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Questions and Answers
What action is performed by the short head of the biceps brachii at the shoulder joint?
What action is performed by the short head of the biceps brachii at the shoulder joint?
Which statement about the brachialis muscle is correct?
Which statement about the brachialis muscle is correct?
Which nerve primarily supplies the triceps brachii muscle?
Which nerve primarily supplies the triceps brachii muscle?
What is the role of the long head of the biceps brachii during shoulder movements?
What is the role of the long head of the biceps brachii during shoulder movements?
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Which nerve is responsible for sensory supply to the lateral surface of the forearm?
Which nerve is responsible for sensory supply to the lateral surface of the forearm?
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Which of the following actions does the triceps brachii perform?
Which of the following actions does the triceps brachii perform?
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Which origins are associated with the medial head of the triceps brachii?
Which origins are associated with the medial head of the triceps brachii?
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What is the main nerve supply for the anterior compartment of the arm?
What is the main nerve supply for the anterior compartment of the arm?
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What is the origin of the axillary nerve?
What is the origin of the axillary nerve?
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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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Which nerve supplies the muscles in the anterior compartment of the arm?
Which nerve supplies the muscles in the anterior compartment of the arm?
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What is a potential effect of an axillary nerve injury?
What is a potential effect of an axillary nerve injury?
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Where does the biceps brachii insert?
Where does the biceps brachii insert?
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Which artery supplies the posterior compartment of the arm?
Which artery supplies the posterior compartment of the arm?
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Which muscle assists in both flexion and adduction of the shoulder joint?
Which muscle assists in both flexion and adduction of the shoulder joint?
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What is the function of the bicipital aponeurosis?
What is the function of the bicipital aponeurosis?
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What is the largest branch of the brachial artery?
What is the largest branch of the brachial artery?
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What is the primary function of the median nerve in the arm?
What is the primary function of the median nerve in the arm?
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Which muscle separates the brachial artery from the humerus in the lower part of the arm?
Which muscle separates the brachial artery from the humerus in the lower part of the arm?
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Which nerve enters the posterior compartment of the arm and is accompanied by the superior ulnar collateral artery?
Which nerve enters the posterior compartment of the arm and is accompanied by the superior ulnar collateral artery?
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At which anatomical position does the radial nerve pierce the lateral intermuscular septum?
At which anatomical position does the radial nerve pierce the lateral intermuscular septum?
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What is the posterior boundary of the cubital fossa?
What is the posterior boundary of the cubital fossa?
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What is a major characteristic of the ulnar nerve's course in the arm?
What is a major characteristic of the ulnar nerve's course in the arm?
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Which nerve passes medial to the brachial artery within the cubital fossa?
Which nerve passes medial to the brachial artery within the cubital fossa?
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Which muscle does the radial nerve pass obliquely between to reach the spiral groove?
Which muscle does the radial nerve pass obliquely between to reach the spiral groove?
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What forms the apex of the cubital fossa?
What forms the apex of the cubital fossa?
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The brachial artery is a continuation of which artery at the lower border of the teres major?
The brachial artery is a continuation of which artery at the lower border of the teres major?
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What is the primary anatomical role of the cubital fossa?
What is the primary anatomical role of the cubital fossa?
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Which of the following arteries is a terminal branch of the brachial artery?
Which of the following arteries is a terminal branch of the brachial artery?
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Which nerve provides innervation to the brachialis muscle?
Which nerve provides innervation to the brachialis muscle?
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What is the floor of the cubital fossa made up of?
What is the floor of the cubital fossa made up of?
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What is a notable feature of the radial nerve along its path in the arm?
What is a notable feature of the radial nerve along its path in the arm?
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Study Notes
Axillary Nerve (Circumflex Nerve)
- Originates from the posterior cord of the brachial plexus.
- Root values: C5, 6 nerves.
- Course: Runs with posterior circumflex humeral vessels through the quadrangular space, turning behind the surgical neck of the humerus.
- Branches:
- Articular: Supplies the shoulder joint.
- Muscular: Innervates the deltoid muscle and teres minor.
- Cutaneous: Provides sensory innervation to the upper lateral portion of the arm (lower half of the deltoid).
Axillary Nerve Injury
- Causes: Fracture of the surgical neck of the humerus or shoulder dislocation.
- Effects:
- Paralysis of the deltoid muscle, resulting in loss of abduction (movement away from the body) from 15 to 90 degrees and shoulder flattening.
- Weakening of lateral rotation of the shoulder, due to teres minor involvement.
- Loss of sensation in the upper portion of the lateral side of the arm (lower half of the deltoid).
Compartments of the Arm
- Two major compartments: anterior and posterior, divided by intermuscular septa (medial and lateral).
Anterior Compartment
- Muscles: Coracobrachialis, biceps brachii, and brachialis.
- Nerve supply: Musculocutaneous nerve.
- Action: Flexion of the elbow joint.
Posterior Compartment
- Muscle: Triceps brachii.
- Nerve supply: Radial nerve.
- Action: Extension of the elbow joint.
Coracobrachialis Muscle
- Origin: Tip of the coracoid process of the scapula, along with the short head of the biceps.
- Insertion: Middle of the medial border of the humerus.
- Nerve supply: Musculocutaneous nerve.
- Action: Flexion and adduction of the shoulder joint.
Muscles of the Arm (Biceps Brachii)
- Origins:
- Short head: Tip of the coracoid process.
- Long head: Supraglenoid tubercle.
- Insertion: Radial tuberosity, bicipital aponeurosis to the deep fascia of the forearm.
- Nerve supply: Musculocutaneous nerve.
- Action: Flexion and supination of the forearm, flexion of the shoulder.
Muscles of the Arm (Action)
- Short head: Flexes the shoulder.
- Long head: Stabilizes the head of the humerus during shoulder movements; flexes the elbow.
- Powerful forearm flexor.
- Powerful forearm supinator (when elbow is flexed).
Brachialis Muscle
- Origin: Lower half of the anterior surface of the humerus.
- Insertion: Ulnar tuberosity.
- Nerve supply: Primarily musculocutaneous, with radial nerve supplying the lateral portion (double nerve supply).
- Action: Principle flexor of the elbow joint.
Triceps Brachii Muscle
- Three heads:
- Long head: Infraglenoid tubercle of the scapula.
- Lateral head: Above the radial groove.
- Medial head: Below the radial groove.
- Insertion: Olecranon process of the ulna.
- Nerve supply: Radial nerve.
- Action: Extension of the forearm at the elbow joint
Nerves of the Arm
- Musculocutaneous: Anterior compartment of the arm.
- Radial: Posterior compartment of the arm (no branches in the arm).
- Ulnar: (No branches in the arm).
- Median: (No branches in the arm).
Cubital Fossa
- Triangular-shaped space in front of the elbow.
- Boundaries:
- Lateral: Brachioradialis.
- Medial: Pronator teres.
- Apex: Directed downwards.
- Base: Line connecting the medial and lateral epicondyles of the humerus.
- Floor: Brachialis (medially), Supinator (laterally).
- Roof: Skin, superficial fascia containing cephalic, basilic, and median cubital veins, medial and lateral cutaneous nerves of the forearm, bicipital aponeurosis.
Contents of Cubital Fossa
- Median Nerve.
- Brachial Artery (divides into radial and ulnar arteries).
- Biceps brachii tendon.
- Deep branch of radial nerve.
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Description
Test your knowledge about the axillary nerve, its anatomy, potential injuries, and their effects. This quiz covers the origins, course, branches, and clinical implications of axillary nerve damage. Perfect for students studying human anatomy and neuroanatomy.
