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Anatomy of Shoulder and Arm Bony Anatomy Dr. Fadel Naim Orthopedic Surgeon Faculty of Medicine IUG-Gaza 777777777777777777777777 ِ اَل ُأ ْق ِس ُم ِب اي ْو ِم الْ ِق ايا ام ِة{ }1او اَل ُأ ْق ِس ُم ِِبلن ْف ِس اللوا امة{}2 777777777777777777777777 777777777777777777777777اين عا اَل َأ ا َْي اس ُب ْاَلن اس ُان َألن ا ْن اَم اَ ِِ اَا ام ُُ{ }3ب ا اَل قاا ِد ِر ِ ُّ َ ب ن } 4 { ُ ن ا ن ي و س ن أ ا ُ ِ ا ا ا ا 777777777777777777777777 7777777777777777777 Regions of Upper Limb The Pectoral (or Shoulder) Girdle Pectoral Girdle clavicle scapula humerus Clavicle The clavicle is an s-shaped bone that attaches the trunk to the upper extremity Medial 2/3 convex forward and lateral 1/3 concave forward Clinical Connection – Fractured Clavicle A fall on an outstretched arm (F.O.O.S.H.) injury can lead to a fractured clavicle The clavicle is weakest at the junction of the two curves Forces are generated through the upper limb to the trunk during a fall Therefore, most breaks occur approximately in the middle of the clavicle Acromial end – is flat and has a small facet for articulation with the acromion Sternal end – has a large facet for articulation with the manubrium, and first costal cartilage Conoid tubercle – Attachment of conoid ligament of the coracoclavicular ligament Trapezoid line – Attachment of trapezoid portion of the coracoclavicular ligament Functions Of The Clavicle Cleidocranial Dysostosis Serves as a strut from which the scapula and free limb are suspended, keeping them away from the thorax so that the arm has maximum freedom of motion Forms one of the bony boundaries of the cervico-axillary canal, affording protection to the neurovascular bundle supplying the upper limb Transmits shocks (traumatic impacts) from the upper limb to the axial skeleton Provides attachment for muscles Ossification Of The Clavicle The clavicle is the first long bone to ossify, beginning during the 5th and 6th embryonic weeks Is completed it between the 25th and 31st years. This is the last of the epiphyses of long bones to fuse. A smaller scale-like epiphysis may be present at the acromial end of the clavicle; it must not be mistaken for a fracture. Clavicle: Ligament Attachments Sternal end of clavicle to first costal cartilage: Costoclavicular ligament Conoid tubercle: Conoid portion of coracoclavicular ligament Trapezoid line: Trapezoid portion of coracoclavicular ligament Clavicle: Muscle Attachments Deltoid Pectoralis major Trapezius Sternocleidomastoid Subclavius Muscular, ligamentous, and fascial attachments to the clavicle Clavicle Clavicle Fracture The clavicle is one of the most commonly fractured bones in the body with indirect trauma being the usual cause (Sport injuries) Midclavicular fractures account for 80% of clavicular fractures, with distal fractures at 15% and proximal fractures at 5%. Complications of Clavicle Fracture Rare but serious neurovascular complication, such as a tear of the subclavian artery or brachial plexus injury, must be kept in mind when evaluating and treating clavicular fractures Neurovascular examination on initial evaluation is very important carefully evaluation of: – Pulses in the distal part of the upper extremity – Strength – Sensation The close relationship of the supraclavicular nerves to the clavicle may result in their involvement in callus formation after fracture of the bone. This may be the cause of persistent pain over the side of the neck. A fracture through the clavicle causes the shoulder to sag forward and downward. Because of the weight of the upper limb the trapezius muscle is unable to hold the lateral fragment up so the shoulder drops The sternodeidomastoid muscle elevates the medial fragment of bone The lateral fragment of the clavicle may be pulled medially by the adductor muscles of the arm, such as the pectoralis major. Overriding of the bone fragments shortens the clavicle. Treatment and Prognosis Most fractures of the clavicle heal well Mid and proximal clavicular fractures are usually treated using figure-of-eight strapping Immobilization is usually discontinued at 3-4 weeks The Thoracic Outlet Syndrome The thoracic outlet contains: – – – – – The first rib The subclavian artery and vein The brachial plexus The clavicle The lung apex. Injury to these structures may result in postural or movement-induced pain around the shoulder and supraclavicular region Most of the symptoms are caused by pressure on the lower trunk of the plexus producing pain down the medial side of the forearm and hand and wasting of the small muscles of the hand. Pressure on the blood vessels may compromise the circulation of the upper limb. Cervical rib Scapula Flat triangular bone On the posterior thoracic wall Between 2nd and 7th rib Anterior Scapula Borders: – Superior – Medial – lateral Angles: • Superior • inferior coracoid process acromion neck of scapula Anterior Scapula coracoid process acromion process glenoid cavity superior angle subscapular fossa inferior angle Subscapular fossa – Origin of the subscapularis muscle Suprascapular notch – The superior transverse scapular ligament traverses this notch. • The suprascapular artery passes over it • The suprascapular nerve passes under the ligament. Posterior Scapula Spine of scapula – Divides the supraspinous and infraspinous fossae – Serves as attachment for the deltoid and trapezius Acromion: – Lateral extension of spine of scapula; – Articulate with clavicle Greater scapular notch – Point at which the spine of the scapula ends, but the acromion continues; Coracoid process – Partially seen as it projects anteriorly; Supraspinous fossa – Origin of the supraspinatus muscle Infraspinous fossa – Origin of the infraspinatous muscle Lateral border – Attachment of: • Teres major • The long head of the triceps brachii • Teres minor Posterior Scapula acromion process supraspinous fossa infraspinous fossa spine lateral border medial border Lateral Scapula Supraglenoid tubercle – Attachement of the long head of the biceps brachii Infraglenoid tubercle – Attachement of the long head of the triceps brachii Lateral Scapula Acromion: – Articulates with the clavicle – Attachment for the trapezius and deltoid muscles; Superior and inferior angles Coracoid process: – Attachment point for: • The short head of the biceps brachii • Corachobrachialis • Pectoralis minor Muscular and ligamentous attachments, costal aspect of scapula Muscular and ligamentous attachments, dorsal aspect of scapula Fracture Of The Scapula Many fractures of the scapula result from high-impact accidents – such as being thrown from a motorcycle 9/10 of those with fractures of the scapula also suffer from life-threatening injuries – rib fractures – lung injuries – head and spinal cord injuries. Fracture Of The Scapula The diagnosis of a fracture of the body of the scapula is often overlooked If the fracture is not associated with other life-threatening injuries – a sling or shoulder immobilizer may be used for 1-to-2 weeks until the pain subsides. Winged Scapula The serratus anterior muscle (innervated by long thoracic nerve) pulls the medial border of the scapula to the posterior thoracic wall and stabilizes it Winged Scapula When the serratus anterior is paralyzed the medial border of the scapula moves laterally and posteriorly away from the thoracic wall This giving the scapula the appearance of a wing, consequently the term “winged scapula”] Weakness or paralysis of serratus anterior may be secondary to: – Lesions of the 5/6/7 cervical nerve roots (injury or viral neuropathy) – Injury to the brachial plexus – Direct damage to the long thoracic nerve • Weapons, including missiles (bullets) directed toward the thorax, are a common source of injury A way to check if the muscle is working properly is to have a person push against a wall or door When the arm is raised, the medial border and inferior angle of the scapula pull markedly away from the posterior thoracic wall Disability is rare however if function is noticeably impaired – Transfer of sternal portion of pectoralis major via a fascia lata graft to the lower pole of the scapula – The scapula can be fixed to the rib cage The Humerus The humerus is the bone of the shoulder and arm. It articulates with the scapula at the shoulder and with the radius and ulna at the elbow. The proximal end consists of: – The head – Anatomical neck – Greater and lesser tubercles separated from each other by an intertubercular groove (bicipital groove) The head The head, nearly hemispherical in form Directed upward, medialward, and a little backward Articulates with the glenoid cavity of the scapula . The circumference of its articular surface is slightly constricted and is termed the anatomical neck The anatomical neck The anatomical neck of the humerus is an indentation no suremuh eht fo daeh eht ot latsid eht hcihwarticular capsule attaches. It is best marked in the lower half of its circumference In the upper half it is represented by a narrow groove separating the head from the tubercles . Fracture of the anatomical neck rarely.srucco The Greater Tubercle The greater tubercle is situated lateral to the head and lesser tubercle, and just lateral to the anatomical neck It is covered by the deltoid muscle, which is responsible for the normal, rounded contour of the shoulder. Its upper surface is rounded and marked by three flat impressions: – the highest for insertion of the suprasinatus muscle – the middle for the infraspinatus muscle – the lowest one, and the body of the bone for teres muscle The lateral surface of the greater tubercle is convex, rough, and continuous with the lateral surface of the body The Lesser Tubercle The lesser tubercle is more prominent than the greater tubercle It is situated in front, and is directed medialward and forward . Above and in front it presents an impression for the insertion of the tendon of the subscapularis muscle The Intertubercular (Bicipital) Groove The tubercles are separated from each other by a deep groove, the intertubercular groove (bicipital groove gnol eht segdol hcihw ,) iihcarb specib eht fo nodnet elcsum Its lower portion gives insertion to the tendon of the latissimus dorsi muscle . Its lips are called, respectively, the crests of the greater and lesser tubercles (bicipital ridges( The surgical neck The surgical neck is the point distal to the tubercles at which the superior portion of the bone meets the shaft The surgical neck is a common site of fracture . It makes contact with the axillary nerve dna ehtposterior humeral circumflex artery The body of the humerus has two prominent features: – The deltoid tuberosity, laterally, for attachment of the deltoid muscle – The oblique radial groove, posteriorly, in which the radial nerve and deep artery of the arm lie as they pass between the medial and the long and then the lateral heads of the triceps brachii muscle. Anterior Humerus medial epicondyle trochlea coronoid fossa capitulum lateral epicondyle deltoid tuberosity intertubercular groove lesser tubercle greater tubercle Humeral Head Fracture Anterior or posterior shoulder dislocation may result in a compression fracture of the humeral head The fibrocartilaginous glenoid labrum of scapula produces the fracture Glenoid labrum can become jammed in the fracture, making reduction difficult Avulsion fractures of the greater tubercle of the humerus Relatively common, especially in middle-aged and elderly people. In younger people, results from a fall on the hand when the arm is abducted. Muscles (especially the subscapularis) remaining attached to the humerus pull the limb into medial rotation An inferior dislocation of the shoulder joint often occurs in the absence of the muscle attachments to the greater tubercle. Surgical Neck Fractures Most injuries of the proximal end of the humerus are fractures of the surgical neck. These injuries are common in elderly people, especially those with osteoporosis The injuries usually result from a minor fall on the hand, with the force being transmitted up the forearm bones of the extended limb. Humeral Shaft Fracture Usually result from a direct blow, a fall, an automobile injury, or a crushing injury. Missiles from firearms or shell fragments may pierce the arm and cause an open fracture. Other indirect means of injury, such as a fall on an outstretched upper extremity or violent muscle contracture Because the humerus is surrounded by muscle and has a well-developed periosteum, the bone fragments usually unite well. Humeral Shaft Fracture Fracture above the level of pectoralis major – proximal fragment abduct and rotate internally due to the action of the rotator cuff Fracture above the deltoid and below pectoralis major – deltoid pulls the distal fragment laterally, pectoralis major pulls the proximal fragment medially Fracture below deltoid – proximal fragment abducts due to deltoid, distal fragment pulled medially and proximally by biceps/ brachialis and coracobrachialis The axillary nerve lies in contact with the surgical neck The radial nerve runs inferiorward and lateral on the posterior surface (Spiral groove) The ulnar nerve lies in a groove posterior to the medial epicondyle and is palpable there ("funny bone") Because of their contact with the humerus, the axillary, radial, and ulnar nerves may be injured in fractures of the surgical neck, shaft, and medial epicondyle, respectively. Imaging the shoulder a. b. c. d. e. AP external rotation AP internal rotation Y-view (transthoracic) Axillary Acromioclavicular Imaging the shoulder AP external rotation This view is taken with the patient in the anatomical position. The arm is externally rotated so that the thumbs point laterally. 1. Clavicle 2. Acromioclavicular joint 3. Acromion 4. Greater tubercle of humerus 5. Head of humerus 6. Lesser tubercle of humerus 7. Surgical neck of humerus 8. Coracoid process 9. Glenoid fossa 10. Shoulder joint 11. Lateral border of scapula Imaging the shoulder AP internal rotation This view is taken with the arm internally rotated Lateral View Coracoid (Anterior) Spine (Posterior) "Y“ figure is made by: B o d y the spine of the scapula the coracoid the scapular body Imaging the shoulder Y-view (transthoracic) The Y-view is taken by aligning the plane of the scapula parallel with the x-ray beams so that it can be seen "floating" over the thoracic rib cage. the humeral head should be in alignment with the glenoid fossa of the scapula. Structures that can be identified: – – – – – – – spine of the scapula body of scapula Coracoid humeral head glenoid fossa the humeral shaft the clavicle Imaging the shoulder Axillary view The x-ray beam is directed either up into the axilla (inferior to superior), or from the superior aspect of the shoulder down through the axilla (superior to inferior). Visualizing whether the humeral head is within, or posterior to, the glenoid fossa. Anterior or posterior shoulder dislocations can be occult on AP films, making the axillary view necessary. Shoulder Imaging Transthoracic Lateral Projection Transthoracic Lateral Shoulder