Spinal Cord segments: Flashcards
- Why do we need a spinal cord?
a. Send info from brain to body and vice versa
b. Sensory info passes to brain
c. Motor output out of brain
d. Coordinate reflexes – responses to stimuli. If within spinal cord itself, not even to brain
- Anatomy of spinal cord
a. In spinal column inside vertebrae in vertebral canal
b. From medulla oblongata in brain stem to the caudal end of the body
c. Not same length as vertebral canal, especially in species with tails
d. Intumescences = fatter parts of the spinal cord
- Protective structures of the spinal cord
a. Vertebral column
b. Space in spinal column: epidural space which is filled with adipose and connective tissue
c. 3 layers of meninges: dura mater outermost, arachnoid mater, sub a space and pia mater that encases tissue
d. Inside layers of meninges = connections between pia mater and arachnoid and dura = donticulate ligaments medially and laterally = suspend spinal cord = doesn’t flop = suspended in dura
- What is found within sub arachnoid space?
a. Blood vessels
b. Cerebral spinal fluid
- External anatomy of the spinal cord
a. Intumescences – thoracic and lumbar
b. Each I gives off a plexus of nerves. Brachial and lumbar plexus
c. Narrows to a point = conus medullaris
d. Spinal cord then narrows to a point, gives off nerves still = cauda equina
e. Pairs of spinal nerves given off
- Internal anatomy:
a. Grey matter “horns” = made up of cell bodies. Found on inside (brain = cortex outside). GM extends all the way through the spinal cord
b. White matter = myelin surrounding axons. Organised into funiculi and fascicles/ tracts
c. Fat in epidural space
d. Dorsal median septum
e. Ventral medium fissure
- Grey matter
a. Cell bodies of incoming sensory info, outgoing motor, interneurons
b. Shape = horns: dorsal and ventral horns
c. Cell bodies in Dorsal horn = mostly sensory nerves because sensory info into spinal cord deos so in dorsal aspect = synapse there
d. Ventral horn = motor info as motor output = from the ventral aspect of the spinal cord
e. Lateral horn thoracolumbar spinal segments = sticky outy bit laterally to spinal horn = sympathetic nervous system cell bodies!
f. Sympathetic nervous system exits CNS from spinal cord from thoracolumbar spinal segments
- What is a spinal cord segment?
a. Divided functionally into segments
b. Define where they are by where their spinal nerve comes from
c. Section of the spinal cord that gives off a pair of spinal nerves = SCS
d. Spinal nerve contains both sensory and motor components:
e. Spinal cord with dorsal root and thickening = dorsal root ganglion, ventral roof at bottom
f. Dorsal root/ ramus
General info about spinal segments
a. Spinal segmetns are all diff sizes
b. First spinal segment is v v small and gives off spinal nerves before (cranial) first cervical vertebrae
c. Pattern continues all the way down until reach thoracic vertebrae as one more cervical spinal segment then cervical vertebrae
d. 7 cervical vertebrae
e. 8 cervical spinal cord segments and so 8 pairs of cervical nerves!
f. So thoracic vertebrae, nerves exit from intervertebral foramen caudal to vertebrae!
g. Size of segments gets bigger as go down cervical vertebrae and then get smaller at thoracic
- Why do we get the cauda equina?
a. Lumbar area spinal cord is shorter than vertebral column
b. Sacral spinal cord segments within lumbar spine! So although give nerves that supply areas caudal to lumbar spinal cord stopped a lot earlier = cauda equina!
c. Nerves travel through dura mater, down vertebral canal until find intervertebral foramen they’re supposed to exit at!
- Where deos spinal cord stop in dog?
a. Lumbar vertebrae 6/7
b. Frenchies, boston terriers, pugs = slightly longer. Terminates at L7, if not even further
- What is the conus medularis
a. Natural tapering of the spinal cord caudal to lumbosacral intumescense
b. Cord narrows down as there is much less tissue to supply down there
- What is the Filum terminale?
a. Fine filament of neural tissue (gilal abd ependymal cells)
b. Does still have meningie (dura mata)
c. Anchors itself to one of the tail vertebrae, helps to suspend sheath of meningies within vertebral canal
- What spinal cord segments supply each anatomical region: Cervical, Thoracic, Lumbar, Sacral, Caudal. 2. Name the functional region, area supplied and spinal cord segment
a. Cervical: NECK = C1-C5
b. Thoracic: Cervical intumescence = thoracic limb = C6-T2
c. Lumbar: Thoracolumbar = thorax and abdomen = T3 – L3
d. Sacral: Lumbosacral intumescence = pelvic cavity, pelvic limb and perineum = L4-S3
e. Caudal: Tail = Cd1-Cd5
- What is an intumescence and name the ones in the canine
a. Subtle enlargement of the spinal cord
b. Cervical = C6 to T2 nerves = Thoracic limbs
c. Lumbosacral = L4 to S3 = Pelvic limbs
- What are plexi
a. Dorsal and ventral branches of spinal nerves connect with enighbours to form continuous dorsal and ventral networks
b. Brachial plexus = C6 to T2 nerves
c. Lumbosacral plexus = L4 to S3
- What do the “horns” in the intumescences look like which is different to other parts of the spinal cord and why is this?
a. Ventral horn of the grey matter is larger than the dorsal
b. Because ventral horn contains motor cell bodies = supplying limbs
c. Need more motor cell bodies here as lot of complex muscles in limbs to supply
- How is white matter organised?
a. In tracts
b. Sensory nerve tracts from skin and musculoskeletal system to cerebral cortex
c. Motor nerves tracts from cerebral cortex to skeletal muscles
- How are tracts arranged in the spinal cord?
a. Into FUNICULUS = a region containing different bundles of nerve fibres/ acons
b. Dorsal funiculus = sensory tracts
c. Lateral funiculus= mixed sensory and motor tracts
d. Ventral Funiculus = mixed sensory but MORE motor tracts
e. Within each funiculus = FASICULUS = a bundle of the same anatomical nerve fibres/ axons that make up a tract
f. Many fascicles are contained within a funiculus
- Spinal reflexes
a. Don’t require input or output from the brain
- What is a dermatome
a. Belt like sections of skin that are supplied by a given spinal nerve
