1. Brachial Plexus Block (for upper limb anesthesia)

• Injection site:

  • Interscalene block: At the level of C6, between the anterior and middle scalene muscles.
  • Supraclavicular block: Above the clavicle, near the brachial plexus trunks.
  • Infraclavicular block: Below the clavicle near the cords of the brachial plexus.
  • Axillary block: Near the axillary artery, at the level of the axilla.

• Clinical relevance: Used for surgeries of the shoulder, arm, forearm, and hand.

• Key point: Interscalene block can cause phrenic nerve paralysis (C3-C5), leading to diaphragmatic hemiparalysis.

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2. Epidural Anesthesia

• Injection site:
  • Into the epidural space, typically at lumbar levels (L3-L4, L4-L5), via the ligamentum flavum.
• Clinical relevance: Used for labor analgesia, lower limb and abdominal surgeries.
• Key point: Avoid dural puncture to prevent post-dural puncture headache.

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3. Spinal Anesthesia

• Injection site:
  • Into the subarachnoid space, usually at L3-L4 or L4-L5 interspace.
• Clinical relevance: Used for lower limb, pelvic, and lower abdomen surgeries.
• Key point: Fast onset and denser block; risk of hypotension due to sympathetic blockade.

Feature	Epidural Anesthesia	Subarachnoid (Spinal) Anesthesia
Injection site	Epidural space	Subarachnoid space (CSF)
Onset	10-20 min	2-5 min
Duration	Variable, hours to days (infusion possible)	Limited to single shot duration (1.5-4 h)
Block density	Segmental; can be titrated	Dense and profound motor and sensory block
Sympathetic blockade	Variable, less profound	Usually marked hypotension
Use	Labor analgesia, postoperative pain control, major thoracoabdominal surgery	Lower limb, pelvic, lower abdominal surgery with rapid onset
Main complications	Epidural hematoma/abscess, accidental dural puncture, patchy block	Post-dural puncture headache, hypotension, total spinal

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4. Sciatic Nerve Block

• Injection site:
  • Posteriorly in the gluteal region or mid-thigh.
• Clinical relevance: Used for anesthesia of the lower limb below the knee.
• Key point: Useful in foot and ankle surgeries.

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5. Femoral Nerve Block

• Injection site:

  • Just distal to the inguinal ligament, lateral to the femoral artery and vein. The nerve lies lateral to the femoral artery in the femoral triangle.

• Clinical relevance:

  • Provides anesthesia to the anterior thigh, knee, and medial leg (via saphenous nerve branch).
  • Frequently used in surgeries involving the anterior thigh, knee arthroscopy, or for pain control after femur fractures.

• Anatomical landmarks:

  • Needle insertion usually at the level of the femoral triangle, found using the inguinal ligament superiorly, sartorius muscle laterally, and adductor longus muscle medially.
  • Palpate femoral artery, insert needle just lateral to artery.

6. Digital Nerve Block

• Injection site:
  • At the base of the fingers, near the digital nerves.
• Clinical relevance: For finger surgeries.
• Key point: Avoid intravascular injection to prevent systemic toxicity.