strong transverse processes. Length decreases from T1-T12
Long spinous processes that slope posteroinferiorly. Tip extends to the level of the vertebral body below.
Features of lumbar vertebrae
Large kidney shaped body, larger and heavier than bodies of other vertebrae
Triangular vertebral foramen
Long slender transverse processes.Accessory processes on the posterior surface
Superior articular facets directed medially and inferior articular facets directed anterolaterally. Aligned to resist rotational movements
Short hatchet shaped spinous processes.
Scoliosis
Curved back characterised by lateral curvature and rotation of the vertebrae. Caused by asymmetric weakness of intrinsic muscles of the back, failure of half of the vertebra to develop or a difference in the length of lower limbs.
Features of atlas (C1)
Consists of two lateral masses connected by anterior and posterior arches. No spinous process or body Flat inferior facets articulate with axis
Features of axis (C2)
Strongest cervical vertebra Odontoid process projects superiorly and forms a pivot joint with C1 to allow rotation of the head
Describe the structure of intervertebral joints
Secondary cartilagenous joints (symphyses)
Present from below C2 - above S1 with increasing thickness
Provide strong attachments between vertebral bodies
Articulating surfaces connected by IV discs
Stabilised by supraspinous, interspinous ligaments and ligamenum flavum
Describe the structure of IV discs
Each disc consists of an outer annulus fibrosus and inner nucleus polyposus
Annulus fibrosus: concentric lamellae of fibrocartilage.
Nucleus polyposus: gelatinous central core of IV disc rich in glycosaminoglycans which draws in water (85% water at birth).
Turgid nucleus acts as a semifluid support for vertebrae during movement.
How does the structure of IV discs change with age?
With age, the nucleus polposus dehydrates, elastin and proteoglycans are replaced by collagen. Eventually they become dry andn granular.
The annulus fibrosus then assumes a greater share of the vertical load
Lamellae of annulus fibrosus thickens with age and develops deep fissures and cavities. Degeneration can allow herniation of the NP and IV disc prolapse
Name the ligaments that support the vertebral column (3)
Anterior longitudinal ligament
Posterior longitudinal ligament
Ligamentum flavum
Describe the structure of the 3 ligaments that support the vertebral column
Anterior longitudinal ligament: strong, broad fibrous band that covers and connects the anterolateral aspects of the vertebral bodies and IV discs. Extends from sacrum to C1 and occipital bone. Maintains stability of intervertebral joints and limits extension of the column
Posterior longitudinal ligament: narrower fibrous band that runs within the vertebral canal along the posterior aspect of the vertebral bodies. Mainly attached to the IV discs. Runs from C2 to the sacrum. Helps prevent hyperflexion of the vertebral column and posterior herniation of IV discs.
Ligamentum flavum: Fibrous elastic tissue that extends vertically between lamina of the vertebrae, binding adjoining vertebrae together. Resist separation of the vertebral laminae by stopping abrupt flexion of the vertebral column, thus preventing injury to the IV discs.
What are the three ligaments that lie between vertebrae?
supraspinous ligament (stong)
interspinous ligament (weak)
ligamentum flavum: Help preserve the mornal curvatures of the vertebral column and assist with straightening the column after flexing
Nuchal ligament
Strong medial ligament of the neck. Composed of thickened fibroelastic tissue extending from occipital bone to the spinous processes of C3-C5.
Acts as a site of muscle attachment
What layers do you penetrate in a midvertebral needle insertion?
the skin
supraspinous ligament
interspinous ligament
ligamentum flavum
How do IV discs respond to pressure placed on the vertebral column?
Forces applied to the vertebral column increase pressure in the nucleus polposus which becomes compressed. This tenses the annulus fibrosis. Tension limits movement between vertebral bodies
Role of spinal curvatures
Helps keep centre of gravity in a evenly distibuted in a central position over S1/S2
What can cause changes to spinal curvature?
Age-related kyphosis
Osteoarthritis - IV disc degeneration
Pregnancy - hyper lumbar lordosis
Scoliosis - lateral curvature
Muscular dystophy - weakened spinal muscles. causes hyperlordosis required to stand upright
Muscles of the back (function)
Extrinsic muscles:
Superficial - produce and control limb movements (trapezius, latisimus dorsi, rhomboids). Innervated by anterior rami of spinal nerves (trapz CN XI)
intermediate - produce and control respiratory movements (serratus posterior superior, serratus posterior inferior)
Intrinsic muscles: innervated by posterior rami of spinal nerves and act to maintain posture and control movements of the vertebral column.
Superficial - splenius muscles (keeps head upright)
Intermediate - erector spinae (extend head and vertebrak column)
Suboccipital triangle
Located at the superior part of the back of the neck, inferior to the occipital region of the head.
Triangle lies deep to trapezius. Contains vertebral artery and suboccipital nerve (C1)
Significance:
Winding course of vertebral arteries through foramen transversaria and suboccipital triangle becomes clinically significant when blood flow is reduced. Prolonged turning of the head causes light-headedness, dizziness and blackouts.
How do abdominal muscles support the vertebral column?
External oblique, internal blique and transversus abdominus laterally rotate the trunk (and vertebral column)
Contracting abdominal muscles against a closed glottis provide a pneumatic cushion to support the vertebral column. This helps keep it upright
Rectus abdominus helps maintain stability of the lumbar spine
