Questions and Answers
Which spinal nerves form the Brachial Plexus?
What is the plexus that provides nerves for the muscles of the neck?
Which of the following is NOT a branch of the Brachial Plexus?
How many roots does the Brachial Plexus have?
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Which branches arise directly from the roots of the Brachial Plexus?
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What are the components of the Brachial Plexus after the roots?
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What structure does the Brachial Plexus run between?
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Which of the following is incorrect about the spinal nerves in the Peripheral Nervous System?
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What are the main trunks formed from the roots of the brachial plexus?
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Which nerve arises from the Superior trunk?
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What differentiates the medial and lateral cords of the brachial plexus?
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Which of the following nerves does NOT arise from the medial cord?
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Which nerve innervates the Biceps Brachii muscle?
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What is the function of the posterior cord in the brachial plexus?
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Which terminal branches are derived from the cords of the brachial plexus?
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Which of the following muscles is innervated by the Axillary nerve?
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Study Notes
Peripheral Nervous System Overview
- Comprises nervous tissue outside the vertebral canal and brainstem.
- Connects the peripheral body to the central nervous system.
- Includes cranial and spinal nerves:
- 8 Cervical
- 12 Thoracic
- 5 Lumbar
- 5 Sacral
- 1 Coccygeal
Plexus Formation
- Formed by anterior rami of spinal nerves joining and branching.
- Three major plexuses:
- Cervical Plexus (C1-C4): Innervates neck muscles.
- Brachial Plexus (C5-T1): Innervates upper limb muscles.
- Lumbosacral Plexus (L1-S5): Innervates lower limb muscles.
- Thoracic nerves remain as intercostal nerves without forming a plexus.
Cervical Plexus
- Anterior rami of C1-C4 form this plexus.
- Major branches include:
- C2: Sternocleidomastoid
- C3, C4: Trapezius
- C3-C5: Levator Scapulae
- C4: Anterior Scalene
- C3-C4: Middle Scalene
- C3-C5: Phrenic nerve (innervates diaphragm)
Brachial Plexus
- Formed from anterior rami of C5-T1 spinal nerves.
- Structure:
- 5 Roots: C5-C6, C7, C8-T1
-
3 Trunks:
- Superior (C5-C6)
- Middle (C7)
- Inferior (C8-T1)
- 6 Divisions: Anterior and Posterior
- 3 Cords: Lateral, Posterior, Medial
- 5 Branches: Musculocutaneous, Axillary, Radial, Median, Ulnar
- Mnemonic: "Read the darn cadaver book."
Brachial Plexus Pathway
- Runs deep to the clavicle between the anterior and middle scalene muscles.
- Initial formation includes superior, middle, and inferior trunks.
- Divides into anterior and posterior divisions just distal to the clavicle.
Roots of Brachial Plexus
- Two nerves arise directly from roots:
- Dorsal Scapular Nerve (C5): Innervates rhomboids and levator scapulae.
- Long Thoracic Nerve (C5, C6, C7): Innervates serratus anterior.
Trunks of Brachial Plexus
- Superior Trunk: C5-C6
- Middle Trunk: C7
- Inferior Trunk: C8-T1
- Trunks give rise to:
- Suprascapular Nerve: Innervates supraspinatus and infraspinatus.
- Subclavius Nerve: Innervates subclavius.
Divisions of Brachial Plexus
- Trunks separate into anterior (lateral and medial) and posterior divisions.
- Anterior divisions innervate flexor muscles of the anterior compartments.
- Posterior divisions innervate extensor muscles of the posterior compartments.
Cords of Brachial Plexus
- Named based on their position to the axillary artery:
- Lateral Cord
- Medial Cord
- Posterior Cord
Branches from the Cords
- 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 of Brachial Plexus
- Musculocutaneous: Innervates biceps brachii, brachialis, and coracobrachialis.
- Axillary: Innervates deltoid, teres minor, and long head of triceps.
- Radial: Innervates triceps, anconeus, and brachioradialis.
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Description
Dive into the intricacies of the peripheral nervous system focusing on the brachial plexus in this OT 505 quiz. Review essential concepts like the composition of cranial and spinal nerves, and understand the formation of nerve plexuses. Test your knowledge and grasp the connections between these systems.
