Spinal Cord and Meninges Flashcards
Visceral vs. somatic
Visceral - smooth and cardiac muscle
Somatic - Body walls and limbs
How do brain and spinal cord connect?
Foramen magnum of the occipital bone of the scull
How far down does spinal cord exten?
L1-L2
How many spinal nerves associated with each spinal cord level?
2
How are spinal nerves named?
In cervical, named for vertebra inferior to exit
Everywhere else, named for vertebra superior to exit
C8 is below C7
More inferior nerve fibers are _______ and _____
longer and more vertical
Conus Medullaris
Narrowing of spinal cord at the sacral and coccygeal spinal cord levels
Cauda equina
Dorsal and ventral roots of inferior segments that travel until they can reach their respective intervertebral foramen
Filum terminale
Extension of the pia mater which covers the spinal cord from the conus medullaris to the coccyx
Passes through cauda equina and pierces dura mater to attach to the coccyx
White matter found where and composed of what?
Outer region
Myelinated axons
Grey matter found where and composed of what and shape?
Inner region
H shape
Composed of neuronal and glial cell bodies
Glial cells
Supporting cells for neurons
Gray matter divided into
Anterior (ventral) horn and Posterior (dorsal) horn
Ventral horn
Contains somatic motor neurons that innervate skeletal muscles
Dorsal horn
Contains neurons that receive sensory information from spinal ganglia neurons
ventral root and where it originates
Motor fibers that innervate somatic muscles
Originate from anterior horn neurons
Dorsal Root and where it originates
Somatic Sensory fibers from periphery to the CNS. Originate from spinal ganglion neurons located external to the spinal cord
Spinal ganglion and location
Collection of nerve cell bodies outside of the CNS
No synapses here
Located in intervertebral foramen
Unipolar neurons that have processes ending in dorsal horn
Peripheral processes associated with a sensory receptor
Spinal Nerve and 2 branches
Relatively short structure that is formed by union of ventral root and dorsal root
Dorsal primary ramus and ventral primary ramus
Dorsal primary ramus innervations
Innervates epaxial muscles and overlying skin
Ventral primary ramus innervations
Hypaxial muscles and overlying skins (everything but true back muscles)
Rami and Roots…which are mixed in function and whic are not?
Roots are not
Rami are mixed
Dorsal root cell bodies lie _____
in spinal ganglion
Ventral root cell bodies lie _____
in ventral horn
Three layers of connective tissue that cover spinal cord
Dura Mater
Arachnoid Mater
Pia Mater
Dura mater and how far does it extend?
External outer tough covering that extends to S2 levels of vertebral canal
Extends to the distal end of the spinal ganglion
What does dura mater become continuous with
Epineurium of spinal nerves
Dural sleeves
Extensions of Dura mater
Dural Sac
Blind end pouch of dura mater that extends to S2 vertebral levels
Arachnoid mater and how far does it extend?
Avascular membrane deep to the dura mater
Follows the dura mater
Pia mater
Deepest layer. Adherent to spinal cord
Denticulate ligaments
Lateral extensions of the pia mater which help anchor the spinal cord to dura mater
Run through the arachnoid and into dura mater
How can you tell sepration between various ventral and dorsal roots
denticulate ligaments in between
Epidural space
Lies superficial to dura mater
Contains fat and internal vertbral venous plexus
Internal vertebral venous plexus
Drains spinal cord
Is there epidural space in cranium?
No
Subarachnoid space
Lies deep to arachnoid membrane but superficial of pia
Contains CSF
Exists in cranium
What is CSF produced by?
Choroid plexus in ventricles of the brain
Anesthesia above L4
Go into the subarachnoid space - spinal
Anesthesia below L4
Stop before you hit dura mater - epidural
Dermatome
Area of skin supplied by one spinal cord level
50% overlap
Three levels lost before deficit apparent
Dermatomes we need to know
T4 - areola
T10 - umbilicus
L1 - lower extent of trunk
Cutaneous innervation
Area of skin innervated by a peripheral nerve which may or may not have more than one spinal cord level within it
Spinal cord receives blood supply from
Anterior spinal artery and posterior spinal arteries
Size of spinal arteries as they move down
Decrease
Segmental arteries and two types
Supplement spinal arteries at each vertebral level
Medullary and Radiclar
Medullary arteries
Extend into the spinal cord and anastomose with the longitudinal arteries to receive their supply
Radicular arteries
Supply the dorsal and ventral roots that aren’t supplied by segmental arteries
Arteries in each spinal region
Lumbar arteries
Posterior intercostal arteries
Vertebral, ascending cervical, or deep cervical
