Lecture 10: Spinal cord, brain stem, diencephalon, cerebellum Flashcards
(108 cards)
Rostral
Toward the nose
Caudal
Toward the tail
Spinal cord functions
Attach spinal nerves; sensory and motor innervation of body below the head; two-way conduction pathway; major center for reflexes
Spinal cord location
Through vertebral canal of vertebral column through successive vertebral foramina; foramen magnum at base of skull to level of L3 in infants and L1 or L2 in children and adults
Conus medullaris
Inferior end of spinal cord tapers into this
Filum terminale
Long filament of connective tissue extending from conus medullaris down to coccyx inferiorly, anchoring spinal cord in place
Cauda equina
Collection of spinal nerve roots in inferior end of the vertebral canal
Cervical and lumbar enlargements
Where nerves for upper and lower limbs arise
Spinal nerves
31 pairs of spinal nerves (PNS); 8 cervical, 12 thoracic, 5 lumbar, 5 sacral, 1 coccygeal
Spinal cord segments
Indicate region of spinal cord where spinal nerve fibers emerge; since spinal cord does not extend to end of spinal column, spinal cord segments are located superior to where corresponding spinal nerves emerge (e.g., spinal cord segment T5 is located at level of vertebra T4 and spinal cord segment S1 is located at level of vertebra L1)
Spinal cord deep grooves
Wider laterally than anteroposteriorly; two deep grooves run length of cord and partly divide it into right and left halves; dorsal (posterior) median sulcus and wider ventral (anterior) median fisure
White matter
Outer region of spinal cord; composed of myelinated axons as well as unmyelinated axons (fibers)
White matter funiculi
White matter on each side of spinal cord is divided into funiculi (“long ropes”); dorsal (posterior) funiculus; ventral (anterior) funiculus; lateral funiculus
Fibers in white matter
Ascending fibers: carry sensory information to brain; descending fibers: carry motor information from brain to spinal cord; commissural fibers: carry information from one side to the other; commisure: bundle of axons that crosses from one side of the CNS to the other
Gray matter
Shaped like “H” or a “butterfly”; gray commisure (cross-bar of the H): unmyelinated axons and contains narrow central cavity; dorsal horns (posterior arms of H); ventral horns (anterior arms of H); lateral horns: small lateral columns in thoracic and superior lumbar segments of spinal cord
Dorsal root ganglia
Sensory neuron cell bodies lie outside in this
Dorsal roots
Sensory neuron axons reach spinal cord via this
Dorsal horn interneurons
Receive information from sensory neurons
Ventral and lateral horns
Contain cell bodies of motor neurons and interneurons; send axons out of spinal cord via ventral roots; largest in cervical and lumbar segments of the cord
Paralysis
damage to ventral horn or ventral motor roots destroys motor neurons
Paresthesia
Damage to dorsal horn or sensory neuron cell bodies in dorsal root ganglia - loss of sensory function
Meninges
Connective tissue membranes that lie just external to brain and spinal cord; cover and protect CNS; enclose and protect blood vessels that supply CNS; contain CSF
Epidural space
Fat-rich cushioning space just external to dura mater
Dura mater
Strongest layer of meninges; two layered; Periosteal layer (periosteum): outer layer which attaches to internal surface of skull bones; Meningeal layer: deeper layer which forms external covering of the brain and is continuous with dura mater that surrounds the spinal cord