Dermatomes + Myotomes Flashcards
(42 cards)
What are spinal nerve roots?
Roots connect each spinal nerve to a segment of the cord
What do dorsal roots carry?
Afferent/sensory fibres
What do ventral roots carry?
Efferent/motor fibres
Autonomic fibres
How many pairs of spinal nerves are there?
31
Where does the spinal cord start?
Medulla oblongata
Where does the spinal cord end?
Conus Medullaris at L2
What is the cauda equina?
Descending spinal roots from below L2
Where do C1-7 exit in relation to their vertebrae?
Above the vertebrae
Where does C8 exit in relation to vertebrae?
Between C7 and T1
Where do T1-L5? exit in relation to vertebrae?
Below the vertebrae
Where do S1-4 exit in relation to vertebrae?
Exit via 4 pairs of sacral foramina
Where do S5 and Co1 exit in relation to vertebrae?
Exit via sacral hiatus
What is a ramus?
Mixed spinal nerves divide into rami
What is supplied by the posterior/dorsal ramus?
Deep muscles
Skin of dorsal trunk
What is supplied by the anterior/ventral ramus?
Muscles + skin of limbs
Lateral trunk
Ventral trunk
What is supplied by the rami communicantes?
Components of the autonomic system
What is supplied by the meningeal branch of spinal nerves?
Vertebrae
Ligaments
Blood vessels
Meninges
What happens to the dorsal/posterior rami?
Divides into medial and lateral branches
Supplies skin of back in segmental manner
What happens to the ventral/anterior rami?
Segmental for the trunk
Enter the plexuses to supply the limbs
What is a dermatome?
Area of skin supplied by a single spinal nerve
What is a myotome?
Group of muscle supplied by a single spinal nerve
What is the axial line?
Junction of 2 dermatomes supplied from discontinuous spinal levels
What do axial lines mark?
Centre of ventral or dorsal compartments of the limbs
What is the significance of dermatomes and axial lines?
There is functional overlap between dermatomes but they do not cross axial lines
