Peripheral Nervous System Quiz

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Questions and Answers

Which structure is primarily involved in innervating the anterior head region?

Dorsal rami of cervical spinal nerves

Trigeminal nerve (correct)

Cervical plexus

Vagus nerve

What is the role of pseudounipolar neurons in the peripheral nervous system?

They connect to the CNS and sensory receptors (correct)

They form the cranial nerves

They generate motor impulses

They exclusively innervate skeletal muscles

Which spinal nerve function is accurately described as autonomic?

Anterior branches of cervical spinal nerves (correct)

Dorsal rami of cervical spinal nerves

Motor fibers innervating skeletal muscles

Sensory fibers of spinal nerves

Dermatomes represent which aspect of spinal nerve function?

The region of body surface innervated by specific spinal nerves Signup and view all the answers

Which cranial nerve branch is responsible for innervating the green region of the head?

Ophthalmic nerve Signup and view all the answers

The vagus nerve primarily innervates which area?

Ear region Signup and view all the answers

What is the primary function of motor fibers in the peripheral nervous system?

To control skeletal muscle contraction Signup and view all the answers

Which statement regarding cranial nerves is correct?

Some cranial nerves possess autonomic functions Signup and view all the answers

Which term best describes the network formed by the anterior branches of cervical nerves?

Cervical plexus Signup and view all the answers

Which region does not receive innervation from the trigeminal nerve?

Plexus region Signup and view all the answers

What is the total number of cervical spinal nerves?

8 Signup and view all the answers

Which of the following statements about rami communicantes is true?

The grey ramus connects sympathetic ganglia to spinal nerves. Signup and view all the answers

In which spinal region do the nerves change their naming convention to take the name of the vertebra above them?

Thoracic region Signup and view all the answers

What is the primary function of the dorsal ramus?

Supplies posterior muscles and skin. Signup and view all the answers

Which cranial nerve is responsible for motor innervation to the muscles of facial expression?

Facial nerve (VII) Signup and view all the answers

What distinguishes spinal nerves from cranial nerves in terms of their structure?

Spinal nerves have a mixed function. Signup and view all the answers

Which plexus is responsible for innervating the lower limbs?

Sacral plexus Signup and view all the answers

Which region of the spinal cord does NOT form a nerve plexus?

Thoracic region Signup and view all the answers

What category do spinal nerves fall under regarding their function?

Mixed Signup and view all the answers

What do the ventral rami primarily supply?

Anterior and lateral muscles and skin Signup and view all the answers

Which muscles are innervated by the femoral nerve?

Sartorius and quadriceps femoris Signup and view all the answers

What is the primary motor function of the tibial portion of the sciatic nerve?

Innervates the muscles of the foot sole Signup and view all the answers

Which nerve has only sensory functions and innervates the skin on the posterior surface of the thigh and leg?

Posterior femoral cutaneous nerve Signup and view all the answers

Which nerve innervates the external anal sphincter and external urethral sphincter?

Pudendal nerve Signup and view all the answers

What is the primary function of the coccygeal plexus?

Innervates muscles of the anal region Signup and view all the answers

How do motor units differ depending on the muscles they serve?

Motor unit size is based on the need for strength versus precision. Signup and view all the answers

Which nerve is responsible for innervating the anterior thigh and medial leg skin?

Femoral nerve Signup and view all the answers

What type of functions do the superior and inferior gluteal nerves have?

Only motor functions Signup and view all the answers

Which portion of the sciatic nerve is responsible for innervating the anterior compartment of the leg?

Common fibular portion Signup and view all the answers

What characterizes the neuromuscular junction (NMJ)?

Signup and view all the answers

What is the primary function of the cervical plexus?

To innervate the diaphragm and hyoid muscles Signup and view all the answers

What defines the brachial plexus's serious role in orthopedics?

It encompasses nerves that innervate the upper limbs Signup and view all the answers

Which nerve is primarily responsible for the flexion of the forearm?

Musculocutaneous nerve Signup and view all the answers

What is a significant characteristic of thoracic nerves compared to other plexuses?

They have no branching structure Signup and view all the answers

Which nerve originates from the lumbar plexus and is deemed most important?

Femoral nerve Signup and view all the answers

What is the role of the median nerve in the hand's motor function?

Innervates the two lateral lumbricals Signup and view all the answers

What type of nerves are intercostal nerves classified as?

Thoracic nerves Signup and view all the answers

Which of the following correctly describes the role of the ulnar nerve?

Innervates the flexor carpi ulnaris Signup and view all the answers

What is a defining feature of the brachial plexus's structure?

It creates anterior and posterior divisions Signup and view all the answers

What sensory function does the radial nerve provide?

Posterior aspect of the arm and forearm Signup and view all the answers

Which muscle is NOT innervated by the femoral nerve?

Adductor longus Signup and view all the answers

What is the primary role of the posterior femoral cutaneous nerve?

Sensory innervation to the skin of the posterior thigh Signup and view all the answers

Which of the following statements about the sciatic nerve is true?

It is a mixed nerve with both tibial and common fibular portions. Signup and view all the answers

Which component of the sciatic nerve innervates the short head of biceps femoris?

Common fibular portion Signup and view all the answers

What is the function of the pudendal nerve?

Motor innervation to pelvic floor muscles Signup and view all the answers

Which nerve serves exclusively motor functions to the posterior pelvis?

Superior gluteal nerve Signup and view all the answers

What determines the size of a motor unit?

The number of muscle fibers controlled by a single neuron Signup and view all the answers

Which area is primarily innervated by the tibial nerve?

Muscles in the posterior compartment of the leg Signup and view all the answers

What is unique about the coccygeal plexus?

It is formed by S4 and coccygeal nerves. Signup and view all the answers

Which statement about the neuromuscular junction (NMJ) is accurate?

It connects a motor neuron to a muscle fiber during muscle contraction. Signup and view all the answers

Study Notes

Peripheral Nervous System (PNS) and the Local Motor System

The locomotor system operates in conjunction with the PNS, essential for movement.
Peripheral nerve lesions are common in traumatology due to their proximity to joints, muscles, and bones.
PNS is categorized into autonomic and somatic nervous systems.
Sensory fibers in the somatic system consist of pseudounipolar neurons in spinal ganglia, connecting periphery to the CNS.
Motor fibers originate in the CNS, projecting through peripheral nerves to innervate skeletal muscles.

Types of Nerves

Cranial Nerves:
- Originate in the brain, innervating the head, neck, and back.
- Not all are purely somatic; examples include autonomic nerves such as oculomotor (III), facial (VII), vagus (X), and glossopharyngeal (IX).
Spinal Nerves:
- Arise from the spinal cord, innervating the neck, trunk, and limbs; can be autonomic or somatic.
- There are 31 pairs: 8 cervical, 12 thoracic, 5 lumbar, 5 sacral, and 1 coccygeal.
- Dermatomes represent specific body regions innervated by each spinal nerve.

Innervation of the Head

The trigeminal nerve (V cranial) provides primary innervation for the anterior head, divided into three branches:
- Ophthalmic: Green region.
- Maxillary: Blue region.
- Mandibular: Red region.
The posterior head and ear regions are innervated by cervical spinal nerves' dorsal rami.
The cervical plexus, formed by the anterior cervical nerves, innervates the neck (purple region).

Spinal Nerve Structure

Spinal nerves split into dorsal and ventral roots:
- Dorsal Root: Contains sensory neuron bodies in spinal ganglia.
- Ventral Root: Contains motor neurons.
Upon exiting the vertebral column, spinal nerves form mixed nerves with sensory and motor fibers.

Communication and Rami

Rami communicantes link spinal nerves and sympathetic trunk ganlgia:
- Gray Ramus Communicans: Carries postganglionic fibers to effector organs.
- White Ramus Communicans: Transmits preganglionic fibers to sympathetic ganglia.

Nerve Plexuses

Ventral rami form nerve plexuses instead of running independently:
- Cervical Plexus: Innervates the head, neck, and shoulders.
- Brachial Plexus: Innervates chest, shoulders, arms, and hands.
- Lumbar Plexus: Innervates back, abdomen, groin, and legs.
- Sacral Plexus: Innervates pelvis, legs, and feet.
- Coccygeal Plexus: Innervates the coccygeal region.

Cervical Plexus

Formed from spinal nerves C1-C5, provides motor and sensory branches.
Key nerves include the phrenic nerve, innervating the diaphragm, and various cutaneous branches.

Brachial Plexus

Formed by C5-T1 spinal nerves, crucial for upper limb function.
Divided into trunks, divisions, cords, and terminal branches, including:
- Musculocutaneous Nerve: Innervates arm flexors.
- Median Nerve: Controls forearm and hand flexors.
- Radial Nerve: Innervates forearm extensors.
- Ulnar Nerve: Innervates hand muscles.

Lumbar Plexus

Originates from L1-L4 spinal nerves.
Key nerves include the femoral nerve (innervates anterior thigh) and obturator nerve (innervates medial thigh).

Sacral Plexus

Derived from L4-S3 spinal nerves, with the sciatic nerve being the largest.
Innervates lower limbs with separate tibial and common fibular portions.

Coccygeal Plexus

A small plexus formed by S4 and coccygeal nerves, innervating anal region muscles.

Neuromuscular Junction (NMJ)

Site of synapse between motor neuron and muscle fiber, facilitating muscle contraction.
Motor units consist of one motor neuron and all muscle fibers it controls.
The size of motor units varies depending on the required precision of movement; larger in back muscles, smaller in eye muscles to allow fine control.

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Description

Test your knowledge on the Peripheral Nervous System and its role in the locomotor system. This quiz covers cranial and spinal nerves, their functions, and their categorization into autonomic and somatic systems. Explore the essential connections between the nerves and movement.