Chapter 14 (ALL) Flashcards
Which of the following statements about cranial nerves is not true:
-There are 12 pairs of cranial nerves.
-The cranial nerves only innervate the head and neck.
-Most cranial nerves are mixed sensory and motor, though two are purely sensory.
-The vagus nerve is the only cranial nerve that travels to the thoracic and abdominal cavities.
-All are true statements.
The cranial nerves only innervate the head and neck.
Explanation: The vagus nerve (cranial nerve X) innervates structures in the thorax and abdomen, thus not all cranial nerves only innervate the head and neck.
Innervation of skeletal muscle takes place at:
-Diffusion junctions
-Ganglia
-The neuromuscular junction
-Synapses en passant
The neuromuscular junction.
Explanation: Skeletal muscle is innervated at the neuromuscular junction, where motor neurons communicate with muscle fibers to initiate contraction.
Most ventral rami branch and rejoin one another lateral to the vertebral column to form structures called:
-Plexuses
-Rami
-Ganglia
-Anastomoses
Plexuses.
Explanation: The ventral rami of spinal nerves form networks called plexuses (e.g., brachial plexus, lumbar plexus) which distribute nerve fibers to various body regions.
Reflexes are nearly instantaneous responses of the nervous system that do not require a stimulus.
True
False
False.
Explanation: Reflexes are responses to stimuli; they require a stimulus to be initiated.
Mechanoreceptors of the peripheral nervous system respond to touch, pressure, vibration and stretch.
True
False
True.
Explanation: Mechanoreceptors detect mechanical changes such as touch, pressure, vibration, and stretch.
Reflex arcs are found only in the autonomic nervous system.
True
False
False.
Explanation: Reflex arcs are found in both the autonomic and somatic nervous systems.
The vagus nerve is the only cranial nerve that travels to the thoracic and abdominal cavities.
True
False
True.
Explanation: The vagus nerve (cranial nerve X) is the only cranial nerve that extends beyond the head and neck to the thorax and abdomen.
Nerves found in the PNS usually carry both sensory and motor fibers.
True
False
True.
Explanation: Most peripheral nerves are mixed nerves, carrying both sensory and motor fibers.
The ventral roots of the spinal cord contain sensory fibers from sensory neuron cell bodies located in the dorsal root ganglia.
True
False
False.
Explanation: The ventral roots contain motor fibers, whereas the dorsal roots contain sensory fibers from neurons in the dorsal root ganglia.
Most spinal and cranial nerves contain both somatic and autonomic fibers.
True
False
True.
Explanation: Most spinal and cranial nerves have both somatic (voluntary) and autonomic (involuntary) fibers, allowing them to control both voluntary muscles and involuntary functions.
The 31 pairs of spinal nerves innervate all parts of the body other than the head and part of the neck.
True
False
True.
Explanation: The 31 pairs of spinal nerves extend to all parts of the body except the head and part of the neck, which are primarily innervated by cranial nerves.
Reflexes always involve the brain.
True
False
False.
Explanation: Reflexes can be mediated through the spinal cord alone, without involving the brain, allowing for quicker responses.
The ventral roots contain somatic motor fibers from ventral horn motor neurons and autonomic motor fibers from the lateral horns.
True
False
True.
Explanation: The ventral roots of the spinal cord carry motor (efferent) fibers from the ventral horn motor neurons (somatic) and lateral horn neurons (autonomic).
Ganglia are collections of nerve cell bodies found in the PNS.
True
False
True.
Explanation: Ganglia are structures containing nerve cell bodies, located in the peripheral nervous system (PNS).
Most ventral rami branch and rejoin one another lateral to the vertebral column to form structures called plexuses.
True
False
True.
Explanation: Ventral rami of spinal nerves form plexuses (e.g., cervical plexus, brachial plexus), which are networks of intersecting nerves.
