Myotomes & Dermatomes : Myotomes & Dermatomes DR . Mina Nasser Wagih
Under gradated 3 rd .year
Faculty of physical therapy
Cairo uni. The definition of each term : 2 The definition of each term Myotomes : Relationship between the spinal nerve & muscleDermatomes : Relationship between the spinal nerve & skin Myotomes : 3 Myotomes Each muscle in the body is supplied by a particular level or segment of the spinal cord and by its corresponding spinal nerve. The muscle, and its nerve make up a myotome. This is approximately the same for every person and are as follows:
C3,4 and 5 supply the diaphragm (the large muscle between the chest and the belly that we use to breath).
C5 also supplies the shoulder muscles and the muscle that we use to bend our elbow .
C6 is for bending the wrist back.
C7 is for straightening the elbow.
C8 bends the fingers.
T1 spreads the fingers.
T1 –T12 supplies the chest wall & abdominal muscles.
L2 bends the hip.
L3 straightens the knee.
L4 pulls the foot up.
L5 wiggles the toes.
S1 pulls the foot down.
S3,4 and 5 supply the bladder. bowel and sex organs and the anal and other pelvic muscles Dermatomes : 4 Dermatomes Dermatome is a Greek word which literally means "skin cutting". A dermatome is an area of the skin supplied by nerve fibers originating from a single dorsal nerve root. The dermatomes are named according to the spinal nerve which supplies them. The dermatomes form into bands around the trunk but in the limbs their organisation is more complex as a result of the dermatomes being "pulled out" as the limb buds form and develop into the limbs during embryological development.
In diagrams or maps, the boundaries of dermatomes are usually sharply defined. However, in life there is considerable overlap of innervation between adjacent dermatomes. Thus, if there is a loss of afferent nerve function by one spinal nerve sensation from the region of skin which it supplies is not usually completely lost as overlap from adjacent spinal nerves occurs: however, there will be a reduction in sensitivity. Levels of principal dermatomes : 5 Levels of principal dermatomes C5 Clavicles
C5, 6, 7 Lateral parts of upper limbs
C8, T1 Medial sides of upper limbs
C6, 7, 8 Hand
C8 Ring and little fingers
T4 Level of nipples
T10 Level of umbilicus
T12 Inguinal or groin regions
L1, 2, 3, 4 Anterior and inner surfaces of lower limbs
L4, 5, S1 Foot
L4 Medial side of great toe
S1, 2, L5 Posterior and outer surfaces of lower limbs
S1 Lateral margin of foot and little toe
S2, 3, 4 Perineum The Spinal cord : 6 The Spinal cord Dermatome map : 7 Dermatome map Dermatome map : 8 Dermatome map Spinal cord injury : 9 Spinal cord injury Key muscle : 10 Key muscle THANK YOU : 11 THANK YOU with my best wishes,,
Dr . Mina nasser