Corticospinal Tract

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What are the three most important motor and sensory tracts in the CNS?: 1. Lateral corticospinal tract
2. Posterior Columns
3. Anterolateral pathways

Adapted from H. Blumenfeld (2002)
What are the functions of the 1.)Lateral corticospinal tract; 2.)Posterior Columns; and 3.)the Anterolateral pathways: The function of the Lateral corticospinal tract is motor.

The function of the Posterior Columns is Sensory (i.e., vibration, joint position, fine touch.

The function of the Anterolateral pathways is sensory (pain, temperature, crude touch.

Adapted from H. Blumenfeld (2002)
Each of these tracts decussates (i.e., Lateral corticospinal tract; Rubrospinal tract; and Anterolateral pathways), but where, and why is this important?: The descending lateral corticospinal tract deccusates at the cervicomedullary junction. The ascending Rubrospinal tract decussates in the ventral tegmentum at the level of the midbrain to the red nucleus (magnocellular division). A portion of the anterior corticospinal tract decussates at the level of the cervical spinal cord, just below the Pyramid. Knowledge of crossover points is helpful in localizing lesions.

Adapted from H. Blumenfeld (2002)
Another name for the central sulcus is what?: The Rolandic sulcus

Adapted from H. Blumenfeld (2002)
What lies on anterior to the Rolandic sulcus and what is this gyrus called.: The Primary Motor cortex lies anterior to the cental sulcus in the precentral gyrus.
What lies posterior to the Rolandic sulcus and what is this gyrus called?: The Primary Somatosensory Cortex lies posterior to the cental sulcus in the postcentral gyrus.

Adapted from H. Blumenfeld (2002)
What Broadman's area identifies the primary motor cortex in the precentral gyrus?: Broadman's Area: 4

Adapted from H. Blumenfeld (2002)
What Broadman's Area identifies the Primary sensory cortex in the postcentral gyrus: Broadman's Areas: 3, 1, 2

Adapted from H. Blumenfeld (2002)
What important motor association cortex areas lie anterior to the Primary Morot Cortex?: 1.) the Supplementary motor area
2.) the Pre-motor area
What are the the Supplementary motor area and the Pre-motor area involved in and where do they project?: Involved in: Higher order motor planning

Project to: the Primary Morot Cortex

Adapted from H. Blumenfeld (2002)
Can lesions of the Primary Motor Cortex produce severe deficits in basic movement?: YES

Adapted from H. Blumenfeld (2002)
Can lesions of the Primary Somatosensory Cortex produce severe deficits in basic sensation?: YES

Adapted from H. Blumenfeld (2002)
Can lesions of the sensory or motor association cortices produce severe deficits in basic movement or sensation?: NO. Deficits resulting from lesions in the association cortices would be manifest as deficits in higher order sensory analysis or motor planning.

Adapted from H. Blumenfeld (2002)
What kind of connections exist between both primary and association cortices, between the sensory and motor areas?: Reciprocal connections between them all.
What does "Somatotopic organization of primary motor/sensory cortex mean?: Adjacent regions on cortex correspond to adjacent areas on the body surface.

Adapted from H. Blumenfeld (2002)
How have the somatotopically organized sensory and motor maps been classically depicted?: They have been depicted by the "motor homunculus" and the "sensory ".

Adapted from H. Blumenfeld (2002)
"Homunculus" from Latin translated means what?: Little Man
Are somatotopic maps clear-cut and consistent ?: No. High spatial resolution studies have found these maps are not as clear-cut and consistent as originally believed.

Adapted from H. Blumenfeld (2002)
Why use the homunculi representations anyway?: Useful for understanding the broad strokes of cortical representation; Widely used for clinical representation.

Adapted from H. Blumenfeld (2002)
Is somatotopic organization found only in the cortex?: No. Some motor and sensory pathways roughly maintain somatotopic organization their entire length.

Adapted from H. Blumenfeld (2002)
What Broadman's area described the premotor cortex?: Broadman's area: 6

Adapted from H. Blumenfeld (2002)
What Broadman's area describes the Parietal Association cortex: Broadman's areas: 5, 7

Adapted from H. Blumenfeld (2002)
Where is the Secondary somatosensory area?: In the parietal operculum

Adapted from H. Blumenfeld (2002)
Somatotopic Organization: The arms are medial to the legs with what two exceptions?: the primary senorimotor cortices and the posterior comlumns (Figures 6.2; 6.10; and 7.3)

Adapted from H. Blumenfeld (2002)
Basic Anatomy of the Spinal Cord: Simply describe the structural organization of the spinal cord: Centrally located, butterfly-shaped "central gray matter" surrounded by ascending and decending white matter columns (funiculi)

Adapted from H. Blumenfeld (2002)
Basic Anatomy of the Spinal Cord: Where do messages come from/ or go to/ regarding the sensory neurons in the dorsal root ganglia that bifurcate?: 1 branch: incoming sensory information from the periphery

2nd branch:information is carried through dorsal nerve root filiaments into the dorsal aspect of the spinal cord.

Adapted from H. Blumenfeld (2002)
Basic Anatomy of the Spinal Cord: The dorsal (posterior) horn of the central gray matter is involved primarily in: what?: Sensory processing.

Adapted from H. Blumenfeld (2002)
Basic Anatomy of the Spinal Cord: What does the "intermediate zone" of the central gray matter contain?: Interneurons and specialized nuclei

Adapted from H. Blumenfeld (2002)
Basic Anatomy of the Spinal Cord: What does the ventral (anterior) horn of the central gray matter contain?: Motor neurons.

Adapted from H. Blumenfeld (2002)
What path do axons of the motor neurons take(originating in the central gray matter) to send information out of the spinal chord?: Motor neurons axons exit the central gray matter via the "Ventral Nerve Root Filiaments", traverse the lateral column, continue in the "Ventral Root" (motor), and continues on its' outgoing path as the part of the "Spinal Nerve" (coupled with incoming sensory axons)

Adapted from H. Blumenfeld (2002)
How has the spinal gray matter been divided into nuclei by Bror Rexed: Rexed's laminae: Progressing dorsally to ventrally, then laterally to centrally, laminae are labeled: I; II; III; IV; V; VI; VII; VIII; IX; and X

Adapted from H. Blumenfeld (2002)
What are 10 important nuclei and nuclei areas named in the gray matter (represented bilaterally)?: Progressing dorsally to ventrally, then laterally to centrally,these nuclei are - in the Dorsal Horn Region: "Marginal zone" (Rexed I); "Substantia gelatinosa"(Rexed II); "Nucleus proprius"(Rexed III, IV); "Neck of Dorsal Horn" (Rexed V); "Base of Dorsal Horn" (Rexed VI). In the Intermediate Zone region- "Clarkes nucleus" & the "Intermediolateral nucleus"(Rexed VII). In the Ventral Horn: the "Commissural nucleus" (Rexed VIII); "Motor Nuclei" (Rexed IX). In the region of Gray mattersurrounding the central canal: Grisea Centralis (Rexed X).

Adapted from H. Blumenfeld (2002)
How is the spinal cord white matter organized?: Into columns: Dorsal (posterior) columns; Lateral Columns; and Ventral (anterior) columns. See Fig. 6.3A)

Adapted from H. Blumenfeld (2002)
What is the make-up of the spinal cord at the cervical levels and the significance of this make-up?: Cervical spinal cord: White matter is thickest, i.e., Most ascending fibers have already entered the cord; most decending fibers have yet to terminate on targets

Adapted from H. Blumenfeld (2002)
What are the two areas of enlargement in the spila cord called?: The cervical enlargement & the lunbosacral enlargement.

Adapted from H. Blumenfeld (2002)
What does the cervical enlargement & the lunbosacral enlargement give rise to?: The nerve plexuses for the arms and legs.

Adapted from H. Blumenfeld (2002)
Where is spinal chord gray matter the greatest? ... the least?: Gray matter is greatest in the cervical and lumbosacral areas. Least at the thoracic levels, particularly the ventral horns (lower motor neurons for arms and legs here). Thoracic cord has a lateral horn with an intermediolateral cell column

Adapted from H. Blumenfeld (2002)
From where does the spinal chord get it's blood?: Spinal chord blood comes from branches of the:
vertebral arteries &
spinal radicular arteries

Adapted from H. Blumenfeld, Neuroanatomy Through Clincal Cases (2002)
What blood source runs along the surface of the ventral spinal cord?: The Anterior Spinal Artery
Characteristics:
Supplies approx. anterior 2/3rds of chord
Supplies the anterior horns, anterior white matter column, and lateral white matter column

Adapted from H. Blumenfeld, Neuroanatomy Through Clincal Cases (2002)
From where does the Anterior Spinal Artery arise?: The Verterbral Arteries

(Note that there is a right vertebral artery and a left vertebral artery)

Adapted from H. Blumenfeld, Neuroanatomy Through Clincal Cases (2002)
What blood source runs along the surface of the dorsal spinal cord?: Two Posterior Spinal Arteries

Characteristics:
Supplies part of the posterior horns;
Suplies the posterior columns

Adapted from H. Blumenfeld, Neuroanatomy Through Clincal Cases (2002)
From where do the Posterior Spinal Arteries arise?: The Vertebral Artery or the 'Posterior Inferior Cerebellar Artery' (PICA)

Adapted from H. Blumenfeld, Neuroanatomy Through Clincal Cases (2002)
What is the Spinal Arterial Plexus?: Plexus in this case referes to a NETWORK of blood vessels, i.e., surrounding the spinal chord & containing containing 31 segmental branches that enter the spinal canal.

Adapted from H. Blumenfeld, Neuroanatomy Through Clincal Cases (2002)

Plexus ~ "Network": from Tabors Cyclopedic Medical Dictionary, 14th Ed., 1981
What arteries form the Spinal Arterial Plexus?: The anterior and posterior spinal arteries

Adapted from H. Blumenfeld, Neuroanatomy Through Clincal Cases (2002)
Are the anterior and posterior spinal arteries of equal prominence - equidistantly spaced - at different levels of the spinal chord?: NO. They both vary in priminence at different levels.

Adapted from H. Blumenfeld, Neuroanatomy Through Clincal Cases (2002)
What are the spinal 'Radicular Arteries': Radicular means concerning a root or radicle. A radicle is a structure resemblining a rootlet. Root pertains to a porion of an organ implanted in tissues. The spinal Radicular Ateries pertain to 6 to 10 arteries (out of the 31 segmental brances in the apinal arterial plexus)arising at variable levels that reach the spinal chord.

Radicular, etc. ~ Tabors Cyclopedic Medical Dictionary, 14th Ed., 1981

Adapted from H. Blumenfeld, Neuroanatomy Through Clincal Cases (2002)
What provides major blood supply to the lumbar and sacral spinal chord?: The prominent Great Radicular Artery of Adamkiewicz

Adapted from H. Blumenfeld, Neuroanatomy Through Clincal Cases (2002)
From where does the Great Radicular Artery of Adamkiewicz arise?: Possibly anywhere between T5 and L3; USUALLY between T9 and T12

Adapted from H. Blumenfeld, Neuroanatomy Through Clincal Cases (2002)
What region of the spine is most susceptible to infarction (necrosis following cessation of blood supply) during thoracic surgery?: The Vulnerable Zone from T4 to T8 has relatively decreased perfusion. Why? It lies largely between lumbar and vertebral arterial blood supply.

Tabors Cyclopedic Medical Dictionary, 14th Ed., 1981

Adapted from H. Blumenfeld, Neuroanatomy Through Clincal Cases (2002)
Besides thoractic surgery, what else can cause infarction to the T4 to T8 Vulnerable zone?: Conditions that cause decreased aortic pressure.

Adapted from H. Blumenfeld, Neuroanatomy Through Clincal Cases (2002)
How is blood that flows into spinal chord returned?: Venous return is by a plexus (network) of veins, entitled the 'Batson's plexus': first draining into the 'Epidural Space', then intogeneral curculation
What is the significance of the epidural veins of Batson's plexus lacking valves?: Blood may reflux under conditions of increased intra-abdominal pressure. Reflux means a return or backward flow. Metastatic cells (e.g., from prostate cancer) or bacteria pelvic infections can thereby enter the epidural space around the spinal chord.

Tabors Cyclopedic Medical Dictionary, 14th Ed., 1981

Adapted from H. Blumenfeld, Neuroanatomy Through Clincal Cases (2002)

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