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The medial head of the triceps brachii muscle originates from the lateral supracondylar ridge and the humeral shaft down to the olecranon fossa.
The medial head of the triceps brachii muscle originates from the lateral supracondylar ridge and the humeral shaft down to the olecranon fossa.
False (B)
The radial fossa, which accommodates the head of the radius in full flexion, is located above the trochlea on the anterior surface of the humerus.
The radial fossa, which accommodates the head of the radius in full flexion, is located above the trochlea on the anterior surface of the humerus.
False (B)
At birth, both the upper and lower ends of the humerus are cartilaginous.
At birth, both the upper and lower ends of the humerus are cartilaginous.
True (A)
The centre of the humeral shaft develops a primary ossification centre at the sixth week of fetal development.
The centre of the humeral shaft develops a primary ossification centre at the sixth week of fetal development.
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The anterior surface of the humeral shaft features a shallow coronoid fossa, separated by translucent bone from the olecranon fossa.
The anterior surface of the humeral shaft features a shallow coronoid fossa, separated by translucent bone from the olecranon fossa.
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During surgical exposure of the radial nerve in the arm from a posterior approach, the lateral head of the biceps brachii is detached from the humerus.
During surgical exposure of the radial nerve in the arm from a posterior approach, the lateral head of the biceps brachii is detached from the humerus.
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To expose the infraclavicular part of the brachial plexus, the deltopectoral groove is opened and the pectoralis major muscle is detached from the coracoid process.
To expose the infraclavicular part of the brachial plexus, the deltopectoral groove is opened and the pectoralis major muscle is detached from the coracoid process.
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In cases requiring a more proximal exposure of the brachial plexus, the entire clavicle must always be removed.
In cases requiring a more proximal exposure of the brachial plexus, the entire clavicle must always be removed.
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Damage to the axillary nerve is observed in approximately 15% of shoulder dislocations.
Damage to the axillary nerve is observed in approximately 15% of shoulder dislocations.
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A characteristic sign of axillary nerve damage is a square-shaped area of anesthesia over the outer side of the upper arm below the acromion.
A characteristic sign of axillary nerve damage is a square-shaped area of anesthesia over the outer side of the upper arm below the acromion.
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To assess for potential axillary nerve damage, testing for adduction of the shoulder by the deltoid muscle is recommended.
To assess for potential axillary nerve damage, testing for adduction of the shoulder by the deltoid muscle is recommended.
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The ulnar nerve is most frequently injured in the axilla or at the wrist.
The ulnar nerve is most frequently injured in the axilla or at the wrist.
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The 'claw hand' deformity, associated with a low ulnar nerve lesion, is characterized by hyperflexion of the metacarpophalangeal joints of the ring and little fingers.
The 'claw hand' deformity, associated with a low ulnar nerve lesion, is characterized by hyperflexion of the metacarpophalangeal joints of the ring and little fingers.
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In 'claw hand' resulting from ulnar nerve injury, the metacarpophalangeal joints are hyperextended while the proximal interphalangeal (PIP) and distal interphalangeal (DIP) joints are flexed due to paralysis of interossei and lumbricals.
In 'claw hand' resulting from ulnar nerve injury, the metacarpophalangeal joints are hyperextended while the proximal interphalangeal (PIP) and distal interphalangeal (DIP) joints are flexed due to paralysis of interossei and lumbricals.
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To expose the deep branch of the radial nerve, also known as the posterior interosseous nerve, the pronator quadratus muscle can be incised.
To expose the deep branch of the radial nerve, also known as the posterior interosseous nerve, the pronator quadratus muscle can be incised.
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The claw hand deformity is caused by the unopposed action of the extensor muscles and the flexor digitorum profundus muscle.
The claw hand deformity is caused by the unopposed action of the extensor muscles and the flexor digitorum profundus muscle.
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Paralysis of the ulnar half of the flexor digitorum profundus results in an inability to flex the proximal interphalangeal joints of the ring and little fingers.
Paralysis of the ulnar half of the flexor digitorum profundus results in an inability to flex the proximal interphalangeal joints of the ring and little fingers.
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'Guttering' between the metacarpals is a sign of wasting of the lumbrical muscles.
'Guttering' between the metacarpals is a sign of wasting of the lumbrical muscles.
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Sensory loss due to ulnar nerve damage is always extensive on the ulnar side of the hand and on the little and ring fingers.
Sensory loss due to ulnar nerve damage is always extensive on the ulnar side of the hand and on the little and ring fingers.
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To test the first dorsal interosseous muscle, ask the patient to abduct their index finger.
To test the first dorsal interosseous muscle, ask the patient to abduct their index finger.
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The median nerve lies lateral to the biceps tendon in the cubital fossa.
The median nerve lies lateral to the biceps tendon in the cubital fossa.
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To expose the median nerve in the forearm, the radial head of flexor carpi ulnaris must be detached from the radius.
To expose the median nerve in the forearm, the radial head of flexor carpi ulnaris must be detached from the radius.
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When relieving compression in the carpal tunnel, the flexor retinaculum is incised longitudinally on the radial side of the median nerve.
When relieving compression in the carpal tunnel, the flexor retinaculum is incised longitudinally on the radial side of the median nerve.
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The posterior cutaneous nerve of the arm supplies sensory innervation to a strip of skin along the flexor surface of the arm.
The posterior cutaneous nerve of the arm supplies sensory innervation to a strip of skin along the flexor surface of the arm.
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Triceps brachii, despite having three heads, receives innervation from four branches of the radial nerve.
Triceps brachii, despite having three heads, receives innervation from four branches of the radial nerve.
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The ulnar collateral nerve, a branch of the radial nerve, courses superficial to the ulnar nerve.
The ulnar collateral nerve, a branch of the radial nerve, courses superficial to the ulnar nerve.
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A quick assessment of limb nerve integrity requires testing every muscle supplied by that nerve.
A quick assessment of limb nerve integrity requires testing every muscle supplied by that nerve.
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Complete brachial plexus injuries commonly result from falls on outstretched hands.
Complete brachial plexus injuries commonly result from falls on outstretched hands.
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Damage to the entire brachial plexus can result in Horner's syndrome.
Damage to the entire brachial plexus can result in Horner's syndrome.
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The lower lateral cutaneous nerve of the arm originates from the C7 spinal nerve root.
The lower lateral cutaneous nerve of the arm originates from the C7 spinal nerve root.
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The musculocutaneous nerve is frequently injured in upper limb trauma.
The musculocutaneous nerve is frequently injured in upper limb trauma.
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When testing biceps function, it's crucial to differentiate its action from that of brachioradialis and brachialis, both innervated by the radial nerve.
When testing biceps function, it's crucial to differentiate its action from that of brachioradialis and brachialis, both innervated by the radial nerve.
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The radial nerve innervates Anconeus.
The radial nerve innervates Anconeus.
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The median nerve is most frequently injured at the elbow.
The median nerve is most frequently injured at the elbow.
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Wasting of the thenar eminence is a consistent finding in median nerve injury, with noticeable atrophy over the abductor pollicis brevis due to its singular nerve supply.
Wasting of the thenar eminence is a consistent finding in median nerve injury, with noticeable atrophy over the abductor pollicis brevis due to its singular nerve supply.
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Sensory loss due to median nerve injury is always clearly defined and easy to assess clinically over the radial three fingers and radial side of the palm.
Sensory loss due to median nerve injury is always clearly defined and easy to assess clinically over the radial three fingers and radial side of the palm.
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The "pointing finger" position, with the index finger extended and other fingers flexed, is characteristic of high median nerve lesions.
The "pointing finger" position, with the index finger extended and other fingers flexed, is characteristic of high median nerve lesions.
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The clavicle is generally shorter in broad-shouldered males compared to females.
The clavicle is generally shorter in broad-shouldered males compared to females.
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The medial two-thirds of the clavicle is flattened and curves posteriorly.
The medial two-thirds of the clavicle is flattened and curves posteriorly.
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The clavicle's subcutaneous position makes it palpable and susceptible to injury.
The clavicle's subcutaneous position makes it palpable and susceptible to injury.
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The sternoclavicular joint's articular disc attaches to the inferior and anterior margin of the clavicle's sternal end.
The sternoclavicular joint's articular disc attaches to the inferior and anterior margin of the clavicle's sternal end.
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Flexor carpi ulnaris is involved in the paralysis seen in high median nerve lesions.
Flexor carpi ulnaris is involved in the paralysis seen in high median nerve lesions.
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The median nerve lies between the pisiform bone and the radial artery in the forearm.
The median nerve lies between the pisiform bone and the radial artery in the forearm.
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Study Notes
Upper Limb Anatomy
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Metacarpophalangeal and Interphalangeal Joints: Extensors and flexor digitorum profundus muscles control these joints. Injury above the elbow affects the ulnar half of flexor digitorum profundus, resulting in straighter fingers. Wasting of interossei muscles can reveal "guttering" between metacarpals. Sensory loss occurs on the ulnar hand, little, and ring fingers, but often less than expected.
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Hand Muscle Testing: To assess median nerve function, test abduction of the index finger (first dorsal interosseous). For high-level lesions, assess the ulnar half of flexor digitorum profundus in flexing the little finger's distal interphalangeal joint. For wrist-level lesions, test abductor pollicis brevis.
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Median Nerve: Commonly injured at the wrist (cuts or carpal tunnel compression). Wasting of the thenar eminence can occur. Sensory loss can affect the radial three fingers and the radial side of the palm, primarily over the thumb and index finger pulp pads. High-level lesions cause forearm wasting, as long flexors (except for flexor carpi ulnaris and half of flexor digitorum profundus) and pronators are paralyzed. The hand displays the index finger straight ("pointing finger").
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Ulnar Nerve: Often injured behind the elbow or wrist, leading to a "claw hand." This is characterized by hyperextension of metacarpophalangeal joints of the ring and little fingers and flexion of the distal interphalangeal joints. Interossei and lumbrical paralysis occurs.
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Surgical Approaches: Median nerve exposure is in the arm along the biceps' medial border, adjacent to the brachial artery. At the cubital fossa, it is medial to the biceps tendon. Forearm exposure involves detaching the radial head of flexor digitorum superficialis and turning the muscle medially. Carpal tunnel decompression involves longitudinal incision of the flexor retinaculum on the ulnar side. Ulnar nerve exposure in the upper arm is along the medial border of biceps, adjacent to the brachial artery. At the elbow, it is behind the medial epicondyle. Forearm exposure involves following the nerve from the pisiform, lying between the bone and ulnar artery.
Clavicle
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Structure: The clavicle (collarbone) is longer in males, and its curvatures are usually more pronounced. The medial two-thirds is rounded and convex forward, while the lateral one-third is flat and curves back to meet the scapula. The upper surface is smoother than the lower, especially laterally. The bone lies horizontally and is subcutaneous.
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Parts: The clavicle comprises a shaft, a bulbous sternal end, and a flattened acromial end. The sternal end has a facet for the sternoclavicular joint's disc, attached to the upper and posterior margin of the articular surface.
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Surgical Approach: Exposure of the infraclavicular part involves opening the deltopectoral groove and detaching pectoralis minor to dissect out plexus branches around the axillary artery. The middle part of the clavicle may be removed for more proximal exposure.
Axillary Nerve
- Injury: Damage occurs in about 5% of shoulder dislocations, upper humerus fractures, or misplaced injections into deltoid. Paralysis results, and anesthesia can occur over the outer side of the upper arm below the acromion. Testing for shoulder abduction (by deltoid) can indicate damage. The posterior cutaneous nerve of the arm (C8 and T1) passes back medial to the long head of triceps and supplies skin along the extensor surface of the arm to the elbow.
Radial Nerve
- Injury: In the upper arm, exposure is from the back, detaching the lateral head of triceps from the humerus. Exposure at the elbow involves detaching brachio-radialis and extensor carpi radialis longus from the humerus and turning it forward.
Brachial Plexus
- Injury: Common cause is motorbike accidents, leading to shoulder impact and neck force. If all roots are damaged (rare), the whole limb is immobile and anesthetic. Horner's syndrome might be present. The angle between sternocleidomastoid and clavicle allows for exposure of the plexus.
Musculocutaneous Nerve
- Injury: Rare, tested by assessing biceps' elbow flexion. Brachialradialis (radial nerve) can mimic biceps and brachialis action. Lateral supracondylar ridge is used in surgery.
Injuries
- Diagnostic Overview: Essential muscles and actions can determine nerve integrity without testing every muscle.
Humerus
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Structure: The anterior humerus shows a shallow coronoid fossa, and the olecranon fossa is posteriorly. The trochlea shows a concave part. A shallow radial fossa accommodates the radius' head in flexion. The capsule attaches to the capitulum and trochlea margins and humerus shaft. Synovial membrane connects to the articular margins.
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Ossification: The humerus is cartilaginous at the sixth week, and a primary center appears in the central shaft by the eighth week. Birth marks the upper and lower ends as cartilaginous, with secondary centers appearing, eventually fusing to one epiphysis.
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Surgical Considerations: Posterior shaft exposure involves opening the interval between triceps' long and lateral heads and splitting the medial head vertically. Avoiding profunda vessels and the radial nerve is critical.
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Description
Test your knowledge of upper limb anatomy, focusing on the metacarpophalangeal and interphalangeal joints, muscle testing, and nerve functions. This quiz will assess your understanding of common injuries and their effects on hand function.
