Osteology Of The Upper Limb PDF

The Upper Limb: Osteology Prof. Oluwadiya Kehinde www.oluwadiya.com  Introduction The bones of the upper limb can be divided into four main groups: i. the shoulder girdle ii. arm iii. forearm and iv. hand In contrast to the lower limb (which is...

The Upper Limb: Osteology Prof. Oluwadiya Kehinde www.oluwadiya.com  Introduction The bones of the upper limb can be divided into four main groups: i. the shoulder girdle ii. arm iii. forearm and iv. hand In contrast to the lower limb (which is involved in weight-bearing and locomotion), the main role of the upper limb is to control the position of the hand in space – enabling manipulation of objects in the environment.  Bones of the Upper Limb 32 bones in all Shoulder Girdle - Clavicle (Collar Bone) Scapula (Shoulder Blade) Arm Humerus Forearm Radius (Lateral bone of forearm) Ulna (Medial bone of forearm) Hand Carpal Bones (8) Metacarpals (5) Phalanges (14) 3 BONES OF THE SHOULDER GIRDLE  CLAVICLE Longest horizontal bone in the body. Anterior to the root of neck. “S” shaped bone subcutaneous throughout its length. 1st bone to ossify (5-6th week of fetal life) FUNCTIONS :- Attaches the upper limb to the trunk as part of the shoulder girdle Transmit weight of upper limb to the trunk Protects the underline neurovascular structures 5  CLAVICLE PARTS :- 1. SHAFT a) Lateral 1/3 (Flattened) b) Medial 2/3 (cylindrical shape) 2. ACROMIAL END Flattened with small oval facet Articulates with acromion process of scapula (Acromioclavicular joint) 3. STERNAL END Quadrangular and expanded, upper part rough Articulates with manubrium sterni (Sternoclavicular joint) 6  Clavicle: Clinical Relevance Fractures are the most common clinical presentation of the clavicle This is because: – The clavicle acts to transmit forces from the upper limb to the axial skeleton. – It is relatively small size 15% of fractures occur in the lateral third 80% occur in the middle third 5% occur in the medial third. Clavicle Sternoclavicular Joint (SC) 1= Costoclavicular ligament 2= Anterior sternoclavicular ligament 3= Interclavicular ligament Acromioclavicular Joint (AC)  Scapula Also known as the shoulder blade. It articulates with: I. the humerus at the glenohumeral joint II. the clavicle at the acromioclavicular joint. In doing so, the scapula connects the upper limb to the trunk It serves as a site for attachment for seventeen muscles  SCAPULA Surfaces : Three surfaces 1. COSTAL SURFACE:  Costal because it faces the ribs  Faces forward and medially  Largely made of a concave and hollow part  This concave and hollow part is called the subscapular fossa  The subscapularis (rotator cuff muscle) originates from this fossa.  Coracoid process:  originates from the superolateral surface of the costal scapula  Hook-like projection, which lies just underneath the clavicle.  The pectoralis minor attaches here  The coracobrachialis and biceps brachii (short head) muscles 12 originates here  SCAPULA: Dorsal Surface  It is divided in to 2 halves by the spine of scapula.  Upper small part is called the supraspinous fossa. The supraspinous muscle originates here  Lower large part is called the infraspinous fossa. The infraspinatus muscle originates from this area  Both fossae communicate with each other through the spinoglenoid notch  Acromion – projection of the spine that arches over the glenohumeral joint and articulates with the clavicle at the acromioclavicular joint 13  Scapula: Lateral Surface Faces the humerus. Site of the glenohumeral joint Glenoid fossa – a shallow cavity, located superiorly on the lateral border. – It articulates with the head of the humerus to form the glenohumeral (shoulder) joint. Supraglenoid tubercle – a roughening immediately superior to the glenoid fossa. – The place of attachment of the long head of the biceps brachii. Infraglenoid tubercle – a roughening immediately inferior to the glenoid fossa. – The place of attachment of the long head of the triceps brachii.  SCAPULA: BORDERS BORDERS : Three borders 1. LATERAL BORDER : o Thickest border o Extends from glenoid cavity to inf. angle 2. MEDIAL BORDER : o Longest border o Extends from superior angle to inferior angle. 3. UPPER BORDER : o Thinnest & shortest border o Extends from superior angle to supra scapular notch. 15 Scapula Scapula Scapula  Scapula: Clinical Relevance Fractures – Relatively uncommon – Indication of severe chest trauma. Winged Scapula: – Due to injury to long thoracic nerve which innervates the serratus anterior muscle – Causes the scapula to protrude out of the back when pushing with the arm.  HUMERUS Longest and strongest bone of upper limb PARTS : 1. Proximal end 2. Shaft 3. Distal end 20 HUMERUS: Proximal End  Head: Fits into the glenoid cavity of the scapula. Faces medially, upwards and backwards  Neck Anatomical neck: Separates the head from the tuberosities Surgical neck: Most prone to fractures, hence the name  Greater tuberosity: Most lateral part of the proximal end. serves as an attachment site for three of the rotator cuff muscles – supraspinatus, infraspinatus and teres minor  Lesser tuberosity: Provides attachment for the subscapularis  intertubercular (Bicipital) groove(Sulcus): The tendon of the long head of the biceps brachii emerges from the shoulder joint and runs through this groove 21  HUMERUS: Proximal End The edges of the intertubercular sulcus are known as lips. Pectoralis major attaches to lateral lip Teres major to medial lip Latissimus dorsi in between them (mnemonic = “a lady between two majors”)  Humerus: Shaft Deltoid tuberosity: On the lateral side of the humeral shaft, roughed for the attachment of the deltoid muscle Radial (or spiral) groove is a shallow depression that runs diagonally down the posterior surface of the humerus, parallel to the deltoid tuberosity. The radial nerve and profunda brachii artery lie in this groove. The following muscles attach to the humerus along its shaft: o Anteriorly – coracobrachialis, deltoid, brachialis, brachioradialis. o Posteriorly – medial and lateral heads of the triceps (the spiral groove lies between their origins).  HUMERUS: DISTAL END A) Articular part  Capitulum: for the radius  Trochlea; for the ulna B) Non-articular Part  Medial Epicondylar Ridge  Lateral epicondylar ridge: rougher, serves as attachment for the forearm extensors  Lateral Epicondyle  Medial Epicondyle: larger of the two and extends more distally. The ulnar nerve passes in a groove on the posterior aspect of the medial epicondyle where it is palpable  Olecranon Fossa: posterior, accommodates olecranon at full extension  Coronoid Fossa: Anterior: accommodates the coronoid process of the ulna at full flexion  Radial Fossa: Anterior 24 Humerus: Distal end  Humerus: Clinical Relevance Mid-shaft fracture of the humerus can injure the radial nerve and profunda brachii artery (both in the radial groove). Symptoms of radial nerve damage The nerve innervates the extensors of the wrist. When the nerve is damaged, either direct or as a consequence of swelling, the extensors will be paralysed. This results in unopposed flexion of the wrist, causing a ‘wrist drop’. There can also be some sensory loss over the dorsal surface of the hand, and the proximal ends of the lateral three and a half fingers dorsally.  Humerus: Clinical Relevance The fracture is typically transverse or Supracondylar fracture: oblique, and the most common fracture of the distal mechanism of injury is falling on an outstretched hand. It is more humerus just above the common in children than adults elbow joint. Following structures can be damaged: Brachial artery can be damaged directly or via swelling following the trauma. The resulting ischaemia can cause Volkmann’s ischaemic contracture – uncontrolled flexion of the hand – as flexor muscles become fibrotic and short. Nerves: i. Anterior interosseous nerve (branch of the median nerve), ii. Ulnar nerve or iii. Radial nerve  Humerus: Articulations The proximal region of the humerus articulates with the glenoid fossa of the scapula to form the glenohumeral joint (shoulder joint). Distally, at the elbow joint, the capitulum of the humerus articulates with the head of the radius and the trochlea of the humerus articulates with the trochlear notch of the ulna Glenohumeral Joint (Shoulder) Labrum Shoulder (anterior) Shoulder (anterior) Shoulder Girdle (Internal Rotation) Shoulder Girdle (External Rotation) Shoulder Girdle (Axillary) THE FOREARM BONES  RADIUS It lies laterally and parallel to ulna The second of the forearm bones. The radius pivots around the ulna to produce movement at the proximal and distal radio-ulnar joints. 37  Proximal Region of the Radius The proximal end of the radius articulates in both the elbow and proximal radioulnar joints. Important bony landmarks include: Head of radius – A disk shaped structure, with a concave articulating surface. It is thicker medially, where it takes part in the proximal radioulnar joint. Neck – A narrow area of bone, which lies between the radial head and radial tuberosity. Radial tuberosity – A bony projection, which serves as the place of attachment of the biceps brachii muscle.  Shaft of the Radius The radial shaft expands in diameter as it moves distally. Like the ulna, it is triangular in shape, with three borders and three surfaces. In the middle of the lateral surface, there is a small roughening for the attachment of the pronator teres muscle.  Distal End of the Radius In the distal region, the radial shaft expands to form a rectangular end. The lateral side projects distally as the styloid process. Ulnar notch: concavity in the medial surface, articulates with the head of ulna to form the distal radioulnar joint. Wrist joint: The distal surface of the radius has two facets, for articulation with the scaphoid and lunate carpal bones. This makes up the  Articulations of the Radius The radius articulates in four places: i. Elbow joint – Partly formed by an articulation between the head of the radius, and the capitulum of the humerus. ii. Proximal radioulnar joint – An articulation between the radial head, and the radial notch of the ulna. iii. Wrist joint – An articulation between the distal end of the radius and the carpal bones. iv. Distal radioulnar joint – An articulation between the ulnar notch and the head of the ulna.  RADIUS: Clinical Relevance Colles’ Fracture – The most common type of radial fracture. A fall onto an outstretched hand causing a fracture of the distal radius. The structures distal to the fracture (wrist and hand) are displaced posteriorly. It produces what is known as the ‘dinner fork deformity’. Fractures of the radial head – This is Colles’s Fracture characteristically due to falling on an outstretched hand. The radial head is forced into the capitulum of humerus, causing it to fracture. Smith’s Fracture – A fracture caused by falling onto the back of the hand. It is the opposite of a Colles’ fracture, as the distal fragment is now placed anteriorly. Smith’s Fracture 42  Ulna The medial of the forearm bones Acts as the stabilising bone, with the radius pivoting to produce forearm movement.  Ulna: Proximal End Olecranon – a large projection of bone that extends proximally, forming part of trochlear notch. It can be palpated as the ‘tip’ of the elbow. The triceps brachii muscle attaches to its superior surface. Coronoid process – this ridge of bone projects outwards anteriorly, forming part of the trochlear notch. Trochlear notch – formed by the olecranon and coronoid process. It articulates with the trochlea of the humerus. Radial notch – located on the lateral surface of the trochlear notch, this area articulates with the head of the radius. Anterior Tuberosity of ulna – a roughening immediately distal to the coronoid process. It is where the brachialis muscle attaches.  Ulna: Shaft Triangular in shape As it moves distally, it decreases in width. Three surfaces: i. Anterior – site of attachment for the pronator quadratus muscle distally. ii. Posterior – site of attachment for many muscles. iii. Medial – unremarkable. Three borders: i. Posterior – palpable along the entire length of the forearm posteriorly ii. Interosseous – site of attachment for the interosseous membrane, which spans the distance between the two forearm bones. It is the sharpest border, and most lateral iii. Anterior – unremarkable.  Ulna: Proximal End and Articulations The proximal end of the ulna articulates with the trochlea of the humerus. It also articulates with the head of the radius to form the superior radio-ulna joint  Ulna: Distal End and Articulations The distal end of the ulna is much smaller in diameter than the proximal end. It terminates in a rounded head, with distal projection – the ulnar styloid process. The head articulates with the ulnar notch of the radius to form the distal radio-ulna joint.  Ulna: Clinical Relevance Lone Ulna Fracture – A fracture of the ulna alone (not involving the radius) usually occurs as a result of the ulna being hit by an object. The shaft is the most likely site of fracture. Commonly called nightstick fracture – Less commonly, the olecranon process can be fractured. This is caused by the patient falling on a flexed elbow. The triceps brachii can displace part of the fragments proximally. Both Bones. Fractures of both bones Fracture of one bone with dislocation of any of the radio-ulna joints There are two classical fractures: – Monteggia’s Fracture – Usually caused by a force from behind the ulna. The proximal shaft of ulna is fractured, and the head of the radius dislocates anteriorly at the elbow. – Galeazzi’s Fracture – A fracture to the distal radius, with the ulna head dislocating at the distal radio-ulnar joint.  X-ray of the Forearm (AnterioPosterior) view X-ray of the Forearm (lateral) View  Radius and Ulna Fracture Radius and Ulna Galleazzi’s Monteggia’s Fractures Fracture Fracture Elbow (Anterio-Posterior) Elbow (post) Elbow (ant) Elbow (lateral) Elbow (medial) Elbow (lateral) Olecranon Bursa BONES OF THE HAND  CARPAL BONES 8 IN 2 ROWS PROXIMAL ROW – 4 1. SCAPHOID – Boat Shaped 2. LUNATE - Semilunar 3. TRIQUETRAL - Pyramidal 4. PISIFORM - Sesamoid bone Pea Shaped DISTAL ROW – 4 1. TRAPEZIUM - 2. TRAPEZOID - 3. CAPITATE - 4. HAMATE - Has a hook Mnemonic: She Likes To Play, Try To Catch Her61  Carpal Bones Collectively, the carpal bones form an arch in the coronal plane. A membranous band, the flexor retinaculum, spans between the medial and lateral edges of the arch, forming the carpal tunnel. Proximally, the scaphoid and lunate articulate with the radius to form the wrist joint (also known as the ‘radio-carpal joint’). In the distal row, all of the carpal bones articulate with the metacarpals. To form the Carpometacarpal joints  Carpal Bones: Clinical Relevance The scaphoid bone of the hand is the most commonly fractured carpal bone In a fracture of the scaphoid, the characteristic clinical feature is pain and tenderness in the anatomical snuff box The scaphoid is at particular risk of avascular necrosis after fracture because of its ‘retrograde blood supply’ which enters at its distal end. This means that a fracture to the middle (or ‘waist’) of the scaphoid may interrupt the blood supply to the proximal part of the scaphoid bone rendering it avascular. Patients with a missed scaphoid fracture are likely to develop osteoarthritis of the wrist in later life.  METACARPALS Short long bones – 5 PARTS : 1. HEAD – lies distally 2. BASE – lies proximally 3. SHAFT – lies in the middle ARTICULATIONS : 1st – Trapezium 2nd – Trapezium + Trapezoid + Capitate+ 3rd Metacarpal 3rd – Capitate + 2nd Metacarpal + 4th Metacarpal 4th – Hamate + 3rd Metacarpal + 4th Metacarpal 5th – Hamate + 4th Metacarpal  Metacarpals: Clinical Relevance Boxer’s fracture – A fracture of the 5th metacarpal neck. It is usually caused by a clenched fist striking a hard object. The distal part of the fracture is displaced anteriorly, producing shortening of the affected finger. Bennett’s fracture – A fracture of the 1st metacarpal base, caused by axial loading on a partially flexed metacarpal. This fracture extends into the first carpometacarpal joint leading to instability and subluxation of the joint. As a result, it often needs surgical repair. Boxer’s Fracture Bennet's Fracture Bones of the Wrist Plain X-ray: Lateral View  PHALANGES OF THE HAND 14: 2+3+3+3+3 PARTS : 1. BASE – lies proximally 2. SHAFT – lies in the middle 3. HEAD – lies distally Bones of the Hand  THANK YOU PLEASE JOIN THE FORUM AT WWW.OLUWADIYA.COM TO ASK QUESTIONS 70