Test 2 Flashcards
SCJ anterior/posterior ligaments do what?
Check ant/post translation
7 joint involved in shoulder elevation
AC GH SC ST thoracic spine Costotransverse/ costovertebral Costochondral
SCJ interclavicular ligaments do what?
Checks clavicular depression
SCJ costoclavicular ligament
Anterior and posterior fibers
Limits elevation
Contributes to inferior gliding of clavicle
SCJ type of joint
Saddle shape, plane synovial
SCJ frontal plane
Frontal plane- convex on concave
Elevation and depression
SCJ elevation
48 degrees
SCJ depression
10 degrees
- you don’t depress often
SCJ in transverse plane
Concave on convex
Protraction
Retraction
SCJ protraction
20 degrees
SCJ retraction
30 degrees
SCJ in sagittal plane
Saddle shape
Posterior rotation
Anterior rotation
SCJ posterior rotation
50 degrees
SCJ anterior rotation
<10 degrees
ACJ joint
Capsule is weak
Superior and inferior ligaments
Superior checks distal clavicle from moving posteriorly
ACJ coracoclavicular ligament- Conoid
- resist distal clavicular superior motion
- limit upward rotation of scapula
- posteriorly rotates clavicle
ACJ coracoclavicular- trapezoid
Limit posterior displacement of clavicle
Limits upward rotation of scapula
Posteriorly rotates clavicle
ACJ coracoacromial ligament
Roof for GHJ
protects subacromial bursa and RTC
What kind of joint is the ACJ
Planar
Movement of ACJ
Minimal
20-40 degrees anterior/posterior tilting
30 degrees upward/downward rotation
30 degrees IR/ER
Scapulothoracic joint positioning
30-45 degrees coronal plane
10-15 degrees anteriorly tilting
10 degrees upwardly rotated
Scapulothoracic joint upward rotation mobility
60 degrees
Axillary line
- coupled with posterior rotation SCJ
Coupled with clavicular elevation
Scapulothoracic joint elevation and depression occurs where
At SCJ
Scapulothoracic joint protraction retraction occurs where
At SCJ
Scapulothoracic joint IR/ER and anterior/posterior tilting occurs where
At ACJ
Scapulo-humeral rhythm
- maintain optimal alignment of the glenoid and humeral head
- increase ROM available in elevation
- maintain optimal length-tension relationship for the scapulo-humeral muscles
- -> minimize activity insufficiency
What effect does gravity have on GHJ
Fall-out
What prevents subluxation of GHJ
Labrum
Joint capsule acts as suction
RTC
amongst others
Labrum does what to GHJ
Increases depth by 50%
GHJ capsule
Loose anteriorly and inferiority
Tight superiorly
Creates intrarticular pressure
Superior GH ligament
1) labrum to humerus connects with coracohumeral ligament
2) anterior and inferior stability
Middle GH ligament
- superior anterior labrum to anterior humerus
- anterior joint stability up to 60 degrees abduction
Inferior GH ligament
- 45 degrees abduction resists inferior translation
- ER resists anterior translation
- IR resists posterior translation
GHJ coracohumeral ligament
Limits inferior translation
Humeral head orientation
Medially
Superiorly: 130-150 degrees
Posteriorly: 30 degrees
GHJ mobility
Convex on concave
Describe the GHJ motions that occur with abduction
External rotation
GHJ motions that occur with scapular plane
Less ER
GHJ motion that occurs with flexion
Internal rotation
Scapulo humeral rhythm movements of humerus and scapula
Elevation of the humerus
Upward rotation and posterior tilting of scapula
2:1 ratio (GHJ:STJ)
4 joints getting to 180 degrees
SCJ-40 elevation and upward rotation
ACJ- minimal motion
STJ- 60 degrees upward rotation
GHJ- 120 degrees elevation
How many muscles act on the shoulder during elevation?
18 Biceps Triceps Deltoid x3 Traps x3 SITS rhomboids x2 Levator scapulae Serrated anterior Lats Teres major
Upward scapular rotators
Upper trapezius
Middle trapezius
Lower trapezius
Serratus anterior- prime mover
Compression and joint stabilization muscles of shoulder
Infraspinatus
Teres minor
Subscapularis
Supraspinatus- some elevation too
angle of pull causes what on humerus?
Compression and spin
Glenohumeral elevation
- Supraspinatus: test in scapular plane. Most active 0-60 degrees abduction, scapula starts moving at 60
- Deltoid: prime elevator for flexion, assist abduction after 15 degrees. More superior force
Supraspinatus lever arm
Much better lever arm than deltoid, larger axis of rotation so get more force
Deltoid turns off up top because moment arm is smaller because of active insufficiency
Deltoid and Supraspinatus during arm elevation
Deltoid has poor ma during early elevation
Supraspinatus has longer ma during elevation
Deltoid ma improves in mid-range
Deltoid provides greater abduction force than Supraspinatus
Deltoid and rotator cuff during arm elevation
Deltoid causes superior glide of humerus- impingement
Cuff causes inferior glided
Shoulder depression muscles in weight bearing
Latissimus Doris
Pectoral is major
- need to work because they are counteracting upper trap. Ys Ts Ws
What muscle prevents scapular internal rotation
Rhomboids
- serratus anterior does the IR of scapula
Teres major and internal rotation
Extends humerus, if teres major is activated without the rhomboids, scapula would internally rotate
Shoulder muscles for scapular depression and abduction
Pec minor
GIRD
Glenohumeral IR deficit
-a loss of IR of 20 degrees or more compared to contralateral side
Seen primarily in baseball athletes and overhead throwing. Huge difference in dominant vs. non dominant hand
Factors in shoulder overuse injuries
Impingement
RTC tears
SLAP tears
Causes of GIRD
Humeral retroversion (so sits more posterior in GHJ)
Throwing causes ER torque
Humeral head sits posteriorly on glenoid
GIRD measurements
Total motion ER + IR= total motion >5 degree loss in total motion Increase risk of injury Greater number of lost games
Causes of serratus anterior weakness
Long thoracic nerve palsy
Disuse
Scapular winging in flexion
Because serratus anterior is not holding scapula
- could be because pec minor internally rotates the scapula from the front and if it’s stronger than the serratus then winging will occur
Causes of upper trap weakness
Spinal accessory nerve palsy (SNAP) Positives scapular flip Trapezius atrophy Depressed scapula Trap weakness Limited shoulder abduction
Patient has weakness in shoulder flexion, which muscle is it?
Serratus anterior
Serratus anterior vs. trapezius weakness
Winging vs. flipping out
Upper trapezius weakness
Cannot abduct
Downwardly rotate and scapula flips out
Check medial border of scapula to see the downward rotation
Upper trapezius overuse
Decrease upward rotation of scapula
Increase shoulder impingement
Causes of rotator cuff weakness
Overuse Surgery Disuse Injury C5 rediculopathy
Rotator cuff weakness signs
Shoulder hike, cannot ER so cannot abduct
To abduct the arm you must:
Externally rotate the arm
Shoulder subluxation
no deltoid or RC
upper trap atrophy
posture is #1
How can we improve shoulder subluxation
muscle strength
posture
upper trap
RC muscles
The elbow complex
- designed to improve mobility for the hand in space
- provide stability for the hand during forceful movements
- consists of elbow joint (humeroulnar or humeroradial) and proximal and distal radioulnar joints
The elbow joint
- compound joint; modified or loose hinge joint
- functions as a modified or loose hinge joint
how many degrees of freedom is the elbow joint
1 degree of freedom
- flexion and extension in the sagittal plane
- slight axial rotation and side to side motion of the ulna during flexion and extension: therefore a modified or loose hinge joint
In what position is the elbow joint close packed?
- extension
close packed position
bones and ligaments and position of least mobility
open packed position
bones and ligaments are in most mobile position
- The more swelling in a capsule, the more you want the joint to be in open packed position
What kind of joint is the radius when attached to the humerus?
spin joint so we can pronate and supinate
Elbow in flexion
- has a larger surface area to provide joint surfaces and more stability in weight bearing
Elbow joint capsule
- single joint capsule for 3 joints
- capsule fairly loose and weak anteriorly and posteriorly
- Reinforced with ligaments medially and laterally
- in flexion and extension bone sits really well but not side to side
most common side for baseball injury in the elbow
medially
elbow joint medial ligaments
- flexors on medial side to stabilize
- proximal MCL fused with common flexor tendon
- limits extension at end range
- guides joint motion throughout flexion
- provides some resistance to longitudinal distraction
- pronation
- Main restraint 20-120 degrees; not 20-0 because bony component takes over
primary restraint of valgus stress on elbow
anterior MCL at 20-120 degrees of elbow flexion