Chapter 13 - Spinal Cord
About this set
Created by:
lthekkan on November 20, 2011
Subjects:
anatomy, physiology, spinal cord, nerves
Description:
Exam IV, spinal cord, spinal nerves, somatic reflexes
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68 terms
Terms | Definitions |
|---|---|
 Spinal Cord | Beginning at foramen magnum down to L1/L2 level, ending just below rib cage, as we develop the skeletal system outgrows this |
| Cervical Enlargement of Spinal Cord | Responsible for supplying nerves to the upper limb |
| Lumbar Enlargement of Spinal Cord | Responsible for supplying nerves to the lower limb |
| Conus Medullaris (Medullary Cone) | Pointy ending of spinal cord |
| Cauda Equina | Lower lumbar & sacral nerves travel down vertebral canal & come out at different levels, nerves of spinal cord travel down to form this cluster of nerves (roots) Used to get CSF sample |
| Regions of Spinal Cord | Cervical, thoracic, lumbar, & sacral |
| Meninges | Coverings of the spinal cord |
| Dura Mater | Thick fibrous layer, not attached to vertebrae, layer of adipose tissue between (dura mater of cranium is fused with bones); epidural & subdural spaces |
| Epidural Space | Between dura mater & vertebra, where epidural anesthesia is administered |
| Subdural Space | Between dura mater & arachnoid mater |
| Arachnoid Mater | Not as tough/thick as dura mater, contains fibers extending & attaching to the deeper surface which form a mesh like spider web; subarachnoid space |
| Subarachnoid Space | Between arachnoid & pia mater, contains CSF |
| Pia Mater | Innermost meninges, deepest, & most delicate; follows all contours of spinal cord (sits right on top of it), forms some lateral extensions from the spinal cord when they travel laterally & attach to the sides of the vertebral column; denticulate ligaments & filum terminale |
| Denticulate Ligaments | Extensions from the pia mater that anchor the spinal cord to the vertebral canal laterally, limits the side-to-side movement of the spinal cord |
| Filum Terminale | Extension below conus medullaris & forming a thin fibrous cord |
| Fissure | Large depression |
| Sulcus | Shallow depression |
| Gyrus | Raised area |
| Anterior Median Fissure | Anteriorly located large depression in midline |
| Posterior Median Sulcus | Shallow depression located posteriorly in spinal cord |
| Central Canal | Lined by ependymal cells containing CSF (both here & subarachnoid space) |
| Gray Matter | Dark area in center that looks like an "H", made up of cell bodies, dendrites, & unmyelinated axons |
| Gray Matter Horns | Connected in center by gray commissure, posterior, lateral (not present in all sections but in thoracolumbar area), & anterior _____ |
| White Matter | Myelinated axons, surrounding the gray matter; funiculi (white columns) & tracts |
| Funiculi (White Columns) | Anterior, posterior, & lateral ________, white areas of spinal cord |
| Spinal Tracts | Collection of axons in spinal cord, myelinated, white in appearance, cross over to opposite side (left controls right, vice versa) |
| Ascending Tracts | Tracts that go up to the brain (afferent/sensory tracts b/c they take information to the brain), 3 neuron composition: 1st Order, 2nd Order, 3rd Order |
| 1st Order Neuron | Neuron soma located in dorsal root ganglia, part of ascending tracts |
| 2nd Order Neuron | Neuron soma located in spinal cord/medulla, part of ascending tracts |
| 3rd Order Neuron | Neuron soma located in thalamus, part of ascending tracts |
| Descending Tracts | Tracts that carry information from the brain, down the cord (motor tracts), pyramidal (direct); 2 neuron composition: upper & lower motor |
| Upper Motor Neuron | Located in cerebral cortex (precentral gyrus), part of descending tracts |
| Lower Motor Neuron | Located in medulla/spinal cord, part of descending tracts |
| Spinal Nerve | Nerve which comes off the spinal cord, collection of axons in PNS |
| Composition of Spinal Nerve | Endoneurium, fascicle, perineurium, epineurium |
| Endoneurium | Connective tissue covering around single axons |
| Fascicles | Containing myelinated & unmyelinate nerve fibers, bundles of axons |
| Perineurium | Connective tissue covering bunches of fascicles |
| Epineurium | Connective tissue covering around spinal nerve |
| Spinal Nerve Formation | Comes off spinal cord & is formed by fibers, roots, spinal nerve |
| Anterior/Ventral Root | (Motor fibers) autonomic fibers come out & make a connection to sympathetic ganglia |
| Posterior/Dorsal Root | (Sensory fibers) contains dorsal root ganglia (neurosomas of sensory neurons) |
| Rami | Part of spinal nerve that supplies various parts of the body (AKA distal branches) |
| Anterior/Ventral Ramus | Complex distribution, separated as either T2 to T12 or all other ventral rami |
| T2 to T12 Rami | Stay independent, separate, form intercostal & subcostal nerves, wrap around torso & supply surrounding areas |
| "Other" Ventral Rami | Mix together, form plexuses (network of interconnecting nerves) |
| Cervical Plexus | Origin: C1 to C5 & branch from C5 Nerve: phrenic nerve, supplies diaphragm, "C3 4 5 keeps the diaphragm alive" |
| Brachial Plexus | Origin: from ventral rami of C5 to T1 (root, trunk, anterior & posterior division, cord) Nerves: musculocutaneous = brachialis, biceps brachii, coracobrachialis axillary = deltoid radial = all back of arm, forearm, extensors of arm & wrist median = flexors of forearm & lateral portion of hand ulnar = skin of palm, medial hand, digits "Real Tired, Need Coffee" |
| Lumbar Plexus | Origin: L1 to L4 (branch from L5) Nerves: femoral = anterior aspect of thigh obturator = medial side of thigh, adductor muscles |
| Sacral Plexus | Origin: ventral rami L4 (lumbosacral trunk) to S4 Nerves: sciatic nerve (combo of common fibular/peroneal nerve & tibial nerve) = posterior aspect of thigh tibial nerve = posterior aspect of leg, calf common peroneal = lateral & anterior aspect of leg **Lumbosacral plexus = overlap of two plexuses |
| Posterior/Dorsal Ramus | Simplistic distribution; go through posterior part of torso & supply their respective regions on the dorsum of torso (skin & muscles of back); do NOT form plexuses |
| Meningeal Branch | Goes back in to the vertebral canal & supplies the meninges |
| Reflex | Quick, involuntary reactions to a stimulus |
| Autonomic Reflex | Through sympathetic, parasympathetic system (defecation reflex) |
| Somatic Reflex | Through skeletal muscles (knee jerk reflex) |
| Innate Reflex | From birth (suckling reflex) |
| Learned Reflex | Acquired through experiences (using break when driving) |
| Ipsilateral Reflex | Stimulus & response on the same side |
| Contralateral Reflex | Stimulus & response on opposite sides |
| Monosynaptic Reflex | 2 neurons in reflex arc |
| Polysynaptic | More than 2 neurons in reflex arc |
| Reflex Arc | receptor, afferent neuron (sensory neuron), interneuron, efferent neuron (motor neuron), effector |
| Receptor | (sensor) picks up actual stimulus |
| Interneuron | may or may not be present, usually in CNS, present only in polysynaptic (not monosynaptic) |
| Stretch Reflex | Maintains length of muscle (posture) Receptor = muscle spindle, modified muscle cells whose function is nothing but to monitor length of the muscle Send info to antagonistic muscle & inhibits them **ipsilateral reflex |
| Golgi Tendon Reflex | Safety reflex, prevents tearing of muscles & tendons; if a muscle is overly stressed (excessive contraction) it will either pull tendon off bone or tear tendon itself, high amount of stress will stimulate the golgi tendon receptors Receptors = golgi tendon receptors, inhibit the muscles that are contracting Antagonistic muscles are stimulated |
| Flexor Reflex | Safety reflex, pulls away extremity from dangerous stimuli Examples: touch something very hot, let go by pulling extremity away |
| Crossextensor Reflex | Opposite limb will extend Example: when you pull your leg away from something the other limb needs to extend in order to bear the weight **contralateral reflex |
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