Hand and Wrist Flashcards
How much flexion and extension occur at the midcarpal and radiocarpal joints?
flexion:
- 40% radiocarpal
- 60% midcarpal
extension:
- 33% midcarpal
- 67% radiocarpal
What is the extensor expansion?
- the extensor tendons that form a moveable hood over the MP and IP joints of the fingers
- allow for uncoupling of flexion and extension
What muscle allows for a “power” grip?
-flexor digitorum profundus (stronf flexion of MP and IP joints)
How does the median nerve travel through the carpal tunnel?
-it moves from a position between f.d superficialis and f.d. profundus to a position superficial to f.d. superficialis
What is the Dupuytren’s contracture?
- progressive shortening ad thickening of the palmar fascia that pulls the 4th and 5th digits into partial flexion.
- hereditary
How are the long tendons of flexor digitorum superficialis and profundus relate?
- 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
What is tensosynovitis?
- 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
What muscles compose the thenar eminence?
- abductor pollicis brevis
- flexor pollicis brevis
- opponens pollicis
What muscles form the hypothenar eminence?
- flexor digiti minimi
- abductor digiti minimi
- opponens digiti minimi
Origin, insertion, action, and innervation of OPPONENS POLLICIS
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
Origin, insertion, action, and innervation of ABDUCTOR POLLICIS LONGUS
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
Origin, insertion, action, and innervation of FLEXOR POLLICIS BREVIS
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
Origin, insertion, action, and innervation of ADDUCTOR POLLICIS
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
Origin, insertion, action, and innervation of ABDUCTOR DIGITI MINIMI
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
Origin, insertion, action, and innervation of FLEXOR DIGITI MINIMI
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
Origin, insertion, action, and innervation of OPPONENS DIGITI MINIMI
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
Lumbricals
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
Palmar interossei
- 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
Dorsal Interossei
- 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
What are the two carpals joints?
- radiocarpal joint: proximal carpal row (scaphoid and lunate)-radius
- medcarpal joint: distal carpal row- proximal carpal row
