17 - Spinal Cord and Spinal Nerves Quiz

Questions and Answers

What are the superior and inferior boundaries of the spinal dura mater?

The superior boundary is the foramen magnum of the occipital bone, and the inferior boundary is the second sacral vertebra.

What are three spinal meninges?

Dura mater, arachnoid mater, pia mater.

What portion of the spinal cord connects with sensory and motor nerves of the upper limbs?

The cervical enlargement.

What is the difference between a horn and a column in the spinal cord?

A horn is an area of gray matter, and a column is a region of white matter. Signup and view all the answers

How many spinal cord segments are there and how are they categorized?

There are 31 pairs: cervical (8 pairs), thoracic (12 pairs), lumbar (5 pairs), sacral (5 pairs), coccygeal (1 pair). Signup and view all the answers

Why are all spinal nerves classified as mixed nerves?

Because their posterior roots contain sensory axons and their anterior roots contain motor axons. Signup and view all the answers

Which spinal nerve branches serve the upper and lower limbs?

The anterior rami. Signup and view all the answers

Which is the only spinal nerve that does not have a corresponding dermatome?

C1. Signup and view all the answers

Why does complete severing of the spinal cord at level C2 cause respiratory arrest?

It prevents descending nerve impulses from reaching the phrenic nerve, which stimulates contraction of the diaphragm. Signup and view all the answers

What five important nerves arise from the brachial plexus?

Axillary, musculocutaneous, radial, median, and ulnar nerves. Signup and view all the answers

What is the origin of the lumbar plexus?

Roots of spinal nerves L1-L4. Signup and view all the answers

What is the origin of the sacral plexus?

The anterior rami of spinal nerves L4-L5 and S1-S4. Signup and view all the answers

Based on its name, what are the position, origin, and destination of the anterior corticospinal tract?

Located on the anterior side, originates in the cortex of cerebrum, and ends in the spinal cord; it is a motor tract. Signup and view all the answers

Why is this reflex a somatic reflex?

Because the effector is a skeletal muscle. Signup and view all the answers

What is myelitis?

Inflammation of the spinal cord. Signup and view all the answers

What is meningitis?

Inflammation of the meninges due to infection. Signup and view all the answers

Where does sensory input travel?

Along the posterior columns and the spinothalamic tracts. Signup and view all the answers

Where does motor output travel?

Along direct pathways and indirect pathways. Signup and view all the answers

What are white matter tracts in the spinal cord?

They are highways for nerve impulse propagation. Signup and view all the answers

What is a reflex?

A fast, predictable sequence of involuntary actions. Signup and view all the answers

What are the three connective tissue coverings associated with spinal nerves?

Endoneurium, perineurium, epineurium. Signup and view all the answers

How are spinal nerves typically connected with the spinal cord?

By a posterior root and an anterior root. Signup and view all the answers

What are the functions of the spinal cord?

To propagate sensory impulses from receptors to the brain and motor impulses from the brain to effectors. Signup and view all the answers

Study Notes

Spinal Dura Mater Boundaries

Superior boundary: Foramen magnum of the occipital bone
Inferior boundary: Second sacral vertebra

Spinal Meninges

Dura mater: Outermost layer
Arachnoid mater: Middle layer
Pia mater: Innermost layer

Cervical Enlargement

Area of the spinal cord connecting with sensory and motor nerves of the upper limbs

Gray and White Matter

Horn: Area of gray matter in the spinal cord
Column: Region of white matter in the spinal cord

Spinal Cord Segments

Total of 31 pairs:
- Cervical: 8 pairs
- Thoracic: 12 pairs
- Lumbar: 5 pairs
- Sacral: 5 pairs
- Coccygeal: 1 pair

Mixed Nerves

All spinal nerves are classified as mixed due to the presence of both sensory axons in posterior roots and motor axons in anterior roots

Limb Innervation

Anterior rami provide motor and sensory branches to the upper and lower limbs

Dermatomes

C1 is the only spinal nerve without a corresponding dermatome

C2 Spinal Cord Injury

Complete severing at C2 leads to respiratory arrest by obstructing nerve impulses to the phrenic nerve, essential for diaphragm contraction

Brachial Plexus Nerves

Five important nerves:
- Axillary
- Musculocutaneous
- Radial
- Median
- Ulnar

Plexus Origins

Lumbar plexus: Roots of spinal nerves L1-L4
Sacral plexus: Anterior rami of spinal nerves L4-L5 and S1-S4

Anterior Corticospinal Tract

Positioned anteriorly in the spinal cord
Originates in the cerebral cortex
Descends to the spinal cord, functioning as a motor tract

Somatic Reflexes

Defined by having skeletal muscles as effectors

Myelitis

Inflammation of the spinal cord

Meningitis

Inflammation of the meninges often due to infection
Symptoms: Fever, headache, stiff neck, vomiting, confusion, lethargy, and drowsiness

Sensory Input Pathways

Travels along posterior columns and spinothalamic tracts in the white matter of the spinal cord

Motor Output Pathways

Travels via direct and indirect pathways in the white matter of the spinal cord

White Matter Tracts

Serve as highways for nerve impulse propagation
Relay sensory input to the brain and motor output from the brain to effectors

Reflex Definition

An involuntary and rapid sequence of actions in response to environmental changes
Can be spinal or cranial and somatic or autonomic

Connective Tissue Coverings of Spinal Nerves

Endoneurium: Covers individual axons
Perineurium: Surrounds groups of axons
Epineurium: Encloses the entire nerve

Connection to Spinal Cord

Spinal nerves typically connect via a posterior root (sensory) and anterior root (motor)

Functions of the Spinal Cord

White matter: Propagates sensory impulses to the brain and motor impulses to effectors
Gray matter: Integrates sensory input and motor output

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Description

Test your knowledge on the spinal cord and spinal nerves with this quiz. Explore the boundaries of the spinal dura mater, the three layers of the meninges, and more. Perfect for students studying neuroanatomy.