the hand Flashcards
How many creases are present on the surface of the digits?
3
What are the three creases present on the palmar surface of the digits?
Distal digital crease
Middle digital crease
Proximal digital crease
what do the 3 creases resent on the palmar surface of the digits correspond to?
Distal digital crease (corresponds to the DIP joint)
Middle digital crease (corresponds to the PIP joint)
Proximal digital crease (does not overlay a joint, as MCP is more proximal)
What is the significance of the long thenar crease?
It partially encircles the thenar eminence and overlies the metacarpophalangeal (MCP) joint.
What joints do the metacarpal bones articulate with at the wrist?
Carpometacarpal (CMC) joints
What forms the metacarpophalangeal (MCP) joints?
The articulation of the metacarpal bones with the proximal phalanges.
What forms the knuckles that are visible in a closed fist?
The heads of the metacarpals.
How do the interphalangeal joints differ in the thumb compared to other digits?
The thumb has only one interphalangeal (IP) joint.
The other digits have two:
- Proximal interphalangeal (PIP) joint
- Distal interphalangeal (DIP) joint
What provides lateral stability to the MCP, PIP, and DIP joints?
Collateral ligaments.
What tendons are visible on the dorsal side of the hand?
EPL tendon (Extensor Pollicis Longus)
APL & EPB tendons (Abductor Pollicis Longus & Extensor Pollicis Brevis)
How many carpal bones are in the wrist, and how are they arranged?
There are 8 carpal bones, arranged in 2 rows of 4.
What are the two rows of carpal bones?
Proximal row: Scaphoid, Lunate, Triquetrum, Pisiform (red)
Distal row: Trapezium, Trapezoid, Capitate, Hamate (blue)
What are the three sections of the phalanges in each digit?
Proximal phalanx (P1)
Middle phalanx (P2) (not in the thumb)
Distal phalanx (P3)
What are the metacarpals, and how are they numbered?
The five long bones of the hand, numbered 1 to 5 from thumb (1) to little finger (5).
Which carpal bones articulate with the radius?
The scaphoid, lunate, and triquetrum articulate with the radius.
Is the ulna involved in the articulation of the wrist?
No, the ulna is not involved in the wrist articulation.
What is a fully opposable thumb, and which species have it?
A fully opposable thumb is a unique feature of humans and other apes, allowing for precise gripping and manipulation.
How do some anatomists define opposition of the thumb?
Opposition occurs when the thumb is brought to the fifth digit (little finger), whereas apposition refers to contact between the thumb and other digits.
What are the six primary movements of the thumb?
Abduction – Thumb moves away from the palm.
Adduction – Thumb moves toward the palm.
Extension – Thumb moves outward in a straight line.
Flexion – Thumb bends toward the palm.
Opposition – Thumb moves across the palm to touch the fingers.
Reposition – Thumb returns to its normal position after opposition.
abduction
adduction
extension
flexion
opposition
reposition
How are the muscles that move the skeletal elements of the hand divided?
They are divided into intrinsic and extrinsic groups.
Where are extrinsic muscles located, and what movements do they control?
They are found in the anterior and posterior compartments of the forearm and control flexion and extension of the hand.
Which 5 muscles are part of the forearm flexors?
Flexor carpi radialis
Palmaris longus
Flexor carpi ulnaris
Flexor digitorum profundus
Flexor digitorum superficialis
Where do the forearm flexors arise from?
The medial epicondyle of the humerus.
Which 3 tendons are visible in the forearm?
Flexor carpi radialis (FCR)
Palmaris longus
Flexor carpi ulnaris (FCU)
What percentage of the population is missing the palmaris longus?
About 14% of the population.
Where is the median nerve located in relation to forearm muscles?
It lies between the palmaris longus and the flexor carpi radialis, on the ulnar side of FCR.
Why is the flexor carpi ulnaris (FCU) a useful anatomical landmark?
It helps locate the ulnar nerve and artery, which lie to its radial side.
Which muscles control the flexion of the fingers?
The flexor digitorum profundus and flexor digitorum superficialis.
Where do the finger flexors lie in the wrist?
They are located on the ulnar side of the wrist alongside the median and ulnar nerves and the ulnar artery.
What happens when the flexor carpi ulnaris and flexor carpi radialis act together?
They flex the wrist when acting together.
What happens when the flexor carpi ulnaris and flexor carpi radialis contract separately?
They cause deviation to their respective sides.
Where does the flexor carpi radialis (FCR) insert?
It inserts at the base of the 2nd metacarpal.
Where does the flexor carpi ulnaris (FCU) insert?
It inserts at the pisiform, hook of hamate, and 5th metacarpal.
Where does the flexor digitorum profundus (FDP) insert
It inserts at the distal phalanges at the DIP joint.
Where does the flexor digitorum superficialis (FDS) insert?
It inserts at the middle phalanges at the PIP joint.
What muscle extends all four fingers (excluding the thumb)?
Extensor digitorum
Which muscle extends the 5th digit?
Extensor digiti minimi
Where does the extensor carpi ulnaris insert?
At the base of the 5th metacarpal
Where does the extensor carpi radialis longus insert?
At the base of the 2nd metacarpal
Where does the extensor carpi radialis brevis insert?
At the base of the 3rd metacarpal
How many compartments are the intrinsic muscles of the hand divided into?
Five compartments.
What are the five compartments of the hand?
Thenar
adductor
hypothenar
central (lumbricals)
interosseous compartments.
Where are the interosseous compartments located?
Between the metacarpals.
what is the green and yellow space called
Thenar space (green)
Midpalmar space (yellow)
What are the three hypothenar muscles?
Abductor digiti minimi
Flexor digiti minimi brevis
Opponens digiti minimi
What muscles form the thenar eminence?
Abductor pollicis brevis
Flexor pollicis brevis
Opponens pollicis
What is the innervation of the thenar muscles?
The recurrent branch of the median nerve.
What are the three thenar muscles?
Abductor pollicis brevis
Flexor pollicis brevis
Opponens pollicis
What is the function of the adductor pollicis?
Adducts the thumb and provides grip.
What is the innervation of the adductor pollicis?
Ulnar nerve.
What are the lumbricals, and how many are present in the palm?
There are four lumbricals; 2 of which are in the palm
What nerve and artery are seen near the hypothenar muscles?
Ulnar nerve
Ulnar artery
What is the function of the lumbricals?
The lumbricals flex the digits at the MCP joints and extend the IP joints. They place the fingers in the writing position.
How many lumbricals are there?
There are four lumbricals (1st-4th).
What are the two types of interossei muscles, and how many of each are there?
Dorsal interossei (1st-4th)
Palmar interossei (1st-3rd)
What is the function of the dorsal interossei muscles?
Abduct the 2nd-4th digits.
Act with the lumbricals to flex the MCP joint
What is the function of the palmar interossei muscles?
Adduct the 2nd, 4th, and 5th digits.
Assist lumbricals in flexing the MCP joint.
What is the key difference between the insertion sites of dorsal vs. palmar interossei?
contrasting insertion sites between dorsal and palmar interossei.
What is being tested in the palmar interossei test?
The ability to adduct the fingers (palmar interossei action).
Which nerve is responsible for the palmar interossei muscles?
The ulnar nerve.
How is the palmar interossei test performed?
the examiner tries to pull a piece of paper away from the patient’s fingers, which are holding it between them.
What is being tested in the dorsal interossei test?
The ability to abduct the fingers (dorsal interossei action).
which nerve is responsible for the dorsal interossei muscles?
The ulnar nerve.
How is the dorsal interossei test performed?
The examiner tries to push the patient’s fingers together, while the patient attempts to keep them spread apart.
Which two nerves supply all motor innervation to the hand?
The median nerve and the ulnar nerve.
How does the median nerve enter the hand?
It enters via the carpal tunnel and is often involved in carpal tunnel syndrome.
What muscles does the median nerve supply in the hand?
Three short thenar muscles
First and second lumbricals (digits 2 and 3)
How does the ulnar nerve enter the hand?
It passes between the hook of the hamate and the pisiform bone in the Guyon canal.
What 4 muscles does the ulnar nerve supply in the hand?
Hypothenar muscles
Ulnar 2 lumbricals (digits 4 and 5)
Adductor pollicis
All interosseous muscles
What is the role of the radial nerve in the hand?
The radial nerve does not supply motor branches to intrinsic hand muscles but provides sensory branches to the dorsal aspect of the hand.
What are the two main arteries supplying blood to the hand?
The ulnar artery and the radial artery.
What do the ulnar and radial arteries form in the hand?
The superficial palmar arch and deep palmar arch through an anastomosis.
Why are the hands of the somatosensory homunculus oversized?
The oversized hands represent the large amount of cerebral cortex devoted to controlling the approximately 40 muscles and 27 bones of the hand.
What does the somatosensory homunculus illustrate?
It illustrates the disproportionate amount of the cerebral cortex devoted to controlling different body parts, with a focus on sensory input.
What is Skier’s thumb?
An injury to the ulnar collateral ligament of the metacarpophalangeal joint, which supports the thumb during pinching or gripping.
What happens if the ulnar collateral ligament is damaged?
It may lead to chronic instability of the thumb, causing functional problems.
How does Skier’s thumb commonly occur?
It happens when falling onto an outstretched thumb, especially if the thumb is gripping something at the same time.
Why is this injury called Skier’s thumb?
It is commonly caused by falling while skiing while holding a ski pole.
Which ligament supports the thumb during pinching and gripping?
The ulnar collateral ligament of the metacarpophalangeal joint.
What is a mallet finger injury?
A tear of the tendon that straightens the end joint of the finger.
How does a mallet finger injury commonly occur?
It is often caused by catching the finger “end-on” during sport but can also result from minor injuries like catching the finger when tucking in bed sheets.
What happens if the tendon tears at the end bone of the finger?
The tendon may tear where it joins the end bone, or it may pull off a small fragment of bone, which is called a mallet fracture.
What is trigger finger?
A painful condition in which a finger or thumb clicks or locks as it bends towards the palm.
What causes trigger finger?
Thickening of the mouth of a tendon tunnel leads to roughness of the tendon surface, causing the tendon to catch in the tunnel mouth.
Which group of people is especially prone to trigger finger?
People with insulin-dependent diabetes.
Can trigger finger occur in people without diabetes?
Yes, most trigger digits occur in people without diabetes.
What can sometimes trigger the onset of trigger finger?
It occasionally starts after an injury, such as a knock on the hand.
is there evidence that work activities cause trigger finger?
There is little evidence that work activities cause it, but pain can be aggravated by hand use at work, home, in the garden, or during sports.
What condition is trigger finger sometimes associated with?
It is sometimes due to tendon nodules in people with rheumatoid arthritis.
Is trigger finger caused by osteoarthritis?
No, it is not caused by osteoarthritis.
What is another name for Dupuytren’s contracture?
Viking’s disease or Celt’s disease.
What is Dupuytren’s contracture?
A disease of the palmar fascia that causes progressive shortening, thickening, and fibrosis of the palmar fascia and aponeurosis.
Which fingers are most commonly affected by Dupuytren’s contracture
The 4th and 5th digits (ring and little fingers).
is Dupuytren’s contracture usually unilateral or bilateral?
It is frequently bilateral.
What is the cause of Dupuytren’s contracture?
The cause is unknown.
What is the usual treatment for Dupuytren’s contracture?
Surgical excision of fibrotic tissue.
Which joint at the base of the thumb commonly becomes arthritic with age?
The universal joint between the metacarpal and trapezium bones.
What causes osteoarthritis?
Loss of the smooth cartilage surface covering the ends of the bones in the joints, leading to thinning and roughening of cartilage, causing the bone ends to rub together.
At what age does osteoarthritis usually appear?
It can develop at any age but usually appears after the age of 45.
What are some risk factors for osteoarthritis?
It may run in families and can sometimes follow a fracture involving the joint many years before.
What is the difference between rheumatoid arthritis and osteoarthritis based on the slide?
Rheumatoid arthritis: An autoimmune condition.
Osteoarthritis: A result of “wear and tear.”
there is a worksheet on prosection of the hand on keats
