Hand Muscles Flashcards
What is the anterior/lateral border of the anatomical snuff box?
Abductor pollicis longus and extensor pollicis brevis
What is the posterior/medial border of the anatomical snuff box?
Extensor pollicis longus
What are the contents of the anatomical snuff box?
Radial A deep to tendons
Superficial radial N superficial to tendons
Which muscles form the thenar eminence of the hand?
Abductor pollicis brevis, Opponens pollicis, flexor pollicis brevis, adductor pollicis
What are the attachment sites for abductor pollicis brevis?
O: tubercles of the scaphoid and trapezium bones and the flexor retinaculum
I: lateral aspect of the base of the proximal phalanx of the pollux
What is the action of abductor pollicis brevis?
Abduct pollux and aids in opposition
What are the attachment sites for opponens pollicis?
O: tubercles of the scaphoid and trapezium bones and the flexor retinaculum
I: lateral aspect of the 1st metacarpal
What is the action of opponens pollicis?
Oppose pollux
Which thenar muscles are innervated by recurrent branch of the median N?
Abductor pollicis brevis, opponens pollicis and superficial head of flexor pollicis brevis
Which muscles of the thenar eminence are innervated by deep ulnar N?
Deep head of flexor pollicis brevis and adductor pollicis
What are the attachments for flexor pollicis brevis?
O: tubercles of the scaphoid and trapezium bones and flexor retinaculum
I: lateral aspect of the base of the proximal phalanges of the pollux
What is the action of flexor pollicis brevis?
Flex 1st metacarpal and proximal phalanges of the pollux at the carpometacarpal and MP joints
What are the origins for adductor pollicis?
Oblique head: capitate and bases of the 2nd and 3rd metacarpal bones
Transverse head: anterior aspect of the body of the 3rd metacarpal bone
What is the insertion of the adductor pollicis?
Medial aspect of the proximal phalanx of the pollux
What is the action of adductor pollicis?
Adduct pollux
Which muscles form the hypothenar eminence?
Abductor digiti minimi, flexor digiti minimi brevis and opponens digiti minimi
What are the attachment sites for abductor digiti minimi?
O: pisiform bone
I: medial aspect of the base of the proximal phalanx of 5th digit
What is the action of abductor digiti minimi?
Abduct 5th digit
What innervates the muscles of the hypothenar eminence?
Deep ulnar N
What are the attachment sites for flexor digiti minimi brevis?
O: hook of hamate and flexor retinaculum
I: medial aspect of the base of the proximal phalanx of the 5th digit
What is the action of flexor digiti minimi brevis?
Flex proximal phalanx of 5th digit
What are the attachment sites for opponens digiti minimi?
O: hook of hamate and flexor retinaculum
I: medial aspect of the 5th metacarpal
What is the action of opponens digiti minimi?
Oppose 5th digit
Which muscles are considered to be intermediate hand muscles?
1-4th lumbricals, dorsal and palmar interossei
What are the attachment sites for the 1st and 2nd lumbricals?
O: lateral side of the lateral two flexor digitorum profundus tendons as unipennate muscles
I: radial aspect of the extensor expansions of the 2nd and 3rd digits
What is the action of the 1st and 2nd lumbricals?
Flex proximal phalanges of 2nd and 3rd digits
Extend intermediate and distal phalanges of the 2nd and 3rd digits by tightening extensor expansion
What is the action of 3rd and 4th lumbricals?
Flex proximal phalanges of 4th and 5th digits
Extend intermediate and distal phalanges of the 4th and 5th digits by tightening extensor expansion
What innervates most intermediate hand muscles?
Deep ulnar N
Exception: 1st and 2nd lumbricals
What innervates 1st and 2nd lumbricals?
Median N
What are the attachment sites for 3rd and 4th lumbricals?
O: between the medial three flexor digitorum profundus tendons as bipennate muscles
I: radial aspect of the extensor expansions of the 4th and 5th digits
What are the attachment sites for dorsal interossei muscles?
O: adjacent sites of two metacarpals as a bipennate muscle
I: bases of proximal phalanges and extensor expansion of digits 2-4
What is the action for dorsal interossei muscles?
Abduct digits 2-4 (DAB)
Flex proximal phalanges at the MP joint
Extend intermediate and distal phalanges by tightening extensor expansion
What are the attachment sites for palmar interossei muscles?
O: palmar aspect of the 2nd, 4th and 5th metacarpals
I: bases of proximal phalanges and extensor expansions of the 2nd, 4th and 5th digits
What is the action of palmar interossei muses?
Adduct 2nd, 4th and 5th metacarpals (PAD)
Flex proximal phalanges of 2nd, 4th and 5th digits at the MP joint
Extend intermediate and distal phalanges of the 2nd, 4th and 5th digits by tightening extensor expansions
What is a power grip (palm grasp)?
Digits acting against the palm while wrapped around an object with counter pressure from the pollux
Includes involvement from the long flexors of the digits acting at the IP joint with intrinsic hand muscles acting at the MP joint
What is a hook grip?
As when carrying a suitcase
Consumes less energy than the power grip
Involves mainly the long flexors of the digits acting at the IP joint
What is a precision handling grip?
As when writing
Involves long flexor and extensor muscles in addition to the intrinsic hand muscles performing fine movements
What is pinching?
Compressing on object between the distal aspect of the 1st and 2nd digits
What is the position of rest?
Inactive position
