Spinal Anatomy and Function Quiz
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Questions and Answers

What function do the spinal tracts primarily serve?

  • They bundle axons for sensory and motor information. (correct)
  • They transport neurotransmitters between neurons.
  • They regulate blood flow within the spinal cord.
  • They provide structural support to the spinal cord.

Which spinal tract is responsible for pain and temperature sensation?

  • Posterior funiculi
  • Spinocerebellar tracts
  • Spinothalamic tracts (correct)
  • Direct pathways (pyramidal tracts)

What characterizes the direct pathways (pyramidal tracts)?

  • They manage the unconscious proprioception.
  • They facilitate pain and temperature sensations.
  • They handle automatic movements.
  • They control precise, voluntary movements. (correct)

What is the primary role of the spinal ganglia?

<p>They house sensory neuron cell bodies. (A)</p> Signup and view all the answers

Which of the following describes the function of indirect pathways (extrapyramidal tracts)?

<p>They coordinate automatic and gross movements. (C)</p> Signup and view all the answers

What is the primary function of the cervical plexus?

<p>Innervates the skin and muscles of the head and neck (D)</p> Signup and view all the answers

Which spinal nerves contribute to the brachial plexus?

<p>C5 to T1 (D)</p> Signup and view all the answers

What body areas does the lumbar plexus innervate?

<p>Abdominal wall and anterior-medial thigh (A)</p> Signup and view all the answers

Which nerve is associated with the cervical plexus that plays a critical role in diaphragm innervation?

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

The sacral plexus primarily innervates which part of the body?

<p>Buttocks and part of the lower limb (A)</p> Signup and view all the answers

What is the primary function of the spinal cord?

<p>To conduct impulses from the body to the brain and vice versa (A)</p> Signup and view all the answers

Which part of the spinal cord is known as the cone-shaped end?

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

Which is NOT a component of the gray matter in the spinal cord?

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

Which structure stabilizes the spinal cord within the spinal canal?

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

What shape is the gray matter in the spinal cord typically described as?

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

Which spinal region contains the lateral horn, which houses autonomic motor cell bodies?

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

What is the length range of the spinal cord in centimeters?

<p>42-45 cm (D)</p> Signup and view all the answers

Which part of the spinal cord contains both sensory and motor nerve tracts?

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

What is the primary function of the stretch reflex?

<p>To prevent over-stretching injury (A)</p> Signup and view all the answers

Which type of reflex is the flexor (withdrawal) reflex classified as?

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

What role do tendon organs play in the tendon reflex?

<p>Prevent over-contraction of muscles (B)</p> Signup and view all the answers

Which structure serves as the outermost covering of a spinal nerve?

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

How many total pairs of spinal nerves are present in the human body?

<p>31 (C)</p> Signup and view all the answers

What is the function of the anterior ramus of spinal nerves?

<p>Supplies limbs and anterior body (B)</p> Signup and view all the answers

Which part of the reflex arc is responsible for carrying signals from the sensory receptors to the spinal cord?

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

What is one of the physiological roles of reflexes in the body?

<p>Maintain posture and balance (B)</p> Signup and view all the answers

Flashcards

Spinal Tracts

Bundles of axons in the spinal cord, carrying sensory and motor information in different directions (ascending for sensory, descending for motor).

Spinal Ganglia (Dorsal Root Ganglia)

Cell bodies of sensory neurons located in clusters along the dorsal root of the spinal cord.

Spinothalamic Tracts

The ascending tracts in the spinal cord that carry information about pain, temperature, deep pressure, and crude touch.

Direct Pathways (Pyramidal Tracts)

The descending tracts in the spinal cord that control precise, voluntary movements, often referred to as 'skilled movements.'

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Indirect Pathways (Extrapyramidal Tracts)

The descending tracts in the spinal cord responsible for coordinating automatic movements, muscle tone, and posture.

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What is the spinal cord?

A flattened cylinder, about 42-45 cm long and 2 cm in diameter, located within the spinal canal.

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What are the enlargements of the spinal cord?

Consists of two enlargements in the cervical and lumbosacral regions, where nerves to the limbs originate.

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What is the conus medullaris?

The cone-shaped end of the spinal cord.

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What is the cauda equina?

A bundle of nerve roots extending from the conus medullaris.

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What is the filum terminale?

A thin, thread-like extension of the pia mater that anchors the spinal cord within the spinal canal.

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What is the gray matter of the spinal cord?

H-shaped central region of the spinal cord, containing cell bodies of neurons and interneurons.

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What is the white matter of the spinal cord?

The outer region of the spinal cord, composed of myelinated axons, carrying sensory and motor information.

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What are spinal tracts?

Bundles of nerve fibers within the white matter that transmit specific types of information.

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Plexus

A network of nerves formed by the joining of anterior rami of spinal nerves. It acts as a 'junction box' for distributing nerve signals to specific body regions.

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Cervical Plexus

A nerve plexus located in the neck, formed by the anterior rami of spinal nerves C1-C4. It innervates the skin and muscles of the head, neck, and superior shoulders, including the diaphragm.

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Brachial Plexus

A nerve plexus situated in the shoulder and upper limb, originating from the anterior rami of spinal nerves C5-T1. It controls the muscles and sensations of the arm, hand, and shoulder.

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Lumbar Plexus

A nerve plexus found in the lower back, formed by the anterior rami of spinal nerves L1-L4. It controls the muscles and sensations of the abdominal wall, external genitals, and anterior-medial thigh.

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Sacral Plexus

A nerve plexus located in the pelvis, formed by the anterior rami of spinal nerves L4-S4. It innervates the buttocks, perineum, and part of the lower limb.

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Reflex Arc

A reflex pathway that bypasses the brain, allowing for quick and automatic responses to stimuli. It involves a sensory receptor, an afferent neuron, an efferent neuron, and an effector.

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Stretch Reflex

A type of reflex that helps prevent overstretching of a muscle by triggering a contraction in the same muscle. This is often tested by tapping on the patellar tendon below the knee.

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Tendon Reflex

A reflex that occurs when a tendon is stretched too far. It causes the muscle attached to the tendon to relax, preventing damage to the tendon.

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Flexor (Withdrawal) Reflex

A reflex that involves multiple synapses and several spinal cord segments. It's triggered by pain and causes withdrawal of the affected limb.

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Spinal Nerves

These are nerves that branch from the spinal cord and exit through openings between the vertebrae. They carry both sensory and motor information, making them 'mixed nerves'.

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Spinal Nerve Coverings

A protective covering around spinal nerves. It's composed of three layers: epineurium, perineurium, and endoneurium.

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Posterior Root

The roots (bundles of nerve fibers) that carry sensory information into the spinal cord. These roots are located on the dorsal side of the spinal cord.

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Anterior Root

The roots (bundles of nerve fibers) that carry motor information from the spinal cord to the muscles. These roots are located on the ventral side of the spinal cord.

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Study Notes

Spinal Cord and Spinal Nerves

  • The spinal cord conducts sensory impulses from the body to the brain and motor impulses from the brain to the body. It also controls reflex activities.
  • The spinal cord is a flattened cylinder, approximately 42-45 cm long and 2 cm in diameter. It lies within the spinal canal.
  • The spinal cord has enlargements: cervical (upper limbs) and lumbosacral (lower limbs). It also has a cone-shaped end (conus medullaris), a collection of nerve roots (cauda equina), and a thread-like extension (filum terminale).

Spinal Cord Structure

  • The spinal cord has gray and white matter.
  • Gray matter is shaped like a butterfly (or letter H) and is divided into horns.
  • Gray matter contains sensory axons, interneurons, cell bodies of lower motor neurons (LMN), and, in the thoracic region, autonomic motor cell bodies.
  • White matter surrounds gray matter and is divided into funiculi (columns). White matter contains sensory and motor nerve tracts.

Spinal Nerves

  • Spinal nerves emerge from the spinal cord as roots.
  • Posterior roots contain sensory fibers.
  • Anterior roots contain motor fibers.
  • Spinal ganglia (dorsal root ganglia) contain the cell bodies of sensory neurons.

Spinal Tracts

  • Spinal tracts are bundles of axons that act as highways for sensory and motor information.
  • Sensory tracts ascend, and motor tracts descend.
  • Spinal tracts form the white matter of the spinal cord.
  • Important examples of spinal tracts include:
    • Direct (pyramidal): precise, voluntary movements
    • Indirect (extrapyramidal): automatic movements; coordinates gross movements and visual reflexes
    • Posterior funiculi: proprioception, discriminative touch, two-point discrimination, pressure, vibration
    • Spinothalamic: pain, temperature, deep pressure, crude touch
    • Spinocerebellar: unconscious proprioception

Spinal Reflexes

  • Reflexes are fast, predictable, automatic responses to environmental changes.
  • Examples of spinal reflexes include:
    • Stretch reflex (e.g., patellar reflex): monosynaptic, prevents overstretching injury
    • Tendon reflex: activates when tendon stretches, muscle relaxes, and antagonistic muscle contracts; protects tendons from damage
    • Flexor (withdrawal) reflex: polysynaptic; multiple muscle groups activate to lift a limb from a painful stimulus.

Physiological Role of Reflexes

  • Reflexes promote homeostasis by minimizing exposure to noxious stimuli, maintaining posture and balance, and coordinating movements.

Spinal Nerves (Peripheral)

  • Spinal nerves branch from the spinal cord and emerge through intervertebral foramina.
  • Spinal nerves are mixed nerves (containing both sensory and motor fibers).
  • Spinal nerves have coverings including epineurium (outer layer), perineurium (covering fascicles), and endoneurium (covering individual axons/nerve fibers).

Spinal Nerve Plexuses

  • Plexuses are complex networks of nerves, serving as "junction boxes" for anterior rami of spinal nerves.
  • They are found in cervical, brachial, lumbar, and sacral regions.
  • Each plexus innervates specific body regions:
    • Cervical plexus: innervates the skin and muscles of the head, neck, and shoulders (e.g., phrenic nerve to the diaphragm); C1-C5
    • Brachial plexus: innervates the shoulder and upper limb; C5-T1
    • Lumbar plexus: innervates the abdominal wall, external genitals, and anterior-medial thigh; L1-L4
    • Sacral plexus: innervates the buttocks, perineum, and lower limb; L4-S4

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Description

Test your knowledge on the anatomy and functions of the spinal tracts, ganglia, and plexuses. This quiz covers topics such as pain and temperature sensation, direct and indirect pathways, and specific nerves involved in innervation. Perfect for students studying human anatomy and physiology.

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