Gross Anatomy of the Spinal Cord
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Questions and Answers

What is one of the late signs of spinal cord dysfunction?

  • Lax rectal sphincter tone (correct)
  • Hyperactive Babinski reflex
  • Enhanced muscle strength
  • Increased reflex activity

Which tracts are most vulnerable to mechanical pressure in spinal cord dysfunction?

  • Ventral and dorsal root fibers
  • Corticospinal and spinocerebellar tracts (correct)
  • Visual and auditory tracts
  • Anterior and lateral spinothalamic tracts

What percentage of patients may be paraplegic at the time of diagnosis for spinal cord compression due to a tumor?

  • 15% (correct)
  • 5%
  • 25%
  • 10%

What type of sensations are evaluated by the sensory system during muscle testing?

<p>Pain, temperature, position, and vibration (B)</p> Signup and view all the answers

How do normally innervated muscles respond to faradic current?

<p>The contraction continues only while the current is present. (B)</p> Signup and view all the answers

How can neoplasms affect the spinal cord beyond physical compression?

<p>They may compromise the vascular supply (D)</p> Signup and view all the answers

What is a common symptom associated with pathologic vertebral fractures?

<p>Babinski reflexes (C)</p> Signup and view all the answers

What happens to a muscle when the lower motor neuron is cut?

<p>It stops responding to both types of electrical stimulation after 7 days. (C)</p> Signup and view all the answers

What type of current causes contraction only when it is turned on or off?

<p>Direct current (C)</p> Signup and view all the answers

After how many days does the response to direct current cease following the section of the nerve?

<p>10 days (C)</p> Signup and view all the answers

What involves the cortex in terms of sensory evaluation?

<p>Discriminative sensations (D)</p> Signup and view all the answers

Which pathways are responsible for transmitting pain and temperature sensations?

<p>Spinothalamic tracts and posterior columns (D)</p> Signup and view all the answers

What is the primary sensation not reliant on the cortex according to the content?

<p>Vibration (D)</p> Signup and view all the answers

What anatomical structures comprise a reflex arc in its simplest form?

<p>A receptor organ, an afferent neuron, and an effector organ (A)</p> Signup and view all the answers

Which reflex is referred to as a monosynaptic reflex arc?

<p>The brachioradialis reflex (C)</p> Signup and view all the answers

How are reflexes graded according to their response?

<p>0 is no response, 3+ is hyperactive (D)</p> Signup and view all the answers

What characterizes lesions of the corticospinal tracts in relation to reflexes?

<p>Presence of the Babinski sign and absence of superficial abdominal reflexes (A)</p> Signup and view all the answers

What is the result of lesions in the descending tracts other than the corticospinal tract?

<p>Spasticity with exaggerated deep muscle reflexes (B)</p> Signup and view all the answers

Which of the following statements about the assessment of the motor system is true?

<p>Evaluate the clasp-knife reaction (A)</p> Signup and view all the answers

What tool should be properly selected for assessing reflexes?

<p>A properly weighed reflex hammer (D)</p> Signup and view all the answers

What indicates a brisker than average reflex response on the grading scale?

<p>3+ response possibly indicative of disease (A)</p> Signup and view all the answers

Which reflex is least likely to be affected by lesions in the corticospinal tract?

<p>The patellar reflex (C)</p> Signup and view all the answers

Which option describes the role of reflex arcs in the spinal cord?

<p>Reflex arcs maintain body posture (D)</p> Signup and view all the answers

Which reflex assessment indicates a lack of control at the distal ends of limbs?

<p>Presence of clonus in the flexors (B)</p> Signup and view all the answers

When is the flat end of a reflex hammer most appropriately used?

<p>When less discomfort is preferred at large muscle groups (A)</p> Signup and view all the answers

What is indicated by a score of 4+ on the reflex grading scale?

<p>Very brisk reflex activity with clonus (A)</p> Signup and view all the answers

What happens during a clasp-knife reaction?

<p>Sudden relaxation of muscle tension (D)</p> Signup and view all the answers

Which of the following is a common sign in upper motor neuron lesions?

<p>Presence of the Babinski sign (B)</p> Signup and view all the answers

What is the termination point of the spinal cord in adults?

<p>At the level of the first lumbar vertebra (C)</p> Signup and view all the answers

Which region of the spinal cord contains the largest amount of gray matter?

<p>Cervical region (A)</p> Signup and view all the answers

What type of neurons are associated with the anterior gray column?

<p>Alpha efferents (B)</p> Signup and view all the answers

Which description best fits the substantia gelatinosa?

<p>Receives afferent fibers related to pain and temperature. (D)</p> Signup and view all the answers

Which area of the spinal cord contains the nucleus dorsalis?

<p>Extends from C8 to L3 or L4 (A)</p> Signup and view all the answers

What is the function of the lateral gray column?

<p>Contains neurons for sympathetic and parasympathetic fibers. (A)</p> Signup and view all the answers

In which type of white matter tract does proprioceptive information ascend?

<p>Dorsal column-medial lemniscal pathway (D)</p> Signup and view all the answers

What is primarily conveyed in the anterior spinothalamic tract?

<p>Crude touch and pressure (D)</p> Signup and view all the answers

What characterizes the posterior funiculus of the spinal cord?

<p>Composed almost exclusively of ascending fibers (C)</p> Signup and view all the answers

Which group of nerve cells is believed to receive visceral afferent information?

<p>Visceral afferent nucleus (C)</p> Signup and view all the answers

Which of the following is true about cerebrospinal fluid in relation to the spinal cord?

<p>It surrounds the spinal cord in the subarachnoid space. (B)</p> Signup and view all the answers

What can be said about the anterior median fissure of the spinal cord?

<p>It extends along the length of the spinal cord. (A)</p> Signup and view all the answers

What role do gamma efferents play in the spinal cord?

<p>Innervate intrafusal muscle fibers of neuromuscular spindles (D)</p> Signup and view all the answers

The thoracic and upper lumbar segments of the spinal cord are characterized by which unique feature?

<p>Presence of distinct lateral gray columns or horns (D)</p> Signup and view all the answers

What indicates the existence of spinal shock in a patient with suspected spinal cord compression?

<p>Absent anal reflex (B)</p> Signup and view all the answers

Which age group is most likely to experience the peak incidence of primary spinal cord tumors?

<p>People aged 30-50 years (B)</p> Signup and view all the answers

In which region are metastatic spinal lesions most commonly observed?

<p>Thoracic spine (D)</p> Signup and view all the answers

What is typically the first symptom of spinal cord compression due to neoplastic disease?

<p>Gradually worsening back pain (B)</p> Signup and view all the answers

Which of the following cancers is most likely to contribute to spinal cord metastasis?

<p>Melanoma (B)</p> Signup and view all the answers

Which symptom typically emerges early in conus medullaris syndrome?

<p>Saddle anesthesia (A)</p> Signup and view all the answers

What is a likely consequence of spinal cord compression that occurs without early detection and intervention?

<p>Rapid progression of symptoms (A)</p> Signup and view all the answers

Which statement best defines the nature of primary spinal cord tumors?

<p>They arise from different elements of the central nervous system. (D)</p> Signup and view all the answers

In advanced stages of spinal cord compression, what occurs?

<p>Complete motor paralysis (C)</p> Signup and view all the answers

Which factors are effective in predicting ultimate disability in patients with spinal cord compression?

<p>Initial disability at the time of therapy initiation (C)</p> Signup and view all the answers

What is a common complaint in adults with spinal cord neoplasms?

<p>Pain (B)</p> Signup and view all the answers

What is the most frequent consequence of metastatic lesions affecting the spinal region?

<p>Spinal cord compression (C)</p> Signup and view all the answers

Which statement is true regarding intramedullary tumors?

<p>Their symptoms mimic those of epidural compression. (B)</p> Signup and view all the answers

What clinical sign indicates meningeal irritation, often associated with spinal cord neoplasms?

<p>Lhermitte sign (B)</p> Signup and view all the answers

What type of spinal cord disorder arises from lateral spinal cord compression?

<p>Brown-Séquard syndrome (C)</p> Signup and view all the answers

What imaging modality provides the best definition of spinal lesions?

<p>MRI (A)</p> Signup and view all the answers

What is a typical consequence of tumors located in the region of the foramen magnum?

<p>Quadriparesis (C)</p> Signup and view all the answers

What factor is crucial in managing spinal cord compression secondary to cancer?

<p>Rapid diagnosis and treatment (B)</p> Signup and view all the answers

Which symptom may occur in about 10% of patients with leptomeningeal metastasis?

<p>Nuchal rigidity (A)</p> Signup and view all the answers

What may an isolated sensory loss in the upper extremities indicate?

<p>Cervical intramedullary tumor (C)</p> Signup and view all the answers

What is the role of steroids in the management of cord compression due to neoplasms?

<p>To manage inflammatory response (B)</p> Signup and view all the answers

Which treatment approach should be pursued after appropriate imaging for an epidural tumor compression?

<p>Radiation therapy (C)</p> Signup and view all the answers

What condition can result from the presence of multiple spinal metastases?

<p>Spinal cord dysfunction (B)</p> Signup and view all the answers

Which surgical procedure provides immediate relief of spinal cord compression?

<p>Surgical decompression (A)</p> Signup and view all the answers

What does an MRI help differentiate between in spinal conditions?

<p>Osteoporosis and malignant disease (A)</p> Signup and view all the answers

In which patient scenario should chemotherapy be administered at the discretion of the consultant?

<p>For patients with spinal cord compression (B)</p> Signup and view all the answers

Flashcards

Sensory System Evaluation

Assessing the function of various senses, including pain, temperature, position, vibration, light touch, and discriminative sensations.

Spinothalamic Tracts

Neural pathways transmitting pain and temperature sensations.

Posterior Columns

Neural pathways transmitting position and vibration sensations.

Faradic Current

Interrupted electrical stimulation that causes muscle contraction

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Direct Current

Continuous electrical stimulation, resulting in muscle contraction only when the current is turned on/off.

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Lower Motor Neuron Damage

Damage to the lower motor neuron, leading to muscle response loss to interrupted electrical stimulation.

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Response to Direct Current (after 10 days)

Loss of muscle response to direct current stimulation 10 days after lower motor neuron damage.

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Paralyzed Muscle Evaluation

Evaluation of the sensory system, particularly the muscles which are paralysed

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Reflex Arc

A nerve pathway that controls a reflex action, consisting of a receptor, afferent neuron, spinal cord, effector neuron, and effector organ.

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Monosynaptic Reflex Arc

A reflex arc involving only one synapse between the sensory and motor neurons.

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Muscle Tone

The state of slight tension in muscles, maintaining posture and readiness for movement.

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Reflex Hammer

Tool used to elicit reflexes by striking a tendon.

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Reflex Grading Scale

A scale (0-4+) used to describe the strength of a reflex response.

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0 Reflex

No response to the reflex stimulus.

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4+ Reflex

A very brisk, hyperactive reflex with clonus (rhythmic oscillations).

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Babinski Sign

Abnormal reflex response in which the big toe extends upward instead of downward.

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Upper Motor Neuron Lesion

Damage to the motor pathways in the brain and spinal cord.

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Deep Muscle Reflexes

Reflexes elicited by tapping tendons connected to muscles.

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Spasticity/Hypertonicity

Increased muscle stiffness or tension.

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Clasp-Knife Reaction

A characteristic resistance to motion that suddenly releases, like a closing clasp-knife.

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Superficial Abdominal Reflexes

Reflexes elicited by stroking the skin over the abdominal muscles.

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Cremasteric Reflex

Reflex that affects the cremaster muscle (raises the testicle).

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Corticospinal Tract

Major pathway for motor signals from the brain to the body

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Spinal Cord Shape

The spinal cord is roughly cylindrical.

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Spinal Cord Location

The spinal cord occupies the upper two-thirds of the vertebral canal, protected by meninges and cerebrospinal fluid.

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Spinal Cord Origin

The spinal cord begins at the foramen magnum and continues inferiorly in the vertebral canal.

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Gray Matter Shape

The gray matter is shaped like an H on cross-section, with anterior and posterior horns.

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Gray Matter Horns

Anterior and posterior horns of the H-shaped gray matter, connected by a gray commissure.

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Lateral Gray Column

A smaller gray column present in thoracic and upper lumbar segments, related to muscle innervation.

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Cervical & Lumbar Enlargements

Fusiform enlargements in the cervical and lumbar regions, maximizing control of limbs.

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Spinal Nerves

31 pairs attached to the spinal cord via anterior and posterior roots.

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Posterior Root Ganglion

Part of the posterior root containing nerve cells, with peripheral & central fibers.

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Substantia Gelatinosa

Important nucleus in the posterior gray column associated with pain, temp & touch sensations.

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Nucleus Proprius

Large nerve cells in the posterior gray column, associated with proprioception.

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Clark's Column

Nucleus dorsalis (Clark's column), nerve cells related to proprioception, located in the posterior gray column (C8-L3).

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Visceral Afferent Nucleus

Medium-sized nerve cells in the lateral posterior gray, associated with visceral afferent information (T1-L3).

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Intermediolateral Group

Lateral gray column, gives rise to preganglionic sympathetic fibers (T1-L2/3).

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Gray Commissure

Connects anterior & posterior gray columns, houses the central canal.

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White Matter Columns

Anterior, posterior, and lateral - carry ascending/descending tracts.

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Spinal Cord Compression Symptoms

Symptoms appear when a spinal fracture, or epidural extension, is present. Late sign is lax rectal sphincter tone.

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Vulnerable Nerve Tracts

Nerve tracts easily affected by mechanical pressure include the corticospinal, spinocerebellar tracts, and the posterior spinal columns.

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Tumor & Compression

Almost half of patients with tumors and subsequent spinal cord compression experience some degree of paralysis; 15% are paraplegic at diagnosis.

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Neoplasms & Vascular Supply

Tumors can disrupt the blood supply to the spinal cord, causing swelling or reduced blood flow (ischemia).

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Babinski Reflex

A presence of the Babinski reflex may suggest damage to nerve tracts, potentially indicative of spinal cord injury or tumors.

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Spinal Shock

A temporary loss of function below the site of spinal cord injury, characterized by absence of reflexes.

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Anal Reflex

Reflex response of the anal sphincter to stimulation; used to assess spinal cord function.

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Spinal Cord Compression

Pressure on the spinal cord, often leading to sensory and motor deficits. Often a sign of metastasis

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Metastatic Spinal Cord Compression

Spinal cord compression resulting from cancer spreading to the spine.

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Primary Spinal Cord Tumor

A tumor originating directly from tissues within the spinal cord.

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Intramedullary vs. Extramedullary

Intramedullary tumors arise inside the spinal cord; extramedullary tumors arise outside the spinal cord.

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Incidence Peak Age

Primary spinal cord tumors commonly occur in individuals between 30-50 years old.

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Metastatic Spread

The way cancer spreads via the bloodstream to other parts of the body.

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Most Frequent Metastasis Location

Thoracic spine is the most affected, followed by the lumbar spine.

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Pain Prediction

Pain is often the first symptom, especially in adults with spinal cord tumors, preceding other symptoms by several months

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Pain Characterization

Pain in spinal cord tumors can be radicular (near nerves) or localized to the back, and may be exacerbated by movement.

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Bowel/Bladder Dysfunction

Problems with bowel and bladder control can be a late sign of spinal cord compression, but may be early with conus medullaris syndrome

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Clinical Presentation Similarity

Clinical symptoms of metastatic and primary spine cancers often overlap, making diagnosis challenging

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Early Neurological Deficits

Early signs include paresthesias/weakness in limbs/sensory loss like pain/temperature sensation loss.,

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Diagnosis Importance

Early detection of cord compression and intervention are key to mitigating long term effects

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Spinal Cord Neoplasms

Tumors affecting the spinal cord, causing non-specific symptoms initially.

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Lhermitte Sign

Sudden, electric shock-like pain with neck flexion, indicating meningeal irritation.

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Nuchal Rigidity

Stiffness of the neck.

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Brown-Séquard Syndrome

Partial cord disorder causing contralateral motor and sensory deficits from lateral spinal cord compression.

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Cauda Equina Lesions

Damage to the end of the spinal cord and nerve roots, causing upper and lower motor neuron signs.

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Foramen Magnum Tumors

Tumors in the foramen magnum (base of skull) causing quadriparesis and widespread weakness.

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Cervical Intramedullary Tumors

Tumors within the cervical spinal cord causing isolated sensory loss in the upper limbs.

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Syrinx

Cavity within the spinal cord causing unusual clinical pictures.

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MRI

Magnetic Resonance Imaging used to visualize the spinal cord and surrounding area.

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Spinal Epidural Metastases

Spinal tumors that metastasize into many areas (multi-spinal).

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Vertebral Collapse

Compression of spinal vertebrae.

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Emergency Department Care (Spinal Cord)

Rapid diagnosis and treatment for spinal cord emergencies due to tumors, preventing permanent damage.

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Steroid Administration

Administering steroids to potentially reduce spinal cord swelling.

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Radiation Therapy

Radiation approach for tumor compression, using imaging consultations.

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Surgical Decompression

Surgery to remove pressure on the spinal cord, providing immediate relief.

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Study Notes

Gross Anatomy of the Spinal Cord

  • Cylindrical shape, extending from foramen magnum to L1 vertebra.
  • Surrounded by meninges (dura, arachnoid, pia).
  • Cerebrospinal fluid in subarachnoid space.
  • Cervical and lumbar enlargements for innervation of limbs.
  • Conus medullaris is the tapered inferior end.
  • Filum terminale extends from conus and anchors the cord.
  • Anterior median fissure and posterior median sulcus mark the midline.
  • 31 pairs of spinal nerves attach, anterior (motor) and posterior (sensory) roots.
  • Each root connects to the cord by rootlets.
  • Posterior root ganglion houses sensory neuron cell bodies.

Anatomy of the Gray Matter

  • Central H-shaped core of gray matter is surrounded by white matter.
  • Anterior and posterior gray horns are joined by a thin gray commissure.
  • A lateral gray horn exists in thoracic and upper lumbar segments.
  • Gray matter size is related to muscle innervation, largest in cervical and lumbosacral enlargements.

Nerve Cell Groups in the Anterior Gray Column

  • Primarily large, multipolar neurons whose axons form alpha efferent fibers to skeletal muscles.
  • Smaller neurons form gamma efferent fibers to intrafusal muscle fibers of neuromuscular spindles.

Nerve Cell Groups in the Posterior Gray Column

  • Four groups of nerve cells, some extending the full length of the cord, others to thoracic/lumbar.
  • Substantia gelatinosa: receives pain, temperature, and touch signals from posterior root.
  • Nucleus proprius: receives proprioceptive, two-point discrimination and vibration signals from posterior white column.
  • Nucleus dorsalis (Clark's column): receives proprioceptive input (neuromuscular & tendon spindles) from C8-L3/L4.
  • Visceral afferent nucleus: receives visceral afferent information (medium-sized cells) from T1-L3.

Anatomy of the White Matter

  • Composed of anterior, lateral, and posterior white columns.
  • Contains ascending and descending tracts and intersegmental tracts.
  • Ascending tracts carry sensory information, descending carry motor.

Ascending Tracts and Their Functions

  • Lateral spinothalamic tract: pain and temperature.
  • Anterior spinothalamic tract: light touch and pressure.
  • Posterior white columns: discriminative touch, vibration, and conscious muscle joint sense.
  • Spinocerebellar tracts (anterior and posterior): unconscious proprioceptive and sensory information to cerebellum.
  • Spinotectal tract: relays pain, thermal, and tactile info to superior colliculus (spinovisual reflexes).
  • Spino-olivary tract: info to the cerebellum.

Descending Tracts and Their Functions

  • Corticospinal tract: voluntary, skilled movements (especially distal limbs).
  • Reticulospinal tract: facilitates or inhibits alpha and gamma motor neuron activity.
  • Tectospinal tract: reflex postural movements in response to visual stimuli.
  • Rubrospinal tract: facilitates flexor muscles, inhibits extensor muscles.
  • Vestibulospinal tract: facilitates extensors, inhibits flexors, related to balance.
  • Autonomic descending fibers control visceral activity.

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Description

Explore the key features of spinal cord anatomy, including its structure, surrounding meninges, and the arrangement of gray and white matter. This quiz covers essential concepts such as spinal nerve pairs, the significance of cervical and lumbar enlargements, and the organization of nerve cell groups.

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