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