Spinal Cord, Nerves & Blood Supply Flashcards
Spinal Cord (+ functions)
Relays information to and from the brain, performs some integrative activities (reflexes), originates from the base of the skull (foramen magnum), spinal cord ends at 1st lumbar vertebra
Spinal Nerves
Bundles of axons connected to the spinal cord, nerves exit the vertebral canal at the end level of the origin and destination, form nerve plexuses that innervate skin and skeletal muscles
Innervate
Provide nerves to
Cervical Spinal Nerves
Innervates neck and diaphragm muscles
Brachial Spinal Nerves
Innervates pectoral girdles and upper limbs
Lumbosacral Spinal Nerves
Innervates pelvic girdle and lower limbs
Cauda Equina
The end of the spinal cord, the remaining nerves of the spinal cord extend inferiorly and resemble a horse tail
Make-up of Peripheral Nerve
Axons are surrounded by endoneurium -> bundles of axons are called fascicles -> fascicles are surrounded by perineurium -> collective fascicles, blood vessels, and other connective tissues are surrounded by epineurium
Precentral Gyrus
Anterior to the central sulcus, controls voluntary movement, pre-motor cortex - planning of movement
Postcentral Gyrus
Posterior to central sulcus, receives sensory information
Spinothalamic
Basic sensory pathway
Corticospinal
Motor pathway
Reflex Pathway
Integration in spinal cord
The Brain and Spinal Cord are Protected from Mechanical Forces by:
Cranial bones & vertebrae, meninges, cerebrospinal fluid (CSF)
Three Layers of Meninges
Dura mater, arachnoid mater, pia mater
Dura Mater
Outermost layer of meninges, fibrous layer that is fused to the periosteum
Arachnoid Mater
Middle layer of the meninges, smooth membrane that covers the brain and spinal cord, contains blood vessels (subarachnoid space - contains blood vessels and cerebrospinal fluid)
Pia Mater
Delicate tissue layer of the meninges adhered to the surface of the brain and the spinal cord
Dural Folds (in the Dura Mater)
Falx cerebri, tentorium cerebelli, falx cerebelli, dural sinus
Falx Cerebri
Fold of dura mater that projects between the cerebral hemispheres
Tentorium Cerebelli
Separates the cerebral hemispheres from the cerebellum
Falx Cerebelli
Separates the 2 cerebellar hemispheres (in the mid-sagittal line, inferior to the tentorium cerebelli)
Dural Sinus (aka Superior Sagittal Sinus)
Large collecting vein within dural folds
Ventricles
Produced during brain development, filled with cerebrospinal fluid (CSF), lined with specialised cells (ependymal cells)
Cerebrospinal Fluid (CSF)
Constantly produced and maintained within the ventricles in the area called the choroid plexus -> circulates through the ventricles and fills the the central canal of the spinal cord -> enters the subarachnoid space & circulates around the brain, spinal cord & cauda equina -> drained from the subarachnoid space through arachnoid granulations into the dura mater -> absorbed into venous circulation via the superior sagittal sinus
Brain Receives Blood Through the Arch of the Aorta via:
Vertebral artery, internal carotid artery, left and right sides [collectively called the cerebral arterial circle]
Blood-Brain Barrier (BBB)
Isolate the CNS from chemicals and hormones circulating the blood, maintained by astrocytes which wrap around blood vessels
What can go Wrong with Blood Supply to the Brain?
[Blood supply interrupted (cerebrovascular accident), brain cells die due to lack of oxygen, disruption of blood flow (restrict oxygen flow to cells)] - can cause blockages & ruptures (aneurysm)
