Spinal Cord Anatomy and Receptors Flashcards
Where and why does the cervical enlargement occur?
C5-T1, corresponding to nerve roots from the brachial plexus, which innervate the upper limbs.
Where and why does the lumbosacral enlargement occur?
L1-S3- corresponding to nerve roots from the lumbosacral plexus, which innervate the lower limbs.
What is the caudal extent of the spinal cord?
In newborns: L3
In adults: L1/L2
How many spinal nerves are there in an adult, on average.
31 pairs.
Dermatome versus peripheral nerve field:
Dermatome refers to the cutaneous area innervates by fibers from a single dorsal root. Whereas peripheral nerve field, refers to sensory field that may use more than 1 dermatome.
Exceptions: no overlap seen in C2, and trigeminal nerves V1, V2 and V3.
What are some common dermatomal references? (6)
C2 - back of head C6- thumb and index finger T4- nipples T10- umbilicus L3- Kneecap S1- lateral foot
T/F: The white matter and gray matter distribution in the brain and spinal cord are the same throughout.
False.
In the spinal cord, white matter is in the outer edges, gray matter in the inside versus the brain, gray matter is in the outside, white matter is in the inside.
Where do vertebral arteries and nerves travel through?
Vertebral arteries travel through the transverse foramen, nerves exit the intervertebral space.
Where does the dorsal root enter the spinal cord?
Posterior lateral sulcus.
What is located in the anterior median fissure?
The anterior spinal artery.
1 unpaired arterial spinal artery sits in the anterior median fissure, while there are 2 posterior, very wiggly.
Both come off the vertebral artery.
What important structure is in the anterior lateral sulcus?
Ventral/anterior horn exits.
Where in the spinal cord does the dorsal column pathway travel through?
Posterior funiculus
What pathway travels through the lateral funiculus?
The corticospinal tract descends through the lateral funiculus, until synapsing on anterior/ventral horn cells.
What does the dorsolateral fasciculus contains?
AKA: zone of lissauer
Finely myelinated and unmyelinated axons originating in the substantial gelatinosa and involved in sensory modulation.
loc: between posterior and lateral funiculus
What important fibers cross at the anterior commissure?
Many fibers can cross, but in particular, spinothalamic tract cross here after DRG synapses at nucleus proprius and ascend to the thalamus.
What does the base of the alar plate become?
Dorsal horn, involved mostly in sensory/afferent.
What does the base of the basal plate become?
Ventral horn, involved mostly in motor/efferent.
What information does the substantial gelatinosa relay?
small compact cells that modify sensory input by synapsing on the nucleus proprius, and ascending/descending in Lissauer’s tract.
Homologous to the spinal trigeminal nucleus
At all cord levels
What information does the nucleus proprius relay?
"proper sensory nucleus" Receives many sensory inputs. Contains many interneurons Contains "tract cells" that project contralatterally (through ant commissure) as the spinothalamic tract At all cord levels
STT = pain and temp body except head
What information does the nucleus dorsalis is relay?
AKA: Clark’s nucleus
Receives muscle spindle information
Homologous to the lateral/accessory cuneate nucleus in the medulla.
Projects ipsilateral to the cerebellum as the DORSAL spinocerebellar tract.
Where is Clark’s nucleus found?
AKA: Nucleus dorsalis. Found only at C8-L3
Projects ipsilateral to the cerebellum as the DSCT.
Intermediolateral nucleus:
Origin of PREganglionic cholinergic sympathetic efferents
Loc: T1-L3
GVE
Intermediomedial nucleus:
Receives visceral afferents
Projects to the IML
Found at all levels
What does muscle spindles detect?
Muscle length/stretch. Important proprioception.
What does golgi tendon organs detect?
Muscle tension. Internal tension/isometric contraction.
DRG- lateral division
thin, lightly myelinated fibers
pain, temp, light touch, visceral afferents
DRG- medial division
thick, heavily myelinated
2 point touch, limb position, muscle stretch, sends collaterals to medulla
