Upper Limb Flashcards
what are the two essential functions of the brachial plexus?
supplies motor & sensory innervation to shoulder and arm
How is a nerve plexus formed?
Nerve fibres from two or more spinal segments intermingle then segregate to travel together to a common anatomical region
where do the brachial plexus nerves originate from in the spinal cord, what section?
C5-T1
what is the path of the fibres from spinal cord to target?
Roots, trunks, divisions, cords, terminal branches
how many roots are there and their origin from spinal cord?
5,
C5, C6, C7, C8, T1
how are the three trunks formed?
C5 and C6 = superior trunk
C7 = middle trunk
C8 and T1 = inferior trunk
how many divisions are there and what are they called?
6 divisions
2 for each trunk
Anterior and posterior for each trunk
how many cords are there and their names and why
3
lateral, posterior, medial
named according to position relative to axillary artery
how each cord is formed:
lateral = from both anterior divisons from upper and middle trunk
posterior = from all three posterior divisions
medial = from anterior division from lower trunk
what are the 5 terminal branches of the brachial plexus
musculocutaneous nerve
axillary nerve
radial nerve
median nerve
ulnar nerve
how is each terminal branch formed (from what cord)
musculocutaneous = lateral cord
axillary = posterior cord
radial = posterior cord
median = lateral and medial cord
ulnar = medial cord
what is a good reference point of the brachial plexus
the M characteristic formed by terminal branches of lateral and medial cords
C5 & C5, C6, C7
what branches arise from the brachial plexus roots? (2)
Dorsal scapular nerve - C5
long thoracic nerve - C5, C6, C7
both come from upper trunk
what branches arise from the brachial plexus trunk? (2)
Suprascapular nerve = upper trunk
Nerve to subclavius = upper trunk
what nerves arise from the brachial plexus divisions?
No nerves!
lateral cord = 1, posterior cord = 3, medial cord = 3
what nerves arise from the brachial plexus cords? (7)
Lateral cord = lateral pectoral nerve
posterior cord = upper, middle and lower subscapular nerve
medial cord = medial pectoral nerve, medial brachial cutaneous nerve, medial antebrachial cutaneous nerve
what happens when you fall on your head?
how can upper brachial plexus injury occur?
extreme lateral flexion of head, especially when shoulder is depressed
what does upper brachial plexus injury result in:
Erb-Duchenne Paralysis
what are characteristics of Erb-Duchenne Paralysis (3)
arm hangs limp at side
internally rotated
forearm also pronated
clinging on something with one arm when falling from somewhere
how can lower brachial plexus injury usually occur?
extreme abduction of the upper arm
what does lower brachial plexus injury usually effect in terms of spinal cord segments
C8 and T1
what does lower brachial plexus injury usually result in?
Klumpke’s Paralysis
what are characteristics of Klumpke’s paralysis
a “claw hand”, fingers are flexed in claw position
what are the two sensory signs of nerve injury
Loss of sensation
Paraesthesia
what is paraesthesia?
tingling, burning, or pins and needles sensation
terminal branches of brachial plexus, one other
what are frequently injured nerves located around the shoulder and arm region (6 nerves)
Long thoracic nerve
the 5 terminal branches of the brachial plexus:
axillary
radial
musculocutaneous
ulnar
median
where is the long thoracic nerve found, & what is supplies?
travels inferiorly on lateral chest wall to supply innervation to serratus anterior muscle
why is the long thoracic nerve easily injured? (2)
- located on superficial surface of muscle
- covered only by skin and subcutaneous fat
what is the classic sign of thoracic nerve injury?
winging of the scapula
how is winging of the scapula tested? (2)
patient supports weight with hands while leaning on wall
if injured, medialy boarder of scapula will make obvious dorsal protrusion
stability of scapula muscle
why does injury of the long thoracic nerve cause winging of the scapula? (2)
The nerve innervates the Serratus anterior
this muscle is crucial for movement and stability of the scapula.
process involves removal of one or both breasts
what type of operation typically causes long thoracic nerve injury?
Mastectomy:
surgical procedure involving removal of one or both breasts usually due to cancer
what is the axillary nerve a terminal branch of?
the posterior cord
innervates deltoid and teres minor muscles
square type space
location of the axillary nerve: (3)
travels posterior through quadrangular space in shoulder
around surgical neck of humerus
what is the surgical neck of the humerus? (1)
the narrow part just below the humeral head
what is the motor innervation of the axillary nerve? (2)
Deltoid
Teres Minor
what is the sensory innervation of the axillary nerve? (1)
patch of skin over lateral-posterior shoulder
Typical causes of axillary nerve injury: (2)
Fracture of upper neck of humerus
shoulder dislocation
what does axillary nerve injury result in terms of motor control? (3) which muscle causes this?
loss of shoulder abduction above 15 degrees (deltoid)
weakened external rotation of humerus (teres minor)
weakened stability of shoulder joint (Teres minor)
what is the sensory effect of axillary nerve injury? (1)
loss of sensation over posterior-lateral aspect of shoulder
what is the radial nerve a terminal branch of?
posterior cord
path of radial nerve: (5)
travels posterior around body of humerus
lies in radial groove
just distal to elbow joint, divides into many branches
extends all the way to lateral aspect of hand
what is the radial groove of the humerus? (2)
a shallow groove on the posterior aspect of the humerus
serves as a pathway for radial nerve
what is the motor innervation of the radial nerve? (3)
all extensor compartment muscles of arm and forearm
brachioradialis
supinator muscle
where is the brachioradilais muscle found (1) and what does it do? (3)
found on lateral side of forearm
flexion and extension of forearm
assist in flexion of elbow
what is the sensory innervation of the radial nerve?
skin on dorsal surface (tricep side) of all arm and hand
what is the name of the extension of the radial nerve that supplies the brachioradialis
Posterior interosseus nerve (PIN)
what are characteristics of radial nerve injury? (2)
wrist drop due to loss of extensor muscles in forearm
loss of elbow extension
what causes radial nerve injury? (2)
fracture of middle of humerus
nerve compression
how can the radial nerve be compressed? (2)
crutches
sleeping with companions head resting on arm
which cord?
what is the musculocutaneous nerve a terminal branch of?
lateral cord
3 muscles in flexor compartment of upper arm
what does the musculocutaneous nerve provide motor innervation to?
coracobrachialis
brachialis
biceps brachii
what does the musculocutaneous nerve provide sensory innervation to?
lateral forearm
the specific branch of this nerve is called the antebrachial/lateral cutaneous nerve
has two names
what is the branch of the musculocutaneous nerve that supplies the lateral aspect of forearm
antebrachial/ lateral cutaneous nerve
what does damage to the musculocutaneous nerve result in (motor)? (2)
loss of elbow flexion
weakened elbow supination
which cord
what is the ulnar nerve a terminal branch of?
Medial cord
what does the ulnar nerve innervate in the upper arm?
no structures!
only muscles
what does the ulnar nerve innervate in forearm? (2)
flexor carpi ulnaris muscle
1/2 flexor digitorum profundus muscle
where is the flexor carpi ulnaris muscle found?
medial side of forearm
involved in hand movement
what does the flexor carpi ulnaris muscle do? (2)
flex & adduct hand at wrist joint
how middle is it in forearm?
where is the flexor digitorum profundus muscle found? (2)
deep layer of anterior compartment of forearm
medial in forearm, but slightly on side of ulna
important in rock climbing!
what does the flexor digitorum profundus muscle do? (1)
flexing the distal phalanges of the fingers - all fingers
I have injured it section of it
passage of the ulnar nerve (4)
travels medial to humerus
passes through cubital tunnel
runs medial in forearm
terminates in medial aspect of hand
i have injured it!
what is the cubital tunnel?
what bones form it, what tissue covers it, what nerve travels through
a tunnel formed by the medial epicondyle of the humerus & the olecranon process of the ulna.
reinforced by a fibrous band of connective tissue called cubital retinacululm
the ulna nerve passes through here
what is the sensory innervation of the ulnar nerve? (3)
medial 1/3 of hand, pinky and ring finger
how is the ulnar nerve commonly injured? (2)
entrapment as is passes medial lower end of humerus
fracture of lower end of medial humerus
what does injury of the ulnar nerve cause?
Tardy Ulnar Palsy
Claw hand - in ring and pinky finger
what is tardy Ulnar palsy? (2)
Paraesthesia of ring and pinky finger
los of fine motor control of these digits
is the middle “M” characteristic
what is the median nerve a terminal branch of?
medial and lateral cord
which structures in the upper arm does the medial nerve supply?
none!
passage of the median nerve (3)
medial to humerus
crosses to lateral side at lower end of humerus
gives off two nerve branches here
what two nerve branches does the median nerve give off?
Anterior interosseus nerve (AIN)
Median nerve proper
motor innervation to deep forearm muscles
what does the Anterior interosseus nerve (AIN) do? (3)
motor innervation to three muscles of forearm:
1. flexor pollicis longus
2. lateral half of flexor digitorum profundus
3. pronator quadratus
what does the flexor pollicis longus do? (1)
flexes thumb at interphalangeal joint (knuckle joint)
hints in the name!
what does the pronator quadratus do? (1)
pronates forearm
is a branch of the median nerve. 3 muscles in forearm, 2 in hand
what muscles does the median nerve proper innervate ?
forearm muscles:
* pronator teres
* Flexor carpi radialis
* palmaris longus
hand muscles:
* Thenar muscles
* lumbricals
hint is in the name
what does pronator teres do?
assists in pronates forearm
radialis!
what does flexor carpi radialis do? (2)
flexs and abducts hand at wrist joint
hint is in name - palm
what does the palmaris longus do? (1)
aids in flexion of hand at wrist
what is the sensory innervation of the median nerve proper (4)
palmar aspect of:
1. thumb
2. index finger
3. middle finger
4. lateral aspect of ring finger
what is median nerve injury mostly associated with? (1)
carpal tunnel syndrome
wht is carpal tunnel syndrome? (2)
the medial nerve is entrapped as it enters wrist under transverse carpal ligament
causes pararesthesia and pain along sensory innervation of medial nerve
think about passage of each terminal branch of brachial plexus
what 4 nerves surround the axillary artery as it emerges from beneath pectoralis minor
musculocutaneous
median
ulnar
radial
what nerves supply flexor and pronator muscles in the forearm? (2)
ulnar nerve
median nerve
what are the compartments and what they do?
how are the muscles of the upper arm arranged?
posterior compartment = extensor
anterior compartment = flexor
what is the name of the barrier between anterior and posterior compartments of upper arm, and what is it?
**intermuscular setpum:
** fibrous barrier that separates different muscle compartments within arm *
BBC
what are the three anterior muscles of the upper arm?
Biceps Brachii
Brachialis
Coracobrachialis
What are the two heads of the Biceps Brachii and there position relative to each other:
Long head - more lateral
Short head - medial
origin and insertion of both heads of biceps brachii:
Short head:
* origin = coracoid process of scapula
Long head:
* origin = supraglenoid tubercle of scapula
common insertion = radial tuberosity
Coracobrachialis origin and insertion
origin = coracoid process
insertion = midshaft of anterior humerus
coracobrachialis function (1)
weak adductor of the arm
brachialis origin and insertion
origin = distal part of anterior humerus
insertion = ulna tuberosity and ulnar coracoid process
function of the brachialis (1)
elbow flexion
Why is the Biceps Brachii a supinator of the forearm as well? (1)
due to its tendon attachment along back of radial tuberosity
what nerve supplies anterior muscles in upper arm
musculocutaneous nerve
what are the three sets of muscles invovled in movement of the arm
- flexion and extension of elbow
- pronation and supination of forearm
- flexion and extension of wrist
where do the brachial plexus divisions occur within the body
approx lower neck to axilla region
what are the superficial veins of the arm and where are they found (3)
- cephalic vein = most lateral upper arm
- Basilic vein = most medial on upper arm
- Median cubital vein = located going from medial to lateral across anterior elbow hinge. joins basilic and cephalic vein
answer is in order from most lateral to medial
what are the 4 superficial anterior muscles of the forearm?
Pronator Teres
Flexor Carpi radialis
Palmaris Longus
Flexor Carpi Ulnaris
what is the common flexor attachment of all 4 flexor muscles of the forearm?
Medial epicondyle of the humerus
origin and insertion of pronator teres
origin = medial epicondyle of humerus & proximal ulna
insertion = midshaft of radius, lateral side
function of pronator teres (1)
pronation of forearm
where does the word teres come from? what does it mean
refers to shape of muscle in cross section - “round”
Flexor Carpi radialis origin and insertion
origin = medial epicondyle of humerus
insertion = second and third metacarpal
function of flexor carpi radialis (2)
flexes wrist
Wrist abduction
how name of FCR helps in function and location (3)
Flexor - flexes
Carpi - inserts onto metacarpals
Radialis - location on radial side
Palmaris Longus origin and insertion
origin - medial epicondyle of humerus
insertion - palmar aponeurosis
what is the palmar aponeurosis & location
thick dense layer of fibrous tissue
located in the palm of the hand
what is the palmar aponeruosis a continuation of?
the antebrachial fascia
what is the function of Palmar Longus (1)
Weak wrist flexion
presence of PL in population
absent in 10-15% of population!
Flexor Carpi Ulnaris origin and insertion
Origin - Medial epicondyle of humerus
Insertion - Pisiform Carpal bone
function of Flexor Carpi radialis (2)
wrist flexion
wrist adduction
what are the intermidate (level of deepness) anterior muscles of the forearm
Flexor digitorum superficialis (FDS)
2 heads
origin of the flexor digitorum superficialis
medial epicondyle of humerus
radial head
where does the division of the FDS occur, and how many segments does it split into?
Mid forearm
4 segments - one for each finger
attachment of FDS:
middle phalanges of each finger
function of FDS (2)
wrist flexion
flexion of fingers
Brachioradialis origin and insertion
origin - lateral supracondylar ridge of humerus
insertion - styloid process of radius
function of the brachioradialis muscle (2)
flex arm at elbow joint
stabiliation of elbow joint when strong grip is required
in order from most deep to most superficial
what are the 3 deep muscles of the anterior forearm?
Pronator quadratus
Flexor pollicus Longus
Flexor Digitorum profundus
what is the interosseous membrane? (2)
- fibrous connective tissue structure located between ulna and radius
- spans length of forearm
what is the role of the interosseous membrane (2)
- provides stability and support to forearm by maintaining appropriate spatial relationhip betwen radius and ulna
- important for attachments of deep flexor muscles
pronator quadratus origin and insertion
origin - anteriomedial aspect of ulna
insertion - anterior surface of radius
function of pronator quadratus (1)
pronation of forearm
flexor pollicis longus origin and insertion
origin - midshaft of radius
insertion - distal phalanges thumb
function of flexor pollicis longus (1)
flexes thumb at interphalangeal joint
flexor digitorum profundus origin and insertion
origin - proximal ulna
attachment - distal phalanges of 4 fingers
innervation of the 3 deep flexor muscles of the forearm:
PQ - median nerve (AIN)
Flexor pollicis longus - median nerve (AIN)
flexor digitorum profundus - median nerve (AIN) and ulnar nerve
which fingers are innervated by which nerve
flexor digitorum profundus nerve innervation:
AIN nerve - index and midle finger
Ulnar nerve - ring and pinky finger
what are the 3 extensor muscles of the forearm
Extensor carpi radialis longus
Extensor carpi radialis brevis
Extensor carpi ulnaris
what is the name of the origin that is shared between the extensor muscles of the forearm?
lateral epicondyle of the humerus
extensor carpi radialis & Brevis origin and insertion
origin - lateral epicondyle of the humerus
insertion - 2nd and 3rd metacarpals
origin & insertion of the extensor carpi ulnaris
origin - lateral epicondyle of humerus & medial side of ulna
insertion - 5th metacarpal
what do all 3 extensor muscles of wrist pass under as they enter the wrist?
- extensor retinaculum
what does the extensor retinaculum act as for the extensor muscles of the forearm
a pulley
how many muscles produce pronation and what are they?
2:
pronator teres
pronator quadratus
how many muscles produce supination and what are they
2:
supinator
biceps
origin (3) and insertion of supinator muscle
origin - lateral epicondyle, annular ligament, and supinator crest of ulna
insertion - radius
what is the “parallel” muscle of pronator teres
Supinator muscle - due to very similar length, insertion and origin just on opposite sides of arm
what branch (nerve) runs through the supinator muscle
radial nerve (PIN)
how many muscles produce flexion of the fingers, and what are they?
2
* flexor digitorum profundus
* flexor digitorum superficialis
what is the deepest finger flexor
flexor digitorum profundus
what type of muscles are the muscles that flex the fingers? (1)
long muscles
what are the tendons called that arise from each muscle to attach to the fingers- frmo both finger flexing muscles)
profundus tendon
superficialis tendon