Peripheral Nervous System: Brachial Plexus OT 505

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Questions and Answers

What is the primary function of the peripheral nervous system?

To process information within the brain

To generate reflex actions

To connect the body to the central nervous system (correct)

To protect the spinal cord

Which spinal nerves form the brachial plexus?

L1-S5

C5-T1 (correct)

T1-T12

C1-C4

What structures arise directly from the roots of the brachial plexus?

Long Thoracic nerve and Dorsal Scapular nerve (correct)

Axillary nerve and Radial nerve

Rhomboids and Latissimus Dorsi

Musculocutaneous nerve and Median nerve

How many cords are formed in the brachial plexus?

3 Signup and view all the answers

Which of the following nerves exclusively innervates the diaphragm?

Phrenic nerve Signup and view all the answers

What is the correct mnemonic to remember the branches of the brachial plexus?

Read The Darn Cadaver Book Signup and view all the answers

Which group of spinal nerves is categorized under the lumbosacral plexus?

L1-S5 Signup and view all the answers

Which component of the brachial plexus does NOT exist?

4 Cords Signup and view all the answers

What is the primary role of anterior rami in spinal nerves?

Join together to form plexuses Signup and view all the answers

Which branch of the brachial plexus is responsible for innervating the muscles of the upper limb?

All of the above Signup and view all the answers

What is the primary function of the nerves arising from the anterior divisions of the brachial plexus?

Supply muscles of the anterior compartments (flexors) Signup and view all the answers

Which nerve is responsible for innervating the Pectoralis Major from the lateral cord?

Lateral pectoral nerve Signup and view all the answers

Which muscle is NOT innervated by the Radial nerve?

Biceps Brachii Signup and view all the answers

What are the three cords of the brachial plexus named after?

Their position relative to the axillary artery Signup and view all the answers

Which trunk of the brachial plexus contributes to the Innervation of the Supraspinatus and Infraspinatus?

Superior (Upper) Trunk Signup and view all the answers

Which nerve innervates the Teres Major muscle?

Lower subscapular nerve Signup and view all the answers

What happens to the trunks of the brachial plexus just distal to the clavicle?

They divide into anterior and posterior divisions Signup and view all the answers

Which nerve arises from the posterior cord and innervates the Latissimus Dorsi?

Thoracodorsal nerve Signup and view all the answers

Which two nerves arise from the medial cord and their main targets?

Medial pectoral nerve; pectoralis major and minor muscles Signup and view all the answers

What is the origin of the C8 and T1 roots in the brachial plexus?

Neck of the first rib Signup and view all the answers

Study Notes

Peripheral Nervous System Overview

Composed of nervous tissue outside the vertebral canal and brainstem.
Connects the body to the central nervous system (CNS).
Includes cranial nerves and spinal nerves.

Spinal Nerve Components

Spinal nerves include 8 cervical, 12 thoracic, 5 lumbar, 5 sacral, and 1 coccygeal nerve.

Plexus Formation

Anterior rami of spinal nerves other than thoracic join to form plexuses.
Three major plexuses:
- Cervical Plexus (C1-C4): Primarily innervates neck muscles.
- Brachial Plexus (C5-T1): Supplies muscles of the upper limb.
- Lumbosacral Plexus (L1-S5): Supplies muscles of the lower limb.
Thoracic nerves remain as intercostal nerves.

Cervical Plexus Details

Formed from C1-C4 spinal nerves.
Key branches include:
- C2: Sternocleidomastoid.
- C3 & C4: Trapezius.
- C3-C5: Levator Scapulae.
- C4: Anterior Scalene.
- C3-C4: Middle Scalene.
- C3-C5: Phrenic nerve for diaphragm innervation.

Brachial Plexus Structure

Formed by the anterior rami of C5-T1 spinal nerves.
Composed of:
- 5 Roots.
- 3 Trunks: Superior (C5-6), Middle (C7), Inferior (C8-T1).
- 6 Divisions: Anterior and posterior.
- 3 Cords: Lateral, posterior, medial.
- 5 Terminal branches: Musculocutaneous, axillary, radial, median, ulnar.
Mnemonic for branches: "Read The Darn Cadaver Book."

Brachial Plexus Pathway

Located between the anterior and middle scalene muscles alongside the subclavian artery and vein.
Roots: C5-6, C7, C8-T1.
Nerves emerging from roots:
- Dorsal scapular nerve (C5): Innervates rhomboids and levator scapulae.
- Long thoracic nerve (C5, C6, C7): Innervates serratus anterior.

Trunks and Their Nerves

Trunks formed from roots:
- Superior (C5-C6): Suprascapular nerve (innervates supraspinatus, infraspinatus), subclavius nerve (innervates subclavius).
- Middle (C7): No specific branches detailed.
- Inferior (C8-T1): No specific branches detailed.

Divisions and Their Functions

Trunks divide into anterior and posterior divisions just distal to the clavicle.
Anterior divisions supply flexor (anterior compartment) muscles.
Posterior division supplies extensor (posterior compartment) muscles.
No specific nerves emerge from divisions.

Cords and Associated Nerves

Named based on their position relative to the axillary artery.
Lateral cord:
- Lateral pectoral nerve (innervates pectoralis major).
Medial cord:
- Medial pectoral nerve (innervates pectoralis major and minor).
Posterior cord:
- Upper subscapular nerve (innervates subscapularis).
- Thoracodorsal nerve (innervates latissimus dorsi).
- Lower subscapular nerve (innervates subscapularis and teres major).

Terminal Branches

Musculocutaneous, axillary, median, radial, ulnar nerves emerge from the cords.

Nerve Innervations

Axillary nerve: Innervates deltoid, teres minor, long head of triceps.
Musculocutaneous nerve: Innervates biceps brachii, brachialis, coracobrachialis.
Radial nerve: Innervates triceps, anconeus, brachioradialis.

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Description

This quiz covers the peripheral nervous system, specifically focusing on the brachial plexus. It examines the structure and function of cranial and spinal nerves, including their role in connecting the body to the central nervous system. Perfect for students in OT 505, the quiz will help reinforce key concepts related to nerve formation and organization.