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Anatomy of Spinal Cord

  1. Vertebral column consist of 33 vertebrae: 7 cervical 12 thoracic 5 lumbar 5 sacral 4 coccygeal Spinal segments
  2. Spinal nerves are 31 in no.: 8 cervical 12 thoracic 5 lumbar, 5 sacral & 1 coccygeal
  3. Vertebral column has 4 curves, thoracic & sacral are convex are concave posteriorly.
  1. Spinal cord.
    1. Occupies the whole vertebral column in intrauterine life but in infancy it ends at lower border of L3 while in adults it extends upto lower border or L1 (or upper border of L2 at times)
    2. Dura extends up to S2
    3. Pia (As filum terminale) up to coccyx
    4. Layers: it is covered by 3 layers from outside --> inside; Dura --> Arachnoid --> pia
    5. CSF is present in subarachnoid space
    6. Blood supply by 2 posterior spinal (branches of posterior, inferior cerebellar) & one anterior spinal A. (formed by a branch from each vertebral artery)
    7. Extradural veins - these are valveless veins extending from cranium (intracranial sinuses) to pelvis
  2. Imp. surface landmarks
    1. C7 is very prominent & easily palpable
    2. T7  lies opposite to inferior angle of scapula
    3. Highest point on iliac crest corresponds L4-5 inter - space
    4. Nipples corresponds to T4
    5. Xiphisternum to T6
    6. Umbilicus to T10
    7. Inguinal ligament to L1
  3. Segmental level of spinal reflexes
1 Epigastric T7 & T8
2 Abdominal T9 - T12
3 Cremasteric L1, L2
4 Knee jerk L2 3 4
5 Ankle jerk S1 S2
6 Anal sphincter S4-5
8 Plantars S1,   L5

  1. Absolute  contraindication of central neuraxial blockade (AIPG 07)
    1. Raised ICP
    2. Coagulopathy
    3. infection at the site needle insertion
    4. patient refusal
    5. severe hypovolemia
    6. severe Mitral stenosis and Aortic stenosis

Spinal Anaesthesia

  1. Excellent for
    1. Orthopedic surgery of lower limbs & pelvis
    2. Gynaecology & obstretical surgeries
    3. Hernias, hydroceles,  other lower abdominal surgeries
    4. Perineal surgeries
  2. It can be performed in
    1. Lateral position                         
    2. Sitting position
    3. Prone position (Not Common )
  3. Approach may be midline or paramedian
  4. Type of Spinal needles      
    1. Quinkeback’s                             
    2. whiteacre
    3. sporette                                      
    4. Pencil tip point end
  5. Structural encountered during spinal anesthesia
    1. Skin                                                          
    2. Subcutaneous tissue
    3. Supraspinous ligament                       
    4. Interspinous ligament
    5. Ligamen flavum                        
    6. Dura
    7. Arachnoid
  6. Drugs
    1. Xylocaine (Lignocaine) 5% Heavy i.e. Hyperbaric i.e. SG> CSF (1004)
      It is made heavy by addition of Dextrose 7.5%
    2. Tetracaine 0.5% in 5% Dextrose (not available in India)
    3. Bupivacaine 0.5% in 8% Dextrose
  7. Factors effecting height of block
    1. Dose (most imp. factor)

      NOTE: Intubation is not required in spinal anaesthesia

    2. Baricity of solution.
    3. Volume of drug (this ­es the dose)
    4. barbotage
    5. Direction of needle
    6. Added vasoconstrictor (No role in hyperbaric solution)
It is rather C/I because can cause cord ischemia in spinal
  1. Systemic effects of spinal anaesthesia
    1. CVS –
      1. Sympathetic block cause HYPOTENSION, bradycardia (if block is high enough to block cardioaccelator fibres T1 - T4)
        →↓ Venous return → atrial pressure  Bradycardia [Bainbridge reflex]
      2. In individual hypotension causes tachycardia (Marey’s law)
    2. Other causes of hypotension are:
      1. Venous return (because of dilation of veins)
      2. Bradycardia - Cardiac output
      3. Blockage of adrenal glands sym. supply catecholamines
      4. Direct absorption of drug in systemic circulation
    3. CNS
      1. Autonomic level is 2 segments higher than sensory which is 2 segments higher than motor
    4. Resp.
      1. only very high block effect respiration.
    5. Causes of Apnea are
      1. Hypotension severe enough to cause medullary ischemia
      2. High spinal (to block even phrenic C3 4 5
      3. Total spinal
      4. Intravascular injection
        Rx - IPPV or intubation is required treat hypotension
        IV. G.I.T sympathetic block causes parasympathetic / predominance so Decrease peristalsis & Increases sphincters tone
    6. High incidence of nausea & vomiting reasons are
      1. Hypotension central hypoxia N & V
      2. Abdominal structure handling
      3. Due to bile in stomach (relaxed pyloric sphincter)
      4. Psychological
      5. Stress response: blocked by spinal
      6. Temp.: vasodilatation causes heat loss  shivering
      7. G.U. System: ­ urinary retention
      8. Flaccid penis (paralysis of nervi ergentis) & engorged
  2. Complication of spinal Anaesthesia
    1. During surgery
      1. Hypotension --> most common complication
        Rx prophylactic --> preloading with 1-1.5 L of fluids   
        1. Infusion of fluids
        2. Vasopressors - ephedrine 2-6 mg (DOC for post spinal hypotension in pregnancy)
          • mephenteramine
          • Dopamine (if not controlled)
      2. Bradycardia
        Rx - Atropine, Isoprenaline (If not controlled )
      3. High spinal --> complications depends on level if up to block cardioaccelrator fibres then Bradycardia & hypotension if involves cervical Diaphragmatic paralysis occur
        Rx IPPV through E.T.T
      4. Resp. Paralysis (Apnea)
      5. Nausea & vomiting
        Rx - oxygenation
        Correct hypotension
        Metoclorpamide (If not C/I) or Ondansetron
      6. Apprehension & anxiety
        Rx:- sedate the patient     
    2. Total SPINAL BLOCK
      1. A total spinal block is a rare and very serious complication that occurs after excessive cephalad spread of the local anesthetic. It can occur during single-shot spinal anesthesia or as a result of inadvertent intrathecal spread of epidural medication after unintentional dural puncture or catheter migration. Subdural spread of the local anesthetic can also cause a high block characterized by a high sensory level, sacral sparing, and incomplete or absent motor block. Single-shot spinal anesthesia after a failed spinal or patchy epidural may also precipitate a total spinal. 
      2. There are several possible mechanisms for high spinal blocks when a spinal is attempted after failed epidurals. Expansion of the epidural space may compress the spinal canal and encourage cephalad spread of intrathecal drugs. Rapid transfer of local anesthetic from the epidural space across the dural hole may also occur. In addition, sufficient local anesthetic may be present in the nerve roots to decrease the dose requirements of subsequent spinal anesthesia. 
      3. In the case of a nonemergency cesarean section when a patchy block is present, several options are possible without resorting to a single-shot spinal. An epidural catheter can be relocated and the drug titrated through the catheter. Alternatively, a CSE can be placed in which a fraction of the usual spinal dose can be administered; again, the catheter can be used to titrate to a desired level. Other options include repeating a spinal after waiting for the original block to resolve or converting to a general anesthetic.
      4. Factors Affecting Block Height
        Unlike epidural dose requirements, weight is not related to block height during spinal anesthesia. Patient height is related, although the contribution is minor compared with more important factors. Age, injection rate and barbotage of isobaric and hyperbaric solutions have not been shown to affect block height, although injection rates in these studies have been above 0.1 to 0.2 mL/sec.] It is becoming clear that the direction of spinal needle lateral-facing openings affect block height levels, even with isobaric spinal solutions.]
      5. Other maneuvers that do not appear to affect block height are coughing and straining after local anesthetic injection. This is related to the physics of injecting drugs into a closed column of CSF, which instantaneously transmits pressure changes throughout the CSF column, such as those that occur with coughing or straining.
  1. Factors influencing block height
    1. Controllable factors
    2. Dose (volume × concentration)  
    3. Site of injection along neuraxi
    4. Baricity of local anesthetic solution
    5. Posture of patient
    6. Direction of bevel
    7. Factors not controllable
    8. Volume of cerebrospinal fluid  
    9. Density of cerebrospinal fluid
  2. Factors probably unrelated to the height of spinal anesthetic block
    1. Added vasoconstrictor
    2. Coughing, straining, or bearing down (labor)
    3. Barbotage
    4. Rate of injection (except hypobaric)
    5. Needle bevel (except Whitacre needle)
    6. Gender
    7. Weight
Intraoperatively, during high spinal anesthesia, patients occasionally complain excessively about dyspnea.


High Spinal = Block too high. The patient may complain of difficulty in breathing or of tingling in the arms or hands. Do not tilt the table "head up". 
  1. Signs / Symptoms.
    1. Nausea or vomiting. This may occur with high spinal blocks that may be associated with hypotension. Check the blood pressure and treat accordingly.
    2. Hypotension - Remember that nausea may be the first sign of hypotension. Repeated doses of vasopressors and large volumes of fluid may be necessary. 
    3. Bradycardia - give atropine. If this is not effective give ephedrine or adrenaline. 
    4. Increasing anxiety - reassure. 
    5. Numbness or weakness of the arms and hands, indicating that the block has reached the cervico-thoracic junction. 
    6. Difficulty breathing - as the intercostal nerves are blocked the patient may state that they can't take a deep breath. As the phrenic nerves (C3,4,5) which supply the diaphragm becomes blocked, the patient will initially be unable to talk louder than a whisper and will then stop breathing. 
    7. Loss of consciousness.
  2. Treatment of Total Spinal Block
    1. Although rare, total spinals can occur with frightening rapidity and result in the death of the patient if not quickly recognized and treated. 
    2. They are more likely to occur when a planned epidural injection is, inadvertently, given intrathecally. The warning signs that a total spinal block is developing are: hypotension and bradycardia. 
    3. Treat hypotension and bradycardia with intravenous fluids, atropine and vasopressors as described earlier. If treatment is not started quickly the combination of hypoxia, bradycardia and hypotension may result in a cardiac arrest.
  1. Post Operative
    1. Urinary retention --> Most common post operative complication.
    2. Backache
    3. Neurological complications:
    4. Post spinal headache
      1. It is low pressure headache due to seepage of CSF through dural puncture site
      2. Usually occipital in region, may present with neck pain & neck stiffness (May be frontal
      3. Present after 48 -72 hrs.
    5. Rx - Preventive
      1. Use of small gauge needles
      2. Use of pencil tip (dural separating) needles
      3. Adequate hydration
      4. Patient sits minimum in post. op. (i.e Lies supine for 24 hours)
      5. Avoidance of pillow for 24 hrs.
    6. Treatement
      1. Analgesia
      2. i / v or oral fluids
      3. abdominal binders
      4. injection of 25 - 50 ml of NS in epidural space
      5. Injection of 15 - 20 ml of autologous blood in epidural space --> Relieves headache in > 95% pat.
    7. Recent trends-
      Low molecular weight dextran has been used as a substitute for the EBP. Injecting 20 - 30 ml of dextran has been highly successful in treating the headaches.
      Gelatin powder (Gelfoam) and fibrin glue have both been used as epidural patches for postdural puncture headaches. They may be effective, but are significantly more difficult to administer than dextran
    8. Cauda equina syndrome
    9. Paraplegia (mostly because of epidural hematoma)
      Rx: Exploration & drainage of haematoma
    10. Paralysis of cranial N.
    11. 6th most commonly (1,9th, 10th are not involved)
    12. Anterior spinal A. Syndrome
    13. Meningitis

Epidural Anaesthesia

  1. The drug is injected outside the dura
  2. Most commonly used in post, op. analgesia through continuous epidural catheter
  3. Used for painless labour
  4. Usually epidural space is encountered at 4-5 cms.
  5. epidural space has negative pressure
  6. Drug used for epidural
    1. Lignocaine 1-2% 2-3 ml of drug is required to block 1 segment.
    2. Bupivacaine 0.25% - 0.5%
  7. Normally 15-20 ml of drug is required so there are ­chances of total spinal & LA toxicity (also epidural space has large no. of venous plexus of Batson)
  8. Needle used in Tuohy needle
  9. Methods
    1. loss of resistance technique
    2. Hanging drop technique - Gutierrzer’s sign - sudden sucking of drop in epidural space
  10. Duran’s sign --> Rapid injection of drug in extradural space causes ­in rate & depth of respiration
  11. West pal sign : Absence of knee jerk after epidural
  12. Advantage over spinal
    1. Less hypotension
    2. No post spinal headache
    3. Level of block can be changed
    4. Any duration of surgery can be performed
  13. Disadvantages:
    1. Patchy block very common
    2. Chances of unsuccessful block high
    3. Epidural haematoma can cause paraplegia
    4. High chances of total spinal
    5. Intravascular injection of drug is more common
    6. Technically difficult
    7. Expensive
    8. Effect takes place in 15-20 min

Combined spinal epidural

The combined spinal epidural has now become very routine, particularly.
  1. For longed surgeries like orthopedic surgeries, surgeries in which postoperative pain relief should be there.
  2. In this technique spinal needle is inserted through epidural needle and after giving hyperbaric solution the spinal needle is removed and epidural catheter is inserted.
  3. The advantage is that adequate effect is achieved through spinal (because patchy incomplete block is common if only epidural is given) and epidural catheter can be utilized for postoperative pain relief and secondly if surgery is prolonged it can be performed by giving top up doses through epidural catheter.

Caudal Block

  1. Drug injected (Lignocaine 2 mg/kg) in sacral hiatus
  2. Most commonly used in children
  3. Good for perineal surgeries
  4. (saddle in excellent for perineal surgeries)
  5. Average capacity of sacral canal in male - 34 ml; female -32 ml

Remifentanil is not given intrathecally in children for caudal anaesthesia Remifentanil is not given intrathecally in children for caudal anaesthesia (AIPG 11)

Saddle block

  1. IT is type of spinal block
  2. perineal area is blocked in this block
  3. less of haemodynamic alteration
  4. less amount of drug is required
  5. caesarean section cannot be done under this block.
  1. Opioids for Intrathecal
    1. 0.25 mg of morphine, Onset 20-30 min. Effect last for 4-6 hrs.
    2. 25 mg of fentanyl, Onset 5-10 min. Effect last for 1 hr.
  2. For epidural
    1. Morphine 4-6 mg (diluted in 10ml saline) Onset 30 min. last for 12 - 16 hrs.
    2. 100 mg of fentanyl (diluted in 10ml saline) Onset 10 min. last for 2-3 hrs.
  3. Level of block required for common surgeries
    1. LSCS - up to T6
    2. Prostate - up to T10
    3. Kidneys - up to T6
    4. Testicular surgeries - up to T10
    5. Perineal - Sacral plexus block is sufficient
    6. Hernia- up to T10
    7. Appendix- T8 - T10

Nerve blocks

  1. Upper extremity block
    1. Brachial plexus block
      1. Can be blocked by: Interscalene approach:
      2. Brachial plexus is blocked between anterior and middle scalene.
      3. Chances of sparing of ulnar nerve are high.
      4. Complications:
        1. Phrenic nerve block                        
        2. Neuritis
        3. Epidural & intrathecal injection               
        4. Intravascular injection
        5. Horner syndrome
    2. Supraclavicular Approach
      1. Most commonly used approach
      2. Blocked lateral to subclavian artery
      3. Complication:
        1. Pneumothorax (0.5-6%) 98% resolve by themselves                             
        2. Phrenic N. block (40-60%)
        3. Neural injury                                       
        4. Intravascular injection
        5. Horner syndrome due to block of cervical symp. Chain
          It consists of:
          • Ptosis
          • Miosis
          • Absence of papillary dilatation on shading the eye
          • Enophthalmos
          • Anhidrosis over the ipsilateral face & neck extending up to T3 spine
          • Absence of ciliospinal reflex (Dilatation of pupil when skin over neck is pinched)
    3. Axillary Approach
      1. Very commonly used block
      2. Adv.; No chances of pneumothorax & phrenic N. paralysis
      3. Disadv:. Musculocutaneous N. & intercostobrachial (T2) are spared; so difficult to use in arm surgery.
      4. Complications:
        1. Intravascular injection                       
          NOTE: Stellate ganglion block produces Horner’s
        2. Hematoma                                 
        3. Infection                   
        4. Neural injury                            
    4. Infraclavicular approach
      1. Chances of block failure is very high, Theoretically chances of pneumothorax can be avoided
      2. Each N. Can be separately blocked at elbow or wrist.
    5. Lower extremity blocks
      1. Not all popular because of spinal & epidural anaesthesia
      2. Psoas compartment block to block lumbar plexus
      3. 3 in 1 block (perivascular block) Drug is injected, in femoral canal while maintaining distal pressure will result in spread of drug resulting in lumbar plexus block.
        1. Femoral N. block
        2. Obturator N. block
        3. Sciatic N. block
        4. Ankle block (Deep peroneal, Superficial peritoneal & saphenous N. are blocked)
    6. Blocks of head & neck
      1. Trigeminal N. block
      2. Gasserian ganglion block for trigeminal neuralgia
      3. Cervical plexus block for carotid enterectomy
      4. Brachial plexus block:  
        1. Hoarseness(blockade of RLN)               
        2. Osteitis
        3. Mediastinitis(oesophageal puncture
      5. Phrenic N. block given at posterior border of SCM
      6. Stellate ganglion block:
  2. Stellate ganglion block:
    1. Indications-
      1. Pain syndrome             
        1. CPRS type 1 and 2                 
        2. Refractory angina                
        3. Phantom limb pain
      2. Vascular insufficiency
        1. Raynaud’s syndrome                      
        2. Scleroderma
        3. Frost bite                                           
        4. Obliterative vascular disease
    2. Anatomy of stellate ganglion:
      The stellate ganglion refers to the ganglion formed by the fusion of the inferior cervical and the 1st thoracic ganglion as they meet anterior to the vertebral body of C7. Clinical Signs of stellate ganglion block
      1. Eye; ptosis, narrowing of the palpebral fissure, miosis, enophthalmos, conjuctival injection(Guttmann sign) and lacrimation.
      2. Face and neck: anhidrosis, elevation local temperature and nasal stuffiness
      3. Arm: increased temperature and plethysmographic evidence of improved cutaneous blood flow.
    3. Complication- (Intravascular and subarchnoid injection can manifest as bradycardia)
      1. Hematoma
      2. Pneumothorax
      3. Epidural anesthesia
      4. Brachial plexus block
      5. Hoarseness (blockade of RLN)
      6. Osteitis
      7. Mediastinitis (oesophageal puncture
        Thus we can see bradycardia can be complication but not clinical sign of stellate ganglion block.
    4. Airway block
      1. Glossopharyngeal – base of anterior tonsillar pillar
      2. Superior laryngeal – below tip of greater cornu of hyoid bone
      3. Recurrent laryngeal – transtracheal (cricothyroid membrane)
    5. Block of abdomen & thorax
      • Intercostal N. block
      • Celiac plexus block (most common complication postural hypotension) (AIIMS May 09)
      • Lumbar sympathetic chain block for Burger disease
      • Paravertebral block The TPVS is a wedge-shaped space that lies on either side of the vertebral column. Its anatomic features are as follows:
  1. Boundaries of TPVS (Thoracic Para Vetebral Space):
    1. Anterior/lateral: Parietal pleura
    2. Posterior: Superior costo-transverse ligament
    3. Medial: Postero-lateral aspect of the vertebral body, intervertebral disc and the intervertebral foramen
  2. Communications:
    1. Intercostal space laterally
    2. Epidural space and subarachnoid space medially
    3. Paravertebral space on the other side via the prevertebral and epidural space.
  3. Contents: TPVS contains fatty tissue, within which lies the intercostal (spinal) nerve, the dorsal ramus, the intercostal vessels, the rami communicantes, and, anteriorly, the sympathetic chain. The spinal nerves in the TPVS are devoid of a fascial sheath, which makes them exceptionally susceptible to local anesthetic.
    1. Hypotension is uncommon, even after bilateral blocks.
    2. Dural puncture-related complications such as intrathecal injection, spinal anesthesia, and postural headache appear to be exclusive to the medial approach to the TPVS and are probably related to the closer proximity of the needle to the dural cuff and intervertebral foramen.
    3. Transient Horner’s syndrome, ipsilateral or bilateral, caused by spread of anesthetic to stellate ganglion, or preganglionic high thoracic fibres.
    4. Ipsilateral arm sensory changes (spread to T1 component of brachial plexus)
    5. Pulmonary hemorrhage (1 report with block following previous thoracic surgery
Intravenous Regional Anaesthesia (Bier’s block) (Ref. Paul’s aneasthesiology 5th ed. 199)
  1. IVRA, a simple method of providing anaesthesia of the distal arm or leg was first described by August Bier in 1808.
  2. Technique
    • After applying adequate functioning tourniquet, 30-40 cc 0.5% xylocaine or prilocaine is injected into the vein.
    • Deflation or leak can cause drug toxicity and death.
    • Bupivacaine is contraindicated for the use in Bier’s block as it is highly cardioitoxic.
    • Xylocaine with adrenaline is also contraindicated.
    • Injection of the drug should be as distal as possible.
    • Tourniquet can be released after ½ hr
    • Contraindications : Sickle cell disease, scleroderma and raynauds phenomenon.
  3. Adv:.
    1. Easy procedure
    2. Rapid onset
    3. Good muscle relaxation
  4. Complications
    1. Tourniquet discomfort
    2. Difficulty in providing blood less field
    3. Accidental deflation or leak can cause drug toxicity & death
    4. Compartment syndrome

Coeliac Plexus Block

  1. Indications
    For relief of pain from non-pelvic intra-abdominal organs.
    1. Acute pain - may be performed during surgery for postoperative pain relief.
    2. Chronic pain - useful for any condition that causes chronic severe upper abdominal visceral pain - e.g. chronic pancreatitis (local anaesthetic blocks only).
    3. Cancer pain - useful for upper abdominal organ cancer pain, and is frequently used for carcinoma of the pancreas - initial diagnostic local anaesthetic block, followed by neurolytic block.
  2. Contraindications
    1. Bleeding and infection risks.
    2. Where the source of the pain is no longer being transmitted through the autonomic nerves.
    3. It is dangerous to perform the block in the presence of a large aortic aneurysm.
  3. Anatomy
    1. The coeliac plexus is also known as the solar plexus. It is the main junction for autonomic nerves supplying the upper abdominal organs (liver, gall bladder, spleen, stomach, pancreas, kidneys, small bowel, and 2/3 of the large bowel).
    2. The celiac plexus proper consists of the celiac ganglia with a network of interconnecting fibers.
    3. The ganglia lie on each side of L1 (aorta lying posteriorly, pancreas anteriorly and inferior vena cava laterally).
  4. Sympathetic supply:
    1. Greater splanchnic nerve (T5/6 to T9/10)
    2. Lesser splanchnic nerve (T10/11)
    3. Least splanchnic nerve (T11/12)
      The upper abdominal organs receive their parasympathetic supply from the left and right vagal trunks, which pass through the coeliac plexus but do not connect there.
  5. ​​​Technique
    1. The block is performed using X-ray screening, intravenous sedation, local anaesthetic infiltration of the superficial layers, with the patient in the prone position. 
    2. Intravenous fluids are required pre-block to reduce the risk of hypotension after the procedure. It normally takes two needle insertions, one on each side to block both of the coeliac ganglia, but on some occasions good spread to both sides is achieved just using one needle. 
    3. The needle entry point is just below the tip of the 12th rib, and using X-ray screening in two planes, the needle is advanced until it hits the side of the L1 vertebra.
      The needle is withdrawn slightly and then redirected forwards until it is in the area of the coeliac plexus, avoiding the aorta and inferior vena cava. Radio-opaque dye is injected to confirm the correct placement of the needle, and then the appropriate mixture is injected:
      1. For non-malignant pain: 10 ml 0.5% Chirocaine on each side
      2. For malignant pain: 5 ml 6% aqueous phenol + 5 ml 0.5% Chirocaine on each side
        As the block causes dilatation of the upper abdominal vessels, venous pooling can occur, leading to hypotension. This can be exacerbated by pre-existing dehydration, hence the need for IV hydration before performing the block.
  6. Complications
    1. Severe hypotension may result, even after unilateral block. 
    2. Bleeding due to aorta or inferior vena cava injury by the needle. 
    3. Intravascular injection (should be prevented by checking the needle position with radio-opaque dye). 
    4. Upper abdominal organ puncture with abscess/cyst formation. 
    5. Paraplegia from injecting phenol into the arteries that supply the spinal cord (prevented by checking the needle position with radio-opaque dye). 
    6. Sexual dysfunction (injected solution spreads to the sympathetic chain bilaterally).
      Intramuscular injection into the psoas muscle. 
    7. Lumbar nerve root irritation (injected solution tracks backwards towards the lumbar plexus). 
    8. Reference; miller anaesthesia, 5th ed

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