14 - Bones and Joints of the Back Flashcards
Anatomical delineation of the back
1) Runs between 1st thoracic vertebra and coccyx 2) Lies between medial borders of scapulae and iliac crests
Proportion of skin that is on the back
~18% of body skin
Secondary lordotic curves of the back
First to develop is below neck. Second is in lumbar spine
Cranial shift
When 7th cervical vertebra develops rib, and 12th thoracic vertebra has a smaller rib than usual. Can result in nerve compression, is in ~1% of population
Caudal shift
When T12 rib is very elongated Small rib present on L1
Superficial back muscles
Muscles that have origin on back and insert into somewhere other than the back (EG: onto arms)
Deep back muscles
Muscles that have origin and insertion on back
Major difference between lumbar and thoracic vertebra
Thoracic vertebra have articular facets for ribs
What passes over pedicles in vertebrae?
Spinous nerve
Name for narrowing of verteba between articular processes
Pars inter-articularis
Significance of the pars inter-articularis
A place of structural weakness in the spine
Orientation of S1 facet surfaces
In the coronal plane
Which vertebra articulares with the sacrum?
L5
Where do the sacral veins enter the sacrum?
Sacral formaninae
When are primary centres of ossification present?
In utero, starting between 6 and 8 weeks
Number of primary centres of ossification in vertebrae
Three during development (one in the body, one in each neural arch)
Number of secondary centres of ossification in vertebrae
Five during puberty. One at tip of spinous process, one at tip of transverse process, one on top and bottom of body (annular epiphyses).
Why are twisting movements hazardous to the spine?
Annulus fibres point in alternating directions (are layered). Only 50% of annulus fibres resist force in one lateral direction
Ligaments of lumbar spine 1) 2) 3) 4) 5)
1) Anterior longitudinal ligament (runs up anterior surface) 2) Posterior longitudinal ligament (runs on posterior surface of spine, in intervertebral canal) 3) Intertransverse ligaments (run in between transverse processes) 4) Supraspinous ligament (runs on top of spinous processes) 5) Interspinous ligaments (run between spinous ligaments)
Ligaments within intervertebral canal
1) Posterior longitudinal (expans when passing over IV discs) 2) Ligamentum flavum
Ligamentum flavum
Joins vertebral arches, passes between pedicles. Lies within intervertebral canal. Is elastic
Iliolumbar ligament
Joins L5 and iliac crest. Transmits forces from lumbar spine to pelvis
Ligament that joins L5 and iliac crest
Iliolumbar ligament
Part of IV disc that is innervated
Outer 1/3 of disc
Nerve supply of IV discs
Recurrent meningeal nerve from nerve root
What supplies fibrous capsule of articular synovial joints with innervation?
Posterior rami
What do posterior rami innervate?
Intrinsic muscles of the back, skin of the back, joints. Has both sensory and motor neurons
Neurons in anterior horn
Motor neurons
Neurons in posterior horn
Sensory neurons
Plane of thoracic spinal facets
Coronal
Plane of lumbar spinal facets
Saggital
Orientation of spinal facets between L5 and S1
Used to prevent sliding of L5 into pelvis (lysthesis)
Where does the spinal cord terminate in adults?
L1/L2
Contents of vertebral canal 1) 2) 3) 4)
1) Spinal cord 2) Meninges (dura mater, arachnoid mater, pia mater) 3) Longitudinal veins 4) Internal vertebral venous plexus
Do veins in the body cavity have valves or not?
No valves
Organisation of spinal nerves leaving IV foramina
Arteries supplying the spinal cord 1) 2) 3)
1) Posterior intercostals 2) Lumbar arteries 3) Lateral sacral
Venous system that drains the spinal cord
External vertebral venous plexus
Growth of spinal cord relative to growth of body
During development, body grows faster than spine. Therefore, spinal cord terminates at L1/L2 in adults, but lower down in children
Why does herniation of IV disc affect nerve exiting foramen lower than the site of herniation?
Epidural anaesthesia
Giving injection of anaesthetic extra-durally in lumbar spine
