Podcast
Questions and Answers
Which spinal roots primarily contribute to the formation of the brachial plexus?
Which spinal roots primarily contribute to the formation of the brachial plexus?
The upper trunk of the brachial plexus is formed by nerve roots C5 and C7.
The upper trunk of the brachial plexus is formed by nerve roots C5 and C7.
False
What mnemonic helps to remember the components of the brachial plexus?
What mnemonic helps to remember the components of the brachial plexus?
Mar mu
The _________ Nerve supplies muscles in the anterior forearm and some hand muscles.
The _________ Nerve supplies muscles in the anterior forearm and some hand muscles.
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Match the nerves to their corresponding primary muscles or functions:
Match the nerves to their corresponding primary muscles or functions:
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What forms the posterior cord of the brachial plexus?
What forms the posterior cord of the brachial plexus?
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The long thoracic nerve helps in scapular elevation.
The long thoracic nerve helps in scapular elevation.
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Which minor nerve supplies the subclavius muscle?
Which minor nerve supplies the subclavius muscle?
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Which muscle is primarily responsible for extending the elbow joint?
Which muscle is primarily responsible for extending the elbow joint?
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The lower trunk of the brachial plexus is formed by nerve roots _________ and T1.
The lower trunk of the brachial plexus is formed by nerve roots _________ and T1.
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What is the function of the dorsal scapular nerve?
What is the function of the dorsal scapular nerve?
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The pectoralis major is responsible for adducting the shoulder.
The pectoralis major is responsible for adducting the shoulder.
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Name the nerve responsible for supplying the muscle that flexes and adducts the shoulder.
Name the nerve responsible for supplying the muscle that flexes and adducts the shoulder.
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The __________ extends the fingers.
The __________ extends the fingers.
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Match the following nerves with their primary functions:
Match the following nerves with their primary functions:
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What is the main function of the teres major muscle?
What is the main function of the teres major muscle?
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The ulnar nerve innervates the thenar muscles.
The ulnar nerve innervates the thenar muscles.
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What syndrome can occur due to compression of the median nerve?
What syndrome can occur due to compression of the median nerve?
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The primary muscles in the anatomical snuffbox are the abductor pollicis longus, extensor pollicis brevis, and __________.
The primary muscles in the anatomical snuffbox are the abductor pollicis longus, extensor pollicis brevis, and __________.
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Which nerve provides cutaneous sensation to the dorsal hand?
Which nerve provides cutaneous sensation to the dorsal hand?
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Which nerve is primarily responsible for motor function in the biceps brachii?
Which nerve is primarily responsible for motor function in the biceps brachii?
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The lateral cord of the brachial plexus is formed by the anterior division of the lower trunk.
The lateral cord of the brachial plexus is formed by the anterior division of the lower trunk.
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What muscles does the axillary nerve supply?
What muscles does the axillary nerve supply?
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The posterior cord of the brachial plexus is formed from the __________ divisions of the trunks.
The posterior cord of the brachial plexus is formed from the __________ divisions of the trunks.
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Match the following minor nerves with their functions:
Match the following minor nerves with their functions:
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The musculocutaneous nerve supplies the __________.
The musculocutaneous nerve supplies the __________.
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The median nerve mainly supplies muscles in the posterior forearm.
The median nerve mainly supplies muscles in the posterior forearm.
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What is the function of the long thoracic nerve?
What is the function of the long thoracic nerve?
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The __________ nerve supplies skin over the deltoid muscle.
The __________ nerve supplies skin over the deltoid muscle.
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Which of the following trunks is formed by the spinal root C7?
Which of the following trunks is formed by the spinal root C7?
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What is the primary function of the triceps brachii?
What is the primary function of the triceps brachii?
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The musculocutaneous nerve innervates the skin over the deltoid.
The musculocutaneous nerve innervates the skin over the deltoid.
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Which nerve runs through the carpal tunnel and is prone to compression?
Which nerve runs through the carpal tunnel and is prone to compression?
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The __________ muscles are responsible for thumb adduction and are innervated by the ulnar nerve.
The __________ muscles are responsible for thumb adduction and are innervated by the ulnar nerve.
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Match each muscle to its corresponding function:
Match each muscle to its corresponding function:
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Which muscle specifically extends the little finger?
Which muscle specifically extends the little finger?
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The radial nerve primarily supplies motor branches to flexor muscles in the forearm.
The radial nerve primarily supplies motor branches to flexor muscles in the forearm.
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What is the primary action of the extensor carpi radialis longus?
What is the primary action of the extensor carpi radialis longus?
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The __________ nerve provides sensory innervation to the dorsal surface of the hand.
The __________ nerve provides sensory innervation to the dorsal surface of the hand.
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Which muscle assists the triceps brachii in extending the elbow?
Which muscle assists the triceps brachii in extending the elbow?
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Which muscle is responsible for flexing and adducting the shoulder?
Which muscle is responsible for flexing and adducting the shoulder?
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The medial nerve runs through the carpal tunnel and can cause carpal tunnel syndrome upon compression.
The medial nerve runs through the carpal tunnel and can cause carpal tunnel syndrome upon compression.
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What is the primary action of the triceps brachii?
What is the primary action of the triceps brachii?
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The long thoracic nerve assists in __________ elevation.
The long thoracic nerve assists in __________ elevation.
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Match the following muscles with their corresponding functions:
Match the following muscles with their corresponding functions:
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Which nerve supplies the extensor muscles in the forearm?
Which nerve supplies the extensor muscles in the forearm?
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The ulnar nerve provides sensory innervation primarily to the lateral third of the hand.
The ulnar nerve provides sensory innervation primarily to the lateral third of the hand.
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Name the primary muscle responsible for protracting the scapula.
Name the primary muscle responsible for protracting the scapula.
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The __________ muscles innervated by the ulnar nerve contribute to pinky dexterity.
The __________ muscles innervated by the ulnar nerve contribute to pinky dexterity.
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Match each nerve to its primary sensory function:
Match each nerve to its primary sensory function:
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Which nerve primarily supplies the deltoid muscle?
Which nerve primarily supplies the deltoid muscle?
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The brachial plexus consists of five trunks.
The brachial plexus consists of five trunks.
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Name the nerve responsible for innervating the rhomboids.
Name the nerve responsible for innervating the rhomboids.
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The upper trunk of the brachial plexus is formed by the spinal roots __________ and C6.
The upper trunk of the brachial plexus is formed by the spinal roots __________ and C6.
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Match the following nerves with their primary functions:
Match the following nerves with their primary functions:
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Which nerve aids in scapular protraction?
Which nerve aids in scapular protraction?
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The posterior cord of the brachial plexus is formed exclusively from the anterior divisions of the trunks.
The posterior cord of the brachial plexus is formed exclusively from the anterior divisions of the trunks.
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What is the primary function of the teres minor muscle?
What is the primary function of the teres minor muscle?
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The __________ nerve supplies the skin of the lateral forearm.
The __________ nerve supplies the skin of the lateral forearm.
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Match the nerves with their respective muscles:
Match the nerves with their respective muscles:
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Which muscle group is responsible for extending the elbow joint?
Which muscle group is responsible for extending the elbow joint?
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The radial nerve supplies motor branches to the extensor muscles in the forearm.
The radial nerve supplies motor branches to the extensor muscles in the forearm.
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What is the primary function of the pectoralis minor muscle?
What is the primary function of the pectoralis minor muscle?
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The _________ nerve innervates the hypothenar muscles.
The _________ nerve innervates the hypothenar muscles.
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Match the following muscles with their actions:
Match the following muscles with their actions:
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Which nerve is primarily responsible for sensation in the lateral forearm?
Which nerve is primarily responsible for sensation in the lateral forearm?
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The axillary nerve supplies the skin over the abdomen.
The axillary nerve supplies the skin over the abdomen.
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Which muscle specifically targets the index finger for extension?
Which muscle specifically targets the index finger for extension?
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The anatomical snuffbox contains the _________, which are key for thumb function.
The anatomical snuffbox contains the _________, which are key for thumb function.
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Match the following nerves with their sensory functions:
Match the following nerves with their sensory functions:
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Which nerve is responsible for supplying muscles in the anterior forearm?
Which nerve is responsible for supplying muscles in the anterior forearm?
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The lateral cord of the brachial plexus is formed solely by the anterior division of the upper trunk.
The lateral cord of the brachial plexus is formed solely by the anterior division of the upper trunk.
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What is the main function of the dorsal scapular nerve?
What is the main function of the dorsal scapular nerve?
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The __________ nerve supplies the deltoid muscle.
The __________ nerve supplies the deltoid muscle.
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Match the following nerves to their primary function:
Match the following nerves to their primary function:
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What forms the medial cord of the brachial plexus?
What forms the medial cord of the brachial plexus?
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The suprascapular nerve supplies muscles responsible for shoulder movements.
The suprascapular nerve supplies muscles responsible for shoulder movements.
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Which nerve provides sensory innervation to the skin over the lateral forearm?
Which nerve provides sensory innervation to the skin over the lateral forearm?
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The __________ nerve is known to be prone to compression in the carpal tunnel.
The __________ nerve is known to be prone to compression in the carpal tunnel.
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Which of the following trunks is formed by the spinal roots C5 and C6?
Which of the following trunks is formed by the spinal roots C5 and C6?
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Which nerve is responsible for supplying the deltoid muscle?
Which nerve is responsible for supplying the deltoid muscle?
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The medial cord is formed by the anterior divisions of the upper and lower trunks.
The medial cord is formed by the anterior divisions of the upper and lower trunks.
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Name one function of the long thoracic nerve.
Name one function of the long thoracic nerve.
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The _________ nerve provides cutaneous sensation to the lateral forearm.
The _________ nerve provides cutaneous sensation to the lateral forearm.
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Match the following nerves with their primary functions:
Match the following nerves with their primary functions:
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What is the main function of the musculocutaneous nerve?
What is the main function of the musculocutaneous nerve?
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C5 and C6 nerve roots combine to form the lower trunk of the brachial plexus.
C5 and C6 nerve roots combine to form the lower trunk of the brachial plexus.
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What muscle does the axillary nerve innervate?
What muscle does the axillary nerve innervate?
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The _________ nerve aids in scapular retraction.
The _________ nerve aids in scapular retraction.
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Match the trunks with their corresponding spinal roots:
Match the trunks with their corresponding spinal roots:
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What is the primary action of the latissimus dorsi muscle?
What is the primary action of the latissimus dorsi muscle?
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The radial nerve supplies motor branches to all extensor muscles in the forearm.
The radial nerve supplies motor branches to all extensor muscles in the forearm.
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What muscle assists in flexing and adducting the shoulder?
What muscle assists in flexing and adducting the shoulder?
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The __________ nerve provides cutaneous sensation to the medial third of the hand.
The __________ nerve provides cutaneous sensation to the medial third of the hand.
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Match the following muscles with their primary actions:
Match the following muscles with their primary actions:
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Which of the following muscles is NOT associated with thumb movement?
Which of the following muscles is NOT associated with thumb movement?
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The median nerve is responsible for innervating most of the forearm flexors.
The median nerve is responsible for innervating most of the forearm flexors.
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Identify the nerve that runs through the carpal tunnel.
Identify the nerve that runs through the carpal tunnel.
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The __________ muscles are innervated by the ulnar nerve and are crucial for pinky dexterity.
The __________ muscles are innervated by the ulnar nerve and are crucial for pinky dexterity.
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Match the nerves to their corresponding sensory regions:
Match the nerves to their corresponding sensory regions:
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Study Notes
Brachial Plexus Overview
- The brachial plexus originates primarily from spinal roots C5 to T1.
- C5 and C6 nerve roots combine to form the upper trunk; C7 forms the middle trunk; C8 and T1 join to form the lower trunk.
Key Mnemonics
- "Mar mu" represents:
- R: Root
- T: Trunk
- D: Division
- C: Cord
- B: Branch
Structure of the Brachial Plexus
-
Trunks:
- Upper Trunk: Formed by C5 and C6.
- Middle Trunk: Formed by C7.
- Lower Trunk: Formed by C8 and T1.
- Each trunk divides into anterior and posterior divisions.
Cords Formation
- Posterior Cord: Formed from all posterior divisions of the trunks.
- Lateral Cord: Formed from the anterior divisions of the upper and middle trunks.
- Medial Cord: Formed from the anterior division of the lower trunk.
Major Nerves from Brachial Plexus
-
Musculocutaneous Nerve:
- Supplies lateral forearm (cutaneous) and muscles: coracobrachialis, brachialis, biceps brachii (motor).
-
Axillary Nerve:
- Supplies skin over deltoid (cutaneous) and muscles: deltoid and teres minor (motor).
-
Radial Nerve:
- Supplies a large area of the arm and dorsal surface of the hand (cutaneous), numerous muscles (motor) including those for elbow extension and wrist/hand movement.
-
Median Nerve:
- Supplies muscles in the anterior forearm and some hand muscles.
-
Ulnar Nerve:
- Supplies muscles in the forearm and hand, particularly on the medial side.
Minor Nerves and Their Functions
- Dorsal Scapular Nerve: Supplies rhomboids and levator scapulae, involved in scapular retraction and elevation.
- Long Thoracic Nerve: Supplies serratus anterior, aiding in scapular protraction.
- Suprascapular Nerve: Supplies supraspinatus and infraspinatus for shoulder movements.
- Nerve to Subclavius: Supplies subclavius muscle to depress the clavicle.
- Lateral Pectoral Nerve: Supplies pectoralis major.
- Medial Pectoral Nerve: Supplies pectoralis major and minor.
Important Muscle Functions
-
Pectoralis Major:
- Flexes, adducts, and medially rotates the shoulder.
-
Pectoralis Minor:
- Protracts the scapula.
-
Latissimus Dorsi:
- Extends, adducts, and medially rotates the shoulder.
-
Teres Major:
- Similar function as latissimus dorsi.
-
Coracobrachialis:
- Flexes and adducts the shoulder.
Cutaneous Innervations Summary
- Lateral forearm: Musculocutaneous nerve.
- Skin over deltoid: Axillary nerve.
- Dorsal hand: Radial nerve (distal portion).
- Anterior forearm and hand: Median and Ulnar nerves cover specific regions.
Summary of Functional Dynamics
- The brachial plexus is essential for upper limb motor and sensory innervation, affecting shoulder and arm movements.
- Knowledge of its structure and branches is crucial for understanding upper limb anatomy and function.### Muscles of the Posterior Arm and Forearm
- Triceps brachii consists of three heads and primarily extends the elbow joint.
- Anconeus assists the triceps brachii in extending the elbow.
- Brachioradialis, located in the forearm, flexes the elbow.
- Extensor carpi radialis longus and brevis extend the wrist and are positioned adjacent to the brachioradialis.
- Extensor digitorum extends the fingers, while extensor indicis specifically targets the index finger.
- Extensor digiti minimi extends the little finger, enhancing dexterity.
- Extensor carpi ulnaris aids in wrist extension.
- Anatomical snuffbox region contains abductor pollicis longus, extensor pollicis brevis, and extensor pollicis longus, key muscles for thumb function.
- Supinator, located beneath brachioradialis, is crucial for supination of the palm.
Nerve Supplies and Branches
- Radial nerve supplies motor branches to nearly all extensor muscles in the forearm.
- Median nerve has cutaneous branches, providing sensation to the ventral and lateral palm and digits two and three.
- Median nerve runs through the carpal tunnel, and compression can lead to carpal tunnel syndrome.
- Motor branches of the median nerve innervate multiple forearm flexors including pronator teres, quadratus, palmaris longus, flexor carpi radialis, flexor digitorum superficialis, and flexor digitorum profundus.
- Supplies second and third lumbricals, enabling complex hand movements.
- Thenar muscles innervated by median nerve include opponens pollicis, flexor pollicis brevis, and abductor pollicis brevis.
Ulnar Nerve Functionality
- Ulnar nerve provides cutaneous branches supplying the ventral and dorsal surfaces of the medial third of the hand.
- Motor branches of the ulnar nerve supply deeper muscles, including flexor carpi ulnaris and ulnar half of flexor digitorum profundus.
- Hypothenar muscles innervated by ulnar nerve consist of opponens digiti minimi, flexor digiti minimi, and abductor digiti minimi, contributing to pinky dexterity.
- Adductor pollicis is also supplied by the ulnar nerve, facilitating thumb adduction.
Brachial Plexus Overview
- Originates from spinal roots C5 to T1.
- Composed of upper trunk (C5-C6), middle trunk (C7), and lower trunk (C8-T1).
Key Mnemonics
- "Mar mu" helps remember the order:
- R: Root
- T: Trunk
- D: Division
- C: Cord
- B: Branch
Structure of the Brachial Plexus
-
Trunks:
- Upper trunk is C5 and C6.
- Middle trunk is C7.
- Lower trunk is C8 and T1.
- Each trunk branches into anterior and posterior divisions.
Cords Formation
- Posterior Cord: Formed by posterior divisions of all trunks.
- Lateral Cord: Anterior divisions of upper and middle trunks.
- Medial Cord: Anterior division of lower trunk.
Major Nerves from Brachial Plexus
-
Musculocutaneous Nerve:
- Innervates lateral forearm and flexor muscles (coracobrachialis, brachialis, biceps brachii).
-
Axillary Nerve:
- Supplies deltoid skin and muscles (deltoid, teres minor).
-
Radial Nerve:
- Covers a large area of the arm and dorsal hand; innervates extensors.
-
Median Nerve:
- Innervates forearm flexors and some hand muscles.
-
Ulnar Nerve:
- Supplies forearm and hand muscles, especially on the medial side.
Minor Nerves and Their Functions
- Dorsal Scapular Nerve: Supplies rhomboids and levator scapulae for scapular movements.
- Long Thoracic Nerve: Innervates serratus anterior for scapular protraction.
- Suprascapular Nerve: Supplies supraspinatus and infraspinatus for shoulder movement.
- Nerve to Subclavius: Innervates subclavius muscle, assisting in clavicle depression.
- Lateral and Medial Pectoral Nerves: Supply pectoralis major and minor.
Important Muscle Functions
- Pectoralis Major: Flexes, adducts, medially rotates shoulder.
- Pectoralis Minor: Protracts scapula.
- Latissimus Dorsi & Teres Major: Extend, adduct, medially rotate shoulder.
- Coracobrachialis: Flexes and adducts the shoulder.
Cutaneous Innervations Summary
- Lateral Forearm: Musculocutaneous nerve.
- Deltoid Skin: Axillary nerve.
- Dorsal Hand: Radial nerve (distal).
- Anterior Forearm & Hand: Median and ulnar nerves cover specific areas.
Summary of Functional Dynamics
- Brachial plexus is vital for motor and sensory innervation of the upper limb.
- Understanding structure and branches is essential for grasping upper limb anatomy.
Muscles of the Posterior Arm and Forearm
- Triceps Brachii: Extends elbow joint with three heads.
- Anconeus: Assists in elbow extension.
- Brachioradialis: Flexes elbow in the forearm.
- Extensors (carpi and digitorum): Facilitate wrist and finger movements.
- Anatomical Snuffbox: Contains muscles important for thumb function (abductor pollicis longus, extensor pollicis brevis/longus).
- Supinator: Critical for palm supination, placed beneath brachioradialis.
Nerve Supplies and Branches
- Radial Nerve: Innervates most extensors in the forearm.
- Median Nerve: Provides cutaneous sensation to palm and parts of digits; runs through carpal tunnel, where compression leads to carpal tunnel syndrome.
- Motor Functions of Median Nerve: Innervates flexors and lumbricals for advanced hand movements.
- Thenar Muscles: Innervated by median nerve for thumb movement.
Ulnar Nerve Functionality
- Cutaneous Distribution: Supplies the medial third of the hand, both ventral and dorsal.
- Motor Branches: Innervate deeper forearm muscles and hypothenar muscles for pinky dexterity.
- Adductor Pollicis: Also supplied by ulnar nerve for thumb adduction.
Brachial Plexus Overview
- Originates from spinal roots C5 to T1.
- Composed of upper trunk (C5-C6), middle trunk (C7), and lower trunk (C8-T1).
Key Mnemonics
- "Mar mu" helps remember the order:
- R: Root
- T: Trunk
- D: Division
- C: Cord
- B: Branch
Structure of the Brachial Plexus
-
Trunks:
- Upper trunk is C5 and C6.
- Middle trunk is C7.
- Lower trunk is C8 and T1.
- Each trunk branches into anterior and posterior divisions.
Cords Formation
- Posterior Cord: Formed by posterior divisions of all trunks.
- Lateral Cord: Anterior divisions of upper and middle trunks.
- Medial Cord: Anterior division of lower trunk.
Major Nerves from Brachial Plexus
-
Musculocutaneous Nerve:
- Innervates lateral forearm and flexor muscles (coracobrachialis, brachialis, biceps brachii).
-
Axillary Nerve:
- Supplies deltoid skin and muscles (deltoid, teres minor).
-
Radial Nerve:
- Covers a large area of the arm and dorsal hand; innervates extensors.
-
Median Nerve:
- Innervates forearm flexors and some hand muscles.
-
Ulnar Nerve:
- Supplies forearm and hand muscles, especially on the medial side.
Minor Nerves and Their Functions
- Dorsal Scapular Nerve: Supplies rhomboids and levator scapulae for scapular movements.
- Long Thoracic Nerve: Innervates serratus anterior for scapular protraction.
- Suprascapular Nerve: Supplies supraspinatus and infraspinatus for shoulder movement.
- Nerve to Subclavius: Innervates subclavius muscle, assisting in clavicle depression.
- Lateral and Medial Pectoral Nerves: Supply pectoralis major and minor.
Important Muscle Functions
- Pectoralis Major: Flexes, adducts, medially rotates shoulder.
- Pectoralis Minor: Protracts scapula.
- Latissimus Dorsi & Teres Major: Extend, adduct, medially rotate shoulder.
- Coracobrachialis: Flexes and adducts the shoulder.
Cutaneous Innervations Summary
- Lateral Forearm: Musculocutaneous nerve.
- Deltoid Skin: Axillary nerve.
- Dorsal Hand: Radial nerve (distal).
- Anterior Forearm & Hand: Median and ulnar nerves cover specific areas.
Summary of Functional Dynamics
- Brachial plexus is vital for motor and sensory innervation of the upper limb.
- Understanding structure and branches is essential for grasping upper limb anatomy.
Muscles of the Posterior Arm and Forearm
- Triceps Brachii: Extends elbow joint with three heads.
- Anconeus: Assists in elbow extension.
- Brachioradialis: Flexes elbow in the forearm.
- Extensors (carpi and digitorum): Facilitate wrist and finger movements.
- Anatomical Snuffbox: Contains muscles important for thumb function (abductor pollicis longus, extensor pollicis brevis/longus).
- Supinator: Critical for palm supination, placed beneath brachioradialis.
Nerve Supplies and Branches
- Radial Nerve: Innervates most extensors in the forearm.
- Median Nerve: Provides cutaneous sensation to palm and parts of digits; runs through carpal tunnel, where compression leads to carpal tunnel syndrome.
- Motor Functions of Median Nerve: Innervates flexors and lumbricals for advanced hand movements.
- Thenar Muscles: Innervated by median nerve for thumb movement.
Ulnar Nerve Functionality
- Cutaneous Distribution: Supplies the medial third of the hand, both ventral and dorsal.
- Motor Branches: Innervate deeper forearm muscles and hypothenar muscles for pinky dexterity.
- Adductor Pollicis: Also supplied by ulnar nerve for thumb adduction.
Brachial Plexus Overview
- Originates from spinal roots C5 to T1.
- Composed of upper trunk (C5-C6), middle trunk (C7), and lower trunk (C8-T1).
Key Mnemonics
- "Mar mu" helps remember the order:
- R: Root
- T: Trunk
- D: Division
- C: Cord
- B: Branch
Structure of the Brachial Plexus
-
Trunks:
- Upper trunk is C5 and C6.
- Middle trunk is C7.
- Lower trunk is C8 and T1.
- Each trunk branches into anterior and posterior divisions.
Cords Formation
- Posterior Cord: Formed by posterior divisions of all trunks.
- Lateral Cord: Anterior divisions of upper and middle trunks.
- Medial Cord: Anterior division of lower trunk.
Major Nerves from Brachial Plexus
-
Musculocutaneous Nerve:
- Innervates lateral forearm and flexor muscles (coracobrachialis, brachialis, biceps brachii).
-
Axillary Nerve:
- Supplies deltoid skin and muscles (deltoid, teres minor).
-
Radial Nerve:
- Covers a large area of the arm and dorsal hand; innervates extensors.
-
Median Nerve:
- Innervates forearm flexors and some hand muscles.
-
Ulnar Nerve:
- Supplies forearm and hand muscles, especially on the medial side.
Minor Nerves and Their Functions
- Dorsal Scapular Nerve: Supplies rhomboids and levator scapulae for scapular movements.
- Long Thoracic Nerve: Innervates serratus anterior for scapular protraction.
- Suprascapular Nerve: Supplies supraspinatus and infraspinatus for shoulder movement.
- Nerve to Subclavius: Innervates subclavius muscle, assisting in clavicle depression.
- Lateral and Medial Pectoral Nerves: Supply pectoralis major and minor.
Important Muscle Functions
- Pectoralis Major: Flexes, adducts, medially rotates shoulder.
- Pectoralis Minor: Protracts scapula.
- Latissimus Dorsi & Teres Major: Extend, adduct, medially rotate shoulder.
- Coracobrachialis: Flexes and adducts the shoulder.
Cutaneous Innervations Summary
- Lateral Forearm: Musculocutaneous nerve.
- Deltoid Skin: Axillary nerve.
- Dorsal Hand: Radial nerve (distal).
- Anterior Forearm & Hand: Median and ulnar nerves cover specific areas.
Summary of Functional Dynamics
- Brachial plexus is vital for motor and sensory innervation of the upper limb.
- Understanding structure and branches is essential for grasping upper limb anatomy.
Muscles of the Posterior Arm and Forearm
- Triceps Brachii: Extends elbow joint with three heads.
- Anconeus: Assists in elbow extension.
- Brachioradialis: Flexes elbow in the forearm.
- Extensors (carpi and digitorum): Facilitate wrist and finger movements.
- Anatomical Snuffbox: Contains muscles important for thumb function (abductor pollicis longus, extensor pollicis brevis/longus).
- Supinator: Critical for palm supination, placed beneath brachioradialis.
Nerve Supplies and Branches
- Radial Nerve: Innervates most extensors in the forearm.
- Median Nerve: Provides cutaneous sensation to palm and parts of digits; runs through carpal tunnel, where compression leads to carpal tunnel syndrome.
- Motor Functions of Median Nerve: Innervates flexors and lumbricals for advanced hand movements.
- Thenar Muscles: Innervated by median nerve for thumb movement.
Ulnar Nerve Functionality
- Cutaneous Distribution: Supplies the medial third of the hand, both ventral and dorsal.
- Motor Branches: Innervate deeper forearm muscles and hypothenar muscles for pinky dexterity.
- Adductor Pollicis: Also supplied by ulnar nerve for thumb adduction.
Brachial Plexus Overview
- Originates from spinal roots C5 to T1.
- Composed of upper trunk (C5-C6), middle trunk (C7), and lower trunk (C8-T1).
Key Mnemonics
- "Mar mu" helps remember the order:
- R: Root
- T: Trunk
- D: Division
- C: Cord
- B: Branch
Structure of the Brachial Plexus
-
Trunks:
- Upper trunk is C5 and C6.
- Middle trunk is C7.
- Lower trunk is C8 and T1.
- Each trunk branches into anterior and posterior divisions.
Cords Formation
- Posterior Cord: Formed by posterior divisions of all trunks.
- Lateral Cord: Anterior divisions of upper and middle trunks.
- Medial Cord: Anterior division of lower trunk.
Major Nerves from Brachial Plexus
-
Musculocutaneous Nerve:
- Innervates lateral forearm and flexor muscles (coracobrachialis, brachialis, biceps brachii).
-
Axillary Nerve:
- Supplies deltoid skin and muscles (deltoid, teres minor).
-
Radial Nerve:
- Covers a large area of the arm and dorsal hand; innervates extensors.
-
Median Nerve:
- Innervates forearm flexors and some hand muscles.
-
Ulnar Nerve:
- Supplies forearm and hand muscles, especially on the medial side.
Minor Nerves and Their Functions
- Dorsal Scapular Nerve: Supplies rhomboids and levator scapulae for scapular movements.
- Long Thoracic Nerve: Innervates serratus anterior for scapular protraction.
- Suprascapular Nerve: Supplies supraspinatus and infraspinatus for shoulder movement.
- Nerve to Subclavius: Innervates subclavius muscle, assisting in clavicle depression.
- Lateral and Medial Pectoral Nerves: Supply pectoralis major and minor.
Important Muscle Functions
- Pectoralis Major: Flexes, adducts, medially rotates shoulder.
- Pectoralis Minor: Protracts scapula.
- Latissimus Dorsi & Teres Major: Extend, adduct, medially rotate shoulder.
- Coracobrachialis: Flexes and adducts the shoulder.
Cutaneous Innervations Summary
- Lateral Forearm: Musculocutaneous nerve.
- Deltoid Skin: Axillary nerve.
- Dorsal Hand: Radial nerve (distal).
- Anterior Forearm & Hand: Median and ulnar nerves cover specific areas.
Summary of Functional Dynamics
- Brachial plexus is vital for motor and sensory innervation of the upper limb.
- Understanding structure and branches is essential for grasping upper limb anatomy.
Muscles of the Posterior Arm and Forearm
- Triceps Brachii: Extends elbow joint with three heads.
- Anconeus: Assists in elbow extension.
- Brachioradialis: Flexes elbow in the forearm.
- Extensors (carpi and digitorum): Facilitate wrist and finger movements.
- Anatomical Snuffbox: Contains muscles important for thumb function (abductor pollicis longus, extensor pollicis brevis/longus).
- Supinator: Critical for palm supination, placed beneath brachioradialis.
Nerve Supplies and Branches
- Radial Nerve: Innervates most extensors in the forearm.
- Median Nerve: Provides cutaneous sensation to palm and parts of digits; runs through carpal tunnel, where compression leads to carpal tunnel syndrome.
- Motor Functions of Median Nerve: Innervates flexors and lumbricals for advanced hand movements.
- Thenar Muscles: Innervated by median nerve for thumb movement.
Ulnar Nerve Functionality
- Cutaneous Distribution: Supplies the medial third of the hand, both ventral and dorsal.
- Motor Branches: Innervate deeper forearm muscles and hypothenar muscles for pinky dexterity.
- Adductor Pollicis: Also supplied by ulnar nerve for thumb adduction.
Brachial Plexus Overview
- Originates from spinal roots C5 to T1.
- Composed of upper trunk (C5-C6), middle trunk (C7), and lower trunk (C8-T1).
Key Mnemonics
- "Mar mu" helps remember the order:
- R: Root
- T: Trunk
- D: Division
- C: Cord
- B: Branch
Structure of the Brachial Plexus
-
Trunks:
- Upper trunk is C5 and C6.
- Middle trunk is C7.
- Lower trunk is C8 and T1.
- Each trunk branches into anterior and posterior divisions.
Cords Formation
- Posterior Cord: Formed by posterior divisions of all trunks.
- Lateral Cord: Anterior divisions of upper and middle trunks.
- Medial Cord: Anterior division of lower trunk.
Major Nerves from Brachial Plexus
-
Musculocutaneous Nerve:
- Innervates lateral forearm and flexor muscles (coracobrachialis, brachialis, biceps brachii).
-
Axillary Nerve:
- Supplies deltoid skin and muscles (deltoid, teres minor).
-
Radial Nerve:
- Covers a large area of the arm and dorsal hand; innervates extensors.
-
Median Nerve:
- Innervates forearm flexors and some hand muscles.
-
Ulnar Nerve:
- Supplies forearm and hand muscles, especially on the medial side.
Minor Nerves and Their Functions
- Dorsal Scapular Nerve: Supplies rhomboids and levator scapulae for scapular movements.
- Long Thoracic Nerve: Innervates serratus anterior for scapular protraction.
- Suprascapular Nerve: Supplies supraspinatus and infraspinatus for shoulder movement.
- Nerve to Subclavius: Innervates subclavius muscle, assisting in clavicle depression.
- Lateral and Medial Pectoral Nerves: Supply pectoralis major and minor.
Important Muscle Functions
- Pectoralis Major: Flexes, adducts, medially rotates shoulder.
- Pectoralis Minor: Protracts scapula.
- Latissimus Dorsi & Teres Major: Extend, adduct, medially rotate shoulder.
- Coracobrachialis: Flexes and adducts the shoulder.
Cutaneous Innervations Summary
- Lateral Forearm: Musculocutaneous nerve.
- Deltoid Skin: Axillary nerve.
- Dorsal Hand: Radial nerve (distal).
- Anterior Forearm & Hand: Median and ulnar nerves cover specific areas.
Summary of Functional Dynamics
- Brachial plexus is vital for motor and sensory innervation of the upper limb.
- Understanding structure and branches is essential for grasping upper limb anatomy.
Muscles of the Posterior Arm and Forearm
- Triceps Brachii: Extends elbow joint with three heads.
- Anconeus: Assists in elbow extension.
- Brachioradialis: Flexes elbow in the forearm.
- Extensors (carpi and digitorum): Facilitate wrist and finger movements.
- Anatomical Snuffbox: Contains muscles important for thumb function (abductor pollicis longus, extensor pollicis brevis/longus).
- Supinator: Critical for palm supination, placed beneath brachioradialis.
Nerve Supplies and Branches
- Radial Nerve: Innervates most extensors in the forearm.
- Median Nerve: Provides cutaneous sensation to palm and parts of digits; runs through carpal tunnel, where compression leads to carpal tunnel syndrome.
- Motor Functions of Median Nerve: Innervates flexors and lumbricals for advanced hand movements.
- Thenar Muscles: Innervated by median nerve for thumb movement.
Ulnar Nerve Functionality
- Cutaneous Distribution: Supplies the medial third of the hand, both ventral and dorsal.
- Motor Branches: Innervate deeper forearm muscles and hypothenar muscles for pinky dexterity.
- Adductor Pollicis: Also supplied by ulnar nerve for thumb adduction.
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Description
This quiz covers the anatomy and structure of the brachial plexus, detailing its origins, trunks, and major nerves. Learn key mnemonics to help remember the divisions and cords formed from the brachial plexus. Test your knowledge on the critical components of this important neural network.
