BMS271 - Shoulder Flashcards
1
Q
Shoulder Complex
A
The shoulder complex consists of four articulations all of which contribute to the mobility of the upper limb
- Scapulothoracic joint (ST)
- Sternoclavicular joint (SC)
- Acromioclavicular joint (AC)
- Glenohumeral joint (GH)
2
Q
Scapulothoracic Joint (ST)
A
Not a true anatomical joint, scapula glides over thorax
- No joint capsule, synovial membrane, fibrous tissue or articular cartilage
- Scapula and rib cage separated by layers of muscle and connective tissue
- Scapulothoracic motion linked with AC and SC joint motion
- Elevation/depression
- Protraction/retraction
- Upward/downward rotation
- Scapular motion increases upper limb ROM
- Contact between scapula and thorax maintained by musculature
- Movement of scapula ensures glenoid fossa is in best position for mobility of upper limb
- Stability of scapula is also important for rolling and sliding of humeral head on glenoid cavity
- During various tasks the scapula needs to be mobile or stable and is ideally always in good contact with the thorax: all this depends on the action of the muscles attached to the scapula
3
Q
Sternoclavicular Joint (SC)
A
- Only point of direct attachment of pectoral girdle and axial skeleton
- Saddle synovial joint (acts like ball and socket)
- Joint capsule contains articular disk (fibrocartilage)
- Joint supported by anterior and posterior sternoclavicular ligaments, the interclavicular ligament and costoclavicular ligament
- Allows elevation/depression, protraction/retraction and rotation of the clavicle
- Movement of the clavicle is linked to movement of the scapula
4
Q
Sternoclavicular Joint Articular Disk
A
- Separates joint into two separate synovial cavities
- Improves contact b/w incongruent bony surfaces
- Attached to clavicle, sternum, 1st costal cartilage and joint capsule = provides stability
- Acts as hinge to provide mobility
- Allows rotation of clavicle 30-55° posteriorly from neutral
- Provides shock absorption
5
Q
Acromioclavicular Joint (AC)
A
- Plane synovial joint
- Joint contains disk of variable size/shape
- Weak capsule supported by the acromioclavicular ligament (reinforced by trapezius tendon)
- Allows protraction/retraction of the scapula around a vertical axis ie glenoid fossa ends up facing anteriorly when protracted
- Also allows tipping of the scapula ie scapula is elevated and must adhere to thorax, which is curved; results in inferior angle of scapula protruding
6
Q
Coracoclavicular Ligament
A
Has two parts: conoid and trapezoid ligaments
Both parts support the AC joint and allow the rest of the upper limb to be suspended from the clavicle
7
Q
Trapezoid ligament
A
- lateral portion of Coracoclavicular Ligament
- quadrangular
- nearly horizontal
- prevents overriding and narrowing of angle b/w clavicle and scapula (from above)
8
Q
Conoid ligament
A
- medial portion of Coracoclavicular Ligament
- triangular
- nearly vertical
- restricts vertical movement of clavicle,
- prevents widening of the angle b/w clavicle and scapula
9
Q
Glenohumeral Joint
A
- Shallow ball and socket joint
- Glenoid fossa slightly deepened by glenoid labrum, a rim of fibrocartilage
- Neither surface is perfectly spherical,
- incongruence means that head of humerus may roll and/or slide
- With upper limb at rest coracohumeral ligament and superior capsule resist gravity whilst the rest of the capsule and glenohumeral ligaments are relaxed
- During abduction and lateral rotation the joint capsule twists and tightens, reinforced by the anterior, middle and inferior glenohumeral ligs. Closed packed position
- GH joint stability relies heavily on muscular support
- The glenohumeral joint allows flexion/extension, abduction/adduction and medial and lateral rotation
- The coracoacromial arch (coracoid process, acromion and coracoacromial ligament) is superior to the GH joint and prevents impact trauma and superior dislocation
- Subacromial bursa allows free movement of structures beneath the arch
10
Q
Closed packed position of joint
A
= maximal congruence
= maximal tension in joint capsule
= maximal stability
11
Q
Scapulohumeral Rhythm
A
Shoulder complex capable of 180 ° of abduction
- GH component : ST component = 2:1
- That is; the glenohumeral joint contributes roughly 120 ° of motion, and the scapulothoracic contributes 60°
- Much variation b/w individuals
- Scapula component small during first 30°
- Full abduction requires mobility of the upper thoracic and cervical regions of the spine
12
Q
Pectoralis Major
A
Attachments:
- clavicular head: medial half of clavicle
- sternocostal head: anterior surface of sternum, costal cartilages 1-6
- intertubercular sulcus
Actions:
- adducts and medially rotates humerus,
- draws scapula anteriorly and inferiorly
- clavicular head alone flexes humerus,
- sternocostal head alone extends humerus from flexed position
Innervation:
lateral and medial pectoral nerves (clavicular head C5, C6, sternocostal head C7 and C8, T1)
13
Q
Pectoralis Minor
A
Attachments: - ribs 3-5 near costal cartilages - coracoid process Actions: - stabilises scapula by drawing it anteriorly and inferiorly Innervation: - medial pectoral nerve (C8 and T1)
14
Q
Subclavius
A
Attachments:
- junction of 1st rib and 1st costal cartilage
- inferior surface of middle third of clavicle
Actions:
- anchors and depresses clavicle
Innervation:
- nerve to subclavius (C5 and C6)
15
Q
Serratus Anterior
A
Attachments: - lateral aspect of ribs 1-8 - medial border of scapula Actions: - protract scapula, - rotate scapula superiorly (lower fibres), - hold scapula to thorax Innervation: - long thoracic nerve (C5, C6 and C7)
16
Q
Trapezius
A
Attachments: - superior nuchal line, - external occipital protuberance, - nuchal ligament - spinous processes C7 - T12 - lateral third of clavicle, - acromion - spine of scapula Actions: -descending part elevates scapula, - ascending part depresses scapula, - central fibres retract scapula, - descending and ascending together rotate glenoid cavity superiorly Innervation: - accessory nerve (XI) and C3-4
17
Q
Latissimus Dorsi
A
Attachments: - spinous processes of T7-12, - thoracolumbar fascia, - iliac crest, - ribs 9-12 - intertubercular sulcus Actions: - extends, - adducts and - medially rotates humerus Innervation: - thoracodorsal nerve (C6, C7 and C8)
18
Q
Levator Scapulae
A
Attachments: - transverse processes of C1-C4 - medial border of scapula Actions: - elevate scapula, - rotate scapula inferiorly Innervation: - dorsal scapular nerve (C5), C3 and C4
19
Q
Rhomboid Major
A
Attachments: - major: T2 - T5 - medial border of scapula Actions: - retract scapula, - rotate glenoid cavity inferiorly Innervation: - dorsal scapular nerve (C4 and C5)
20
Q
Rhomboid Minor
A
Attachments: - minor: C7 and T1 - medial border of scapula Actions: - retract scapula, - rotate glenoid cavity inferiorly Innervation: - dorsal scapular nerve (C4 and C5)
21
Q
Deltoid
A
Attachments: - lateral third of clavicle, - acromion - spine of scapula - deltoid tuberosity of humerus Actions: - anterior fibres flex and medially rotate arm, - posterior fibres extend and laterally rotate arm, - all fibres are active in abduction Innervation: - axillary nerve (C5 and C6)
22
Q
Supraspinatus
A
Attachments: - supraspinous fossa of scapula - greater tubercle of humerus Actions: - initiates abduction, - maintains apposition of head of humerus and glenoid cavity during motion Innervation: - suprascapular nerve (C4, C5 and C6)
23
Q
Infraspinatus
A
Attachments: - infraspinous fossa - greater tubercle of humerus Actions: - lateral rotation of humerus, - maintains apposition of head of humerus and glenoid cavity during motion Innervation: - suprascapular nerve (C5 and C6)
24
Q
Teres Minor
A
Attachments: - lateral border of scapula - greater tubercle of humerus Actions: - lateral rotation of humerus, - maintains apposition of head of humerus and glenoid cavity during motion Innervation: - axillary nerve (C5 and C6)
25
Q
Subscapularis
A
Attachments: - subscapular fossa - lesser tubercle of humerus Actions: - medial rotation of humerus, - maintains apposition of head of humerus and glenoid cavity during motion Innervation: - upper and lower subscapular nerves (C5, C6 and C7)
26
Q
Teres Major
A
Attachments: - inferior angle of scapula - intertubercular sulcus of humerus Actions: - adducts and medially rotates humerus Innervation: - lower subscapular nerve (C5, C6)
