Dermatomes and Myotomes of the Upper Limb Flashcards
What is a dermatome?
A dermatome is an area of skin supplied by sensory fibers from a single spinal nerve.
What is a myotome?
A myotome is a group of muscles primarily innervated by motor fibers from a single spinal nerve.
How are dermatomes of the upper limb organized?
Upper limb dermatomes are arranged in a segmental pattern from the neck down to the fingers.
How are myotomes of the upper limb organized?
Upper limb myotomes are arranged proximally to distally, corresponding to specific spinal levels.
Which spinal nerves contribute to the dermatomes of the upper limb?
The dermatomes of the upper limb are supplied by spinal nerves C3-T2.
Which spinal nerves contribute to the myotomes of the upper limb?
The myotomes of the upper limb are supplied by spinal nerves C5-T1.
What is the dermatome distribution of C3 and C4 in the upper limb?
C3 and C4 supply the skin over the shoulder and base of the neck.
What is the dermatome distribution of C5 in the upper limb?
C5 supplies the skin over the lateral shoulder and upper arm.
What is the dermatome distribution of C6 in the upper limb?
C6 supplies the lateral forearm and thumb.
What is the dermatome distribution of C7 in the upper limb?
C7 supplies the middle finger and central palm.
What is the dermatome distribution of C8 in the upper limb?
C8 supplies the little finger and medial forearm.
What is the dermatome distribution of T1 in the upper limb?
T1 supplies the medial side of the forearm and lower arm.
What is the dermatome distribution of T2 in the upper limb?
T2 supplies the medial upper arm and axillary region.
Which spinal level is tested by sensory examination over the lateral shoulder?
C5 is tested by sensory examination over the lateral shoulder.
Which spinal level is tested by sensory examination over the lateral forearm and thumb?
C6 is tested by sensory examination over the lateral forearm and thumb.
Which spinal level is tested by sensory examination over the middle finger?
C7 is tested by sensory examination over the middle finger.
Which spinal level is tested by sensory examination over the little finger?
C8 is tested by sensory examination over the little finger.
Which spinal level is tested by sensory examination over the medial forearm?
T1 is tested by sensory examination over the medial forearm.
Which spinal level is tested by sensory examination over the medial arm?
T2 is tested by sensory examination over the medial arm and axilla.
What is the main myotome responsible for shoulder abduction?
C5 is the primary myotome responsible for shoulder abduction (deltoid, supraspinatus).
What is the main myotome responsible for elbow flexion?
C6 is the primary myotome responsible for elbow flexion (biceps brachii, brachialis).
What is the main myotome responsible for elbow extension?
C7 is the primary myotome responsible for elbow extension (triceps brachii).
What is the main myotome responsible for wrist extension?
C6 is the primary myotome responsible for wrist extension (extensor carpi radialis longus and brevis).
What is the main myotome responsible for wrist flexion?
C7 is the primary myotome responsible for wrist flexion (flexor carpi radialis and ulnaris).
What is the main myotome responsible for finger flexion?
C8 is the primary myotome responsible for finger flexion (flexor digitorum profundus and superficialis).
What is the main myotome responsible for finger extension?
C7 is the primary myotome responsible for finger extension (extensor digitorum).
What is the main myotome responsible for finger abduction?
T1 is the primary myotome responsible for finger abduction (dorsal interossei).
How can dermatomes be clinically tested?
Dermatomes are tested using light touch or pinprick sensation on specific skin regions.
How can myotomes be clinically tested?
Myotomes are tested by assessing muscle strength in movements associated with each spinal nerve level.
What is the significance of dermatomal and myotomal testing in diagnosing nerve root lesions?
Dermatomal and myotomal testing helps localize nerve root compression or injury in spinal cord disorders.
