The Back Flashcards
Functions of the vertebral column
Enables upright posture
Supports body weight
Protects and transmits spinal cord and spinal nerves
Supports the skull and allows for its movement
Contributes to the thorax (ribcage)
Locomotion : Provides attachment for trunk muscles
Describe the vertebral column
SPINE
Series of irregular bones, vertebrae
x7 - Cervical
x12 - Thoracic
x5 - Lumbar
x5 - Sacral (fused to 1 sacrum)
x1-4 - Coccygeal (fused)
How are the vertebrae separated ?
BY fibro-cartilaginous intervertebral discs
Describe the general morphology of the vertebral column
The vertebral column has primary and secondary curvatures.
Primary curvatures
- Present in-utero
- In the thoracic and sacral regions
- concave anteriorly (KYPHOSIS)
Secondary curvatures
- Don’t develop until the infant lifts his/her head and stands to walk (develop as myelination occurs)
- Found in cervical and lumbar regions
- Are concave posteriorly (LORDOSIS)
Kyphosis
Concaved anteriorly
Thoracic and Sacral
Lordosis
Concaved posteriorly
Cervical and Lumbar
Describe the features of the typical vertebrae, from each region
Intervertebral surface (endplate)
Pedicle
Lamina
Vertebral foramen -> canal
Transverse process
Superior vertebral notch
Inferior vertebral notch
Superior articular process (FACET)
inferior articular process (FACET)
Vertebral foramen function
Protects and transmits spinal cord and spinal nerves
What are the articular facets and joints susceptible to ?
Arthritis
Back Pain
Where is the superior articular process (facet) found ?
At the junction between the pedicle and lamina
Describe the cervical region of vertebrae
Spinous process - short and bifid, except C7
Vertebral body - small
Superior Articular Facet
Ulcinate processes
Transverse foramen
Posterior tubercle - Transverse process
Describe the thoracic region of vertebrae
These contribute to the formation of ribcage by articulating with the ribs.
Superior articular facets - flat and facing potero-laterally, on the arc of a circle —> allows rotation
Transverse process with a transverse costal facet for articulation with the tubercle of its own rib.
Spinous process, long and pointing inferiorly, overlapping 2 vertebrae.
Costal Demi-facets, upper demi-facet for articulation with head of own rib, lower Demi-facet is for articulation with the rib below.
Describe the lumbar region of vertebrae
Largest body
Superior Articular facets - concave and facing postero-medially, interlocking with inferior facets.
Spinous process - sturdy, stumpy, quadrangular
Extension is greatest movement –> flexion and some lateral flexion, but no rotation.
Describe the sacrum region of vertebrae
Formed by the fusion of 5 vertebrae
Link between the spine and iliac bones –> pelvis –> lower limbs
Sacral promontory
Posterior sacral foramen
Anterior sacral foramen
Sacral canal
Median, intermediate, lateral crests
Sacral hiatus
Importance of sacral hiatus
Important in anaesthesia (with coruna)
Sacral canal function
Contains the caudal equina
Anterior and Posterior sacral foramen function
Anterior : anterior rami of spinal nerves pass
Posterior : posterior rami of spinal nerves pass
Median, Intermediate and Lateral crests
Projections from the sacrum : median (centre), intermediate (middle), lateral (outer)
Importance of the sacral promontory
It is the anterior projection of the S1 and is important in females.
It is said that the normal female sacrum tends to be flat while the normal male sacrum tends to be more curved.
Describe the atlas
C1 - Cervical 1
Holds the skull, doesn’t have a vertebral body.
Occipital condyles articulate with the superior articular facets
Anterior and posterior arches connection lateral masses.
Lateral mass, with superior and inferior articular facets.
Describe the axis
C2 - Cervical 2
Rotation of the head and neck at the atlanto-axial joint.
Odontoid process or Dens, for articulation with the anterior arch of the atlas.
Tooth - on top of the body
Superior Articular Facets - articulate with the inferior articular facets of the atlas.
Function of transverse foramen
Houses vertebral arteries and veins
Vertebra prominens
C7
Describe the features of the atypical vertebrae, from each region
Atlas
Axis
Zygapophyseal (facet) joint
Synovial joints between articular processes (spinal processes)
Intervertebral foramen
Gaps through which the spinal nerve emerges and is formed by superior and inferior vertebral notches, with contribution from the disc.
Symphysis joint
(Secondary cartilaginous joint)
Found between endplates and the intervertebral discs
(found between bodies of vertebrae)
Functions of intervertebral discs
Contributes to the shape of the spinal curvatures
20-25% of the length of the column
Describe the structure of intervertebral discs
Consists of an outer annulus fibrosus, which surrounded a central nucleus pulposus.
Sits on top of the vertebral endplate.
Nucleus pulposus
Gelatinous, 70-90% water, relative collagen content increases with age
Absorbs compressive forces between vertebrae.
Annulus fibrosus
Very strong, concentric lamellae of fibrocartilage
Attached and kept in place by anterior and posterior longitudinal ligaments.
Describe supply to the intervertebral disc
Periphery of the disc is supplied by neighbouring capillaries.
Centre is nourished by diffusion from the body of the vertebra.
Describe clinical relevance of intervertebral discs
Discs may deform to allow movement between the vertebral bodies.
This may put pressure on the nucleus pulposus.
The annulus fibrosus may degenerate and weaken.
Describe herniated disc
The nucleus may herniate or prolapse to compress :
- the spinal cord (which ends at L1/2)
- the caudal equina
- an emerging spinal nerve
Describe a herniated L4/5 disc
The central position of the posterior longitudinal ligament means that most disc herniations are posterolateral, towards the intervertebral foramen.
The disc forms the anterior aspect of the foramen, but inferiorly, the spinal nerve probably emerges above the prolapsing disc and escapes injury.
A prolapsed L4/5 disc is likely to compress the L5 (and lower) nerves.
Name the ligaments that support the vertebral column
Atlanto-Occipital and Anterior Atlanto-Axial Membranes
Tectorial Membrane
Alar ligament
Transverse ligament of atlas
The ligamentum flavum
The posterior longitudinal ligament
Anterior longitudinal ligament
Ligamentum Nuchae
Supraspinous ligament
Interspinous ligament
Atlanto-Occipital and Anterior Atlanto-Axial Membranes
They continue downwards as anterior longitudinal ligaments.
Tectorial Membrane
Ends between the foramen magnum and C2, and continues as posterior longitudinal ligament.
Alar ligament
Prevents excessive rotation
Transverse ligament of atlas
Keeps the dens close to the anterior arch
The ligamentum flavum
This extends between the vertebral laminae and limit sudden flexion.
The posterior longitudinal ligament
On the posterior surfaces of the bodies of vertebrae between C2 to sacrum, limiting hyper-flexion.
Anterior longitudinal ligament
On the anterior surfaces of the vertebral bodies between Atlas to the sacrum that limits extension.
Ligamentum Nuchae
Nuchal Ligament which extends between occipital bone and spinous process of C7 to limit flexion and provide muscle attachment.
Supraspinous ligament
Found between the tips of spines and run between sacrum to C7
Interspinous ligament
May be damaged in whiplash injury
Briefly describe the vascular supply of the vertebral column
Arteries form anastomotic rings that arise form the vertebral arteries and posterior intercostal and lumbar branches of aorta.
Venous plexuses (internal and external) coalesce and drain to the veins equivalent to the above arteries.
Clinical relevance of venous plexuses
They facilitate tumour spread
e.g. prostate gland
How can muscles of the back be classified ?
Extrinsic or Intrinsic, based on embryological origin and type of innervation.
Describe extrinsic muscles
Derivatives of hypo axial myotome
Superficial
Involved with movements of the upper limbs and thoracic wall
Innervated by anterior rami of spinal nerves.
Describe intrinsic muscles
Derivatives of epaxial myotome
Located deep, between the spinous processes and the angle of ribs.
Adapted to provide support and movement in resistance to the effect of gravity.
Move the vertebral column
Participate in moving the head
Innervated by the posterior rami of spinal nerves
How are intrinsic muscles stronger than the flexors ?
As extension (such as lifting an object) is in opposition to gravity.
What is the function of layer 1 muscles in the back ?
Superficial layers that are mainly for upper limb movement
What muscles are found in layer 1 of the back ?
Trapezius
Latissimus dorsi
Describe the trapezius muscle
From skull, spinous processes to scapula and clavicle (laterally)
Upper fibres elevate and rotate shoulders during abduction of the arm.
Supplied by spinal accessory nerve.
Describe the latissimus dorsi
Iliac crest, fascia, spines of T6 to T12, lower ribs; to humerus
Shoulder extension and adduction
Supplied by the Thoracodorsal nerve
What muscles are found in layer 2 of the back ?
Levator scapulae
Rhomboid major and minor
Serratus posterior superior
Serratus posterior inferior
Levator scapulae
Scapular elevation
Rhomboid major and minor
Scapular retraction and elevation
Serratus posterior superior
Inspiration
Serratus posterior inferior
Expiration
What muscles are found in layer 3 of the back ?
Intrinsic back muscles
From the skull, though cervical, thoracic and lumbar regions to pelvis.
Keep the vertebral column upright and in extension against gravity.
Arranged in 3 layers :
- Superficial
- Intermediate
- Deep
Function of muscles found in the 3rd layer of the back
Keep the vertebral column upright and in extension against gravity.
Superficial layer of 3rd layer of muscle
Splenius capitis and cervicis
Acting together : extend the neck and/or head
Acting alone : rotate and laterally flex
Intermediate layer of 3rd layer of muscle
Erector Spinae
Keeps us upright
3 columns
- Iliocostalis
- Longissimus
- Spinalis
Deep layer of 3rd layer of muscle
Transversospinalis
- Rotatores
- Multifidus
- Semispinalis
Deep neck muscles
Obliquus captis : superior/inferior
Rectus capitis posterior major/minor
Sub-occipital triangle
Function of the sub-occipital triangle
Transmits vertebral artery and vein as well as the sub occipital nerve.
- Vertebral artery
- Vertebral vein
- Suboccipital nerve
