Flashcards in pectoral girdle Deck (57)
what does the pectoral girdle include? what are its signature characteristics and the function of these? where does it get support and stabilization?
clavicle and scapula in an incomplete ring (open posteriorly) to allow mobility +independent motion
-support and stabilization by axio-appendicular muscles
what is the sternoclavicular joint?
single articulation between the pectoral girdle and the axial skeleton. (scapula has no articulation w/ axial- only attached via muscles)
what are the 3 chief characteristics of the clavicle? expand on each.
1.Elongated S shape
--Convex medially (curve protudes anteriorly)
2.Enlarged sternal (medial) end
--Articulates with manubrium
--Sternoclavicular joint (SC)
3.Flattened acromial (lateral) end
--Articulates with acromion process
--Acromioclavicular joint (AC)
when someone falls on an outstretched arm, where are they likely to have a fracture/break?
weak points: clavicle or wrist
when people fall on their shoulder, where will they have a fracture/break? why?
clavicle - it transmits force from the upper limb to the axial skeleton
what are the movements of the clavicle?
swinging strut, suspends scapula at corcacoid process . Allows scapula to "glide" on the thoracic wall (scapulothoracic joint)
what movements can the scapula do at the scapulothoracic joint?
upward rotation/downward rotation
characteristics of scapula structure? Think medial/lateral, anterior/posterior, superior/inferior
Medial, lateral, superior borders
--Superior transverse scapular ligament
Superior, lateral, inferior angles
Posterior surface divided by spine
--Supraspinous fossa (above spine)
--Infraspinous fossa (below spine)
Acromion- lateral end of spine
--Acromioclavicular (AC) joint
Anterior subscapular fossa: indented region
Coracoid process- looks like little thumb
Lateral surface bears glenoid fossa
--“Socket” for much larger humeral head
what two features create a foramen on the superior border of the scapula?
suprascapular notch and superior transverse scapular ligament
how does the acromion project?
anterior and laterally
where is the weight of the scapula and upper limb suspended?
center of balance: the strong coracoclavicular ligament- which is attached to the coracoid process on the anterior surface of scapula
how does the scapula and humerus counterbalance each other?
the balance of the coracoclavicular ligament but also the pull of the rhomboids against the weight of the limb.
posterior axio-appendicular muscles...O,I,A? What do they include?
Originate on axial skeleton
Insert on appendicular skeleton
Move or stabilize pectoral girdle and/or humerus
includes: superficial and deep extrinsic shoulder muscles
superficial extrinsic shoulder muscles
trapezius and lat. dorsi
deep extrinsic shoulder muscles
rhomboids (major and minor) + levator scapulae
scapulohumeral muscles: O,I,A. which muscles are included?
the intrinsic should muscles. O&I on appendicular skeleton. predominantly O on scapula and I on humerus
Act: on glenohumeral (shoulder) joint
-rotator cuff group
what muscles are in the rotator cuff group?
Deltoid features, O,I,A, Innerv.?
inverted triangle: anterior, middle, and posterior portions
O- lateral third clavicle, acromion, lateral scapular spine
I-deltoid tuberosity (prominence on humerus)
A-abducts arm after 15degrees
--posterior:extends (when adducted)
innveration:axillary nerve C5, C6 - terminal branch of brachial plexus
what abducts arm the first 15degrees?
Teres Major:general location, O,I,A, Innerv.
Forms posterior lateral boundary of axilla, runs very close to latissimus dorsi.
O-posterior surface of inferior scapular angle
I-intertubercular groove of humerus (posteromedial to latissimus dorsi)
Adducts & medially rotates arm
Innervated by lower subscapular nerve (C5, C6)
--(Collateral/preterminal branch of brachial plexus)
NOT THORACODORSAL NERVE
what does "teres" mean?
"round" - cylindrical shape of muscle
what type of baseball pitch would the teres major help in?
screwball, medial/internal rotation
which muscle is not part of the rotator cuff group but does serve to rotate the humerus?
what do the rotator cuff muscles do?
all 4 form a tendinous cuff around glenohumeral joint that stabilizes the oversized humeral head into undersized glenoid fossa - think of thumb and first three finger grabbing onto humeral- they form “ the cuff “
--3 of the 4 serve to rotate the humerus. (supra only ABducts)
--4 muscles provide tendinous support- support on all sides except inferiorly - plays a role in shoulder dislocation
what are the placement of the rotator cuff muscles in the finger model?
holding the head of the humerus with the palm as the glenoid fossa
ring: teres minor
supraspinatus: O,I,A, Inner,Blood?
I-greater tubercle (superior portion)
A: First 15° abduction of arm
Innervated: suprascapular nerve (C4-6)
---Collateral/preterminal branch of brachial plexus
-blood: suprascapular artery
what is the general location of the supraspinatus?
passes under the acromion and under the acromion ligament "bridge"
infraspinatus: O,I,A, blood?
O-infraspinous fossa of scapula
I-greater tubercle of humerus (posterior portion)
A: Laterally rotates arm
Innervated: suprascapular nerve (C5-6)
----Collateral/preterminal branch of brachial plexus
blood: suprascapular artery
what muscle aids in the curveball pitch?
infraspinatus (lateral rotation)