Human Anatomy Quiz on Nerves and Plexuses

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Questions and Answers

Which nerve is responsible for innervating the diaphragm?

Radial nerve

Phrenic nerve (correct)

Obturator nerve

Axillary nerve

Which plexus originates from spinal nerves C5 to T1?

Cervical plexus

Thoracic plexus

Brachial plexus (correct)

Lumbosacral plexus

What is the function of the musculocutaneous nerve?

Innervates muscles of the medial thigh

Innervates the anterior arm muscles (correct)

Innervates the lateral leg muscles

Innervates the diaphragm

How many pairs of spinal nerves are there?

31 Signup and view all the answers

Which nerve innervates most of the intrinsic hand muscles?

Ulnar nerve Signup and view all the answers

What primary function does the pons serve in the brain?

Facilitating communication between the cerebrum and cerebellum Signup and view all the answers

Which structure is primarily responsible for sensory information relay, excluding smell?

Thalamus Signup and view all the answers

What is the role of the inferior colliculi in the midbrain?

Auditory nerve pathway relay Signup and view all the answers

Which function is NOT associated with the hypothalamus?

Gating sensory information Signup and view all the answers

What happens if the reticular formation is damaged?

Loss of consciousness and potential coma Signup and view all the answers

What does the pineal gland primarily influence?

Onset of puberty and long-term cycles Signup and view all the answers

Which function is attributed to the reticular activating system?

Arousing and maintaining consciousness Signup and view all the answers

Which of the following is NOT a homeostatic mechanism regulated by the hypothalamus?

Control of motor functions Signup and view all the answers

What is the main neurotransmitter of the sympathetic autonomic nervous system?

Norepinephrine Signup and view all the answers

Which division of the autonomic nervous system is responsible for conserving and restoring energy?

Parasympathetic Division Signup and view all the answers

Which of the following activities is primarily regulated by the parasympathetic autonomic nervous system?

Digestion of food Signup and view all the answers

What part of the brainstem controls basic reflex actions such as vomiting and sneezing?

Medulla Oblongata Signup and view all the answers

Which type of neurons connect the digestive tract to the central nervous system?

Sensory neurons Signup and view all the answers

What is the function of the vasomotor centers located in the medulla oblongata?

Regulate blood pressure Signup and view all the answers

Which autonomic ganglia are responsible for synapsing preganglionic neurons with postganglionic neurons?

Sympathetic ganglia Signup and view all the answers

What does the term 'fight-or-flight' refer to in the context of the autonomic nervous system?

Preparation for action Signup and view all the answers

Study Notes

Reflex Action

Predictable, automatic response to specific stimuli.
Involves five steps: reception, transmission to CNS, integration, transmission to muscles, and execution of response.

Spinal Cord Reflexes

Knee-Jerk Reflex: A simple stretch reflex indicating the functional state of higher CNS centers.
Withdrawal Reflex: Also known as flexor reflex, designed to remove limbs from painful stimuli.

Ascending Tracts

Carry impulses from the periphery to the brain.
Spinothalamic Tract: Transmits sensations of pain, light touch, and deep pressure.
Dorsal Column: Responsible for proprioception, touch, deep pressure, and vibration.
Spinocerebellar Tracts: Convey proprioceptive information to the cerebellum.

Descending Tracts

Carry impulses from the brain to the periphery.
Lateral Corticospinal: Involved in muscle tone and skilled movements, especially in the hands.
Anterior Corticospinal: Focuses on muscle tone and movement for trunk muscles.
Rubrospinal: Coordinates movements.
Reticulospinal: Adjusts posture.
Vestibulospinal: Balances posture and stability.
Tectospinal: Coordinates movements in response to visual stimuli.

Cranial Nerves

Transmit information from sensory receptors to the brain.
I. Olfactory: Smell.
II. Optic: Vision.
III. Oculomotor: Controls eye muscles and pupil constriction.
IV. Trochlear: Innervates one extrinsic eye muscle.
V. Trigeminal: Sensory for face and teeth; motor for mastication.
VI. Abducens: Innervates one extrinsic eye muscle.
VII. Facial: Taste sensation; controls facial muscles, salivary, and tear glands.
VIII. Vestibulocochlear: Responsible for hearing and balance.
IX. Glossopharyngeal: Taste and touch in the back of the tongue; pharyngeal muscle control.
X. Vagus: Sensory from pharynx, larynx, and viscera; motor and parasympathetic functions in thorax and abdomen.
XI. Accessory: Controls neck and upper back muscles.
XII. Hypoglossal: Innervates tongue muscles.

Spinal Nerves

Total of 31 pairs of mixed nerves along the spinal cord.
Comprised of 8 cervical, 12 thoracic, 5 lumbar, 5 sacral, and 1 coccygeal pairs.
Mixed nerves include both sensory and motor neurons.
Plexuses: Networks where spinal nerves intersect.
- Cervical Plexus
- Brachial Plexus
- Lumbosacral Plexus

Cervical Plexus

Formed from spinal nerves C1 to C4.
Phrenic Nerve: Key branch that innervates the diaphragm, essential for breathing.

Brachial Plexus

Derived from spinal nerves C5 to T1.
Axillary Nerve: Innervates shoulder muscles and skin.
Median Nerve: Supplies anterior forearm and intrinsic hand muscles.
Radial Nerve: Innervates muscles in the posterior arm and forearm; supplies sensory for the back of the arm and hand.
Musculocutaneous Nerve: Supplies anterior arm muscles and skin on the forearm's radial side.
Ulnar Nerve: Innervates most anterior forearm muscles and some intrinsic hand muscles; sensory for the hand's ulnar side.

Lumbosacral Plexus

Originates from spinal nerves L1 to S4.
Obturator Nerve: Innervates medial thigh muscles.
Femoral Nerve: Supplies anterior thigh muscles and skin on medial leg.
Tibial Nerve: Innervates posterior thigh muscles and foot muscles; sensory for the soles of the feet.
Common Fibular Nerve: Supplies lateral thigh and leg muscles; sensory for the anterior leg and dorsal foot.
Sciatic Nerve: Encases tibial and common fibular nerves.

Autonomic Nervous System

Involves preganglionic neurons and associated ganglia for involuntary control over body functions.

Autonomic Ganglia

Preganglionic neurons synapse with postganglionic neurons in autonomic ganglia.

Sympathetic ANS

Known as 'fight-or-flight' response, preparing the body for immediate action.
Active during stressful situations; increases heart rate (HR), blood pressure (BP), respiration, and releases glucose.
Main neurotransmitter is norepinephrine.

Parasympathetic ANS

Functions to conserve and restore energy; assists in returning the body to resting states.
Active during calm and restful periods; promotes involuntary activities like digestion, defecation, and urination.
Acetylcholine is the key neurotransmitter; fibers are found in the vagus nerve.

Autonomic Neurotransmitters

Acetylcholine: Principal neurotransmitter of the parasympathetic division.
Norepinephrine: Primary neurotransmitter for postganglionic neurons of the sympathetic division.

Functions of the Autonomic Nervous System

Sympathetic Division: Prepares for action; increases HR, BP, respiration, and glucose release.
Parasympathetic Division: Regulates involuntary activities at rest, such as digestion and waste elimination.

Enteric Nervous System

Comprises nerve plexus within the digestive tract wall.
Consists of sensory neurons, sympathetic & parasympathetic neurons, and enteric neurons.
Capable of regulating the digestive system independently of the CNS.

Brain Overview

Weighs approximately 3 pounds; contains around 25 billion neurons.
Highly complex organ requiring a continuous supply of oxygen and glucose.

Brainstem

Connects spinal cord with the brain; crucial for regulating heart rate, blood pressure, and breathing.
Medulla Oblongata: Vital for reflex actions; contains cardiac, vasomotor, and respiratory centers.
Pons: A bridge for cerebrum-cerebellum communication; regulates respiration and sleep.
Midbrain: Smallest brainstem part; contains colliculi for auditory and visual reflexes.
Reticular Formation: Regulates motor functions; key for arousal and consciousness.

Diencephalon

Located between the brainstem and cerebrum; contains important relay stations.
Thalamus: Major relay center for sensory information (except smell) to cerebrum; influences mood and pain perception.
Epithalamus: Houses pineal gland and nuclei involved in emotional responses to odors; affects puberty onset and circadian rhythms.
Hypothalamus: Regulates homeostasis; controls body temperature, hunger, thirst, and emotional responses.

Important Homeostatic Mechanisms

Acts as control center for the ANS and links nervous and endocrine systems.
Maintains fluid balance through anti-diuretic hormone (ADH) that regulates kidney water excretion.
Regulates body temperature, food intake, sleep-wake cycles, sexual behavior, and emotional responses.

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Description

Test your knowledge on the human nervous system with this quiz focused on key nerves and plexuses. Questions range from the innervation of the diaphragm to the musculocutaneous nerve. Challenge yourself and learn about the spinal nerves and their functions!