Anatomy - Muscles of the forearm Flashcards
Basic movement of digits
Abduction and adduction
Thumb - extension, flexion, adduction, abduction, opposition
Superficial muscles of anterior forearm
Flexor carpi radialis
Flexor carpi ulnaris
Palmaris longus
Pronator Teres
Common flexor origin in forearm
Medial epicondyle
Flexor carpi muscles action
Flex wrist
Flexor carpi radialis
Passes to lateral side of wrist
Flexor carpi ulnaris
Proximally, attaches to humerus and ulna
Passes to medial side of wrist
Palmaris longus function
Flexion of wrist
Palmaris longus
Most superficial muscle
A vestigial muscle, absent in some individuals
Pronator Teres
Most lateral muscle in anterior forearm
Passes to proximal radius
Pronates forearm
Intermediate and deep muscles of anterior forearm
Flexor digitorum superficialis
Flexor digitorum profundus
Flexor pollicis longus
Pronator quadratus
Flexor digitorum superficialis
Proximally has humeroulnar and radial heads
Runs through carpal tunnel and splits into 4 tendons - one for each lateral 4 digits
Flexes digits at MCP and PIP joints
Flexor digitorum profundus
Found deep to superficiais
Runs through carpal tunnel and spots into 4 tendons
Flexes digits at MCP, DIP and PIP joints
Flexor pollicis longus
Proximally, attaches to radius
Passes laterally to thumb (pollex)
Flexes thumb
Pronator quadratus
Quadrangular muscle passing between distal ends of radius and ulna
Superficial muscles of posterior forearm
Brachioradialis Extensor digitorum longus Extensor carpi radialis longus Extensor carpi radialis brevis Extensor carpi ulnaris
Common extensor origin
Lateral epicondyle
Muscles used in wrist adduction
Flexor carpi ulnaris
Extensor carpi ulnaris
Muscles used in wrist abduction
Flexor carpi radialis
Extensor carpi radialis (longus and brevis)
Brachioradialis
Flexes elbow
Proximally, attaches to distal humerus
Passes to lateral radius
Extensor digitorum longus function
Extends medial four fingers at the MCP and IP joints
Extensor digitorum longus attachments
Proximally attaches to common flexor origin
Splits into 4 tendons - one for each digit
Extensor carpi radialis muscles
Extends and abducts wrist
Extensor carpi radialis longus
Passes from distal humerus to base of 2nd metacarpal
Extensor carpi radialis brevis
Depp to radialis longus
Attaches to base of 3rd metacarpal
Extensor carpi ulnaris
Proximally, attaches to common extensor origin
Passes to base of 5th metacarpal
Deep muscles of posterior forearm
Supinator Abductor pollicis longus Extensor pollicis longus Extensor pollicis brevis Extensor indices
Supinator
Passes between proximal ends of ulna and radius
Supination of forearm
Abductor pollicis longus
Proximally, attaches to middle of ulnar and radius
Passes to base of pollex
Extensor pollicis longus
Proximally, attaches to middle 1/3rd of radius
Passes to distal phalanx of thumb
Extensor pollicis longus function
Extends at MCP and CMC joints of thumb
Extensor indices
Single tendon passing to index finger
Extends the index finger
Innervation of deep muscles in posterior forearm
Radial nerve - deep for motor function and superficial for sensory
What do the carpal bones articulate with to form the wrist joint
Radius
Formation of carpal tunnel
Carpal bones to flexor retinaculum
Intrinsic vs extrinsic muscles of hand
Intrinsic have no cause outside the hand
Extrinsic muscles belly lie outside of the hand
Extrinsic muscles of hand
Flexor digitorum profundus and superficialis
Flexor pollicis longus
Extensor digitorum longus - attaches at dorsal surface distally
Extensor digiti minimi
Extensor indices
Extensor pollicis longus/ brevis
Abductor pollicis longus
Muscles in index finger
Flexor digitorum profundus (only attaches at distal phalanx) and superficialis (attaches at both phalanx)
Flexor retinaculum
Strong, fibrous band that passes between medial and lateral carpal bones
Forms the roof of carpal tunnel and stops the long flexor tendons from bowstringing
Tendons of flexor digitorum superficialis
Distally, splits and attaches to either side of the middle phalanges of the lateral 4 digits
Flexor sheath
Fibre-osseous tunnel prevents bow stringing of long flexor tendons, attaches from bone to bone and lined by synovium.
Extensor expansions
Anchor extensor tendons to middle of finger
Pulleys
Thickening found in the flexor sheath (annular and cruciate), keep tendons close to bony skeleton and joints therefore increasing power of flexion by preventing bowstringing
Causes of nodules in fingers
Infl of synovial sheath
Trigger fingers
Get stuck in extension and not extension as powerful flexors can overcome increased friction of enlarged nodule being pulled through A1 pulley by weaker extensors cannot pull it back
Treatment of trigger fingers
Division of A1 pulley (surgery) after unsucessful steroid injection
What happens if too many pulleys divided
Tendons bowstring away from phalanges as finger flexes, loosing power and being uncomfortable
Lumbricals
Anterior to MCP
Posterior to PIP and DIP
Proximal attachment on FDP tendon - palmar/ flexor
Vital attachment into extensor expansion - dorsal/ extensor
Action of lumbricals
Allows flexion of MCPs and extension of IP’s - needled to pick up objects
Intrinsic hand muscles
Lumbricals
Thenar muscles
Flexor pollicis brevis
Abductor pollicis brevis
Opponens pollici
Hypothenar muscles
Flexor digiti mininimi brevis
Abductor digit minimi
Opponens digiti minimi
What are interosseous muscles responsible for
Abduction and adduction of fingers
Palmar interossei muscles
Little, ring and index (adduct)
Dorsal interossei muscles
Middle finger (abduct)
Anterior carpi muscles
Flex wrist
Posterior carpi muscles
Extend wrist
Radial carpi muscles
Abduct wrist
Ulnar carpi muscles
Adduct wrist
Mid prone position
Also known as position of functions in-between supine and prone
Why are there more radial muscles
Radial muscles abduct wrist and keep hand level in mid-prone position
Types of grip
Power
Precision
Pinch (key pinch)
Hook
Power grip
Requires ulna side of hand for span and power
Precision grip
Can be achieved w/ little and ring finger if loss of function of index and middle finger
What can affect a pt’s grip
Any disease process affecting:
Bony skeleton e.g. arthritis or fracture
Muscle function w.g. tendon rupture or weakness
Nerve supply e.g. nerve decompression, demyelination
Common starting point for all grips
Extension of fingers
Extension and adduction of the thumb
Extension of the wrist
Treatment of avulsion fractures of phalanges
Splint in extension to avoid swan neck (flexed DIP and hyperextended PIP) and so tendon can heal and reattach
Sensory aspect of radial nerve
Small area between the dorsal aspect of the 1st and 2nd metacarpals
Typical mechanism of radial nerve injury
Humeral midshaft fracture
Palsy results in wrist drop
Myotomes of radial nerve
C5-C8
Sensory aspect of median nerve
Palmar aspect of lateral 3½ fingers
Myotomes of median nerve
C6, C8, T11
Sensory aspect of ulnar nerves
Medial 1½ fingers
Typical mechanism of ulnar nerve injury
Medial epicondyle fracture
Damage may result in a ‘claw hand’
Myotomes of ulnar nerve
C8, T1
Muscles in forearm innervated by ulnar nerve
Adductor pollicis
Flexor carpi ulnaris
Muscles in forearm innervated by medial nerve
LOAF muscles
