Arms Flashcards
what divisons of trunks form lateral cord of branchial plexus?
Anterior Upper
Anterior Middle
deep palmar arch
main contribution from raidal artery and help from ulnar
function of serratus anterior
Serratus anterior wraps around from the back of the scapula to rib cage in the front
elevates the rib cage when inhaling
keeps the scapula down and closely attached to the rib cage
wrist drop
When you get a radial nerve lesion, you get something called wrist drop. Why do you think the wrist would drop?
What muscles would help you extend the wrist? Extensor carpi ulnaris [and] extensor carpi radialis, longus and brevis. That’s it.
If you have your radial nerve lacerated in some way, those muscles won’t work, so you get what’s called wrist drop. There’s a similar condition for the lower limb called foot drop, which you’ll learn about that later.
acromion
on the scapula
articulates with clavicle
palmar cutaneous branch of the medial nerve
- Another point that will become important later: Palmar cutaneous branch of median nerve is important. This shiny white thing (red box) is the top of the carpal tunnel. The carpal tunnel sits directly beneath this. The median nerve travels through the carpal tunnel, but it gives off the palmar branch (a sensory branch) right before it does so.
- Even if you suspect a problem with carpal tunnel, the palmar branch of the nerve should still be working. The median nerve is working as it enters the carpal tunnel, and the problem occurs in the carpal tunnel. Distal to that, everything is out. However, the palmar branch should work, and therefore the patient should have sensation in the palm of their hand.
sensory and motor findings of ulnar nerve compression
- The ulnar nerve comes down through Guyon’s canal. The ulnar nerve has a deep branch and a superficial branch.
- Bothering the superficial branch will cause sensory deficits.
- Bothering only the deep branch will end up with claw hand.
- The key to ulnar neuropathies is to remember that the ulnar nerve does all of the interossei muscles as well as the two lumbricles. The key is that the joint between the metacarpal and the first phalanges is hyper extended (the lumbricals and interossei are not working). The extensors are unopposed.
branches of the third part of the axillary artery
subscapular
- thoracodorsal* - lat (w thoracodorsal nerve)
- scapular circumflex -* scapular circumflex - muscles on back of scapula
anterior humeral circumflex - around front of humerus
posterior humeral circumflex - around back of humerus, travels with axillary nerve, bigger
litle leaguer’s shoulder
tear in laburm in kids
can cause a fracture in the growth plate that will decrease the size of the limb
what is the triangular space
circumflex scapular artery deep to it
between teres minor and major and the other side of the triceps
muscles in the anterior compartment of the arm
flexors (and some others)
biceps - suppinate, Biceps means two heads. The long head looks shorter. The reason that it looks shorter is because its tendon disappears underneath the joint capsule. It actually extends a tiny bit higher than the short head. The short head of the biceps is attached to the coracoid process. The long head goes just above there to the top of the glenoid fossa. We’re talking millimeters, but that’s why the long head is the long head. In the lab you can’t rely on appearances. The long head is more lateral. The short head is more medial.
coracobrachialis - coracobrachialis flexes the shoulder joint not the elbow. How do you flex your shoulder joint? Not this way. This is abduction. Picking it up this way. This is flexing the shoulder. Ok so coracobrachialis flexes the shoulder. It also is a little bit of an adductor. You can see that there is a nerve piercing the coracobrachialis. This is the musculocutaneous nerve and it supplies coracobrachialis and biceps
brachialis - most powerful flexor of the elbow
what does the ulnar nerve supply?
deep compartment: medial half of flexor digitorum profundus
superficial: flexor carpi ulnaris
what spinal levels form middle trunk of brachial plexus?
C7 only
branches of the first part of the axillary artery
supreme thoracic artery - thorax wall and muscles of rib cage
carpal tunnel syndrome
each tendon has a sheath with sinovial fluid - wear it out –> inflammation –> compress median nerve
innervation of lumbricals
- The lumbricals have dual innervation.
- 2 lumbrical toward the thumb – median nerve innervation
- 2 lumbricals on the ulnar side – ulnar nerve innervation
- So, in the hand, the median nerve innervates the two lumbrical muscles and the thenar eminence muscles. All other hand muscles are innervated by the ulnar nerve.
recurrent branch of the median
- I want to mention once more about the recurrent branch of the median nerve.
- We talked about how the median nerve comes through the carpal tunnel. Once it’s into the center of the hand, it will send a recurrent branch. It curves back—this recurrent branch of the median nerve is going to turn around and come back.
- It is responsible for muscles that make up the thenar eminence.
- As you can see, it’s extremely superficial. It’s one of the most commonly injured nerves when you cut bagels. You should never cut bagel with the bagel on your hand!
- A very common injury on Sunday mornings in NYC!
It is also called the million-dollar nerve. If you cut it and cannot fix it, you lose most of the functions of your thumb
what nerves at risk for a distal humeral fracture?
. The distal humerus down by the epicondyles would be median nerve and towards the medial epicondyle would be the lateral nerve that would break.
branches of the second part of the axillary artery
thoracoacromial - short artery with a lot of branches (pectoral branches)
lateral thoracic - wall of thorax
where does the ulna hinge on the humerus?
- Trochlea: projection, medially
- Ulna (longer forearm bone): hinges on the trochlea
- Olecranon: Uppermost point of Ulna (“pointy part of your elbow”)
where does shoulder go when dislocated?
•When the shoulder is dislocated, it moves inferiorly and anteriorly due to the location of the acromion and coracoid process above the shoulder
muscles and ligaments around capsule old it in place
what function(s) of the thumb should be unaffected by a median nerve issue?
- What muscle in the thumb is working? The aDductor should be working because the aDductor is innervated by the ulnar nerve.
- If the guy has carpal tunnel, you worry about the median nerve. First thing to do is test the aDductor by seeing if patient can grab a piece of paper. (they should be able to have strength)
extensors of the wrist?
extensor carpi ulnaris
extensor carpi radialis longus
extensor carpi radialis brevis
what attaches on the ulnar tuberosity?
brachialis muscle
Spinal levels of long thoracic nerve?
C5, C6, C7
to serratus anterior - NOT from plexus
Before any fusing or splitting happens a piece of C5, C6, and C7 all come together to form that long thoracic nerve or nerve to serratus anterior. It just runs straight down into the chest it doesn’t go into the arm at all
what attaches on the radial tuberosity?
biceps brachii muscle
nere branches of the medial cord
medial pectoral - pectoralis
medial cutaneous nerve of arm - skin
medial cutaneous nerve of forearm - skin
ulnar nerve - pinky side of the medial side to fingers
medial head of the median nerve - combines with lateral heald of the median nerve
ulnar tunnel
ulnar nerve and artery
more superficial to carpal tunnel
by the pisiform bone and lies atop the flexor retinaculum
palmar arches
deep and superficial
provide anastamoses between the ulnar and radial arteries
radial artery –> deep palmar arch
ulnar artery –> superficial palmar arch
popeye deformity
. If you tare the tendon of the long head of the biceps, this part of the muscle will curl up into a ball and it’s going to look like this. Tearing the tendon leads to Popeye’s deformity which needs to be surgically repaired.
flexor reticulum
- From scaphoid to pisiform and from trapezium to hamulus, these are two areas you have on either end the flexor retinaculum attaching on
- This is going to be one of the boundaries of the carpal tunnel:
- Floor of tunnel = carpal bones
Roof of tunnel = ligament that goes between the hamulus and pisiform and the trapezium and scaphoid
klumpke’s paralysis
lower plexus, C8-T1
ulnar nerve - “claw hand”
the arm that’s being pulled away from the trunk. If the arm of a baby presents first you are not to yank on that arm! Here again is our chap falling out of a tree but this time he grabs onto a branch so the weight of his body is pulling down while his arm is pulling upwards. This can damage these nerves. Primarily the most important nerve that will get affected is the ulnar nerve and it results in a deformity called claw hand which you’ll see when we study the hand.
superficial vs deep flexors in the fingers
deep flexors - into distal phalenges
superficial flexors - into middle phalanges
- The flexor digitorum profundus tendons end on the middle digit. These muscle sheaths engulf and encase the tendons of the flexor digitorum profundus muscles. So you have superficialis tendon wrapping around profundus tendon, and the profundus tendon goes all the way to the distal most phalanx.
- Functionally, this means that the superficialis tendons only flex the PROXIMAL interphalangeal joints (1)
- The profundus tendons can flex the DISTAL-most interphalangeal joints (2)
what is the funny bone?
ulnar nerve enters the flexor compartment of forearm by winding around medial epicondyle of humerus
superficial, easily injured
nerve branches of the lateral cord
lateral pectoral nerve - both pecs
musculocuaneous nerve - all muscles in anterior compartment (flexor) and skin
lateral head of the median nerve - combines with medial head and runs all the way to fingers
glenoid cavity of scapula
shallow concavity
humerus head is only partly in contact with it
“like a tee on a colfpall
for a lot of rotation
superficial palmar arch
main contribution from ulnar artery (u) and help from radial
lumbricals
- The lubricals are the worm-shaped muscles that originate off the long tendons and insert on the thumb side of the 4 fingers on the dorsal side.
- They cross the metacarpal-phalangial joint, where the metacarpal meets the first phalanx. Because they cross it, they can flex this joint.
- But because their tendon inserts on the dorsal side of the finger (they insert on the sheath that runs the whole surface), they are gonna extend the fingers.
- Lumbricals make your hand L-shaped.
scapular anastomoses
imp for gradual blockages
. Two vessels that are important in this scapular anastomoses. One we have not mentioned yet is the transverse cervical artery. The other one is superscapular artery. They are indirect branchings from subclavian. And they’re going to go down here towards the scapula. Lower down there is that circumflex scapular artery that I said comes from the front and goes into the triangular space. It’s going to anastomose with these two and that’s one channel by which blood can get to the more distal parts of the arm if there’s the blockage here. That only works if the blockage occurs slowly. If you have a vessel that’s getting narrower and narrower over time, or a clot that is growing slowly over time. If you have a sudden blockage there’s not enough time for these channels to open up and to have the blood flow sort of backwards to get to where it’s going.
what does the radial nerve do in the arm?
What does the radial nerve do in the arm? Triceps, sensory innervation below the sergeant’s patch area in the arm, sensory innervation all the way down the dorsal side of the forearm, and the dorsal side of the lateral part of the hand
cubital tunnel sydrome
ulnar nerve
- The ulnar nerve starts as the continuation of the medial cord.
- It is low down in the brachial plexus, C8-T1
- It comes down through the arm, does not do anything in the arm.
- Comes down around the medial epicondyle of the elbow through a little tunnel and held there by ligaments. It is called the cubital tunnel. (don’t nee to know the names of the ligaments!).
- When you bump your elbow, your little finger and part of your ring finger will tingle in addition to it hurting.
- Cubital tunnel syndrome
•Most common syndrome in the upper limb after carpal tunnel.
•You can get it by overflexing and supinating. People might sleep like this and wake up in the morning and have problems with the little finger and ring finger. The nerve gets stretches while sleeping. This will resolve.
shoulder vs hip socket
- Hip:
- Acetabulum provides greater contact to the femur making it more difficult to dislocated
Humerus, however, is held primarily by muscles and ligaments
Acromion, coracoid, and clavicle protect joint from above – thus it dislocates downward.
Arm more mobility since bones are loosely held together.
annular ligament
- So, we talked about the radial notch, where the radius fits in.
- There is also an annular ligament that goes around the radial notch
- Annular means “ring” à so it looks like a ring that goes around the radial head
what does subclavian artery become
axillary artry –> brachial artery
3 arterial anastamoses in the upper arm
- radial recurrent artery - connects deep artery of arm to radial artery
- middle collateral artery - connects deep artery of arm to common interoseus artery (via recurrent interosseus artery)
- superior and inferior collateral arteries - connect brachial artery to the ulnar artery (via posterior and anterior ulnar recurrent arteries respectively)
muscles of posterior compartment of the arm
triceps - 3 heads, extend arm when joint is flexed
anconeus - assist triceps
what sensory does the ulnar do on the hand
The palmar surface and the dorsal surface of the other half of the ring finger and the little finger all the way down to the base of the hand (the blue area) is innervated by the ulnar nerve.
intertendinous connections of fingers
why you can’t just bend one finger - strength
function of supraspinatous muscle
The first 15 degrees of abduction of the arm (deltoid is the rest)
*clinical corelation: if a pt has needs initial assistance with abducting their arm, but the rest of the movement is performed easily, there may be an issue with the supraspinatus muscle or supraspinatus nerve
what divisons of trunks form medial cord of branchial plexus?
anterior lower
bursa
Large joints and small joints have bursa, which is a small fluid filled sac with synovial fluid (sticky and reduces friction). Bursa increases Synovial fluid production when the bursa is irritated (repetitive motion) leading to bursitis
Bursas reduce friction for 2 structures (i.e. deltoid and humerus; 2 different bones)
Examples of bursitis:
- tennis elbow
- housemaid knees (named after maids that cleaned floors)
lumbricals muscles
- You have finger extensors in the dorsal part of the forearm, but you also have lumbricals that latch onto the posterior aspect and the dorsal side of the middle phalanx.
- These lumbrical muscles have their origins on the flexor tendons themselves and wrap around.
what innervates brachioradialis?
radial nerve
what does the clavicle articulate with?
- Clavicle articulates with sternum on medial end and the acromion, laterally
- Clavicle is most frequently broken bone in body (typically by falling on an outstretched arm)
- when clavicle is fractured, there are neck muscles attached to the medial side that hold it up
- muscles attached to lateral side, pull it down (looks like the shoulder is sagging)
palmar interossei
PAD - 3 muscles
ulnar nerve
function of coracobrachialis
flexes the shoulder joint not just the elbow
what spinal level does dorsal scapular nerve come from?
C5
skier’s thumb
Skier’s thumb
- Fall day while skiing and the ski pole puts pressure on the ulnar collateral ligament between the metacarpal and the first phalanges. It is very painful.
- Also called game keeper’s thumb because people who shoot small animals and birds get this while breaking necks.
- Has to be fixed surgically
carpal bones
Remember we had the distal ulna and radius. From there, we have 8 carpal bones:
- Scaphoid
- Lunate
- Triquetrum
- Pisiform
- Trapezium: under the thumb
- Trapezoid
- Capitate
- Hamate
interosseous membrane
located between radius and ulna
- This is what you call a syndesmosis
- (From wiki: A syndesmosis is a slightly movable articulation where the contiguous bony surfaces are united by an interosseous ligament)
- This is a joint that is bounded by a similar membrane.
- “Desmo” in Greek is a term for membrane
- “Syndesmosis” = 2 bones that share a membrane that join them
innervation of the forearm
- There’s a trend. When in doubt, if you forget what nerve innervates something in the flexor forearm, the chances are that it’s the median nerve or a branch of it.
- The only 2 exceptions are: the medial side of the flexor digitorum profundus and the flexor carpi ulnaris.
- An additional exception: the brachioradialis is innervated by the radial nerve.
how is the brachial plexus divided?
The brachial plexus is divided into roots, trunks, divisions, cords, and nerves. Remember red trucks drive cats nuts. The roots are going to combine to form trunks. The trunks are going to split up to form divisions. The divisions are going to recombine to form nerves.
common flexor tendon
forearm flexors - insert on humero-ulnar side
pronator teres
flexor carbi radialis
palmaris longus
flexor carpu ulnaris
flexor digitorum superficialis
nerve and blood supply of teres minor
- supplied by the axillary nerve and posterior circumflex humeral artery.
- Both originate anteriorly and wrap around posteriorly as shown above.
- also supply the deltoid
venous drainage of the arm
The cephalic vein you remember from last year. The basilica vein is also superficial like the cephalic and runs on the medial side. The cephalic is more lateral. Both of these veins begin all the way down in the hand and run all the way up. The cephalic vein will empty into the axillary vein. The basilica vein will join a deeper vein the brachial vein. And they will together empty into the axillary vein. The axillary becomes the subclavian vein as it approaches the heart. Here’s the vein that I was talking about that lies right on the biceps aponeurosis. It connects the basilica and cephalic veins right in front of the elbow and its called the median cubital vein. Cubital refers to the elbow.
what is the most commonly broken carpal bone?
scaphoid
- It happens when you fall down and break your fall with your hand, which is typical.
- Remember that the ulna has a very strong attachment or association with the humerus. The olecranon process bends into the olecranon fossa of the humerus.
- The radius, however, doesn’t really articulate with the humerus; it articulates with the ulna. When you pronate and supinate, the radius swivels around.
- So when you fall on your elbow, you tend to break the ulna rather than the radius.
- When you fall down on your wrist, the ulna has some distance between it and the carpal bones, while the radius is right against the scaphoid, which is up against trapezium and the thumb. When you fall down on your hand, you often break the scaphoid bone.
•What’s tricky about the scaphoid bone is the fact that it has some interesting blood supply.
•It gets its blood supply from the radial artery. A branch of the radial artery supplies blood to the scaphoid bone, but it is going to supply blood to the distal part of it. It doesn’t enter the proximal part and let it flow through the thumb; it enters distally.
•If you break the middle of the scaphoid bone, which is where it usually breaks, you isolate the part of the bone from the part that gets the blood supply. That’s how you get the aseptic necrosis. It makes a difficult reunion.
•Scaphoid fractures often don’t heal well.
interosseous muscles
You also have interosseous muscles that are in between the metacarpals
help extending fingers
wrist drop
Wrist drop
- If the patient can not extend their wrist, what nerve is that? Radial nerve (in charge of extension)
- What is the sensory innervation that you would test for radial nerve problems? Dorsal side of the middle finger, index finger, and thumb. NOT the nail beds. The nail beds get their innervation from the front.
palmaris longus muscle
•
- *The two biggest tendons are the tendon of flexor carpi radialis and the tendon of palmaris longus
- Note: Some people lack a palmaris longus muscle. But most people who lack it, only lack it on one side.
- There is a lot of variation within the same person on different sides. People are not always symmetric!
function of lattismus
- pulls body up toward arms in climbing (chinups)
- Adducts humerus (towards the body)
hypothenar muscles
opponenes digiti minimi
abductor digiti minimi
flexor digiti minimi
all supplied by ulnar nerve
OAF
superficial flexor muscles of the forearm
•all by median nerve EXCEPT flexor carpi ulnaris
Flexor muscles
- Pronator teres
- Flexor carpi radialis
- “Carpi” means wrist.
- It goes toward the thumb because the thumb is the radial side.
- Palmaris longus (if you have one)
- Goes into the palmar aponeurosis
- Flexor carpi ulnaris
- On the medial side
thenar eminience muscles
opponens pollicis
abdocutor pollicis previs
flexor pollicis previs
***all supplies by recurrent branch of median nerve
OAF
where does the axillary artery become the brachial artery>
right under the terres major
function of pec major
Pec major (left view)
- Attaches to clavicle, sternum, and arm
- medial rotator and ADductor
function of subclavious muscle
draws clavicle down and forward
IMPT: protects brachial plexus in clavicle fracture
Common extensor tendon
inserts on humero-radial side
extensor carpi radialis brevis
extensor digitorum
extensor digiti minimi
extensor carpi ulnaris
SLAP lesion
in adults, usually from pitching
laburm is torn from anterior to posterior
what nerves at risk for a humerus fracture near surgical neck
axillary nerve
if the humerus is fractured, what part is it usually?
Surgical neck (important): usually if you have a broken arm or shoulder, this is usually fractured
what innervates flexor carpi ulnaris?
ulnar nerv
common interosseus artery
branch of the ulnar artery
splits into anterior and posterior interosseus - blood to deep muscles
what muscles are used for lateral rotation of the arm
Infraspinatus, Teres minor, and Supraspinatus all attach to the greater tubercle
neurovascular bundle to the triceps
radial nerve
deep brachial artery
pectoral girdle
- pectoral girdle are bones (3) that attach the upper extremity to the trunk
- clavicle
- scapula
- humerus
three parts of axillary artery
continuation of subclavian
What divides it into three parts is the pectoralis minor muscle that lies right here. Pectoralis minor covers part 2. proximal to it is the first part. Distal to it is the third part. The axillary artery. And again below the teres major it changes its name again to brachial artery
coronoid fossa
- Coronoid fossa: depression
- As you flex and extend your forearm, the ulna is rotating on the trochlea and into the coronoid fossa
olecranon fossa
•Olecranon Fosa: From the posterior view, there’s an even deeper Fossa for where the olecranon fits in when your arm is extended
labrum
ridge of cartilage to make socket for humerus a little deeper
neurapraxia
putting weight on crutches in the axilla causes temporary numbness/paralysis
brachial artery and median nerve run under this aponeurosis.
what sensory does the radial nerve innervate on the hand
•The rest of the dorsum of the hand (the red area) is innervated by the superficial branch of the radial nerve.
what divisons of trunks form posterior cord of branchial plexus?
posterior upper
posterior middle
posterior lower
extensors of the thumb?
abductor pollicis longus
extensor pollicis brevis
extensor pollicis longus
gap = anatomical snuff ox with deep branch of radial neve!!
function of biceps
to supponate
. So the biceps, the most important function is as a supinator. It also flexes the elbow but mostly supinates. One thing I’d like you to focus on that the biceps ends as a little bump on a tendon called the radial tuberosity. But it also spreads out as this broad kind of aponeurosis. The biceps aponeurosis is important because a major vessel and nerve run underneath it. That’s the brachian artery and median nerve. They are protected by this biceps aponeurosis and we’ll see later why that’s important. What are they protected from?
intermediate layer of the forearm
flexor muscle - Composed of 1 muscle called the flexor digitorum superficialis, with many tendons
- Function: These are the superficial flexors of your digits. They help flex the digits.
- Note how the tendons go on into the carpal tunnel
- The muscle groups are also directly innervated by the median nerve
- Median nerve is always on the medial side of the biceps brachialis
- Median nerve comes down and gives off a branch that becomes the anterior interosseous nerve
- So, you will have a superficial branch of the median nerve (anterior interosseous nerve), and a deep branch that continues on as the median nerve with cutaneous branches to innervate other muscles
- Median nerve handles the anterior side of the forearm
radial nerve
splits into superficial and deep branches
deep - goes into supinator muscle
superfical - goes to snuff box
extensors of the fingers?
extensor digitorim
extensor digiti mini (pinky only)
superficial layer of forearm
flexor muscles
•Superficial layer is composed of muscles that will FLEX the wrist
These include: all others medial nerve
brachioradialis (radial nerve) - crosses comp
flexor carpi radialis,
flexor carpi ulnaris (ulnar nerve),
palmaris longus
pronator teres (does not flex - pronates)
- Note: Carpus means “wrist” in Greek
- The one muscle in the superficial compartment that does NOT flex the wrist is the pronator teres
- Pronator teres does NOT flex wrist, it pronates the forearm
Note: all these muscles have no influence on the fingers and they are all innervated directly by the median nerve
function of deltoid
- Abducts the arm, but cannot initiate abduction, which is performed by the supraspinatus.
- keeps humerus in place.
anatomical snuff box
lies between tendons of:
extensor policis longus (medially)
extensor plicis brevis + abductor policis longus (laterally)
floor: scapphoid and trapezium bones
contains: radial artery (can feel pulse)
superficial radial nerve over surface
suprascapular bundle
Suprascapular bundle supplies both supraspinatous and infraspinatous and travel through an opening under the spine of scapula has no name
suprascapular artery - off thyrocervical trunk
suprascapular nerve
what spinal levels for upper trunk of brachial plexus?
C5, C6
A patient is asked to make a fist. The right hand works but the left hand can’t make fist. Which nerve is that? Median nerve. The ring finger and the small finger still works. The median finger does the FDP and FDS on the index and middle fingers.
•This is also known as the pope’s benediction sign. This gets confused with the claw (not hyperextended).
sargent’s patch
for axillary nerve test (touch to see if sensory is working)
also place for injections
Axillary Nerve is endangered by fractures through the surgical neck of humerus – can test integrity of nerve by touching sergeant’s patch region (cutaneous supply by axillary nerve; injection site )
what is the “funny bone” sensation from/
- Groove for ulnar nerve:
- Ulnar nerve is a branch from the axilla that runs all the way down to your fingers, and causes the “funny bone” sensation when hit
what are the rotator cuff muscles
insert on joint capsule, also keep humerus next to glenoid
“SITS”
If you injure one of them you SITS out of the game… Supra is most commonly torn.
Blend w/ shoulder joint capsule to strengthen it. This cuff holds the humerus in place
supraspinatus
infraspinatous
terres minor
subscapularis
(other muscles rotate the arm but do not insert on should joint capsule)
how do you localize the problem to the carpal tunnel?
can look for a sensation to the palmar surface in area supplied by the palmar branchof the median nerve (branches from the median nerve before the tunnel)
- If there is no sensation here then you know that there was something wrong with the median nerve BEFORE it entered the carpal tunnel.
- What is another test to do to test the median nerve further up? Ask them to flex their wrist. If the median nerve isn’t working, the wrist will deviate towards the ulnar side. If it deviates to the radial side then you know that the median nerve is working and the ulnar nerve isn’t.
dorsal interossei
DAB - abduct
4 muscles
ulnar nerve
what spinal levels form lower trunk of brachial plexus?
C8, T1
biceps aponeurosis
the biceps ends as a little bump on a tendon called the radial tuberosity. But it also spreads out as this broad kind of aponeurosis. The biceps aponeurosis is important because a major vessel and nerve run underneath it. That’s the brachian artery and median nerve
a tear in which ligament gives you a separated shoulder?
coracoclavicular ligament
weight of arm pulls down and anteriorly
•important, because if you tear the coracoclavicular ligament, the coricoid process will be pulled down, and you’ll have a separated shoulder and the arm hangs down (might heal by itself)
Ligaments help hold bones near each other
Often named by the bones they connect
Rupture of coracoclavicular ligament is a separated shoulder – arm weight pulls scapula down, looks like bump on shoulder.
relationship of axillary artery to the cords of the brachial plexus
Ok. Why are they called lateral cord and medial cord and posterior cord? They are named in accordance with their relationship to the axillary artery. The lateral cord is lateral to the axillary artery. The medial cord is medial to it. The posterior code is not visible in this picture because it’s behind the artery.
allen test
to assess competency of ulnar artery to provide sufficient blood to hand of the radial artery is compromised after an arterial blood gas sampling/other procedure
carpal tunnel contents
9 tnedons and one nerve
flexor digitorum superficialis - 2, 3, 4, 5
flexor digitorum profundus tendons - 4
flexor pillicis longus tendon
mediam merve
roof = flexor retinaculum
anterior interosseous syndrome
- The patient (on the right side) can’t make the OKAY sign. What is not working? Flexor digitorum profundus innervated by the anterior interosseus nerve. They can’t bend tip down.
- Why can’t they bend the thumb down to meet it? Flexor pollicis longus is out. Also by anterior interosseus nerve.
- What is the third muscle innervated by the anterior interosseus nerve? Pronator quadratus.
function of trapezius
Functions: attaches pect girdle to trunk. Raise/lower/retract/tilts (tilts when arm is raised) scapula, tilt glenoid (to allow for full range of motion and prevent the humerus from crashing into bones lying superiorly
brachialis function
most powerful flexor of the elbow
function of pectoralis minor
draws scapula forward and down, as in forward reachng
deep branch of the radial nerve
dives into the supinator muscle
when emerges - called posterior interosseous nerve (deep branch of radial nerve) - So, just another view of how the posterior interosseous nerve – that is, the deep branch of the radial nerve – comes around and supplies innervation to all of these different muscles in the extensor compartment. By the way, the cutaneous portion supplies a lot of sensory innervation to posterior parts of hand, to forearm, and to arm.
what sensory does the median nerve innervate on the hand?
- The palmar surface, the nail bed, and the first phalanx of the thumb, the index finger, the middle finger, and half of the ring finger (the yellow area) is all innervated by the median nerve.
- The yellow area outside of the dotted line is innervated by the regular median nerve.
- The dotted area is innervated by the palmar branch that leaves before the median nerve enters the carpal tunnel.
deep compartment of the forearm
Deep compartment
- Most muscles are innervated by the anterior interosseous nerve (with some exceptions)
- The flexor pollicis longus, lateral flexor digitorum profundus, pronator quadratus are innervated by the anterior interosseous nerve
- Exceptions:
- Medial side of flexor digitorum profundus is innervated by ulnar nerve
- Note: profundus means “deep” in Latin
winged scapula
loss of serratus! because of a nerve (nerve to serratus anterior/long thoracic nerve)
keeps scapula in place against rips
extensor compartment of forearm
all innervated by radial nerve!!
extensors of wrist, fingers, movers of the thumb
what passes through the quadrangular space?
axillary nerve
posterior circumflex humoral artery
how do you extend fingers?
lumbricalis
dorsal and palmar interossei
what muscles are used for medial rotation of the arm
Teres major
Latissimus (a little)
erb’s palsy
upper plexus injury (esp C5-6)
That happens when the head is forcibly separated from the shoulder. And it results in an upper plexus injury. How can this happen? In a breach delivery if the head is coming out first, the obstetrician is yanking on the head while the shoulder is still stuck inside, this could cause damage to C5 and C6 the upper parts of the plexus. Also if you fall out of a tree or off of your motorcycle, your shoulder and head are going to be pulled in different directions. You’ll lose control of the shoulder muscles. You’ll lose flexion of the elbow, supination and even further down extensors of the hand. This results in something that looks like this. It’s called a waiter’s tip deformity. Your hand doesn’t move and the fingers are like that.
transverse scapular ligament
U shape cut out is suprascaular notch. Both sides of the notch are connected by the transverse scapular ligament
Suprascapular Nerve goes under the ligament and Suprascapular Artery goes over the ligament
*important in surgeries
what nerves at risk for a mid humeral fracture
radial nerve
nerve branches of the posterior cord
axillary - shoulder, deltoid, teres minor
radial nerve (biggest) - on posterior surface of the limb all the way down to hand
upper subscapular - subscapularis
thoracodorsal - latissmus
lower subscapular - subscapularis, teres major
deep flexor muscles of the forearm
- If you get rid of superficialis and look at the deepest part of the flexor forearm, you find flexor pollicis longus, which is the long flexor of the thumb, and flexor digitorum profundus, which has tendons flat as shown on the right image. Underneath, you have pronator quadratus.
- All of these muscles are also innervated by a branch of the median nerve—the anterior interosseus nerve—except for the 2 medial tendons of the flexor digitorum profundus, which are innervated by the ulnar nerve.
what does the anterior interosseus nerve supply?
flexor policis longus
pronator quadratus
lateral half of flexor digitorum
deep compartment
