What type of joint is the sternoclavicular joint?
Atypical synovial joint
What anatomy is involved in the sternoclavicular joint?
Medial clavicle
Manubrium
1st costal cartilage
What makes the sternoclavicular joint atypical?
Saddle shaped, two separate cavities - separated by fibrocartilaginous disc
Atypical because the bone ends are covered by fibrous cartilage rather than hyaline cartilage
Movement occurs in the A-P, vertical planes with some rotation (grinding sliding rotation, protect articular cartilage)
- rotation is passive, 40 degrees with full abduction
List the 4 ligaments surrounding the Sternoclavicular joint capsule the reinforce the stability
Interclavicular Costoclavicular *****fulcrum, see-saws around this point, very important for stability Anterior sternoclavicular Posterior sternoclavicular - anterior weaker than posterior - anterior dislocation more common
Acromioclavicular joint
- what is the type of joint?
- what anatomy is involved?
- what movements occur
Small synovial joint
Lateral end clavicle and the acromion
Articular surfaces are covered by fibrocartilage with a fibrocartilage disc in the joint
Moves with the scapula
Movements are passive
The acromion slides to and fro, the centre of rotation being through the conoid ligament
What ligaments reinforce the acromioclavicular joint capsule
Acromioclavicular ligament - superior to the joint
Coracoclavicular ligament - important accessory ligament
Trapezoid ligament - transmits forces from the glenoid to the clavicle
Conoid ligament - Centre of rotation
Clavicle fracture between costoclavicular ligament and trapezoid ligament
Trapezius Origin
Superior nuchal line
External occipital protuberance
Ligamentum nuchae
Spinous processes CVII to TXII and related ligaments
Trapezius insertion
U shaped insertion
- lateral third clavicle
- acromion
- spine of the scapula
Trapezius innervation
CNXI (spinal part) and proprioception from C3-4 anterior rami
- not myotomes of the upper limb
Trapezius action
Action is rotate the glenoid fossa upward
Deltoid muscle
- Shape
- Origin
- Insertion
- Large and triangular
- Origin mirrors the insertion of the trapezius
- lateral third clavicle
- acromion
- spine of scapula - Deltoid tuberosity of humerus
Deltoid muscle
- Innervation
- Major function
- Other functions
- Axillary nerve (C5,6) 5cm below the acromion
- Abduction - of the arm beyond 15 degrees (supraspinatus does first 15)
- Anterior longitudinal fibres assist PM with shoulder flexion
Posterior longitudinal fibres assist LD with extension
Intermediate fibres are multipennate and very strong (4 septa from above, 3 septa from below)
Levator scapula
- Origin
- Insertion
- Innervation
- Movement
- Transverse processes of C1-4
- Medial border scapula from the superior angle to the root of the spine
- Dorsal scapula nerve (C5) and directly from the anterior rami of (C3-4)
- Draws scapula up and medial
Rhomboid minor
- Origin
- Insertion
- Innervation
- Retract medial border
- From the lower end of ligamentum nuche and the spines CVII & T1
- Inserts into the smooth triangular area at the root of the Spine of the scapula below the levator scapula
- Dorsal scapula nerve (C5)
Rhomboid Major
- Origin
- Insertion
- Innervation
- Movement
- From the spines of TII - V and the intervening supraspinous ligament
- Inserts along medial border of the scapula down the inferior angle
- Dorsal scapula nerve (C5)
- Both retract the medial border
Supraspinatus
Origin
Pathway
Insertion
From the medial two thirds of the supraspinous fossa
Passes under the acromion
Inserts into greater tuberosity of the humerus
Laterally also blends with the capsule
Supraspinatus
Innervation
Movement
Suprascapular nerve (C5,6) Initiates abduction
Infraspinatus
- Origin
- Pathway
- Insertion
From the medial two thirds of the infraspinous fossa
Passes posterior to the glenohumeral joint
Inserts on the middle facet of the greater tuberosity
Infraspinatus
- Innervation
- Movement
Suprascapular nerve (C5,6) Lateral rotation of the shoulder
Teres Minor Origin Uniqueness of muscle Insertion Innervation Movement
From flattened area below the infraglenoid tubercle
Cord like muscle
Insertion greater tubercle of the humerus
Part of rotator cuff
Axillary nerve (C5,6)
Lateral rotation
Teres major Origin Insertion Innervation Movement Unique anatomy
From a large oval area on the lateral border of the scapula
Broad flat tendon attaches to the medial lip of the bicipital groove
Inferior scapular nerve (C6-7)
Medial rotation
The long head of the biceps passes vertically down between teres minor and major (forming various spaces)
Suprascapular notch
- formed into foramen by what
- what structures pass in and around
Transformed into suprascapular foramen by the superior transverse scapular ligament
- if this ligament thickened could cause impingement of suprascapular nerve (therefore unable to abduct first 15 degrees)
Suprascapular nerve passes through the foramen and the artery & vein pass over the ligament then passes around the root of the spine of the scapula
Uniqueness of suprascapular nerve
Only one to come off the upper trunk of the cervical plexus
The quadrangular (quadrilateral) space
- things that go through
- borders
Transmits the axillary nerve and posterior circumflex humeral artery
Borders:
Upper according to last’s it is subscapularis (but also could be teres minor)
Lateral - humerus
Lower - teres major
Medial - long head of triceps
