Spine/Back Flashcards
How many vertebra and spinal nerves are there?
C7 - 8 nerves
T12 - 12 nerves
L5 - 5 nerves
S5 - 5 nerves
C4 - 1 nerve
~33 bones in total & 31 pairs of spinal nerves
What are the functions of the spine?
- Protection of spinal cord
- Movement
- Axis
- Supports
What are the key features of a vertebral body?
- Body (gets larger the lower down the spine) lined by hyaline cartilage superiorly/inferiorly
- Seperated by cartilaginous IVD
- Vertebral arch
- Vertebral foramen
- Spinous processes
- Transverse processes
- Pedicles (body to transverse process)
- Lamina (connects spinous & transverse process)
- Articular processes to connect to sup/inf vertebral bodies
Explain the anatomy of the IVD. How do they prolapse?
Secondary fibrocartilaginous joint
Inner nucleus pulposus and outer annular fibrosus
Movements: FL/EX, lateral FL & axial rotation
Herniates postero-laterally due to decrease in size of post. longitudinal ligament in lower back causing irritation to lower spinal root - a central prolapse will cause cauda equina
How do the cervical vertebra differ?
Short bifid spinous process EXCEPT:
C1 has no spinous process
C2 is very thick
C7s is very long and may not bifurcate
So cannot be felt as attached to nuchal ligament
Transverse foramina for vertebral artery (below C6 and at C7 it is smaller for vein as the artery comes in at C6)
Triangular vertebral foramen
Specialised:
C1 (atlas): no body, allows flexion of head so facet for occipital condyle
C2 (axis): body forms odontoid peg/dens for rotation of head + facet for attachment to alar ligament
How do the thoracic vertebra differ?
2 demi-facets on each superiorly/inferiorly of vertebral bodies to articulate with head of ribs
Costal facet on transverse processes for articulation with rib shaft
Spinous processes are postero-inferiorly directed
Circular vertebral foramen
For example, the head of Rib 2 articulates with the inferior demi facet of T1 and the superior demi facet of T2, while the shaft of Rib 2 articulates with the costal facets of T2
How do the lumbar vertebra differ?
Large kidney shaped vertebral bodies
Triangular shaped vertebral foramen
Shorter spinous processes and do not extend inferiorly
How do sacrum and coccyx differ?
Fused vertebrae
Sacrum is formed of 5 and is an inverted triangle with facets for articulation with ilium at SIJ either side
Coccyx is formed of 4 and is small articulating with apex of sacrum with absent vertebral canal & arches
What are the joints & ligaments of the vertebral column?
Joints:
1. Superior articular facets: articulate with vertebra above
2. Inferior articular facets: articulate with vertebra below
3. IVD: vertebral body articulation
4. Atlano-axial joint: synovial pivot
Ligaments:
1. Ant. longitudinal: prevents hyperextension
2. Post. longitudinal: prevents hyperflexion -> tectorial membrane at top
3. Ligamentum flavum: between lamina
4. Interspinous: join spinous processes
5. Supraspinous: join tips of spinous processes
6. Transverse ligament: between transverse processes
7. Alar ligaments, transverse atlantal & apical odontoid all attach to odontoid at superior end
What level does the spinal cord terminate? Where do you perform LP and what are the layers?
L2 in adults forming fcauda equina (L2-S5) conus medullaris (S1-5) then filum terminale
L3 in children
Dural sac ends at S2
LP @ supracristal plane (L4-5) going through skin, subcut fat, fascia, supraspinous ligament, interspinous, ligamentum flavum, epidural space, dura, subdural space, arachnoid mater & subarachnoid space w/ CSF
What are the 2 enlargements of the spinal cord?
Cervical = C4-T1 where brachial plexus starts
Lumbar = T11-L1 where lumbosacral plexus arises
What is the anatomy of the spinal nerves?
Mixed nerves forming PNS
Begin as anterior (motor) root and posterior (sensory) root uniting at intervertebral foramina to form a single nerve
Leaves the vertebral canal and splits into posterior and anterior rami to supply back and then everything else respectively
What is the blood supply & venous drainage to the spinal cord?
1x anterior spinal artery
2x posterior spinal artery
(From vertebral arteries)
Small ant/post segmental medullary arteries entering via nerve roots - largest is artery of Adamkiewicz supplying inferior 2/3rd of cord (inf. intercostal/upper lumbar arteries)
Venous drainage is via radicular veins -> 3x anterior spinal and 3x posterior spinal veins -> internal ant/post vertebral plexuses (run length ant/post to dura)* -> DVCs (internal) + systemic segmental veins
*note external plexuses anterior one is small system around body whereas posterior is extensive system around processes
Please briefly describe the anatomy of the muscles of the back.
Superficial layer: shoulder movements
1. Trapezius: from skull, ligamentum nuchae & spinous processes of C7-T12 attaching to clavicle, acromion & scapula spine (CNXI) - elevates scapula + rotates it during abduction
2. Lat dorsi: from spinous process T6-T12 , thoracolumbar fascia, iliac crest & inferior 3 ribs to intertubercular groove of humerus (thoracodorsal n) - extends/adducts + MR of UL
3. Levator scapulae: transverse process of C1-4 to medial scapula border (dorsal scapular n) - scapula elevation
4. Rhomboids major: spinous process T2-5 to medial scapula border (dorsal scapular n) - retracts/rotates scapula
5. Rhomboid minor: from spinous processes C7-T1 attaching to medial scapula border (dorsal scapular n) - retractes/rotates scapula
Intermediate: thoracic cage movements (intercostal nerves)
1. Serratus posterior superior: inferolateral direction of fibres elevating ribs 2-5
2. Serratus posterior inferior: superolateral direction of fibres depressing ribs 9-12
Deep/intrinsic: vertebral column movements
1. Superficial (spinotransversales): splenius capitis (post. rami of C3-4) & cervicis (post. rami of lower C nerves) - rotate head/EX if BL
2. Intermediate/erector spinae: iliocostalis, longissimus & spinalis - arise from lower T/L vertebra, sacrum, post. illiac crest & sacroilliac/supraspinous ligaments causing lat. flexion or extension if BL (post. rami of spinal nerves)
3. Deep (transversospinales): semispinalis, multifidus & rotatores (post. rami of spinal nerves)
=~12
What structures pass through intervertebral foramen?
- Root of each spinal nerve
- Dorsal root ganglion
- Spinal artery of segmental a
- Communicating veins between internal/external plexuses
- Recurrent meningeal nerves
- Transforaminal ligaments
What does the scottie dog represent?
Nose = transverse process
Ear = superior articular process
Eye = pedicle
Neck = pars interarticularis (incomplete in spondylolysis = stress #)
Whats in the epidural space?
Lymphatics
Spinal nerve roots
Loose connective tissue & fatty tissue
Small arteries
Internal vertebral venous plexus
What tumours metastasize to the spine and via what route?
Breast, lung, thyroid, kidney & prostate
Routes:
1. If primary via arterial system
2. Retrograde through batsons plexus: valveless vein network connecting deep pelvic veins draining bladder, prostate + rectum to internal vertebral venous plexus
3. Direct invasion through intervertebral foramina
What structures are found at C6?
Arch of cricoid (laryngeal prominence @ C4-5)
Vertebral artery enters transversarium foramen
Termination of pharynx + beginning of oesophagus
Termination of larynx & beginning of trachea
Middle thyroid VEIN emerging from thyroid gland
Inferior thyroid ARTERY entering thyroid gland
Intermediate tendon of omohyoid crosses carotid sheath
What happens at C3-4?
Hyoid bone @ C3
CCA bifurcation @ upper margin of thyroid cartilage
What are the different spinal tracts?
Ascending:
1. Dorsal column (FC UL & FG LL): fine touch, vibration & proprioception made up of 1st order (synapse in medulla where they decussate), 2nd order (synapse in thalamus) & third order neurons (to primary sensory cortex)
2. Ant. spinal thalamic: crude touch & pressure - travel same pathway but decussate 1-2 levels above entering spinal cord
3. Lat. spinal thalamic: pain/temp - “””” pain is sensed via free nerve endings in skin (C fibres = dull ache & A-delta fibres = fast/sharp)
4. Spinocerebellar: unconscious proprioception - all stay ipsilateral
Descending:
Pyramidal tracts
1. Corticospinal: muscles of body - begin in cortex (UMN) and descend via IC of BG -> lateral tract decussates in medulla but ant. tract decussates + terminate in cervical/upper thoracic segments - LMN once exit spinal cord
2. Corticobulbar: head/neck muscles B/L innervation except for CNVII (contralateral on lower 1/2 of face) & CNXII (contralteral)
Extra-pyramidal tracts
3. Vestibulospinal: balance/posture remaining ipsilateral
4. Reticulospinal: voluntary movement + muscle tone
5. Rubrospinal: C/L innervation of fine hand movements
6. Tectospinal: decussate in midbrain & control head movements w/ relation to visual stimuli
What is the difference between a UMN and LMN?
UMN: hypertonia, hyper-reflexia, clonus, babinski sign (extension of toe) + spastic paralysis/weakness e.g. CVA
LMN: hypotonia, hypo-reflexia, fasciculations & flaccid paralysis/weakness e.g. cauda equina or bells palsy
Briefly describe the ANS.
PS = rest/digest
Components:
1. Pre-ganglionic: long, myelinated & release ACh - exit CNS either at CN nuclei in brainstem III , VII , IX & X or sacral spinal nerves S2-4 (form pelvis sphlanchnic nerves)
2. Peripheral ganglia: neuronal cell bodies where synapse occurs close to structure they innervate - ciliary, SM, pterygopalatine & otic
3. Post-ganglionic fibres to effector organs: short, unmyelinated & release ACh
Sympathetic = flight/fight
Components:
1. Pre-ganglionic neurons: originate in thoracic/lumbar segments of spinal cord & are short, unmyelinated + release ACh -> exit cord via ant. spinal nerves passing through white ramus communicans to enter sympathetic trunk where they may:
- Synapse with post-ganglionic neurons at this level
- Ascend/descend within chain to synapse at other level
- Pass through chain w/o synapsing (later will synapse at prevertebral ganglion or adrenal medulla = sphlanchnic nerves)
2. Peripheral ganglia: sympathetic chain either side of vertebral column or prevertebral ganglia around major abdominal aorta branches coeliac, SMA + IMA
- Sympathetic chain = 22 pairs of interconnected cell bodies from skull base to coccyx -> Cx3 (sup/mid/inf), 11-12T, 4L, 5S & 1C
- Prevertebral ganglia supplied by sphlanchnic nerves - coeliac (T5-9 via greater sphlanchnic n), SMA (T10-11 via lesser sphlanchnic n) & IMA (T12 via least sphlanhnic n)
- Adrenal medulla: modified sympathetic ganglion with fibres synapsing directly here to allow it to secrete A/NA
3. Post-ganglionic fibres: long & unmyelinated releasing NA travelling to target via named nerves with blood vessels or within autonomic plexi
What are the common organisms causing osteomyelitis? What is the most common causes?
S. Aureus
Enterobacter species
GAS
Salmonella is pathognomic in SCD patients
Causes:
In adults its mostly exogenous so acutely from # or iatrogenic disruption to bone or chronic from neglected wounds in diabetes/ulcers
In children it is more likely haematogenous spread from sepsis & due to their immature immune systems
If adult is haematogenous then the vertebra is most commonly affected
What are the common locations of osteomyelitis?
Paediatrics (boys>girls)
- Metaphysis/epiphysis of long bones
- Lower extremity > upper
Adults:
- Long bones
- Vertebra if immunocompromised e.g. elderly or transplant patients
- In IVDUs medial/lateral clavicle
- In dialysis patients rib/spine
How is osteomyelitis classified?
Cierney-mader classification: takes into account anatomical involvement, host, treatment & prognosis
Anatomic location
Stage 1: medullary
Stage 2: superficial
Stage 3: localised
Stage 4: diffuse
Host type
A = normal
B = compromised
C = Tx is worse than infection
Define abscess & pus.
A localised painful collection of pus in a tissue enclosed in granulation tissue usually due to an infection - they can undergo:
1. Resolution
2. Rupture
3. Spread -> sepsis
4. Chronic abscess
Pus = thick yellow liquid that is formed by a inflammatory response to infection consisting exudate mainly containing dead neutrophils, tissue debris & pathogenic microorganisms - it occurs because microbial invasion causes acute inflammation with vascular congestion, exudate & infiltrate of PMNs
What is the pathogenesis of osteomyelitis?
- Invasion & inflammation of bacteria due to
- Suppuration + abscess formation
- Necrosis + sequestration/involucrum
- Brodie abscess may form if abscess walled off by fibrosis/bone sclerosis -> subacute osteomyelitis where there is residual acute osteomyelitis versus haematogenous seeding of growth plate trauma
- Sinus may also form to skin due to increases IO pressure due to increased osmolarity from tissue breakdown or a large cloacal opening forming in the involucrum - New bone formation
- Resolution
Sequestration = dead bone has become seperated from normal bone via necrosis
Involucrum = reactive woven/lamellar bone depositions form shell of living tissue around sequestrum
How to treat osteomyelitis?
Conservative
- Supportive for pain/dehydration
- Splintage of limb
Medical
- BCs + high dose IV Abx is mainstay e.g. co-amox or cephalosporins
Surgical
- Remove any plates as they are a septic focus, will form biofilm and be less sensitive to abx & it might be loose
- Surgical drainage if no response in 2/7
Why would SCC develop in osteomyelitis sinus tract?
Chronic irritation -> hyperplasia -> dysplasia -> carcinoma
What protein deposited in chronic osteomyelitis?
Amyloid AA
What are the DDx of a swollen knee? How would you investigate?
Septic arthritis
Gout
Pseudogout
Tumours
Trauma
Single bedside test = aspiration for gram stain, cytology, chemical analysis, crystals & MC+S
Please differentiate gout and pseudogout. How do you manage them?
Gout
Monosodium urate crystal
Negatively birefringent needle shaped crystals
1st MTPJ most commonly affected (podagra)
Rat bite erosions on radiography
Pseudogout
Calcium pyrophosphate crystals
Positively birefringent rhomboid shaped crystals
Commonly affects knee
Chrondrocalcinosis
Mx of both = NSAIDs
What is a pathological # and what are some causes?
Bone fracture occurring without adequate trauma due to pre-existing pathological bone lesion/disease
Causes:
Neoplastic: primary tumour (multiple myeloma) or mets
Non-neoplastic: osteomytelitis, osteoporosis & pagets
What are other sites of ectopic thyroid tissue other than head, neck & thorax?
Ovarian
Testicular teratoma
How would you manage this patient if you were suspicious of malignancy?
ATLS primary and secondary survey
1. Fix #
2. Bone biopsy
3. If thought to be from thyroid, can do radioactive isotope scan (medullary cancer wont show up as its from parafollicular C cells)
What tests do you need to do before transfusing a patient? What can happen if incompatible blood is given?
G+S to do a blood group and Ab screen
ABO
Rh group cross matching to see if receipient has preformed Abs against Ags on donor cells that may cause haemolysis
If incompatible blood is given:
- Acute haemolytic reaction
- Febrile non haemolytic reaction
- Delayed haemolytic transfusion reaction
- TRALI
Haemolysis = rupture of RBCs + release of contents into cytoplasm into surrounding fluid
What is DIC?
Pathological consumptive coagulopathy due to activation of coagulation + fibrinolytic systems -> microthrombi which consumes clotting factors + platelets causing concurrent haemorrhage
Characterised by
1. Thrombocytopaenia
2. Decreased fibrinogen
3. Increased FDPs
What is the precursor and function of platelets?
Start from megakaryocytes
1. Adhesive/cohesive function
2. Activates coagulation
= haemostatic plug
Briefly explain the coagulation pathways.
Endothelium is damaged, so platelets adhere to subendothelial collagen releasing thromboxane A2/5-HT to aggregate into platelet plug (primary haemostasis)
Secondary haemostasis occurs via three integrated pathways:
1. Intrinsic (APTT): activated by vessel injury leading to activation of CNXII which subsequently activates FXI, FXI then FX
2. Extrinsic (PT): activated by tissue thromboplastin released by damaged cells which activates TF (FIII) which combines with FVII + directly activated FX (3+7 = 10)
3. Common pathway (PT): factor X is activated which cleaves prothrombin to thrombin (FIIa) which converts fibrinogen to fibrin (FIa) -> monomers are joined by FXIIIa to form fibrin mesh/stable clot
Please describe the gell & coombs hypersensitivity classification.
ACID-EGGT
Type 1 (anaphylactic): IgE mediator via exogenous Ag occuring over minutes e.g. asthma/hayfever
Type 2 (cytotoxic): IgG mediator via cell surface Ag occuring over hours e.g. goodpastures
Type 3 (immune complex): IgG mediated via soluble Ag occurring over hours e.g. SLE
Type 4 (delayed): T cell mediator to tissue Ag occuring over 2-3 days e.g. GvHD + contact dermatitis
What is the percentage of WBCs in packed RBCs?
<5x10^6 (leukoreduced packed RBCs)
What are the stages of bone healing after a fracture?
- Haematoma formation where site will swell, cause pain, inflammation & necrosis
- Fibrocartilaginous callus develops over 3-4 weeks to splint # via capillary growth into haematoma, phagocytic cells invading/clearing up debris & fibroblast/osteoblast migration to begin reconstruction
- Bony callus begins forming and is prominent 2-3 months post-injury via continual migration/multiplying of osteoblasts/osteocytes
- Remodelling via excess bony callus removal + compact bone laid done to reconstruct shaft
Prolonged immobility may cause loss of bone density + increased osteoporosis
What is PVL S. Aureus?
B pore-forming cytotoxin produced by S. Aureus often MRSA causing leukocyte destruction and tissue necrosis = increased virulence as pores in membrane of infected cells are formed and necrotic lesions formed involving skin & mucosa including necrotic haemorrhagic pneumonia
How would you assess someone with polytrauma concerning the C spine?
ATLS
- Airway - look (accessory muscles/foreign bodies/injuries), listen (stridor/gurgling/wheeze) + feel (chest wall movements + airflow @ nose/mouth)
May need simple manouvres, adjuncts or intubation/surgical airway
- C-spine control with neck collar, sandbag + tape plus spinal board immobilisation
- Breathing - look (resp distress), listen (airway obstruction/compromise) & feel (air/fluid via percussion)
If concerned for open pneumothorax 3-way occlusive dressing followed by tube thoracostomy is performed (if air column not moving look for improper placement or blockaged)
- Cardiovascular: conciousness, skin perfusion & pulse - bleeding control, large bore BL access, IVF/blood/phlebs/gas, catheter + IP/OP
- Disability: AVPU, PEARL, BMs + temp - look for focal neurological defect
- Exposure + log roll (4 people): abdo exam + pelvic binder
What is shock? How is it classified?
Cellular/tissue hypoxia due to reduced oxygen delivery/increased oxygen consumption/inadequate utilization
- Distributive e.g. septic, neurogenic, anaphylactic
- Cardiogenic
- Hypovolaemic
- Obstructive e.g. PE
How to differentiate spinal vs neurogenic shock? What agents can you give?
Spinal shock is immediate loss of power/sensation/reflexes below level of injury due to unresponsive peripheral neurons whereas neurogenic is sudden loss of sympathetic tone causing vasodilation, hypotension & bradycardia
Both will present with hypotension + bradycardia 48-72 hours after SCI
The bulbocavernosus reflex (S2-4) may be absent in shock and is one of the first things to return (reflex contraction of EAS with glans/clit stimuli/pulling on catheter)
Vasopressors used: phenylephrine, dopamine or norepinephrine
Please explain the different spinal cord syndromes.
- Central cord: motor loss UL > LL with varying sensory loss after hyperextension injury in patient with pre-existing cervical canal stenosis - recovery possible
- Anterior cord: paraplegia + B/L loss of pain/temp with intact sensation due to ischaemic damage - poorest prognosis
- Brown sequard/hemisection: ipsilateral motor loss (CST), loss of position sense (DC - test w/ tuning fork) + C/L pain/temp loss 1-2 levels below injury (STT - test w/ pinprick) due to penetrating trauma - some recovery possible
How do you perform a spine exam?
WIPE
1. Inspect from front, side and back + also inspect gait + inspect pushing against wall for serratus anterior winging - scars, wasting, symmetry, lordosis/kyphosis/scoliosis + posture
2. Feel down vertebral bodies spinous processes, paraspinal muscles + SIJs
3. Movements of each segment of spine:
- Cervical - FL/EX, L/R & lateral flexion
- Thoracic - ask patient to sit with arms crossed and rotate
- Lumbar - lateral flexion & FL/EX
4. Special tests
- SLR - raise patients leg and when they experience pain (30-70 degree pain indicates radicular pain/lumbar nerve root irritation/sciatica), then decrease angle until pain gone then dorsiflex foot + this should cause pain again
- Femoral stretch test - prone patient + flex knee to 90 degree then lift thigh off bed to extend hip = pain means L2-4 compression
- Offer Schobers for AS - find PSIS then go to midline (dimples of venus) measure 5cm down and 10cm up then ask patient to bend forward and overall distance should be >20cm now when measured
How to perform a peripheral LL neurological exam?
ATP RCP
WIPE
1. End of bed inspection
2. Inspect for scars, wasting & fasiculations - if LL get them to walk
3. Assess tone by rolling limb around when relaxed - leg roll/lift & ankle clonus (<3 is normal)
4. Assess power by asking patient to resist all movements:
- Hip flexion (L2)
- Knee extension (L3)
- Ankle dorsiflexion (L4)
- Plantarflexion (S1)
- Big toe extension (L5)
5. Reflexes: knee jerk (L3-4) & ankle (L5-S1)
6. Coordination: heel to shin test
7. Sensation of dermatomes w/ light touch + pin prick: medial thigh (L1), lateral thigh (L2), medial knee (L3), medial malleolus (L4), big toe (L5), little toe (S1) & posterolateral thigh (s2)
What are some other differentials for disc herniation? How would you investigate and manage?
DDx: spinal canal stenosis, vit B12 deficiency, DM (peripheral neuropathy) & tabes dorsalis
Ix: X-ray & MRI lumbo-sacral spine
Mx: conservative with physio/analgesia, epidural steroid injection for stenosis or surgical with discectomy/laminectomy if disc prolapse or decompressive surgery if spinal stenosis
If a patient has an epidural and becomes unstable after what are you differentials? How would you manage?
DDx: high block*, distributive shock, paralysis of ICs/diaphragm or post-op hypovolaemia
*bradycardia will develop due to blockade of sympathetic cardioaccelerator fibres from T1-5 causing unopposed PS innervation of CNX + peripheries will be warm/pink due to vasodilatation (this would be opposite in hypovolaemia)
Mx w/e A-E as per CCRISP:
- Sit patient upright and stop epidural
- 100% O2
- R/o concomitant shock
- Call surgeon/anaesthetics
- May need to consider inotropes e.g. metaraminol & chronotropes e.g. atropine
What factors affect epidural efficiency? Why would you chose to do one instead of GA?
Better if surgery is longer, for post-op analgesia & because it improves outcomes
Factors affecting efficiency: level, dosage, patient positioning & type of medication
What levels are used for different surgeries and how can you test the level of the block?
T4 = upper abdo
T6 = intestinal/gynae/uro
T10 = vaginal/hip
L1 = thigh/lower leg
L2 = foot/ankle
S2-5 = perineal/anal
Test block with temperature sensation e.g. ice packs or ethyl chloride spray because motor fibres last to be affected but pin prick not advised due to bleeding/infection risk
What are the systemic effects of epidurals?
Hypotension due to sympathetic outflow block + vasodilation
Reduced CO due to venous return reduction
Reduction of FRC
Attenuates surgical stress response
What ligaments stabilise atlanto-axial joint?
Ant/post atlantoaxial ligaments
Transverse ligaments
+ normal ligaments of the spine too
What is the commonest level of cervical spine fracture? What other imaging may need to be done?
C5
Angiogram to assess for damage to carotid and vertebral arteries
What is autonomic dysreflexia?
Autonomic dysregulation to insult often above T6 -> sympathetic response below level of injury and PS response above
Life-threatening complications include CVA, seizures, arrythmias & cardiac arrest
