The Hand Flashcards
Name the intrinsic muscles of the hand
- Interossei (7; 3 palmar 4 dorsal)
- Lumbricals (4)
- Thenar eminence (3)
- Hypothenar eminence (3)
- Adductor pollicis (1)
- Palmaris brevis (1)
What is the function of the interossei?
- Flex the straight finger (metacarpophalageal joint)
- Adduction
- Abduction
Which interossei adduct and which abduct?
- PAD and DAB
- Palmar adduct
- Dorsal abduct
What nerve supplies the interossei?
-Ulnar
How do you test the palmar interossei?
- Palm down on a flat surface
- Insert ruler between fingers and try to pull free
How do you test the dorsal interossei?
-Squeeze the fingers together and get patient to try to resist
What are the functions of the lumbricals?
- Extension of the interphalangeal joints
- Flexion of the metacarpophalangeal joint
Where do the lumbricals arise from?
-The 4 tendons of FDP
What nerve serves the lateral to lumbricals?
-median
What nerve serves the medial two lumbricals?
-Ulnar
What is the consequence of denervation of the lumbricals?
- Ulnar claw (medial two)
- Hand of benediction (lateral two)
What three muscles make the thenar eminence?
- Opponens pollicis
- Abductor pollicis brevis
- Flexor pollicis brevis
What nerve supplies the thenar eminence?
-Median
What muscles make the hypothenar eminence?
- Abductor digiti minimi
- Flexor digiti minimi
- Opponens digiti minimi
Where does abductor digiti minimi arise from?
-The tendon of FCU
What nerve supplies the hypothenar eminence?
-Ulnar nerve
What nerve damage is associated with atrophy of the thenar eminence
-Median nerve compression ie carpal tunnel
Where is palmaris brevis?
-Overlays the hypothenar eminence
What nerve supplies palmaris brevis?
-Ulnar nerve
What is the function of palmaris brevis?
- Tightens palmar aponeurosis
- Improves grip by pulling skin of ulnar side of hand to centre
What is the function of adductor pollicis?
-Adduct the thumb
What are the two heads of adductor pollicis?
- Transverse
- Oblique
What nerve supplies adductor pollicis?
-Ulnar nerve
What passes between the two heads of adductor pollicis?
-Radial artery
List the layers of the hand from superficial to deep
- Skin
- Subcutenous tissue
- Fascia
- Palmar aponeurosis
- Muscle compartments
- Carpal bones
What is the carpal tunnel?
- A compartment which passes through the wrist
- Formed by two layers -> carpal arch from capral bones
- Flexor retinaculum forms the roof
What travels through the carpal tunnel?
- 4 tendons of FDS
- 4 tendons of FDP
- Tendon of Floxor pollicis longus
- Median nerve
What is carpal tunnel syndrome?
-Compression of the median nerve within the carpal tunnel
What are the symptoms of carpal tunnel syndrome?
- Aching of the wrist and/or forearm
- Parasthesia of the 1st and second digits
Where does the blood supply to the hand originate from?
-The radial and ulnar arteries
Describe the path of the radial artery after it has passed the wrist
- Crosses the wrist and travels dorsally across the anatomical snuff box
- Gives off a branch proximal to the thumb; superficial palmar branch of radial artery
Describe the path of the ulnar artery after it has passed the wrist
-Passes over flexor retinaculum and divides into deep and superficial branches
What forms the superficial palmer arch?
-The superficial branches of the ulnar and radial arteries
What forms the deep palmar arch?
-Deep branch of ulnar artery anastamoses with radial artery as it passes through the two heads of adductor pollicis
What branches arise from the deep palmar arch?
-Palmar metacarpal arteries
What branches arise from the superficial palmer arch?
-Common palmer digital arteries
What forms the digital arteries?
-Anastomoses of common palmar digital arteries and palmar metacarpal arteries
Describe venous supply to the hand
-A dorsal network of veins drains into the superficial cephalic and basilic veins
What does the median nerve supply in the hand? (motor and sensory)
- Innervates Thenar eminance and lateral two lumbricals
- Sensory innervation of lateral 3 and a half digits, the associated palm (except for small area over thenar eminence) and the back of the 3 and half finger tips
What does the radial nerve supply in the hand?
- No motor function
- Supplies sensory innervation to dorsal lateral 3 and half fingers (except the fingertips) and the associated dorsum
- Also supplies an area over the thenar eminence
What does the ulnar nerve supply in the hand? (motor and sensory)
- Medial 1 and a half fingers and associated palmar and dorsal area
- Medial two lumbricals
- Interossei
- Hypothenar eminence
- Adductor pollicis
- Palmaris brevis
What does the ulnar nerve travel down the forearm with?
-Ulnar artery
How does the ulnar nerve enter the hand?
-Passes over flexor retinaculum through guyons canal
What is the presentation of ulnar claw?
-Hyperextension of the MCP joints and unopposed flexion of the IP joints of the 4th and 5th digits
What causes ulnar claw?
- Long standing ulnar nerve damage at the wrist causing ulnar claw by paralysis of the medial 2 lumbricals (flex MCP + extend IP)
- Hyperextension at MCP occurs because of unopposed extension from extensor digitorum
- Flexion at IP due to unnopposed flexion from FDP
What is ulnar paradox?
-Ulnar claw but to a lesser extent as damaged occurs at the elbow -> FDP damaged so less unopposed flexion
What is the presentation of hand of benediction?
-On attempting to form a fist, there is inability to flex the 2nd and 3rd didgit
What causes hand of benediction to occur?
- Long-term median nerve damage at the elbow causes paralysis of the long flexors in anterior forearm (except FCU and med half FDP) and the lateral two lumbricals
- This results in loss of flexion at the MCP and IP and the inability to make a complete fist producing a claw like shape (4th and 5th digit still work)
