Osteology of the Upper Limbs Ana 201 PDF

Osteology of the Upper Limbs Ana 201 Dr Olabanji  Upper limbs The Upper limbs can be divided into 4 segments – Pectoral girdle ( scapula & clavicle) Arm (humerus) Fore arm (radius & ulna) Hand (carpals, metacarpals, phalanges) ...

Osteology of the Upper Limbs Ana 201 Dr Olabanji  Upper limbs The Upper limbs can be divided into 4 segments – Pectoral girdle ( scapula & clavicle) Arm (humerus) Fore arm (radius & ulna) Hand (carpals, metacarpals, phalanges)  Scapula is also called shoulder blade. Is a triangular flat bone that lies on the posterolateral aspect of the thorax, overlying the 2nd -7th ribs. It has a body (shaft) Lateral surface The convex posterior surface A concave costal surface Borders:  The body: Is triangular, thin and translucent superior and inferior to the scapular spine. The lateral surface: is the surface that faces the humerus. It has a fossa called the glenoid fossa, which is the site of the glenohumeral joint. Has two tubercle, supraglenoid and infraglenoid tubercles. This tubercles form an attachment for muscles. The long head of biceps brachii is attached to supraglenoid tubercle The long head of triceps brachii is attached to the infraglenoid tubercle. The convex surface: is unevenly divided by a thick projecting ridge of bone, the spine of the scapula, into a small supraspinous fossa and a much larger infraspinous fossa.  The spine continues laterally as the flat expanded acromion, which articulates with the acromial end of the clavicle The concave costal surface: is a large concave depression on the surface of the scapula and forms a large subscapular fossa (form an attachment for subscapularis muscle) Aside this fossa, is the coracoid process, a hooklike projection anterolaterally. Superior to the glenoid cavity. Three muscles are attached to this process.  The superior border is marked near the junction of its medial two thirds and lateral third by the suprascapular notch, which is located where the superior border joins the base of the coracoid process. The thin medial border of the scapula runs parallel to and approximately 5 cm lateral to the spinous processes of the thoracic vertebrae. the lateral border of the scapula runs superolaterally toward the apex of the axilla  Applied Anatomy Fracture of the Scapula Fracture of the scapula is usually the result of severe trauma, As occurs in pedestrian vehicle accidents. Most fractures require little treatment because the scapula is covered on both sides by muscles. Most fractures involve the protruding subcutaneous acromion.  Clavicle Also called collar bone Is a long slightly curved bone forming like a s shape. Connects the upper limb to the trunk. It helps keep the shoulder blade in position. It extends between the manubrium of the sternum and acromium of the scapula. It has a sternal end, a shaft and an acromial end  The shaft: its medial two thirds are convex anteriorly, whereas the lateral third is flattened and concave anteriorly. These curvatures increase the resilience of the clavicle and give it the appearance of an elongated capital S. On the medial third of the shaft of the clavicle is a groove, The subclavian groove (groove for the subclavius) is the site of attachment of the subclavius muscle The sternal end: is enlarged and triangular where it articulates with the manubrium of the sternum at the sternoclavicular joint.  The acromial end: is flat where it articulates with the acromion of the scapula at the acromioclavicular joint. It serves as an attachment for ligaments The conoid tubercle, near the acromial end of the clavicle gives attachment to the conoid ligament. This is the medial part of the coracoclavicular ligament. Near the acromial end of the clavicle is the trapezoid line, the trapezoid ligament attaches to this line; it is the lateral part of the coracoclavicular ligament, Is the ligaments that helps to suspend the weight of the upper limb from the clavicle.  Applied Anatomy Fracture of the Clavicle The clavicle is one of the most frequently fractured bones. Its common in children. Are often caused by an indirect force transmitted from an outstretched hand through the bones of the forearm and arm to the shoulder during a fall. Or could result from a fall directly on the shoulder. The commonest site(weakest part of the clavicle) is the junction of its middle and lateral thirds.  Humerus Is the largest bone in the upper limb. It articulate with the glenoid cavity of the scapula at the glenohumeral joint and with the radius and ulna at the elbow joint. It has a proximal end, shaft (body) and distal end.  The proximal end of the humerus has a head, a neck and greater and lesser tubercules. The head is shaped like a ball, it articulate with the glenoid cavity of scapula. Neck: is the narrow part distal to the head and tubercles. Is the commonest site for fracture of the humerus. The anatomical neck of the humerus is formed by a groove, inter tubercular groove, which separates greater and lesser tubercle (tuberocities). The greater tubercle is at the lateral margin of the humerus while the lesser tubercle project anteriorly.  The shaft (body) of the humerus has two prominent features: The deltoid tuberosity laterally, for attachment of the deltoid muscle, and The oblique radial groove posteriorly, in which the radial nerve and deep artery of the arm lie. The inferior end of the humeral shaft widens as the sharp medial and lateral supraepicondylar (supracondylar) ridges form and then end distally in the especially prominent medial epicondyle and the lateral epicondyle  The distal end of the humerus: includes the trochlea; the capitulum; and the olecranon, coronoid, and radial fossae, Which makes up the condyle of the humerus. The condyle has two articular surfaces: a lateral capitulum head, for articulation with the head of the radius and a medial, spool-shaped or pulley-like trochlea for articulation with the proximal end (trochlear notch) of the ulna.  Superior to the trochlear are two hollow or fossa. Anteriorly, the coronoid fossa receives the coronoid process of the ulna during full flexion of the elbow. Posteriorly, the olecranon fossa accommodates the olecranon of the ulna during full extension of the elbow. Superior to the capitulum anteriorly, is a shallower radial fossa Which accommodates the edge of the head of the radius when the forearm is fully flexed.  Applied Anatomy Fracture of the humerus The most common sites of humeral fracture are surgical neck, shaft and supracondylar regions. The following part of the humerus are in direct contact with the structure indicated below. At the surgical neck – axillary nerve, anterior and posterior circumflex humeral artery. Radial groove – radial nerve, profunda brachial artery Distal end of humerus – median nerve Medial epicondyle – ulnar nerve These nerves and vessel may be injured when the associated part of the humerus is fractured.  Bones of the forearm Ulna is the medial and longer of the two forearm bones It articulate with the trochlea of the humerus at the elbow joint and with the radius at the proximal and distal radioulna joint. It has a proximal end, shaft (body) and distal end  The proximal end For articulation with the humerus, it has two prominent projections: The olecranon, which projects proximally from its posterior aspect. The coronoid process, which projects anteriorly. Both of them forms the wall of the trochlear notch. Inferior to the coronoid process is the tuberosity of the ulna for attachment of the tendon of the brachialis muscle. On the lateral side of the coronoid process is a smooth, rounded concavity, the radial notch, which receives the broad periphery of the head of the radius.  The body (shaft) is thick and cylindrical proximally, but it tapers, diminishing in diameter as it continues distally. At its narrow distal end is a somewhat abrupt enlargement forming a disc like head and a small conical styloid process.  Radius is the lateral and shorter of the two forearm bones. Its proximal end includes a short head, neck, and medially directed tuberosity. Proximally, the smooth superior aspect of the discoid head of the radius is concave for articulation with the capitulum of the humerus  The neck of the radius is a constriction distal to the head. The oval radial tuberosity is distal to the medial part of the neck and demarcates the proximal end (head and neck) of the radius from the shaft. The shaft (body) of the radius, in contrast to that of the ulna, gradually enlarges as it passes distally. The distal end of the radius: Its medial aspect forms a concavity, the ulnar notch, which accommodates the head of the ulna. Its lateral aspect becomes increasingly ridge-like, terminating distally in the radial styloid process.  Bones of the hand The wrist, or carpus, is composed of eight carpal bones (carpals) arranged in proximal and distal rows of four. These small bones give flexibility to the wrist. The carpus is markedly convex from side to side posteriorly and concave anteriorly From lateral to medial, the 4 bones in the proximal row of carpals are scaphoid (boat shaped), Lunate (moon shaped), triquetrum (pyramidal bone) and pisiform (pea shaped bone lying on the palmer surface of triquetrium). From the lateral to medial, the four bones in the distal row of carpal are trapezium, trapezoid, capitate and hamate. The hamate has a hook-like process called hook of hamate.  Metacarpals and phalanges The metacarpus forms the skeleton of the palm of the hand between the carpus and the phalanges. It is composed of five (metacarpus). Each metacarpal consist of a body and two ends. The proximal bases of the metacarpals articulate with the carpal bones, and the distal heads of the metacarpals articulate with the proximal phalanges and form the knuckles. The 1st metacarpal (of the thumb) is the thickest and shortest of these bones. The 3rd metacarpal is distinguished by a styloid process on the lateral side of its base Each digit has 3 phalanges except the first digit (thumb) which has only 2. The phalanges of the first digit are stouter than those in the other fingers. Each phalanx has a base proximally, a shaft (body), and a head distally  Thank you