Lecture 13 - Musculoskeletal 2 Flashcards
what is the most superficial muscle on the posterior surface of the pectoral girdle?
the trapezius
the trapezius has a very extensive ________
origin.
- it comes from superiorly and inferiorly in relation to its insertion
what does the trapezius origin pass through?
comes from the back of the skull, runs down BEHIND the cervical processes (along the ligamentum nuchae ligament), then at C7 it pick up the spinous processes and continues along the ligamentum nuchae to the T12 level.
what is the insertion of the trapezius
clavicle, acromion and the spine of the scapula
the trapezius insertion is also known at the anatomical?
horseshoe
what is the primary movement of the entire trapezius?
retracts the scapula
what is the insertion of the superior trapezius only?
clavicle
what is the primary movement of the superior trapezius only?
elevation of the scapula
what is the origin of the superior trapezius only?
back of the skull and the cervical vertebrae
what is the origin of the mid trapezius only?
part of the cervical and top of the thoracic vertebrae
what is the insertion of the mid trapezius only?
acromion
what is the primary movement of the mid trapezius only?
retraction of the scapula
what is the origin of the inferior trapezius only?
the lower thoracic vertebrae
what is the insertion of the inferior trapezius only?
the spine of the scapula
what is the primary movement of the inferior trapezius only?
depression of the scapula
what happens when the superior and inferior trapezius only contract and why?
superior rotation of the scapula
due to the synovial joint at the acromioclavicular joint
what three muscles are deep to trapezius
- lavator scapulae
- rhomboid major
- rhomboid minor
what is the origin and insertion of the levator scapulae
- upper cervical vertebrae
-> superior angle of the scapula
what is the primary movement of the levator scapulae
elevates the scapula
2º movement= inferiorly rotates the scapula
what is the origin and insertion of the rhomboid major
origins: C7 -> T5
Minor insertion: medial border of the scapula where the spine ends
Major insertion: the rest of the medial border
which is more superior, rhomboid major or minor?
rhomboid minor
true or false, rhomboid minor is smaller in width but thicker than rhomboid major
true
what is the primary movement of rhomboid major and minor?
retraction of the scapula
what is the secondary movement of rhomboid major and minor
elevates the scapula and inferiorly rotates the scapula
rank the rhomboid muscles, trapezius and latissimus dorsi in order of superficial to deep
trapezius -> latissimus dorsi -> rhomboid
what is the origin and insertion of the latissimus dorsi?
origin goes from T7 all the way to the saccrum.
in part originates from the iliac crest of the hip
insertion is the floor of the intertubercular groove on the anterior humerus (twists under the armpit)
what is unique about the origins of the latissimus dorsi?
it is the only muscle that originates at the other limb on the same side
is the latissimus dorsi a part of the pectoral girdle and why?
no, because it does not directly involve movement of the clavicle or scapula.
which muscle did we study that has an aponeurosis
latissimus dorsi. its muscle belly only starts a third of the way up. the rest is a flat tendon called an aponeurosis
what are the primary movements of the latissimus dorsi?
adduction of the humerus, and internally rotates the humerus
what are the secondary movements of latissimus dorsi
lower fibres can depress scapula and other fibred can inferiorly rotate the scapula by pulling on the humerus
how does paralysis of the serratus anterior cause a winged scapula
The serratus anterior normally protracts the scapula and holds it tight against the ribcage.
Without this function, the scapula becomes unstable and “floats” away from the ribs.
which two set of muscles allow the medial border (conceptual joint) of the scapula to ‘lock’ against the chest wall?
the rhomboid muscles and the serratus anterior. they oppose each other an pull opposite ways on the medial border of the scapula
- stabilises the mobile base of the pectoral girdle
what is the most mobile joint of the body
shoulder joint
- this means its the least stable
what secondary movement does abduction of the shoulder joint do
superior rotation of the scapula
what is circumduction?
- flex and extend
- abduct and adduct
- internal and external rotation
what makes the shoulder joint triaxial?
can circumduct.
what is the glenoid fossa?
one of the articulating surfaces of the shoulder joint.
- on the scapula
- forms the lateral border of the scapula
what structure surrounds the glenoid fossa to increase the depth of the socket?
the glenoid labrum
- very small difference
what are the supraglenoid and infraglenoid tubercules?
attachment site of muscles located just above and below the glenoid fossa
supra: long head of biceps brachii
Infra: long head of the triceps brachii
what fraction of the head of the humerus is in contact with the glenoid fossa
only about one third
what is the anatomical neck?
the narrow part of the humerus right by the head
what is the clinical importance of the surgical neck
the common break point of the humerus
what connects to the greater and lesser tubercle of the humerus?
rotator cuff muscles
3 attach onto the greater, 1 onto the lesser
what is another name for the inter-tubercular groove?
Bicipital groove
what two articulating surfaces make up the shoulder joint?
the scapula’s glenoid fossa and the humerus head
why does the fibrous capsule of the shoulder joint attach further down the humerus than other joints?
so the fibrous layer doesn’t get in the way (fowl on the articular bone) during adduction of the humerus
what does the synovial membrane cover in the shoulder joint
lines the fibrous capsule and all other structures that aren’t articulating against cartilage or other bone.
- tendon of the long head of biceps brachii (intracapcular)
what makes the supraglenoid tubercle an intercapsular structure?
the fact that the tendon of the biceps brachii and therefore the supraglenoid tubercule is inside the articular capsule.
is the infraglenoid tubercle intracapsular or extracapsular?
extracapsular
why is the fibrous capsule of the shoulder joint under the arm loose, and what does this mean for the stability of the joint?
to allow a lot of abduction
- this means there is a loss of passive stabilisation, and must instead use active stabilisation of muscles to hold it in place
what is the purpose of the coracoacromial ligament?
to prevent superior dislocation of the glenohumeral (shoulder) joint
what is the coracoacromial arch and its function?
formed by the coracoid, the coracoacromial ligament and the acromion
- forms a roof over the shoulder so it can’t move superiorly and anteriorly or superiorly and posteriorly
what is the only extracapsular ligament of the shoulder we learnt about?
coracoacromial ligament
what are the three capsular ligaments of the shoulder we need to know and their attachments?
- coracohumeral (base of the coracoid -> greater tubercule)
- transverse humeral (spans the intertubercular groove)
- glenohumeral (glenoid labrum -> articular capsule of humerus)
what are the two functions of the coracohumeral ligament?
- strengthens the superior ‘roof’ of ligaments over the shoulder
- suspends the humerus from the scapula along with the coracoclavicular ligaments, as it tightens as the arm is brought down to anatomical position
what is the function of the glenohumeral ligaments?
supports the anterior and inferior aspect of the shoulder
what is the function of the transverse humeral ligament?
covers the tendon of the long head biceps that sits in the intratubercular groove
what are the two structures that hold the long head tendon in place?
pectoralis major and the transverse humeral ligament
what protects the transverse humeral ligament from rubbing on the long head of biceps brachii
Sacciform synovial membrane
- basically a bulging out of the synovial membrane
what are bursa?
a synovial fluid-filled sac that reduces friction between structures like tendons, muscles, ligaments, and bones.
what bursa protects the greater tubercule muscles from rubbing against the coracoacromial arch
- subacromial bursa
but is continuous with - subdeltoid bursa
what two muscles do the bursa of the shoulder protect from abrasion from the coracoacromial arch?
supraspinatus and the intraspinatus of the rotator cuff
what bursa protect the subscapularis muscle/tendon?
subscapular bursa
what are the four rotator cuff muscles?
supraspinatus
infraspinatus
subscapularis
teres minor
which direction do we most often get shoulder dislocation and why?
inferiorly, due to there not being any active stabilisation (e.g no muscles) at the inferior part of the shoulder joint
what is anterior dislocation of the shoulder?
after dislocaiton, the head of the humerus is pulled anteriorly by latissimus dorsi and mostly pectoralis major
what is the origin and insertion of the subscapularis
origin - subscapular fossa
insertion - lesser tubercle
what is the only rotator cuff muscle in the anterior view and what movement does it do
subscapularis
internal rotation of the humerus
what is the origin and insertion of supraspinatus, infraspinatus and teres minor?
supraspinous fossa -> superior facet of the greater tubercle
infraspinous fossa -> middle facet of the greater tubercle
lateral border of the scapula -> inferior facet of the greater tubercle
what is the primary movement of the teres minor and the infraspinatus?
external rotation of the humerus
which rotator cuff muscle doesn’t rotate
the supraspinatus, which assists in arm abduction
what is the common insertion and the names of the majority of the rotator cuff muscles?
the greater tubercule
- Teres minor
- supraspinatus
- infraspinatus
