Forearm/Hand anatomy Flashcards
medial boundary of cubital fossa
Mass of medial flexor muslces arising from common flexor attachement on medial epicondyle - mainly pronator teres
lateral boundary of cubital fossa
mass of extensor forearm muscles from lateral epicondyle - mainly brachioradialis
Floor of cubital fossa
brachialis and supinator
Roof of cubital fossa
The continuity of the brachial and antebrachial deep fascia - reinforced by the bicipital aponeurosis, subcutaneous tissue and skin
Contents of cubital fossa
Brachial artery lying between the biceps tendon and the median nerve. The beginning of the radial and ulnar arteries.
Deep accompanying veins of the arteries.
Biceps brachii tendon.
Median nerve.
Radial nerve - deep between brachioradialis and brachialis - it divides into its superficial and deep branches here.
Superficial cubital fossa
Median cubital vein.
Cephalic and Basilic veins.
Median and lateral cutaneous nerves of forearm.
Superficial flexor/pronator muscles
Pronator teres, FCR, PL, FLU. The superficial muscles cross the elbow joint.
Intermediate layer of flexor/pronator muscles
FDS, Does cross the elbow joint
Deep layer of flexor/pronator muscles
FDP, FPL, Pronator quadratus. The deep muscles do not cross the elbow joint.
How is brachioradialis a mojor exception to the rule?
It is a flexor of the forearm but is located in the posteriolateral extensor compartment and it is supplied by the radial nerve.
The long flexors of the digits; FDP and FDS also flex which joints?
MCPJs and wrist
FDS attaches to ___ and flexes ___ joints.
Middle phalanges and PIPJs
FDP attaches to ___ and flexes ___ joints
Distal phalanges and DIPJs
The most lateral superficial forearm flexor
PT
FRC’s distal course and attachment
Passes through a canal in the lateral part of the flexor retinaculum and through a vertical groove in the trapezium in its own synovial tendinous sheath of the FCR
radial arter lies ____ to FCR
Lateral
PL is absent in ___ % of people
14% usually on the left side
ulnar nerve relation to FCU
Ulnar nerve enters the forearm by passing between the humeral and ulnar heads of proximal FCU
FCU innervation
Ulnar nerve
Relationship of ulnar nerve and artery to FCU tendon
Ulnar nerve and artery lie lateral to FCU tendon at wrist
FDS is the largest superficial flexor of forearm True or False
True
Which nerve and artery passes between the proximal attachments of the FDS.
Median nerve and Ulnar artery
What are the two proximal attachements of FDS?
Radial head and humeroulnar head
How many and which tendons are enclosed in the common flexor sheath?
4 tendons from FDS and 4 from FDP
Can FDS flex each finger independently?
Yes
Where is the neurovascular plane in the anterior forearm?
It is the fascial plane that lies between the intermediate and deep layers of muscle.
The only muscle able to flex the DIPJs is….
FDP
The tendons of FDP are ___ to the tendons of FDS in the Carpal Tunnel
Posterior
Which DIPJs are able to be flexed independently
Only the index finger DIPj due to the part of FDP supplying this digit branching off from the rest of FDP early in the forearm. c/w FDS which can flex all the PIPjs independently.
FPL muslce lies ___ to FDP in the forearm. And distal to the ____ muscle
Lateral to FDP and distal to Supinator
FPL overlies the ___ bone in the forearm while FDP overlies the ___ bone
FPL - radius. FDP - ulnar
The FPL tendon course in the wrist….
Passes through the carpal tunnel enclosed in its own tendinous sheath
What landmarks demarcate the anterior and posterior compartments of the forearm
The radial artery laterally and the sharp, subcutaneous posterior boarder of the ulnar medially
The structures that pass through the carpal tunnel are…
9 tendons - FPL, 4 from FDP and 4 from FDS
1 nerve - median nerve
the FPL tendon pass through the carpal tunnel on the ___ side of the FDS and FDP tendons
Lateral
Which is the only muscle able to flex the IPJ of the thumb
FPL - median n
The deepest muscle in the anterior forearm is…
Pronator Quadratus
The muscle that is most important for pronation is ___ due to its role in initiating the movment
Pronator Quadratus. Pronator Teres assists when more speed and power is required.
Structures holding the radius and ulnar together distally during force transmitted through the wrist…
interosseus membrane. Pronator Quadratus
The common flexor attachment is…
Medical epicondyle and supracondylar ridge of humerus.
Muscles that extend and abduct or adduct the hand at the wrist joint (Extensor group 1)
ECRL, ECRB, ECU
Muscles that extend the medial 4 fingers (Extensor group 2)
Extensor Digitorum, Extensor Indicies, Extensor digiti minimi
Muscles that extend or abduct the thumb (Extensor group 3)
Abductor Pollicus Longus
Extensor Pollicus Brevis
Extensor Pollicus Longus
The extensor tendons are held in place at the wrist by ….
the extensor retinaculum.
The common extensor tendon of the forearm is…
attached to the lateral epicondyle of humerus
Brachioradialis and ECRL attach
lateral supracondylar ridge of humerus and adjacent lateral intermuscular septum
FDS has _ proximal attachements and they are ___
- radius, ulnar and humerus
the most medial and lateral tendons of ED are joined on their sides by which two tenons near the MCPJS passing down the posterior aspect of the digits.
EI and EDM
An important flexor of the forearm, active in quick movements or in the presence of resistance is….
Brachioradialis
The muscle that resists subluxation of the head of the radius is….
Brachioradialis
the two forearm extensors that do NOT cross the wrist are…
Supinator and Brachioradialis
The three” outcropping muscles of the thumb” are…
APL, EPB, EPL
The outcropping muscles of the thumb come out from between which two muscles?
ECRB and ED
Which muscles are indispensible when clenching the fist?
ECRL, ECU
distal attachment of ECRB
base of 3rd MC dorsally
distal attachement of ECRL
base of 2nd MC dorsally
the ECRL and ECRB pass under the extensor retinaculum in which sheath?
the tendinous sheath of the extensor carpi radiales
which tendon passes under the retinaculum in the same sheath as ED
EI
The ___ ___ restrict independent extension of the digits through linking the tendons of ___ ___ proximal to the ____ joints
intertendinous connections, ED, MCPjs
extensor expansions are flattened extensions of which muscle’s tendons
ED
Where do the extensor expansions attach?
the sides of the MC head and the proximal phalanx
The medial bands of the extensor expansions attach to…..
the middle phalanges
The lateral bands of the extensor expansions attach to…
the distal phalanges
the tendons of the interosseus and lumbrical muscles of the hand join the ____ bands of the extensor expansions
Lateral bands
the _____ ______ joins the extensor expansion to the distal phalanx
the retinacular ligament is a delicate fibrous band that runs from the proximal phalanx and fibrous digital sheath obliquely across the middle phalanx and two interphalangeal joints
ECU proximal attachements (2 heads)
- humeral head - common extensor tendon
- ulnar head - from a common aponeurosis attached to the posterior boarder of the ulna and shared with FCU and FDP and the deep forearm fascia.
Distal course of ECU
Runs in its own tendinous sheath in a groove between the ulnar head and its styloid process through a separate compartment of the extensor retinaculum.
The deep branch of the ____ nerve passes between the the fibres of the supinator, separating them into deep and superficial layers
Deep branch of Radial n
the deep branch of the _____ nerve becomes the _______ after passing through the ______ muscle into the posterior compartment of the forearm
Deep branch of radial nerve becomes the posterior interosseus n after passing posteriorly through the supinator muscle where it joins the posterior interosseus artery.
slow unopposed supination performed by…
Supinator
Rapid and forceful supination performed by…
biceps brachii
APL attaches to what distally?
often splits into two distal attachments - base of 1st MC and trapezium
what two posterior muscles acting on the thumb share a tendinous sheath that passes under the extensor retinaculum
APL and EPB
Which tendons make up the anatomical snuff box?
APL -most lateral
EPB - also forms the lateral boarder
EPL - medial boarder by itself
EPB distal attachment
base of proximal phalanx of thumb
How does EPL pass into the hand
Under the extensor retinaculum in its own named synovial sheath, medial to the dorsal tubercle of the radius.
How is the EPL related to the dorsal tubercle of the radius
It passes medial to it, using it as a pulley to change its line of pull
Distal EPL attachment
Base of distal phalanx of thumb.
which artery lies in the floor of the anatomical snuff box
radial artery
which bony structures can be palpated in the anatomical snuff box
base of 1st MC. Radial styloid process. Scaphoid. Trapezium.
Which muscle belly lies adjacent/medial to EPL?
Extensor Indices
The contents of the central compartment of the palm are…
The long flexor tendons and the lumbricals
The boarder of the medial compartment of the palm is the _____ which attaches between the _____ and the ______
The medial fibrous septum, medial boarder of palmar aponeurosis, 5th MC
The boarder of the lateral compartment of the palm is the ____ whic attaches distally to…
lateral fibrous septum, lateral boarder of palmar aponeurosis to the 3rd MC
The adductor compartment in the palm is deep to…
Thenar compartment
The two “spaces” in the hand are called…. and are located….
Midpalmar space under the central compartment and the thenar space under the thenar compartment, on top of the adductor compartment
There are _ compartments in the palm and their names are
- Hypothenar compartment
- Central compartment
- Thenar compartment
- Adductor compartment
- Interosseous compartment(s)
The palmar aponeurosis is continuous with this tendon…
PL
The palmar fascia is continuous with the __________ fascia
antebrachiala fascia
The muscle that crinkles the palmar skin to increase grip is….
palmaris brevis
The thenar muscles are ….
Abductor Pollicis Brevis
Flexor Pollicis Brevis (2 heads)
Opponens Pollicis
The hypothenar muscles are…
Abductor digiti minimi brevis
Flexor digiti minimi brevis
Opponens digiti minimi
The 4 dorsal interossi have what action?
Abduction of fingers
The 3 palmar interossi have what actionn
Adduction of fingers
The lumbricals produce what action?
Extension at IPjs, Flexion at MCPjs
The claw hand deformity is due to injury to which nerve and which muscles supplied by it?
Ulnar nerve. Short muscles of hand - lumbricals and interossi
what is the tendinous chiasm
The hole created by the splitting of the FDS tendon as it attaches to both sides of the base of the middle phalanx. The tendon of FDP passes through this before attaching to the base of the distal phalanx.
the contents of Guyon’s tunnel are…
Ulnar nerve and artery
Guyon’s canal is formed by which bony structures?
pisiform and hook of hamate.
The FDS tendons are arranged how?
index and pinkie finger are deep to middle and ring finger.
The common flexor sheath contains which tendons
4 FDP and 4 FDS tendons
The annular and cruciform are parts of what?
Digital fibrous sheaths that form pulley type mechanism to prevent digital flexor tendons from bow stringing.
The tendons of ___ and ___ share a synovial sheath at the ____ boarder of the anatomical snuff box
APL and EPB at the lateral boarder
the carpal tunnel is made up of which bony structures? - where does the flexor retinaculum attach to?
the tubercles of the scaphoid and tramezium on the lateral side and the pisiform and hook of hamate on the medial side
the lumbrical muscles attach to the _____ sides of the ____
lateral sides of the extensor expansions of the 2-5th digits
The lumbricals originate from where?
FDP tendons!
Describe the structure of the lumbrical muscles and their proximal attachements.
1st and 2nd are unipenate, originating from the FDP tendons to the index and middle fingers. The 3rd and 4th lummbricals are bipenate orininating from the FDP tendons to the pinkie and ring and middle fingers
Describe the dorsal interossei
Bipenate muscles. Arise from the sides of the MCs - distal attachments are to the base of the proximal phalanges, extensor expansions of the 2-4 digits
describe the palmar interossei
3 unipenate muscles from the 2nd, 4th and 5th MCs. Attach to prox phalanges extensor expansions of 2nd, 4th and 5th digits
The distal wrist crease is a surface marker for what structre?
the proximal boarder of the flexor retinaculum
which is more proximal of the deep and the superficial palmar arterial arches?
deep is more proximal