Dermatomes & Myotomes By Firdous Hussain

Significance of Dermatomes & Myotomes a Physiotherapy perspective

1. DERMATOMES AND M Y O T OMES Firdous Hussain. F Final Yr BPT

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. Full Dermatome Map

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. 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

7. S1-buttock,thigh,and leg post. S2-same as S 1 S3-groin,med.thigh to knee S4-perineum,genitals,lower sacrum

8. 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

9. Clinical Significance

10. Clinical Significance Clinical Significance

11. Myotomes :- Myotomes correspond to muscles that are controlled by specific nerve roots from the spinal cord Muscles (movement) are innervated by single nerve roots called myotome s

12. Myotomes and Differentiating Nerve Lesions C1 Myotome Upper cervical flexion C2 Myotome Upper cervical extension/ Neck Rotation C3 Myotome Cervical lateral flexion C4 Myotome Shoulder shrugs (upper trapezious ) C5 Myotome Shoulder abduction and external rotation( infraspinatus ) C6 Myotome Elbow flexion and wrist extension C7 Myotome Elbow extension and wrist flexion C8 Myotome Thumb extension and ulnar deviation T1 Myotome Finger adduction and abduction

13. L1 Myotome Hip flexion L2 Myotome Hip flexion (also adduction and medial rotation) L3 Myotome Leg/knee extension L4 Myotome Dorsiflexion L5 Myotome Great/Big toe extension S1 Myotome Ankle plantar flexion and eversion/knee flexion S2 Myotome Ankle plantar flexion and knee flexion S3 Myotome None S4 Myotome Bladdar and rectum

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

15. DERMATOMES AND MYOTOMES AND ITS CLINICAL ‘’SPECIAL TEST’’ IN UPPER LIMB AND LOWER LIMB

16. Nerves and nerve roots are typically injured by compression or stretching forces When a nerve root is damaged a deficit may occur in the corresponding Limb The evaluation of nerve root damage can be done by testing dermatomes and myotomes

17. Dermatome (sensory) test: Pain sensation (pin prick) and light touch sensation (cotton wool) 1. PINPRICK TEST Gently touches the skin with the pin or back end and asks the patient whether it feels sharp or blunt 2. LIGHT TOUCH TEST Dabbing a piece of cotton wool on an area of skin

18. Upper Body Test Points C2 - Occipital Protuberance C3 - Supraclavicular Fossa C4 - Acromioclavicular Joint C5 - Lateral Antecubital Fossa C6 - Thumb C7 - Middle Finger C8 - Little Finger T1 - Medial Antecubital Fossa T2 - Apex of Axilla Lower Body Test Points L1 - Upper Anterior Thigh L2 - Mid Anterior Thigh L3 - Medial Femoral Condyle L4 - Medial Malleolus L5 - Dorsum 3rd MTP Joint S1 - Lateral Heel S2 - Popliteal Fossa S3 - Ischial Tuberosity S5 - Perianal Area F R O NT Test Dermatomes at dots 1. PINPRICK TEST

19. Upper Body Test Ponits C2 - Occipital Protuberance C3 - Supraclavicular Fossa C4 - Acromioclavicular Joint C5 - Lateral Antecubital Fossa C6 - Thumb C7 - Middle Finger C8 - Little Finger T1 - Medial Antecubital Fossa T2 - Apex of Axilla Lower Body Test Points L1 - Upper Anterior Thigh L2 - Mid Anterior Thigh L3 - Medial Femoral Condyle L4 - Medial Malleolus L5 - Dorsum 3rd MTP Joint S1 - Lateral Heel S2 - Popliteal Fossa S3 - Ischial Tuberosity S5 - Perianal Area BACK 1. PINPRICK TEST

20. Upper Body Test Po ints C2 - Occipital Protuberance C3 - Supraclavicular Fossa C4 - Acromioclavicular Joint C5 - Lateral Antecubital Fossa C6 - Thumb C7 - Middle Finger C8 - Little Finger T1 - Medial Antecubital Fossa T2 - Apex of Axilla 1. PINPRICK TEST

21. 2. LIGHT TOUCH TEST

22. 2. LIGHT TOUCH TEST

23. 2. LIGHT TOUCH TEST

24. 2. LIGHT TOUCH TEST

25. 2. LIGHT TOUCH TEST

26. 2. LIGHT TOUCH TEST

27. 2. LIGHT TOUCH TEST

28. 2. LIGHT TOUCH TEST – LOWER LIMB

29. 2. LIGHT TOUCH TEST - LOWER LIMB

30. 2. LIGHT TOUCH TEST - LOWER LIMB

31. 2. LIGHT TOUCH TEST - LOWER LIMB

32. 2. LIGHT TOUCH TEST - LOWER LIMB

33. 2. LIGHT TOUCH TEST - LOWER LIMB

34. 2. LIGHT TOUCH TEST - LOWER LIMB

35. Myotome (motor) test: Myotomes correspond to muscles that are controlled by specific nerve roots from the spinal cord Muscles (movement) are innervated by singe nerve roots called myotome s

36. Cervical Plexus : C1-C4 nerve roots innervate the diaphragm, shoulder and neck. Brachial Plexus : C5-T1 nerve roots innervate the upper limbs Lumbosacral Plexus : L1- L5, S2 nerve roots innervate the lower extremity

37. Upper Extremity Nerve Routes C4 C5 C6 C7 C8 T1 tested with resisted shoulder shrugs/elevation tested with resisted shoulder abduction tested with resisted elbow flexion/ wrist extension tested with resisted wrist flexion tested with resisted thumb extension fingers abduction & adduction Lower Extremity Nerve Routes The quick test for the lower extremity, to rule out a nerve root injury is to have the athlete do a squat. L1-L2 tested with resisted hip flexion L3 tested with resisted knee extension L4 tested with resisted foot dorsi flexion L5 tested with resisted great toe extension S1/S2 tested with plantar flexion

38. Starting with the deltoids, ask the patient to raise both their arms in front of them simultaneously as strongly as then can while the examiner provides resistance to this movement. Compare the strength of each arm. The deltoid muscle is innervated by the C5 nerve root via the axillary nerve. C5- Shoulder

39. Next, ask the patient to extend and raise both arms in front of them. Ask the patient to keep their arms in place while they close their eyes and count to 10. Normally their arms will remain in place. If there is upper extremity weakness there will be a positive pronator drift, in which the affected arm will pronate and fall. This is one of the most sensitive tests for upper extremity weakness. Pronator drift is an indicator of upper motor neuron weakness. In upper motor neuron weakness, supination is weaker than pronation in the upper extremity, leading to a pronation of the affected arm. The patient to the left does not have a pronator drift. C5- Shoulder

40. C6- Elbow flexion Test the strength of lower arm flexion by holding the patient's wrist from above and instructing them to "flex their hand up to their shoulder". Provide resistance at the wrist. Repeat and compare to the opposite arm. This tests the biceps muscle. The biceps muscle is innervated by the C5 and C6 nerve roots via the musculocutaneous nerve.

41. Test the strength of wrist extension by asking the patient to extend their wrist while the examiner resists the movement. This tests the forearm extensors. Repeat with the other arm. The wrist extensors are innervated by C6 and C7 nerve roots via the radial nerve. The radial nerve is the "great extensor" of the arm: it innervates all the extensor muscles in the upper and lower arm. C6- Wrist Extension

42. C7- Elbow extension Now have the patient extend their forearm against the examiner's resistance. Make certain that the patient begins their extension from a fully flexed position because this part of the movement is most sensitive to a loss in strength. This tests the triceps. Note any asymmetry in the other arm. The triceps muscle is innervated by the C6 and C7 nerve roots via the radial nerve.

43. C8- Finger Flexion Examine the patient's hands. Look for intrinsic hand, thenar and hypothenar muscle wasting. Test the patient's grip by having the patient hold the examiner's fingers in their fist tightly and instructing them not to let go while the examiner attempts to remove them. Normally the examiner cannot remove their fingers. This tests the forearm flexors and the intrinsic hand muscles. Compare the hands for strength asymmetry. Finger flexion is innervated by the C8 nerve root via the median nerve.

44. C8- Finger abduction & adduction Test the intrinsic hand muscles once again by having the patient abduct or "fan out" all of their fingers. Instruct the patient to not allow the examiner to compress them back in. Normally, one can resist the examiner from replacing the fingers. Finger abduction or "fanning" is innervated by the T1 nerve root via the ulnar nerve.

45. C8 & T1- Thumb Opposition To complete the motor examination of the upper extremities, test the strength of the thumb opposition by telling the patient to touch the tip of their thumb to the tip of their pinky finger. Apply resistance to the thumb with your index finger. Repeat with the other thumb and compare. Thumb opposition is innervated by the C8 and T1 nerve roots via the median nerve.

46. L1 & L2 : Hip Flexion Proceeding to the lower extremities, first test the flexion of the hip by asking the patient to lie down and raise each leg separately while the examiner resists. Repeat and compare with the other leg. This tests the iliopsoas muscles. Hip flexion is innervated by the L2 and L3 nerve roots via the femoral nerve.

47. Test extension at the knee by placing one hand under the knee and the other on top of the lower leg to provide resistance. Ask the patient to "kick out" or extend the lower leg at the knee. Repeat and compare to the other leg. This tests the quadriceps muscle. Knee extension by the quadriceps muscle is innervated by the L3 and L4 nerve roots via the femoral nerve. L3: Knee Extension

48. L4: Ankle Dorsiflexion Test dorsiflexion of the ankle by holding the top of the ankle and have the patient pull their foot up towards their face as hard as possible. Repeat with the other foot. This tests the muscles in the anterior compartment of the lower leg. Ankle dorsiflexion is innervated by the L4 and L5 nerve roots via the peroneal nerve.

49. L5: Great toe extension Ask the patient to move the large toe against the examiner's resistance "up towards the patient's face". This tests the extensor halucis longus muscle. The extensor halucis longus muscle is almost completely innervated by the L5 nerve root

50. S1&S2: Ankle plantar flexion and eversion/knee flexion Holding the bottom of the foot, ask the patient to "press down on the gas pedal" as hard as possible. Repeat with the other foot and compare. This tests the gastrocnemius and soleus muscles in the posterior compartment of the lower leg. Ankle plantar flexion is innervated by the S1 and S2 nerve roots via the tibial nerve Ankle Plantar Flexion

51. Knee Flexion Test flexion at the knee by holding the knee from the side and applying resistance under the ankle and instructing the patient to pull the lower leg towards their buttock as hard as possible. Repeat with the other leg. This tests the hamstrings. The hamstrings are innervated by the L5 and S1 nerve roots via the sciatic nerve. S1&S2: Ankle plantar flexion and eversion/knee flexion

52. Tenderness :- Tenderness is a pain or discomfort when an affected area is touched or palpated How Hard Should Tender Point Be Palpated? Palpate such that minimum pressure is used to elicit jump / jerk sign. Characterized by responses, such as a sudden jerking motion, grabbing of the therapist’s hand, a facial grimace. Depth of tissue being palpated Firm, but tissue must be entered gently, and only necessary pressure must be used to palpate through layers of tissue

53. How is the severity of tenderness graded? Grade 1: Patient complains of pain Grade 2: Patient complains of pain and winces Grade 3: Patient winces and withdraws (Jump Sign) the joint Grade 4: patient will not allow palpation ( (Jump Sign With Non Noxious Stimulus) Another method of grading is: Extremely sensitive; visual jump sign is present and the patient expresses extreme sensitivity to touch Very sensitive; very tender but no jump sign Moderately sensitive; patient states that the point is tender to touch but does not flinch or jump away. No tenderness

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