L: Scapular Muscles, Posterior Arm, and Shoulder Joint

other notes about teres major m.

"Lats little helper" People mix this up with teres minor. Really associate teres major with latissimus dorsi. Their action is virtually the same. Run in same location up as under axilla. Anterior view. Originates off the inferior angle of scapula on posterior side. Runs across GH joint ish and comes over the humerus. Have latissimus dorsi that attaches similarly. Attaches very closely to intertubercular sulcus or bicipital groove. Helps with medial rotation, adduction and extension. Latissimus dorsi does that too! Swimmer's muscle. V! the V is the lat dorsi hypertrophied and strong. Come over top, ADDuct, extending through. Both lat dorsi and teres major do that. If you just do "this" (ask her) it really helps. Disassociate teres major from ANYTHING rotator cuff.

ligaments of the acromioclavicular joint?

*acromioclavicular ligament* - strengthens AC joint superiorly *coracoclavicular ligaments* - anchors clavicle to coracoid process - prevents superior displacement of lateral end of clavicle - *conoid ligament* (posteromedial) - *trapezoid ligament* (anterolateral)

what are the ligaments at the GH joint?

*glenohumeral ligaments* - strengthen anterior aspect - superior/middle/inferior GH lig. *coracohumeral ligament* - part of fibrous capsule - strengthens superiorly *transverse humeral ligament* - holds the long head of the biceps tendon brachii in place *coracoacromial ligament* - STRONG superior support Each joint has ligaments associated with name. GH ligaments not visible in lab. Foldings in anterior joint capsule. Shoulder scope - can usually see these folds - but once they're embalmed you lose the subtle folding that makes up the ligaments. GH ligaments: there are 3 of them. Covering anterior surface of shoulder. The rest of the capsule around the shoulder is fibrous capsule with no true thickenings of ligamentous tissue. Coracohumeral ligament runs coracoid down to humerus. Not musch dynamic support. Transverse humeral on lateral humerus to other side. Coers up the bicipital groove and holding in the biceps brachii tendon. You can rupture this. Male gymnast see it! Coracoacromial connects coracoid process to acromion. Scapula to scapula. Strong superior support to GH joint. Don't dislocate superiorly partly due to this superior strength. Forms a passageway for one of our rotator cuff muscles to come through and attach to humerus. Not dynamic stability but does provide some if shoulder forced in weird positions. Nice examples of all of these except GH.

what is the quadrangular space?

*quadrangular space* transmits: - axillary n. - posterior circumflex humeral a. *triangular space* window: - circumflex scapular artery *triangular interval* window: - radial n. - profunda brachii a. (deep artery of arm) Very helpful thing to get comfortable with! Space called the quadrangular space in this it transmits the axillary nerve and posterior circumflex humeral artery. Know where and where not to approach the posterior shoulder. Helps in lab. Superiorly has teres minor and inferiorly is teres major. Laterally is border of humerus and medially is long head of triceps. Triangular space is important where we identify circumflex scapular artery. Makes easy location to know relationship that that's the only structure she could identify there. Superiorly is teres minor and inferiorly teres major and laterally is long head of triceps. Triangular interval is important because what's coming through is the radial n. and deep artery of arm. Running in radial groove is radial n. and deep artery of arm. Great place to tag on practical. Very important location from surgical perspective. Neurovascular compromise with humeral fractures you might see

what is the suprascapular notch and spinoglenoid notch?

*suprascapular notch* superior transverse scapular ligament - suprascapular nerve (below) - suprascapular artery (above) *spinoglenoid notch* inferior transverse scapular ligament compression in notch - posterolateral shoulder pain - atrophy of supraspinatus and infraspinatus mm. Anterior rim see little notch = suprascapular notch. The nerve gets to supraspinatous and infraspinatous. Interesting arrangement of neurovasculature. Over notch is little ligament to form bridge black arrow. It forms this bridge. Suprascapular nerve and artery like army and navy. Army stays on land and goes over the bridge. Navy in water and goes under bridge. How the vessel and nerve are coming. Go above and below this ligament to get into suprascapular fossa to innervate supraspinatous. To get down to infraspinatous they cannot magically go through bone but in lab you'll see there's a notch out in the spine. Go through spinoglenoid notch to get to the infraspinatous. Reflect back one side to see whole relationship. Inferior TSL place to protect. Need to care because here we can have compression syndromes. Achiness in deep shoulder. Atrphy (weakening) - can get compression injuries at suprascapular notch and spinoglenoid notch. Understanding how neurovasculature gets there has clinical relevance.

ligaments in the sternoclavicular joint?

- anterior and posterior sternoclavicular ligaments (strengthens A/P capsule) - interclavicular ligament (strengthens superiorly) - costoclavicular ligament (limits elevation of medial clavicle)

what are the scapulohumeral muscles? rotator cuff muscles?

- deltoid m. - supraspinatus m. * - infraspinatus m. * - teres minor m. * - subscapularis m. * - teres major m. SITS = rotator cuff muscles Everything we do from here on out has some dynamic effect on the joints we just presented! Scapulohumeral run from scapula to humerus. Stabilize GH joint or provide movement. Deltoid muscle is the shoulder muscle. Rotator cuff muscles. Made up of 4 muscles sometimes called the SITS muscles. Put 3 fingers on greater tubercle and one on lesser. Exactly how these 4 muscles insert/stabilize the shoulder. Teres major does very different things from minor.

triceps brachii m. action

- elbow extension (all heads) - long: extension, adduction of shoulder - lateral: recruited primarily against resistance

deltoid m. actions

- major abductor of the shoulder - anterior fibers also flex - posterior fibers also extend

true articulations in the shoulder girdle complex (synovial joints)?

- sternoclavicular (SC) joint - acromioclavicular (AC) joint - glenohumeral (GH) joint (true shoulder joint) scapulothoracic articulation = how scapula moves on thorax (wouldn't be able to go above 120 degrees -- we need the scapula to move!) not connected bony ring posteriorly, pelvis is! doesn't have as much mobility but really is a strong base of support. here we have mobility!

more notes triceps brachii m.

3 heads - only 1 head crosses the shoulder joint. This is posterior view. Have for extension of elbow. The long head is the head crossing shoulder joint. Originates on infraglenoid tubercle. Lateral head gives you the nice looking tricep. Just lateral posterior arm. Can feel it bulging if you extend your arm. Posterior humeral shaft but above radial groove. Then you have medial head (forgotten!). See extra bulge closer to elbow on medial side below wthe radial groove. All come to insert on olecranon of ulna = elbow point. All those muscles come down and has nice firm attachment on olecranon. Every head extends the elbow. One section crosses shoulder so long head does extension GH joint. Lateral head is the one when weight lifting it's the power section - isolated out. Really pushing/lifting that weight it's hyperrecruited. Not as much of a stability type of head. Better definition lateral side.

shoulder girdle?

= incomplete bony ring made up of the scapulae, clavicles, and connect to sternum Talk about joints then move up to ligaments/muscles. Sometimes hear something called shoulder girdle complex. Not just the shoulder glenoid. More complicated. Talking about each attachment of upper limb to allow us to have full motion when moving arm. Incomplete bony ring made up of scapulae and clavicles that connect anteriorly on sternum. Very superior sternum is called the manubrium. Scapula not a connected bony ring posteriorly. Pelvic girdle is the complete bony ring. Not as much mobility but really strong base of support to generate power. Power/stability pelvis. Here, NO! It's MOBILITY! Girdle still but not full ring. Really important difference between shoulder/pelvic girdles. Sternoclavicular joint. Acromioclavicular joint. True shoulder joint is the GH joint. Each of them are synovial. Each have a couple ligaments we'll be aware of. Great examples in lab! How scapula moves on thorax = scapulothoracic articulation. Wouldn't go above about 120 degrees maximum of shoulder abduction. Need scapula to move or motion is not good.

AC sprain

= separated shoulder Take fingers and push on lateral clavicle and if it bounches back and down + piano key sign if ligaments are stretched!!

more notes subscapularis

Big! On anterior side of scapula. Before we were on posterior side. Here it's a big muscle relatively speaking. Crosses GH on anterior surface and attaches on entire lesser tubercle. Internal rotation. Rotator cuff is a cuff. 3 muscles posteriorly and 1 anteriorly that "cups" the entire GH joint to stabilize it. Ant and post side work together to maintain stability. Upper and lower subscapular nerves. See these 2 little nerve branches coming in!

more notes on supraspinatus/infraspinatus?

Can bisect through supraspinatus to look at innervation. It goes out underneath coracoacromial ligament and attaches on the greater tubercle of humerus. This is the most superior attachmetn on greater tubercle.. This helps to initiate abduction. Can help pull arm out but deltoid much stronger and takes over. It doesn't shut off, firing but more as a stability/helper muscle. It still keeps working but just not the prime mover once up above those first few degrees. Infraspinatus is external/lateral rotation. Both of these muscles have the same innervation: suprascapular nerve.

bones of the upper limb

Clavicle, scapula, proximal humerus. Sit with shoulders back you should be able to palpate this bony landmark pushing out under clavicle. Sometimes you can even see it! Coracoid process is important because 3 muscles attach to it. Acromion is the most lateral portion of the scapula. Greater and lesser tubercle are CRITICAL because rotator cuff muscles attach! Little groove in between the tubercles. Look at lesser vs greater tubercle. Lesser on medial side close to axilla (armpit). Intertubercular groove (aka bicipital groove) - long head biceps brachii runs through it. Deltoid tuberosity - roughening of bone in most individuals on upper third of humerus. Lateral muscle of arm deltoid attaches here. Posterior view of scapula gives you a whole different perspective. Supraspinatus fossa -- there is a rotator cuff that goes right through this area. Spine of the scapula! Not in red boxes. The bony ridge on back walk out on spine to acromion. There is a fossa on anterior surface called the subscapular fossa. Very large rotator cuff comes off this! Surgical neck and anatomical neck. Anatomical neck red dot bottom. True neck embryologically because just below head. High predominance of fracturing humerus at surgical neck. Termed that surgical neck because we see surgery/fractures there often. Likely see fracture at surgical neck more than true anatomical neck. Radial groove on the humerus. Roughening of bone depending how much pressure. We'll come back to what runs there but neurovasculature runs along posterior humerus.

another view of glenohumeral joint

Envision looking at neighbor and arm is removed. Gives great perspective. Middle is glenoid fossa, articular surface. Humeral head articulates there. Darker blue rim is the labrum. Have tendon of long head of biceps brachii attaches up there. Continue to move out see synovial membrane is green and double layered capsule inner layer synovial lining and fibrous capsule outside. Then get bigger and bigger. Have rotator cuff on back side and front side closest to joint itself. Continue to move out you'll see bursa. Work out and have superficial muscles like deltoid pectoralis major latissimus dorsi. Other muscles coming around much more dynamic in movement. Move/stabilize the joint. 1 thing off throws off stability!

compartments of the arm?

Fascia of arm has deeper investing layers called IM septum. Separate arm anterior/posterior compartment. Thigh had A, P, M. here just 2. anteriorly flexing group. Posterior compartment is extending at shoulder/forearm. Antebrachial fascia comes out into forearm and palmar fascia similar to plantar aponeurosis. The palmar is much friendlier.

flattened deltoid?

Flattened deltoid. See the humeral head is anterior and inferior to glenoid dislocation GH joint.

more notes teres minor

Lateral border of scapula, runs closely with infraspinatus. Comes to greater tubercle more inferiorly. External/lateral rotation. You cannot functionally differentiate between teres minor and infraspinatus. Great Q in terms of difference of 2 external rotators teres minor axillary and infraspinatus suprascapular nerve.

scapula

Makes sense that there's a lot going on - very much there to guide motion of upper limb. Turn the scapula looking at it from the lateral side. Get a different perspective! The underbelly/lower resting point in the circle - muscle comes through supraspinous fossa to attach on humerus. Supraglenoid tubercle and infraglenoid tubercle. Glenoid fossa part of true shoulder joint. Has articular cartilage. Biceps brachii supra, triceps infra. Right: superior view looking down. Scapula not directly posterior on an angle! Angle of the scapula. At about 30-45 degrees. Posterolateral on thorax.

posterior view of rotator cuffs

Teres minor laterally on infraspinatus fossa. Teres major not rotator cuff!

AC sprain "separated shoulder"

The worse it gets the more ligaments are involved. Lateral image of lateral shoulder very separated. Radiograph see much more separated than it should be.

rotator cuff net anatomy picture

View from net anatomy little bit oblique looking in. see acromion spine. Humeral head covered in rotator cuff. Trapezius reflected back. Teres minor separated nicely. All come and attach on greater tubercle. See picture. If arm is removed looking in see what stabilizes the mobile joint since capsule not so great and bony articulation not either.

more notes on deltoid

We'll have some huge ones and some just barely there. Deltoid is one of the muscles where we need to know all 3 origins. Does multiple functions based on where fibers come from. Make U lay on lateral side of shoulder. Got it down. Insertion on those 3 sections? Trapezius!! Comes from the spine and it heads out laterally and its insertion on medial side of same bones the deltoid originates from. All of a sudden it helps to simplify those muscles/arrangements. Eeasy attachment on deltoid tuberosity. Color chalk humerus. ID bony feature. What muscle attaches here. Easy as long as you know name of tuberosity. Muscle rune anterior lateral posterior. Major action of all portions is abduction raising arms out to side. Anterior help to flex and posterior extend. Axillary nerve! Above armpit.

deltoid m. origin

anterior: lateral 1/3 of clavicle middle: acromion of scapula posterior: spine of scapula

anconeus m. action

assists triceps brachii m.

deltoid m. innervation

axillary n. (C5, C6)

teres minor innervation

axillary n. (C5, C6) remember, it's right around the armpit

deltoid m. insertion

deltoid tuberosity of humerus

teres minor action

external (lateral) rotation of shoulder

acromioclavicular joint

includes - acromion process and lateral end of clavicle - synovial, gliding joint - articular disc - loose fibrous joint capsule Injured quite often! Acromion and LATERAL clavicle now. Gliding joint. Tip of shoulder. Wiggle arm, feel a little bit of shifting/rotating and gliding between bones. Not super obvious. Quite mobile! Pretty loose joint capsule. Disc to help absorb force. Great image bottom. Box is loose ligament/capsule with disc in middle that's quite mobile. Thickening of joint capsule. Pin ligament and she prefers you say acromioclavicular ligament. Move on and there are also other ligaments. Not directly over the joint itself = accessory ligaments. Actually more important to joint stability than acromioclavicular ligament itself. Coracoclavicular ligament really anchors the lateral end, prevents superior displacement or lateral elevation of clavicle. Trapezoid ligament and conoid ligament. We have really good examples of this in lab, easy to distinguish. Conoid more medial/posterior. Trapezoid more lateral and more anterior. You'll see that in lab!

glenohumeral joint

includes: - synovial, ball and socket joint - very mobile, but unstable articulation: - large humeral head - shallow glenoid cavity (fossa) -- deepened by *glenoid labrum* loose fibrous joint capsule strengthened by rotator cuff mm. True shoulder joint! Very complex. Doesn't do it justice but we'll cover quite a bit of it. Really our true shoulder. GH joint. Sacrificed stability for mobility. Lots of things have to make sure we don't dislocate/hurt it. Large humeral head and shallow glenoid fossa. Glenoid labrum! Labrum is either acetabular or glenoid. Cannot just say labrum because 2 very different ones in the body. The fibrous capsule around the shoulder is very loose, not very effective. The shoulder relies on muscles to help stabilize it. Muscular group rotator cuff has a lot to do with stability. Lots going on to keep shoulder in right relationship.

teres major m. origin

inferior angle of scapula

teres minor insertion

inferior facet of greater tubercle of humerus

infraspinatus origin

infraspinous fossa

supraspinatus action

initiates abduction of the arm (assists deltoid m.)

teres major m. action

internal (medial) rotation, ADDuction, and extension of shoulder

subscapularis m. action

internally (medially) rotates shoulder

teres major m. insertion

intertubercular sulcus (bicipital groove) of humerus

infraspinatus action

lateral (external) rotation of shoulder

teres minor origin

lateral border of scapula

anconeus m. origin/insertion

lateral epicondyle of humerus to olecranon

subscapularis m. insertion

lesser tubercle of humerus (lesser is more anterior which is where this muscle is)

triceps brachii m. origin

long head -- infraglenoid tubercle lateral head -- posterior humeral shaft, above radial groove medial head -- posterior humeral shaft, below radial groove

teres major m. innervation

lower subscapular n. (C5, C6)

infraspinatus insertion

middle facet of greater tubercle of humerus

scapulohumeral rhythm

movements - sternoclavicular (SC) joint - acromioclavicular (AC) joint - glenohumeral joint - *scapulohumeral rhythm* = 3 degrees of elevation (2 degrees at GH joint, 1 degree at scapulothoracic articulation) Clinical correlate. Scapula so important for full motion of arm. If it doesn't move we get stuck. For every 2 degrees of humeral or GH movement the scapula has to move 1 degree. Works quite well! 2:1 ratio of GH movement:scapular movement. Get through true 180 degrees of Abduction. Without scapula that won't happen.

triceps brachii m. insertion

olecranon of ulna

anconeus m. innervation

radial n. (C5-T1)

subscapularis m. origin

subscapular fossa

supraspinatus insertion

superior facet of greater tubercle of humerus

innervation of supraspinatus and infraspinatus mm.?

suprascapular n. (C5, C6)

supraspinatus origin

supraspinous fossa

what is the sternoclavicular joint?

the only articulation between the upper limb and axial skeleton includes: - sternal end of clavicle, manubrium of sternum, 1st costal cartilage - synovial, saddle joint - articular disc Another critical joint in connecting upper limb to axial skeleton! Only true attachment of upper limb to axial skeleton. Clavicular fractures common, fracturing one of the only bones connecting arm to axial skeleton. Deeper view on left. Superficial right. CT 3D reconstruction below. Joint includes the sternal/medial end clavicle, manubrium of sternum, and the 1st costal cartilage. Ribs come in anteriorly and connect to sternum with cartilage piece. Ligament attaches to stabilize joint. Synovial joint = saddle joint. Little articular disc in there in middle that's thought to help stabilize the bones together, absorb some of the forcees that run through that joint if you fall. Can help to absorb some of the forces. Nothing hugely noticable on dissection. Ligaments: count at least 1 ligament with name of joint. Technically anterior and posterior sternoclavicular ligaments. Just capsular thickenings not the pluckable LCL of knee or anything like that. It strengthens the joint! Don't want clavicle to move too far anterior/posterior so it limits that motion. Interclavicular doesn't do a TON but helps to reinforce/strengthen the joint superiorly. Not a lot in terms of true dynamic joint stability. Costoclavicular ligament is the inferior ligament. Big role in stability. Coming from below it on costal cartilage. Its job is to hold down the clavicle. Extra force on clavicle, ligament engages so clavicle can't pop up. Little more dynamically involved! Not a good example in lab. Ligaments intuitive! Area of written test question.

subscapularis innervation

upper and lower subscapular nn. (C5, C6)