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Questions and Answers
What is the brachial plexus?
What is the brachial plexus?
Which of the following spinal nerves does not contribute to the formation of the brachial plexus?
Which of the following spinal nerves does not contribute to the formation of the brachial plexus?
What is the correct order of the brachial plexus formation?
What is the correct order of the brachial plexus formation?
Which of the following nerves is not a terminal branch of the brachial plexus?
Which of the following nerves is not a terminal branch of the brachial plexus?
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What is a common symptom of brachial plexus injuries?
What is a common symptom of brachial plexus injuries?
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What is the primary method of diagnosis for brachial plexus injuries?
What is the primary method of diagnosis for brachial plexus injuries?
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What is the origin of the brachial plexus?
What is the origin of the brachial plexus?
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What is the most severe type of brachial plexus injury?
What is the most severe type of brachial plexus injury?
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What is a possible outcome of spontaneous recovery from brachial plexus injury?
What is a possible outcome of spontaneous recovery from brachial plexus injury?
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Which root is primarily responsible for motor function?
Which root is primarily responsible for motor function?
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What is the primary goal of surgical intervention in brachial plexus injuries?
What is the primary goal of surgical intervention in brachial plexus injuries?
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What is a common technique used in surgical repair of brachial plexus injuries?
What is a common technique used in surgical repair of brachial plexus injuries?
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What is the primary function of the C7 root?
What is the primary function of the C7 root?
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What is the expected outcome of rehabilitation for brachial plexus injuries?
What is the expected outcome of rehabilitation for brachial plexus injuries?
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What is the origin of the Pronator Teres muscle?
What is the origin of the Pronator Teres muscle?
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What is the action of the Flexor Carpi Radialis muscle?
What is the action of the Flexor Carpi Radialis muscle?
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What is the insertion of the Flexor Digitorum Superficialis muscle?
What is the insertion of the Flexor Digitorum Superficialis muscle?
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What is the origin of the Abductor Pollicis Longus?
What is the origin of the Abductor Pollicis Longus?
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What is the action of the Extensor Carpi Ulnaris?
What is the action of the Extensor Carpi Ulnaris?
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What is the action of the Flexor Pollicis Longus muscle?
What is the action of the Flexor Pollicis Longus muscle?
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What is the origin of the Pronator Quadratus muscle?
What is the origin of the Pronator Quadratus muscle?
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What is the insertion of the Extensor Digiti Minimi?
What is the insertion of the Extensor Digiti Minimi?
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What is the insertion of the Abductor Pollicis Brevis muscle?
What is the insertion of the Abductor Pollicis Brevis muscle?
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What is the action of the Extensor Digitorum?
What is the action of the Extensor Digitorum?
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What is the origin of the Extensor Carpi Ulnaris?
What is the origin of the Extensor Carpi Ulnaris?
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What is the action of the Flexor Digitorum Profundus muscle?
What is the action of the Flexor Digitorum Profundus muscle?
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What is the action of the Pronator Teres muscle?
What is the action of the Pronator Teres muscle?
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What is the insertion of the Extensor Digitorum?
What is the insertion of the Extensor Digitorum?
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What is the action of the Extensor Pollicis Brevis?
What is the action of the Extensor Pollicis Brevis?
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Which nerve does not innervate the Serratus Anterior?
Which nerve does not innervate the Serratus Anterior?
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What is the action of the Triceps Brachii muscle?
What is the action of the Triceps Brachii muscle?
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What is the origin of the Anconeous muscle?
What is the origin of the Anconeous muscle?
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Which muscle is responsible for wrist extension and radial deviation?
Which muscle is responsible for wrist extension and radial deviation?
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What is the action of the Supinator muscle?
What is the action of the Supinator muscle?
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What is the action of the Brachioradialis muscle?
What is the action of the Brachioradialis muscle?
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Which nerve innervates the skin of the dorsal hand and thumb?
Which nerve innervates the skin of the dorsal hand and thumb?
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What is the origin of the Extensor Carpi Radialis Brevis muscle?
What is the origin of the Extensor Carpi Radialis Brevis muscle?
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What is the path of the Radial nerve?
What is the path of the Radial nerve?
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Study Notes
Brachial Plexus
Definition
- A network of nerve fibers that originate in the spinal cord and branch out to form the nerves of the upper limb
- Extends from the neck to the axilla (armpit)
Formation
- Formed by the ventral rami of spinal nerves C5-T1
- Divided into five roots, three trunks, six divisions, three cords, and five terminal branches
Roots
- Five roots: C5, C6, C7, C8, and T1
- Emerge from the spinal cord and combine to form trunks
Trunks
- Three trunks: superior, middle, and inferior
- Each trunk divides into an anterior and posterior division
Divisions
- Six divisions: three anterior and three posterior
- Divisions from each trunk merge to form cords
Cords
- Three cords: lateral, medial, and posterior
- Cords give rise to the terminal branches
Terminal Branches
- Five terminal branches:
- Musculocutaneous nerve
- Axillary nerve
- Radial nerve
- Median nerve
- Ulnar nerve
- These nerves distribute to the upper limb, controlling motor and sensory functions
Clinical Relevance
- Brachial plexus injuries can result from trauma, tumors, or birth injuries
- Symptoms include weakness, numbness, or paralysis in the upper limb
- Diagnosis involves physical examination, electromyography, and imaging studies
Brachial Plexus
Definition and Location
- A network of nerve fibers originating in the spinal cord and branching out to form the nerves of the upper limb
- Extends from the neck to the axilla (armpit)
Formation and Composition
- Formed by the ventral rami of spinal nerves C5-T1
- Composed of five roots, three trunks, six divisions, three cords, and five terminal branches
Roots
- Five roots emerge from the spinal cord: C5, C6, C7, C8, and T1
- Roots combine to form trunks
Trunks
- Three trunks: superior, middle, and inferior
- Each trunk divides into an anterior and posterior division
Divisions
- Six divisions: three anterior and three posterior
- Divisions from each trunk merge to form cords
Cords
- Three cords: lateral, medial, and posterior
- Cords give rise to the terminal branches
Terminal Branches
- Five terminal branches:
- Musculocutaneous nerve
- Axillary nerve
- Radial nerve
- Median nerve
- Ulnar nerve
- These nerves distribute to the upper limb, controlling motor and sensory functions
Clinical Relevance
- Brachial plexus injuries can result from trauma, tumors, or birth injuries
- Symptoms include weakness, numbness, or paralysis in the upper limb
- Diagnosis involves physical examination, electromyography, and imaging studies
Brachial Plexus
Anatomy
- The brachial plexus is a network of nerves originating from the spinal cord (C5-T1) and extending from the neck to the axilla
- It is divided into five roots, three trunks, six divisions, three cords, and five branches
- The five roots (C5-T1) merge to form three trunks, which then divide into anterior and posterior divisions
- The three cords (lateral, medial, and posterior) are formed from the divisions, and various nerves arise from the cords
Injuries
- Brachial plexus injuries can occur due to trauma, such as motorcycle accidents or falls
- The severity of injuries can range from mild (neurapraxia) to severe (avulsion)
- Injuries can result in weakness or paralysis of the arm, numbness or tingling in the arm or hand, and pain or burning sensations in the arm or hand
Recovery
- Spontaneous recovery is possible in some cases, especially for mild injuries
- Physical therapy and occupational therapy are necessary to maintain range of motion and prevent contractures
- Surgical intervention may be necessary for more severe injuries
- Rehabilitation can be lengthy, taking months to years, and may require ongoing therapy
Nerve Roots
- The C5-C6 roots are primarily responsible for motor function, such as shoulder abduction and elbow flexion
- The C7 root has mixed motor and sensory function, including elbow extension and wrist flexion
- The C8-T1 roots are primarily responsible for sensory function, including hand sensation
Surgical Repair
- Surgical repair is indicated for severe injuries, such as avulsion or rupture
- The goals of surgical repair are to restore motor and sensory function and alleviate pain
- Techniques used in surgical repair include nerve grafting or transfer, nerve repair or reconstruction, and tendon or muscle transfer
- Surgical outcomes vary, and recovery can be lengthy and challenging
Muscles and Nerves of the Forearm and Arm
Forearm Muscles
- Pronator Teres:
- Origin: Medial epicondyle (superficial head), coronoid process (deep head)
- Insertion: Mid-lateral radius below anterior oblique line
- Action: Pronation of radius and ulna, stabilization of elbow
- Flexor Carpi Radialis:
- Origin: Medial epicondyle
- Insertion: Base of 2nd and 3rd metacarpal
- Action: Flexion of wrist, radial deviation, stabilization of elbow
- Palmaris Longus:
- Origin: Medial epicondyle
- Insertion: Palmar aponeurosis
- Action: Flexion of wrist, stabilization of elbow
- Flexor Digitorum Superficialis:
- Origin: Medial epicondyle, coronoid process, anterior oblique line of radius
- Insertion: Sides of middle phalanx of digits 2-5
- Action: Flexion of proximal interphalangeal and metacarpophalangeal joints, wrist flexion, stabilization of elbow
- Flexor Digitorum Profundus:
- Origin: Proximal ¾ of medial and anterior ulna, adjacent interosseous membrane
- Insertion: Bases of distal phalanges of digits 2-5
- Action: Flexion of distal interphalangeal and metacarpophalangeal joints, wrist flexion
- Flexor Pollicis Longus:
- Origin: Middle ½ of anterior radius, adjacent interosseous membrane
- Insertion: Base of distal phalanx of thumb
- Action: Flexion of interphalangeal and metacarpophalangeal joints, wrist flexion, stabilization of elbow
- Pronator Quadratus:
- Origin: Distal ¼ of ulna
- Insertion: Distal ¼ of radius
- Action: Pronation of radius and ulna
Long Thoracic Nerve
- Innervates Serratus Anterior:
- Origin: Upper 8 ribs at mid-axillary line
- Insertion: Deep medial border of scapula
- Action: Protraction of scapula, upward rotation, stabilization of scapula
Dorsal Scapular Nerve
- Innervates skin over deltoid region
Radial Nerve
- Passes through radial groove, sends off 6 branches
- Innervates:
- Triceps Brachii (3 branches)
- Origin: Long head (infraglenoid tubercle and capsule), lateral head (posterior humerus lateral to radial groove), medial head (posterior humerus medial to radial groove)
- Insertion: Olecranon process
- Action: Extension of elbow, adduction of humerus
- Anconeous:
- Origin: Lateral epicondyle
- Insertion: Lateral olecranon and proximal shaft of ulna
- Action: Stabilization of elbow
- Skin of posterior arm and forearm
- Triceps Brachii (3 branches)
- Passes through radial groove, intermuscular septum between lateral head of triceps and brachialis, and innervates:
- Brachioradialis:
- Origin: Lateral supracondylar ridge
- Insertion: Styloid process of radius
- Action: Flexion of elbow
- Extensor Carpi Radialis Longus:
- Origin: Lateral supracondylar ridge
- Insertion: Base of 2nd metacarpal
- Action: Extension of wrist, radial deviation, stabilization of elbow
- Brachioradialis:
- Ends by dividing into superficial and deep radial nerves
- Superficial radial nerve: Innervates skin of dorsal hand and thumb
- Deep radial nerve: Innervates:
- Supinator:
- Origin: Posterior ulna below radial notch
- Insertion: Posterior, anterior, and lateral proximal 1/3 of radius
- Action: Supination of radius and ulna
- Extensor Carp Radialis Brevis:
- Origin: Lateral epicondyle
- Insertion: Base of 3rd metacarpal
- Action: Extension of wrist, radial deviation, stabilization of elbow
- Supinator:
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Description
Learn about the formation and structure of the brachial plexus, a network of nerve fibers that originate in the spinal cord and branch out to form the nerves of the upper limb.
