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Questions and Answers
A patient presents with an inability to extend their wrist and fingers. Which nerve is MOST likely affected?
A patient presents with an inability to extend their wrist and fingers. Which nerve is MOST likely affected?
- Musculocutaneous nerve
- Ulnar nerve
- Radial nerve (correct)
- Median nerve
After a deep laceration on the anterior side of the forearm, a patient can no longer flex their distal interphalangeal joints of the 4th and 5th digits. Which nerve is MOST likely damaged?
After a deep laceration on the anterior side of the forearm, a patient can no longer flex their distal interphalangeal joints of the 4th and 5th digits. Which nerve is MOST likely damaged?
- The median nerve
- The musculocutaneous nerve
- The radial nerve
- The ulnar nerve (correct)
A surgeon is performing a procedure to repair a fractured radius. Which arterial structure should they be MOST cautious of to avoid iatrogenic injury during the approach?
A surgeon is performing a procedure to repair a fractured radius. Which arterial structure should they be MOST cautious of to avoid iatrogenic injury during the approach?
- Ulnar artery
- Brachial artery
- Anterior interosseous artery
- Common interosseous artery (correct)
A patient reports loss of sensation on the lateral aspect of their forearm. Which nerve is MOST likely affected?
A patient reports loss of sensation on the lateral aspect of their forearm. Which nerve is MOST likely affected?
A patient presents with an inability to extend their index finger independently. Considering the anatomy of the posterior forearm, which muscle is most likely affected?
A patient presents with an inability to extend their index finger independently. Considering the anatomy of the posterior forearm, which muscle is most likely affected?
Which muscle receives its nerve supply from the axillary nerve?
Which muscle receives its nerve supply from the axillary nerve?
A patient is unable to oppose their thumb and has weakness in wrist flexion. Which nerve would MOST likely be implicated in these deficits?
A patient is unable to oppose their thumb and has weakness in wrist flexion. Which nerve would MOST likely be implicated in these deficits?
Following a deep laceration to the anterior forearm, a patient exhibits weakness in pronation, but retains the ability to flex the digits. Which single nerve is most likely injured?
Following a deep laceration to the anterior forearm, a patient exhibits weakness in pronation, but retains the ability to flex the digits. Which single nerve is most likely injured?
After a fracture of the humerus, a patient is diagnosed with damage to a nerve that affects the posterior aspect of their arm and forearm, as well as the lateral half of the dorsum of their hand. Which nerve is MOST likely involved?
After a fracture of the humerus, a patient is diagnosed with damage to a nerve that affects the posterior aspect of their arm and forearm, as well as the lateral half of the dorsum of their hand. Which nerve is MOST likely involved?
A surgeon is performing a procedure on the anterior forearm and needs to identify the flexor carpi ulnaris. What anatomical landmark can best guide the surgeon to locate this muscle?
A surgeon is performing a procedure on the anterior forearm and needs to identify the flexor carpi ulnaris. What anatomical landmark can best guide the surgeon to locate this muscle?
A patient has lost sensation over the dorsolateral aspect of their hand, but retains normal motor function. Which nerve is most likely affected?
A patient has lost sensation over the dorsolateral aspect of their hand, but retains normal motor function. Which nerve is most likely affected?
An individual has lost the ability to flex their elbow. Which nerve is MOST likely damaged?
An individual has lost the ability to flex their elbow. Which nerve is MOST likely damaged?
A stab wound to the anterior forearm results in paralysis of the flexor carpi ulnaris and impaired flexion of the fourth and fifth digits. Which nerve has MOST likely been damaged?
A stab wound to the anterior forearm results in paralysis of the flexor carpi ulnaris and impaired flexion of the fourth and fifth digits. Which nerve has MOST likely been damaged?
A weightlifter strains their forearm while performing a bicep curl. They experience pain during supination. Which muscle is most likely injured?
A weightlifter strains their forearm while performing a bicep curl. They experience pain during supination. Which muscle is most likely injured?
Which of the following structures is NOT directly supplied by the brachial artery?
Which of the following structures is NOT directly supplied by the brachial artery?
During a wrestling match, an athlete sustains a direct blow to the anterior forearm, resulting in a compromised ability to flex the distal interphalangeal joints of the 2nd and 3rd digits. Which muscle is MOST likely affected?
During a wrestling match, an athlete sustains a direct blow to the anterior forearm, resulting in a compromised ability to flex the distal interphalangeal joints of the 2nd and 3rd digits. Which muscle is MOST likely affected?
A concert pianist reports experiencing numbness and tingling in the thumb, index, and middle fingers. The doctor suspects nerve compression at the wrist. Which of the following muscles is the MOST likely culprit in contributing to the compression?
A concert pianist reports experiencing numbness and tingling in the thumb, index, and middle fingers. The doctor suspects nerve compression at the wrist. Which of the following muscles is the MOST likely culprit in contributing to the compression?
A patient is diagnosed with ulnar nerve entrapment at the wrist. Which of the following clinical findings would MOST likely be observed?
A patient is diagnosed with ulnar nerve entrapment at the wrist. Which of the following clinical findings would MOST likely be observed?
A patient presents with a fracture of the midshaft of the radius. Which of the following muscles' attachments would MOST likely be directly affected by this injury?
A patient presents with a fracture of the midshaft of the radius. Which of the following muscles' attachments would MOST likely be directly affected by this injury?
A surgeon is repairing a laceration in the cubital fossa and needs to identify and protect the median nerve. Which of the following structures serves as the MOST reliable landmark for locating the median nerve in this region?
A surgeon is repairing a laceration in the cubital fossa and needs to identify and protect the median nerve. Which of the following structures serves as the MOST reliable landmark for locating the median nerve in this region?
Flashcards
Common interosseous artery
Common interosseous artery
Arises from the brachial artery and splits into anterior and posterior branches to supply the deep flexor and extensor muscles of the forearm.
Anterior interosseous artery
Anterior interosseous artery
Supplies the deep flexor muscles of the forearm.
Posterior interosseous artery
Posterior interosseous artery
Supplies the extensor muscles of the forearm.
Musculocutaneous nerve
Musculocutaneous nerve
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Axillary nerve
Axillary nerve
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Radial nerve
Radial nerve
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Median nerve
Median nerve
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Ulnar nerve
Ulnar nerve
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Deltoid nerve supply
Deltoid nerve supply
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Brachial Artery
Brachial Artery
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Arm innervation
Arm innervation
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Anterior forearm innervation
Anterior forearm innervation
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Anterior forearm compartment function
Anterior forearm compartment function
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Pronator teres action
Pronator teres action
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Flexor carpi radialis action
Flexor carpi radialis action
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Flexor carpi ulnaris action
Flexor carpi ulnaris action
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Flexor digitorum superficialis action
Flexor digitorum superficialis action
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Extensor carpi ulnaris action
Extensor carpi ulnaris action
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Extensor carpi radialis longus & brevis action
Extensor carpi radialis longus & brevis action
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Extensor digitorum action
Extensor digitorum action
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Study Notes
- These study notes cover the upper limb, specifically focusing on the forearm anatomy.
Forearm Arteries: Anterior
- The brachial artery supplies blood to the anterior forearm.
- The radial and ulnar arteries are also in the anterior forearm.
- The common interosseous artery is located here.
- The anterior interosseous artery supplies blood to the deep flexor muscles of the forearm.
Forearm Arteries: Posterior
- The radius and ulna run along the posterior forearm.
- The common interosseous artery is located here.
- The interosseous membrane sits between the radius and ulna.
- The posterior interosseous artery supplies the extensor muscles of the forearm.
Terminal Branches of Brachial Plexus
- The musculocutaneous nerve is a terminal branch.
- The median nerve is a terminal branch.
- The ulnar nerve is a terminal branch.
- The axillary nerve is a terminal branch.
- The radial nerve is a terminal branch.
Musculocutaneous Nerve
- Motor function is the anterior arm muscles: coracobrachialis, biceps brachii, and brachialis.
- Sensory function is the lateral forearm.
Axillary Nerve
- Motor function is the deltoid and teres minor muscles.
- Sensory function is the deltoid.
Radial Nerve
- Motor function is the posterior arm and forearm muscles.
- Sensory function is the posterior and inferolateral arm, posterior forearm, and lateral half of the dorsum of the hand.
Median Nerve
- Motor function is most anterior forearm muscles.
- Sensory function is the lateral half of the palm of the hand.
Ulnar Nerve
- Motor function is the medial anterior forearm muscles, including flexor carpi ulnaris and the medial half of flexor digitorum profundus.
- Sensory function is the medial half of the dorsum and palm of the hand.
Nerves of the Forearm: Motor
- Axillary nerve controls the deltoid muscle.
- Musculocutaneous nerve controls anterior arm muscles.
- Radial nerve controls posterior arm muscles.
- Median nerve controls the anterior forearm muscles.
- Ulnar nerve (medial) controls the anterior forearm muscles
Cutaneous Innervation (Dermatomes)
- End of axillary nerve controls cutaneous innervation.
- Radial nerve controls cutaneous innervation.
- Lateral antebrachial cutaneous nerve (end of musculocutaneous nerve) controls cutaneous innervation.
- Ulnar nerve controls cutaneous innervation.
- Median nerve controls cutaneous innervation.
Forearm Bone: Radius
- The radius includes the head, radial tuberosity (for biceps brachii attachment), shaft (diaphysis), ulnar notch, and styloid process.
Forearm Bone: Ulna
- The ulna includes the trochlear notch, radial notch, ulnar tuberosity, olecranon (elbow), shaft (diaphysis), and styloid process.
Forearm: Muscle Compartments
- The forearm has posterior, superficial anterior, and deep anterior compartments.
Forearm: Anterior Compartment
- The anterior compartment consists of flexors of the wrist and fingers.
Superficial Anterior Compartment
- The superficial anterior compartment includes muscles from the medial epicondyle to pronator teres (to the radius).
- Other muscles: flexor carpi radialis (to MC2), palmaris longus (to palmar aponeurosis), flexor carpi ulnaris (to MC5), and flexor digitorum superficialis (to middle phalanges of 2nd – 5th digits).
Superficial Anterior Compartment Innervation
- The pronator teres is innervated by the median nerve
- The flexor carpi radialis is innervated by the median nerve.
- The palmaris longus is innervated by the median nerve.
- The flexor carpi ulnaris is innervated by the ulnar nerve.
- The flexor digitorum superficialis is innervated by the median nerve.
Superficial Anterior Compartment Actions
- The pronator teres pronates the forearm and helps flex the forearm at the elbow.
- The flexor carpi radialis flexes the hand at the wrist and abducts the hand.
- The palmaris longus tightens the palmar aponeurosis.
- The flexor carpi ulnaris flexes the hand at the wrist and adducts the hand.
- The flexor digitorum superficialis flexes the phalanges of the digital fingers (not the thumb).
Deep Anterior Compartment
- The deep anterior compartment includes the innervation of the flexor digitorum profundus (median and ulnar nerves).
- Other innervations: flexor pollicis longus (median nerve) and pronator quadratus (median nerve).
Deep Anterior Compartment Actions
- The flexor digitorum profundus flexes the phalanges of the digital fingers (not the thumb).
- The flexor pollicis longus flexes the pollex (thumb).
- The pronator quadratus pronates the forearm.
Forearm: Posterior Compartment
- The posterior compartment consists of extensors of the wrist and fingers.
Posterior Compartment
- The Extensor carpi ulnaris goes to the MC5.
- The Extensor digitorum goes to the digits 2-5.
- The Extensor digiti minimi goes to the 5th digit.
- The Lateral epicondyle is in the posterior compartment.
- The Extensor carpi radialis longus goes to MC2.
- The Extensor carpi radialis brevis goes to MC3.
Lateral Posterior Compartment
- The Brachioradialis goes to the styloid process of the radius.
- Includes both the Extensor carpi radialis longus and brevis.
Anterior Posterior Compartment
- Includes both the Brachioradialis and Extensor carpi radialis longus.
Posterior Compartment- Deep
- Includes the Supinator (to the radius), the Abductor pollicis longus, Extensor pollicis longus, Extensor pollicis brevis, and the Extensor inidicis.
Posterior Compartment and Innervation
- All the the muscles in the posterior compartment are innervated by the radial nerve.
- The extensor digitorum extends the phalanges of the digital fingers digits 2-5.
- The extensor carpi ulnaris extends and adducts the hand at the wrist.
- The extensor digiti minimi extends the phalanges of the pinky.
Deep Posterior Compartment Actions
- Actions of the Supinator is to supinate the forearm.
- The Abductor pollicis longus abducts the phalanges of pollex or the thumb.
- The extensor pollicis longus and brevis extends the phalanges of the pollex or the thumb.
- The extensor inidicis extends the phalanges of the index finger.
Lateral Posterior Compartment Actions
- The the Brachioradialis helps flex the forearm at the elbow.
- The Extensor carpi radialis longus and brevis extends and abducts and hand at the wrist.
Tendons
- Tendons of the extensor digitorum connect the extensor digitorum muscles to the fingers.
- The flexor digitorum superficialis and flexor carpi ulnaris can be seen with a flexed wrist and hand.
- The palmaris longus and flexor carpi radialis are visible tendons in the wrist area.
- The 1st dorsal interosseous and Adductor pollicis are located in the hand/thumb.
- The tendon of the of Extensor Pollicis Longus and Brevis (EPL, APL and EPB) are by the anatomical snuff box.
Bursa and Tendon Sheath
- Tendon Sheaths located at the wrist on the anterior and posterior side which keeps tendons in place.
- FLEXOR RETINACULUM is located in the anterior side of the tendons and wrist.
- EXTENSOR RETINACULUM is located in the posterioride the tendons and wrist.
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