The upper limb 3/19/2021 1 Introduction The upper limb ▪Is the organ of the body, responsible for manual activities. ▪It is freely movable, especially its distal segment - the hand, which is adapted for grasping and manipulating the objects. ▪The upper limbs are connected to the trunk by a pectoral girdle. 3/19/2021 3 Relationship to other regions Neck ▪The major nerves, arteries and veins of the upper limb pass between the thorax and the limb by passing over rib I and through the axillary inlet. Back and thoracic wall ▪Muscles that attach the bones of the shoulder to the trunk are associated with the back and the thoracic wall. 3/19/2021 4 3/19/2021 5 Parts of the upper limb ▪For descriptive purposes, the upper limb is divided into: The shoulder region Axilla or armpit, Scapular region Pectoral or breast region The arm The part between shoulder and elbow (or cubitus). 3/19/2021 6 The forearm The part between the elbow and the wrist. The hand (or manus) Consists of: −Wrist or carpus, −Hand proper (or metacarpus), and −Digits (thumb and fingers) 3/19/2021 7 3/19/2021 8 Parts of the upper limb Part Subdivisions Bones Joints ▪ Pectoral region ▪Clavicle Shoulde ▪ Axilla r region ▪Scapula ▪ Scapular región ▪Sternoclavicular ▪Acromioclavicular Arm ▪Humerus ▪Shoulder ▪Radius ▪Ulna ▪Elbow ▪Radio-ulnar ▪Carpal ▪Metacarpal ▪Phalanges ▪Wrist/radio-carpal ▪Intercarpal ▪Carpometacarpal ▪Intermetacarpal ▪Metacarpophalangeal ▪Proximal and distal interphalangeal 9 — Forearm — Hand ▪Wrist (carpus) ▪Hand proper (metacarpus) ▪Digits Comparison between the upper and lower limbs Homologous parts of the upper and lower limbs Upper limb ▪Shoulder/pectoral girdle ▪Shoulder joint Lower limb ▪Hip girdle/pelvic girdle ▪Hip joint ▪Arm ▪Thigh ▪Elbow joint ▪Forearm ▪Knee joint ▪Leg ▪Wrist joint ▪Hand (A) Carpus (B) Metacarpus (C) Fingers ▪Ankle joint ▪Foot (A) Tarsus (B) Metatarsus (C) Toes Development of the limbs. 3/19/2021 11 Differences between the upper and lower limbs Upper limb Lower limb Function ▪Prehension (i.e., manipulation of objects by grasping) ▪Locomotion and transmission of weight Bones ▪Smaller and weaker ▪Larger and stronger Joints ▪Smaller and less stable ▪Larger and more stable Muscles ▪Smaller and attached to smaller bony areas. ▪Antigravity muscles less developed ▪Larger and attached to larger bony areas ▪Antigravity muscles more developed Girdle ▪Pectoral girdle (a) Made up of two bones, clavicle and scapula (b) No articulation with vertebral column (c) Articulation with axial skeleton is very small through SC joint ▪Pelvic girdle (a) Made up of single bone, the hip bone (b) Articulates with vertebral column (c) Articulation with axial skeleton is large, through sacroiliac joint Preaxial border ▪Faces laterally ▪Faces medially 3/19/2021 12 Bones of the upper limb ▪Each upper limb consists of 32 bones: Scapula, shoulder blade (1) Clavicle, collar bone (1) Humerus, bone of arm (1) Radius and ulna, bones of forearm (2) Carpal bones, bones of wrist (8) Metacarpals, bones of hand (5) Phalanges, bones of digits (fingers) (14) The Clavicle (collar bone) ▪A long, slender bone that lies horizontally across the root of the neck just beneath the skin. ▪Is the only long bone without a medullary cavity. Consists of spongy (trabeculae) bone with a shell of compact bone. ▪It is subcutaneous throughout its extent. ▪The clavicle ossifies in a membrane and it is the first bone to start ossification at around the 5th week of development. 3/19/2021 Dawit H. 16 ▪It articulates with the sternum and first costal cartilage medially and with the acromion process of the scapula laterally. ▪The medial two thirds of the clavicle is convex anteriorly and its lateral third is concave anteriorly. 3/19/2021 Dawit H. 17 Parts of clavicle Sternal end ▪Enlarged and triangular where it articulates with the manubrium of the sternum at the sternoclavicular (SC) joint. Acromial end ▪Is flat where it articulates with the acromion of the scapula at the acromioclavicular (AC) joint. ▪Nearer to the acromial end on the anterior border of the clavicle there is a small thickening called deltoid tubercle. 3/19/2021 Dawit H. 18 3/19/2021 Dawit H. 19 The superior surface: ▪Smoother than the inferior surface. The inferior surface: ▪Rough Strong ligaments bind it to the 1st rib near its sternal end and suspend the scapula from its acromial end. ▪The lateral 1/3 possesses: ▪The conoid tubercle Gives attachment to the conoid ligament (medial part of the coracoclavicular lig.). 3/19/2021 20 ▪Trapezoid line For attachment of the trapezoid ligament (the lateral part of coracoclavicular ligament). ▪In the meddle third of the shaft of the clavicle : ▪The subclavian groove Site of attachment of the subclavius muscle. ▪More medially is the impression for the costoclavicular ligament, that gives attachment to the ligament binding the 1st rib to the clavicle, limiting elevation of the shoulder. 3/19/2021 Dawit H. 21 Right clavicle showing attachments of the muscles and ligaments: A, superior surface; B, inferior surface. ▪Forces of the upper limb are transmitted to the axial skeleton by clavicle through costoclavicular ligament and sternoclavicular joint. Transmission of force in the upper limb. Clinical correlations ▪The fracture at the junction of lateral one-third and medial two-third occurs because: This is the weakest site. Two curvatures of clavicle meet at this site. The transmission of forces (due to impact) from the clavicle to scapula occur at this site through coracoclavicular ligament. Clavicle fracture: A, medial fragment; B, lateral fragment. The Scapula ▪Is a large triangular bone in the dorso-lateral aspect of the thorax at the level of the 2nd - 7th ribs. ▪Articulates with the humerus and the clavicle. ▪The scapula has body and three processes: ▪The body is triangular, thin, and transparent. ▪It presents: Two surfaces: costal and dorsal. Three borders: superior, lateral, and medial. Three angles: inferior, superior, and lateral. 25 B. Posterior aspect ▪The dorsal surface presents a shelf-like projection on its upper part called spinous process. ▪The superolateral angle of the scapula forms the glenoid cavity, or fossa. Glenoid cavity is enlarged by a glenoidal labrum (fibrocartilaginous rim) to accommodate the large head of the humerus. ✓Above and below the glenoid cavity there are supraglenoid and infraglenoid tubercles that provide attachment sites for the long heads of biceps and triceps muscles respectively. 3/19/2021 Dawit H. 27 Scapula Lateral view The lateral angle is thickened and called head of the scapula, which is connected to the plate-like body by an inconspicuous neck. ▪There are three processes ✓Coracoid process: projects above the glenoid cavity and provides attachment for muscles and ligaments. Medial to the base of the coracoid process is the suprascapular (scapular) notch. ▪Bridged over by the suprascapular (superior transverse scapular) ligament forming a foramen that transmits the suprascapular nerve to the supraspinous fossa, while the suprascapular vessels ride over the ligament. 3/19/2021 ▪The inferior belly of omohyoid arises from this ligament.Dawit H. 29 ✓Spinous process: is a shelf-like bony projection on the dorsal aspect of the body. ✓Acromion process: projects forwards almost at right angle from the lateral end of the spine. ▪The dorsal surface of the scapula is divided by the spine into the supraspinous fossa above and an infraspinous fossa below. The two fossae communicate laterally via the spinoglenoidal notch. 3/19/2021 Dawit H. 31 ▪The anterior surface (costal surface) of the scapula: Is concave and forms the shallow subscapular fossa. Together with its related muscle (subscapularis), move freely over the underlying thoracic wall. ▪The lateral border of the scapula is strong and thick for muscle attachment, whereas the medial border and much of the superior border is thin and sharp. 3/19/2021 Dawit H. 32 A. Anterior aspect The humerus Upper end (proximal end) Head Directed medially, backwards and upwards Articulates with the glenoid cavity to form shoulder joint. Covered by a hyaline cartilage. Neck Anatomical: ▪Formed by the groove circumscribing the head and separating it from the greater and lesser tubercles. 36 It indicates the line of attachment of the glenohumeral joint capsule. Surgical neck: ▪A short constriction in the upper end of the shaft below the greater and lesser tubercles/ below the epiphyseal line. It is related to axillary nerve and posterior and anterior circumflex humeral vessels. Lesser tubercle: ▪Is an elevation on the anterior aspect of the upper end just above the surgical neck. Provides attachment to subscapularis muscle. Right humerus: A, anterior view; B, posterior view. Greater tubercle: ▪An elevation that forms the lateral part of the upper end. ▪Its superior surface and posterior surface are marked by three large smooth facets for muscle tendon attachment: (supraspinatus, infraspinatus, and teres minor muscles, respectively) SIT 3/19/2021 Dawit H. 39 Right humerus showing attachments of the muscles and ligaments: A, anterior aspect; B, posterior aspect. Intertubercular sulcus (Bicipital groove) It is a vertical groove between lesser and greater tubercles. Contains long head of biceps, enclosed in the synovial sheath and ascending branch of anterior circumflex humeral artery. Roughenings on the lateral and medial lips and on the floor of the intertubercular sulcus mark sites for the attachment of the pectoralis major, teres major, and latissimus dorsi muscles, respectively. 3/19/2021 Dawit H. 41 Shaft ▪Is rounded in the upper half and triangular in the lower half. ▪Has three borders and three surfaces: Borders: Anterior, Lateral, and Medial. Surfaces: Anterolateral, Anteromedial, and Posterior. ▪The posterior surface of the humerus is marked on its superior aspect by a linear roughening for the attachment of the lateral head of the triceps brachii muscle. 3/19/2021 Dawit H. 42 3/19/2021 Dawit H. 43 ▪Has Deltoid tuberosity: laterally, for attachment of the deltoid muscle. Behind and below the tuberosity is radial sulcus (radial groove, radial fossa or spiral groove through which the radial nerve pass. ▪Approximately in the middle of the shaft, the medial border is marked by thin elongate roughening for the attachment of the coracobrachialis muscle. 3/19/2021 Dawit H. 44 3/19/2021 Dawit H. 45 ▪Intermuscular septa, which separate the anterior compartment from the posterior compartment, attach to the medial and lateral borders of the shaft of the humerus. 3/19/2021 Dawit H. 46 ▪Distally, the bone becomes flattened, and these borders expand as the lateral supraepicondylar ridge (lateral supracondylar ridge) and the medial supraepicondylar ridge (medial supracondylar ridge). The lateral supraepicondylar ridge is more pronounced than the medial and is roughened for the attachment of muscles found in the posterior compartment of the forearm. 3/19/2021 Dawit H. 47 Lower End ▪Has condyles, epicondyles, and fossae: The Condyle ▪Has two articular parts, the capitulum and the trochlea, articulate with the two bones of the forearm. The capitulum ▪Articulates with the radius of the forearm. ▪Not visible when the humerus is viewed from the posterior aspect. 3/19/2021 Dawit H. 48 The trochlea ▪Medial to the capitulum. ▪Articulates with the ulna of the forearm. ▪Its medial edge is more pronounced than its lateral edge and, unlike the capitulum, it extends onto the posterior surface of the bone. 3/19/2021 Dawit H. 49 The two epicondyles The medial epicondyle A large bony protuberance, projects medially from the distal end of the humerus. On its surface, it bears a large oval impression for the attachment of muscles in the anterior compartment of the forearm. The ulnar nerve passes from the arm into the forearm around the posterior surface of the medial epicondyle. 3/19/2021 Dawit H. 50 The lateral epicondyle Is much less pronounced than the medial epicondyle. It is lateral to the capitulum and has a large irregular impression for the attachment of muscles in the posterior compartment of the forearm. 3/19/2021 Dawit H. 51 The three fossae ▪Accommodate projections from the bones in the forearm during movements of the elbow joint. ▪The radial fossa: Immediately superior to the capitulum on the anterior surface of the humerus. Accommodates the edge of the head of the radius when the forearm is fully flexed. ▪The coronoid fossa: Adjacent to the radial fossa and is superior to the trochlea. 3/19/2021 Dawit H. 53 Receives the coronoid process of the ulna during full flexion of the elbow ▪The olecranon fossa: ▪Immediately superior to the trochlea on the posterior surface of the distal end of the humerus. ▪Accommodates the olecranon process of the ulna during full extension of the elbow. 3/19/2021 Dawit H. 54 3/19/2021 Dawit H. 55 Clinical correlates The three nerves related to the back of the humerus. These nerves are involved in the fracture of the humerus at these sites. ▪Common sites of fractures of the humerus: Surgical neck. Shaft. Supracondylar region. The Forearm The Radius ▪Lateral bone of the forearm & is homologous with the tibia of lower limb. ▪Thinner proximally & progressively thickens distally. ▪Consists of three parts: upper end, shaft, and lower end. Proximal end •Consists of the head, neck & radial tuberosity. 3/19/2021 Dawit H. 58 Right radius and ulna: A, Anterior view; B, Posterior view The Head Disc shaped & is covered with hyaline cartilage. Has superior concave surface which articulates with capitulum of humerus at the elbow joint. Has articular circumference that rotates in the radial notch of the ulna, covered by hyaline cartilage & surrounded by annular ligament. The Neck Is a short and narrow cylinder of bone between the expanded head and the radial tuberosity on the shaft. The radial tuberosity A large blunt projection on the medial surface of the radius immediately inferior to the neck. Much of its surface is roughened for the attachment of the biceps brachii tendon. The oblique line of the radius continues diagonally across the shaft of the bone from the inferior margin of the radial tuberosity. 3/19/2021 Dawit H. 61 3/19/2021 Dawit H. 62 The shaft ▪Is triangular in cross-section, with: Three borders (anterior, posterior, and interosseous). Three surfaces (anterior, posterior, and lateral). 3/19/2021 Dawit H. 63 The anterior border ▪Begins 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. 64 3/19/2021 Dawit H. 65 The posterior surface ▪Is characterized by the presence of a large dorsal tubercle, which acts as a pulley for the tendon of one of the extensor muscles of the thumb (extensor pollicis longus). The medial surface ▪Is marked by a prominent facet for articulation with the distal end of the ulna. The lateral surface ▪Is diamond shaped and extends distally as a styloid process. 3/19/2021 Dawit H. 66 3/19/2021 Dawit H. 67 ▪The distal end of the bone is marked by two facets for articulation with two carpal bones (the scaphoid and lunate). The Ulna ▪Is the medial and longer bone of the forearm and is homologous to fibula of lower limb. ▪Its thickness decreases in a distal direction. Proximal/Upper End. ▪Presents the olecranon, coronoid process, the trochlear and radial notches and the tuberosity of ulna. 3/19/2021 68 The olecranon A large projection of bone that extends proximally from the ulna. Its anterolateral part contributes to the formation of the trochlear notch, which articulates with the trochlea of the humerus. The superior surface is marked by a large roughened impression for the attachment of the triceps brachii muscle. 3/19/2021 Dawit H. 69 3/19/2021 Is the attachment site for the brachialis muscle. 70 The coronoid process Projects anteriorly from the proximal end of the ulna. Its superolateral surface is articular and participates, with the olecranon, in forming the trochlear notch. The lateral surface is marked by the radial notch for articulation with the head of the radius. 3/19/2021 Dawit H. 71 The shaft of the ulna Tapers from above down. It has a sharp interosseous border laterally for the attachment of the interosseous membrane. The posterior border is rounded and subcutaneous and can be easily palpated throughout its length. Below the radial notch is the supinator crest that gives origin to the supinator muscle. 72 The distal end ▪It presents a convex articular surface on its lateral side for articulation with the ulnar notch of radius to form the inferior radio-ulnar joint. ▪ Its inferior surface is smooth and separated from wrist joint by an articular disc of inferior radio-ulnar joint. ▪Has projecting from its medial aspect the styloid process. 3/19/2021 Dawit H. 74 3/19/2021 Dawit H. 75 Bones of the Hand ▪Three groups of bones in the hand: The eight carpal bones are the bones of the wrist. The five metacarpals (I to V) are the bones of the metacarpus. The phalanges are the bones of the digits-the thumb has only two, the rest of the digits have three. 3/19/2021 Dawit H. 76 3/19/2021 Dawit H. 77 Carpal Bones (G. Corpus = wrist) ▪Arranged in two rows. 1. Proximal row contains (from lateral to medial) Scaphoid Lunate Triquetral Pisiform 2. Distal row contains in the same order Trapezium Trapezoid Capitate Hamate 78 Carpal bone Identifying features ▪Boat-shaped 1. Scaphoid ▪Has constriction (neck) ▪Has tubercle on distal part of its palmar surface 2. Lunate ▪Moon-shaped/crescentic ▪Pyramidal in shape 3.Triquetral ▪Oval facet on the distal part of its palmar surface for articulation with pisiform ▪Pea-shaped/pea-like 4. Pisiform ▪Oval facet on the proximal part of its dorsal surface ▪Quadrilateral in shape 5.Trapezium ▪Has groove and crest (tubercle) on its palmar surface 6. Trapezoid ▪Shoe-shaped ▪Largest carpal bone 7. Capitate ▪Has rounded head on its proximal surface ▪Wedge-shaped 8. Hamate ▪Hook-like process projects from distal part of its palmar surface ▪The carpal bones do not lie in a flat coronal plane; rather, they form an arch, whose base is directed anteriorly. The lateral side of this base is formed by the tubercles of the scaphoid and trapezium. The medial side is formed by the pisiform and the hook of hamate. ▪The flexor retinaculum attaches to, and spans the distance between, the medial and lateral sides of the base to form the anterior wall of the so-called carpal tunnel. 3/19/2021 Dawit H. 80 Palmar aspect of the carpal and metacarpal bones of the left hand 3/19/2021 Dawit H. 81 Dorsal aspect of the carpal and metacarpal bones of the left hand. 3/19/2021 Dawit H. 82 The sides and roof of the carpal tunnel are formed by the arch of the carpal bones. Metacarpals ▪These are 5 miniature long bones, which are numbered from lateral to medial side. Metacarpal I is related to the thumb. Metacarpals II to V are related to the index, middle, ring, and little fingers, respectively. Each bone has a head (placed distally), a shaft and a base (at the proximal end). 3/19/2021 Dawit H. 83 3/19/2021 Dawit H. 84 Phalanges ▪There are 14 phalanges in each hand, 3 for each finger and 2 for the thumb. ▪Each phalanx has a base, a shaft and a head. ▪The base of each proximal phalanx articulates with the head of the related metacarpal bone. 3/19/2021 Dawit H. 85
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