30 Questions
Which nerve is the terminal branch of the lateral cord of the brachial plexus?
Musculocutaneous nerve
What is the main function of the triceps brachii muscle?
Extension of the forearm
Which of the following is a branch of the musculocutaneous nerve?
Lateral cutaneous nerve of forearm
What is the location of the radial nerve in the arm?
Posterior to the axillary artery
Which structure does the radial nerve exit the axilla via?
Triangular interval
What is the blood supply of the triceps brachii muscle?
Profunda brachii artery
Which of the following is a boundary of the cubital fossa?
Lateral epicondyle of humerus
What is the innervation of the anconeus muscle?
Radial nerve
What is the function of the anconeus muscle?
Assist triceps in extending the forearm
Which of the following nerves supplies the muscles in the anterior compartment of the arm?
Musculocutaneous nerve
Which of the following nerves innervate the Brachialis muscle?
Both the musculocutaneous and radial nerves
The brachial fascia extends to which of the following structures?
Both the forearm and arm
What is the function of the bicipital aponeurosis?
Reinforces the wall of the cubital fossa
The cubital fossa is bounded by which of the following structures?
Both the medial and lateral epicondyles
Which of the following arteries supplies the arm?
Only the brachial artery
Which of the following nerves is NOT a branch of the radial nerve?
Median nerve
What is the origin of the short head of the biceps brachii?
Coracoid process
The musculocutaneous nerve innervates which of the following muscles?
Both the biceps brachii and brachialis
The lateral intermuscular septum extends from the deep surface of the brachial fascia to which of the following structures?
Lateral epicondyle
Which of the following muscles is NOT a flexor of the forearm?
Triceps brachii
Which branch of the radial nerve innervates the extensor carpi radialis longus?
Muscular branch in the arm
What is the function of the bicipital aponeurosis?
To protect the brachial artery and median nerve
Which nerve is responsible for detecting noxious stimuli in the dorsal hand and fingers?
Superficial branch of the radial nerve
What is the boundary of the cubital fossa medially?
Lateral border of the pronator teres muscle
Which artery is the continuation of the axillary artery?
Brachial artery
Which nerve innervates the muscles of the flexor compartment of the arm?
Musculocutaneous nerve
What is the superficial branch of the radial nerve responsible for?
Contributing to the cutaneous innervation of the dorsal hand and fingers
What is the clinical significance of the median cubital vein?
It is the vein of choice for venepuncture and intravenous injections
What is the function of the brachial fascia?
To separate the superficial and deep structures of the arm
Which nerve is responsible for the innervation of the extensor muscles of the forearm?
Radial nerve
Study Notes
Anatomy of the Arm
- The arm is divided into two compartments: anterior (flexor) and posterior (extensor)
- Each compartment has its own muscles, nerves, and blood supply
Musculocutaneous Nerve
- Terminal branch of the lateral cord of the brachial plexus
- Pierces the coracobrachialis muscle
- Supplies all the muscles in the anterior compartment of the arm
- Pierces the deep fascia to become cutaneous (superficial)
- Branches:
- Muscular branches
- Lateral cutaneous nerve of the forearm
Radial Nerve
- Terminal continuation of the posterior cord of the brachial plexus
- Lies posterior to the axillary artery
- Exits the axilla via the triangular interval
- Lies in the radial groove, accompanied by the profunda brachii artery
- Supplies the triceps and anconeus muscles
Cubital Fossa
- Triangular region with an apex pointing distally
- Gateway/transition point between the arm and forearm
- Boundaries:
- Medial: lateral border of the pronator teres
- Lateral: medial border of the brachioradialis
- Base: imaginary line between the medial and lateral epicondyles of the humerus
- Floor: brachialis and supinator
- Roof: skin, superficial and deep fasciae, reinforced by the bicipital aponeurosis
- Contents:
- Superficial:
- Median cubital vein
- Upper lateral cutaneous nerve of the forearm
- Medial cutaneous nerve of the forearm
- Deep:
- Median nerve
- Brachial artery
- Biceps brachii tendon
- Radial nerve (deep to the brachioradialis)
- Superficial:
Posterior (Extensor) Compartment
- Extensors of the forearm
- Two muscles:
- Triceps brachii
- Anconeus
- Blood supply: profunda brachii
- Innervation: radial nerve
Triceps Brachii
- Origin:
- Long head: infraglenoid tubercle of the scapula
- Lateral head: posterior shaft of the humerus
- Medial head: posterior shaft of the humerus
- Insertion: common tendon at the olecranon process of the ulna
- Function:
- Main/chief extensor of the forearm
- Assists in adduction of the arm
- Stabilizes the head of the abducted humerus in the glenohumeral joint (long head)
Anconeus
- Origin: lateral epicondyle of the humerus
- Insertion: fibers diverge medially to attach on the lateral aspect of the olecranon process
- Function:
- Assists the triceps in extending the forearm at the elbow joint
- Stabilizes the elbow joint
Clinical Anatomy
- Radial nerve palsy:
- Causes: fracture of the midshaft of the humerus, incorrect intramuscular injection, Saturday night palsy
- Results: loss of function in the extensors of the forearm, hand, metacarpals, and phalanges
- Wrist drop, weakness of adduction and abduction of the hand
- Brachial artery:
- Pulsation: auscultation for manual recording of blood pressure is carried out in front of the elbow
- Clinical anatomy: pulsation is taken in the cubital fossa, which is a gateway between the arm and forearm
This quiz covers the branches of the radial nerve, including its deep and superficial branches, and their functions in the forearm and hand.
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