Anatomy of nerve blocks
Topical local nerve blocks
1) Auriculopalpebral block
To desentitise the auriculopalpebral nerve that supplies motor fibres to the orbicularis oculi
muscle. The nerve runs from the base of the ear along the facial crest , past and ventral of
the eye , giving off branches on the way.
-indication- for examination of the eyeball(prevents eyelid closure during
examination/surgery of eyes)
-site- rostral to the base of the ear at the end of the zygomatic arch(at the caudo-dorsal
border of the zygomatic arch)
2) Cornual nerve block
-caudal to orbit, along the temporal line.
- For desentitisation of the horn during dehorning .
-opthalmic division of the fifth cranial nerve(trigeminal nerve)
- injected on the upper third of the temporal ridge
3) Paravertebral block
-abdominal wall: the distribution of lumbar spinal nerves
--important nerves to the abdominal wall to desensitize T13,L1,L2- to desensitize for
rumenectomy and c-section.
general distribution of the spinal nerve
-the spinal nerve-emerges from the vertebral canal-
Branches are: a) dorsal branch- supplies the epaxial muscle and
skin the dorsal part of the abdomen(between the midline (vertebra) to the level of the
b) ventral branch- supplies the flank(internal abdominal oblique,transverse abdominal muscle,
hypaxial, parietal peritoneum) .
c) skin-the lower flank and skin of abdominal floor. abdominal wall: caudoventral flow of sensory innervation
- skin area may be a dermatome- a dermatome is an area only supplied by one spinal nerve.
- Though there are areas of dermatome there is also an overlap of sites due to the pathway of
- As the spinal nerve leaves the intervertebral foramina- the dorsal and ventral branches pass
obliquely and ventrally.
2 techniques can be used for paravertebral nerve block
a) Proximal paravertebral nerve block
Needle is inserted close to the emergence of the nerve from the spinal cord
Both dorsal and ventral nerves will be desensitized.
Left side –it is closer to the aorta and on the right side it is closer to the vena cava.
Block at the emergence of the ner