Ch 13 14 8 ch 16 Spinal Cord PET 3323 Study Guide Exam 1 Know the basic anatomical structures of the spinal cord and the meningeal layers Basic structures Cervical enlargement C4 T1 nerves to and from upper limbs arise from here Superior Lumbar enlargement T9 T12 Nerves to and from lower limbs inferior Conus medullaris conical structure inferior to lumbar enlargement Ends between L1 and L2 Arising from this is the filum terminale an extension of the pia mater and dura mater anchors spinal cord to coccyx Spinal nerves paths of communication between spinal cord and body regions 31 pairs of spinal nerves energe from intervertebral foramina 8 cervical 12 thoracic 5 lumbar 5 sacral 1 coccygeal Spinal cord extends from medulla to oblongata to the superior border of the 2nd lumbar vertebra In infants it goes to L3 or L4 but at age 4 or 5 spinal cord stops growing and veretebral column keeps growing Roots 2 bundles of axons Connect each spinal nerve to a segment of the cord o Posterior dorsal root have only sensory axons which conduct nerve impulses from sensory receptors in skin muscles and internal organs into CNS Has a swelling posterior root ganglion has cell bodies of sensory neurons o The anterior ventral root have axons of motor neurons which conduct nerve impulses from CNS to effectors muscles and glands Meningeal layers 3 protective CT coverings that encircle the spinal cord and brain 1 dura mater most superficial Strong layer of dense irregular CT 2 arachnoid mater middle layer thin avascular covering of cells and thin loosely arranged collagen elastic fibers Subdural space is between arachnoid and dura has interstitial fluid 3 pia mater deepest Thin layer CT adheres to spinal cord and brain surface Contains vessels to supply oxygen and nutrients to spinal cord Subarachnoid space is between arachnoid and pia it has shock absorbing cerebrospinal fluid Spinal meginges surround cranial meninges which encircle brain Also protected by fat and CT located in epidural space Know where anterior horn posterior horn etc are Know what area of the spinal cord a lumbar puncture will be performed and why Lumbar puncture aka spinal tap Long hollow needle inserted into the subarachnoid space to withdraw cerebrospinal fluid Patient lies on side with vertebral column flexed flexing increases distance between spinous processes Spinal cord ends around L2 but spinal meninges and circulating cerebrospinal fluid extend to S2 So spinal tap is usually performed between L3 and L4 or L4 and L5 cus the region provides safe access to subarachnoid space without risk of damaging spinal cord Distinguish between white and gray matter i e location divisions of each what is each made up of etc White Matter has myelin and neural processes Primarily composed of myelinated axons Surrounds inner core of gray matter Communicates with CNS o Anterior median fissure and posterior median sulcus anterior is a wide groove and posterior is a narror furrow o Columns divided like horns of gray matter Have bundles of axons called tracts have axons that conduct nerve impulses toward Sensory ascending tracts Motor descending tracts Transverse tracts one side of the cord to the other axons that carry nerve impulses from the brain Gray Matter H shape in center More cell bodies and unmyelinated fibers Has neuronal cell bodies dendrites unmyelinated axons axon terminals and neuroglia o Grayish in color cus of Nissl bodies and little to no myelin o In brain thin shell of gray matter covers surface of the largest portions of the brain the cerebrem and cerebellum o Gray commissure forms crossbar of the H shape Center of this is the central canal goes entire length of spinal cord and has cerebrospinal fluid o Horns the brain Posterior gray horn contains cell bodies and axons of interneuron s as well as axons of incoming sensory neurons Interneuron s or associated neurons lie between motor and sensory neurons in neural pathways and shuttle signals through CNS pathways where integration occurs From sensory to motor afferent to efferent Anterior gray horns have somatic motor nuclei Provide nerve impulses for contraction of skeletal muscles Efferent neurons AWAY from CNS Lateral gray horns between other 2 Only in thoracic and upper lumbar segments Have autonomic motor nuclei regulate activity of cardiac muscle smooth muscle and glands Sends efferent info to visceral organs AWAY from CNS Ventral roots Amount gray matter most in cervical and lumbar segments cus they are responsible for sensory and motor innervation of the limbs More sensory and motor tracts present in upper segs of spinal cord SO amt of white matter decreases from cervical to sacral cus 1 as cord ascends more ascending axons are added to spinal cord white matter to form more sensory tracts 2 as cord descends motor tracts decrease in thickness as more descending axons leave motor tracts to synapse w neurons in gray matter Blood vessels present in both Know the various parts contents of the gray matter and the types of information that are processed by each area e g dorsal ventral and lateral horns dorsal root ganglion Dorsal Horns receive afferent info to brain from body Contain cell bodies and axons of Interneurons and incoming sensory neurons dorsal roots more above Ventral horns somatic motor neurons send efferent info to skeletal muscle largest in cervical and lumbar regions ventral roots Provide impulses for contraction of skeletal muscles more above Lateral horns autonomic motor neurons sends efferent info to visceral organs only present in thoracic and superior lumbar regions ventral roots Regulate activity of cardiac muscle smooth muscle and glands autonomic motor neurons do that more above Dorsal root ganglion has cell bodies of sensory neurons afferent going in Swelling of posterior root Same qualities as dorsal horns Know the basic characteristics of white matter tracts White matter myelinated and unmyelinated nerve fibers that allow communication between parts of the spinal cord and between cord and brain Ascending descending transverse below o Ascending sensory input UP to brain o Descending motor input from brain DOWN to where its going o Transverse from side of cord to the other Know the nonspecific specific and spinocerebellar pathways and the type of information processed through each Nonspecific ascending pathways lateral and anterior spinothalamic Nonspecific Info regarding pain temperature coarse touch and pressure think cant be specific about the info I
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