In spinal anaesthesia the drug is deposited between

Ans. is 'b' i.e., Pia and arachnoid matter Spinal anaesthesia In spinal anaesthesia LA is injected into subarachnoid space (space between pia matter and arachnoid matter). Structure pierced during SA (from outside in) - Skin - Subcutaneous tissue --> Supraspinous & intraspinous ligament --> Ligamentum falvum --> Duramater -->Arachnoidmater. Site of spinal anaesthesia L2_3 or L3_4 interveebral space in adult (In adult spinal cord ends at lower border of Ll veebrae). L4_5 interveebral space in children (spinal cord ends at lower border of L3 veebrae in children). Spinal anaesthesia leads to creation of a zone of differential blockade, ie motor fibres are blocked two levels lower and autonomic fibres are blocked two levels higher than the sensory blockade due to different sensitivity of different fibres.