Upper Limb Session 3 and 4 Flashcards
What are the functions of the muscles of the anterior forearm?
Flexors of the wrist and the pronators of the forearm
How are the muscles of the anterior forearm arranged into groups?
Superficial, intermediate and deep groups
Outline the muscles of the superficial group of anterior forearm muscles
Pronator teres
Flexor carpi radialis
Palmaris longus
Flexor carpi ulnaris
What is the common attachment for the superficial muscles of the anterior forearm?
Common flexor tendon attaching to the medial chondyl of the humerus
What is the innervation of the superficial group muscles of the anterior forearm?
Median nerve (expect for FCU which is supplied by the ulnar nerve)
Organise the superficial muscles of the anterior forearm from lateral to medial
Most lateral - pronator teres
FCR
PL
Most medial - FCU
Outline the course of the FCU
Attached to the pisiform carpal bone and causes flexion and adduction of the wrist
Outline the course of the PL
Attaches to the flexor retinaculum of the wrist and causes flexion
Outline the course of the FCR
Attaches to the base of metacarpals II and III and causes flexion and abduction at the wrist
Outline the course of the PT
Two origins; common flexor origin and also the coronoid process of the ulnar
Attaches to the mid shaft of the radius and pronates the forearm
Outline the muscles of the intermediate group of anterior forearm muscles
The flexor digitorum superficially is the only muscle in this group
Outline the course of the FDS
It has two heads - one on the medial epichondyle and another from the radius
What structures run between the two heads of the FDS?
Median nerve and ulnar artery pass between these heads and travel posteriorly
How does the FDS terminate?
The muscle splits into four tendons at the west and travel through the carpal tunnel and attach to the middle phalanx of each of the four digits
Outline the muscles of the deep group of anterior forearm muscles
Flexor digitorum profundus
Flexor pollicis longus
Pronator quadratura
What is the course of the FDP?
Originates from the ulnar and interosseous membrane it splits into four tendons and passes through the carpal tunnel to attach to the distal phalanges of each of the four fingers
What is the innervations of the FDP?
Median nerve (interosseous branch) and the ulnar nerve
What is the course of the FPL?
Originates from the anterior surface of the radius and interosseous membrane and attaches to the base of the distal phalanx of the thumb
What is the innervations of the FDP?
Median nerve (interosseous branch)
What is the course of the PQ?
A square sheet of muscle found deep to the tendons of the FDP and FPL
Originates on the anterior surface of the ulna and inserts to the anterior surface of the radius
What is the innervations of the PQ?
Median nerve (interosseous branch)
What is the main nerve of the anterior forearm?
Median nerve
What is the course of the median nerve in the forearm?
Runs between the FDS and the FDP
Enters the hand via the carpal tunnel
What does the median nerve innervate?
Lateral three digits, thenar muscles and the lateral two lumbricals
After passing posterior to the medial epichondyl, what is the course of the ulnar nerve?
Passes between the heads of the FCU
What is the carpal tunnel?
A passageway deep to the flexor retinaculum between the scaphoid and the trapezium on the lateral side and the pisiform and the hamate bone on the medial side
What are the contents of the carpal tunnel?
- Median nerve
- Four tendons of the FDS
- Four tendons of the FDP
- One tendon from the FPL
What ligamentous structure runs immediately superficially to the flexor retinaculum?
Palmar aponeurosis
What is the palmar aponeurosis?
A continuation of the palmaris longus muscle
The intrinsic muscles of the hand are ordered into five compartments, what are they?
- Thenar
- Hypothenar
- Adductor
- Lumbricals and long flexor tendon - central compartment
- Interosseous
What palpable structure do the muscles of the thenar compartment form?
The thenar eminence on the lateral portion the hand
What muscles are in the thenar compartment and what is their innervation?
- Aductor pollicis brevis
- Flexor pollicis brevis
- Opponens pollicis
Median nerve (C8-T1)
What palpable structure do the muscles of the hypothenar compartment form?
Hypothenar eminence on the medial side of the palm
What are the muscles of the hypothenar compartment?
Aductor digiti minimi
Flexor digiti minimi
Opponens digiti minimi
What muscle is contained in the adductor compartment of the hand?
Adductor pollicis
Describe the structure of the adductor pollicis
Has both a superior transverse and and inferior oblique head
What is the innervation of the adductor compartment?
Deep branch of the ulnar nerve
What muscles are located in the central compartment of the hand?
Four Lumbricals
What is the course of the lumbricals?
They originate from the flexor tendon of the flexor digitorum profundus and attach to each digit
What is the action of the lumbricals?
Flex the fingers at the MCP joints and simultaneously extend the inter-phalangeal joints
How are the lumbricals innervated?
Medial two - median nerve
Lateral two - ulnar nerve
Which of the lumbricals are unipennate and which are bipennate?
LI and LII are unipennate
LIII and LIV - bipennate
What muscles are present in the interosseous compartment?
Muscles between the metacarpal bones (interossei)
There are four dorsal and three palmar
Which interossei adduct and which abduct?
Hint: DAB PAD
Dorsal abduct and Palmar adduct
How are the interossei innervated?
By the deep branch of the ulnar nerve
Which arteries provide blood to the hand?
Ulnar and radial artery
What structures do the arteries of the hand form?
Superficial and deep palmar arches giving rise to common digital arteries
What type of joint is the wrist joint?
Synovial chondyloid
What bone are involved in the radio-carpal joint?
Distal radius and the articular surfaces of the proximal carpal bones
Name the eight carpal bones
Scaphoid Lunate Hamate Pisiform Capitate Trapezoid Trapezium Triquentrum
Name the proximal row of carpal bones from lateral to medial
Scaphoid, lunate, triquetrum, pisiform
Name the distal row of carpal bones from lateral to medial
Trapezium
Trapezoid
Capitate
Hamate
What muscles facilitate flexion at the wrist?
Anterior compartment of the forearm
What muscles facilitate extension at the wrist?
Posterior compartment of the forearm
What muscles facilitate ulnar deviation (adduction) at the wrist?
Flexor and extensor carpi ulnaris
What muscles facilitate radial deviation (abduction) at the wrist?
Abductor pollicis longus and brevis, flexor carpi radials and extensor carpi radialis
What muscles facilitate circumflexion at the wrist?
A complex interaction of multiple compartments of the forearm
How are muscles of the posterior forearm arranged?
Into three functional groups
- Muscles that extend abduct/adduct the hand at the wrist
- Muscles that extend the medial four digits
- Muscles that extend or abduct the thumb
What muscles act on the wrist joint from the posterior compartment of the forearm?
Extensor carpi radialis longus and brevis extend and abduct the wrist joint
With the help of the FCR these muscles also allow for radial deviation
What muscles extend the medial four digits from the posterior compartment of the forearm?
- Extensor digitorum
- Extensor indicies (deep muscle)
- Extensor digiti minimi
What is the course of the ED muscle?
Arises from the common extensor origin of the lateral epicondyle
Ends in a tendon and passes under the extensor retinaculum and further divides into finger tendons
What muscles extend or abduct the thumb?
- Abductor pollicis longus
- Extensor pollicis brevis
- Extensor pollicis longus
What nerve innervates all muscles of the posterior arm?
Radial nerve
What muscle envelopes the neck and the proximal part of the shaft of the radius?
Supinator
What nerve supplies the supinator muscle?
Radial nerve (deep branch - also called the posterior interosseous nerve)
What is the function of the superficial branch of the radial nerve?
Sensory and distributed to skin on the dorsum of the hand
What is the anatomical snuffbox?
A shallow depression on the lateral aspect of the wrist when the thumb is extended fully
Describe the borders of the anatomical snuffbox
Medial border - tendon of the extensor pollicis longus
Lateral border - tendons of the abductor pollicis longus and extensor pollicus brevis
Proximal border - styloid process of the radius
Floor - scaphoid and trapezoid carpal bones
Roof - skin
What are the contents of the anatomical snuffbox?
Superficial branch of the radial nerve, cephalic vein and the radial artery
What nerve innervates the EPL, EPB and the APL?
Posterior interosseous nerve
What are the main actions of the EPB and the EPL?
EPB - extension
EPL - hyperextension
What is the extensor expansion?
Also called dorsal digital expansion - comprised of four extensor digitorum tendons which flatten
Each expansion is a triangular tendinous aponeurosis that wraps arounds the dorsal and sides of the head of the metacarpal and base of the proximal phalanx