Forearm and Hand
What are the muscles of the extensor compartment of the arm?
Lateral head of triceps Long head of triceps Medial head of triceps
What actions do the muscles of the forearm produce?
Movement of the wrist joint Flexion of the fingers + thumb Pronation of the forearm
What do the muscles of the posterior forearm do?
Movements of the wrist joint Extension of the fingers including the thumb Supination of the forearm
What are the muscles that adducts the digits?
PADs: Palmar Interossei (3 of them) Transverse head of adductor pollicis Oblique head of adductor pollicis
What do the lumbricals do? What innervates them?
The lumbricals flex the metacarpophalangeal joints and extend the interphalangeal joints. The medial lumbricals (3rd and 4th fingers) are innervated by the ulnar nerve. The lateral lumbricals (1st and 2nd fingers) are innervated by the median nerve.
What passes deep to the flexor digitorium superficialis?
The median nerve and the ulnar artery
How many layers of muscles does the forearm have?
Three: Superficial Intermediate Deep
What is the purpose of the synovial flexor sheaths?
To allow tendons to slide freely over each other during movements of the fingers.
Where does the flexor digitorum profundus attach?
To the distal phalanx (finger tips)
Where does the ulnar nerver and artery enter the hand?
On the medial side of the wrist
What does the superficial palmar arch connect to on the lateral side of the hand?
One branch of the radial artery
Where do the muscles of the superficial layer of the posterior forearm attach?
All muscles share a common origin off the supracondylar ridge and lateral epicondyle of the humerus.
What does the superficial branch of the radial nerve innervate?
Only sensory innervation on the dorsal surface of the hand.
How many layers are in the posterior compartments of the forearm?
2: Superficial Deep
Why does lateral epicondylitis get aggrivated by gripping?
Because the attachments for wrist muscles are at the lateral epicondyle
What are the muscles of the superficial layer of the posterior forearm?
Brachioradialis Anconeus Extensor Carpi Radialis Longus Extensor Carpi Radialis Brevis Extensor Digitorum Extensor Digiti Minimi Extensor Carpi Ulnaris
What posterior compartment forearm muscles do not cross the wrist joint?
Brachioradialis and anconeus
What are the deep muscles of the anterior forearm compartment?
Flexor Digitorum Profundus Flexor Pollicis Longus Pronator Quadratus
What route does the radial artery take in the wrist/hand?
It goes to the dorsal side and splits into the dorsal carpal artery and another branch goes palmar side by going through the 1st dorsal interosseous muscle. The radial artery gives off a dorsal carpal branch which anastomoses with a branch of the ulnar artery to form the dorsal carpal arch. The dorsal carpal arch gives rise to dorsal metacarpal arteries which ultimately divide to become dorsal digital arteries.
What does the anterior interosseous artery supply?
It is located in the anterior/flexor compartment but splits off branches to the deep muscles of the posterior compartment (going through the interosseous membrane)
Where is the cubital fossa?
It is the area of transition between the arm and the forearm. It lies between the brachioradialis and pronator teres muscle. The floor is the brachialis.
What happens to the flexor digitorium superficialis and flexor digitorum profundus as it crosses into the hand?
It joins into a common synovial flexor sheath. After entering the hand, they fan out into their respective digital synovial sheaths.
What is the purpose of the extensor retinaculum?
It keeps the tendons down so that it doesn't pop out or bowstring.
Where does the median nerve pass as it goes to the hand?
It passes through the carpal tunnel.
Where are the largest arteries of the forearm?
In the anterior compartment. They pass distally to supply the hand and give rise to branches that supply the posterior compartment.
How many muscles are in the deep layer of the posterior forearm and what are they?
Five: Supinator (Interosseous membrane) Abductor Pollicis Longus Extensor Pollicis Brevis Extensor Pollicis Longus Extensor Indicis
What are the major contents of the cubital fossa?
From lateral to medial: Tendon of biceps brachii Brachial Artery Median Nerve
What arteries does the ulnar artery split into?
It splits into the common interosseous. The ulnar half stays on the ulnar side. The common interosseous splits into the anterior interosseous artery and the posterior interosseous.
What does the deep palmar connect to?
Itcrosses medially in the hand between the metacarpal bones and long flexor tendons of the digits to combine with the deep branch of the ulnar artery.
What is tenosynovitis?
Infection and inflammation of the digital synovial sheaths.
Where does the radial nerve split into superficial and deep branches?
Just deep to the brachioradialis.
What does the superficial palmar arch supply?
It branches into the palmar digital branch to the medial side of the little finger and the common digital arteries.
What happens to the tendons and sheaths with repetitive movements?
It can cause inflammation of the tendons and sheaths resulting in thickening of the fibrous sheath and decreased ability to move the fingers.
What is the action of the flexor pollicis longus?
It causes flexion at the thumb at the MCP and the interphalangeal joint
What does the flexor digitiorum superficialis connect to?
It crosses the wrist, the MCP, and attaches at the PIP joint (it splits) (second from last, the middle phalanx)
Where does the superficial radial nerve go? What kind of nerve is it?
It goes down the forearm deep to the brachioradialis. It is purely a cutaneous nerve.
What are the muscles of the flexor compartment of the arm?
Long head of biceps Short head of biceps Coracobrachialis Brachialis
What is the function of extensor hoods/expansion?
Many intrinsic muscles of the hand insert into the free margin of the extensor hoods and work through the extensor hoods to produce fine movements of the fingers.
What nerve innervates the posterior compartment of the forearm?
Radial nerve or one of its branches.
What is the significance of the anatomical snuffbox?
Scaphoid can be palpated to assess fracture If the scaphoid has a fracture, blood supply may be denied to the proximal portion of the bone, and might degenerate. This would require surgery
What is the action of the brachioradialis?
Since it attaches to the wrist, but doesn't cross it, it does not have action at the wrist. It flexes the forearm at the elbow.
What does the posterior interosseous artery supply?
Some branches contribute to elbow joint. The rest supplies the superficial extensor muscles.
What is the roof of the cubital fossa? What is below the roof?
Superficial fascia and skin. The median cubital vein is below the roof of the cubital fossa.
What forms the extensor hoods?
THe tendons of extensor digitorum and extensor pollicis longus pass onto the dorsal surface of the hand and expand over the proximal phalanges to form the extensor hoods.
What covers the brachial artery and median nerve?
The bicipital aponeurosis.
What joins the common digital arteries and where?
The common digital arteries are joined by branches of the deep palmar arch before bifurcating into proper digital arteries.
Where does the deep branch of the nerve go? What kind of nerve is it?
The deep branch pierces the supinator muscle. The deep branch supplies the muscles of the posterior forearm and contributes to innervation of the elbow.
What does the median nerve of the palm innervate?
The digital branches innervate the fingers up until the lateral half of the ring finger. The palmar branch innervates half way up the palm. The 1st and 2nd lumbricals.
What muscle(s) are in the intermediate layer of the anterior compartment of the forearm?
The flexor digitorum superficialis. It has 2 heads.
Which muscle does not share a flexor synovial sheath?
The flexor pollicis longus.
What are the two heads of the flexor carpi ulnaris? What passes through it?
The humeral head and the ulnar head. The ulnar nerve passes between the two heads of the flexor carpi ulnaris
What separates the anterior flexor compartment from the posterior extensor compartment in the arm?
The intermuscular septa
What separates the anterior and posterior compartments in the forearm?
The interosseous membrane and the intermuscular septum
What are the boundries of the anatomical snuffbox?
The lateral border: Abductor pollicis longus Extensor pollicis brevis Medial border: Extensor pollicis longus Floor: Scaphoid and trapezium Distal ends of extensor carpi radius longus and brevis tendons
What innervates the flexor digitorum profundus?
The lateral half is innervated by a branch of the median nerve. The medial half is innervated by the ulnar nerve.
What are the features of the superficial palm?
The palmar aponeurosis The palmaris brevis muscle The flexor retinaculum THe tendon of palmaris longus
What nerves passes anterior to the carpal tunnel?
The palmar branch of the median nerve passes superficial to the flexor retinaculum. The ulnar nerve (and it's palmar) does not pass through the carpal tunnel.
What artery passes through the anatomical snuffbox?
The radial artery
What forms the deep palmar arch?
The radial artery does, as it crosses between the 2 heads of the 1st dorsal interosseus and then between the two heads of the adductor pollicis to become the deep palmar arch.
Where does the radial artery pass in the forearm and what does it supply?
The radial artery passes distally with the superficial branch of the radial nerve and contributes blood to the hand.
What does the radial artery supply?
The radial artery supplies the extensor muscles on the radial side of the forearm as it travels with the superficial radial nerve.
What does the ulnar nerve innervate at the hands?
The superficial branch innervates the pinky and the medial half of the ring finger halfway down the palm. The palmar branch innervates from forearm to halfway up the palm. The deep branch of the ulnar nerve innervates the Hypothenar Interossei Medial lumbricals (fingers 3 and 4) Adductor pollicis
What does the recurrant branch of the median nerve innervate?
The thenar muscles
What does the deep palmar supply?
The thumb Lateral side of index finger Branches off palmar metacarpal arteries that combine with common palmar digital arteries Forms perforating branches that pass to the dorsum of the hand.
What forms the superficial palmar arch? What is it deep to? What is it superficial to?
The ulnar artery as it crosses laterally across the palm. It is deep to the palmar aponeurosis It is superficial to the long flexor tendons of the digits.
Where does the ulnar artery pass and what does it contribute?
The ulnar artery contributes to the hand, but first it splits off the common interosseous artery that splits into the anterior and posterior interosseous branches.
Where does the ulnar nerve pass through?
The ulnar nerve passes posterior, to the medial epicondyle.
What are the superficial muscles of the anterior forearm? Where do they originate?
There are 4 superficial anterior forearm muscles: Flexor carpi radialis Palmaris longus Flexor Carpi Ulnaris Pronator teres - Pronates the forearm (turn palm down) They all originate on the medial epicondyle of the humerus
What is the purpose of the fibrous digital sheaths?
They are strong ligamentous tunnels that surround the tendons and their synovial sheaths and prevent the tendons from pulling away from the digits (bowstringing)
What are the thenar muscles?
They are the muscles at the thumb: Flexor pollicis brevis Abductor pollicis brevis Opponens pollicis
What are the hypothenar muscles?
They are the muscles that control the little finger: Flexor digiti minimi brevis Abductor digiti minimi Opponens digiti minimi
What does the median and ulnar nerves innervate?
They both travel distally and innervate muscles and skin of the hand.
