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Questions and Answers
What primarily composes the white matter of the spinal cord?
Which commissure of the spinal cord is located in front of the central canal?
Which structure is NOT a part of the gray matter in the spinal cord?
The lateral horn of the gray matter is present only in which segments of the spinal cord?
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What does the central group of gray matter in the spinal cord primarily supply?
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What is the primary role of the medial group of the spinal cord's gray matter?
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What type of sensory information does the postromarginal nucleus primarily process?
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Which part of the spinal cord's gray matter is responsible for facilitating crude touch and light pressure sensations?
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Which spinal cord column is composed of axons transmitting sensory information toward the brain?
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Which type of muscle activity is primarily controlled by the ventral horn of the spinal cord?
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What is the primary function of the anterior spinal artery?
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Which arteries primarily supply blood to the lower 2/3 of the spinal cord?
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How many posterior spinal arteries are there?
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From which arteries do the radicular arteries originate in the neck?
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What is the origin of the anterior spinal artery?
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Where do the posterior spinal arteries pass in relation to the spinal cord?
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What do group of veins correspond to the arterial supply of the spinal cord?
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Which artery is sometimes associated with the origin of the posterior spinal arteries?
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Study Notes
Blood Supply of the Spinal Cord
- The spinal cord is supplied by three main arteries:
- Anterior spinal artery
- Two posterior spinal arteries
- Segmental spinal arteries (radicular arteries)
-
Anterior Spinal Artery:
- Single artery that arises from the union of the two anterior spinal branches of the vertebral arteries.
- Runs along the anterior median fissure, supplying the anterior two-thirds of the spinal cord.
-
Posterior Spinal Arteries:
- Two arteries branching from the vertebral artery (sometimes arising from the posterior inferior cerebellar artery - PICA).
- Runs in the posterolateral sulcus of the spinal cord, supplying the posterior one-third of the spinal cord.
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Radicular Arteries:
- Radicular arteries are branches of major arteries that enter the vertebral canal through the intervertebral foramina.
- Major source of blood supply for the lower two-thirds of the spinal cord.
- They join the anterior and posterior spinal arteries.
- Radicular arteries originate from:
- Neck: vertebral and ascending cervical arteries.
- Thorax: intercostal arteries.
- Abdomen: lumbar arteries.
- Pelvis: lateral sacral arteries.
Venous Drainage of the Spinal Cord
- The six longitudinal channels correspond to the arteries:
- Anterior spinal veins
- Posterior spinal veins
- Anterolateral spinal veins (two)
- Posterolateral spinal veins (two)
- These veins drain into the internal vertebral plexus of veins.
Internal Structure of the Spinal Cord
-
Gray Matter:
- Composed primarily of neuron cell bodies.
- H-shaped or butterfly-like.
- Gray commissure: contains the central canal.
- Anterior horns: contain cell bodies of motor neurons.
- Posterior (dorsal) horns: consists of interneurons (contain sensory nuclei).
- Lateral horn: present only in thoracic and lumbar segments (T1-L2) for sympathetic nuclei, and sacral segments (S2, 3, 4) for parasympathetic nuclei.
-
White Matter:
- Composed of nerve fibers (ascending and descending tracts) with myelin sheaths.
Commissures of the Spinal Cord
- The two halves of the spinal cord are connected by three commissures:
- White commissure
- Anterior gray commissure (infront of the central canal)
- Posterior gray commissure (behind the central canal)
Gray Matter of the Spinal Cord & Spinal Roots
-
Motor Neurons:
- Ventral Horn: - Medial group: for trunk muscles (L1 to S3). - Lateral group: supply the limb muscles (L1 to S3). - Central group: in cervical region only (phrenic nerve and spinal accessory nerve).
-
Dorsal horn (sensory) afferent:
- Substantia Gelatinosa of Rolandi (SGR): pain, temperature, and touch.
- Nucleus proprius: crude touch, light pressure (all levels).
- Postromarginal nucleus: pain and temperature (all levels).
- Clarke’s Nucleus: proprioception (C8-L2).
-
Lateral horn:
- Present only in thoracic and lumbar segments (T1-L2) for sympathetic nuclei, and sacral segments (S2, 3, 4) for parasympathetic nuclei.
White Matter of the Spinal Cord
- Composed of axons of nerve cells, forming tracts or fasciculi.
- Three types of fibers:
- Ascending (ventral) columns
- Descending (dorsal) columns
- Lateral columns
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Description
Explore the intricate blood supply system of the spinal cord, including the roles of the anterior spinal artery, posterior spinal arteries, and segmental spinal arteries. This quiz examines the pathways and functions of these key arteries essential for spinal cord health and function.
