Spinal
nerve
How many Spinal
nerves present in our body? Number: 31 pairs. 8 cervical spinal nerve, 12
thoracic spinal nerve, 5 lumbar spinal nerve, 5 sacral spinal nerve and 1
coccygeal spinal nerve
How a spinal nerve
is formed? : Spinal nerve form by union
of ventral and dorsal nerve roots
Location of spinal
nerve: within the intervertebral foramen
Exit : C1-C7 spinal nerves exit ABOVE C1-C7 vertebrae
C8 spinal nerve projects below C7 vertebra
T1-S5 spinal nerves project BELOW T1-S5
vertebrae
Branches
of a Spinal Nerve:
1. dorsal ramus – supply deep muscles and skin of back
2.
ventral ramus – supply upper and lower extremities, ventrolateral trunk
3. meningeal branch
- back into the spinal column
4. rami communicantes
- for autonomic nerve fibers
Type of
spinal nerves: they are mixed nerve (both sensory and motor ).
Component: GSA (general somatic afferent –carry impulse from
periphery to CNS) and GSE( general somatic efferent- impulse goes from CNS to
skeletal muscle)
Plexus of spinal nerve: plexus of spinal nerve is formed
by ventral rami of different spinal nerves. There are four spinal nerve plexus present within the body.
|
Name of plexus
|
Formation
|
Supplied area
|
Important nerve of the plexus
|
|
1. cervical plexus
|
ventral rami of C1-C4 with some C5
|
a. muscles/skin of head, neck, some shoulder
b. phrenic nerve - diaphragm muscle (breathing)
|
phrenic nerve -
|
|
2. brachial plexus
|
ventral rami of C5-C8 and T1
|
Upper limb and
shoulder
|
Axillary N, musculocutanous
N,
Radial N, median N, Ulnar N
|
|
3. lumbar plexus
|
- ventral rami of L1-L4
|
a. abdominal wall, genitals, part of lower limb
|
Femoral N, Obturator N
|
|
4. sacral plexus
|
ventral rami of L4-L5 and S1-S4
|
a. buttocks, perineum, part of lower limb
b. sciatic nerve
|
Sacral n- largest nerve of body,
pudendal n, Sup
and inf
Gluteal n
|
Dermatomes: area of skin is supplied by single
spinal nerve
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