ANA 211 Bones of the Upper Limb PDF

ANA 211-Bones of the Upper Limb BY S. I. DAVID DEPARTMENT OF ANATOMY FACULTY OF BASIC MEDICAL SCIENCES COLLEGE OF MEDICINE AND HEALTH SCIENCES BINGHAM UNIVERSITY, NEW KARU, NASARAWA STATE ...

ANA 211-Bones of the Upper Limb BY S. I. DAVID DEPARTMENT OF ANATOMY FACULTY OF BASIC MEDICAL SCIENCES COLLEGE OF MEDICINE AND HEALTH SCIENCES BINGHAM UNIVERSITY, NEW KARU, NASARAWA STATE  2 Introduction  The upper limb is divided into; pectoral girdle, arm, forearm and the hand  Pectoral/shoulder girdle- clavicle and scapula  Arm/brachium- humerus  Forearm/antebrachium- radius and ulna bones  Hand- carpal bones, metacarpals and phalanges  3 Clavicle (collar bone)  S-shaped bone  Connects the upper limb to axial skeleton  Has a forward-facing convex part medially and a forward facing concave part laterally  Has 2 extremity/end 1. Quadrangular medial sternal extremity connects to the manubrium of sternum & first costal cartilage 2. Flat lateral acromial extremity connects to acromium of scapula  The superior surface is smoother than the inferior surface  4 Clavicle (collar bone)  Costal tuberosity/impression for the costoclavicular ligament on the inferior surface of the sternal extremity  Conoid tubercle and the trapezoid line, inferiorly at the acromial end for attachment of the coracoclavicular ligament  It has the subclavian groove in the medial third of it’s shaft for attachment of the subclavius muscle  5 Ossification of the clavicle  First bone to begin ossification during foetal development, and the last one to complete ossification, at approximately 21 years of age  Only long bone to be ossified intramembranously, except for its medial end  It ossifies from two primary centres (in the shaft between the 5th and 6th weeks of intrauterine life, and fuse about the 45th day) and  one secondary centre for the medial end (appears during 15-17 years, and fuses with the shaft during 21-22 years).  6 Fracture of the clavicle  The weakest point along the clavicle is the junction of the middle and outer third.  Transmission of forces to the axial skeleton in falls on the shoulder or hand may prove greater than the strength of the bone at this site and this indirect force is the usual cause of fracture.  When fracture occurs, the trapezius is unable to support the weight of the arm so that the characteristic picture of the patient with a fractured clavicle is that of a man supporting his sagging upper limb with his opposite hand.  The lateral fragment is not only depressed but also drawn medially by the shoulder adductors, principally the teres major, latissimus dorsi and pectoralis major  7 Fracture of the clavicle…  It may cause injury to the brachial plexus (lower trunk), causing paresthesia (sensation of tingling, burning, and numbness) in the area of the skin supplied by medial brachial and antebrachial cutaneous nerves  May also cause fatal haemorrhage from the subclavian vein and is responsible for thrombosis of the subclavian vein, leading to pulmonary embolism  8 Scapula  Large, flat triangular bone  Extends from the 2nd-7th rib It has  three angles (lateral, superior, and inferior)  three borders (superior, lateral, and medial)  two surfaces (costal and posterior)  three processes (acromion, spine, and coracoid process)  9 Borders and angles of the scapula  The medial/vertebral border- nearest to the vertebral column (approx. 5cm away from spinous process of thoracic vertebrate)  The lateral border- directed toward the arm is the thickest border  Along the superior border, a distinct depression called the (supra)scapular notch is a passageway for the suprascapular nerve.  The superior angle- between the superior and medial borders  The inferior angle- between the medial and lateral borders  The lateral angle- between the superior and lateral borders has the glenoid fossa for articulation of head of humerus 10 11  12 Surfaces/features of the scapula  Anterior surface- slightly concave area known as the subscapular fossa where the subscapularis muscle lies  The spine- the prominent diagonal bony ridge seen on the posterior surface  The deltoid tubercle- prominence indicating the medial point of attachment of the deltoid located on the spine  Above the spine is the supraspinous fossa, and below the spine is the infraspinous fossa.  Glenoid cavity/fossa- a shallow depression inferior to the acromion into which the head of the humerus fits.  13 Surfaces/features of the scapula…  Supraglenoid tubercle- located superior to the glenoid cavity, is the site of attachment for the long head of the biceps brachii.  Infraglenoid tubercle- A large triangular-shaped roughening inferior to the glenoid cavity, attachment for the long head of the triceps brachii  The acromion- the broadened part of the spine serves for the attachment of several muscles and articulation with the clavicle.  The coracoid process- thick upward projection lying superior and anterior to the glenoid cavity.  14 Ossification of the scapula  The scapula ossifies from one primary centre and seven secondary centres.  The primary centre appears near the glenoid cavity during the 8th week of development. Secondary centre appears  in the middle of the coracoid process during the first year and fuses by the 15th year.  in the root of the coracoid process (subcoracoid centre) during the 10th year and fuses by the 16th to 18th years  At two sites for the acromion, one for the lower two- thirds of the margin of the glenoid cavity, one for the medial border and one for the inferior angle, appear at  15 Humerus  Longest bone of the upper limb, consists of proximal end, shaft and distal end Proximal end  The head- half-spherical in shape, projecting supero-medially  The anatomical neck- a narrow constriction immediately distal to the head indicating the line of attachment of the glenohumeral joint capsule. Laterally lies between the head and the greater and lesser tubercles, and medially between the head and the shaft  The greater and lesser tubercles- prominent landmarks for attachment of the four rotator cuff muscles of the glenohumeral joint  the superior facet of greater tubercle- for supraspinatus  the middle facet of greater tubercle- for infraspinatus  the inferior facet of greater tubercle- for teres minor  large smooth impression of lesser tubercle- for subscapularis  16 Humerus…  17 Humerus…  Intertubercular sulcus (bicipital groove)- separates the lesser and greater tubercles and continues inferiorly onto the proximal shaft, allows for passage of tendon of the long head of the biceps brachii  The sulcus has a lateral lip, medial lips and floor for the attachment of the pectoralis major, teres major, and latissimus dorsi muscles, respectively  The lateral lip continues to join the deltoid tuberosity for insertion of deltoid muscle  Approximately in same position but medial to the deltoid tuberosity is the site for attachment of coracobrachialis  Between the proximal end and the shaft is the surgical neck where 18  19 Shaft of the humerus  Triangular in cross-section, having 3 borders (anterior, lateral , and medial) and 3 surfaces (anterolateral, anteromedial, and posterior)  On the posterior surface is the site of the attachment of the lateral head of the triceps brachii  Aside the deltoid tuberosity the shaft of the humerus has the oblique radial groove posteriorly, for the passage of radial nerve and deep artery of the arm.  Distally, the shaft becomes flattened, and these expands as the lateral and medial supraepicondylar/supracondylar ridge which ends as the prominent medial epicondyle and the lateral epicondyle, providing for muscle attachment 20  21 Distal end of the humerus  It bears a condyle, two epicondyles, and three fossae The condyle has two articular parts  the lateral capitulum hemispherical in shape, projecting anterio-inferiorly articulates with the radius and  The medial trochlea pulley shaped and extends to the posterior surface, articulates with the ulna The 3 fossae are  The radial fossa- located superior to the capitulum anteriorly accommodates the edge of the head of the radius when the forearm is fully flexed  The coronoid fossa- located anteriorly receives the coronoid process of the ulna during full flexion of the elbow  The olecranon fossa- located posteriorly accommodates the olecranon of  22 Distal end of the humerus…  23 Ossification of the humerus  The humerus ossifies from one primary centre and 7 secondary centres  The primary centre appears in the middle of the diaphysis during the 8th week of development  The upper end ossifies from 3 secondary centres: at the head (first year), the greater tubercle (2nd year), and the lesser tubercle (5th year). All 3 fuses as one epiphysis at the 6th year and then with the shaft the 20th year.  The lower end ossifies from 4 centres which form 2 epiphyses. One for the capitulum and the lateral flange of the trochlea (1st year), the medial flange of the trochlea (9th year), the lateral epicondyle (12th year): all 3 fuse at the 14th year to form one epiphysis, and then the shaft at about 16 years.  24 Fracture of the humerus  At the surgical neck- Because the surgical neck is weaker than more proximal regions of the bone, it is one of the sites where the humerus commonly fractures. The associated nerve (axillary) and artery (posterior circumflex humeral) can be damaged by fractures in this region.  Fracture of the shaft may injure the radial nerve and deep brachial artery in the spiral groove.  Supracondylar fracture is a fracture of the distal end of the humerus; it is common in children and occurs when the child falls on the outstretched hand with the elbow partially flexed and may injure the median nerve.  The distal fragment and its soft tissues are pulled posteriorly by the triceps muscle, effectively it “ bowstrings ” the brachial artery over the irregular proximal fracture fragment. In children, the muscles of the anterior compartment of the forearm are rendered ischemic and form severe contractions, significantly reducing the function of the anterior compartment and flexor muscles (Volkmann’s ischemic contracture).  Fracture of the medial epicondyle may damage the ulnar nerve. This nerve  25 Ulna  The proximal end of the ulna articulates with the humerus and radius.  Trochlear notch- a distinct depression which articulates with the trochlea of the humerus.  The coronoid process- forms the anterior lip of the trochlear notch  The olecranon- its anteriolateral surface forms the posterior portion of the trochlear notch. The superior surface has an impression for the attachment of the triceps brachii. The posterior surface can be palpated as the “ tip of the elbow”  Lateral and inferior to the coronoid process is the radial notch, which accommodates the head of the radius.  Ulnar tuberosity- site for the brachialis muscle  26 Ulna… The shaft of the ulna is triangular in cross-section and has: three borders (anterior, posterior, and interosseous)  The anterior border is smooth and rounded.  The posterior border is sharp and palpable along its entire length.  The interosseous border is also sharp and is the attachment site for the interosseous membrane, which joins the ulna to the radius three surfaces (anterior, posterior, and medial)  The anterior surface of the ulna is smooth, except distally where there is a prominent linear roughening for the attachment of the pronator quadratus muscle.  The medial surface is smooth and unremarkable.  The posterior surface is marked by lines, which separate different regions of  27 Ulna… Distal end of the ulna  The distal end of the ulna is small and characterized by a rounded head and the ulnar styloid process  The anterolateral and distal part of the head is covered by articular cartilage.  The ulnar styloid process originates from the posteromedial aspect of the ulna and projects distally.  The ulna does not reach—and therefore does not participate in—the  28 Ossification of ulna  The shaft and most of the upper end ossify from a primary centre which appears during the 8th week of development.  The superior part of the olecranon ossifies from a secondary centre which appears during the 10th year and joins the rest of the bone by 16 years.  The lower end ossifies from a secondary centre which appears during the 5th year, and joins with the shaft by 18 years.  This is the growing end of the bone  29 Radius  It has a small proximal end, a body and a large distal end Proximal end  has a proximal disc-shaped head that articulates with the capitulum of the humerus and the radial notch of the ulna.  The neck of the radius is a short and narrow cylinder of bone between the expanded head and the radial tuberosity on the shaft  Has a prominent radial tuberosity, for attachment of the biceps brachii, located on the medial side of the body, just below the head.   30 Radius…  Throughout most of its length, the shaft of the radius is triangular in cross-section, with: three borders (anterior, posterior, and interosseous)  The anterior border begins on the medial side of the bone as a continuation of the radial tuberosity. In the superior third of the bone, it crosses the shaft diagonally, from medial to lateral, as the oblique line of the radius.  The posterior border is distinct only in the middle third of the bone.  The interosseous border is sharp and is the attachment site for the interosseous membrane, which links the radius to the ulna. three surfaces (anterior, posterior, and lateral)  The anterior and posterior surfaces of the radius are generally smooth,  31 Radius… Distal end  On the distal end of the radius is a double-faceted surface for articulation with the proximal carpal bones (scaphoid and lunate).  The distal end of the radius also has a styloid process on the lateral tip and an ulnar notch on the medial side that receives the distal end of the ulna.  The styloid processes on the ulna and radius provide lateral and medial stability for articulation at the wrist.  The posterior surface of the radius is characterized by the presence of a large dorsal tubercle , which acts as a pulley for the tendon of one of the extensor pollicis longus 32 33  34 Ossification of the radius  The shaft ossifies from a primary centre which appears during the 8th week of development.  The lower end ossifies from a secondary centre which appears during the first year and fuses at 20 years; it is the growing end of the bone.  The upper end (head) ossifies from a secondary centre which appears during the 4th year and fuses at 18 years  35 Colle’s fracture  Colles’s fracture of the wrist is a distal radius fracture in which the distal fragment is displaced (tilted) posteriorly, producing a characteristic bump described as dinner (silver) fork deformity because the forearm and wrist resemble the shape of a dinner fork.  If the distal fragment is displaced anteriorly, it is called a reverse Colles’s fracture (Smith’s fracture).  It is often comminuted (broken into pieces).  The fracture results from forced dorsiflexion of the hand, usually as the result of trying to ease a fall by outstretching the upper limb.  This fracture may show styloid processes of the radius and ulna line up on a radiograph.  36 Fracture of the head of radius  A fracture of the head of radius is a common injury and can cause appreciable morbidity.  It is one of the typical injuries that occur with a fall on the outstretched hand.  On falling, the force is transmitted to the radial head, which fractures.  These fractures typically result in loss of full extension, and potential surgical reconstruction may require long periods of physiotherapy to obtain a full range of movement at the elbow joint.