Hand Flashcards
Where is the palmar fascia thin and thick? What does it form in the thick part?
Thin over the thenar and hypothenar eminences. Thick centrally, where it forms the palmar aponeurosis.
What number is the thumb and little finger?
Thumb- digit 1
Little finger- digit 5
What is the digital sheath, describe its structure, and what structures does it enclose?
Continuation of the palmar aponeurosis. They are ligamentous tubes. Have 5 annular and 4 cruciform sections. Enclose the synovial sheaths and superficial and deep flexor tendons.
What does the synovial sheath surround and what is its function?
Surrounds each tendon, both in the digits and in the palm. It produce synovial fluid that lubricates the tendon and prevents friction on movement.
Describe the relationship between the synovial sheath and the digital sheath.
Synovial sheath is deeper, and the fibrous digital sheath wraps around it.
Name the muscles in the thenar eminence.
Abductor pollicis brevis
Flexor pollicis brevis
Opponens pollicis
Name the hypothenar muscles.
Abductor digiti minimi
Flexor digiti minimi brevis
Opponens digit minimi.
What nerve innervates the thenar muscles?
Median nerve.
What nerve innervates the hypothenar muscles?
Ulnar nerve.
Name the muscle that adducts the thumb and is in its own separate compartment?
Adductor pollicis.
Where does palmaris brevis originate and insert? What does it overlie and what is its function?
Originates from flexor retinaculum and inserts into dermis. Overlies the hypothenar muscles. Action is to tense the ulnar side of the palm and makes the palm hollow for gripping. It also covers and protects the ulna artery.
What is the function of the lumbricles?
Flex the fingers at the metacarpalphalangeal joints and extend the interphalangral joints.
Which way round are the 4 lumbricles named?
1-4 is medial-lateral.
Where do the lumbricles originate and insert?
Originate at the tendons of flexor digitorum profoundus and insert at extensor portions, so don’t attach to bone.
How many interossei muscles are there?
4 dorsal, 3 palmar.
What action do the lumbricles cause?
Palmar lumbricles adducts, dorsal lumbricles abduct. PAD DAB.
Acting together the lumbricles flex the MCP joint and extend the IP joint.
How do you test the interossei muscles?
Adduction- patient holds paper between fingers, tester should no be able to remove it.
Abduction- patient tries to abduct fingers against tester providing resistance.
What nerve(s) supply the lumbricles?
1 & 2 is supplied by median nerve.
3 & 4 is supplied by ulnar nerve.
What nerve(s) supplies the interossei muscles?
Both palmar and dorsal are supplied by ulnar nerves.
Why is a good blood supply to the hand important?
Hand has a high function, so need a good supply of oxygen and nutrients to the intrinsic muscles.
What is the arterial supply to the hand comprised off?
Ulnar and radial arteries, and their branches.
Talk about the ulna arterial supply to the hand.
Ulna artery enters the hand anterior to flexor retinaculum via the ulnar canal/guyon canal. It then divides into the superficial and deep palmar artery. These then anastomoses with the radial arteries. Gives off further branches from Palmer arch, into a pair of proper palmar digital arteries.
Where does the ulna artery and radial artery supply?
Ulna supplies 3.5 fingers, little to middle. Radial does the rest.
Talk about the venous drainage of the hand.
Superficial and deep venous Palmer arches drain into the forearm veins. On the back of the hand you have dorsal venous network. These veins are used for canulas.
What nerves supply the hand?
Median, radial and ulna.
How does the median nerve enter the hand, and what does it supply?
Enters through the carpal tunnel. Supplies the thenar muscles (loaf):
Lumbricles 1 and 2, Opponens pollicis, abductor pollicis brevis and flexor pollicis brevis.
Palmar cutaneous branch supplies palm. Also supplies lateral 3.5 digits palmar side and finger tips dorsal side.
How does the ulna artery enter the hand?
Via Guyon canal with ulna artery. It’s superficial to flexor retinaculum.
What muscles does the ulna nerve supply?
Lumbricles 3 and 4, Opponens digiti minimi, abductor digit minimi, flexor digiti minimi and interossei.
Supplies medial 1.5 digits on front and back of hand.
What does the radial nerve supply in the hand?
Only supplies skin, no intrinsic muscles. Hit does supply the extensor muscles in the forearm though.
What are the boundaries of the carpal tunnel?
Floor- U shaped carpal bones
Roof- flexor retinaculum
Medial- pisiform and hook of hamate
Lateral- tubercle of scaphoid and trapezium
What is the content of the carpal tunnel?
9 tendons; 4 flexor digitorum superficialis, 4 flexor digitorum profoundus and 1 flexor pollicis longus.
Median nerve.
