2. Dermatomes:- the sensory distribution of each nerve
root is called the dermatomes.
The area of the skin supplied by a single nerve root
3. There are 31 segments of spinal cord each with a pair of
ventral and dorsal that innervate motor and sensory
function resp.
The anterior and posterior nerve roots combine on each
side to form the spinal nerve as they exit the vertebral canal
through IV foramina
The 31 spines segment on each side give rise to 31 spinal
nerves which are composed of 8C, 12T, 5L ,5S and 1C spinal
nerve
Dermatomes exist for each of the spinal nerve except C1
Sensory information form a specific dermatomes is
transmitted by the sensory nerve fibers to the spinal nerve
of a specific segment of spinal cord
Dermatomes along the arms and legs differs from the
pattern of the trunk dermatomes because they run
longitudinally along the limbs
4. Clinical Significance
dermatomes are useful to help localize neurological
levels particularly in radiculopathy.
Effacement or encroachment of a spinal nerve may or
may not exhibited symptoms in dermatomic area
covered by the compressed nerve root in addition to
weakness or dtr loss
Viruses that infect spinal nerves such as herpes zoster
reveal their origin by showing up as a pain full
dermatomic area
5. C1- vertex of skull
C2-forehead occiput
C3-neck,temporal area
C4-shoulder area,clavicles,upper scap
C5-deltoid, ant arm till base of thumb
C6-ant arm,rad side of hand to thumb n index finger
C7-Lat arm n forearm to index,long and ring fingers
C8-medial arm and forearm to long,ring and little fingers
T1-medial side of forearm to base of little finger
T2-medial side of upp arm to med elbow,pectoral and
midscapular area
T3 to T12- T3 to T6 upper thorax
T5-T7 coastal margin
T8-T12 abdomen and lumbar region
6.
7. L1-back,over trochanter and groin
L2-back,front of thigh and knee
L3-back,upper buttock,ant. thigh and knee,medial lower
leg
L4-medial buttock,lateral thigh,med.leg,dorsum of
foot,big toe
L5-buttock,post.and lat.thigh,lat.aspect of leg,dorsum of
foot,med.half of sole,first second and third toes
8. S1-buttock,thigh,and leg post.
S2-same as s1
S3-groin,med.thigh to knee
S4-perineum,genitals,lower sacrum