Nerve and Blood Supply of the Back Flashcards
What is the conus medularis and where does it end ?
The conical distal end of the spinal cord
Ends between L1 and L2
What are the enlargements of the spinal cord and what plexuses do they supply?
Cervical enlargement supplies brachial plexus
Lumbar enlargement supplies lumbar sacral plexus
What is Bell m
Magendis law?
Sensory information in through the dorsal horn and roots of the spinal nerves
Motor commands out through ventral horn and roots of spinal nerves
How many spinal nerve pairs are there at each level of the spine?
Cervical- 8
Thoracic-12
Lumbar- 5
Sacral- 5
Coccygeal- 1
Spinal nerves are usually named for the vertebrae above, except…
C1 through C8 which exit above the vertebrae of the same name, so are named for the vertebrae below them
Except C8 which is just weird
(C1 exits above the C1 vertebra between occiput and Atlas)
Where do spinal nerves emerge from?
Intervertebral foramen
Spinal nerves are very short and divide into dorsal and ventral Rami. What else branches off from the spinal nerve?
The meningeal branch which arises in the intravertebral foramen and supplies motor and sensory innervation to the menenges and dorsal side of the intervertebral disc
What did the dorsal and ventral Rami supply respectively?
Which is larger?
Dorsal Rami:
Smaller
Deep intrinsic back muscles
Cutaneous sensations from the back
Ventral Rami:
Larger
Muscles of anterior torso, head and extremities
Extrinsic back muscles
What do the motor and sensory branches of the dorsal rami do?
Motor: intrinsic back muscles
Sensory: cutaneous sensations of the back
With the dorsal rami divide into medial and lateral branches. Which branches are cutaneous + motor, and which are only motor?
Medial branches
t6 & up: motor and cutaneous sensations
T6 & down: only motor
Lateral branches:
T6 & up: only motor
T6 & down: motor and cutaneous sensations
Which dorsal Rami do not split?
C1
S4 and S5 (end of sacrum)
Coccygeal
The medial branch of dorsal Rami provide cutaneous supply in cervical segments. What are the exceptions to this rule? Why?
C1: dorsal Rami does not Branch into medial and lateral
C6, C7, C8: No cutaneous supply
(C2 through C5: motor and sensory)
What is the name of the C1Dorsal Rami?
What is unique about it? What does it supply?
The Suboccipital nerve
Does not split, dorsal ramus is larger than ventral ramus
Supplies muscles of the suboccipital triangle
(Rectus capitus posterior major and minor, obliquis capitus, superior and inferior)
What is the name for the C2 Dorsal ramus? What does it supply?
Is it larger or smaller than the ventral ramus of C2?
The greater occipital nerve
Sensory to the back of the scalp, motor to intrinsic neck muscles
Dorsal ramus is larger
