Ch 9- shoulder girdle Flashcards
Shoulder girdle
Joint motions
- activities of scapula and clavicle, five muscles attach to the scapula, clavicle, or both, providing motion of the shoulder girdle
- elevation/depression, protraction/retraction (synonymous to abduction/adduction), upward and downward rotation
Shoulder joint
Motions of shoulder joint
- scapula and humerus, also called glenohumeral joint
- flexion, extension, hyperextension, abduction, adduction, medial and lateral rotation, horizontal abduction and adduction, nine muscles cross the joint and are the prime movers, has few ligaments
Sternoclavicular joint * (know all parts)
Joint motions
3 ligaments supporting this joint
- formed by articulation between manubrium and medial end of clavicle, this synovial joint provides the shoulder girdle with its only direct attachment to the trunk
- elevation/depression in frontal plane, protraction/retraction in transverse plane, rotation along the vertical axis of the bone
- sternoclavicular, costoclavicular, and interclavicular ligaments
Acromioclavicular joint * (know all parts)
Ligaments
- connects the acromion process of the scapula and the acromial end of the clavicle
- superior and inferior acromioclavicular ligaments, coracoclavicular ligament, and coracoacromial ligament
Scapulothoracic articulation
pg 131 The articulation of the anterior surface of the scapula against the posterior ribs
Scapulohumeral rhythm
describes the 2:1 ratio of normal motion between the glenohumeral and scapulothoracic joints; the first 30 degrees of shoulder joint motion is pure shoulder joint motion, after that, every 2 degrees of shoulder flexion or abduction that occurs, the scapula upwardly rotates 1 degree
humeral head-roll, glenoid fossa-glide
Clinical implication
any exercise performed in abduction or flexion should be done in the externally rotated position
Upper Trapezius
O- occipital bone, nuchal ligament on upper cervical spinous processes
I- outer third of clavicle, acromion process
A- scapular elevation and upward rotation
N- Cranial Nerve XI (accsessory)
Middle Trapezius
O- Spinous processes of C7 through T3
I- Scapular spine
A- scapular retraction (prime mover)
N- Cranial Nerve XI (accessory)
Lower Trapezius
O- Spinous processes of middle and lower thoracic vertebrae
I- Base of the scapular spine
A- scapular depression and upward rotation
N- Cranial Nerve XI (accessory)
Levator scapula
O- transverse processes of first 4 cervical vertebrae
I- vertebral border of scapula
A- scapular elevation and downward rotation
N- dorsal scapular nerve (C5)
Rhomboids
O- spinous processes of C7 through T5
I- vertebral border of scapula
A- scapular retraction, elevation, and downward rotation
N- dorsal scapular nerve (C5)
Serratus anterior
O- lateral surface of the upper eight ribs
I- anterior vertebral border of the scapula
A- scapular protraction and upward rotation
N- long thoracic nerve (C5, C6, C7)
Pectoralis minor
O- anterior surface, 3rd through 5th ribs
I- coracoid process of scapula
A- scapular depression, protraction, downward rotation, and tilt
N- medial pectoral nerve (C8, T1)
Prime movers of shoulder girdle: Retraction (combo of adduction and downward rotation)
Protraction (combo of abduction and upward rotation)
Elevation
Depression
Upward rotation
Downward rotation
Scapular tilt
- Middle trapezius, rhomboids
- serratus anterior, pectoralis minor
- upper trapezius, levator scapula, rhomboids
- lower trapezius, pectorals minor
- upper and lower trapezius, serratus anterior (lower fibers)
- rhomboids, levator scapula, pectoralis minor
- pectoralis minor
Postural influence:
Rounding of the shoulders
scapula protracted, rhomboids and middle trapezius (scapular retractors) in a chronically stretched position (these become weak and overstretched), pectoralis minor placed on slack and adaptively shortens over time
Rhomboids and levator scapula are ____ ____ the trapezius
directly underneath
Pectoralis minor is ___ to the pectoralis major
deep
Serratus anterior originates ____ and runs ____
anteriorly; posteriorly
Companion motions of shoulder girdle that must occur with shoulder joint motion
Shoulder joint: Shoulder girdle:
Flexion Upward rotation, protraction
Extension Downward rotation, retraction
Hyperextension Scapular tilt
Abduction Upward rotation
Adduction Downward rotation
Medial rotation Protraction
Lateral rotation Retraction
Horizontal abduction Retraction
Horizontal adduction Protraction
Muscles that form the FORCE COUPLE responsible for upward/downward rotation of scapula of shoulder girdle:
Scapula upward rotation*(more clinically relevant [around 28 mins shoulder comp])
Scapula downward rotation
-upper trapezius muscle pulls up, lower trapezius muscle pulls down, and lower fibers of serratus anterior muscle pull outward in a horizontal direction
-pectoralis minor pulls down, rhomboid muscles pull in, and levator scapula pulls up
downward rotation of scap must accompany extension of shoulder joint
Reversal of muscle action of shoulder girdle muscles and clinical significance
- shoulder girdle stabilized: lower trapezius and pectoralis minor can reverse their actions and assist in elevating the trunk, this is useful during crutch walking (they elevate the pelvis when the arms are stabilized)
- scapula stabilized: levator scapula can move the neck, assists the splenius cervicis in ipsilateral bending and rotation of neck
Clavicular fractures
most frequently broken bone in children, usually result from a fall on lateral aspect of shoulder or on outstretched hand, clavicle usually breaks in middle
around 3.30 anat shoulder girdle (something about the humeral head moves in relation to scapular motion)
around 19 mins she talks about scap winging and the serratus anterior and long thoracic nerve; “lonely lat” is to remember lateral pectoral nerve only innervates pectoralis major but medial pec nerve innervates BOTH pec minor and major
How does humeral head move relative to humeral movement? around 40 mins anat shoulder
It glides opposite to distal arm’s motion, if moving arm in anterior plane the humeral head is gliding posterior, if external rotation then humeral head is gliding anteriorly
What is force coupling?
Different muscles moving in different directions to produce same movement
What actions/muscles are involved with tucking in a shirt?
Actions: scapular depression, internal and external rotation, abduction and adduction, horizontal abduction and adduction, scapular elevation
Muscles: lower trap, latissimus dorsi, delts, upper trap, levator scapula
What actions/muscles are involved with hooking a necklace?
Actions: scapular retraction, horizontal abduction, force coupling of upward rotation of scap, shoulder flexion
Muscles: rhomboids, middle traps
