27-01-22 - Hand and Wrist Flashcards
Learning outcomes
- Describe the layers and compartments of the Palm
- Describe the long and short tendons in the hand (Sheaths, extensor hood)
- Describe Thenar, Hypothenar and intrinsic muscles of the hand (attachments, innervation function)
- Compare the effects of different nerve lesions in the hand and forearm (motor and sensory loss as well as clinical appearance and tests)
Superficial Palm.
What is the palmar aponeurosis?
Where is it located?
What 3 things does it allow for in the hand?
Where does the palmaris longus insert?
Where does its tendon spread to?
What does this help it to do?
Where is the flexor retinaculum located in relation to the palmar aponeurosis?
What is another name for it?
What does it form?
Where are its deep attachments?
What is located around the tendons of the digits?
What 3 things do these structures allow?
What is the thenar eminence?
Where is the hypothenar eminence located?
- The palmar aponeurosis is a broad tendinous sheathe attached strongly to the skin and bones of the hand
- It is located in the superficial palm of the hand
• The palmar aponeurosis:
1) Prevents degloving of the hand when gripping
2) Allows for better group
3) Gives protection to deeper structures
- The palmaris longus inserts into the superior end of the superficial palm
- The tendon of palmaris longus inserts into the palmar aponeurosis
- This helps to shape and tense it
- The flexor retinaculum is located more proximal than the palmar aponeurosis
- The flexor retinaculum is also known as the transverse carpal ligament
- It forms the roof of the carpal tunnel
- The flexor retinaculum has deep attachments at the 3rd and 5th metacarpals
• Around the tenons of the digits, there are fibrous digital sheathes caked osseofibrous tunnels which:
1) Help hold the tendon to the bone
2) Prevent bowstringing - Bowstringing is a rare complication of trigger finger release caused by excessive loss of the proximal pulleys
3) Improve efficiency
- The thenar eminence is a bulge located at the base of the thumb, and consists of 3 muscles
- The hypothenar eminence is located at the opposite side of the thumb
What is Dupuytren’s contracture?
Where does this normally happen?
What happens to the digits?
What is the solution to this?
What is this condition linked with?
- Dupuytren’s contracture is the pathological thickening of the palmar aponeurosis
- This normally occurs in the medial side of the palm
- This results in the digits being in a fixed flexed position
- The solution to this is to cut the fibrous attachments between the digits and palm, which is not a great solution, as it will normally form back the same
- This condition is linked with alcoholism
What does the hypothenar compartment of the hand contain?
What does the thenar compartment contain?
What does the central compartment of the hand contain?
What do we have located between compartments in the hand?
Structure is located deep to this?
What is it limited by?
Where does it extend do?
What is located deep to the thenar muscles?
- The hypothenar compartment of the hand is around the hypothenar muscles opposites to the side of the thumb
- The thenar compartment contains the thenar muscles
- The central compartment contains all the long flexors of the digits
- Deep to this we have a potential scape called the midpalmar space
- The midpalmar space is limited medially and laterally by the palmar aponeurosis
- It extends proximal to the wrist, and can be the place where infection can spread from the proximal to distal ends of the wrist and vice versa
- Deep to the thenar muscles, there is a potential space called the thenar space
Long flexor tendons.
What are long flexor tendons?
What do they have when coming under the flexor retinaculum?
Which flexor tendon has a separate sheathe?
What does each digit have?
What is unique about the digiti minimis?
How do the superficial and deep tendons attach to the digits?
- Long flexor tendons are flexor tendons that have come down from the forearm into the hand
- As they pass underneath the flexor retinaculum, they have a synovial sheath around them called the common flexor synovial sheathe of the wrist
- The flexor pollicis longus has a slightly separate synovial sheathe
- Each digit also has a synovial sheathe
- Each digit’s synovial sheathe has a gap, but the digiti minimis synovial sheathe is continuous to the palm, which can cause a spread of infection from the little palm to the wrist
- The superficial tendon can split and insert into the middle phalanx of the digit, while the deep tendon passes through the split e.g tendon of Flexor Digitorum Superificialis (FDS) splits to allow the tendon of Flexor Digitorum Profundus (FDP) through distally
What is inside a fibrous sheathe?
What are the 2 appearances of fibrous sheathes?
What do they form together?
- Inside a fibrous sheathe is a synovial sheathe, inside that is a tendon
- The appearance of fibrous sheathes can either be annular (over the bone) or cruciform (near the joints)
- Together they form an osseofibrous tunnel
Sensory Supply.
Describe what nerves innervate the palmar surface and dorsum of the hand.
Where does the Palmar Cutaneous branch of the Median Nerve come from?
What does this mean for carpal tunnel syndrome?
Where should sensation in these areas be tested?
- The palmar cutaneous branch off the median nerve branches from the median nerve before the carpal tunnel to supply the palm of the hand
- This is why carpal tunnel syndrome should not result in altered sensation in the palm of the hand
- If there is, the lesion is probably more proximal to the carpal tunnel
- Sensation in areas of the hand should be tested away from areas where innervation borders
- This is because these areas of supply and overlap and vary
Palmar nerves.
Where do neurovascular structures lie in the hand?
Where does the ulnar nerve and artery enter into the hand?
What is it formed by?
What does the ulnar nerve and artery do when they come into the hand?
What happens when the ulnar nerve comes into the palm?
What happens when the median nerve comes into the palm?
What does the superficial palmar arch give off?
Where do the nerve and blood supply run up digits?
- Neurovascular structures lie superficially in the hand
- The ulnar nerve and artery do not go through the carpal tunnel
- They go through Guyon’s canal, which is a separate fascial tunnel over the top of the flexor retinaculum
- Guyon’s canal is formed from one of the more proximal fascias of the forearm called the palmar carpel ligament, which is over the top of the transverse carpal ligament
- When the ulnar nerve and artery come into the hand, they throw off a deep branch
- When the ulnar nerve comes into the palm it bifurcates into the webspace to supply the medial side of the third finger, and both sides of the small finger
- When the median nerve comes into the palm it bifurcates in the webspace to supply the lateral side of the third finger, and both sides of the middle and first finger
- The median nerve also throws off a recurrent branch which comes backwards into the thenar eminence to supply the thumb
- The superficial palmar arch gives off digital palmar arteries, which split into proper digital palmar arteries (same principle with nerves)
- In digits, the nerve and blood supply tend to run up the sides of the digits, with some anastomoses at the top
Thenar muscles.
What are thenar muscles associated with?
What are the 4 thenar muscles?
What are their innervations?
Where do all thenar muscles take origin?
Which of these muscles are deep and superficial?
- Thenar muscles are associated with the base of the thumb
- 4 Thenar muscles:
1) Abductor pollicis Brevis
• Innervated by recurrent branch of medial nerve – roots C8 and T1
• Forms more of the anterior bulk of the thenar muscles
• Inserts into the proximal phalanx of the thumb
2) Opponens pollicis
• Innervated by recurrent branch of medial nerve – roots C8 and T1
• Need to remove abductor pollicis brevis to find this lying deeply
3) Flexor pollicis brevis
• 2 heads: Superficial and Deep
• Superficial head is innervated by the recurrent branch of the median nerve – roots C8 and T1
• Deep head receives innervation of the deep Ulnar Nerve – roots C8 and T1
• Inserts into the proximal phalanx of the thumb
•
4) Adductor pollicis
• Has 2 heads: Transverse and Oblique
• Innervated by the deep branch of the ulnar nerve – roots C8 and T1
• Exists in first web space on the medial side of the thumb
• Inserts into a sesamoid bone of the thumb
- All thenar muscles take origin from various carpel bones and the flexor retinaculum
- The Flexor pollicis brevis and Opponens pollicis are deep thenar muscles
- Abductor pollicis brevis and Adductor pollicis are superficial thenar muscles
Hypothenar muscles.
Where are hypothenar muscles located?
What are the 3 hypothenar muscles?
What nerve are they all innervated by?
Where do they all take origin from?
- Hypothenar muscles are located on the medial side of the palm, at the base of the little finger
- 3 hypothenar muscles:
1) Abductor digiti minimi
• On the medial aspect of the little finger
• Responsible for abduction of the little finger
2) Flexor digiti minimi brevis
• More anterior
• Responsible for flexion of the little finger
3) Opponens digiti minimi
• Deep to both of these
• Brings little finger into position with the thumb
- The hypothenar muscles are all innervated by the deep branch of the Ulnar nerve – roots C8 and T1
- All of the hypothenar muscles taken origin from various carpal bones and the flexor retinaculum
How is the extensor hood formed?
How many bands does it have?
How does it spread out over the digit?
What joints in the digits are moved when the extensor digitorum contracts?
What do tendinous connections between extensor digitorum prevent?
What 2 things does the extensor retinaculum provide?
What is the dorsal tubercle useful for?
- Tendons of the extensor digitorum comes into the hand and spreads out to form this extensor expansion called the extensor hood
- It has median and lateral bands to it
- It spreads out over the whole extensor side of the digit
- When the extensor digitorum contracts, the whole digit is extended (meta-carpal phalangeal joint, and the 2 interphalangeal joint)
- Tendinous connections between extensor digitorum prevent you from extending the middle finger when holding down the third finger
- The extensor retinaculum prevents bowstringing and increases efficiency
- The dorsal tubercle is a useful landmark for locating correct tendons
- On the left there is the extensor pollicis brevis
- On the right is the extensor pollicis longus
What are lumbricals?
Where do they take origin?
Where do they insert?
What action does this allow for?
What type of muscles are lumbricals?
What is the innervation of these muscles?
- Lumbricals are worm like muscles
- Lumbricals take origin from the tendons of flexor digitorum profundus, distal to the metacarpal phalangeal joint (muscle arising from another muscle)
- Lumbricals insert into the extensor hood distal to the metacarpal phalangeal joint
- This allows for their action, which is to flex the metacarpal phalangeal joint, whilst also extending the interphalangeal joint
- They pull on the extensor expansion, which extends the interphalangeal joint, but they are doing it distal to the metacarpal-phalangeal joint, so they’ll flex the metacarpal phalangeal joint (like typing)
- The lateral 2 lumbricals are unipennate, while the medial 2 are bipennate arising from adjacent tendons
- The lateral 2 lumbricals are innervated by the median nerve – roots C8 and T1
- The medial 2 lumbricals are innervated by the deep ulnar nerve – roots C8 and T1
What are interossei?
What are the 2 types of interossei?
What are they both considered to be?
How many dorsal interossei are there?
What is their action?
What type of muscles, are they?
How many palmar interossei are there?
What is their action?
What type of muscles are they?
What are all the interossei innervated by?
What can they act together with?
- Interossei are muscles that lie between the bones, more specifically the metacarpals
- Both dorsal and palmar interossei are considered palmar muscles, one group is just deeper than the other, but they are both still on the palmar side
1) Dorsal interossei • There are 4 dorsal interossei • They abduct digits • They are bipennate muscles • DAB – dorsal abduct
2) Palmar interossei • There are 3 palmar interossei • They adduct the digits • They are unipennate • PAD – palmar adduct
- All of these interossei are innervated by the deep ulnar nerve – roots C8 and T1
- The interossei can act together with each other, and other lumbricals to get all the various movements of the digits
Dorsal interossei.
What is the axis of abduction and adduction?
How any dorsal interossei does the middle finger have?
What 2 digits don’t have dorsal interossei?
What is the origin and insertion of dorsal interossei?
What does the first dorsal interosseous muscle have?
What is the primary action of dorsal interossei?
- The axis of abduction (away from middle finger) and adduction (towards the middle finger) is the middle finger
- This means the middle finger has 2 dorsal interossei, because anything the middle finger does is abduction
- The little finger (5th digit) does not have a dorsal interosseous muscle, because it has abductor digiti minimi
- The thumb (1st digit) doesn’t have a dorsal interosseous muscle, because it has to abductors – longus and brevis
- Dorsal interossei take origin at the metacarpals
- They insert a t the proximal phalanx and extensor hood
- The first dorsal interosseous muscle has a gap between its 2 heads, through which the radial artery comes from around the back in the anatomical snuff box and through these 2 heads, at which point it becomes the deeper palmar arch
- The primary action of dorsal interossei is abduction, but they have main different actions
Palmar Interossei.
How many Plasma interossei does the middle finger have?
How many palmar interossei do other digits have?
Where do palmar interossei take origin?
Where do they insert?
What does the thumb have?
- The middle finger has no palmar interossei, as there is no adduction at the middle finger
- The other digits have 1 palmar interosseous muscle called adductor interossei
- They take origin on the adductor side of the metacarpal
- The palmar interossei insert proximal to the phalanx and extensor hood
- The thumb has its own adductor in the form of adductor pollicis
Deep hand
What 3 things does the ulnar nerve innervate?
What does injury to the ulnar nerve present with?
Why is claw hand an ulnar paradox?
How can ulnar nerve injury be tested for?
• The ulnar nerve innervated:
1) Medial 2 lumbricals
2) All interossei
3) 1/2 Flexor Digitorum Profundus
- Injury to the ulnar nerve presents with extension of the MCP joints and flexion at the IP joints
- This because innervation of FDP to those 2 digits and the medial 2 lumbricals has been lost
- This is known as Claw hand
- Claw hand is an ulnar paradox, as normally proximal injuries are worse, but in the case, the more distal the ulnar nerve injury, the more severe the claw hand is.
- Ulnar nerve injury can be tested for using Froment’s sign
- Put a piece of paper between thumb and first finger and ask the patient to hold it
- This uses adductor pollicis
- If they flex the thumb to try and hold is, they are using flexor pollicis brevis and longus, which are not innervated by the ulnar nerve, and instead the medium nerve
- They can also be asked to abduct against resistance, as the ulnar nerve supplies all interossei
What is carpal tunnel syndrome?
What can this lead to?
Why should carpal tunnel syndrome not affect the palm?
How can carpal tunnel syndrome be tested for?
- Carpal tunnel syndrome is compression of the medial nerve in the carpal tunnel
- This can lead to pain or paraesthesia (changes in sensation), and weakness of the thenar muscles in more severe cases?
- Carpal tunnel syndrome shouldn’t affect the palm, because the median nerve branch that supplies the palm comes off before the carpal tunnel
- Pain or paraesthesia in the palm would indicate a more proximal injury
- Carpal tunnel syndrome can be tested for using Phalen’s test, where the patient brings the dorsal side of their hands together
- This should exacerbate carpal tunnel syndrome
What 4 things does the median nerve innervate?
What 2 ways can the medial nerve be tested?
• The median nerve innervates:
1) Lateral 2 lumbricals
2) FDS
3) ½ FDP
4) Thenar muscles
- The medial nerve can be tested by asking the patient to make a fist
- If the first and middle finger wont flex, innervation of all of FDS and ½ FDP has been lost
- The other digits will still have ½ FDP, so can still flex
- This gives the hand of benediction
- Patients can also present with ape hand, which is a loss of opposition due to loss of innervation to thenar muscles
- This also causes thenar muscles to waste
