Bones of the Upper Extremity PDF

UPPER LIMBS DR R. ROBERTS-MARTIN Upper Limb Divided into four(4) parts based on the position of its major joints and component bones: Hand Forearm Arm Shoulder, which is the region of upper limb attachment to the trunk Upper Limb Shoulder Complex = Shoulder girdle (scapula and clavicle)...

UPPER LIMBS DR R. ROBERTS-MARTIN Upper Limb Divided into four(4) parts based on the position of its major joints and component bones: Hand Forearm Arm Shoulder, which is the region of upper limb attachment to the trunk Upper Limb Shoulder Complex = Shoulder girdle (scapula and clavicle) and Shoulder joint (scapula and humerus) Shoulder Girdle The scapula and clavicle. The sternoclavicular (SC) and acromioclavicular (AC) joints allow shoulder girdle motions ◦ Elevation and depression ◦ Protraction and retraction ◦ Upward and downward rotation  Bones of the Shoulder The shoulder consists of three (3) bones:  Clavicle Scapula (shoulder blade) Proximal end of the humerus Scapula The scapula is a large, flat triangular bone with: three angles (lateral, superior, and inferior) three borders (superior, lateral, and medial) two surfaces (costal and posterior) three processes (acromion, spine, and coracoid process) The supraglenoid tubercle is located superior to the glenoid cavity and is the site of attachment for the long head of the biceps brachii muscle. The lateral angle of the scapula is marked by the glenoid cavity, which articulates with the head of the humerus to form the glenohumeral joint. The infraglenoid tubercle inferior to the glenoid cavity is the site of attachment for the long head of the triceps brachii muscle. The acromion, which is an anterolateral projection of the spine, arches over the glenohumeral joint and articulates, via a small oval facet on its distal end, with the clavicle. A prominent spine subdivides the posterior surface of the scapula into a small, superior supraspinous fossa and a much larger, inferior infraspinous fossa. Greater scapular notch , suprascapular notch Clavicle Has a ‘S’ shaped contour. Medial end articulates with the sternum and first costal cartilage. Lateral end articulates with the scapula – (at the tip of the acromion; acromial facet). The inferior surface of the lateral third of the clavicle possesses a distinct tuberosity consisting of a tubercle (the conoid tubercle) and lateral roughening (the trapezoid line), for attachment of the coracoclavicular ligament. Clavicle Joints Sternoclavicular Acromioclavicular Glenohumeral (shoulder joint) The sternoclavicular and acromioclavicular link the bones of the pectoral girdle to each other and to the trunk. The glenohumeral joint is the articulation between the humerus of the arm and the scapula. Sternoclavicular Joint Synovial, saddle-shaped joint. Occurs between the proximal end of the clavicle and the clavicular notch of the manubrium sternum together with a small part of the first costal cartilage. The articular cavity is completely separated into two compartments by an articular disc. Predominantly allows movement of the clavicle in the anteroposterior and vertical planes, though some rotation occurs. Sternoclavicular Joint Anterior sternoclavicular ligament – attaches from the anterior surface of the medial end of the clavicle and moves inferomedially onto the anterior surface of the manubrium of the sternum and first costal cartilage. Posterior sternoclavicular ligament – a weaker band posterior to the joint. It descends inferomedially from the back of the sternal end of the clavicle to the back of the upper manubrium. Interclavicular ligament – links the ends of the two clavicles to each other and to the superior surface of the manubrium of the sternum. Costaclavicular ligament - positioned laterally to the joint and links the proximal end of the clavicle to the first rib and related costal cartilage. Acromioclavicular Joint Small synovial joint between oval facet on the medial surface of the acromion and a similar facet on the acromial end of the clavicle. Allows movement in the anteroposterior and vertical planes together with some axial rotation. Reinforced by two ligaments: Acromioclavicular ligament – superior to the joint and passing between adjacent regions of the clavicle and acromion; small. Acromioclavicular Joint Acromioclavicular Joint cont’d Coracoclavicular ligament – not directly related but an important accessory ligament, providing much of the weightbearing support for the upper limb on the clavicle and maintaining the position of the clavicle on the acromion. Comprised of an anterior trapezoid ligament (which attaches to the trapezoid line on the clavicle) and a posterior conoid ligament (which attaches to the related conoid tubercle). Glenohumeral Joint The glenohumeral joint is a synovial ball and socket articulation between the head of the humerus and the glenoid cavity of the scapula. Multiaxial. Joint stability is provided, by the rotator cuff muscles, the long head of the biceps brachii muscle, related bony processes, and extracapsular ligaments. Articular surfaces  Glenohumeral Joint cont’d Movements at the joint include flexion, extension, abduction, adduction, medial rotation, lateral rotation, and circumduction. The fibrous membrane of the joint capsule is thickened: anterosuperiorly in three locations to form superior, middle, and inferior glenohumeral ligaments, which pass between the superomedial margin of the glenoid cavity to the lesser tubercle and inferiorly related anatomical neck of the humerus Glenohumeral Joint Glenohumeral Joint cont’d superiorly between the base of the coracoid process and the greater tubercle of the humerus (the coracohumeral ligament) between the greater and lesser tubercles of the humerus (transverse humeral ligament)-this holds the tendon of the long head of the biceps brachii muscle in the intertubercular sulcus. ARM The region of the upper limb between the shoulder and the elbow. Divided into two compartments by medial and lateral intermuscular septa. Bone of arm is the humerus. Proximal Humerus The proximal end of the humerus consists of the head, the anatomical neck, the greater and lesser tubercles, the surgical neck, and the superior half of the shaft of humerus. The greater and lesser tubercles are prominent landmarks that serve as attachment sites for the four rotator cuff muscles of the glenohumeral joint. The greater tubercle is lateral in position.  Proximal Humerus Cont’d The superior and posterior surface of the greater tubercle are marked by three large smooth facets for muscle tendon attachment of the rotator cuff muscles. From the superior facet to inferior facet they are: the supraspinatus muscle, infraspinatus and teres minor. The lesser tubercle is anterior in position and its surface is marked by a large smooth impression for attachment of the subscapularis muscle. Proximal Humerus Proximal Humerus Cont’d A deep intertubercular sulcus (bicipital groove) separates the lesser and greater tubercles and continues inferiorly onto the proximal shaft of the humerus. The tendon of the long head of the biceps brachii passes through this sulcus. One of the most important features of the proximal end of the humerus is the surgical neck. Proximal Humerus Cont’d The surgical neck is weaker than more proximal regions of the bone and 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. Deltoid tuberosity Shaft and Distal End of Humerus In cross-section, the shaft of the humerus is somewhat triangular with: anterior, lateral, and medial borders; anterolateral, anteromedial, and posterior surfaces Shaft and Distal End of Humerus Shaft and Distal End of Humerus Distal end has a condyle, 2 epicondyles and 3 fossae. Condyle has 2 articular parts; capitulum (for radius)(not visible from posterior), trochlea (for ulna). Medial epicondyle – bears large oval impression for attachment of anterior compartment muscles. Shaft and Distal End of Humerus  Shaft and Distal End of Humerus cont’d Lateral epicondyle (less pronounced) – large irregular impression for attachment of posterior compartment muscles. Radial, coronoid, olecranon fossae – accomodate projections of forearm bones during elbow movement.  Elbow The joints between the trochlear notch of the ulna and the trochlea of the humerus and between the head of the radius and the capitulum of the humerus are primarily The elbow joint is a complex involved with hinge-like flexion and joint involving three separate extension of the forearm on the arm and, articulations, which share a together, are the principal articulations of the common synovial cavity. elbow joint. Elbow Cont’d The joint between the head of the radius and the radial notch of the ulna, the proximal radio-ulnar joint, is involved with pronation and supination of the forearm. Elbow Ligaments The radial collateral ligament extends laterally from the epicondyle of the humerus and blends distally with the anular ligament of the radius, which wraps around the head of the radius and holds the radius in the radial notch of the ulna. Ulnar collateral ligament, extends from the medial epicondyle of the humerus to the coronoid process and the olecranon of the ulna. Consists of three bands: The anterior cord like band (strongest) The posterior fanlike band (weakest) Oblique band (deepens the socket for the trochlea of the humerus) FOREARM Forearm The forearm is the part of the upper limb that extends between the elbow joint and the wrist joint. The bones of the forearm consists of the radius and the ulna. The radius is lateral in position and is small proximally, where it articulates with the humerus, and large distally, where it forms the wrist joint with the carpal bones of the hand. RADIUS Lateral and shorter of the two forearm bones. Head of radius is concave for the articulation of the of the capitulum of the humerus, during flexion and extension of the elbow. Also articulates peripherally with radial notch of the ulnar. Ulnar notch accommodates the head of the ulna. Proximal end of radius Head Neck Radial tuberosity – roughened for attachment of biceps brachii. Radius Ulna Stabilising bone of the forearm. Medial and the longer bone of the forearm. Trochlear articulates with the trochlea of the humerus. Ulnar tuberosity, forms the attachment of the tendon for the brachialis muscle. Proximal end of ulna Olecranon – roughening on superior surface for triceps brachii attachment. Coronoid process – participates in forming trochlear notch with olecranon. Trochlear notch – for articulation with trochlea of humerus. Radial notch – for articulation with head of radius. Proximal end of ulna Ulna Interosseous Membrane The interosseous membrane is a thin fibrous sheet that connects the medial and lateral borders of the radius and ulna, respectively. Divides the forearm into anterior and posterior compartments. The circular aperture allows the passage of vessels between the anterior and posterior compartments. Hand The hand is subdivided into: the wrist the metacarpus the digits (five fingers including the thumb). The five digits consist of the laterally positioned thumb and, medial to the thumb, the four fingers- the index, middle, ring, and little fingers Hand cont’d The hand has an anterior surface (palm) and a dorsal surface (dorsum of hand). The carpal bones and metacarpals of the index, middle, ring, and little fingers (metacarpals II to V) tend to function as a unit and form much of the bony framework of the palm. The metacarpal bone of the thumb functions independently and has increased flexibility at the carpometacarpal joint to provide opposition of the thumb to the fingers Bones of the Carpal The small carpal bones of the wrist are arranged in two rows, a proximal and a distal row, each consisting of four bones. The proximal row of bones consists of: the boat-shaped scaphoid; the lunate, which has a 'crescent shape'; the three-sided triquetrum bone; the pea-shaped pisiform Bones of the Carpal The pisiform is a sesamoid bone in the tendon of flexor carpi ulnaris and articulates with the anterior surface of the triquetrum. Carpals Bones of the Carpal Cont’d Distal Row From lateral to medial and when viewed from anteriorly, the distal row of carpal bones consists of: the irregular four-sided trapezium bone; the four-sided trapezoid; the capitate, which has a head; the hamate, which has a hook. Metacarpals Each metacarpal consists of a base, a shaft, and distally, a head. All of the bases of the metacarpals articulate with the carpal bones; in addition, the bases of the metacarpal bones of the fingers articulate with each other.. All of the heads of the metacarpal bones articulate with the proximal phalanges of the digits... Metacarpals Phalanges The phalanges are the bones of the digits ,the thumb has two-a proximal and a distal phalanx; the rest of the digits have three-a proximal, a middle, and a distal phalanx. Each phalanx has a base, a shaft (body), and distally, a head. The base of each proximal phalanx articulates with the head of the related metacarpal bone. Phalanges Joints Wrist joint The wrist joint is a synovial joint between the distal end of the radius and the scaphoid and lunate. Together, the articular surfaces of the carpals form an oval shape with a convex contour, which articulates with the corresponding concave surface of the radius and articular disc. Wrist joint cont’d The wrist joint allows movement around two axes. The hand can be abducted, adducted, flexed, and extended at the wrist joint. Because the radial styloid process extends further distally than does the ulnar styloid process, the hand can be adducted to a greater degree than it can be abducted. Joints of the Hand References Moore KL, Dalley AF, Clinically Oriented Anatomy, Seventh Edition. 2014. Frank H. Netter. Atlas of Human Anatomy 6th, 2014