Dermatomes and myotomes Flashcards
What does the sclerotome give rise to
Vertebrae and ribs
What forms the dermatomyotome
Dorsal surface of somites
What does the dermatomyotome give rise to
Dermis and muscle
What is a neural level
Neural segment of the CNS
Development of DMT Innervation
DMT develops in association with a specific neural level and takes nerve supply from the neural tube with it as a spinal (segmental) nerve
What are spinal nerves
Parallel bundles of motor and sensory axons encased in CT
What divides CNS and PNS
Intervertebral foramen
This marks termination of spinal nerves
How many spinal nerves exist
31 pairs
How are spinal nerves named
According to level of vertebral column from which it emerges
What do spinal nerve roots connect
Each spinal nerve to a segment of the spinal cord
What do dorsal and ventral roots contain
Dorsal - afferent nerve fibres
Ventral - efferent nerve fibres
What is the dorsal root ganglion
Collection of cell bodies of afferent neurones in the PNS
Where does the spinal cord run from and to
Start - inferior margin of medulla oblongata
End - conus medullaris at L2
Where do the long roots of lumbar sacral and coccygeal segments descend before exiting at respective intervertebral foramina
Cauda equina
Where do C1 spinal nerves emerge
Between occipital bone and atlas
Where do C2-7 spinal nerves emerge
Above their corresponding vertebrae
Where does C8 spinal nerve emerge
Between vertebrae of C7 and T1
Where do T1-L5 spinal nerves emerge
Below their corresponding vertebrae
Where do S1-4 spinal nerves emerge
Via 4 pairs of sacral foramina
Where do S5 and Co1 spinal nerves emerge
Via sacral hiatus
What do spinal nerves divide into
Posterior and anterior rami
Meningeal branch
What does the posterior rami supply
Deep muscles and skin of dorsal trunk
What does the anterior rami supply
Muscles and skin of limbs, lateral trunk and ventral trunk
Course of meningeal branch of spinal nerves
Re-enters spinal canal through intervertebral foramina
What do the meningeal branches of spinal nerves supply
Vertebrae
Ligaments
BVs
Meninges
What’s an axial line
Junction between 2 adjacent dermatomes that are supplied from discontinuous spinal levels
What axial lines do limbs have
Anterior and posterior
What do axial lines mark
Centre of either the pre-axial or post-axial compartments of limbs
What are the boundaries of pre and post axial compartments marked by
Veins
Definition of dermatome
Strip of skin supplied by a single spinal nerve that can be examined clinically
Definition of myotome
Group of muscles innervated by a single spinal nerve that can be examined clinically
What is a peripheral nerve territory
Area of skin supplied by a single peripheral nerve
Within a peripheral nerve there may be fibres from more than 1 spinal nerve
What’s the scientific name for shingles
Herpes zoster
Why does herpes zoster affect one dermatome
Chickenpox virus travels through a cutaneous nerve and remains dormant in a dorsal root ganglion
When host is immunosuppressed, the virus reactivates and travels through a peripheral nerve to the skin of a single dermatome
What forms the sclerotome
Ventral surface of somites
What is the neural level of injury
Lowest level of full sensation and function
Spinal roots responsible for lateral rotation of shoulder
C5
Spinal roots responsible for medial rotation of shoulder
C6-8
Spinal roots responsible for Flexion at shoulder
C5
Spinal roots responsible for extension at shoulder
C6-8
Spinal roots responsible for abduction at shoulder
C5
Spinal roots responsible for adduction at shoulder
C6-8
Spinal roots responsible for supination
C6
Spinal roots responsible for pronation
C7-8
Spinal roots responsible for Flexion at elbow
C5-6
Spinal roots responsible for extension at elbow
C6-7
Spinal roots responsible for Flexion at wrist
C6-7
Spinal roots responsible for extension at wrist
C7-8
Spinal roots responsible for abduction and adduction of digits
T1
Spinal roots responsible for extension of fingers
C7-8
Spinal roots responsible for Flexion of fingers
C6-8
Spinal roots responsible for lateral rotation at hip
L5 and S1
Spinal roots responsible for medial rotation at hip
L1-3
Spinal roots responsible for adduction at hip
L1-3
Spinal roots responsible for abduction at hip
L5 and S1
Spinal roots responsible for Flexion at hip
L2-3
Spinal roots responsible for extension at hip
L4-5
Spinal roots responsible for Flexion at knee
L5 and S1
Spinal roots responsible for extension at knee
L3-4
Spinal roots responsible for dorsiflexion
L4-5
L5 and S1 for metatarsophalangeal and interphalangeal joints
Spinal roots responsible for plantarflexion
S1-2
Spinal roots responsible for eversion
L5 and S1
Spinal roots responsible for inversion
L4-5
