forearm and wrist Flashcards
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What is the primary muscle group in the posterior forearm?
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The extensor-supinator muscles.
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Where do the extensor-supinator muscles commonly insert?
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On the lateral epicondyle of the humerus.
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What are the two layers of muscles in the posterior forearm?
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A superficial and deep layer.
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What is the primary function of the key muscles in the posterior forearm?
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They extend the hand and digits (extrinsic function).
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What nerve innervates the posterior forearm muscles?
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The radial nerve.
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Which muscle extends all four fingers (except the thumb)?
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Extensor digitorum.
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Which muscle extends the 5th digit (little finger)?
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Extensor digiti minimi.
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Which muscle extends the wrist and inserts at the base of the 5th metacarpal?
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Extensor carpi ulnaris.
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Which muscle is responsible for supination of the forearm?
Supinator
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Which muscle abducts the thumb?
Abductor pollicis longus.
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Which muscle extends the thumb at the interphalangeal joint?
Extensor pollicis longus.
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Which muscle extends the thumb at the metacarpophalangeal joint?
Extensor pollicis brevis.
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Which muscle extends the index finger?
Extensor indicis.
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What tendons form the boundaries of the anatomical snuff box?
Extensor pollicis longus (EPL) and extensor pollicis brevis (EPB).
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What 3 muscles make up the mobile wad?
Brachioradialis
Extensor carpi radialis longus (ECRL)
Extensor carpi radialis brevis (ECRB)
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Why are these muscles grouped together as the mobile wad?
Because they move during pronation and supination.
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How does the function of the mobile wad muscles change?
Their function changes based on position, and some of these extensor/posterior compartment muscles can have minimal flexor activity.
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What is the function of the extensor carpi radialis brevis and longus?
They are both weak flexors at the elbow joint.
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What is the specific movement of the extensor carpi radialis brevis?
Moves the arm from ulnar abduction to its mid-position and flexes dorsally.
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How does the extensor carpi radialis longus function in different arm positions?
It is a weak pronator in the flexed arm.
It acts as a supinator in the outstretched arm.
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What is the function of brachioradialis?
Brings the forearm into midposition between supination and pronation.
In this position, it acts as a flexor.
In slow movements and a supinated forearm, it has minimal flexor action.
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Which nerve innervates the posterior forearm muscles?
The radial nerve.
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Through which compartment does the radial nerve pass at the elbow?
It passes through the anterior compartment.
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After passing through the elbow, where does the radial nerve travel?
It descends laterally and posteriorly into the posterior forearm.
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What is the name of the branch of the radial nerve that supplies the posterior forearm?
The posterior interosseous nerve.
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What is the name of the anterior forearm compartment?
The flexor-pronator compartment.
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How does the muscle mass of the anterior forearm compare to the posterior forearm?
The anterior forearm contains a larger muscle mass than the posterior forearm.
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What are the two layers of muscles in the anterior forearm?
A superficial layer and a deep layer.
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What key type of muscles does the anterior forearm contain?
Extrinsic muscles that flex the wrist and digits.
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What is the primary nerve innervation of the anterior forearm?
Median nerve (largely), with some contribution from the ulnar nerve.
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What are the main arteries supplying the anterior forearm?
The ulnar artery and the radial artery.
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What type of muscles are the forearm flexors?
The forearm flexors are extrinsic muscles of the hand.
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Where do most forearm flexor muscles arise from?
The medial epicondyle of the humerus.
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Name the 5 major forearm flexor muscles.
Flexor carpi radialis
Palmaris longus
Flexor carpi ulnaris
Flexor digitorum profundus
Flexor digitorum superficialis
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Which 3 forearm flexor tendons are visible in the forearm?
Flexor carpi radialis (FCR)
Palmaris longus
Flexor carpi ulnaris (FCU)
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What percentage of the population lacks the palmaris longus muscle?
About 14% of the population.
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How are the flexor muscles of the forearm categorized?
They are divided into two compartments:
Superficial layer (5 muscles)
Deep layer (3 muscles)
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Where is the median nerve located in the forearm?
It lies between the palmaris longus and the flexor carpi radialis (to the ulnar side of the FCR).
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How can you locate the ulnar nerve and artery in the forearm?
Use the flexor carpi ulnaris (FCU) as a landmark—both the ulnar nerve and artery lie to the radial side of the FCU.
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What is the flexor retinaculum, and what does it form?
The flexor retinaculum, together with the carpal bones, forms the carpal tunnel.
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What 3 structures pass through the carpal tunnel?
Median nerve
Tendons of flexor digitorum profundus
Tendons of flexor digitorum superficialis
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How does the ulnar nerve enter the hand?
The ulnar nerve passes between the hook of the hamate bone and the pisiform bone via the Guyon canal.
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Where can you palpate the radial artery pulse?
The radial artery pulse can be felt in the distal forearm, near the wrist.
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what are the three deep muscles of the anterior flexor compartment?
Flexor digitorum profundus (FDP)
Flexor pollicis longus (FPL)
Pronator quadratus
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Which nerve runs alongside the flexor digitorum profundus (FDP)?
The ulnar nerve.
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label the red box for the innervation of the muscle of the anterior department for MEDIAN NERVE
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label the red box for the innervation of the muscle of the anterior department for ULNAR NERVE
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Arteries of the Forearm-anterior compartment
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Arteries of the Forearm-anterior compartment
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Arteries of the Forearm-anterior compartment
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Arteries of the Forearm-anterior compartment
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Arteries of the Forearm-anterior compartment
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Arteries of the Forearm-anterior compartment
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Arteries of the Forearm-anterior compartment
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Arteries of the Forearm-anterior compartment
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Arteries of the Forearm-anterior compartment
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Veinous drainage-anterior compartment
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Veinous drainage-anterior compartment
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Veinous drainage-anterior compartment
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Veinous drainage-anterior compartment
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Veinous drainage-anterior compartment
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Veinous drainage-anterior compartment
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Veinous drainage-anterior compartment
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Veinous drainage-anterior compartment
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Veinous drainage-anterior compartment
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Veinous drainage-anterior compartment
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Veinous drainage-anterior compartment
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What is the wrist joint also known as?
The radiocarpal joint
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What does the wrist (radiocarpal) joint connect?
The wrist (carpus) with the forearm
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What are the two main bones of the forearm involved in the wrist joint?
ulna and radius
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What are the two main movements of the wrist
Flexion and Extension
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What are the two movements of the wrist
Adduction and Abduction (also called ulnar deviation and radial deviation)
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What is another term for radial abduction and ulnar adduction?
Radial deviation and ulnar deviation
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Which movement is greater: adduction or abduction?
Adduction is greater than abduction
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What limits abduction of the wrist?
The radial styloid process
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What is circumduction?
Circumduction is a movement that consists of successive flexion, adduction, extension, and abduction.
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Which bones form the articulation of the wrist joint?
The articulation is between the radius and the proximal row of carpal bones: scaphoid, lunate, and triquetrum. The ulna is not involved.
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What muscles primarily produce wrist movement?
The "carpi" muscles of the forearm.
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Where do the tendons of the wrist muscles attach?
They extend along the four corners of the wrist and attach to the base of the metacarpals.
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Which muscles are responsible for wrist flexion?
Flexor carpi radialis (FCR)
Flexor carpi ulnaris (FCU)
Some contribution from palmaris longus and abductor pollicis longus
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Which muscles are responsible for wrist extension?
Extensor carpi radialis longus (ECRL)
Extensor carpi radialis brevis (ECRB)
Extensor carpi ulnaris (ECU)
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Which muscles are responsible for wrist abduction (radial deviation)?
Flexor carpi radialis (FCR)
Extensor carpi radialis longus (ECRL) and brevis (ECRB)
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Which muscles are responsible for wrist adduction (ulnar deviation)?
Extensor carpi ulnaris (ECU)
Flexor carpi ulnaris (FCU)
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Which muscles' tendons pass through the carpal tunnel?
Flexor digitorum superficialis (FDS) - 4 tendons
Flexor digitorum profundus (FDP) - 4 tendons
Flexor pollicis longus (FPL) - 1 tendon
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What is a Colles’ fracture?
A fracture of the distal end of the radius, typically a complete transverse fracture, caused by falling on an outstretched hand (FOOSH injury).
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What type of deformity is associated with a Colles’ fracture?
Dinner fork deformity, characterized by dorsal angulation and impaction of the distal radius.
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What additional bone injury is often seen in Colles’ fracture?
Fracture of the ulnar styloid process.
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What is the common cause of a Colles’ fracture?
Falling on an outstretched hand
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What is the most frequently fractured carpal bone?
The scaphoid bone.
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What is the common cause of a scaphoid fracture?
falling on palm
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Where does a scaphoid fracture most commonly occur?
At the narrow part (waist) of the scaphoid bone.
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Why can a scaphoid fracture be easily missed on an X-ray?
It may be misdiagnosed as a sprained wrist and can become more visible later due to bone resorption.
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What artery supplies blood to the scaphoid bone?
The radial artery.
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What is Carpal Tunnel Syndrome (CTS)?
A condition caused by compression of the median nerve within the carpal tunnel, leading to sensory and motor dysfunction in the hand.
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What 3 things commonly causes carpal tunnel syndrome?
Inflammation of synovial sheaths
Increased size of structures passing through the tunnel
Reduction in the size of the carpal tunnel
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What are the 3 symptoms of carpal tunnel syndrome?
tingling, numbness, or absence of sensation in the lateral three and a half fingers
Weakness of the thumb, especially in abductor pollicis brevis (APB) and opponens pollicis
Thenar muscle atrophy, leading to a Simian hand deformity
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What is the treatment for severe carpal tunnel syndrome?
Carpal tunnel release surgery, which involves surgical division of the flexor retinaculum to relieve pressure on the median nerve.
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Why is the surgical incision made toward the medial side in carpal tunnel release?
To avoid injury to the recurrent branch of the median nerve, which supplies the thenar muscles.
