Shoulder joint: Bones and ligaments

Clavicle: anterior border

In the lateral third, the anterior border is concave, thin, and rough. Approaching the medial end, the surface becomes smoother. It provides attachment for deltoid. The medial two-thirds provide the clavicular attachment of pectoralis major and are roughened.

Inferior glenohumeral ligament (general) 1) Origin 2) Insertion 3) Function

1) Glenoid margin, below the spinoglenoid notch in its anterior border to the adjacent anterior border (3 o'clock to 9 o'clock position) 2) The anteroinferior part of the anatomical neck 3) This ligament forms the thickest part of the joint capsule and is the largest and most important of the glenohumeral ligaments. - This ligament functions hammock, cradling the humeral head as abduction increases.

Inferior glenohumeral ligament - This ligament is made of three components. State what they are

1) The anterior band 2) The axillary pouch 3) The posterior band

Middle glenohumeral ligament 1) Origin 2) Insertion 3) Function

1) The glenoid labrum, inferior to the SGHL 2) The anterior aspect of the anatomic neck of the humerus, medial to the lesser tuberosity 3) Inferior translation of the abducted and externally rotated shoulder is limited as a secondary restraint function of the MGL.

Coracohumeral ligament 1) Origin 2) Insertion

1) The lateral aspect of the coracoid. 2) The greater tuberosity.

Superior glenohumeral ligament (SGHL) 1) Origin 2) Insertion 3) Fucntion

1) The upper pole of the glenoid fossa and the base of the coracoid process, the MGHL, the biceps tendon and the labrum. 2) The lateral lip of the lesser tuberosity 3) This ligament represents the primary capsuloligamentous restraint to inferior translation of the unloaded, abducted shoulder joint.

Inferior glenohumeral ligament - What structure does the posterior band contribute to?

- This structure contributes to the formation of the posterior labrum.

Inferior glenohumeral ligament - What structure does the anterior band contribute to?

- This structure forms the anterior labrum at its medial attachment to the glenoid. - This relationship between this structure and the anterior labrum is sometimes called the inferior glenohumeral ligament labral complex (IGLLC)

Inferior glenohumeral ligament - What are the attachments of the axillary pouch?

- This structure is located between the anterior and posterior bands. - This structure also attaches to the inferior 2/3 of the circumference of the glenoid labrum.

Bony landmarks of the scapula - Describe the structure of the Spine of the scapula

- This structure passes horizontally from the upper dorsal surface of the body of scapula. - Its lateral border is rounded and forms part of the spinoglenoid notch. - The posterior border is thickened to form the crest, which lies subcutaneously. The crest gives attachment to trapezius superiorly and deltoid inferiorly. - The medial end reaches the medial border of the scapula at the junction of upper and middle thirds. - The acromion arises from the lateral aspect of the spine.

Humeral head motion to pull the ligament taut IGL

Inferior translation In adduction, the IGL is lax. It tightens with increasing abduction, and the anterior and posterior bands move superiorly with respect to the humeral head. At 90° of abduction, the IGL is the primary restraint for anterior and posterior dislocations.

Biomechanics: - What movement does the middle glenohumeral joint limit

Lateral rotation

What is the function of the scapula ****

Primarily for muscle attachment and to act as stable base for upper limb activities Muscles maintain correct alignment of glenoid for the humeral head Optimum scapular function is achieved by muscles moving/controlling it and by movements at the AC and SC joints

What other ligament is the SGHL closely related to?

The coracohumeral ligament.

Bony landmarks of the scapula: - Describe the structure of the superior border of scapula

This bony process passes laterally and downwards and it is notched medial to coracoid process. - The coracoid process arises from near its lateral end.

Bony landmarks of the scapula - Describe the structure of the supraglenoid tubercle

This is a small roughened area that is found immediately above the glenoid cavity. - It encroaches on the base of the coracoid process.

What bones are involved in the shoulder joint?

1. Scapula 2. Humerus 3. Clavicle

Bony landmarks of the scapula - What structures attach to the acromion process?

1. The clavicle articulates with the acromion at the oval facet on its anterior surface. 2. This structure gives attachment to the deltoid laterally and anteriorly 3. Fibers from the trapezius attach to the medial margin.

The coracoacromial arch 1. What is it formed of? 2. What is it's role?

1. The coracoid process, the acromion, clavicle and acromioclavicular joint, and the coracoacromial ligament. 2. It stabilizes the humeral head and prevents superior ascent

What are the four joints that make up the shoulder joint?

1. The glenohumeral joint (This is what the shoulder joint is commonly referred to as) 2. The acromioclavicular (AC) joint 3. The sternoclavicular (SC) joint 4. The scapulothoracic joint

Bony landmarks of the scapula - What structures attach to the infraglenoid fossa?

1. The infraspinatus muscle arises from this structure, with the exception of the lateral border and the region around the neck 2. The margins of this structure gives attachment to the infraspinatus fascia

Bony landmarks of the scapula - What structures attach to the supraglenoid fossa?

1. The supraspinatus muscle arises from the medial two thirds of this fossa. 2. The margins of this structure gives attachment to the supraspinatus fascia

Biomechanics: - What movement does the inferior glenohumeral joint limit

90 degrees of abduction and lateral rotation (anterior band) and medial rotation (posterior band)

Ligaments of the glenohumeral joint: - Acromioclavicular ligament 1) origin 2) insertion

A quadrilateral band covering the upper part of the acromioclavicular joint: 1. The upper lateral end of the clavicle. 2. The upper surface of the acromion.

Deltoid tuberosity

About half way down the body of humerus there is a prominent roughened area laterally, the deltoid tuberosity, to which is attached the deltoid muscle. The radial groove runs behind and below the tuberosity

Biomechanics: - What movement does the superior glenohumeral joint limit

Adduction

Stabilisers of the glenohumeral joint - Dynamic

All muscles passing between SG and humerus Inferiorly - long head of triceps Superiorly - long head of biceps Rotator cuff muscles Supraspinatus, infraspinatus, subscapularis and teres minor

Humeral head motion to pull the ligament taut SGL

Anterior and inferior translation of the humeral head

Humeral head motion to pull the ligament taut MGL

Anterior translation of the humeral head during 45-60 of abduction

Axillary Nerve ***

Arises from the terminal branch of the post cord C5, C6. Passes along the inferior-lateral border of subscapularis and the inferior border of the capsule. Where it moves posteriorly. It follows through to the posterior-lateral surface of the humerus. Supplies teres minor and deltoid and the skin overlying the inferior half of deltoid.

Acromial end

Concave anteriorly and flattened from above downwards, the lateral end of the clavicle articulates with the medial aspect of the acromion. It bears an oval articular facet, facing slightly downwards and laterally.

Capitulum

Distally the humerus articulates with the radius at the capitulum and the ulna at the trochlea.

Trochlea

Distally the humerus articulates with the radius at the capitulum and the ulna at the trochlea.

Coroniod fossa

Distally the humerus articulates with the radius at the capitulum and the ulna at the trochlea. The anterior aspect of the distal end possesses coronoid and radial fossae and the posterior aspect a large olecranon fossa. Prominent medial and lateral epicondyles are readily palpable.

Radial fossa

Distally the humerus articulates with the radius at the capitulum and the ulna at the trochlea. The anterior aspect of the distal end possesses coronoid and radial fossae and the posterior aspect a large olecranon fossa. Prominent medial and lateral epicondyles are readily palpable.

Medial epicondyle

Distally, the humerus articulates with the radius at the capitulum and ulna at the trochlea. The anterior aspect of the distal end possesses coronoid and radial fossae and the posterior aspect a large olecranon fossa. Prominent medial and lateral epicondyles are readily palpable.

Stabilisers of the glenohumeral joint - Static

Glenoid Capsule (-ve intra articular pressure) Glenohumeral ligaments (to an extent) Coracoacromial arch

Pathologies associated to the inferior glenohumeral joint

Pathology Anterior Glenohumeral Instability The most common of all glenohumeral joint instabilities is anterior instability, particularly that produced by lesions of the IGL labral complex at its insertion onto the labrum and the scapula neck. The anterior band of the IGLC, which forms the anterior labrum, has been shown by Turkel to be the primary restraint to anterior translation of the humeral head at 90° of abduction. It is best demonstrated on sagittal oblique MR images and is routinely seen on MR arthrography in this plane (Slides 1, 2, 3, 4, 5, 6, 7). Bankart lesion Avulsion of the glenohumeral ligament labral complex from the glenoid rim, known as a Bankart lesion, involves detachment of the anterior labrum and the IGLC from the anterior glenoid rim. A Bankart lesion can involve labral avulsion without a bony inferior glenoid rim fracture (Slide 1, Slide 2). MR demonstrates either the anterior labral avulsion or labral and anterior inferior glenoid rim fracture. The relationship of the anterior band of the IGL to the avulsed labrum is identified at the level of the glenoid fossa on sagittal oblique MR images. Open and some arthroscopic stabilization procedures involve capsular plication combined with reattachment of the IGLLC (arthroscopic Bankart repair). The abduction external rotation position of the arm (ABER view, Slide 1, Slide 2) may be used to increase the conspicuity of anterior inferior labral tears and articular surface lesions of the rotator cuff. The ALPSA lesion The anterior labroligamentous periosteal sleeve avulsion (ALPSA) lesion represents avulsion of the IGL through its anterior band attachment to the anterior labrum. Although similar to the Bankart lesion, in the ALPSA lesion the anterior scapular periosteum is intact, allowing the labroligamentous structures to displace medially and rotate inferiorly on the scapular neck. In the Bankart lesion, the anterior scapular periosteum ruptures, resulting in displacement of the labrum and attached ligaments anterior to the glenoid rim. On axial MR images of the ALPSA lesion the anterior labrum with stripped periosteum can be seen to be displaced medially and rotated inferiorly on the neck of the glenoid. The HAGL lesion In the humeral avulsion of the glenohumeral ligament (HAGL) lesion, the IGL complex tears at its mid-portion or is avulsed from its humeral insertion (Slide 1, Slide 2). The HAGL lesion can be demonstrated arthroscopically, and in some cases is solely responsible for anterior shoulder instability. However, it occurs significantly less frequently than the classic Bankart lesion. The HAGL lesion may exist in patients with anterior instability with or without an associated anterior labral tear. The HAGL lesion is treated with surgical reattachment of the glenohumeral ligament to its humeral insertion. Identification of the humeral detachment of the inferior glenohumeral ligament on MR images usually requires the presence of a joint effusion or the use of MR arthrography. When depicted, the axillary pouch is converted from a fluid-distended U-shaped structure to a J-shaped structure as the inferior glenohumeral ligament drops inferiorly. The direct extension of fluid or contrast can be identified between the humerus and the avulsed inferior glenohumeral ligament. Posterior Superior Glenoid Impingement Posterior superior glenoid impingement is a recently recognized mechanism of injury producing repetitive impingement of the inferior surface of the rotator cuff in the athlete who uses a throwing motion. Five structures are at risk from this mechanism of injury: the superior labrum, the rotator cuff tendon, the greater tuberosity, the inferior glenohumeral ligament or labrum, and the superior bony glenoid. Jobe found that damage to more than one of these structures resulted in posterior superior glenoid impingement. This mechanism of injury represents superior or posterior-superior angulation in the position of abduction and external rotation (the position of throwing). MR arthrography, performed with the arm positioned in abduction and external rotation, is the modality of choice for demonstration of associated cuff and labral pathology. Multidirectional Glenohumeral Instability As a characteristic of multidirectional instability of the glenohumeral joint, force applied distally in the upper extremity with the patient's arm abducted causes inferior subluxation of the humeral head. This produces a visible sulcus (the sulcus sign) between the prominence of the acromion and the inferior subluxed humeral head. This can also be observed in patients without symptoms with laxity signs often in more than one direction. In classic multidirectional instability, the ligament laxity is bilateral and atraumatic. No visible ligament labral lesions are seen in patients with true multidirectional instability of the glenohumeral joint. The capsular ligaments are redundant, and the labrum is often hypoplastic. Some patients with multidirectional laxity, however, present with unidirectional pathology and experience dislocation predominantly in only one direction.

Biomechanics - Rotator cuff

RC muscles act as 'protectors' - keep humeral head centred on glenoid fossa Dynamic stabilisers - especially in mid range where capsule and ligaments are lax Reduce upward shearing forces during movements of the humerus Steer the head of humerus during upper limb movements Act as a fulcrum on which deltoid can work Short fibre length - attached close to axis of rotation can produce relatively large amounts of force in a short range - compress head of humerus into glenoid Have good endurance

deltoid tubercle of clavicle

Situated on the lateral third of the anterior border of the clavicle is a small deltoid tubercle; it provides attachment for deltoid.

The coracoclavicular ligament - What two ligaments make up this structure?

The coracoclavicular ligament joins the coracoid process to the inferior surface of the lateral end of the clavicle. There may be fat or a bursa between the two. 1. Trapeziod ligament 2. Conoid Ligament

.Synovial membrane of the glenohumeral joint

Synovial membrane of the Shoulder Joint The synovial membrane of the shoulder joint attaches to the articular margins of the scapular and the humerus. It extends through the anterior opening of the capsule as the subscapularis bursa that may separate to form the subcoracoid bursa. It occasionally, extends through the posterior opening of the capsule as the infraspinatus bursa. The long head of biceps travels through the capsule and is surrounded by a tubular sheath of synovial membrane, so is extra-synovial. This sheath travels under the transverse humeral ligament to extend 2cm into the arm.

Clavicle facet for first rib

The articular facet for the first rib is a small, semi-oval area on the inferior surface of the clavicle. It is a continuation of the inferior part of the articular facet for the sternum onto the inferior surface of the clavicle. The facet articulates with the cartilage of the first rib, rather than the bone. The margins of the articular facet are rough due to the attachment of the ligaments holding the sternoclavicular joint together.

clavicle sternal facet

The articular facet for the sternum is on the medial end of the clavicle. It is directed medially, inferiorly, and somewhat anteriorly. It is concave anteroposteriorly and convex superoinferiorly, making it a saddle-shaped joint. It does not articulate directly with the bone of the sternum but with the articular disc, which lies within the joint capsule. The disc is attached to the superoposterior border of the clavicular articular surface. The margins of the articular facet are rough due to the attachment of the ligaments holding the sternoclavicular joint together.

Pathology associated to the coracoacromial ligament

The coracoacromial ligament is the key structure of the coracoacromial arch, and plays an important role in the spectrum of impingement disorders of the shoulder. Anterior acromial spurs, caused by chronic irritation of the humerus against this ligamentous structure, can form within the acromial portion of the coracoacromial ligament. Anterior acromial spurs are frequently identified adjacent to the acromial attachment of the coracoacromial ligament. On coronal oblique MR images the normal low signal intensity acromial attachment of the coracoacromial ligament may be mistaken for an anterior acromial spur. This pseudospur is produced by the additive thickness of the coracoacromial ligament and the inferior acromial cortex. In acromioplasty performed for chronic impingement, the coracoacromial ligament and the anterior inferior margin of the acromion are resected. The Coracoacromial Ligament in Impingement The trapezoid-shaped coracoacromial ligament attaches to the undersurface of the acromion in a broad or wide insertion. Arthroscopically, the coracoacromial ligament may present in a plane almost perpendicular to the anterior aspect of the supraspinatus tendon as viewed from above. The variable size and thickness of the coracoacromial ligament may explain the MR observation of ligament hypertrophy and, especially when the wide portion of the ligament inferior to the acromion is affected, may contribute to narrowing of the supraspinatus outlet. Arthroscopic findings in impingement include erosive changes in the acromial attachment of the coracoacromial ligament. Various enthesopathic bone changes can produce different configurations of the hooks and spurs on the inferior surface of the acromion.

Clavicle: articular facet for acromion

The facet is the clavicular articular surface of the acromioclavicular joint. Located at the lateral end of the clavicle, it articulates with the medial margin of the acromion. It is a narrow, oval-shaped with the long axis lying anteroposteriorly and the face directed inferomedially. The two surfaces are flat, but either may be convex, with the other correspondingly concave.

What foramen is located between the SGHL and the IGHL?

The foramen of Rouviere is located between these two ligaments

What foramen is located between the SGHL and the MGHL?

The foramen of Weitbrecht is located between these two ligaments

Greater tubercle of humerus

The greater tubercle is a bony prominence on the lateral side of the upper end of the humerus. It merges with the body below, separated from the head by the anatomical neck. It has three facets, superior for supraspinatus, middle for infraspinatus and posterior for teres minor. A crest extends from the anterior aspect of the tubercle onto the upper shaft, forming one wall of the intertubercular groove. The groove separates it for the lesser tubercle. The greater tubercle projects beyond the lateral border of the acromion, covered by deltoid. It forms the rounded contour of the shoulder.

Anatomical neck of humerus

The head is limited by the anatomical neck, a slightly narrowed area encircling the bone at the edge of the articular cartilage. This separates the head from the tubercles.

Bony landmarks of humerus: - Head of the humerus

The head, greater and lesser tubercles form the upper end of the humerus, merging with the body at the surgical neck. The head forms one third of a sphere, and faces posteromedially to articulate with the glenoid fossa of the scapula. It is covered with hyaline cartilage, thicker centrally and thinner towards the periphery. The reverse is true for the glenoid fossa, where cartilage is thinner centrally and thicker towards the glenoid rim.

The bicipital groove /intertubercular groove/ sulcus intertubercular

The intertubercular or bicipital groove is located between the greater and lesser tuberosities along the anterior surface of the humerus. The tendon of long head of biceps, with its synovial sheath, lies in the groove, held in place by the transverse humeral ligament. Pectoralis major crosses in front of the groove to insert on the crest of the greater tubercle. Teres major is inserted into the crest of the lesser tubercle. Latissimus dorsi curves round teres major to insert in the floor of the groove.

Conoid ligament 1) Origin 2) Insertion

The is the triangular ligament that is a part of the coracoclavicular ligament. 1) The posterior surface of the root of the coracoid process, medial to trapezoid ligament. 2) This ligament extends superomedially to its attachment to the conoid tubercle.

Lesser tubercle of humerus

The lesser tubercle is separated from the greater tubercle by the intertubercular groove, and from the head by the anatomical neck. The medial side of the tubercle has an impression for the tendon of subscapularis. The muscle insertion extends down onto the surgical neck. A crest extends from the anterior aspect of the tubercle onto the upper shaft, forming one wall of the intertubercular groove. The tubercle can be felt through deltoid just lateral to the tip of the coracoid process.

impression for costoclavicular ligament

The medial end is roughened inferiorly by the insertion of the costoclavicular ligament, which attaches the medial end of the clavicle to the first rib. There may be a "notch like" depression, referred to as the rhomboid fossa.

What are the functions of the SGHL and the coracohumeral ligament?

These two ligaments contribute to the stabilization of the GHJ and prevent posterior and inferior translation of the humeral head.

inferior surface of clavicle

The medial two-thirds of the shaft is convex anteriorly and approximately circular in cross-section; it has anterior, superior, posterior, and inferior surfaces. The lateral third of the shaft is concave anteriorly and flattened from above downwards; it has superior and inferior surfaces, and anterior and posterior borders. The inferior surface is grooved laterally for the attachment of the subclavius muscle. On its medial part is a roughened area for the insertion of the costoclavicular ligament.

anterior surface of clavicle

The medial two-thirds of the shaft is convex anteriorly and approximately circular in cross-section; it has anterior, superior, posterior, and inferior surfaces. The lateral third of the shaft is concave anteriorly and flattened from above downwards; it has superior and inferior surfaces, and anterior and posterior borders. The sternocleidomastoid muscle attaches medially to the superior surface of the clavicle shaft.

Olecranon fossa

The olecranon fossa is a deep triangular depression on the posterior side of the humerus, superior to the trochlea, in which the summit of the olecranon is received during extension of the forearm.

Bony landmarks of the scapula - There acromial angle is a landmark at the scapula. State what structures meet to form this

The posterior border of the spine and the lateral border of the acromion meet at the acromial angle.

conoid tubercle

The rounded conoid tubercle projects from the posterior edge of the clavicle at the junction of the medial three quarters and lateral quarter, at the end of the trapezoid line. It gives attachment of the conoid part of the coracoclavicular ligament.

Which bursa is found in between the acromion, coracoacromial ligament, and the rotator cuff?

The subacromial bursa

Superior transverse scapular ligament 1. Origin 2. Insertion

The superior transverse scapular ligament bridges the scapular notch, forming the scapular foramen. 1. The base of the coracoid process 2. The medial end of the scapular notch.

Lateral supracondylar ridge

The supracondylar part of the lateral border of the humerus becomes more prominent, forming the lateral supracondylar ridge, which curves downwards to end at the lateral epicondyle.

State the nerve that runs through the scapular foramen, along with the vessels that run over the superior scapular ligament.

The suprascapular nerve runs through this foramen. The transverse scapular vessels cross over the ligament.

Bony landmarks of the scapula - State where the supraspinous and infraspinous fossae are found in respect to the spine of the scapula

The supraspinous fossa lies above the spine, with the infraspinous fossa below.

Surgical neck of humerus

The surgical neck is the junction between the upper end and the body. The circumflex humeral vessels and the anterior branch of axillary nerve wind round the bone at this level. The surgical neck is a common site for fractures.

Transverse humeral ligament

The transverse humeral ligament unites greater and lesser tubercles, converting the intertubercular groove into a tunnel.

Spiral groove/ Radial groove

The upper half of the posterior body of the humerus is marked by a shallow groove for the radial nerve, running obliquely downwards and laterally to reach the lateral border below the deltoid tuberosity. The radial nerve and profunda brachii artery lie in the groove. The tendon of lateral head of triceps arises from the humerus above the groove.

subclavian groove

There is a shallow groove on the inferior aspect of the mid shaft of the clavicle for the subclavius muscle. Clavipectoral fascia encloses the muscle and is attached to the edges of the groove.

What does the MGHL, superior part of the IGHL and the subscapularis tendon all contribute to?

These structures all contribute to anterior stability at 45° of abduction.

clavicle sternal end

This is enlarged, its articular surface facing medially and slightly downwards. It articulates with a disc, which separates it from the clavicular notch of the manubrium and first costal cartilage. The upper aspect of this surface gives attachment to the disc, and the interclavicular ligaments. The articular capsule is attached to the margins of the articular surface. The notch on the manubrium is shallow, and the medial end of the clavicle projects above its upper border where it is easily palpable.

Trapezoid ligament 1) Origin 2) Insertion

This is the part broad, thin and quadrilateral ligament that is a part of the coracoclavicular ligament 1) upper apsect of the coracoid process 2) the trapezoid line on the inferior surface of the clavicle.

What is the Inferior glenohumeral ligament also known as?

This ligament is also known as the inferior glenohumeral ligament complex. - This is because it is comprised of three aspects

Ligaments of the glenohumeral joint: - Coracoacromial ligament 1) origin 2) insertion

This ligament, a triangular band of two fascicles, originates 1. The lateral aspect of the coracoid process 2. The anterior, medial, and inferior surfaces of the acromion.

Bony landmarks of the scapula - What structures attach to the subscapular fossa?

This structure gives attachment to subscapularis.

Bony landmarks of the scapula - What structures attach to the coracoid process?

This structure gives attachment to the following: 1. coracobrachialis 2. short head of biceps 3. pectoralis minor muscles 4. coracoclavicular ligaments.

Bony landmarks of the scapula - What structure attaches to the supraglenoid tubercle?

This structure gives attachment to the long head of biceps tendon.

Bony landmarks of the scapula - What structure attaches to the infraglenoid tubercle?

This structure gives attachment to the long head of triceps tendon.

Bony landmarks of the scapula - Describe the structure of the coracoid process

This structure is a finger like bony spur that projects upwards from the upper aspect of the head and neck of the scapula, and then bends sharply forwards and laterally. The tip is palpable below the outer end of the distal clavicle, through the anterior fibers of deltoid.

Bony landmarks of the scapula - Describe the structure of the Infraglenoid tubercle

This structure is a rough triangular area that is found below the glenoid cavity on the upper end of the lateral border scapula

Bony landmarks of the scapula - Describe the structure of the subscapular fossa

This structure is located on the costal surface of the scapula and it is gently concave and lightly ridged.

Bony landmarks of the scapula - Describe the structure of the supraglenoid fossa

This structure lies on the dorsal aspect of the scapula, above the spine.

Bony landmarks of the scapula - Describe the structure of the infraglenoid fossa

This structure lies on the dorsal aspect of the scapula, below the spine of the scapula

Bony landmarks of the scapula - Describe the structure of the lateral border of scapula -

This structure passes inferiorly and medially from glenoid to inferior angle. - Teres minor arises from the dorsal aspect of the upper two thirds.

Bony landmarks of the scapula - Describe the structure of the acromion process

This structure projects anteriorly from the lateral end of the spine and it slopes partially upwards - There is also a small oval facet on the anterior aspect of the medial border. surface.