Sievert: Shoulder, Pectoral Region, Axilla, Arm Flashcards
It is important to consider if a muscle is attaching close to or far away from a joint. If the muscle attaches close to a joint, will it provide speed or power? If a muscle attaches further from the joint, will it provide speed or power?
speed; power
It is important to understand how a muscle attaches relative to its axis of (blank)
rotation
The shoulder girdle, including the arm and the scapula, has only one bony attachment. What is it?
sternoclavicular joint
Why is it important for the inferior angle of the scapula to move laterally?
for full abduction of the arm
What is different between the superior surface and the inferior surface of the clavicle?
superior surface is smooth, while the inferior surface is rough for attachment of ligaments
This is the first bone to ossify and the last long bone to fuse
clavicle
Most long bones undergo endochondral ossification, in which they begin with a cartilage model before laying down bone. How is the clavicle an exception?
The clavicle undergoes membranous ossification
At what two joints does the clavicle articulate?
At the acromioclavicular joint
and the sternoclavicular joint
On what axis does the scapula protract and retract (move anteriorly and posteriorly)?
vertical axis
As you protract the clavicle, the scapula can undergo about (blank) degrees of gliding movement as the scapula glides along the posterior chest wall.
15 degrees
The position of the scapula on the chest wall requires some mobility at the (blank) joint
acromioclavicular joint
What is the main stabilization of the scapula?
acromioclavicular joint
When there is a blow to the clavicle, where does it usually occur?
usually fractures just proximal to the coracoclavicular ligaments - near the middle and lateral third of the clavicle
What is a ligament that goes between the coricoid process (bony protrusion of the scapula anteriorly) and the acromion?
coracoacromial ligament
This ligament forms a roof for the glenohumeral joint, and helps rest the head of the humerus when weight is borne on an extended arm
coracoacromial ligament
Can the AC joint separate without tearing the coracoacromial ligament?
Yes, a shoulder separation is when some laxity is created in the AC joint. Does not have to be a complete tear.
What is more serious? Separation of AC joint or shoulder dislocation?
Shoulder dislocation, because the head of the humerus is forced out of the glenoid fossa
When you dislocate a shoulder, in what direction does it generally occur?
inferiorly and anteriorly
When would a shoulder dislocation most likely occur?
When you are abducted, because the head of the humerus is rotated outward and is making little contact with the glenoid fossa. Very little of the articular joint is intact, so the join will be relatively unstable.
T/F: There is a lot of blood flow and innervation that pass through the area where a shoulder dislocation occurs, and these vessels can be damaged or compressed.
True
The sternoclavicular joint is a typical synovial joint with two exceptions. What is its disc made of?
has an articular disc with two synovial cavities; made of fibrocartilage
In general, the upper extremities are designed for (blank), while the lower extremities are designed for (blank)
speed; power
What two bones make up the shoulder girdle? Where do the two bones articulate
scapula; clavicle; at the acromion
When does the clavicle ossify? When does it fuse?
week 5-6; fuses at 25 years
Where is the only bony attachment of the upper limb to the axial skeleton?
at the sternum
Two important ligaments of the shoulder
coracoclavicular ligament
coracoacromial ligament
Shoulder separation occurs at the (blank) joint, while shoulder dislocation occurs at the (blank) joint.
AC joint; glenohumeral joint
On what axis does the sternoclavicular joint protract and retract? Elevate and depress? Rotate medially and laterally?
vertical; AP; oblique
Movement of the inferior angle of the scapula medially or laterally
medial/lateral rotation
What portion of the abduction of the shoulder takes place at the glenohumeral joint? What portion takes place at the sternoclavicular joint? What is this combination of movements called?
120 degrees; 60 degrees; scapulohumeral rhythm
During abduction of the arm, you can only get 120 degrees of rotation at the glenohumeral joint. What is this assisted by? The last 60 degrees comes from lateral rotation at the sternoclavicular joint.
the deltoid
Can the arm fully abduct when the palms are facing medially?
No - arm must be laterally rotated to get full abduction
This muscle has an origin up the spinous processes of the vertebral column to the superior nuchal line of the head.
trapezius
There are three different parts of the trapezius. Upper, middle, and lower. On the vertical axis, what do each of these muscles cause? On the oblique axis, what do each of these muscles cause? On the AP axis, what do superior fibers do? What do inferior fibers do? Alas, what innervates the trapezius?
vertical axis: retraction
oblique axis: lateral rotation
AP axis: superior elevates, inferior depresses; innervation by CN XI
What nerve supplies motor function to the trapezius? What nerve segments supply proprioceptive innervation to the trapezius?
spinal accessory nerve (XI); cervical segments C3 and C4
This is a superficial (extrinsic) back muscle whose primary action is at the glenohumeral joint
latissimus dorsi
If you stabilize the glenohumeral joint, the latissimus dorsi will assist in retracting and depressing the shoulder girdle at the (blank) joint
sternoclavicular joint
The latissimus dorsi performs what actions? What’s its nerve supply? Where does it attach after leaving the thoracolumbar fascia?
adduction on AP axis
extendor of arm on transverse axis
medial rotator on the vertical axis;
nerve supply from thoracodorsal nerve (middle subscapular); attaches to the humerus
What do the rhomboids minor and major do? What’s their nerve supply?
retract the scapula
medially rotate scapula
elevate;
dorsal scapular nerve
What does the levator scapulae do? What’s its nerve supply?
elevates and medially rotates the scapula (pulls toward the midline); dorsal scapular nerve
Two other muscles that have an action at the SC joint
pec minor
serratus anterior
What’s the action of the pec minor on the coricoid process? What innervates the pec minor?
depressed
protracts
medially rotates;
medial pectoral nerve
Innervation to serratus anterior? What is unique about this?
Has a prominent nerve supply on its superficial surface – long thoracic nerve. Most muscles have their nerve supply on the deep side, but this nerve is on the superficial side. Can lead to nerve damage, which results in winging**
What is the main action of the serratus anterior?
Attaches to medial border but hugs the chest wall the whole way. Its major action is to hold the scapula tight against the body wall. If you push against something, it keeps the scapula from popping out.
Three actions of serratus:
AP axis
vertical axis
oblique
depression on AP axis
protraction on vertical axis
lateral rotation on oblique axis
Arm movements occur at the glenohumeral joint. But if you fix this joint, arms still need (blank) to facilitate all range of motion. In other words, movements of the (blank) are transmitted to the humerus.
the scapula; the…scapula
At the glenohumeral joint, what occurs along the horizontal transverse axis? The horizontal AP axis? The vertical axis?
flexion/extension
abduction/adduction
rotation
The glenohumeral joint is inherently unstable, because it allows for a lot of motion. It has a glenoid fossa and the articular surface of the head of the humerus. How much of the articular surface is in contact with the glenoid fossa?
only about half!
This tendon blends with the capsule of the glenohumeral joint, and helps hold the head of the humerus tightly against the glenoid fossa.
supraspinotis
This muscle comes off of the acromion, and a bit from the scapula. It is a prominent shoulder muscle that is unique, because it can perform every movement in the shoulder. It has anterior, middle, and posterior fibers (like the trapezius)
deltoid muscle
What movements do rotator cuff muscles allow for?
internal/external rotation and abduction/adduction
What keeps the deltoid from rubbing against the head of the humerus?
subdeltoid bursa
When you abduct your arm as much as possible with your palms medially rotated, what comes in contact with the acromion to inhibit motion?
greater tubercle of the humerus
**the acromion can be shaved down inferiorly to allow for more room for movement to avoid impingement associated with the acromion
Two “bursa” that provide protection to the glenohumeral joint?
subdeltoid bursa
subacromial bursa
Pec major. What’s it do at the GH joint? What’s it innervated by?
It flexes, adducts the arm, and allows for medial rotation; medial and lateral pectoral nerve
Does the deltoid have an attachment to the axial skeleton? Sooo, does it have action at the S-C joint?
It does not, it comes entirely from the shoulder girdle; no, it does not
Innervation of the deltoid? Action?
axillary nerve;
EVERYTHING!!! flexion, extension, abduction, adduction, medial and lateral rotation – it is capable of all of this because it has anterior, middle, and posterior fibers
If a muscle will have action on the sternoclavicular joint, it must have an origin from the (blank)
axial skeleton
This muscle looks just like the latissimus dorsi in terms of insertion into the humerus. It arises from the axial skeleton.
teres major
What innervates the latissimus dorsi and teres major?
middle subscapular of thoracodorsal (latissimus) and lower subscapular (teres)
Actions of latissimus and teres major at the GH joint?
extension
adduction
medial rotation
The rotator cuff adds stability to the glenohumeral joint. The muscles blend with and strengthen the capsule superiorly, posteriorly, and anteriorly. What are the four muscles?!
SITS: supraspinatus, infraspinatus, teres minor, subscapularis
Which muscles of the rotator cuff attach to the greater tubercle of the humerus? Which attach to the lesser tubercle?
supraspinatus, infraspinatus, and teres minor attach to the greater tubercle; subscapularis attaches to the lesser tubercle
The rotator cuff muscles allow for internal and external rotation. Which of these does the supraspinatus do?
NEITHER – the supraspinatus goes right through the axis
Which rotator cuff muscle is the most powerful medial rotator? Which are involved in lateral rotation? Which is involved in abduction?
subscapularis; infraspinatus and teres minor; supraspinatus
What is the blood and nerve supply to the supraspinatus and infraspinatus?
suprascapular nerve and artery
What is the blood and nerve supply to the terres minor?
axillary nerve and post humeral circulflex artery
What is the blood and nerve supply to the subscapularis?
upper and lower subscapulars and circumflex scapular artery
What is unique about the suprascapular nerve? Does it apply to the corresponding artery?
The suprascapular nerve passes through the suprascapular notch, which is formed by the transverse scapular ligament. This nerve can be impinged in the notch (esp in weight lifters) and can cut off supply to supraspinatus and infraspinatus. The artery does not pass through the notch!!
Does the terres major pass anterior or posterior to the humerus?
anterior to the humerus
These two muscles form the axillary (quadrilateral) space, which is important because the axillary nerve and posterior circumflex pass through on their way to the deltoid and terres minor.
teres major and teres minor
What forms the suprascapular notch in which the suprascapular nerve passes through?
transverse scapular ligament
4 arteries that have collateral flow to the shoulder joint
dorsal scapular
suprascapular artery
posterior circumflex humeral
circumflex scapular from subscapular artery
The shoulder joint has very significant collateral flow. Can receive branches from these nerves, surprisingly!
anterior and posterior intercostals, as well as the internal thoracic artery, which can connect with the dorsal scapular artery
If there is a damage to zones supplied by the axillary artery, can you still get blood flow to the upper extremity?
Yes, almost all joints of extremities have collateral flow
What’s the difference between the anatomical neck and the surgical neck of the humerus? Where is the humerus more commonly fractured?
The surgical neck is below the greater and lesser tubercles, and is kind of along the shaft of the humerus, while the anatomical neck separates the head of the humerus from the two tubercles (it’s up higher). Fractures more typically occur at surgical neck!
What nerve and artery will damage to the surgical neck cause the most problems with?
A fracture in this area is most likely to cause damage to the axillary nerve and posterior circumflex humeral artery
Is the trochlea or capitulum for medial?
trochlea
What is the action along the AP axis of the glenohumeral joint? Vertical axis? Transverse axis
abduction/adduction; rotation; flex and extend
What is the axis at the humeroulnar joint, and what movements does this allow for?
transverse axis, allows for flexion and extension
What is the axis at the humeroradial joint, and what movements does this allow for?
transverse (flex and extend) vertical rotation (pronate and supinate)
The axillary artery provides blood to the upper extremity. At what point does the axillary artery begin? What was it before this point? Where does it end? What does it become?
Begins after crossing the first rib - was previously the subclavian artery. Ends at the lower border of the teres major - becomes the brachial artery.
The axillary artery splits into three segments by what muscle? How many branches does each segment have?
pec minor; first segment has one, second segment has two, third segment has three
Where does the supreme thoracic artery go? The thoracoacromial distributes to a lot of areas. Where does the lateral thoracic go?
superior thoracic goes to first two thoracic spaces
Thoracocromial: distributes to a lot of areas
Lateral thoracic: parallels long thoracic and goes to serattus anterior on anterior surface
This is another branch off of the axillary artery that gives of off the circumflex scapular artery and the thoracodorsal, which supplies the latissimus dorsi
subscapular artery
Two lower branches off the axillary artery. Which travels with the axillary nerve through the axillary space?
anterior and posterior humeral circumflex; posterior travels with the nerve through the quadrilateral space
What happens distal to the brachial artery if it is ligated? Will there still be flow?
brachial artery can be ligated distal to the profunda due to the anastomosis between numerous recurrents and collaterals at the elbow :)
One you get to the brachial artery and head down toward forearm, you reach elbow joint. A lot of this artery passes (blank) to the joint. So, during severe flexion, can cause restriction of flow, but there is collateral flow to circumvent reduction of flow.
anterior
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
Boundaries of the axilla: anterior posterior medially laterally
pec major anteriorly
latissimus dorsi posteriorly
serratus anterior medially
humerus laterally
What artery and nerve supply the latissimus dorsi?
thoracodorsal artery and nerve
What is contained within the axillary fossa?
axillary artery and vein - artery is surrounded by medial, lateral, and posterior cords
How many roots are there in the brachial plexus? List them. How many trunks are there? List them. How many divisions? List them. How many cords? List them? How many terminal branches? …list them.
5 roots: C5, C6, C7, C8, T1 3 trunks: superior, middle, inferior 3 divisions: 3 anterior and 3 posterior 3 cords: lateral, medial, posterior terminal branches: musculocutaneous, axillary, radial, median, ulnar
Which two cervical nerves make up the superior trunk of the brachial plexus?
C5 and C6
Which nerve makes up the middle trunk of the brachial plexus?
C7
Which nerves make up the inferior trunk of the brachial plexus?
C8 and T1
Each trunk of the brachial plexus then divides into anterior and posterior divisions. Where does each anterior division nerve go? Posterior divisions nerves?
anterior divisions nerves go to anterior compartment muscles, while posterior division nerves go to posterior compartment muscles
Where can branches arise from along the brachial plexus?
roots
trunks
cords
and terminal branches
Branches of the terminal branches of the brachial plexus go to compartments of the upper extremity. List these terminal branches
musculocutaneous axillary radial median ulnar
What is an acronym for remembering all about the brachial plexus?
Rod: Roots C5-T1 Tidwell: Trunks upper/middle/lower Drinks: divisions anterior/posterior Cold: cords lateral/medial/posterior Beer: branches (MARMU)
Which two nerve roots of brachial plexus generally facilitate the movement of shoulder joint (glenohumeral joint)?
C5 and C6
Which two nerve roots of brachial plexus allow for movement at the elbow?
C6 and C7
Which two nerve roots of the brachial plexus allow for movement at the wrist?
C7 and C8
Which two nerve roots of the brachial plexus allow for movement at the hand?
C8 and T1
Which branch of the brachial plexus supplies the anterior arm?
musculocutaneous
Which branch of the brachial plexus supplies the shoulder in the posterior compartment? Which branch supplies the posterior arm and forearm?
axillary (deltoid and teres minor);
radial
Which branches off the brachial plexus arise from roots?
dorsal scapular
long thoracic
What branches off the brachial plexus arise from the cords?
lateral cord - lateral pec
posterior cord - upper, middle, and lower subscapulars
medial cord - m. pectoral, m. brachial, m. antebrachial cutaneous
What is the dermatome of the thumb?
C6 (6 shooter)
What is the dermatome of the little finger?
C8
There is a big difference between dermatomes and cutaneous nerves. What are dermatomes useful for?
dermatomes are useful for looking at damage to the spinal cord and nerve roots. If there is damage to a terminal branch of the brachial plexus, it may involve several dermatomes.
What happens to nerve roots when they enter the brachial plexus? Why is this important … what happens if you cut a single peripheral nerve?
Nerve roots can become mixed up into several peripheral nerves. If you cut a single peripheral nerve, it has multiple ventral root fibers in it, so it will cross dermatomes.
Basically, does peripheral nerve damage follow a dermatomal pattern?
NO
What separates the anterior from the posterior compartment of the arm?
intermuscular septum
What are the muscles of the anterior compartment of the arm?
biceps brachii
brachialis
(coracobrachialis?)
What are the components of the posterior compartment of the arm?
long head of triceps
lateral head
medial head
Which nerves pass through the arm on their way to the forearm? Which nerve travels with the deep brachial artery to supply all heads of the tricep?
ulnar and superior ulnar collateral nerve; radial nerve
Which head of the tricep is the one that crosses the shoulder joint?
long head
What is the only nerve of the anterior compartment of the arm? What does it supply?
musculocutaneous - supplies biceps brachii, brachialis, and coracobrachialis
Where is the major attachment of the biceps?
at the radial tuberosity (this plays a major role in supranation of the forearm)
This muscle parallels the short head of the bicep, but does not cross the elbow joint. Its main action is flexion, and it can also medially rotate.
coracobrachialis
Where do the two heads of the bicep attach to? Where does the brachialis attach to? What about the coracobrachialis?
Two heads of bicep down to radial tuberosity. Brachialis to the ulna. Coracobrachialus only to humerus.
What is the triceps muscle specialized for due to its attachment close to its axis of rotation?
speed
This nerve innervates muscles all the way down to the hand, so damage at the humerus (which it is susceptible to) can cause loss of sensation all the way to the hand.
radial nerve
If the axillary nerve is damaged in a fracture of the surgical neck of the humerus, will there be a complete loss of abduction and lateral rotation?
Not a complete loss, just weakened
What happens if you damage the musculocutaneous nerve?
almost no forearm flexion possible
weakened arm flexion
What happens if you damage the radial nerve?
no forearm extension
forearm may be slightly flexed
3 muscles that attach at the coracoid process of the scapula
pec minor
biceps brachii
coracobrachialis
