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Questions and Answers
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
'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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
Complete brachial plexus injuries commonly result from falls on outstretched hands.
Complete brachial plexus injuries commonly result from falls on outstretched hands.
Damage to the entire brachial plexus can result in Horner's syndrome.
Damage to the entire brachial plexus can result in Horner's syndrome.
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.
The musculocutaneous nerve is frequently injured in upper limb trauma.
The musculocutaneous nerve is frequently injured in upper limb trauma.
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.
The radial nerve innervates Anconeus.
The radial nerve innervates Anconeus.
The median nerve is most frequently injured at the elbow.
The median nerve is most frequently injured at the elbow.
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.
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.
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.
The clavicle is generally shorter in broad-shouldered males compared to females.
The clavicle is generally shorter in broad-shouldered males compared to females.
The medial two-thirds of the clavicle is flattened and curves posteriorly.
The medial two-thirds of the clavicle is flattened and curves posteriorly.
The clavicle's subcutaneous position makes it palpable and susceptible to injury.
The clavicle's subcutaneous position makes it palpable and susceptible to injury.
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.
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.
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.
Flashcards
Metacarpophalangeal joints
Metacarpophalangeal joints
Joints connecting the metacarpals to the proximal phalanges of the fingers.
Claw hand
Claw hand
A hand condition caused by unopposed extensor action, leading to fingers that cannot flex properly.
Flexor pollicis longus
Flexor pollicis longus
Muscle responsible for flexing the thumb.
Interphalangeal joints
Interphalangeal joints
Joints between the phalanges (finger bones).
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Ulnar nerve exposure
Ulnar nerve exposure
Surgical procedure to access the ulnar nerve in the upper arm.
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Dorsal interosseous
Dorsal interosseous
Muscles that abduct the fingers away from the midline.
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Flexor retinaculum
Flexor retinaculum
Fibrous band over the carpal bones, involved in carpal tunnel syndrome.
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High lesion test
High lesion test
Testing the effect of a high injury on finger flexion.
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Median Nerve Injury
Median Nerve Injury
Injury often occurs at the wrist, affecting hand movement and sensation.
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Thenar Eminence Wasting
Thenar Eminence Wasting
Atrophy of the muscle at the base of the thumb due to nerve damage.
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Sensory Loss Areas
Sensory Loss Areas
Loss of sensation typically in the radial three fingers and palm.
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Clavicle Length
Clavicle Length
The clavicle is approximately 14 cm long in broad-shouldered males.
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Clavicle Curvature
Clavicle Curvature
Curvature varies, with more noticeable curves in males.
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Sternal End of Clavicle
Sternal End of Clavicle
Part of the clavicle that articulates with the sternum.
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Acromial End of Clavicle
Acromial End of Clavicle
The flattened end of the clavicle that connects to the scapula.
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Flexor Carpi Ulnaris
Flexor Carpi Ulnaris
A muscle in the forearm involved in wrist flexion.
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Carpal Tunnel
Carpal Tunnel
A narrow passage in the wrist that can compress the median nerve.
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Pointing Finger Position
Pointing Finger Position
A characteristic hand position associated with median nerve lesions.
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Plexus location
Plexus location
The brachial plexus is located between sternocleidomastoid and clavicle.
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Lower trunk exposure
Lower trunk exposure
Carefully detach the scalenus anterior to expose the brachial plexus.
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Radial nerve pathway
Radial nerve pathway
The radial nerve crosses from back to the radial groove of the humerus.
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Testing wrist extension
Testing wrist extension
Injury to the posterior interosseous branch leads to wrist extension testing.
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Axillary nerve injury
Axillary nerve injury
Injuries to the axillary nerve often occur in shoulder dislocations.
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Claw hand definition
Claw hand definition
A 'claw hand' presents hyperextension at MCP joints of ring and little fingers.
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Anaesthesia area from ulnar nerve damage
Anaesthesia area from ulnar nerve damage
Ulnar nerve injury causes anaesthesia on the outer side of the upper arm.
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Pectoralis minor detachment
Pectoralis minor detachment
Detach pectoralis minor from the coracoid to access the plexus branches.
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Interossei and lumbricals function
Interossei and lumbricals function
Paralysis of these muscles leads to inability to flex fingers.
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Surgical approach to radial nerve
Surgical approach to radial nerve
Detach lateral head of triceps to reveal the radial nerve's pathway.
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Posterior cutaneous nerve of the arm
Posterior cutaneous nerve of the arm
A nerve that supplies skin along the extensor surface of the arm.
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Triceps muscle innervation
Triceps muscle innervation
Triceps is supplied by four branches of the radial nerve.
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Key muscle testing
Key muscle testing
Check nerve integrity by testing a major muscle's action.
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Brachial plexus damage
Brachial plexus damage
Damage to nerve roots often due to trauma, like motorbike accidents.
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Musculocutaneous nerve
Musculocutaneous nerve
A nerve responsible for elbow flexion, rarely injured.
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Horner's syndrome
Horner's syndrome
A condition that may occur with complete brachial plexus injury.
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Anconeus muscle innervation
Anconeus muscle innervation
Innervated by a branch of the radial nerve deep to triceps.
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Ulnar collateral nerve
Ulnar collateral nerve
First branch to the medial head of triceps, runs alongside the ulnar nerve.
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Damage signs
Damage signs
Whole limb immobility and anesthesia indicate severe nerve injury.
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Exploration of nerves
Exploration of nerves
Surgical methods may be needed for nerve exposure or repair.
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Lateral supracondylar ridge
Lateral supracondylar ridge
A bony ridge that spirals up behind the radial groove on the humerus.
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Medial head of triceps
Medial head of triceps
The deep head of the triceps muscle that arises from the humerus shaft.
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Coronoid fossa
Coronoid fossa
A shallow depression on the anterior surface of the humerus above the olecranon fossa.
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Radial fossa
Radial fossa
A shallow fossa on the humerus that accommodates the radius during full flexion.
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Ossification centers
Ossification centers
Locations in the humerus where bone formation begins during development.
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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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