Session 2: Spinal Cord Flashcards
15.10.2019
What are the functions of the vertebral column?
Support and Protection
- Body weight
- Transmits forces
- Supports the head
- Supports the upper limbs (and aid movements)
- Spinal cord
Movement
- upper limbs + ribs (extrinsic muscles)
- postural control and movement (intrinsic muscles)
What are the regions. of the vertebral column?
C1-C7 T1-T12 L1-L5 S1-S5 (sacrum) Coccyx
What are the curvatures of the spine?
There are 4:
- cervical (secondary)
- thoracic (primary)
- lumbar (secondary)
- sacral (primary)
What are primary and secondary curvatures?
Primary: same as in the foetus with the concavity facing anteriorly
Secondary: concavity facing posterior, develops with upright stance
How does posture change in pregnancy?
As the baby grows, women start to lean back to counteract the weight of the baby anteriorly.
=> also applies to obese people. (secondary curvature to make the center of weight correct)
Where is the lordotic curvature in humans?
in the lumbar spine
the curvature is extensive in four legged animals when mating
Does lordosis, mean there is something wrong with them?
No, only if the lordosis is exaggerated.
What is a potential cause of scoliosis?
- hormonal influence
- e.g. females during puberty
What are the problems associated with scoliosis?
- aesthetics
- organs in the chest/abdomen can be compressed with extensive curvature
- severe, chronic pain
How can severe scoliosis be treated?
- surgery which involves screws in the vertebral column
- adjusting the screws and rods so that the column becomes upright
How can less severe scoliosis be treated?
- brace
- corsett
-> helps straighten the vertebral column
What are the bones of the back?
33 vertebrae
- 7 cervical
- 12 thoracic
- 5 lumbar
- 5 sacral (fused)
- 3-4 coccygeal (fused)
What allows flexibility of the back?
- the stacking of units
- each vertebrae by itself is not flexible, only when they are stacked
What percentage of people is hypermobile?
~ 20%
=> means you can bend joints more than others and are flexible
What are the main components of a vertebra?
- vertebral body (weight bearing part)
- vertebral arch (spinal cord passes in the middle)
- pedicles (anchor the body to the arch)
What determines how a spine fragment can move?
- appreciate that the orientation of the facets determines how you can move the spine:
- vertical: difficult to move sideways, forwards + backwards works well
- horizontal: more rotation is possible
Vertebral arch
- Forms roof of vertebral canal
- Has projections for attachment of muscles and ligaments
- Has sites of articulation for adjacent vertebrae
Vertebral body
- weight bearing part of the vertebrae
Pedicles
- Anchor the vertebral arch to the vertebral body
Intervertebral disks
- are situated in between vertebrae
- water filled structures that have some cartilage collagen rings in the middle with a gel nucleus
- help transmit forces
- throughout the day the disks become dehydrated -> shorter
What is the issue with degenerative disease of the intervertebral disks?
- if the gaps between vertebrae become smaller they can impinge on nerves
- intervertebral foramina may become smaller and cause problems like pain due to pressing on nerves
Which vertebrae are atypical?
C1 and C2
-> allow for movement of head and neck, great deal of flexibility
When are injuries to C1 and C2 common?
- in car accidents, the seatbelts do not protect the head and these vertebrae
- this area is put under extreme stress
- damage can cause paralysis from neck down or death
What is special about the C1 vertebra?
- “atlas”
- the vertebral body is not connected, it is connected to the vertebrae beneath
- holds the head
- if the neck undergoes extreme flexion or extension, odontoid peg can break loose and crush the spinal cord or lower part of medulla -> instant death (hanging)
What causes fast death in high speed collisions or in hanging?
if the neck undergoes extreme flexion or extension, odontoid peg can break loose and crush the spinal cord or lower part of medulla -> instant death
Why do only cervical vertebrae have transverse foramina?
It is where the vertebral arteries pass, therefore only needed there.
What lies on the body of C2?
- the odontoid peg
- it is the body of C1 which is joined to C2
- allows for rotation of C1 and C2 -> specific range of motion
How can you distinguish cervical vertebrae?
- they have transverse foramina
How can you distinguish thoracic vertebrae?
- they have heart shaped bodies
- ribs attach to them
How can you distinguish lumbar vertebrae?
- they have kidney shaped bodies
What are the alar ligaments
- come from the underside of the skull
- cross to the odontoid peg.
What is the cruciate ligament?
- collective term for ligaments from skull to C2
- cruciate = cross
Atlanto-axial joint
- between C1 and C2
- NO joint (allows rotation)
- principal joint that allows rotation
Atlanto-occipital joint
- between skull and C1
- YES joint (allows nodding of head)
- skull can rock backwards and forwards on this joint
- principal joint that allows flexion and extension
What are the tough ligaments that run along the vertebral column called?
anterior and posterior longitudinal ligaments
Ligamenta flava
- found between adjacent laminae
Interspinous ligaments
- between spinous processes (?)
Which ligaments should you know?
- longitudinal ligaments (A and P)
- supraspinous ligament (tough)
- interspinous ligaments (limit how much you can bend down towards the floor
- ligamentum flavus (yellow ligament; between laminae)
=> huge stability + allow for movement
Where do spinal nerves emerge from?
Intervertebral foramina
Where do spinal nerves emerge from in relation to the vertebrae? (height)
- C1-C7 emerge above the vertebrae
- C8-coccygeal emerge below the vertebrae
=> because we have a C8 nerve but no C8 vertebrae
Below which level is there no more spinal cord present?
below L2
Corda equina
- “horses tail”
- bundle of nerves where the spinal cord has finished
- where injections are given like spinal anaesthetic
- where CSF can be take taken in an LP
Prolapsed intervertebral disk
- ruptured disk, contents emerge into the space that is occupied by the nerves or the spinal cord
- jelly like substance takes the path of least resistance out
- pain, parasthesia, weakness
What is parasthesia?
is an abnormal dermal sensation (e.g., a tingling, pricking, chilling, burning, or numb sensation on the skin) with no apparent physical cause
What part of the spine do disk herniations usually occur at?
- lower spine
- reason: the lower spine has to bear more weight
What can the oblique muscles facilitate?
- help with side bending and rotation
What can the erector spinae muscles do?
- make the spine straight
- very complicated intrinsic muscles of the spine
What are intrinsic and extrinsic muscles of the spine?
Intrinsic: the deep muscles develop embryologically in the back
Exrtinsic: The superficial and intermediate muscles do not develop in the back
What meningeal layer is not present in the spine?
- the periosteal dura reflects back at the foramen magnum
- there is an epidural space in the vertebral column but not in the brain
sacral hiatus
- hole at the end of the spine
Common spinal pathology
- Low back pain
- Prolapsed intervertebral disc - sciatica
- Spondolysis (degeneration)
- Spondylolysis (stress fracture of pars interarticularis)
- Spondylolisthesis (forward displacement of vertebra)
- Spondylitis (inflammation of vertebrae)
What is the difference between spinal and epidural anaesthesia?
Spinal:
- e.g. C-section or hip replacement if patient is not fit for GA -> known length of procedure, limited space for drug.
- inside subarachnoid space
Epidural:
- e.g. duration of about (unknown), can be infused, large convenient space
- around the dura
Spinal injuries
- Spinal cord injury paralyses over 6 people every day
NHS Specialised Spinal Cord Injury Services Annual Statement - in 2017/18, 2429 new patients were referred to the eight specialist centres in England. - This adds to the 50,000 living here that are already paralysed.
- Most common causes of spinal cord injury is a broken neck or back as a result of road traffic accidents, accidents during sports or recreation or falls (in older people).
- Currently no cure – yet!
