Nerve Root Dermatomes, Myotomes, Reflexes Flashcards
C1 Dermatome
Vertex of skull
C2 dermatome
Temple, forehead, occiput
C2 myotome (muscle weakness)
- Longus colli
- SCM
- Rectus capitis
C3 dermatome
Entire neck, posterior cheek, temporal area, prolongation forward under mandible
C3 Myotome (muscle weakness)
Trapezius, selenium capitis
C3 Paresthesias
Cheek and side of neck
C4 dermatome
Shoulder area, clavicular area, upper scapular area
C4 myotome (muscle weakness)
Trapezius, levator scapulae
C4 paresthesia
Horizontal band along clavicle and upper scapula
C5 dermatome
Deltoid area, Anterior aspect of entire arm to base of thumb
C5 myotome (muscle weakness)
Supraspinatus, infraspinatus, deltoid, biceps
C5 Reflexes affected
Biceps, brachioradialis
C6 dermatome
Anterior arm, radial side of hand to thumb and index finger
C6 myotome (muscle weakness)
Biceps, Supinator, wrist extensors
C6 reflex affected
Biceps, brachioradialis
C6 parasthesias
Thumb and index finger
C7 dermatome
Lateral arm and forearm to index, long, and ring fingers
C7 myotome (muscle weakness)
Triceps, wrist flexors (rarely wrist extensors)
C7 reflexes affected
Triceps
C7 paresthesias
Index, long and ring fingers
C8 dermatome
Medial arm and forearm to long, ring, and little fingers
C8 myotome (muscle weakness)
Ulnar debaters, thumb extensors, thumb adductors (rarely triceps)
C8 Parasthesias
Little finger alone or with tow adjacent fingers; not ring or long fingers, alone or together (C7)
T1 dermatome
Medial side of forearm to base of little finger
T1 myotome, reflex affected, and paresthesias
Disk lesions at upper 2 thoracic Levels do not appear to give rise to root weakness. Weakness of intrinsic muscles of the hand is due to other pathology (e.g. thoracic outlet pressure, neoplasm of lung, ulnar nerve lesion)
T2 dermatome
Medial Side of upper arm to medial elbow, pectoral and midscapular areas
T3-T12 dermatomes
T3-T6: upper thorax
T5-T7: costal margin
T8-T12: abdomen and lumbar region
T3-T12 myotomes, affected reflexes, parasthesias
Articular and dural signs and root pain are common. Root signs (cutaneous analgesia) are rare and have such indefinite area that hey have little localizing value. Weakness is not detectable
L1 dermatome
Back, over trochanter and growing
L1 parasthesia
Groin; after holding posture which causes pain
L2 dermatome
Back, front of thigh to knee
L2 myotome (muscle weakness)
Psoas, hip adductors
L2 parasthesias
Occasionally anterior thigh
L3 dermatome
Back, upper buttock, anterior thigh and knee, medial lower leg
L3 myotome (muscle weakness)
Psoas, quadriceps, thigh atrophy
L3 Reflexes affected
Knee jerk sluggish, PKB positive, pain on full SLR
L3 paresthesias
Medial knee, anterior lower leg
L4 dermatome
Meidal buttock, lateral thigh, medial leg, dorsum of foot, big toe
L4 myotome (Muscle weakness)
Tibial is Anterior, extensor Hallucis
L4 reflexes affected
SLR limited, neck flexion pain, weak or absent knee jerk, side flexion limited
L4 paresthesias
Medial aspect of calf and ankle
L5 dermatome
Buttock, posterior and lateral thigh, lateral aspect of leg, dorsum of foot, medial half of sale, first, second, and third toes
L5 myotome (muscle weakness)
Extensor hallucis, peroneals, gluteus medius, dorsiflexors, hamstrings and calf atrophy
L5 Reflexes affected
SLR limited one side, neck flexion painful, decreased ankle, crossed-leg raising pain
L5 paresthesias
Lateral aspect of leg, medial three toes
S1 dermatome
Lateral and plantar aspect of foot
S1/S2 myotome (muscle weakness)
Calf and hamstrings, washing of gluteals, peroneals, plantar flexors
S1/S2 Reflexes affected
SLR limited, Achilles reflex weak or absent
S1 paresthesias
Lateral two toes, lateral foot, lateral leg to knee, plantar aspect of foot
S3 dermatomes
Groin, posteromedial thigh to knee
S4 dermatomes
Perineum, genitals, lower sacrum
S4 myotomes (muscle weakness)
Bladder, rectum
S4 parasthesia
saddle area, genitals, anus, impotence, massive posterior herniation
S2 dermatome
Buttocks, thigh, and posterior leg
S2 parathesia
Lateral leg, knee, heel