Hand and Wrist Flashcards
What is the palmar aponeurosis?
A broad tendinous sheathe attached strongly to the skin and bones of the hand
It is located in the superficial palm of the hand
What does the palmar aponeurosis do?
1) Prevents degloving of the hand when gripping
2) Allows for better group
3) Gives protection to deeper structures
Where does the palmaris longus insert?
Inserts into the superior end of the superficial palm
Where does the tendon of the palmaris longus spread?
Into the palmar aponeurosis; this helps to shape and tense it
Where is the flexor retinaculum located in relation to the palmar aponeurosis?
The flexor retinaculum is located more proximal than the palmar aponeurosis; also known as transverse carpal ligament
What does the flexor retinaculum form?
The form of the carpal tunnel
Where are the deep attachments of the flexor retinaculum?
At the 3rd and 5th metacarpals
What is located around the tendons of the digits?
Osseofibrous tunnels
What 3 things do osseofibrous tunnels allow?
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
What is the thenar eminence?
The thenar eminence is a bulge located at the base of the thumb, and consists of 3 muscles
Where is the hypothenar eminence located?
The hypothenar eminence is located at the opposite side of the thumb
What is Dupuytren’s contracture?
Dupuytren’s contracture is the pathological thickening of the palmar aponeurosis
This results in the digits being in a fixed flexed position
This condition is linked with alcoholism
Where does Dupuytren’s contracture happen?
On the medial side of the palm
What is the solution to Dupuytrens contracture
to cut the fibrous attachments between the digits and palm, which is not a great solution, as it will normally form back the same
What does the hypothenar compartment of the hand contain?
The hypothenar compartment of the hand is around the hypothenar muscles opposites to the side of the thumb
What does the thenar compartment contain?
The thenar compartment contains the thenar muscles
What does the central compartment of the hand contain?
The central compartment contains all the long flexors of the digits
What structure is in between the compartments?
Fibrous septae
What is deep to the central compartment?
Midpalmar space
What is the midpalmar limited by?
The midpalmar space is limited medially and laterally by the palmar aponeurosis
Where does the midpalmar space extend to?
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
What is located deep to the thenar muscles?
Thenar space
What are long flexor tendons?
Long flexor tendons are flexor tendons that have come down from the forearm into the hand
Which flexor tendon has a separate sheathe?
The flexor pollicis longus has a slightly separate synovial sheathe
What is unique about the digiti minimis?
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
How do the superficial and deep tendons attach to the digits?
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?
Inside a fibrous sheathe is a synovial sheathe, inside that is a tendon
What are the 2 appearances of fibrous sheathes?
The appearance of fibrous sheathes can either be annular (over the bone) or cruciform (near the joints)
Describe what nerves innervate the palmar surface and dorsum of the hand.
The palmar cutaneous branch off the median nerve branches from the median nerve before the carpal tunnel to supply the palm of the hand
Where do neurovascular structures lie in the hand?
Neurovascular structures lie superficially in the hand
Where does the ulnar nerve and artery enter into the hand?
Guyon’s canal, which is a separate fascial tunnel over the top of the flexor retinaculum
What happens when the ulnar nerve comes into the palm?
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
What happens when the median nerve comes into the palm?
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
What does the superficial palmar arch give off?
The superficial palmar arch gives off digital palmar arteries, which split into proper digital palmar arteries (same principle with nerves)
Where do the nerve and blood supply run up digits?
In digits, the nerve and blood supply tend to run up the sides of the digits, with some anastomoses at the top
What are thenar muscles associated with?
Thenar muscles are associated with the base of the thumb
What are the 4 thenar muscles?
1) Abductor pollicis Brevis
2)Opponens pollicis
3)Flexor pollicis brevis
4)Adductor pollicis
What is the abductor pollicis brevis innervated?
By the recurrent branch of medial nerve C8 and T1
What is the abductor pollicis brevis form?
Form more of the anterior bulk of the thenar muscles
Where does the abductor pollicis brevis?
Inserts into the proximal phalanx of the thumb
What innervates the opponens pollicis?
Innervated by recurrent branch of medial nerve – roots C8 and T1
What are the 2 heads of the flexor pollicis brevis?
Superficial and deep
What is the superficial head flexor pollicis brevis innervated by?
Innervated by the recurrent branch of the median nerve
What is the deep head of flexor pollicis brevis innervated by?
Deep Ulnar nevre
Where does the flexor pollicis brevis insert?
Into the proximal phalnx of the thumb
Where do thenar muscles take origin?
various carpel bones and the flexor retinaculum
What are the 2 heads of the abductor pollicis?
Has 2 heads: Transverse and Oblique
What innervates the adductor pollicis?
Innervated by the deep branch of the ulnar nerve
Where does the adductor pollicis insert?
Sesamoid bone of the thumb
Which of the thenar muscles are deep and superficial?
The Flexor pollicis brevis and Opponens pollicis are deep thenar muscles
Abductor pollicis brevis and Adductor pollicis are superficial thenar muscles
Where hypothenar muscles located?
Hypothenar muscles are located on the medial side of the palm, at the base of the little finger
What are the 3 hypothenar muscles?
- Abductor digiti minimi
- Flexor digiti minimi brevis
- Opponens digiti minimi
What nerve are hypothenar innervated by?
Deep branch of the ulnar nerve
How is the extensor hood formed?
Tendons of the extensor digitorum comes into the hand and spreads out to form this extensor expansion called the extensor hood
How many bands does the extensor hood have?
It has median and lateral bands to it
What joints in the digits are moved when the extensor digitorum contracts
When the extensor digitorum contracts, the whole digit is extended (meta-carpal phalangeal joint, and the 2 interphalangeal joint)
What do tendinous connections between extensor digitorum prevent?
Tendinous connections between extensor digitorum prevent you from extending the middle finger when holding down the third finger
What 2 things does extensor retinaculum provide?
Tendinous connections between extensor digitorum prevent you from extending the middle finger when holding down the third finger
What are lumbricals?
Worm like muscles that take origin from the tendons of flexor digitorum profundus, distal to the metacarpal phalangeal joint
Where do lumbricals insert?
Insert into the extensor hood distal to metacarpal phalangeal joint
What action do lumbricals allow for?
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)
What type of muscles are lumbricals?
The lateral 2 lumbricals are unipennate, while the medial 2 are bipennate arising from adjacent tendons
What is the innervation of these muscles?
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?
Interossei are muscles that lie between the bones, more specifically the metacarpals
What are the 2 types of interossei
Dorsal and Palmar
However, both are considered palmar muscles
Describe Dorsal interossei
1) Dorsal interossei
* There are 4 dorsal interossei
* They abduct digits
* They are bipennate muscles
* DAB – dorsal abduct
Describe Palmar interossei
There are 3 palmar interossei
* They adduct the digits
* They are unipennate
* PAD – palmar adduct
What are all the interossei innervated by?
Innervated by the deep ulnar nerve C8 and T1
What can interossei act together with?
Can act together with each other, and other lumbricals to get all the various movements of the digits
How many dorsal interossei does the middle finger have?
2
What is the origin and insertion of dorsal interossei?
Dorsal interossei take origin at the metacarpals
They insert at the proximal phalanx and extensor hood
What does the first dorsal interosseous muscle?
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
What is the primary action of dorsal interossei?
Abduction
How many palmar interossei does the middle?
No palmar interossei
Where do palmar interossei take origin and insert?
They take origin on the adductor side of the metacarpal
The palmar interossei insert proximal to the phalanx and extensor hood
What 3 things does the ulnar nerve innervate?
1) Medial 2 lumbricals
2) All interossei
3) 1/2 Flexor Digitorum Profundus
What does injury to the ulnar nerve present
Injury to the ulnar nerve presents with extension of the MCP joints and flexion at the IP joints
Why is claw hand an ulnar paradox?
proximal injuries are worse, but in the case, the more distal the ulnar nerve injury, the more severe the claw hand is.
What is carpal tunnel syndrome?
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?
Why should carpal tunnel syndrome not affect the palm?
because the median nerve branch that supplies the palm comes off before the carpal tunnel
How can carpal tunnel syndrome be tested for?
Phalen’s test, where the patient brings the dorsal side of their hands together
What is pronator teres syndrome?
Pronator teres syndrome is when the median nerve that runs between the ulnar and humeral heads of the pronator teres becomes impinged
This condition is exacerbated by pronation against resistance
What can be an indication of radial neve damage?
Radial nerve damage can be indicated by changes in sensation of the dorsum of the hand
What occurs if damage is high up?
If the radial nerve is injured high up enough, this will cause wrist drop, as innervation has been lost to muscles of the posterior compartment
