Questions and Answers
The ______ nerve may result in median nerve palsy, causing numbness and pain in the palm and fingers.
median
The ______ plexus includes the triceps brachii and extensor muscles of the forearm.
brachial
Inability to pronate the forearm is a symptom of injury to the ______ nerve.
median
Damage to the ulnar nerve affects the muscles of the ______ and results in sensory loss on the medial side of the hand.
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The condition known as ______ scapula occurs when the scapula protrudes due to nerve injury.
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The roots of the brachial plexus are formed by the anterior rami of spinal nerves C5–C8 and ______.
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Injury to the superior roots of the brachial plexus may result from forceful pulling away of the head from the ______.
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The brachial plexus extends inferiorly and laterally on either side of the last four cervical and first thoracic ______.
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The ulnar nerve supplies the anteromedial muscles of the forearm and most of the muscles of the ______.
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The presentation of brachial plexus injury can occur from excessive stretching of an infant’s neck during ______.
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Study Notes
Brachial Plexus Overview
- Formed by anterior rami of spinal nerves C5–C8 and T1.
- Extends inferiorly and laterally from the last four cervical and first thoracic vertebrae.
- Passes above the first rib, posterior to the clavicle, and enters the axilla.
Key Nerves and Their Functions
-
Radial Nerve:
- Supplies triceps brachii, anconeus, extensor muscles of the forearm.
- Provides sensation to the skin of the posterior arm and forearm, lateral two-thirds of the dorsum of the hand, and proximal/middle phalanges.
-
Medial Pectoral Nerve:
- Innervates pectoralis major and pectoralis minor muscles.
-
Medial Cutaneous Nerve of Arm:
- Supplies skin of the medial and posterior aspects of the distal third of the arm.
-
Medial Cutaneous Nerve of Forearm:
- Innervates the skin of medial and posterior aspects of the forearm.
-
Ulnar Nerve:
- Innervates flexor carpi ulnaris, ulnar half of flexor digitorum profundus, and most hand muscles.
- Supplies skin of the medial side of the hand, little finger, and medial half of the ring finger.
Nerve Injuries and Effects
-
Median Nerve Injury:
- Can lead to median nerve palsy, causing numbness, tingling, and pain in the palm and fingers.
- Results in inability to pronate the forearm and flex the fingers; the arm cannot be abducted beyond horizontal.
-
Superior Roots Injury (C5–C6):
- Caused by forceful pulling away of the head from the shoulder.
- May occur from a fall on the shoulder or during childbirth, leading to Erb-Duchenne palsy (waiter's tip).
-
Winging of Scapula:
- Caused by injury leading to scapula protrusion; results in limited upper limb function.
Additional Nerve Functions and Branches
-
Lateral Cord Branches:
- Includes lateral pectoral nerve, musculocutaneous nerve.
-
Posterior Cord Branches:
- Contains axillary nerve, radial nerve.
-
Medial Cord Branches:
- Includes ulnar nerve, medial pectoral nerve, medial brachial cutaneous nerve.
Important Nerve Presentation
- Wrist Drop: Attributable to radial nerve injury.
- Ulnar Nerve Palsy: Affects hand functions.
These key points encapsulate the structural organization and clinical significance of the brachial plexus and its associated nerves.
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Description
Test your knowledge on the anatomy of the upper limb, focusing on the triceps brachii, anconeus, and extensor muscles. This quiz will also cover the sensory innervation of the skin in the posterior arm and forearm, as well as the dorsum of the hand. Perfect for students studying human anatomy or medical fields.
