myotome and dermatome

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 Thumb 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 minanasser27@yahoo.com