Mechanics: Unit 4 Upper limb + spine (online) Flashcards
what are the 5 parts of the upper limb?
shoulder girdle arm forearm wrist hand
What are the 3 synovial joints of the shoulder? what is the other articulation
glenohumeral
acromioclavicular
sternoclavicular
other is scapulothoracic (bone-muscle-bone)
What type of joint is the glenohumeral joint and what forms it?
synovial ball and socket formed from the humeral head and the glenoid fossa of the scapula
Is the glenohumeral joint stable? which structures help stability?
no the shallow glenoid fossa gives increased ROM but decreased stability so we need the glenoid labrum, joint capsule and rotator cuff muscles to stabilise
What movement do the rotator cuff muscles prevent? how?
anterior and posterior displacement of glenohumeral joint by pushing on the humeral head
inferior displacement
Which ligaments prevent upward movement of the scapula?
coracoclavicular ligaments
What structures prevent movement at the acromioclavicular joint?
thorax and mucle attachments
What is the only joint that connects the shoulder girdle to the trunk?
sternoclavicular
How does the clavicle elevate at the sternoclavicular joint?
elevates between 0-90 degrees: 4 degrees for every 10 degrees of arm elevation
past this minimal
What structure is the axis for rotation of the clavicle during elevation and depression?
costoclavicular ligaments
Why is the scapulothoracic articulation not a joint in the truest sense?
there is no direct ligamentous or bony attachment it is bone-muscle-bone
What two muscles form the scapulothoracic articulation?
serratus anterior
subscapularis
Where does serratus anterior originate and insert?
ribs 1-8/9
on scapula along vertebral border
Where does subscapularis originate and insert?
subscapular fossa
lesser tubercle of the humerus
What movement does serratus anterior do?
strong abductor in pushing/pulling
prevents scapula winging
What movement does subscapulris do?
medially rotates humerus
What are the 4 rotator cuff muscles?
subscapularis
infraspinatus
supraspinatus
teres minor
What are the main movements of the shoulder referred to?
shoulder elevation and depression
What is shoulder elevation called in the
a) sagittal plane?
b) frontal/coronal plane?
a) forward flexion
b) abduction
What is shoulder depression called in the
a) sagittal plane?
b) frontal/coronal plane?
a) backward extension
b) adduction
What are internal/external rotation of the shoulder?
rotation about the longitudinal axis of the humerus
What are horizontal flexion and extension?
with arms abducted parallel to the ground
flexion = move arm across body
extension = move arm behind body
What is the ROM of the shoulder for
a) backward extension?
b) abduction?
c) adduction
d) internal and external rotation?
e) horizontal flexion?
f) horizontal extension?
a) 60
b) 180
c) 75
d) 90 each
e) 135
f) 45
Which articulation of the shoulder is most prone to dislocation?
anterior dislocation of glenohumeral joint
When does anterior dislocation of glenohumeral joint occur?
heavy blow applied to abducted, horizontally extended arm
When the arm is in a position of abduction and horizontal extension what type of lever system are the shoulder and arm acting as?
1st class lever system
With the arm fully extended is the effort force working at a mechanical advantage or disadvantage at the acromion? What does this mean the resistance force must be?
MA
so a small effort force can cause dislocation
resistance force must be much larger (eg 10x)
What are the 3 articulations of the elbow joint?
humeroradial
humeroulnar
proximal radioulnar
What does the radial head articulate with on the humerus?
capitellum
What does the ulnar head articulate with on the humerus?
trochlea
Which articulations of the elbow allow
a) flexion/extension?
b) pronation/supination?
a) humeroradial and humeroulnar
b) proximal radioulnar
Where does the axis of rotation for flexion/extension of the elbow pass through?
trochlea
What is the ROM of flexion/extension of the elbow?
140 of flexion
0 of extension
What does the radial head rotate in during pronation/ supination of the elbow?
radial notch of the ulna
What structure binds the radius and ulna together at the proximal radioulnar joint?
annular ligament
What is the ROM of pronation/supination at the elbow ?
70 pronation
80 supination
How many degrees of flexion, pronation and supination at the elbow are required for daily activites at the elbow?
100 of flexion from 30-100 degrees
100 of pro/sup from 50 degrees
Which structure resistes A/P and P/A forces at the elbow?
olecranon
Which structures resist lateral and medial forces at the elbow?
collateral ligaments
Which collateral ligament of the elbow prevents
a) abduction?
b) adduction?
a) ulnar/medial
b) lateral
Which collateral ligament of the elbow is worse at its job? which structure helps it?
lateral
anconeus muscle
Why is the elbow joint subject to such high forces?
moment arm of muscles are much smaller than the moment arms of external forces so the muscle force must be very large
What is the radiocarpal joint between?
lunate and scaphoid and distal radius
What type of joint is the radiocarpal joint?
condyloid
What movements occur at the radiocalpar joint?
flexion-extension
abduction-adduction
circumduction
How do the triquetrum and ulna articulate?
via triangular intra-articular disc in ulnocarpal space
Which wrist joint allows for flexion more than extension?
midcarpal
Which wrist joint allows for extension more than flexion?
radiocarpal
How much ROM at the wrist for
a) flexion?
b) extension?
c) abduction?
d) adduction?
a) 80
b) 70
c) 15
d) 35
What is the most functional position for an immobilised wrist joint?
fixed extension of 15 degrees
What bones are in the hand?
5 metacarpals and 14 phalanges
What type of joint are the carpometacarpals?
saddle
Why is the 1st CMC joint so important? what bones does it lie between?
most freely moving to allow opposition of thumb
trapezium and 1st metacarpal
Where are the intermetacarpal joints?
in the joint capsules of the CMC, formed by articulations between proximal ends of adjacent metacarpals
What type of joint are the metacarpophalangeal joints?
condyloid
What movements does a
a) hinge joint
b) saddle joint
allow?
a) flexion/extension
b) flexion/extension, abduction/adduction
What type of joint are the interphalangeal joints?
hinge
How does the maximum amount of flexion at the metacarpo- phalangeal joint vary from finger to finger?
generally decreases from the fifth to the second joint. At the fifth joint (little finger) it is around 95 to 100 degrees and at the second joint (index finger) it is about 70 degrees.
What is metacarpophalangeal extension dependent on?
ligamentous laxity
Is flexion greater at the proximal or distal interphalangeal joints?
proximal
What is extension of the interphalangeal joint beyond neutral called?
hyperextension
Do the MCP joints allow more flexion in the thumb or the fingers?
fingers 90
thumb can be 30-90
What movements does the CMC of the thumb allow?
flexion
extension
abduction
rotation
How does movement of the wrist affect hand movement?
muscles that move the digits are found in the forearm but their tendons cross the wrist and as it moves it alters their functional length
Name the five regions of the spine.
cervical thoracic lumbar sacral coccygeal
How many vertebrae are found in the
a) cervical region?
b) thoracic region?
c) lumbar region?
a) 7
b) 12
c) 5
What is the spine made up of?
24 unfused vertebrae
sacrum (5 fused)
coccyx (4 fused)
What is the function of the intervertebral discs ?
bear and distribute load
restrain excessive motion
What forms the inner nucleus pulposus?
hydrophilic gel in a collagen matrix
What forms the annulus fibrosus? why is this helpful?
tough collagen form concentric layers of lamellae
alternating orientations help to resist bending and torsion loads
Describe C1
no body
ring within which an oval fossa articulates with axis
rotates about dens
Describe C2
superior articular process, the dens, joins to form a synovial joint with the oval fossa
What is each thoracic vertebrae attached to?
a pair of ribs
- head of rib to vertebral body
- tubercle of rib to transverse process
Why are the lumbar spine’s vertebral bodies bigger?
they are subjected to higher loads
What links the spine to the pelvic girdle?
sacrum
Which spinal region has
a) the most mobility?
b) the least mobility?
a) cervical
b) thoracic
What part of the spine is there no lateral bending?
occipital bone and C1
C1 and C2
How does rotation change along the spine?
greatest C1 and C2 then decreases down the spine
As the moment arm of the upper body weight increases does the loading on the spine increase or decrease?
increases
Is the load on the lumbar spine more when standing or sitting?
sitting
Give the carpal bones in order from right to left if looking anteriorly at the right hand
scaphoid
lunate
triquetrum
pisiform
(new row) traezium trapezoid capitate hamate
Where is the pisiform positioned? what significance does it have?
anteriorly to triquetrum (can be palpated)
it is the point of insertion of the flexor carpi ulnaris muscle and increases the lever arm
What does flexor carpi ulnaris do?
flexes and adducts the wrist
