anatomy of the forearms, cubital fossa and hands Flashcards
what are the 2 parallel bones of the forearm?
the radius and ulna
what connects the 2 parallel bones of the forearm?
the interosseous membrane
which of the 2 bones of the forearm is the rotating one? which is the stabilising one?
ulna → stabilising
radius → pivoting
where does the radius and humorous articulate?
elbow joint
- radial head
- the capitulum of the humerus
where does the ulna and humorous articulate?
elbow joint
- trochlear notch of ulna
- trochlea of humerus
what movements happen at the elbow joint?
flexion and extension
where is the cubital fossa?
what shape is it?
triangular-shaped region anterior to the elbow joint
what are the borders of the cubital fossa?
superior - imaginary line between the epicondyles
lateral - brachioradialis muscle
medial - pronator teres muscle
what are the 3 key structures that cross vertically down through the cubital fossa?
TAN
- tendon (biceps brachii)
- artery (brachial)
- nerve (median)
name the muscles of the SUPERFICIAL anterior forearm
- pronator teres
- flexor carpi radialis
- palmaris longus
- flexor carpi ulnaris
what is the action of the pronator teres?
it pronates the forearm
- supinate is palms and forearm facing up holding (bowel of soup)
- pronate is face down
what are the 2 actions of the flexor carpi radialis
- flexes wrist
- lateral radial deviation (ie. abduction of hand and wrist)
palmaris longus - describe the shape and direction fo travel
- middle, long, big muscle belly - inserts into palmar fascia
what is the action of thepalmaris longus?
weak flexor of the wrist
not always present (30% dont have)
what is the action of the flexor carpi ulnaris?
- flexion
- medial ulnar deviation (ie. adduction of hand and wrist)
what nerves innervate the SUPERFICIAL muscles of the anterior forearm ?
median nerve -PT,FCR,PL
ulnar nerve - FCU
where do the SUPERFICIAL muscles of the anterior forearm originate from?
all originate from medial epicondyle
what is the muscle of the middle anterior forearm?
flexor digitorum superficialis
how many tendons does the flexor digitorum superficialishave?
where do they insert?
- 4
- each tendon splits into 2 and these slips insert on either side of the the middle phalanx of digits 2-5
what is the action of the flexor digitorum superficialis(FDS) ?
flexes digits 2-5 at MCP joints
(Metacarpophalangeal)
and PIP joints (proximal interphalangeal)
what nerve innervates FDS?
median nerve
name the muscles of the DEEP anterior forearm
- Flexor digitorium profundus
- flexor pollicis longus
- Pronator quadratus
Flexor digitorum profundus
- how many tendons arise from this muscle? where do these insert?
4 tendons
- travel into the hand
- onto digits 2-5
- pass through the slits in the FDS tendons
-to insert onto the palmar aspect of thedistalphalanx of digits 2-5.
(finger tip area)
what is the action of the Flexor digitorum profundus?
- flexes digits 2-5
- distal interphalangeal joints (DIPS)
what nerve innervates FDP?
dual innervation
lateral half - median
medial half - ulnar
what is the action of the Flexor policies longus?
flexes the IP joint of the thumb
Interphalangealjoint
what is the insertion of the Flexor pollicis longus (FPL)?
inserts onto thedistal phalanxof the thumb.
describe the location and shape of the pronator quadratus muscle?
deepest forearm muscle
square shaped
lies over the distal ends of the radius and ulnar
what is the action of the Pronator quadratus?
pronates the distal radioulnar joint.
what are the radial and ulnar arteries terminal branches of?
subclavian → axillary → brachial → radial and ulnar arteries
where do the superficial and deep veins of the upper limb drain?
axillary vein
what are the superficial veins of the upper limb?
- the cephalic vein
- the basilic vein
- the communicating median cubitalvein (connects the 2)
what are the deep veins of the upper limb?
radial and ulnar
what is the carpal tunnel?
- narrow passageway at the wrist
- entrance to the palm
what are the borders of the carpal tunnel?
Floor and sides (=carpal arch)
- the carpal bones
roof
- theflexor retinaculum
(fibrous band that’s attached to carpal bones)
what structures pass through the carpal tunnel?
- the 9 tendons of the anterior forearm
- the median nerve
what is carpal tunnel syndrome?
Compression of the median nerve
(very narrow)
weakness and atrophy of the muscles
what are the 8 carpal bones?
from lateral proximal row →
Scaphoid
Lunate
Triquatrum
Pisiform
Hamate
Capitate (central)
Trapezoid
Trapezium (thumb)
which carpal bones does the distal radius articulate with? what joint is this?
- the scaphoid
- the lunate
= the radio carpal joint
what are the 3 sets of bones in the hand?
the carpals
the metacarpals
the phalanges
what is the singular of phalanges?
a phalanx
how are the metacarpals labelled?
numbered 1-5
1 = thumb 5 = little finger
how many phalanges make up each digit?
digits 2-5 = a proximal, middle and distal phalanx (3)
digit 1 (thumb) = a proximal and distal phalanx (2)
what are the 3 different joint types in the hand?
- Carpometacarpal, CMC
- Metacarpophalangeal. MCP
- interphalangeal, IP
what are the interphalangeal joints of the thumb?
only 1 because only a proximal and distal phalanx
what are the interphalangeal joints of the digits 2-5?
PIP- proximal interphalangeal (between proximal and middle phalanges)
DIP- distal interphalangeal (between middle and distal phalanges)
what are the 3 grips the digits can make?
power grip (tight squeeze)
hook grip (eg. carrying bags)
precision grip (pads of thumb and index eg. pen holding)
what are the movements of the digits 2-5?
flexion (curl into fist)
extension (back to neural)
abduction (fingers apart)
adduction (fingers together)
what are the movements of digit 1?
flexion and extension
- thumb across palm, think knife hand
- thumb out to lateral side
abduction and adduction
- thumb away from palm vertically
- thumb back to in line with fingers
opposition
-across palm to touch little finger
what structure of the hand makes it so tough and protects the long flexor tendons, tendon sheaths and vessels in the central palm?
the palmar aponeurosis
where are the extrinsic and intrinsic muscles of the hand?
extrinsic - forearmand their tendons travel into the hand.
intrinsic -origins and insertions arewithinthe hand.
what 2 nerves innervate the intrinsic hand muscles?
ulnar and median
what are the 4 groups of intrinsic hand muscles?
- thenar eminence
- hypothenar eminence
- lumbricals
- interossei
where is the thenar eminence ?
- fleshy mass on the palm of the hand
- at the base of the thumb.
what nerve innervates the muscles of the thenar eminence?
the recurrent branch of the median nerve (from carpal tunnel)
what are the 3 muscles of the thenar eminence?
what actions do they all do?
- abductor pollicis brevis (abducts thumb)
- flexor pollicis brevis (flexion of thumb)
- opponens pollicis
(opposes thumb)
where do each of the muscles of the thenar eminence insert?
APB -onto lateral aspect of proximal phalanx of the thumb
FPB - onto Proximal phalanx
OP - onto 1st metacarpal (deepest)
where is the hypothenar eminence ?
fleshy mass on the medial side of the palm of the hand, proximal to the little finger.
what are the 3 muscles of the hypothenar eminence?
what actions do they all do?
- Flexor digiti minimi (flexes little finger)
- Abductor digit minimi (abducts)
- opponens digiti minimi (opposes)
where do each of the muscles of the hypothenar eminence insert?
FDM - onto proximal phalanx of little finger
ADM - onto proximal phalanx
ODM - onto 5th metacarpal
what nerve innervates the 3 muscles of the hypothenar eminence?
deep branch of ulnar
how many lumbrical muscles are there in the hand?
one per finger
ie. digits 2-5
where do the lumbrical muscles arise from?
the tendons of flexor digitorum profundus
what side of the digits 2-5 do the lumbrical muscles travel along?
the lateral side
where do the lumbrical muscles insert onto?
the dorsal aspects of digits 2-5
what are the actions of the lumbrical muscles?
flex the MCP joints + extend IP joints
what is the innervation of the lumbrical muscles?
same as FDP tendons
dual innervation
- lateral half (digits 2,3) = median nerve
- medial half (digits 4,5) = ulnar nerve
where are the interossei muscles attached to?
lie between the metacarpals
what/where are the 2 different groups of interossei muscles?
palmar - 3 muscles attached to palmar aspect of digits 2,4,5
dorsal - 4 muscles attached to dorsal aspect of digits 2-5
what are the actions of the interossei muscles?
- both groups aid extension at IP joints for digits 2-5
- Palmar ADduct fingers
- Dorsal ABduct fingers
PAD-DAB
why is the intrinsic hand muscle adductor pollicis not in the thenar eminence?
- it is located in the palm, below the eminence
- innervated by ulnar nerve (not median)
where is the adductor pollicis attached?
to the 3rdmetacarpal and to the proximal phalanx of the thumb.
what are the palmer arches?
where the radial and ulnar artereis anastomose deep in the palm
what do the palmer arches give rise to?
metacarpal and digital arteries that supply the palm and digits.
what are the 2 different palmer arches?
superficial and deep
Cutaneous sensation of the hand is supplied by what 2 different types of nerves?
- peripheral nerves
- dermatomes (spinal nerves)
what is a dermatome?
a region of skin innervated by asingle spinal nerve
what are the peripheral nerves the innervate the skin of the hand?
median
ulnar
radial
where does the median nerve innervate on the hand?
palmar surface of the 3.5 lateral digits
+
dorsal distal phalanges of the 3.5 lateral digits (finger tips)
(thumb, index, middle, half of ring )
where does the ulnar nerve innervate on the hand?
- medial 1.5 digits on both palmar and dorsal aspects
half of ring finger, little finger
where does the radial nerve innervate on the hand?
- dorsal surface of lateral 3.5 digits as far as the DIP joint
(backs of fingers, but not tips)
what are the symptoms of damage to median and ulnar nerves at wrist?
sensation to fingers impaired
what plexus and spinal nerves innervates the upper limb?
the brachial plexus (C5-T1)
where does C5 area correspond to?
upper lateral arm
regimental badge
where does C6 area correspond to?
lateral forarm to thumb
where does C7 area correspond to?
middle finger
where does C8 area correspond to?
medial border of hand and medial forearm
where does T1 area correspond to?
medial border of elbow
how many layers of muscles are in the posterior forearm compartment?
2 layers - superficial and deep
what are all the muscles in the posterior forearm compartment innervated by?
theradialnerve
what are the 6 superficial muscles (lateral to medial) in the posterior forearm compartment?
- Brachioradialis
- extensor carpi radialis longus
- extensor carpi radialis brevis
- extensor digitorium
- extensor digit minimi
- extensor carpi ulnaris
where do all 6 of the superficial muscles in the posterior forearm compartment originate from?
attached proximally to thelateral epicondyleof the humerus
ie. the common extensor origin
where does the Brachioradialis muscle insert?
distal radius
what is the action of the Brachioradialis?
weak flexor
where do Extensor carpi radialis longus and Extensor carpi radialis brevis insert?
both on radial side
- ECRL inserts onto 2nd metacarpal
- ECRB inserts onto the 3rdmetacarpal
what are the actions of Extensor carpi radialis longus and Extensor carpi radialis brevis?
they extend and abduct the wrist ( ie. radial deviation)
where does Extensor digitorum insert onto?
inserts onto dorsal aspects of fingers (on extensor expansion)
what is the action of Extensor digitorum ?
extends digits 2-5 via 4 tendons on dorsal aspect
what is the action of Extensor digiti minimi?
extends the little finger via its insertion onto the dorsum of the little finger (on extensor expansion)
where does Extensor carpi ulnaris insert into?
- most medial of the superficial muscles.
- insertion onto the 5th metacarpal.
what are the actions of the Extensor carpi ulnaris?
It extends and adducts the wrist (ie. ulnar deviation)
what is the name of the band of tissue the tendons of the superficial muscles travel under at the wrist?
what is its role?
theextensor retinaculum
prevents the tendons from bowing when the wrist is extended.
what are the 5 deep muscles of the posterior forearm compartment?
From lateral to medial they are
- supinator
- abductor pollicis longus
- extensor pollicis brevis
- Extensor pollicis longus
- extensor indicis
where doe the deep muscles of the posterior forearm compartment originate from?
- attach proximally to forearm bones + interosseous membrane.
- EXCEPT for supinator
where does the supinator originate from?
- proximally to humorous
- wraps around upper radius bone
what is the action of the supinator muscle?
supinates forearm and hand (face up)
where does Abductor pollicis longus insert onto?
1st metacarpal (thumb)
so can abduct thumb
what is the action and insertion of the Extensor pollicis brevis muscle?
- extends thumb from MCP joint
- via its insertion on the proximal phalanx of the 1st digit
what is the action and insertion of the Extensor pollicis longus muscle?
- extends thumb from IP joint
- via its insertion on the distal phalanx of the 1st digit
do the EPB and EPL muscle tendons lie superficially of deeply at the wrist?
the tendons of EPB and EPL lie superficially at the wrist as they wrap around the distal radius
what is the action and insertion of the Extensor indicis muscle?
- inserts onto dorsal aspect of index finger
- allowing independent extension of this digit.
what is the extensor expansion?
where is it attached?
what is its role?
- a fibrous structure that overlies dorsal aspect of the digits
- attached from base of the proximal phalanges
- fixes tenedons in place
what are the 3 ‘slips’ of the extensor expansion ?
central slip → inserts on middle phalanx
2 marginal slips → converge on the distal phalanx.
what 3 tendons are inserted onto the dorsal aspect of the extensor expansion?
- ED - Extensor digitorum (superficial post)
- EI - Extensor indicis (deep post)
- EDM - Extensor digiti minimi (superficial post)
what 2 groups of muscles are inserted onto the sides of the proximal parts of the extensor expansion?
- lumbricals
- interossei
where is the anatomical snuff box?
- lateral aspect of the wrist,
- at the base of the thumb,
- seen when the thumb isextended.
what shape is the anatomical snuff box?
triangular
what are the boundaries of the anatomical snuff box?
the deep posterior muscles that move the thumb:
- the EPL
- the EPB
- the APL
what important structures run through he anatomical snuff box?
- caphoid on the floor
- radial artery
- cephalic vein
- superiorfial branch of radial nerve runs OVER it
what artery supplies posterior Forearm
ulnar arteries
what veins drain the posterior Forearm?
the deep veins
what nerve innervates allthe muscles of the posterior forearm?
radial nerve
what is a potential result of Proximal injuries to the radial nerve (e.g., in the arm)?
an inability to extend the wrist and fingers.
what nerve innervates skin over:
- the anatomical snuffbox
- the skin over thedorsumof thelateral 3 1⁄2 digits as far as the DIP joint
the radial nerve (a superficial branch)
what type of joint is the shoulder joint?
A synovialball and socketjoint
what articulations form the shoulder joint?
articulation between:
- theglenoid fossaof the scapula
+
-theheadof the humerus.
what features of the shoulder joint increase its range of mobility?
- articulates are a poor fit
- joint capsule Is lax
what features of the shoulder joint increase its stability?
- ligaments reinforce the joint capsule
- the rotator cuff
- tendon of the long head of biceps
what type of joint is the elbow joint?
A synovialhinge joint
what articulations form the elbow joint?
- trochlea of the humerus and thetrochlear notch of the ulna,
- thecapitellumof the humerus and theradial head
what type of joints are theproximal and distal radioulnar joints?
Synovial, pivot-type joints between the radius and ulna.
what ligament holds the radial head in place whilst it rotates (to produce pronation and supination)?
Theanular ligamentof the radius is attached to the ulna and holds the radial head in place.
what type of joint is the wrist joint?
a condyloid synovial joint
what articulations form the wrist joint?
articulation of thedistal radiuswith thescaphoidandlunate.
reinforced by ligaments
what type of joins are the carpal bone joints?
synovial joints, which are reinforced by ligaments.
what type of joints are the hand joints?
synovial
metacarpophalangeal - condyloid
interphalangeal - hinge
what joint is key for the movement of the thumb?
Thefirst carpometacarpal(CMC) joint that lies between thetrapeziumand the1st metacarpal (thumb)
saddle joint
