Important dermatomes and anatomical landmarks
| A | C5 | |
| B |
C6 |
|
| C |
C7 |
|
| D |
T1 |
The cutaneous innervation over the medial aspect of the elbow is represented by which dermatome?
| A |
C5 |
|
| B |
C6 |
|
| C |
C7 |
|
| D |
T1 |
The area of skin supplied by a single spinal (segmental) nerve is known as a dermatome.
The medial surface of the upper arm is supplied by the T2 dermatome, and the medial aspect of the lower arm, elbow, and proximal forearm by the T1 dermatome.
The T1 and T2 dermatomes frequently receive referred pain from the heart.
Little finger of the hand corresponds to which dermatome?
| A | C6 dermatome | |
| B | C7 dermatome | |
| C |
C8 dermatome |
|
| D |
T1 dermatome |
C i.e. C8 dermatome
Dorsal surface of proximal phalanx of thumb corresponds to C6, middle finger to C7 and little finger to C8.
A 45 year old male has multiple grouped vesicular lesions present on the T10 segment dermatome associated with pain. The most likely diagnosis is
| A |
Herpes zoster |
|
| B |
Dermatitis herpetiformis |
|
| C |
Herpes simplex |
|
| D |
Scabies |
A i.e. Herpes zoster
Herpes zoster, also known as shingles, is caused by reactivation of endogenous latent varicella-zoster virus (VZV) that resides in a sensory dorsal root ganglion . Herpes zoster can develop any time after a primary infection with VZV (i.e., varicella or chickenpox) or varicella vaccination. The activated virus travels back down the corresponding cutaneous nerve to the adjacent skin, causing typically a painful, unilateral vesicular eruption in a restricted dermatomal distribution.
Nerve root for dermatome supplying thumb and index finger:
| A |
C6 C8 |
|
| B |
C6 C7 |
|
| C |
C7 C8 |
|
| D |
C5 C6 |
Ans. b. C6 C7
| Nerve root | Dermatome |
| C5 | Deltoid patch |
| C6 | Lateral forearm |
| Radial side of hand | |
| Thumb and index finger | |
| C7 | Posterior lateral arm and forearm |
| Middle finger, Index finger | |
| C8 | Medial forearm |
| Ulnar border of hand | |
| Ring and little finger | |
| T1 | Medial elbow and arm |
A 60-year old male presents with painful, 141 oupet. vesicles over erythematous plaques in T3 dermatome region of trunk. Which of the following would be the most likely causative organism?
| A | Varicella zoster | |
| B |
Herpes simplex |
|
| C |
Pox virus |
|
| D |
Papilloma virus |
Ans. a. Varicella zoster
A 60-year-old male presents with painful, grouped vesicles over erythematous plaques in T dermatome region of trunk. Varicella zoster is the most likely causative organism.
| A |
Varicella zoster |
|
| B |
Herpes simplex |
|
| C |
Human papilloma virus |
|
| D |
Pox virus |
Ans. a. Varicella zoster
Herpes Zoster
- Caused by Varicella Zoster (chicken pox) virusQ one attack gives life long immunity
- Thoracic nerves (intercoastal nerves)Q, ophthalmic division of trigeminal nerve and other spinal nerves are most commonly affectedQ
Pathology:
- Ballooning is characteristicQ
Clinical Features:
- Prodrome of segmental pain begins 1-4 days before the eruptionQ, erythema and edema is rapidly followed by appearance of grouped vesicles unilateral and in a segmental distribution (MC thoracic dermatome)Q, mucous membrane within the affected dermatome may be involved
- Unilateral vesicular eruption within a dermatome associated with severe pain
- The dermatome from T3 to L3 are most frequently involve
Complications:
- Post-herpetic neuralgia° (persistent neuralgic pain)
- Corneal ulcer and scarring (zoster of ophthalmic division of trigeminal nerve), eye involvement is indicated when vesicles are present on the side of nose- Hutchinson’s signQ
Herpes Zoster
Variants:
- Ramsay Hunt Syndrome: H. zoster involving sensory branch of facial nerveQ
- Zoster opthalmicus: H. zoster involving ophthalmic division of trigeminal nerve .Q
Herpes simplex:
- Painful, cluster of vesicles on face
- Recurrent
- Two types:
- Type I: Oral lesions seen in childhood
- Type II: Genital lesions (is STD and carcinogenic) in young adults usually after sexual contact.