(4.1) ANS I (OVERVIEW OF ANS) & ANS II (SYMPATHETIC NS)

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Questions and Answers

What is the primary pathway for postganglionic neurons to exit the sympathetic trunk in the spinal region T1 to L2?

They leave via the anterior ramus directly.

They exit through the posterior ramus.

They ascend to higher cervical regions before exiting.

They enter the gray rami communicans. (correct)

Which divisions of the sympathetic nervous system provide visceral motor functions to the thoracic and abdominopelvic cavities?

Parasympathetic and central divisions

Cutaneous and visceral divisions

Cervical and sacral divisions

Sympathetic visceral division (correct)

Which type of ganglia are primarily involved in synapsing splanchnic nerves for abdominal and pelvic viscera?

Celiac ganglia

Dorsal root ganglia

Prevertebral ganglia (correct)

Paravertebral ganglia

What is the significance of gray rami communicans in the sympathetic pathway?

They allow postganglionic sympathetic fibers to rejoin spinal nerves. Signup and view all the answers

Which pathway is specifically associated with descending sympathetic pathways for lower limb innervation?

They descend the sympathetic trunk, synapse, and exit via gray rami. Signup and view all the answers

What type of neurons do postganglionic neurons join or form to reach their target tissues?

Spinal or cranial nerves and splanchnic nerves Signup and view all the answers

Which of the following is primarily associated with the parasympathetic nervous system?

Stimulates digestive activity Signup and view all the answers

Which of the following correctly describes the synaptic pathway for sympathetic innervation to the skin?

Synapse at the sympathetic paravertebral ganglia and travel with spinal nerves Signup and view all the answers

What distinguishes the sympathetic trunk's afferent pathways from prevertebral ganglia?

Prevertebral ganglia serve the abdominal and pelvic organs Signup and view all the answers

Which of the following organs receives sympathetic innervation but has no identified parasympathetic counterpart?

Adrenal gland Signup and view all the answers

In which of the following situations would sympathetic nervous system activation most likely occur?

During exercise or stress Signup and view all the answers

From which sections of the spinal cord do sympathetic fibers primarily originate?

Thoracolumbar region, specifically T1-L2 Signup and view all the answers

What is the primary function of the parietal division of the sympathetic nervous system?

To provide visceral motor to glands and smooth muscles in the skin Signup and view all the answers

Which pathway should a preganglionic neuron take to reach the sympathetic trunk?

Intermediolateral column, anterior root, anterior rami, sympathetic trunk Signup and view all the answers

What types of muscles or glands are innervated by the visceral motor functions of the sympathetic system?

Smooth muscles in skin and glands such as sweat glands Signup and view all the answers

In which areas are the sympathetic trunk ganglia located?

In the T1-L2 level of the spinal cord Signup and view all the answers

Which of these best describes the structure of the sympathetic nervous system's route from preganglionic to postganglionic neurons?

They enter the sympathetic trunk and can either synapse immediately or ascend/descend before synapsing Signup and view all the answers

What is the function of gray rami communicans in the sympathetic pathway?

To connect spinal nerves to sympathetic ganglia Signup and view all the answers

If a signal enters the sympathetic trunk, but needs to innervate structures at a higher level, what pathway will it take?

It ascends the trunk, synapses, and then leaves the trunk Signup and view all the answers

What sensory information does the visceral division of the sympathetic system receive?

Visceral sensory from thoracic and abdominal pelvic organs Signup and view all the answers

What happens to preganglionic neurons once they enter the sympathetic trunk?

They synapse with postganglionic neurons and then exit at the same level or travel to different levels Signup and view all the answers

Which division of the sympathetic nervous system is responsible for the vasomotion, sudomotion, and pilomotion in the skin?

Parietal Division Signup and view all the answers

What is a key role of neural crest cells in the development of the peripheral nervous system?

They migrate to create both cranial and spinal ganglia. Signup and view all the answers

During which developmental week does the sympathetic nervous system begin to form?

Week five Signup and view all the answers

What structures are formed as the axons grow out from the neuronal cell bodies in the ganglia?

Connections to effector organs Signup and view all the answers

Which type of ganglia are primarily involved in the sympathetic nervous system's organization?

Prevertebral and paravertebral ganglia Signup and view all the answers

What is one of the main functions of the axons that emerge from sympathetic ganglia?

To innervate target tissues and organs Signup and view all the answers

What is the primary function of the axons growing from the neuronal cell bodies during the development of the sympathetic nervous system?

To grow towards the anterior ramus for motor innervation Signup and view all the answers

Which structure serves as a synapsing point for axons heading to the skin from the sympathetic trunk?

Gray ramus Signup and view all the answers

How do preganglionic axons exit the sympathetic trunk to innervate thoracic organs?

Via splenchnic nerves Signup and view all the answers

What role do sympathetic trunk ganglia play in the sympathetic nervous system?

They are sites for synapsing postganglionic neurons Signup and view all the answers

Which of the following provides the pathway for axons to travel to abdominal and pelvic organs?

Sympathetic trunk Signup and view all the answers

Which type of cells are responsible for myelinating axons in the peripheral nervous system, aiding in efficient signal transmission?

Schwann cells Signup and view all the answers

What is the primary action of axons growing into the sympathetic trunk during development?

To synapse with postganglionic neurons Signup and view all the answers

What is the primary role of neural lemocytes in the structure of nerves?

To provide insulation for axons Signup and view all the answers

Which component supports the neurons in a sympathetic ganglion?

Satellite cells Signup and view all the answers

What type of cells wrap around a nerve to form myelin sheaths?

Neural lemocytes Signup and view all the answers

Which structure is primarily associated with the sympathetic nervous system's response to stress or danger?

Adrenal gland Signup and view all the answers

Which characteristic is notable for neurons observed in sympathetic ganglia?

They contain large cell bodies Signup and view all the answers

What role do satellite cells play in the sympathetic ganglia?

They support and maintain neuronal cells Signup and view all the answers

During sympathetic activation, what physiological changes occur in addition to increased heart rate?

Dilation of pupils Signup and view all the answers

Which glial cell type is responsible for forming the myelin sheath in the peripheral nervous system?

Schwann cells Signup and view all the answers

What is a key factor in the growth and repair of neuronal axons?

Presence of Schwann cells Signup and view all the answers

Which type of ganglia are found in the sympathetic nervous system and serve as relay points for nerve signals?

Sympathetic ganglia Signup and view all the answers

Study Notes

Autonomic Nervous System: Introduction

The course learning objective is to describe how the body communicates with itself using the nervous system's anatomical structures and pathways for better medical diagnoses when systems are compromised.

Lecture Learning Objectives

Describe the role and similarities/differences of the autonomic nervous system compared to the peripheral nervous system.
Map/diagram how the ANS communicates, including the spinal cord, preganglionic neurons, postganglionic neurons, and effector organs.
Describe the differences between the sympathetic and parasympathetic nervous systems, focusing on response, effect on structures/systems, CNS contributions, and location/name of ganglia involved.
Diagram preganglionic and postganglionic fibers of the sympathetic and parasympathetic systems, comparing and contrasting anatomical differences and fiber lengths.

ANS - What Does It Do?

Involuntary system that controls/monitors the body's internal environment.
Primarily works via motor innervation:
- Smooth muscle (involuntary)
- Modified cardiac muscle
- Glandular cells
Sensory (afferent) function:
- Travels alongside motor nerves
- Involved in autonomic reflexes, conducting visceral pain, and regulatory function.

How Does It Communicate?

Pathways involve a series of two neurons:
- Preganglionic (presynaptic)
- Postganglionic (postsynaptic)
- Multipolar = motor; unipolar = sensory

Sympathetic vs. Parasympathetic

Sympathetic: Activated in emergency situations, responsible for catabolic "fight-or-flight" response, and regulates vessels via vasomotion.
Parasympathetic: Responsible for bringing the body to homeostasis, characterized by anabolic "rest and digest" functions.

Organ-Specific Response Comparison (Sympathetic vs. Parasympathetic)

Organ-specific tables comparing sympathetic and parasympathetic responses (including eyes, skin, lacrimal/salivary glands, heart, blood vessels, and lungs).

Anatomical Distinction - CNS Contributions

Sympathetic (thoracolumbar):
- Enters sympathetic trunk via spinal nerves T1-L2.
- May travel in sympathetic trunk to a specific level affecting skin, glands/organs, or abdominal organs.
Parasympathetic (craniosacral):
- Leaves CNS via cranial nerves III, VII, IX, and X.
- Synapses in autonomic ganglia within the crania, or the sacral spinal nerves S2-S4 synapsing in intramural ganglia near or within organs.

Anatomical Distinction - Location of Ganglia

Sympathetic: Paired, vertically-oriented structures alongside the vertebral column in the neck, thorax, and abdomen (paravertebral ganglia). Prevertebral ganglia are single and located in the abdominal cavity near major arteries.
Parasympathetic: Cranial ganglia (ciliary, otic, submandibular, pterygopalatine) and intramural/terminal ganglia located near or within target organs.

Sympathetic and Parasympathetic Fibers

[Note: No specific content provided here; this is a placeholder for details about these fibers]

ANS II - Sympathetic Nervous System

[Note: Course learning objective concerning the body's communication via this system is repeated.]

Lecture Learning Objectives (ANS II - Sympathetic Nervous System)

Visually identify sympathetic structures on a diagram.
Review and diagram sympathetic structures involved in the body's response.
Trace/diagram the three parietal sympathetic pathways and their linkage to the cervical, brachial, and lumbosacral plexuses, linking spinal levels.
Trace and diagram the sympathetic pathways for the head, neck, and thoracic organs; including spinal levels, pathways, synapses, and organ effects.
Trace and diagram sympathetic pathways for the abdominopelvic viscera (spinal levels, splanchnic nerves, prevertebral ganglia, and effector organs).
Describe empathetic innervation to the suprarenal gland, and define mass activation and when it occurs.
Visually identify components of sympathetic ganglia histologically.
Describe sympathetic division development.

Sympathetic Visceral Motor

Where will UMNs start?
Which diencephalic structures play an important role?

Preganglionic Neurons

Cell bodies located in intermediolateral columns (nuclei) of spinal cord T1-L2.
Organizes somatotopically.

Postganglionic Neurons

Cell bodies located in paravertebral/sympathetic trunk chain or prevertebral ganglia.
All sympathetic ganglia are close to the spinal cord. Preganglionic fibers are short, and postganglionic fibers are long to reach all parts of the body.

Postganglionic Neurons (Detailed)

Further details about paravertebral ganglia (linked to form sympathetic trunks), one per vertebral body, and ganglion impar.
Prevertebral ganglia are part of nerve plexuses surrounding major branches of abdominal aorta, named for surrounding arterial branches (Celiac, superior mesenteric, aorticorenal, inferior mesenteric).

Sympathetic Divisions

[Note: Further questions and divisions are mentioned, but no detailed content given.]

Sympathetic Nervous System Divisions

Parietal Division: Provides visceral motor innervation to glands and smooth muscles in skin (sweat glands, smooth muscle in vessels, arrector pili muscles). Involved in vasomotion (vasoconstriction/dilation), sudomotortion (sweat) and pilomotion (goosebumps).
Visceral Division: Provides visceral motor to thoracic and abdominopelvic organs; receives visceral sensory from these organs.

Visceral Division - Possible Pathways

Three possibilities for visceral division pathways: a. Syanpsing immediately b. Ascending through trunk then synapsing c. Passing through trunk without synapsing, using splanchnic nerves and eventually synapsing at a prevertebral ganglion.

Head and Neck Viscera

Preganglionic fibers enter sympathetic trunk
Ascend then synapse in superior cervical ganglia (uppermost paravertebral ganglion).
Postganglionic fibers exit trunk (cephalic arterial ramus)
Travel along internal carotid artery to form internal carotid plexus.

Thoracic Organs

Sympathetic innervation to heart and lungs.
Preganglionic fibres ascend to superior, middle, or inferior cervical ganglia then synapse, or synapse in T1-T5 paravertebral ganglia.

Cardiopulmonary Splanchnic Nerves

Superior, Middle, and Inferior cervical ganglia as points of synapse or origin for preganglionic cardiopulmonary splanchnic nerves.

Gross Anatomy

Identification of key structures related to the ANS using diagrams
Diagrams of the aorta, celiac trunk, celiac ganglion, paravertebral ganglia, aorticorenal ganglia, superior mesenteric artery/ganglion, inferior mesenteric artery/ganglion, and prevertebral ganglia.

Abdominal and Pelvic Viscera

Detailed description of the pathways (passing through/without synapsing in the sympathetic trunk via splanchnic nerves; synapsing at prevertebral ganglia).

Prevertebral Ganglia

Prevertebral ganglia are not paired; located only in the abdominal cavity. Details provided about the spinal nerves and specific ganglia (Celiac, Lesser, Least, Superior, Inferior mesenteric).

The Exception: Suprarenal Gland

Preganglionic sympathetic fibers pass through prevertebral ganglia without synapsing, terminating on cells within the suprarenal medulla.
Suprarenal medulla cells function as postganglionic neurons, releasing neurotransmitters into the bloodstream (widespread response).

Mass Activation

Simultaneous innervation of many effector organs, occurring during emergency or crisis situations due to numerous branches of preganglionic sympathetic axons that synapse in many ganglia, thereby contacting many postganglionic neurons in many effector organs.

Histology and Development

[Note: No detailed information; it's listed as a section heading only.]

Sympathetic Histology

Images showing anatomical parts of sympathetic ganglia, including neuron cell bodies and satellite cells, neurolemmocytes (Schwann cells).

Development of the Sympathetic Division

Neural crest cells migrate along the spinal cord and aorta to create sympathetic trunk masses.
Other neural crest cells migrate to form prevertebral ganglia and associated plexuses.
Details on different stages and components involved in the process of development of the sympathetic division.

Studying That Suits You

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Description

This quiz covers key concepts related to the sympathetic nervous system, focusing on pathways, types of ganglia, and innervation in thoracic and abdominal regions. You'll explore the functions of postganglionic neurons, various ganglionic structures, and differences between sympathetic and parasympathetic systems.