Hand Flashcards
what occurs when metacarpals are injured?
Ventral displacement: pulled anteriorly by interossei muscles
Common injury bc hands are used a lot
what are the joints of the hand?
- carpometacarpal joints
- MP joints
- IP joints
what are the muscles of the 3 layers of the extrinsic muscles of the hand?
where do they insert?
- superficial layer: palmaris longus (fuses with retinaculum and continues to fingers)
- intermediate layer: flexor digitorum superficialis (bifurcates at the medial phalange and inserts on the middle phalange of the medial 4 digits)
- deep layer: Flexor digitorum profundus (Inserts on the distal phalange) + Flexor pollicis longus
what are the intrinsic muscles of the hand?
- thenar muscles
- lumricals
- hypothenar muscles
what are the thenar muscles?
what is their action?
- Opponens pollicis (deep to APB & FPB)
- Abductor pollicis brevis
- Flexor pollicis brevis
- Adductor pollicis (not always grouped bc it has diff. innervation) DRAGON WITH 2 HEADZ
a. Oblique head
b. Transverse head
action: move thumb
what are the lumbrical muscles?
what is their action?
- 1st & 2nd (flex MP, extend IP)
- 3rd & 4th (same)
- Dorsal interossei 1st & 4th
- Palmar interossei 1st & 3rd
action: move pinky
what are the hypothenar muscles?
what is their action?
- Abductor digiti minimi (superficial & lateral)
- Flexor digiti minimi brevis (superficial & medial)
- Opponens digiti minimi (deep to ADM & FDM)
- Palmaris brevis: subdermal (muscle under skin)
a. Very thin running transversely
Movement: not much
what innervates intrinsic muscles of the hand?
median and ulnar nerve
what intrinsic muscles are innervated by median nerve?
2 LOAF o 2 = lumricals 1 & 2 o L = lumbrical o O = opponens pollicis o F = flexor pollicis brevis o Everything else is ulnar n
what is the vasculature of the hand?
how does it travel?
all hand muscles supplied by radial and ulnar arteries
o Radial artery travels deep to abductor pollicis longus + enters snuffbox
• Lies on top of scaphoid bone + supplies posterior had
what is the action of the extensor digitorum communis?
Common extensor for 4 digits
what is the action of the extensor indicis proprius?
main extensor of hand but assisted by EDC
what are the intrinsic muscles of the dorsal hand?
no muscles
interossei muscles are on PALMER hand
what are the main nerves of the hand?
median nerve (anterior interosseus, recurrent branch, volar branch, palmar cutaneous)
ulnar nerve (superficial + deep branches, palmar cutaneous, dorsal branch, branch from superficial terminal, volar branch)
how does the median nerve travel?
travels deep to bicipital aponeuroses→goes deep alongside flexor digitorum superficialis & pronator teres→wrist where it is attached to the FDS
what happens when the median nerve is injured in the elbow?
what is affected?
what are symptoms?
during venipuncture when taking blood, fracture of median epicondyle
o Affects all muscles innervated
o “Hand of benediction:” seen when median n. is damaged. Ask pt to clench fist and only pinky + ring finger clenches or fx’s normally bc they are innervated by the ulnar n
what happens when the median nerve is injured in the wrist?
what is affected?
what are symptoms?
carpal tunnel syndrome caused by displacement of the lunate bone OR inflammation of the ulnar bursa
• Affects muscles of thenar compartment (thumb in flexion + no opposition)
• Abduction of thumb occurs bc abductor pollicis longus moves thumb
what are real life examples of median nerve injury?
slitting wrist superficial (laceration)
cutting with knife deep causes damage to recurrent branch of median n.
In skin: sensation lost in parts of digits 2, 3 + 4
where is the anterior interosseous nerve?
Deep to pronator quadratus. (IS NOT A BRANCH OF THE HAND)
how does the recurrent branch of the median nerve travel?
what does it innervate?
Travels deep to flexor retinaculum
Innervation: 3 intrinsic aka thenar muscles
o Flexor pollicis brevis (only superficial)
o Opponens pollicis
o Abductor pollicic brevis
what does the digital aka volar branches innervate?
Innervation of skin: Supplies digits 2, 3 & 4
Innervation of muscles: supplies lumbricals 1 & 2
how does the palmar cutaneous branch of the median nerve travel and what does it innervate?
how does carpal tunnel affect it?
travels superficial to the flexor retinaculum
• supplies the skin of the radial side of the palm
• carpal tunnel syndrome doesn’t affect this branch bc it doesn’t enter the carpal tunnel
how does the ulnar nerve travel?
travels medially in arm until it twists around the medial epicondyle (ulnar groove) and emerge into forearm and travels to flexor carpi radialis then travels between 2 layers of retincaulum
how does the ulnar nerve enter the hand?
Travels in an ulnar sheath with the ulnar artery to enter the hand superficially (not under carpal tunnel)
travels in between volar & transverse carpal ligaments of flexor retinaculum
how does the ulnar nerve split in the hand?
enters between pisiform and hook of the hamate where it splits into the superficial and deep terminal branches
what is the sensory innervation of the hand?
what parts of the hand do they supply?
palmar cutaneous n.: arises in forearm and enters the hand
o innervates both the palmar + dorsal skin of the medial part of the hand
dorsal branch: innervate parts of the 4th + 5th digits
branch from superficial terminal: innervate the skin over the hypothenar eminence
volar digital branches: supplies the parts of the 4th + 5th digits
what is the motor innervation of the hand?
what muscles do they supply?
superficial terminal branch supplies Palmaris brevis then continues as a sensory nerve
deep terminal branch supplies FPB (deep head), AP, ADM, FDMB, ODM, lumbrical 3 + 4, dorsal interossei, palmar interossei
where does ulnar nerve injury occur?
elbow, distal ulna, wrist
what are the symptoms of ulnar nerve injury and what does it affect?
symptoms: “claw hand”
o lumbrical parlayzed (aided in extension of Interphalageal joints)
o inability to adducts digits and thumb
affect hypothenar, dorsal + palmar interossei
• can lead to atrophy
• sensory deficits on dorsal and palmar aspect of the hand
what else can cause ‘claw hand’?
fracture of distal ulnar will also cause “claw hand” but may not see sensory loss
