The document explains dermatomes and myotomes, detailing their definitions and clinical significance. Dermatomes refer to the sensory distribution of nerve roots across the skin, while myotomes pertain to muscle groups supplied by these nerve roots, with patterns varying across different segments of the spinal cord. Understanding these concepts is important for localizing neurological conditions and assessing muscle weakness in relation to spinal injuries.

1. DERMATOMES AND
MYOTOMES
-Dr. Monica Dhanani

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

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

9. Myotomes:- are defined as groups of
muscles supplied by a single nerve root.

10. Clinical Significance
 Info. about the level in the spine where a lesion may be
present.
 Muscle weakness
 IV disc herniation

11.  C1-C2 : Cervical flexion
 C3: Cerviacl lateral flexion
 C4: shoulder elevation
 C5: shoulder abduction
 C6: elbow flexion
 C7: elbow extension
 C8: thumb extension
 T1: finger abd/add

12.  L2: hip flexion
 L3: knee extension
 L4: ankle DF
 L5: great toe extension
 S1: ankle Evn/hip extension/ankle PF/knee flexion
 S2: knee flexion

13. THANK YOU