The Radius (Notes)

THE RADIUS1RADIIUSIt is the lateral bone of the forearm and is homologuswith the tibia of lower limb It has an upper roundedend, a lower broad end with a styloid process and a shaft.TYPETypical long bone, develops by Carrilagenous ossification.SITEIt is the lateral bone of forearm and lies parallel to ulnain supination but crosses it in pronationANATOMICAL POSITION AND SIDE DETERMINATIONThe side of radius can be determined by keeping the bonevertically in such a that:-1Narrow disc shaped way end (head) is directed upwards.2Sharpest border (Interosseous border) of the shaft is kept medialy.3Styloid process at lower end is directed laterally and prominenttubercle (Lister's tubercle) at lower end faces dorsally.4Convexity of Shaft faces laterally. and concave anterior surfaceof shaft faces anteriorly.GENERAL FEATURESForExamTHE UPPER ENDFormed of-head, neck and tuberosity.THE HEAD:(Disc shaped)1Concave upper surface articulates with the capitulum of humerus.(ii) Its circumference articulates partially with radial notch ofwina and partially with annular ligament of superior radio-ulnar joint.THE NECK1Constricted part just below the head.(1)Lower part of annular ligarrent is loosely attached to the neck.THE RADIAL TUBEROSITYi Lies below the medial part of neck.(ii (iii) Its post-rough part receives the insertion of the biceps tendon.Its it anterior from the Smooth biceps part tondon. is related to bursa separating THE RADIUS2THE SHAFT3 Barders3 Sin3 Borders and 3 Surfaces -DIPAHKAR RAY-INTEROSSEOUS BORDER(i) Sharpest border and is directed medially.(ii) Begins below the radial tuberosity and ends distally by dividinginto 2 lines enclosing a narrow triangular area above what notch.(iii) Upper 2/3 of this border gives attachment to interosseous membrane.ANTERIORBORDER (i) Begins anterolateral to radial tuberosity.(ii) Upper part is called the anterior oblique line.(iii) Lower part forms the sharp lateral margin of lower end.POSTERIOR BORDER(ii) Stants above postero inferior to radial tuberosity.(ii) Upper part is oblique post-oblique line)(iii) It ends below at the dorsal tubercle of lis ter.ANTERIOR SURFACE(i) Between the anterior and interosseous borders.(ii) Upper 1/3 presents a nutrient faramen (directed towards the elbow).POSTERIOR SURFACEIs rather flat and lies between posterior andinterosseous borders.LATERAL SURFACEIIIs convex and lies between the anterior andposterior borders.(ii) It presents a rough impression (pronator tuberosity ) at its middle.Human Anatomy For ExamTHE LOWER ENDIt is the widest part of radius It has 5 Surfaces and Syloid process.ANTERIOR SURFACESmooth and slightly concave.POSTERIOR SURFACEA prominent ridge called Dorsal Tubercle of Lister.Lateral Medial to the durial tubercle there is a wide groove.LATERAL SURFACE(i) Projects downwards beyond the rest of theto the dursal tubercle there are 2 grooves.be felt subcuteneously in the anatomical snuff Box.bone forming the Styloid Process, which can(ii) Sybid process of radius projects 1cm. below the sabid processof Ulna.(iii) It gives attachment to the lateral ligament of thewrist joint. THE RADIUS3INFERIOR SURFACESmooth, concave and is divided by a faintridge into:-Human Anasonny For Exam(i) Lateral Triangular Area:- Articulates with Scaphoid bone.(ii) Medial Quadrangular Area:- Articulates with Lunate bone.MEDIAL SURFACEIt is concare, forming the ulnar notch ofradius which articulates with the head of ulna (inferior radio ulnarjoing)The ridge at the lower margin of the notch gives attachmentto the base of the Triangular articular disc. of the inf radio ulnarjoint.MUSCLE ATTACHMENTDIPANIKAR RAY(A) BLCEPS TENDON :- Inseried in the posterior part of radial tuberosity.(B) MUSELES (3) ATTACHED - ANTERIOR ASPECT TO RADIUS(i) FLEXOR DIGITORIUM SUPERFICIALIS (radial head) - Arise from Oblique line,(ii) FLEXOR POLLIEIS LONGUS :- Arises from upper 2/3 of anterior surface(Ti)PRONATOR QUADRATUS:- Insertion - lower 1/4 of anterior surface raridas. (belowant obl line](c) MUSCLES (3) INSERTION - LATERAL ASPECT OF RADIUS(ii) d) SUPINATOR PRONATOR M. - Upper 1/3 of shaft (between ant and post oblique line)(ii) TERES - Pronator tuberosity (in middle of the lateral surface)D OBRACHIORADIALIS - Lower end of lateral surface [abore the Styloid process)MUSCLES (2) ORIGIN - FROM POSTERIOR SURPACE(i) ABDUCTOR Powers LONGUS - From middle 1/3 of post surface.(Below posterior oblique line)(ii) EXTENSOR POLLICIS BREVIS - From lower 1/3 of posterior surface.(Below abductor pollia's longus) THE RADIUS4CLINICAL ANATOMYThe radius is a weight bearing bone of forearm, hence fracturesof radius are more common the ulna.Colles Fracture :- Radius commonly gets fractured about 2cmabove its lower end. This fracture is causedby a fall on the outstretched hand.The distal fragment is displaced upwards and backwardsand the radial Styloid process comes to lie proximal to theulnar Styloid process.DIPANKAR RAYSmith's Fracture :- If the distal fragment gets displaced anteriorlyit is called Smith's Fracture.Chauffeur's Fracture :- Fracture of Styloid process of radiusis termed Chauffeur's fracture.SUBLIXATION OF HEAD OF RADIUS :- A sudden powerful jerk on thePULLED ELBOWthe head of the radius from grip of annular ligament. This ishand of a child may dislodgeknown as subluxation of the head of radius (Pulled elbow) STRUCTUREATTACHMENT TO RADIUSATTACHMENT TO ULNAattached to the neck of RadiusSurrounds the head and losselyAttached to the anterior & posteriorburders of radial notchSIts lateral end is attached toIts medial end is attached justthe medial side of meck of Radius.below the radial notch.EFFECTIVEAttached just below theAttached to the lateral side of theObugue CORD.radial tuberosity.ulnar tuberosity below quadrateligament.Attached to Interosseous borderAncired to Interosscout borderof radius.of innaCARTLE RADIO ULVAR/Attached around the articular surfaces ofLower end of radius & ulnaDepartmentIts base-attached to InferiorIts apex - attached to depressionRADIO-OLYborder of the ulnar hotchat base of the Styloid process.of radius.