Extrinsic Back Muscles, Shoulder and Pectoral Regions, Brachial Plexus and Arm Flashcards
The force a muscle exerts at a joint axis depends on a number of factors such as ????
size and shape,
angle of pull relative to axis
insertion site
In general, the upper extremities are designed for (blank) and the lower extremities are designed for (blanK)
speed
power
All muscle help to stabilize the (blank) they cross
joint
What is the arm?
elbow to shoulder
What determines muscle function/
orientation of muscle fibers, how muscle is attached to a joint, and angle of pull elative to axis
Where does the clavicle articulate with the scapula?
acromian
Where does the scapula articulate with the humerus?
glenoid cavity/fossa
What 2 bones make up the shoulder girdle?
clavicle and scapula
Is the scapula fused to anything? Why is this important?
no it is held up by muscle
Because it allows for great range of motion
How can the inferior angle of the scapula move and why is this important?
it can move medially and laterally and this is important for full abduction
What does full abduction require of the scapula?
lateral rotation of the inferior angle and elevation of the glenoid fossa
What is the origin of the clavicle?
intramembranous ossification
What is the first long bone to ossify (week 5-6)? What is the last long bone to fuse (25 years)?
clavicle
clavicle
How can you tell the superior side from the inferior side of the clavicle?
the inferior side is rough for attachments of ligaments
superior side is smooth
Note the only bony attachment of the upper limb to the axial skeleton is the (blank).
sternum via the sternoclavicular joint)
When you push your scapula forward or backward (protraction and retraction) what joint allows you to move your scapula across the curves of your ribs?
AC joint
What two joints are necessary for protraction and retraction of your scapula?
AC and SC joints
Where is the coracoacromial ligament located and what is it useful for?
It is connected from one part (coracoid process) of the scapula to the other (acromion) .
To prevent humerus from pushing into the scapula (i.e forms the roof to the glenohumeral joint)
What is the glenohumeral joint?
The joint between the glenoid fossa of the scapula to the humerus
Where do you get the most common clavicular fractures?
Why?
you get them between the middle and lateral thirds
Because between the coracoclavicular ligaments and the coracoacromial ligaments is weak.
Should separation occurs at the (blank) joint whereas dislocation occurs at the (blank) joint.
AC
glenohumeral
In a fall capable of separating the AC joint a person will often fracture the (blank)
clavicle
How do you get a shoulder separation?
you snap your AC ligament (can also mess up your coracoclavicular ligaments too)
in what direction do shoulders most commonly dislocate and how do you do it?
inferiorly and anteriorly
via abduction cuz you have very little contact with articular processes
Which is more dangerous, a shoulder separation or a shoulder dislocation and why?
a should dislocation because you can impinge on nerves and blood vessels
What does the sternoclavicular ligament have?
it is an articular disc
How many synovial cavities are in the articular disc and why?
2 because it gives stability
The disc found in the S-C joint like most discs is made of (blank) .
fibrocartilage
what ligament connects the clavicle to the ribs?
costoclavicular ligament
With the sternoclavicular joint, what kind of axis do you have with the following movments: 1) protraction/retraction? 2) elevation/depression? 3) medial/lateral rotation?
vertical axis
AP axis
Oblique axis
If you are moving the inferior angle of the scapula medially or laterally, what axis will you be moving around?
the oblique axis
What would the levator scapula do on the AP axis?
move up and down
Why is lateral rotation important for normal limb movements?
Cuz you need the lateral rotation to reach 180 degrees of abduction (cuz the glenohumeral joint can only undergo 120 degrees of rotation)
Movement of the inferior angle in either a lateral or medial direction defines (blank and blank) rotation
lateral and medial
Only a portion (120 degreee) of the 180 degree of abduction at the should takes place at the (blank) . Therefore the extra 60 degrees comes from where?
glenohumeral joint
sternoclavicular joint
(blank) is the prime abductor
deltoid
What is scapulohumeral rhythm?
for every 2 degrees of motion in the glenohumeral joint you get 1 degree of motion in the sternoclavicular joint
What are the three parts that the trapezius can be divided into?
upper, middle, and lower
Do all the parts of the trapezius move the same way?
no, they each perform different movement
When the muscles of the trapezius rotate around the vertical axis, how do they move?
retract
When the muscles of the trapezius (superior) elevate and (inferior) depress, what axis is this around?
the AP axis
When the trapezius muscles laterally rotate, what axis do they go around?
the oblique axis
What is the innervation to the trapezius?
CN XI
If you tear the brachial plexus can you still move your trapezius?
yup cuz of CN XI
If you flip the trapezius up, what nerve will be exposed and be running down from under the neck?
spinal accessory nerve (XI) and the cervical nerves C3 and C4
What does spinal accessory nerve (XI) supply to the trapezius?
motor
What do the cervical segments C3 and C4 supply to the trapezius?
proprioceptive
Where is the primary action of the latissimus dorsi?
at the glenohumeral joint
If you stabilize the glenohumeral joint, what will the latissimus dorsi do?
it will assist in retracting and depressing the shoulder girdle at the S-C joint
What does the latissimis dorsi attach to at the humerus?
the intertubercular groove
What kind of movements is the lat dorsi responsible for?
powerful adductor of arm, extensor of arm, and medially rotates arm (climbing, swimming)
(it attaches to the front of the humerus)
What is the nerve supply to the latissimus dorsi?
thoracodorsal nerve (middle subscapular)
How does the Latissimus dorsi move on each of the following axes:
transverse?
verticle?
AP?
extend
medial rotator and extender
adductor
What are the three superficial back muscles that act on the scapula?
trapezius
levator scapulae
rhomboids
What do they rhomboids do and what innervates them?
retract scapula and medially rotates scapula
dorsal scapular nerve
What does the levator scapulae do?
elevates the scapula, medially rotates scapula, same side rotation of neck, and neck extension
What is the nerve supply to the levator scapulae?
dorsal scapular
Besides the extrinsic back muscles, what 2 other muscles have an action at the S-C joint?
the pectoralis minor and the serratus anterior
What is the innervation of the pectoralis minor?
medial pectoral nerve
What are the actions of the pectoralis minor on the girdle?
depresses
protracts
medially rotates
What is important in holding the medial border of the scapula tight against the ribs?
serratus anterior
What are the actions of the serratus anterior on the shoulder girdle at the S-C joint?
Depresses on AP axis
Protracts on vertical axis
Laterally rotates on oblique axis
What is the innervation to the serratus anterior?
the long thoracic
What happens if you damage the long thoracic?
you get scapular winging
When you have lateral rotation what axis are you rotating around?
oblique
What kind of rotation is it when you elbow someone in the face?
lateral rotation via serratus anterior on the oblique axis
What muscles of the SC-Joint undergo protraction?
serratus anterior
pectoralis minor
What muscles of the SC joint undergo retraction?
trapezius (middle)
rhomboid major and minor
What muscles of the SC joint undergo elevation?
trapezius (upper)
levator scapulae
rhomboid major and minor
What muscles of the SC joint undergo depression?
serratus anterior
pectoralis minor
trapezius (lower)
What muscles of the SC joint undergo medial rotation?
pectoralis minor
rhomboid major and minor
levator scapulae
What muscles of the SC joint undergo lateral rotation?
trapezius (all parts)
serratus anterior
Movements of scapula are transmitted to the (blank)
humerus
Arm movements occur at the (blank) joint and the (blank) to faciliatate all range of motion that we get
glenohumeral
scapular
If you got rid of all your muscles at the glenohumeral joint, could you still move your humerus?
yes because you can move your scapula :)
What are the movements allowed at the glenohumeral joint on each axis:
horizontal/transverse axis?
horizontal AP axis?
vertical axis?
flexion/extension
abduction/adduction
rotation
What would be a good extender at the glenohumeral joint?
the latissimus dorsi
What would be a good flexor at the glenohumeral joint?
the pectoralis major muscle
What joint is the one that we can dislocate and why?
the glenohumeral joint because the articular surface of the humerus isnt really intact with the glenoid fossa (to allow for a lot of motion)
How do we stabilize the glenohumeral shoulder joint?
with pieces of cartilage called the glenoid labrum and tendons of the rotator cuff
Whenever you sacrifice stability for motion, the joint becomes susceptible to (blank)
damage
What is a super stable joint?
the hip joint
How do all the tendons of the rotator cuff work?
they blend into the glenohumeral joint capsule to provide stability
What kind of movements do the rotator cuff muscles allow for?
external rotation (lateral), internal rotation (medial), abduction and adduction
What comes of the acrominan, the clavicle and the spine of the scapula?
the deltoid
The (blank)is a prominent muscle on the shoulder-> it can perform every movement in the shoulder, can undergo abduction and adduction cuz it has anterior, posterior and middle fibers (similar to traps).
Deltoid muscle
Why cant we abduct our humerus past 130 degrees w/out anterior lateral rotation?
because we would hit the greater tubercle of the humerus on the acromian.
Any joint that has movement available has what and what are they for?
a bursa
for protection of the muscle as it passes across bony structures
What does the subdeltoid bursa do?
protects the deltoid from the greater tubercle of the humerus
This holds a tendon of the long head of the bicep in place and when the tendon slides up and down, this protects it from damage by the ligamentou structure crossing it.
the bursa of the bicep tendon
What is the innervation to the pectoralis major?
the medial and lateral pectoral nerve
What joint does the pectoralis major act on?
the GH joint
What are the movements of the pectoralis major on the GH joint?
Flexion
adduction
medial rotation
What is the unique muscle that is capable of acting on the GH joint and eliciting every kind of motion?
the deltoid
What innervates the deltoid?
axillary nerve
Is the deltoid attached to the axial skeleton? So what does this mean?
no
It has no action at the SC joint
When we are talking about flexion of the arm, what way is the arm moving?
towards the face
What action do the anterior fibers of the deltoid elicit?
Posterior fibers?
middle fibers?
posterior and anterior?
flexion and medial rotation
extension and lateral rotation
abduction
adduction
what has the same type of insertion into the arm as the Latissimu dorsi?
the teres major
What is the nerve innervation to the latissimus dorsi?
the middle subscapular AKA thoracodorsal
What is the nerve innervation to the teres major?
the lower subscapular nerve
What are the latissimus dorsi and teres major?
extension
adduction
medial rotation
If a muscle is going to perform an action at the SC joint, it must have an origin where?
Do both the latissimus dorsi and teres major have an origin here?
axial skeleton
NO, only the Lats, meaning only the lats will elicit an action on the SC joint
Teres major comes from the scapula**
The glenohumeral joint is built for (blank)
mobility
The (blank) adds stability to the glenohumeral joint
rotator cuff
The (blank) functions of the muscles help with full range of the glenohumeral joint
rotatory
(blank) rotation of the humerus during flexion or abduction prevents the greater tubercle from hitting the acromion.
external rotation.
What makes up the rotator cuff muscle?
SITS
Supraspinous, infraspinous, teres minor, subscapularis
Where do the SITS muscles lay and what are they attached to.
on top of the greater tubercle and attached to the greater tubercle of the humerus (except for the subscapularis which hangs anterior to greater tubercle and attaches to the lesser tubercle)
What do the SITS muscles (besides the supraspinotous) do?
What does the supraspinotous do?
they assist in rotation and create stability
facilitate abduction
What movement does the subscapularis allow for?
medial rotation
What movement does the infraspinatus allow for?
lateral rotation
What movement does the teres minor allow for?
lateral rotation
What is the powerful medial rotator used in arm wrestling?
subscapularis
What happens with repetitive motion in an abducted position (i.e throwing a baseball)?
rotator cuff tear!
Which passes through passes through the suprascapular notch (hole made by the superior transverse scapular ligament), the suprascapular nerve or artery?
the nerve passes through the notch, while the artery passes over the superior transverse scapular ligament
What nerve and what artery innervates the supraspinatus, and infraspinatus muscles?
the suprascapular nerve and artery
What nerve and what artery innervates the teres minor?
axillary nerve and post humeral circumflex artery
Can you impinge the suprascapular nerve and how?
yes you can via weight lifting you can impinge it in the suprascuplar notch
What makes up the quadrangular space?
the teres minor and teres major
How can you tell you are looking at the teres major vs the teres minor?
the teres minor is going to the greater tubercle and the teres major is anterior to the humerus
What runs through the quadrangular space made by the teres major and minor?
the posterior humeral circumflex artery and the axillary nerve on their way to the deltoid and teres minor
What is the blood supply and nerve innervation to the subscapularis muscle?
upper and lower subscapular nerves
circumflex scapular artery
What are the four blood supplies to the shoulder that have extensive anastomoses with each other?
Besides these arteries, what other artery supplies the shoulder with collaterol flow,
dorsal scapular artery
suprascapular artery
posterior circumflex humeral artery
circumflex scapular from subscapular artery
The internal thoracic by means of the intercostal arteries
If you have damage to your axillary artery, are you dead?
no, you got collateral flow
In general, almost all the joints have extensive (blank)
collateral flow
At the glenohumeral joint, what axis will you be moving around if you are moving ab and add?
How about rotation?
How about flex and extend?
AP
vertical
transverse
At the humeroulnar joint, what axis will you be moving around if you flexing and extending?
tranverse
At the humeroradial joint, what axis will you be moving if you are flex and extending?
How about rotation (pronation and supination)?
transverse
vertical
What artery am I talking about;
begins after crossing first rib?
axillary artery
Where does the axillary artery end?
ends at lower border of teres major
How many segments does the axillary artery break into?
3 baby
How many branches are come off the first segment of the axillary artery?
second segment?
third segment?
1
2
3
What do we call the axillary artery after the teres major?
it is called the brachial artery
What are the branches of the axillary artery
Supreme thoracic
thoracocromial trunk
lateral thoracic
subscapular (circumflex scapular and thoracodorsal)
anterior humeral circumflex
posterior humeral circumflex
Mnemonic: Suzy Thompkins Loves Sex (C and T) Alcohol and Drugs
Which is larger, the anterior or posterior humeral circumflex?
posterior humeral circumflex (cuz remember your triceps are big)
Which is larger, the anterior or posterior humeral circumflex?
posterior humeral circumflex (cuz remember your triceps are big)
Why is it important that we have collateral flow the elbow?
cuz when we flex our biceps we cut off our blood flow from the brachial artery
Why is it important that we have collateral flow the elbow?
cuz when we flex our biceps we cut off our blood flow from the brachial artery
What is the space below the shoulder joint, bounded by the pectoralis major anteriorly, the latissimus dorsi posteriorly, the serratus anterior medially and the humerus laterally?
axilla
Why is the axilla important?
it contains the brachial plexus, the axillary artery and axillary vein
Why is the axilla important?
it contains the brachial plexus and the axillary artery
Explain the posterior wall of the axilla
Subscapularis, Quadrangular space (with axillary nerve and posterior circumflex artery) Lats, Thoracodorsal artery and nerve Teres major, Anterior circumflex
(Some, Quiet, Lovers, Think Terribly Atrocious (things))
Explain the posterior wall of the axilla
subscapularis, teres major, lats, thoracodorsal artery and nerve
quadrangular space with axillary nerve and posterior circumflex artery and anterior circumflex
Tell me about the medial wall of the axilla?
long thoracic and serratus anterior
What cervical nerve innervates the shoulder joint?
C5, C6 (myotomes)
What cervical nerve innervates the elbow?
C6, C7 (myotomes)
What cervical nerve innervates the wrist?
C7, C8 (myotomes)
What nerves innervate the hand?
C8 and T1 (myotomes)
What is the carpus?
What is the metacarpus?
What is the phalanges?
the wrist
the bones in your hand
your fingers in your bone
What is the orientation of the axillary artery, vein and brachial plexus in the axilla?
axillary artery breaks the brachial plexus into three parts with the medial cord anterior, the lateral cord laterally and the posterior cord posterior. With the axillary vein medial
The anterior compartment of your arm (like bicep area) is innervated by what?
musculocutaneous (motor)
The posterior compartment of your axillary/shoulder area (like deltoid and teres minor) is innervated by what?
axillary nerve
The posterior compartment of your arm and forearm is innervated by what nerve?
radial nerve
What branches come off the nerve roots of the brachial plexus?
dorsal scapular, long thoracic
What branch comes off the nerve trunks of the brachial plexus?
suprascapular
What branches come off the nerve cords of the brachial plexus?
lateral pectoral
upper, middle (thoracodorsal) and lower subscapular
M. pectoral, M. brachial cutaneous, M antebrachial cutaneous
What are the terminal branches of the brachial plexus?
musculocutaneous axillary radial median ulnar
What are myotomes?
they give motor innervation to a certain set of muscles in a particular pattern
What are dermatomes?
an area of skin that is mainly supplied by a single spinal nerve (relays sensation and pain)
What dermatome goes from your shoulder to your thumb?
C6
What dermatome goes from your back to your little finger?
C8
What dermatome is your chest area?
T1
What dermatome is from center of sternum, down middle of forearm to middle wrist?
c5
If your particular pattern of loss doesnt represent a dermatome what could be the issue?
an issue in the brachial plexus resulting in loss of cutaneous innervation to a particular part of the body
What nerve roots make up the axillary nerve?
C5/C6
What nerve roots make up the radial nerve?
C5,C6,C7,C8, T1 (all of them)
What nerve roots make up the ulnar nerve?
C8,T1
What nerve roots make up the median nerve?
C5,C6,C7,C8 (all the Cs) T1
What nerve roots make up the medial antebrachial cutaneous nerve?
C8,T1
What nerve root makes up the lateral antebrachial cutaneous?
C5,C6,C7
What is the lateral antebrachial cutaneous?
a branch off the musculocutaneous
What are the muscles in the anterior compartment of the arm?
biceps brachii (long and short head)
brachialis
coracobrachialis
What are the muscles in the posterior compartment of the arm?
triceps (long, medial, lateral heads)
What does the ulnar and superior ulnar collateral nerve do in the arm?
NOTHING SUCKA!
Where does the radial nerve and the profunda brachii artery run in the humerus?
in the spiral groove of the humerus
The (blnk) head is the only that crosses the shoulder joint of the tricep
long
the (blank and blank) head have action at the elbow only of the tricep
medial and lateral
The tendon of the bicep connects to the radius underneath a cT band called the (blank) which attaches to radial tuberosity
bicipital aponeurosis
What plays an important role in supination of the forearm in addition to its role in flexion?
bicep
What goes in through the capsule, up over the humerous and into the glenoid capsule.
The long head of the bicep
The long head attaches to the glenoid labrum, so if you have a fall on your bicep what can result?
glenoid labrum
If you do pulls up like me (palms out) what do you work out?
the brachialis
If you do pull ups palms in what do you work out?
the biceps
What attaches to the corocoid process parallel to the short head of the bicep and attaches to the humerus without crossing the elbow joint and works by flexing and acting as a medial rotator?
the coracobrachilais
What does the brachialis do?
flex (crosses the elbow joint)
Biceps attach to (blank)
Brachilis attaches to (blank)
coricobrachialis attaches to (blank)
radius
ulnar
humerus
THe posterior compartment muscles of the arm (triceps) attaches to the (blank).
olecranon process by the tricep tendon
There are three heads of the tricep, the lateral, medial and long head, which head crosses the shoulder joint? The (blank) head attaches to the glenoid fossa. The (blank) head is only seen when the lateral head is reflected.
long head
lateral head
medial head
The triceps are specialized in (blank) because they are shortish and have a very close attachment to the axis.
speed
Is it common to tear the radial nerve?
yes, cuz if you get a mid-humeral fracture you are screwed
What nerve, if damaged will result in severely weakened abduction, weakened lateral rotation?
axillary nerve
you have weakened abduction and lateral rotation cuz you lose the deltoid and teres minor
What nerve, if damaged will result in almost no forearm flexion, weakened arm flexion?
musculocutaneous nerve (take out coracobrachialis and short head of the bicep)
What nerve can be damaged in a surgical neck of the humerus fracture?
the axillary nerve
surgical neck fractures are more common the anatomical neck fracture*
What nerve can be damaged in a surgical neck of the humerus fracture?
the axillary nerve
surgical neck fractures are more common the anatomical neck fracture*
Why would you have a slightly flexed arm if you lost your radial nerve?
Cuz you wouldnt have any extensors to counteract the action of the flexors.
What are the two ligaments that make up the coracoclavicular joint?
the trapezoid (most lateral) and conoid ligaments
