Shoulder and Elbow Joint Flashcards
what type of joint is shoulder
multi-axial, ball-and-socket, synovial joint.
formed by the articulation of the head of the humerus with the glenoid fossa of the scapula
what movements can the shoulder joint do?
It permits the arm to be extended or flexed in the sagittal plane
abducted through 180 degrees (above the head) or adducted behind the thorax,
rotated about its long axis
circumducted (combination of all other movements)
The Shoulder joint is made from the end of the humerus and the scapula.
Describe the humerus
The articular surface of the head forms 2/5ths of a
sphere and is covered with hyaline cartilage.
It is considerably larger than the glenoid fossa with which it articulates - hence the great mobility of the shoulder joint.
Note also the very short anatomical neck, which separates the head from the greater and lesser tubercles, which are in turn separated by the intertubercular groove (spanned by the transverse humeral ligament and holds the long head of biceps brachii).
The surgical neck of the humerus is the upper end of the shaft of the bone, below the tubercles, and is a common site of fracture.
The Shoulder joint is made from the end of the humerus and the scapula.
Describe the Scapula
The very shallow, pear shaped glenoid fossa of the scapula faces, in the anatomical position, antero-laterally and is smaller in area than the articular surface of the head of the humerus.
It does not in any sense ‘hold’ the head of the humerus in position. The fibrocartilaginous glenoid labrum surrounds the fossa but does little to improve stability of the joint.
Articular capsule
Describe its location
The fibrous capsule of the shoulder joint extends from the bone of the scapula around the margins of the labrum to the anatomical neck of the humerus, except inferiorly where it is attached to the surgical neck 1 cm below the articular margin; i.e. the capsule is lax under the joint to accommodate abduction of the arm.
Describe the articular capsule
- the opening
upper end
There is an opening in the capsule anteriorly through which the synovial cavity of the joint is in communication with the subscapularis bursa. At the upper end of the intertubercular groove the capsule is thickened to form the transverse ligament, which holds down the tendon of the long head of biceps
Identify the regions of the humerus and scapula
Lecture slide
What is the synvoial capsule, where is it, function
The synovial capsule is attached around the labrum, lines the fibrous capsule, and is reflected back to attach to the anatomical head of the humerus at the articular margin.
It communicates with the subscapular bursa, forms a sleeve for the tendon of the long head of biceps (which is said to be intracapsular, but extrasynovial), and pouches out from under the lateral margain of the fibrous capsule in the region of the transverse ligament
Draw the coronal section of shoulder joint
Lecture slide
What are the issues with the capsule?
it can’t support the joint in all positions in
anatomical position capsule across the top is relatively tight so supports the joint but the capsule down below has to be loose so it doesn’t reduce joint movement , this means that if arm is in position anywhere between 2 extreme ranges of motion. Capsule is not supporting it at all
articular capsule is not really a supportive feature of highly mobile joints , instead use muscle to stabilise it - active stabilisation
How many ligaments of the shoulder joint and what are they
4
Extracapsular (outside the shoulder joint capsule)
- Coracoacromial ligament
Capsular (part of the shoulder joint capsule)
- Coracohumeral ligament
- Transverse humeral ligament
- Glenohumeral ligaments
Describe the extracapsular ligament
- anatomy location
- function
- The Coracoacromial ligament spans the gap between the coracoid process and the acromion, thereby forming a superior arch (coracoacromial arch) to the shoulder joint.
This arch is important for preventing superior dislocation of the glenohumeral joint.
Capsular: Coracohumeral ligament
Describe its structure and movements and location
A strong flattened band capable of suspending the arm, but is lax in abduction; it reinforces the capsule superiorly.
Located at base of coracoid to greater tubercle
Capsular: Transverse humeral ligament
Location, structure
spans between the greater and lesser tubercle, holding the tendon of the long head of biceps brachii in position as it emerges from the capsule.
Capsular: Glenohumeral ligament
- Located
-Function
are three
weak thickenings on the interior and
anterior aspects of the capsule.
Support inferior and anterior aspects of the joint
Label the ligaments on the diagram
Lecture slide
Intracapsular structures: Tendon
location, sheathed or unsheated?
Why does it pass thorugh where it does
The tendon of the long head of biceps originates from the supraglenoid tubercle of the scapula and runs “through” the joint into the intertubercular groove, where it is held down by the transverse humeral ligament.
The tendon is sheathed in a sleeve of synovium, which pouches out from under the transverse humeral ligament.
By passing through the joint and the groove, the tendon of the long head of biceps provides some stability to the head of the humerus, but more importantly is thereby provided with a line of pull in parallel with the long axis of the humerus in order to better flex the elbow
Intracapsular structures:
Bursae
- Purpose
minimise friction of tendons as they pass across bones or other tendons to their insertions.
Bursae types and location
(1) The subscapular bursa found under the coracoid process (sometimes this part is labelled the subcoracoid bursa) and covering the neck of the scapula is in continuity with the synovial cavity of the shoulder joint. This bursa protects the subscapularis tendon from the underlying ridge of the glenoid fossa during contraction.
(2) The subacromial bursa separates the overlying corcoacromial arch from the supraspinatus and infraspinatus tendons as they pass to their insertions on the facets of the greater tubercle of the humerus.
(3) the subdeltoid bursa is a lateral continuation of the subacromial bursa found under the deltoid muscle.
Intracapsular structures:
Muscles: Rotator Cuff
- what mscles form the cuff
They form the rotator cuff and are the major supply of stability to the joint: Supraspinatus, infraspinatus, teres minor and subscapularis.
What is the main movement for each of the muscles in the rotator cuff
Supraspinatus and deltoid (multipennate central fibres) are the chief abductors
teres muscles preventing upward displacement of the head of the humerus
infraspinatus the chief lateral rotator
subscapularis, pectoralis major and teres major the chief internal rotators
and adductors
clavicular fibres of pectoralis major and anterior fibres of deltoid flex the arm on the shoulder
posterior fibres of deltoid and latissimus dorsi extend the arm at the shoulder
Subscapularis
- origin
- insertion
-movement
Origin: Subscapular
fossa
Insertion: Lesser
tubercle
1 degree: Internally rotates arm
Supraspinatus
- origin
- insertion
-movement
“O” = supraspinous fossa
Insertion: Superior facet
Abducts arm
Infraspinatus
- origin
- insertion
-movement
o= Infraspinatus fossa
i = middle facet
Externally rotates arm
Teres minor
- origin
- insertion
-movement
o= lateral border of scapula
i= inferior facet
Externally rotates arm
The elbow joint
What are the 3 joints and what is the degree of flexion/extension
humero-ulnar, humero-radial, and radio-ulnar
The humero-ulnar and humero-radial joints together comprise a pure hinge joint with 135 degree of flexion/extension.
What movements does
superior radio-ulnar (R/U) joint provide in elbow joint
The superior radio-ulnar (R/U) joint provides for pronation and supination of the forearm
Label the joints in the elbow and other featuers of the elbow joint
humero-ulnar: Trochlea, olecranon, coronoid process
humero-radial: Capitulum, superior surface of radius, head
and radio-ulnar: Radial notch, Head of radius
Ligaments of the elbow (3) and describe them
The triangular ulnar or medial collateral ligament
- apex attached to the medial epicondyle of the humerus and its base fans out to attach to the upper, medial aspect of the ulna
- divided into three smaller (anterior, intermediate and posterior), connecting ligaments.
The radial or lateral collateral ligament
- extends from the lateral epicondyle to;the annular ligament
the annular ligament
attached to the edges of the radial notch of the ulna and surrounds the head of the radius.
