Autonomic Nervous System Quiz

Nervous System Overview

• The nervous system is responsible for controlling the body's functions.
• It includes both the central nervous system (CNS) and the peripheral nervous system (PNS).
• The CNS consists of the brain and spinal cord.
• The PNS connects the CNS to the rest of the body.

Objectives

• Identify brain lobes, sulci, and gyri.
• Understand functional localization in the brain.
• Describe basal nuclei and diencephalon functions.
• Differentiate types of cerebral white matter.
• Identify and describe brain stem functions.
• State cerebellum functions.
• Describe spinal cord structure (internal and external).
• Understand spinal nerve structure.
• Describe major nerve plexuses and their branches.
• Differentiate between sympathetic and parasympathetic divisions of the nervous system.

General Organization of the CNS

• The CNS is composed of the cerebrum, diencephalon, cerebellum, and brainstem.
• The cerebrum controls higher mental functions.
• The diencephalon links the cerebrum with the brain stem.
• The cerebellum coordinates body movements.
• The brainstem connects the cerebrum and cerebellum to the spinal cord and controls important functions.

Cerebrum

• The cerebrum is the largest part of the brain.
• It controls higher mental functions.
• The cerebral hemispheres are divided by a longitudinal fissure.
• Each hemisphere consists of grey matter (cell bodies of neurons) forming the cortex and white matter (axons of neurons) forming tracts.
• The cortex is folded into gyri and sulci to increase its surface area.

Cerebral Cortex

• The folded surface of the cortex increases surface area.
• Elevated folds are called gyri.
• Shallow depressions or grooves are called sulci.
• Deeper grooves or fissures divide the brain into lobes.

Grooves and Lobes of the Cerebrum

• The brain has four major lobes: frontal, parietal, temporal, and occipital.
• The central sulcus separates the frontal and parietal lobes.
• The lateral fissure separates the frontal and temporal lobes.

Functional Areas of the Cerebrum

• Different areas of the brain perform specific functions.
• The primary motor cortex controls voluntary movement.
• The primary somatosensory cortex receives sensory information from the body.
• Association areas are involved in higher-level functions like working memory, problem-solving, and language.

Deep Grey Matter: Basal Nuclei

• The basal nuclei assist in the regulation of voluntary motor activities.
• They modify instructions sent to skeletal muscles.
• Lesions to the basal nuclei can cause Parkinson's disease.

Deep Grey Matter: Diencephalon

• The diencephalon lies beneath the cerebrum.
• It links the cerebrum to the brainstem.
• Three main divisions are the thalamus, hypothalamus, and epithalamus.

Cerebral White Matter

• Commissural fibers connect both cerebral hemispheres (e.g., corpus callosum).
• Projection fibers connect the cerebrum with lower CNS centers.
• Association fibers connect areas within the same hemisphere.

Brainstem

• The brainstem includes the midbrain, pons, and medulla oblongata.
• It processes information between the spinal cord and cerebrum/cerebellum.
• It contains nuclei for cranial nerves and vital centers.
• The reticular formation is involved in consciousness.

Cerebellum

• The cerebellum is the second-largest part of the brain.
• It coordinates smooth body movements and maintains balance and posture.

Protections of the Brain

• The skull protects the brain.
• Meninges (dura, arachnoid, and pia mater) are membranes that surround the brain and spinal cord.
• Cerebrospinal fluid cushions the brain.

Blood Supply to the Brain

• Internal carotid arteries supply blood to the cerebrum and diencephalon.
• Vertebrobasilar system supplies blood to the brainstem, cerebellum, and spinal cord.

Spinal Cord: Overview

• The spinal cord is shorter than the vertebral column.
• It extends from the medulla oblongata to the lumbar region (dural sac).
• The lumbar cistern is located below L2 between the spinal cord termination and the coccyx, it's important for collecting and analyzing spinal fluid.
• CSF is located in the subarachnoid space, which provides cushion and protection.

External Features of the Spinal Cord

• The spinal cord terminates as the conus medullaris at vertebral level L2.
• Caudal nerves form the cauda equina.
• Pial extension forms the filum terminale.

Spinal Cord: Overview

• Spinal nerves emerge from the spinal cord.
• There are 31 pairs of spinal nerves.
• Spinal nerves are mixed nerves (contain both sensory and motor fibers).

Spinal Nerves

• The spinal cord segments have different spinal nerves that come out and branch off.
• Each nerve pair supplies particular sections of the body.

Internal Features of the Spinal Cord

• The spinal cord has a central canal surrounded by gray matter (nerve cell bodies) and white matter (nerve fibers).
• The gray matter is organized into dorsal (posterior), lateral, and ventral (anterior) horns.

CNS Major Tracts in the CNS

• Ascending tracts carry sensory information to the brain.
• Descending tracts carry motor information from the brain.
• Interneurons process and integrate the information throughout the CNS.

Structure of a Nerve

• A nerve is a bundle of neuron fibers surrounded by connective tissues.
• Each fiber is within endoneurium.
• Groups of fibers are called fascicles, surrounded within perineurium.
• Fascicles bundle together to form nerves and are bound by epineurium.

Cranial Nerves

• There are 12 pairs of cranial nerves.
• Cranial nerves vary in function (somatic sensory, somatic motor, or mixed function).

Distribution of Cranial Nerves

• Each cranial nerve has a specific origin and function in the body.
• Sensory information from sensory receptors is carried and processed and directed to the correct area of the brain.
• Testing can determine each nerve's function.

Dermatomes and Myotomes

• Dermatomes are areas of skin innervated by a spinal nerve.
• Myotomes are groups of muscles innervated by a spinal nerve.
• Damage to a spinal nerve affects a specific dermatome or myotome, this can be used for diagnostic uses.

Nerve Plexuses

• Spinal nerves combine to form nerve plexuses in the limbs.
• The plexuses help distribute nerve signals.
• The different nerve plexus supply different parts of the body.

Major Nerves of the Upper Limb

• Axillary, radial, musculocutaneous, ulnar, and median nerves supply sensation and motor to different sections of the arm, hand etc.

Major Nerves of the Lower Limb

• Femoral, lateral femoral cutaneous, obturator, anterior femoral cutaneous, and saphenous nerves supply sensation and motor to sections of the leg, thigh etc.

Overview of the Autonomic Nervous System

• The autonomic nervous system regulates involuntary bodily activities.
• It has two branches: sympathetic and parasympathetic.
• The sympathetic system prepares the body for stress while the parasympathetic system helps calm the body.

Divisions of Peripheral Nervous System

• The peripheral nervous system consists of somatic and autonomic systems.
• The somatic nervous system controls skeletal muscles.
• The autonomic nervous system regulates involuntary functions.

Somatic Nervous System vs. Autonomic Nervous System

• The somatic nervous system has one neuron between the CNS and effector organ(the muscle) while the ANS has two.
• The ANS has preganglionic and postganglionic neurons.
• The ANS is responsible for visceral reflexes by activating smooth muscles, cardiac muscles, and glands.

Overview of Preganglionic and Postganglionic Neurons

• Preganglionic neurons originate in the CNS (brain stem or spinal cord) and synapse with postganglionic neurons in ganglia.
• Postganglionic neurons transmit signals to effector cells (muscles or glands).

Divisions of Autonomic Nervous System

• The autonomic nervous system has two divisions: sympathetic and parasympathetic.
• These divisions regulate the body's various involuntary functions by releasing different neurotransmitters.

Structure of the Autonomic Nervous System

• The sympathetic and parasympathetic branches work together to regulate various organs.
• Each branch has different functions.
• The two branches often have opposing effects on target organs.

Parasympathetic

vs. Sympathetic Nervous System

• The parasympathetic nervous system is responsible for calming the body.
• The sympathetic nervous system prepares the body for action.
• The two systems work together maintaining homeostasis.

Anatomy of Parasympathetic Division I

• Preganglionic neurons are located in cranial nerve nuclei and spinal cord segment S2 to S4.
• Also called craniosacral division.
• Cranial nerves III, VII, IX, and X are involved.

Anatomy of Parasympathetic Division II

• Preganglionic neurons in the cranial region travel with cranial nerve fibers.
• Preganglionic neurons in the sacral region form pelvic splanchnic nerves exiting the spinal cord.
• Postganglionic neurons synapse within the wall of various visceral organs.

Function of Parasympathetic Division

• The parasympathetic branch is associated with restorative physiological tasks, such as slowing down the heart rate and stimulating digestion.
• Body systems and organs are affected by the release of acetylcholine, the main neurotransmitter.

Anatomy of the Sympathetic Division

• Preganglionic neurons are located in the spinal cord gray matter from segments T1 to L2.
• Also called the thoracolumbar division.
• Preganglionic neurons exit the spinal cord and travel to the sympathetic trunk ganglia.
• Postganglionic neurons re-enter the spinal nerve.

Function of Sympathetic Division

• The sympathetic branch is associated with preparing the body for stress responses.
• The sympathetic nervous system is responsible for releasing norepinephrine, the main neurotransmitter.

Sympathetic Pathways

• A two-neuron chain of sympathetic cells (pre and postganglionic) connects the brain and spinal cord to organs.
• Preganglionic neurons exit the spinal cord.
• Postganglionic neuron travels to organs through different routes that result in specific effects. (e.g., synapse with adrenal medulla).

Test your knowledge on the autonomic nervous system and its functions. This quiz covers topics such as the sympathetic division, peripheral nervous system, and spinal cord anatomy. Perfect for students studying anatomy or neuroscience.