Hand and Wrist

Question 1

How much flexion and extension occur at the midcarpal and radiocarpal joints?

Answer 1

flexion:
- 40% radiocarpal
- 60% midcarpal

extension:

• 33% midcarpal
• 67% radiocarpal

Question 2

What is the extensor expansion?

Answer 2

• the extensor tendons that form a moveable hood over the MP and IP joints of the fingers
• allow for uncoupling of flexion and extension

Question 3

What muscle allows for a “power” grip?

Answer 3

-flexor digitorum profundus (stronf flexion of MP and IP joints)

Question 4

How does the median nerve travel through the carpal tunnel?

Answer 4

-it moves from a position between f.d superficialis and f.d. profundus to a position superficial to f.d. superficialis

Question 5

What is the Dupuytren’s contracture?

Answer 5

• progressive shortening ad thickening of the palmar fascia that pulls the 4th and 5th digits into partial flexion.
• hereditary

Question 6

How are the long tendons of flexor digitorum superficialis and profundus relate?

Answer 6

• enter a common flexor sheath (ulnar bursa) beneath the flexor retinaculum
• each of the 4 tendons then enters its own separate synovial sheath -> within a fibrous digital sheath
• synovial sheath for digit 5 is continuous with the ulnar bursa

*flexor pollicis longus has a seprate synovial sheath

Question 7

What is tensosynovitis?

Answer 7

• infections in the digital synovial sheaths can cause inflammation of the tendon and synovial sheath.
• for the 5th digit an infection can spread into the carpal tunnel and into the forearm -> continuous with ulnar bursa

Question 8

What muscles compose the thenar eminence?

Answer 8

• abductor pollicis brevis
• flexor pollicis brevis
• opponens pollicis

Question 9

What muscles form the hypothenar eminence?

Answer 9

• flexor digiti minimi
• abductor digiti minimi
• opponens digiti minimi

Question 10

Origin, insertion, action, and innervation of OPPONENS POLLICIS

Answer 10

origin: flexor retinaculum and tubercles of scaphoid and trapezium
insertion: lateral side of 1st metacarpal
actions: oppose thumb and medially rotate 1st metacarpal
innervation: recurrent branch of median nerve

Question 11

Origin, insertion, action, and innervation of ABDUCTOR POLLICIS LONGUS

Answer 11

origin: flexor retinaculum and tubercles of scaphoid and trapezium
insertion: lateral side of base ofproximal phalanx of thumb
actions: abducts thumb, aid in opposition
innervation: recurrent branch of median nerve

Question 12

Origin, insertion, action, and innervation of FLEXOR POLLICIS BREVIS

Answer 12

origin: flexor retinaculum and tubercles of scaphoid and trapezium
insertion: lateral side of base of proximal phalanx of thumb
actions: flexes thumb
innervation: recurrent branch of median nerve and deep branch of ulnar nerve

Question 13

Origin, insertion, action, and innervation of ADDUCTOR POLLICIS

Answer 13

origin: bases of 2nd and 3rd metacarpals, capitate, and adjacent carpals
insertion: medial side of base of proximal phalanx of thumb
actions: adducts thumb
innervation: deep branch of ulnar nerve

Question 14

Origin, insertion, action, and innervation of ABDUCTOR DIGITI MINIMI

Answer 14

origin: pisiform
insertion: medial side of base of proximal phalanx of 5th digit
actions: abducts 5th digit, aids in flexion of 5th proximal phalanx
innervation: deep branch of ulnar nerve

Question 15

Origin, insertion, action, and innervation of FLEXOR DIGITI MINIMI

Answer 15

origin: hook of hamate and flexor retinaculum
insertion: medial side of base of proximal phalanx of 5th digit
actions: flexes proximal phalanx of digit 5
innervation: deep branch of ulnar nerve

Question 16

Origin, insertion, action, and innervation of OPPONENS DIGITI MINIMI

Answer 16

origin: hook of hamate ad flexor retinuaculum
insertion: medial border of 5th metacarpal
actions: brings 5th metcarpal anterior and rotates it to bring into opposition with thumb
innervation: deep branch of ulnar

Question 17

Lumbricals

Answer 17

1st and 2nd:

• attached to lateral 2 tendons of FDP
• median nerve

3rd and 4th:

• attached to medial 3 tendons of FDP
• deep branch of ulnar nerve

-they flex the MP joints and extend tje IP joints of digits 2-5

Question 18

Palmar interossei

Answer 18

• 3 of them
• attach to palmar surfaces of 2nd, 4th, and 5th metacarpals
• insert at bases of proximal phalanges and the extensor expansions of digits 2nd, 4th, and 5th digits
• PAD- adducts 2nd, 4th, adn 5th fingers toward the axial line -> assists lumbricals
• innervated by deep branch of ulnar nerve

Question 19

Dorsal Interossei

Answer 19

• 4 of them
• attach to adjacent sides of 2 metacarpals
• insert at bases of proximal phalanges and the extensor expansions of digits 2-4
• DAB: abducts 2nd-4th fingers toward axial line -> assist lumbricals
• innervated by deep branch of ulnar nerve

Question 20

What are the two carpals joints?

Answer 20

• radiocarpal joint: proximal carpal row (scaphoid and lunate)-radius
• medcarpal joint: distal carpal row- proximal carpal row