Unit 2 - The Shoulder Joint Flashcards
(38 cards)
Describe the SC joint Joint classification Articulations Axis of movement Joint capsule Intracapsular Structures Extracapsular Structures
Joint classification Synovial saddle joint Axis of movement Triplanar Articular Surfaces a) Sternal (medial) end of clavicle • Covered by fibrocartilage • Convex superior to inferior • Concave anterior to posterior
b) Clavicular notch of the sternum
• Covered in hyaline cartilage
• Reciprocally concavo-convex
c) Costal cartilage of 1st rib.
Joint capsule
• Fibrous capsule surrounding joint
• Attached to articular margins of clavicule and sternum
• Weak inferiorly
• Supported anteriorly and posteriorly by ligaments
Intracapsular structures
Intra-articular Disk O: Superior border of the sternal end of the clavicle I: Costal cartilage of the 1st rib. A: • Improves congruency • Shock absorption and force dissipation • Stabilization of SC joint
Extracapsular Structures
Ligaments 1. Anterior SC ligament O; Medial clavicle (anterior) I: Runs obliquely infero-medially to the sternum A: Reinforces anterior aspect of joint capsule
- Posterior SC ligament
• Mirrors anterior sternoclavicular ligament on posterior side
• Not as strong
O:
Medial clavicle (posterior)
I:
Runs obliquely downwards and medially to the sternum
A:
Reinforces posterior aspect of joint capsule
3. Interclavicular ligament O Sternal end of the clavicle I: Sternal end of the contralateral clavicle A: • Limits scapular depression.
4. Costoclavicular ligament • Very strong extracapsular ligament O: Inferior surface of medial clavicle I: Costal cartilage of 1st rib A: Limit elevation of clavicle, and to prevent excess ant/post movement of medial end of clavicle.
Describe the AC joint Joint classification Axis of movement Articulations Joint capsule Ligaments
The Acromioclavicular Joint
Joint classification
Synovial plane joint
Axis of movment
Triplanar
Articular surfaces
Reciprocally shaped oval facets on:
• Lateral end of clavicle (slightly convex)
• Anteromedial tip of the acromion process (slightly concave)
• Both surfaces covered in fibrocartilage
• Wedge-shaped intra-articular disc.
Joint capsule
• Loose, fibrous capsule attaching to joint margins
Ligaments
- Superior and inferior AC ligaments
• Thickenings of the capsule above and below the joint - Coracoclavicular Ligament
• 2 parts (conoid and trapezoid)
• Anchor lateral end of clavicle to coracoids process to prevent upward displacement - Conoid
• Posteromedial, fan-shaped
• Attaches from ‘elbow’ of coracoids process to conoid tubercle on inferior clavicle
• Restricts anterior movement of scapula - Trapezoid
• Anterolateral, flat, quadrilateral band
• Stronger than the conoid ligament
• Attaches from superior surface of coracoids process to trapezoid line on inferior aspect of clavicle (antero-lateral to the conoid tubercle)
• Restricts posterior movement of scapula
Describe scapular elevation and scapular depression at the SC joint and AC joints
SC Joint
Scapular Elevation
• Clavicle rolls superiorly, glides inferiorly
• Axis = Saggital plane
• ROM = 60°
• Limited by: Tension in costoclavicular ligament and subclavius.
Scapular Depression • Clavicle rolls inferiorly, glides superiorly. • ROM = 60° Limited by Interclavicular ligament Intra-articular disc
AC JOINT Scapular Elevation • Acromion glide superiorly (moving concave on fixed convex) • Axis = Saggital • ROM = 15° Limited by: • Tension in coracoclavicular ligaments
Scapular Depression • Acromion glides inferiorly • ROM = 15° Limited by: • Coracoid process meeting inferior clavicle.
Describe scapular protraction and retraction at the SC and AC joint?
SC Joint
Scapular Protraction
• Clavicle roll and glide anteriorly
• Axis of movement = vertical through costoclavicular ligament
• ROM = 35°
Limited by:
• Costoclavicular and posterior SC ligaments
Scapular Retraction • Clavicle rolls and glides posteriorly • ROM = 35° Limited by: • Costoclavicular and anterior SC ligaments
AC JOINT Scapular protraction • Acromion glides anteriorly • ROM = minimal Limited by: • Posterior AC joint capsule • Both coracoclavicular ligaments
Scapular retraction • Acromion glides posteriorly • ROM = minimal Limited by • Anterior AC joint capsule • Trapezoid ligament
Describe scapular lateral rotation and medial rotation at the SC and AC joint?
SC JOINT Scapular lateral rotation • Clavicle rolls superiorly, glides inferiorly • ROM= 60° Limited by: Tension in costoclavicular ligament Subclavius
Scapular medial rotation • Clavicle rolls inferiorly, glides superiorly • Rom = 60° Limited by Interclavicular ligament Intra-articular disc
AC JOINT
Scapular lateral rotation
• Acromion laterally rotates in relation to clavicle at AC joint
• Axis of movement through conoid ligament and AC joint
• ROM = 30°
Limited by
• Both parts of coracoclavicular ligament
Scapular medial rotation
• Acromion medially rotates back to original position
• ROM = 30°
Limited by:
• Both parts of the coracoclavicular ligament
What is the scapulohumeral rhythm? At what degree does scapular lateral rotation occur, and at what ratio?
Scapulohumeral rhythm
• Coordinated rhythm between scapula and humerus during shoulder flexion and abduction
• Initial 25-30° of flexion/abduction from GH joint alone
• After 30°, scapular lateral rotation occurs with GH movement (1:2 ratio) to permit full ROM.
Describe the glenohumeral joint Joint classification Axis of Movement Articulations Joint capsule Intracapsular Structures Extracapsular Structures Movements
Joint classification
• Synovial ball and socket
Axis of movement
• Triplanar
Articulations
a) Head of Humerus
• Hemispherical and covered in hyaline cartilage.
• Faces medially, superiorly, and posteriorly
b) Glenoid Fossa
• Situated on lateral aspect of scapula
• Pear-shaped and covered w/hyaline cartilage.
• Faces antero-laterally
• Poor congruency of articular surface (1:4 size ratio fossa:head)
c) Glenoid Labrum
• Fibrocartilage covering that deepens the glenoid fossa
• Attached to articular margins
\Joint capsule • Cylindrical sleeve that passes from glenoid fossa to humerus • Lax structure Synovial Membrane • Lines inside of capsule • Forms subscapular bursa anteriorly • Forms infraspinatus bursa posteriorly • Attached to long head of biceps. Intracapsular structures
- Subacromial (deltoid)
• Non-communicating bursa
• Separates coracoacromial arch and deltoid muscle from superolateral aspect of shoulder joint| - Long head biceps tendon
Extracapsular structures
Glenohumeral ligaments (3) • All provide anterior stability to GH joint • Thickenings in anterior capsule 1. Superior 2. Middle 3. Inferior Three accessory ligaments 4. Coracohumeral 5. Coracoacromial 6. Transverse humeral
1. Superior GH ligament O: Superior surface of glenoid labrum I: Superior surface of lesser tubercle
2. Middle GH ligament O: Inferior to superior GH ligament origin I: Anterior aspect of lesser tubercle, inferior to subscapularis insertion
3. Inferior GH ligament O: Glenoid fossa I: Antero-inferior part of anatomical neck of humerus
4. Coracohumeral ligament O: Lateral border of coracoids process, divides at intertubercular groove I: Two tubercles of humeral head
A:
Prevents inferior displacement of the humerus
5. Coracoacromial Ligament • Strong triangular ligament O: Coracoid process I: Acromion process A: • Creates fibro-osseus arch • Prevents superior displacement of humerus • Helps dissipate forces transmitted upwards through humerus
6. Transverse Humeral ligament O: Greater tubercle I: Lesser tubercle at upper end of bicipital groove A: Holds long head of biceps in place
Movements
Flexion = 180° (60° made possible by lateral rotation of scapula)
• Spin and inferior glide necessary for full flexion
Limited by:
Tension in extensors muscle
Posterior capsule
Extension = ~90° (last 20° made possible by scapula)
• Spin
Limited by:
• Tension in shoulder flexors.
• Glenohumeral ligaments
• Anterior capsule
• Contact of the greater tubercle with the coracoacromial arch
Abduction = 180° (60° made possible by lateral rotation of scapula)
• Superior roll, inferior glide
Limited by:
• Contact between greater tubercle and coracoacromial arch
• Tension in rotator cuff muscles / shoulder adductors
Adduction = 30°
• Inferior roll, superior glide
Limited by:
• Contact with trunk
External rotation = 80° • Posterior roll, anterior glide • Spin (when arm is 90°) Limited by: • Tension in internal rotators • Anterior capsule
Internal rotators = 100-110° (when arms goes behind trunk)
• Anterior roll, posterior glide
• Spin (when arm @ 90°)
Limited by:
• Tension in the lateral rotators and posterior capsule
What are the factors contributing to the stability of the GH joint (3) and the instability of the GH joint (3)?
GH is unstable
• Incongruency and poor size ratio of articular surfaces
• Lax capsule
• Weak ligaments
GH is stable
• Glenoid labrum
• Long head of biceps tendon
• Rotator cuff muscles and larger overlying muscles.
What are the movements at the scapula at GH joint during medial and lateral rotation?
Scapular lateral rotation
• Glenoid fossa turns upwards (occurs passively as you flex/abd GH joint)
• Accompanied by scapular elevation
Scapular Medial rotation
• Glenoid fossa turns downwards (occurs passively as you extend / adduct GH joint)
• Accompanied by scapular depression
List the muscles of the pectoral girdle responsible for scapular: Protraction Retraction Elevation Depression Lateral rotation Medial rotation
Protraction • Serratus anterior • Pectoralis minor Retraction • Rhomboid major • Rhomboid minor • Trapezius • Levator scapulae
Elevation
• Levator scapulae
• Upper fibers of trapezius
Depression • Pectoralis minor • Lower fibers of trapezius • Subclavius Lateral rotation • Trapezius • Serratus anterior
Medial rotation • Rhomboid major • Rhomboid minor • Pectoralis minor • Levator scapulae
ORIANS SERRATUS ANTERIOR
Serratus anterior
O:
• Via fleshy digitations to the outer surfaces of the upper 8/9 ribs and intercostal fascia
R:
Posterior
I:
• Costal surface of the medial border of the scapula
A:
• Protraction and lateral rotation of the scapula
FA
• Movements which drive the scapula forwards (pushing, punching)
• Major stabilizer of scapula during upper limb movements, holding medial border against the thoracic wall.
NS
• Long thoracic nerve (C5-C7)
ORIANS PECTORALIS MINOR
Pectoralis Minor
• Thin, flat triangular muscle, deep to pectoralis major
O:
• Outer borders of costal cartilage of ribs 3-5 and intercostal fascia
R:
• Superolateral
I:
• Supero-medial border of coracoids process via a short, flat tendon
A:
• Medial rotation and depression of scapula
• Accessory muscle of inspiration
FA
• Pulls scapula downwards and forwards during pushing and punching movements
NS:
• Medial pectoral nerve (C8-T1)
ORIANS SUBCLAVIUS
Subclavius
• Small, triangular muscle, lying between the clavicle and the first rib.
O:
• Short, thick tendon from the first rib and it’s cartilage, anterior to costoclavicular ligament
R:
• Obliquely superior and lateral.
I:
• Subclavian groove of inferior clavicle.
A:
• Depression of the clavicle
FA:
• Keeps clavicle stabilized during scapular movements
NS:
• Nerve to subclavius (C4-C6)
ORIANS TRAPEZIUS
Trapezius
• Large, flat triangular sheet of muscle
• Three parts – upper, middle, and lower
O:
Common origin for all three parts.
• Ligamentum nuchae
• Spinous processes of C7-T12 and intervening spinous ligaments
• Base of medial 1/3 of the superior nuchal line and the occipital bone.
Upper trapezius O: • Common origin R: • Infero-laterally I: • Posterior border of the lateral 1/3 of the clavicle A: • Elevation, retraction, and lateral rotation of the scapula. NS: Motor: • Spinal part of cranial nerve XI (accessory) Sensory: • Ventral rami C3-C4 Middle Trapezius O: • Common origin
R: Almost horizontally I: • Medial border of the acromion • Superior aspect of crest of scapular spine. A: • Retraction of the scapula NS: Motor: Spinal part of the cranial nerve XI (accessory nerve) Sensory : Ventral rami C3/C4
Lower Trapezius O: • Common origin R: • Superior and lateral
I:
• Converge to form a tendon that attaches to infero-medial aspect of the scapular spine.
A:
• Depression, retraction, and lateral rotation of the scapula
NS:
Motor: Spinal part of cranial nerve XI (accessory nerve)
Sensory: Ventral rami C3/C4
ORIANS OF RHOMBOID MAJOR?
Rhomboid Major
• Larger muscle than rhomboid minor but may be continuous with it
• Lies deep to trapezius
O:
• Spinous processes of T2 to T5 and the intervening supraspinous ligaments
R:
• Obliquely infero-laterally
I:
• Medial border of scapula between the spine of scapula and the inferior angle
A:
• Scapular retraction and medial rotation
FA
• Scapula stabiliser when other muscles are active
NS:
• Dorsal scapular nerve (C5)
ORIANS RHOMBOID MINOR?
Rhomboid Minor • Small, rectangular muscle. • Deep to trapezius and inferior to levator scapulae. • Lies on posterior thoracic cage O: From spinous processes of C7-T1 and supraspinous ligaments between them R: • Obliquely downwards and laterally I: • Medial border of the scapula at the level of the root of the spine of scapula (smooth triangular area) A: • Scapular retraction and medial rotation FA: • Scapula stabilizer NS: • Dorsal scapular nerve (C5)
ORIANS LEVATOR SCAPULAE
Levator Scapulae
• Strap-like muscle, lies superficial to the extensor muscles of the neck
• Upper fibers are inferior to sternocleidomastoid and the lower fibers deep to trapezius.
O:
Transverse processes from C1-C4
R:
Infero-laterally
I:
Medial border of the scapula - between the superior angle and base of the scapular spine
A:
Scapular elevation, retraction, and medial rotation.
FA:
Scapular stabilizer
NS:
Dorsal scapular nerve (C5)
How do the trapezius and serratus anterior function in lateral rotation of the scapula?
Both muscles bring the inferior angle of the scapula away from the midline and move laterally around the thoracic wall, increasing the available ROM of the shoulder for flexion and abduction
How do the rhomboids, levator scapula, and pectoralis minor function in medial rotation of the scapula?
These muscles:
• Medially rotate scapula against resistance
• Rhomboid major/minor and levator scapula pull medial side up, pectoralis minor pulls lateral side down.
How do you palpate the brachial pulse? (2)
- Palpate pulse on the medial side of the upper arm
- In the cleft between biceps brachii and triceps brachii muscles
OR
Find the cubital fossa on the anterior arm
Palpate medial to the biceps tendon, and lateral to the median nerve.
For each GH movement, identify the associated scapular movements: Flexion Extension Abduction Adduction Horizontal flexion Horizontal extension Lateral rotation Medial rotation
Flexion:
Lateral rotation, elevation
Extension:
Medial rotation, depression, retraction (to neutral)
Abduction
Lateral rotation, elevation, protraction
Adduction:
Medial rotation, depression, retraction (to neutral)
Horizontal flexion:
Protraction
Horizontal extension:
Retraction
Lateral rotation:
Slight retraction
Medial rotation:
Slight protraction
What is winging of the scapula caused by?
Paralysis of the serratus anterior muscle (severed long thoracic nerve) relaxes it’s attachment to the medial border of the scapula, allowing it to lift off the posterior thoracic cage.
At the GH joint, list the muscles responsible for:
Flexion Extension Abduction Adduction Medial rotation Lateral rotation
Shoulder Flexors • Deltoid (anterior) • Coracobrachialis • Pectoralis major (clavicular head) • Biceps brachii (long head)
Shoulder Extensors • Latissimus dorsi • Deltoid (posterior) • Pectoralis major (sternal head) • Teres major • Triceps (long head)
Shoulder abductors
• Supraspinatus
• Deltoid (middle)
Shoulder Adductors • Pectoralis Major • Teres major • Teres minor • Latissimus dorsi • Subscapularis • Coracobrachialis
Shoulder medial rotators • Subscapularis • Pectoralis major • Latissimus dorsi • Teres major • Deltoid (anterior)
Shoulder lateral rotators
• Infraspinatus
• Teres minor
• Deltoid (posterior)
ORIANS of the DELTOID MUSCLES
Deltoid (anterior, middle, posterior)
• Coarse, thick triangular multipennate muscle
Common Insertion:
• Deltoid tuberosity on the lateral humerus via a short, thick tendon.
Function:
• Resists downward displacement of humerus
Anterior Deltoid
O: • Anterior and lateral 1/3 of clavicle R; Obliquely inferior and posteriorly I • Common Insertion A • Strong flexor and medial rotator of the GHJ. NS • Axillary nerve (C5,C6)
Middle Deltoid O: • Lateral aspect of the acromion process via 4 tendinous slips R • Inferior I: • Common Insertion A: • Abduction of GHJ in the line of the scapula beyond the initial 20°. NS: • Axillary nerve (C5-C6)
Posterior Deltoid O: • Lower lip of the scapular spine. R Obliquely inferior and anterior I: • Common Insertion A: • Strong extensor and lateral rotator of the GHJ. • Acts as antagonist to pectoralis major and latissimus dorsi during adduction of the arm to counter-act medial rotation. NS • Axillary nerve (C5,C6)
