Arm, Forearm and Hand (Week 3--Miller) Flashcards
2 compartments of the arm
Anterior compartment
Posterior compartment
Divided by brachial fascia (a deep fascia) and intermuscluar fascial septum
Anterior compartment
Flexor compartment
Muscles are BBC: biceps brachii, brachialis, coracobrachialis
Nerve: musculocutaneous nerve
Artery: brachial artery
Posterior compartment
Extensor compartment
Muscle is only triceps
Nerve: radial nerve
Artery: deep **brachial artery **
Anterior arm cutaneous veins
Cephalic vein
Basilic vein
Median cubital vein
What is so special about the basilic vein?
Used for central venous catheterization because is in direct line with axillary vein
And, from cubital fossa until vein reaches axillary vein, it increases in diameter
2 layers of anterior compartment arm muscles
1) Superficial layer: biceps brachii
2) Deep layer: brachialis and coracobrachialis
Course of the musculocutaneous nerve
Musculocutaneous nerve pierces the coracobrachialis and lies between superficial and deep layer muscles
Medial neurovascular bundle
Runs down medial aspect of arm
Contains brachial artery, brachial veins, basilic vein, median nerve, ulnar nerve, medial antebrachial cutaneous nerve
Deep brachial artery originates from brachial artery in anterior compartment then travels to posterior compartment
Median and ulnar nerves pass through anterior compartment of arm without innervating anything until they reach anterior compartment of the forearm!
3 heads of the triceps
Lateral head: attaches to posterior superior humerus (does not cross shoulder joint and therefore cannot act on it)
Long head: crosses shoulder joint (so can act on it) posteriorly and attaches to infraglenoid tubercle (below glenoid fossa!) of scapula
Medial head
Course of the radial nerve
Originates off posterior cord of brachial plexus, travels into posterior compartment of arm and courses inferiorly along with deep brachial artery in radial groove of humerus (deep to triceps)
Cubital fossa
In front of elbow (bounded by imaginary line between 2 epicondyles of the humerus (pronator teres and brachioradialis))
Superficial layers: lateral antebrachial cutaneous nerve, biceps tendon, brachial artery, median nerve
Deep layers: (between brachialis and brachioradialis) radial nerve and 2 terminal branches, superficial and deep radial nerve
Posteriorly, ulnar nerve can be palpated between olecranon process and medial epicondyle of humerus (this is what you hit when you hit your funny bone!)
Superficial layer structures of cubital fossa
Lateral antebrachial cutaneous nerve: continuation of musculocutaneous nerve after it passes biceps tendon; sensory nerve to lateral forearm
Biceps tendon
Brachial artery
Median nerve
Deep layer structures of cubital fossa
Radial nerve: deep, in between brachialis and brachioradialis; divides into two branches (deep and superficial radial nerve)
Deep radial nerve pierces supinator muscle and goes into posterior compartment of forearm
Superficial radial nerve travels deep to brachioradialis then becomes cutaneous on posterior side of hand
Ulnar nerve
Travels from anterior compartment of arm posterior to medial epicondyle of humerus then comes back into anterior compartment of forearm
Located between medial epicondyle of humerus and olecranon process of ulna
2 compartments of the forearm
Anterior compartment
Posterior compartment
Antebrachial fascia, interosseous membrane, intermuscular septa divide the compartments
Anterior compartment of forearm
Flexor compartment
Wrist and digits
Nerves: median and ulnar nerves
Arteries: radial, ulnar, anterior interosseus artery
Posterior compartment of forearm
Extensor compartment
Wrist and digits
Nerves: radial nerve (branches into posterior interosseus nerve)
Arteries: posterior interosseous artery
3 muscle layers in the anterior compartment of forearm
Superficial layer: (wrist flexor-pronator group; all attach to medial epicondyle of humerus via common flexor tendon) pronator teres, flexor carpi radialis, palmaris longus, flexor carpi ulnaris
Intermediate layer: flexor digitorum superficialis
Deep layer: flexor digitorum profundus, flexor pollicis longus, pronator quadratus
Ulnar artery
Gives rise to common interosseus artery which terminates by forming the anterior interosseus artery and posterior interosseus artery
Anterior compartment of forearm cutaneous veins
1) Classic pattern: median cubital vein connects the basilic vein and the cephalic vein
2) Cephalic vein –> median cephalic vein –> median antebrachial vein, and at the same time on other side, Basilic vein –> median basilic vein –> median antebrachial vein (converge at one median antebrachial vein)
Golfer’s Elbow
Painful MSK condition that may follow repetitive use of wrist flexor-pronator group
Pain on medial side of elbow
Repeated forceful movements strain common flexor tendon of these muscles and produce inflammation of medial epicondyle
Artery and nerve relationships of anterior compartment of forearm
Superficial radial nerve and radial artery travel together deep to the brachioradialis muscle
Brachial artery enters proximal anterior forearm and then terminates as ulnar and radial arteries
Ulnar artery gives rise to common interosseous artery which is a short artery that terminates as anterior interosseus artery and posterior interosseus artery (posterior compartment)
Ulnar artery travels with ulnar nerve between flexor digitorum superficialis and flexor digitorum profundis
Anterior interosseous artery travels with the anterior interosseus branch of the median nerve between the flexor digitorum superficialis and flexor digitorum profundis
Innervation of anterior compartment of forearm
Median nerve innervates all muscles of anterior compartment except for 1 1/2 muscles!
Median nerve branches to give off anterior interosseous nerve
Ulnar nerve innervates flexor carpi ulnaris and 1/2 flexor digitorum profundus (ulnar half)
2 muscle layers in the posterior compartment of forearm
Superficial lateral: brachioradialis, extensor carpi radialis longus, extensor carpi radialis brevis
Superficial posterior: anconeus, extensor carpi ulnaris, extensor digitorum, extensory digiti minimi
Deep: extensor pollicis longus, extensor pollicis brevis, abductor pollicis longus, extensor indicis, supinator
Posterior compartment of forearm cutaneous veins
Cephalic vein ascends lateral side of arm
Basilic vein ascends medial side of arm
Cephalic and basilic veins originate from dorsal venous arch on dorsum of hand
Tennis Elbow
Inflamation of lateral epicondyle of the humerus through repeated use
Many superficial layer muscles have attachment to lateral epicondyle of humerus via common extensor tendon
Nerves and arteries of posterior compartment of forearm
Neurovascular plane between superficial layer and deep layer muscles contains posterior interosseus nerve and posterior interosseus artery
Posterior interosseus nerve is continuation of deep radial nerve (changes names once it enters posterior compartment)
Anatomical “snuff box”
Triangular space between extensor pollicis brevis (along with abductor pollicis longus, APL), extensor pollicis longus and extensor retinaculum
Radial artery crosses floor (so pulse can be taken here)
Scaphoid bone lies in floor of snuff box and may be palpated in assessing scaphoid fracture
Course of radial artery
Radial artery crosses floor of anatomical “snuff box” then through two heads of 1st dorsal interosseus muscle and gives off princeps pollicis and radial index arteries
Extensor retinaculum
Band of deep fascia that helps keep extensor tendons in place when extensor muscles contract
Synovial tendon sheaths
Protect extensor tendons by reducing friction when tendons slide under retinaculum
(are between extensor tendons and extensor retinaculum)
Extensor expansions
Extensor tendons become flattened to form extensor expansions distally
Dorsal interossei muscles vs. palmar interossei muscles
Dorsal: seen deep to extensor tendons; only interossei muscles that can be seen on dorsum of hand; “DAB” = dorsal abducts fingers (4)
Palmar: “PAD” = palmar adducts fingers (3)
Movements of joints of the hands
Interphalangeal (IP) joints: flexion and extension
Metacarpophalangeal (MCP) joints: flexion, extension, abduction, adduction, circumduction
Carpometacarpal joints: gliding
Intercarpal (IC) joints: gliding and sliding
Carpometacarpal joint of thumb: flexion, extension, abduction, adduction, opposition
Note: movement away from 3rd digit is abduction, movement toward 3rd digit is adduction
Carpal bones proximal row from lateral to medial (palmar view)
Scaphoid
Lunate
Triquetrum (w/ Pisiform)
“So Long To Pinky…”
Carpal bones distal row from lateral to medial (palmar view)
Hamate
Capitate
Trapezoid
Trapezium
“…Here Comes The Thumb”
Wrist joint (radiocarpal joint)
Articulation between distal radius, articular disc, proximal row of carpal bones
Synovial joint that permits adduction, abduction, flexion, extension, circumduction
Distal radioulnar joint
Articulation between distal radius and ulna
NOT part of the wrist joint, but is synovial joint that acts with proximal radioulnar articulation of the elbow joint to permit abduction and supination
Structures crossing wrist anteriorly
From lateral to medial:
Radial artery
Flexor carpi radialis
Median nerve
Flexor digitorum superficialis (palmaris longus)
Ulnar artery
Ulnar nerve
Flexor carpi ulnaris
Carpal tunnel
Space between flexor retinaculum and carpal bones
Roof is flexor retinaculum; floor is carpal bones
Contains 10 structures:
4 FDS tendons (flexor digitorum superficialis)
4 FDP tendons (flexor digitorum profundis)
FPL tendon (flexor pollicis longus)
Median nerve
Tunnel of Guyon
Fascial tunnel that carries ulnar nerve and artery
(aka ulnar nerve tunnel)
Carpal Tunnel Syndrome
Inflammation within carpal tunnel compresses median nerve
Sensory effects: pain and sensory deficits (paresthesia, hypothesia, anesthesia) along distribution of its cutaneous branches which innervate 3 1/2 lateral digits of the hand
Motor effects: motor deficits to thenar compartment muscles and lateral 2 lumbrical muscles which it innervates; muscle weakness, loss of coordination, inability to oppose thumb; motor effects come AFTER sensory effects bc sensory fibers fatter
Carpal Tunnel Release: surgical division of flexor retinaculum (partially or completely) to relieve symptoms of carpal tunnel syndrome
4 compartments of the hand
1) Thenar compartment
2) Hypothenar compartment
3) Central (or midpalmar) compartment
4) Deep (adductor/interossei) compartment
Thenar compartment
3 muscles relating to the thumb:
Abductor pollicis brevis (outside)
Flexor pollicis brevis (inside)
Opponens pollicis (deep)
Hypothenar compartment
3 muscles relating to the 5th digit (pinky)
Abductor digiti minimi (outside)
Flexor digiti minimi (inside)
Opponens digiti minimi (deep and a bit lateral)
Central compartment
Flexor tendons (of FDS and FDP)
4 lumbricals attach to tendons of flexor digitorum profundis: lateral 2 lumbricals (1 and 2) innervated by median nerve; medial 2 lumbricals (3 and 4) innervated by ulnar nerve
Lumbricals flex at MCP joints and extend at IP joints
Extensor expansions: aponeurosis-like extensor tendons which form a “hood” that crosses IP joints posteriorly
Deep compartment
Adductor pollicis
Interossei muscles (palmar and dorsal):
4 Dorsal interossei abduct (“DAB”)
3 Palmar interossei adduct (“PAD”)
Palmar aponeurosis
Attaches to palmaris longus tendon
Which comes from flexor digitorum superficialis?
Motor innervation of the hand
Most muscles innervated by ulnar nerve, except for 1 1/2 compartments!
Thenar compartment and lateral 2 lumbricals innervated by median nerve
Overview of blood supply to upper limb
Brachial artery gives rise to radial and ulnar artery in forearm
These pass into the hand to form superficial (mostly from ulnar artery) and deep palmar (mostly from radial artery) arches
The arches give rise to common palmar digital arteries (related to metacarpals) which then give rise to proper palmar arteries (related to digits)
Cutaneous nerve pattern
Supraclavicular nerves
Axillary nerve
Radial nerve
Musculocutaneous nerve
Superficial radial nerve
Median nerve
Ulnar nerve
Medial antebrachial cutaneous nerve
Intercostobrachial nerve and Medial brachial cutaneous nerve
Dermatomal pattern of upper limb
From side of head/neck all the way down to fingers
C2-T1
Why is the cutaneous nerve innervation pattern different from the dermatomal pattern of innervation?
A dermatome is a strip of skin innervated by fibers from a single spinal cord level but a cutaneous nerve contains fibers from several spinal cord levels!
