Lecture 9 - Muscles Acting on the Hand Flashcards
functions of the hand
- > grasp power
- > pinch precision
- > feel
- > comunicate
the hand must have…
- > strong mobile framework
- > non slip, pliable gripping surface
- > strong muscles without bulk
- > sensitivity to internal and external environments
characteristics of the skin
- > ridges
- > sweatglands in the ridges
- > fibrous septa (connects dermis to underlying fascia)
- > fat between septa (no room for expansion if infected)
bones and joints of the hands
thumb only has two phalanx but digets 2-5 have 3
finger movements
Add/Abduction
Flex/Extend
intrinsic vs extrinsic muscles of the hand
Extrinsic muscles have their origin on the forearm and have long tendons than insert into the hand
Intrinsic muscles originate inside the hand and insert on the hand
main groups of intrinsic muscles
- > interossei
- > lumbricals
- > thenar muscles
- > hypothenar muscles
muscles that flex the fingers from the forearm
AKA extrinsic finger flexors
- > flexor digitorum superficialis
- > flexor digitorum profundus
OIIA of flexor digitorum superficialis
Origin
Humeroulnar head: med epicondyle of humerus, ulnar collateral ligament, coronoid process of the ulna
Radial head: superior half of the ant border of the radius
Insertion
- > shafts of the middle phalanges of digits 2-5
Innervation
- > median nerve
Action
- > flexes the middle phalanges at the proximal IP joints, can also flex MCP joints and wrist with stronger contractions
OIIA of flexor digitorum profundus
Origin
- > prox ¾ of medial and ant surface of ulna and interosseous membrane
Insertion
- > base of distal phalanx of digits 2-5
Insertion
- > Medial part: ulnar nerve Lateral part: interosseus branch of median nerve
Action
- > flexes distal phalanges at distal IP joints of medial 4 digits, assists with wrist flexion
muscles that extend the fingers from the forearm
AKA extrinsic finger extensors
- > extensor digitorum
- > extensor indicis
- > extensor digiti minimi
OIIA of extensor digitorum
Origin
- > lateral epicondyle of humerus
Insertion
- > extensor expansions of medial four digits
Innervation
- > deep branch of the radial nerve
Action
- > extends d2-5 at metacarpophalangeal joints, extends hand at wrist joint
OIIA of extensor digiti minimi
Origin
- > lateral epicondyle of humerus
Insertion
- > extensor expansion of the 5th digit
Innervation
- > deep branch of radial nerve
Action
- > extends D5 at the metacarpophalangeal joints
OIIA of extensor indicis
Origin
- > posterior surface of ulna and interosseous membrane
Insertion
- > extensor expansion of 2nd digit
Innervation
- > post interosseous nerve and the continuation of the deep branch of the radial nerve
Action
- > extends 2nd digit and helps extend hand at the wrist joint
thumb movements
muscles that act on the thumb from the forearm
AKA extrinsic thumb muscles
- > flexor pollicis longus
- > abductor pollicis longus
- > extensor pollicis longus
- > extensor pollicis brevis
OIIA of flexor pollicis longus
Origin
- > ant surface of radius and adjacent interosseous membrane
Insertion
- > base of distal phalanx of thumb
Innervation
- > anterior interosseous nerve from median nerve
Action
- > flexes thumb phalanges
OIIA of abductor pollicis longus
Origin
- > post surface of ulna, radius and interosseous membrane
Insertion
- > base of 1st metacarpal
Innervation
- > posterior interosseous nerve, the continuation of the deep branch of the radial nerve
Action
- > abducts thumb and extends it at the carpometacarpal joint
OIIA of extensor pollicis longus
Origin
- > post surface of middle ⅓ of ulna and interosseous membrane
Insertion
- > base of distal phalanx of thumb
Innervation
- > post interosseous nerve, the cont of the deep branch of the radial nerve
Action
- > extends distal phalanx of thumb at CM and IP joints
OIIA of extensor pollicis brevis
Origin
- > post surface of radius and interosseous membrane
Insertion
- > base of proximal phalanx of thumb
Innervation
- > post. interosseous nerve, the continuation of the deep branch of the radial nerve
Action
- > extends proximal phalanx of thumb at CM joint
anatomical snuff box
- > radial artery passes through it
OIIA of interossei
7 muscles
- > 3 Palmar
- > 4 dorsal
Origin
- > shafts of metacarpals
Insertion
- > bone and extensor expansion of the proximal phalanges 2-5
Innervation
- > deep branch of the ulnar nerve
Action
the abduct and adduct the fingers
OIA of lumbricals
4 lumbricals
Origins
- > 1 and 2: lat tendons of Flexor Digitum Profundus; unipennate
- > 3 and 4: medial three tendon of FDP; bipennate
Insertion
- > lat sides of the extensor expansion of D2-5
Innervation
- > median nerve and deep branch of ulnar nerve
Action
- > flexes MCP and extend IP joints of D2-5
Hypothenars
- > Abductor digiti minimi
- > flexor digiti minimi
- > opponens digiti minimi
~ palmaris brevis
what is the palmaris brevis and what does it do?
- > muscle located in the subcutaneous tissue of the hypothenar eminence
- > deppens the hallow of the palm to aid in a palmar grip
- > protects ulnar artery
thenar muscles
- > abductor pollicis
- > flexor pollicis brevis
- > opponens pollicis
~ adductor pollicis
adductor pollicis
adducts and flexes thumb MP joint
- > 2 heads; transverse and oblique
MCP joints have what kind of ligaments
collateral
stability/mobility of CMC joints
D1 - Mobile
D2 - Stable
D3 - Stable
D4 - Mobile (15-30 degs of flexion)
D5 - Mobile
palmar aponeurosis
thick triangle of long flattened tendon
- > thenar, hypothenar, and adductor compartment
mallet injury
caused by direct force to the tip of the finger
- > results in damage/injury to the extensor digitorum tendon
nerves of the hand
Median
Ulnar
Radial
