University Of Northern Philippines Anatomy LC2 PDF

UNIVERSITY OF NORTHERN PHILIPPINES ANATOMY LC2- SKELETAL SYSTEM: UPPER LIMB COLLEGE OF MEDICINE, BATCH 2028 DR. BOLISLIS | 08/12/2024...

UNIVERSITY OF NORTHERN PHILIPPINES ANATOMY LC2- SKELETAL SYSTEM: UPPER LIMB COLLEGE OF MEDICINE, BATCH 2028 DR. BOLISLIS | 08/12/2024 COURSE OUTLINE IMPORTANT BONY LANDMARKS I. BONES OF THE UPPER LIMB Glenoid fossa shallow cavity, located superiorly A. Scapula on the lateral border B. Clavicle articulates with the head of the C. Humerus humerus to form the D. Ulna glenohumeral (shoulder) joint E. Radius Supraglenoid a roughening immediately F. Hand tubercle superior to the glenoid fossa II. JOINTS OF THE UPPER LIMB attachment of the long head of A. Acromioclavicular joint the biceps brachii B. Sternoclavicular joint Infraglenoid a roughening immediately inferior C. Shoulder (Glenohumeral) joint tubercle to the glenoid fossa D. Elbow joint attachment of the long head of E. Radioulnar joint the triceps brachii F. Wrist joint Table 1. Important landmarks of the lateral surface of the scapula G. Metacarpophalangeal joint H. Proximal Interphalangeal joint I. BONES OF THE UPPER LIMB A. THE SCAPULA AKA: Shoulder blade Articulates with the humerus at the glenohumeral joint, and with the clavicle at the acromioclavicular Figure 3. Lateral view of the joint scapula Connects the upper limb to the trunk A triangular, flat bone, which serves as a site for attachment for many muscles. POSTERIOR SURFACE Faces outwards Site of origin for the majority of the rotator cuff muscles (supraspinatus, infraspinatus, teres minor & subscapularis) of the shoulder It is marked by: ○ Spine - most prominent feature; run transversely across the scapula, dividing the surface into two ○ Acromion - projection of the spine that arches over the glenohumeral joint - articulates with the clavicle at the Figure 1. Scapula acromioclavicular joint ○ Infraspinous fossa - area below the spine of COSTAL (ANTERIOR) SURFACE the scapula; displays a convex shape Faces the ribcage - origin of the infraspinatus muscle Subscapular fossa - a large concave depression ○ Supraspinous fossa - area above the spine of over most of its surface the scapula; much smaller than the infraspinous ○ Origin of subscapularis muscle (rotator cuff fossa & more convex in shape muscle) - origin of the supraspinatus muscle Coracoid process - originating from the superolateral surface of the coastal scapula ○ Hook-like projection, which lies underneath the clavicle ○ Attachment of 3 muscles: pectoralis minor coracobrachialis short head of the biceps brachii Figure 4. The posterior surface of the scapula Figure 2. The costal surface of the scapula ARTICULATIONS The scapula has 2 main articulations: Glenohumeral joint - between the glenoid fossa LATERAL SURFACE and head of the humerus Faces the humerus Acromioclavicular joint - between the acromion Site of the glenohumeral joint, and various and clavicle muscle attachments BATCH 2028 1A 1 ANATOMY LC 2: SKELETAL SYSTEM - UPPER LIMB Dr. BOLISLIS, M. 08/12/2024 B. THE CLAVICLE Distally, at the elbow joint, the humerus articulates with the head of the radius and AKA: Collarbone trochlear notch of the ulna. Extends between the manubrium of the sternum & the acromion of the scapula PROXIMAL REGION A long bone that can be palpated along its The proximal humerus is marked by a head, length anatomical neck, surgical neck, greater & lesser tuberosity and intertubercular sulcus. PROXIMAL LANDMARKS Head Upper end of the humerus Faces medially, upwards & backwards Figure 5. The anatomical position of the clavicle. Separated from the greater and lesser tuberosities by the anatomical neck 3 MAIN FUNCTIONS: Greater Located laterally on the humerus and 1. Attaches the upper limb to the trunk as part of tuberosity has anterior & posterior surfaces the 'shoulder girdle' Attachment site for three of the rotator 2. Protects the underlying neurovascular structures cuff muscles: supplying the upper limb ○ Supraspinatus, infraspinatus, & teres 3. Transmits force from the upper limb to the axial minor (attached to the superior, skeleton middle, inferior facets, respectively) Lesser Much smaller, and more medially BONY LANDMARKS AND ARTICULATIONS: tuberosity located The clavicle is a slender bone with an ‘S' shape. Only has an anterior surface Facing forward, the medial aspect is convex, and Attachment of subscapularis (last the lateral aspect concave. rotator cuff muscle) It can be divided into the sternal end, a shaft and an acromial end. Intertubular A deep groove separating the two sulcus tuberosities Sternal Contains a large facet - for Tendon of the long head of the biceps (Medial) articulation with the manubrium of the brachii emerges from the shoulder joint end sternum and runs through this groove The inferior surface is marked by a Lips (edges of the intertubular sulcus) rough oval depression for the ○ Insertion of pectoralis major, teres costoclavicular ligament major and latissimus dorsi Shaft Point of origin and attachment of Surgical Extends from just distal to the several muscles: deltoid, trapezius, neck tuberosities to the shaft of the humerus subclavius, pectoralis major, The axillary nerve and circumflex sternocleidomastoid and sternohyoid humeral vessels lie against the bone Acromial Houses a small facet for articulation here end with the acromion of the scapula Where most of the fractures in the Attachment point of 2 ligaments: proximal humerus occur ○ Conoid tubercle - attachment of the Anatomical Where neuromuscular structure pass conoid ligament (medial part of neck through coracoclavicular ligament) Table 3. Landmarks of the proximal region of the humerus ○ Trapezoid line - attachment of the trapezoid ligament (lateral part of the coracoclavicular ligament) Table 2. Landmarks/Three divisions of the clavicle. Figure 8. The proximal aspect of the humerus. Note the greater and lesser tuberosities as a site of attachment for muscles. Figure 6. Bony landmarks of the inferior surface of the clavicle C. THE HUMERUS SHAFT OF THE HUMERUS Site of attachment for various muscles A long bone of the upper limb, Cross section views: circular proximally and which extends from the flattened distally shoulder to the elbow Deltoid tuberosity - lateral side of humeral shaft; The proximal aspect articulates attachment of deltoid (specifically the middle fibers) with the glenoid fossa of the Radial (or spiral) groove - shallow depression scapula, forming the the runs diagonally down the posterior surface of glenohumeral joint the humerus; parallel to the deltoid tuberosity Figure 7. The anatomical position ○ The radial nerve and profunda brachii artery lie of the humerus in this groove BATCH 2028 1A 2 ANATOMY LC 2: SKELETAL SYSTEM - UPPER LIMB Dr. BOLISLIS, M. 08/12/2024 Muscles attached along the humeral shaft: PROXIMAL OSTEOLOGY & ARTICULATION ○ Anterior - coracobrachialis, deltoid, brachialis, The proximal end of the ulna articulates with the brachioradialis trochlea of the humerus. ○ Posterior - medial and lateral heads of the To enable movement at the elbow joint, the ulna triceps (the spiral groove demarcates their has a specialized structure, with bony respective origins) prominences for muscle attachment. DISTAL REGION IMPORTANT LANDMARKS The lateral and medial borders of the distal Olecranon A large projection of bone that humerus form medial & lateral supraepicondylar extends proximally ridges Palpated as ‘tip’ of the elbow The lateral supraepicondylar ridge is more Triceps brachii muscle attaches to its roughened, providing the site of common origin of superior surface. the forearm extensor muscles Coronoid This ridge of the bone projects Lateral & medial epicondyles process outwards anteriorly ○ Extracapsular projections of bone distal to the Trochlear Formed by the olecranon and supraepicondylar ridges notch coronoid process ○ Medial is larger and extends more distally Wrench shaped, and articulates with ○ The ulnar nerve passes in a groove on the the trochlea of the humerus posterior aspect of the medial epicondyle Radial Lateral surface of the trochlear notch where it is palpable notch Articulates with the head of the radius Trochlea Tuberosity A roughening immediately distal to the ○ located medially, and extends onto the of ulna coronoid process posterior aspect of the bone Attachment of brachialis muscle ○ Capitellum - lateral to the trochlea which Table 4. Important landmarks of the proximal ulna. articulates with the radius THREE DEPRESSIONS: ○ Coronoid, radial and olecranon fossae - accommodate forearm bones during flexion/extension Figure 11. The bony landmarks of the proximal ulna. Figure 9. Bony landmarks of the distal humerus. It articulates with the SHAFT OF THE ULNA radius & ulna to form the elbow joint. Triangular in shape, with three borders and three surfaces. ARTICULATIONS As it moves distally, it decreases in width. Proximal region of the humerus - articulates with the glenoid fossa to form the glenohumeral joint THE THREE SURFACES: (shoulder joint) Anterior - attachment for the pronator quadratus Distally (at the elbow joint) muscle distally ○ Capitulum - articulates with the head of the Posterior - site of attachment for many muscles radius Medial - unremarkable/no anatomic significance ○ Trochlea - articulates with the notch of the ulna THE THREE BORDERS: D. THE ULNA Posterior - palpable along the entire length of the forearm posteriorly A long bone in the forearm Interosseous - site of attachment for the Lies medial and parallel to the radius (second of interosseous membrane, which spans the distance the forearm bones) between the two forearm bones Acts as the stabilizing bone, with the radius Anterior - unremarkable pivoting to produce movement Proximally, articulates with the humerus at the DISTAL OSTEOLOGY AND ARTICULATIONS elbow joint The distal end of the ulna is much smaller in Distally, articulates with the radius, thus forming diameter than the proximal end. the distal radio-ulnar joint Mostly unremarkable, terminating in a rounded head, with distal projection - the ulnar styloid process. The head articulates with the ulnar notch of the radius to form the distal radio-ulnar joint. Figure 10. Overview of the anatomical position of the ulna. BATCH 2028 1A 3 ANATOMY LC 2: SKELETAL SYSTEM - UPPER LIMB Dr. BOLISLIS, M. 08/12/2024 E. THE RADIUS A long bone in the forearm Lies laterally and parallel to ulna Pivots around the ulna to produce movement at the proximal and distal radio-ulnar joints. ARTICULATIONS Elbow joint - between the head of the radius, and the capitulum of the humerus Proximal radioulnar joint (PRUJ) - between the Figure 14. Articular surfaces of the wrist joint. radial head, and the radial notch of the ulna Wrist joint - between the distal end of the radius F. THE HAND and the carpal bones The bones of the hand provide support and flexibility Distal radioulnar joint (DRUJ) - between the to the soft tissues. ulnar notch and the head of the ulna They can be divided into three categories: Carpal bones (proximal) - eight irregularly shaped bones located in the wrist area Figure 12. The anatomical Metacarpals - five metacarpals, each one related structure of the radius. to a digit Phalanges (distal) - bones of the fingers. ○ Each finger has three phalanges, except for the thumb, which has two. PROXIMAL REGION OF THE RADIUS Articulates in both the elbow and proximal radioulnar joints. IMPORTANT BONY LANDMARKS Head of Disk shaped structure, with a concave Radius articulating surface Thicker medially, where it takes part in the proximal radioulnar joint (PRUJ) Neck Narrow area of bone Lies between the radial head & radial Figure 15. Overview of the bones of the hand. tuberosity Radial Bony projection, which serves as CARPAL BONES tuberosity attachment of the biceps brachii A group of eight irregularly shaped bones; muscle organized into two rows: Table 4. Important landmarks of the proximal radius. PROXIMAL ROW DISTAL ROW Scaphoid Trapezium Lunate Trapezoid Triquetrum Capitate Pisiform (a sesamoid Hamate (has a bone, formed within the projection on its palmar tendon of the flexor surface, known as the carpi ulnaris) ‘hook of the hamate’) Table 5. The two rows of the carpal bones. Figure 13. Bony landmarks of the proximal radius. Collectively form an arch in the coronal plane Flexor retinaculum - a membranous band that SHAFT OF THE RADIUS spans between the medial and lateral edge of the Expands in diameter as it moves distally arch, forming the carpal tunnel Much like the ulna, it is triangular in shape, with Proximally, the scaphoid and lunate articulate three borders and three surfaces. with the radius to form the radiocarpal joint (wrist Middle of the lateral surface: has a small joint) roughening for the attachment of the pronator Distally, all of the carpal bones articulate with the teres muscle. metacarpals. DISTAL REGION OF THE RADIUS The radial shaft expands to form a rectangular end The lateral side projects distally as the styloid process Ulnar notch - a concavity in the medial surface ○ Articulates with the head of ulna, forming the distal radioulnar joint (DRUJ) The distal surface of the radius has two facets, for articulation with the scaphoid and lunate carpal bones ○ This makes up the wrist joint. Figure 16. Palmar view of the carpal bones of the left hand. BATCH 2028 1A 4 ANATOMY LC 2: SKELETAL SYSTEM - UPPER LIMB Dr. BOLISLIS, M. 08/12/2024 Figure 17. Transverse section of the carpal tunnel Figure 20. Articulating surfaces of the acromioclavicular joint. METACARPAL BONES They articulate proximally with the carpals, and LIGAMENTS distally with the proximal phalanges. There are three main ligaments that strengthen and They are numbered; each associated with a digit: stabilize the acromioclavicular joint: ○ Metacarpal I – Thumb LIGAMENTS OF THE ACROMIOCLAVICULAR JOINT ○ Metacarpal II – Index finger Acromioclavicular runs horizontally from the ○ Metacarpal III – Middle finger ligament acromion to the lateral clavicle ○ Metacarpal IV – Ring finger covers the joint capsule, ○ Metacarpal V – Little finger reinforcing its superior aspect Each consists of a base, shaft and a head. Conoid runs vertically from the coracoid Medial and lateral surfaces of the metacarpals are ligament process of the scapula to the concave, allowing attachment of the interossei conoid tubercle of the clavicle muscles. Trapezoid runs from the coracoid process ligament of the scapula to the trapezoid line of the clavicle Table 6. Three main ligaments of the acromioclavicular joint. CORACOCLAVICULAR LIGAMENT Conoid + trapezoid ligaments Figure 18. Metacarpal bones. A very strong structure, effectively suspending (Head, Body, Base). the weight of the upper limb from the clavicle. PHALANGES The bones of the fingers Each phalanx consists of a base, shaft and head. The thumb has a proximal and distal phalanx The rest of the digits have proximal, middle and distal phalanges. Figure 21. The major ligaments of the acromioclavicular joint. MOVEMENTS The acromioclavicular joint allows a gliding movement in the superior/inferior and anteroposterior planes, along with a small amount of axial rotation. NOTE: As no muscle acts directly on the joint, all movements are passive, and are initiated by Figure 19. Phalanges of the hand. movement at other joints. II. JOINTS OF THE UPPER LIMB B. STERNOCLAVICULAR JOINT A. ACROMIOCLAVICULAR JOINT An articulation between the clavicle and the An articulation between the lateral end of the manubrium of the sternum. clavicle and the acromion of the scapula. Saddle-type synovial joint which acts to link the A plane type synovial joint. upper limb with the trunk. ARTICULATING SURFACES ARTICULATING SURFACES It has two atypical features: Formed by an articulation between three ○ Articular surfaces of the joint are lined with structures: fibrocartilage - as opposed to hyaline cartilage. ○ Sternal end of the clavicle ○ Joint cavity is partially divided by an ○ Manubrium of the sternum articular disc - a wedge of fibrocartilage ○ First costal cartilage (cartilage associated with suspended from the upper part of the capsule. the first rib) BATCH 2028 1A 5 ANATOMY LC 2: SKELETAL SYSTEM - UPPER LIMB Dr. BOLISLIS, M. 08/12/2024 Glenoid labrum - a fibrocartilage rim which deepens the glenoid fossa, reducing the disproportion in surfaces Figure 22. The articulating surfaces of the sternoclavicular joint. LIGAMENTS The ligaments of the sternoclavicular joint provide much of its stability. LIGAMENTS OF THE STERNOCLAVICULAR JOINT Figure 24. The articulating surfaces of the shoulder joint. Sternoclavicular reinforces the joint capsule ligaments anteriorly and posteriorly LIGAMENTS (anterior and Important in stabilizing the shoulder joint posterior) LIGAMENTS OF THE SHOULDER JOINT Interclavicular attaches to the sternal end of both Glenohumeral extend from the humerus to the ligament clavicles and reinforces the joint ligaments glenoid fossa reinforcing the joint capsule superiorly. (superior, middle capsule Costoclavicular attaches the first rib and costal and inferior) stabilize the anterior aspect of the ligament cartilage to the inferior surface of joint the clavicle. Coracohumeral extends from the base of the the main stabilizing force for the ligament coracoid process to the greater joint; resisting elevation of the tubercle of the humerus pectoral girdle supports the superior part of the Table 7. The three main ligaments of the sternoclavicular joint. joint capsule Transverse extends between the two tubercles humeral of the humerus ligament holds the tendon of the long head of the biceps in the intertubercular groove Coracoacromial extends between the acromion ligament and the coracoid process of the Figure 23. The major ligaments of the sternoclavicular joint. scapula, forming an arch-like structure over the shoulder joint (coracoacromial arch) MOVEMENTS resists superior displacement of The sternoclavicular joint has a large degree of the humeral head mobility, with several movements possible: Table 9. Four main ligaments of the glenohumeral (shoulder) joint. Elevation shrugging the shoulders or abducting the arm over 90º Depression drooping shoulders or extending the arm at the shoulder behind the body Protraction moving the shoulder girdle anteriorly Retraction moving the shoulder girdle posteriorly Rotation when the arm is raised over the head, the clavicle rotates passively as the scapula rotates Table 8. Possible movements done by the sternoclavicular joint. C. SHOULDER JOINT Figure 25. The ligaments of the shoulder joint. An articulation between the scapula and the humerus BURSAE Ball and socket-type synovial joint Synovial fluid filled sac, which acts as a cushion One of the most mobile joints in the body between tendons and other joint structures Function: decreases friction between tendons, ARTICULATING SURFACES bone and skin during movement Between the head of the humerus and the glenoid MAJOR BURSAE IN THE SHOULDER JOINT: cavity (or fossa) of the scapula Subacromial Alternate name: glenohumeral joint ○ Located deep in the deltoid and acromion, and The head of the humerus is much larger than the superficial to the supraspinatus tendon and glenoid fossa → wide range of motion at the cost joint capsule of instability ○ Reduces friction beneath the deltoid promoting free motion of the rotator cuff tendons. BATCH 2028 1A 6  ANATOMY LC 2: SKELETAL SYSTEM - UPPER LIMB Dr. BOLISLIS, M. 08/12/2024 Subscapular ○ Located between the subscapularis tendon & scapula ○ Reduces friction on the tendon during movement at the shoulder joint There are other minor bursae present between the tendons of the muscles around the joint. Figure 26. The major bursae of the shoulder joint Figure 27. Anterior and posterior views of the articulations of the elbow joint. MOVEMENTS BURSAE The shoulder joint is an extremely mobile joint, with There are many bursae in the elbow but few have a wide range of movement possible: clinical importance. Intratendinous olecranon - within the tendon of MUSCLES the triceps brachii MOVEMENT DESCRIPTION INVOLVED Subtendinous olecranon - between the Extension upper limb moves posterior deltoid olecranon and the tendon of the triceps brachii, backward in the latissimus dorsi reducing friction between the two structures during sagittal plane teres major extension and flexion of the arm Flexion upper limb moves pectoralis major Subcutaneous olecranon bursa – between the forward in the anterior deltoid sagittal plane coracobrachialis olecranon and the overlying connective tissue *biceps brachii weakly (implicated in olecranon bursitis) assists in forward flexion LIGAMENTS Abduction upper limb moves First 0-15° - Strengthens the joint capsule medially and laterally away from midline supraspinatus in the coronal plane Next 15-90° - LIGAMENTS OF THE ELBOW JOINT middle fibers of the Radial collateral found on the lateral side of the deltoid Ligament joint, extending from the lateral Past 90° - trapezius epicondyle, and blending with and serratus anterior (scapula the annular ligament of the needs to be radius (ligament from the rotated) proximal radioulnar joint) Adduction upper limb moves pectoralis major Ulnar collateral originates from the medial toward the midline latissimus dorsi Ligament epicondyle, and attaches to the in the coronal plane teres major coronoid process and olecranon Internal rotation towards the subscapularis of the ulna rotation midline, so that the pectoralis major Table 11. The ligaments of the elbow joint. thumb is pointing latissimus dorsi medially teres major anterior deltoid External rotation away from infraspinatus rotation the midline, so that teres minor the thumb is pointing laterally Circumduction moving the upper combination of the limb in a circle movements described above Table 10. Movements in the shoulder joint. Figure 28. Ligaments of the elbow joint. D. ELBOW JOINT Connects the upper arm to the forearm MOVEMENTS A hinge-type synovial joint The orientation of the bones forming the elbow joint Has a capsule enclosing the joint produces a hinge type synovial joint, which allows for Consists of two separate articulations: extension and flexion of the forearm: ○ Trochlear notch of the ulna and the trochlea Extension: triceps brachii and anconeus of the humerus Flexion: brachialis, biceps brachii, brachioradialis ○ Head of the radius and the capitulum of the humerus/radiocapitellar joint NOTE: Pronation and supination do not occur at the PRUJ - considered as a separate articulation elbow – they are produced at the radioulnar joints. (although found within same joint capsule of the elbow) BATCH 2028 1A 7 ANATOMY LC 2: SKELETAL SYSTEM - UPPER LIMB Dr. BOLISLIS, M. 08/12/2024 E. RADIOULNAR JOINT INTEROSSEOUS MEMBRANE Two locations in which the Sheet of connective tissue radius and ulna articulate in the that joins the radius and ulna forearm: together between the Proximal radioulnar joint radioulnar joints Distal radioulnar joint Midprone position ○ Position of function Both are classified as pivot ○ Fibers become taut when joints, responsible for pronation the forearm is in this and supination of the forearm. position Figure 29. The proximal radioulnar joint, Spans the distance between with the annular ligament. the medial radial border, and the lateral ulnar border PROXIMAL RADIOULNAR JOINT (PRUJ) There are small holes in the Located immediately distal to the elbow joint, and sheet, as a conduit for the enclosed within the same articular capsule forearm vasculature Figure 32. Interosseous membrane Formed by an articulation between the head of the radius and the radial notch of the ulna THREE MAJOR FUNCTIONS: Annular radial ligament 1. Holds the radius and ulna together during ○ Holds the radial head in place, forming a collar pronation and supination (providing additional around the joint stability) ○ Lined with a synovial membrane, reducing 2. Acts as a site of attachment for muscles in the friction during movement anterior & posterior compartments of the forearm 3. Transfers forces from the radius to the ulna Movement is produced by the head of the radius rotating within the annular ligament: F. WRIST JOINT Pronation: pronator quadratus and pronator teres An articulation between the radius and the carpal Supination: supinator and biceps brachii bones of the hand. AKA: Radiocarpal joint Condyloid-type (ellipsoidal) synovial joint Marks the transition between the forearm and the hand ARTICULATING SURFACES Formed by an articulation between: ○ Distal end of the radius and the articular disk ○ Proximal row of the carpal bones (EXCEPT the pisiform) Form a convex surface, which fits into the Figure 30. Articulating surfaces of the proximal radioulnar joint. concave shape of the radius and articular disk. Articular disk (a fibrocartilaginous ligament) DISTAL RADIOULNAR JOINT (DRUJ) ○ prevents the ulna from articulating with the Located just proximally to the wrist joint carpal bones An articulation between the ulnar notch of the Instead, the ulna articulates with the radius just radius, and the ulnar head. proximal to the wrist - at the distal radioulnar joint. Ligaments strengthening the joint: ○ Anterior & posterior ligaments LIGAMENTS ○ Articular disk (fibrocartilaginous ligament) There are 4 main ligaments located at the wrist joint: - Binds the radius and ulna together, and holds them together during movement at LIGAMENTS OF THE WRIST JOINT the joint Palmar passes from the radius to both rows of the - Separates the distal radioulnar joint from radiocarpal carpal bones the wrist joint increases stability and ensures that the hand follows the forearm during DRUJ is a pivot joint just like PRUJ supination. Movements: pronation and supination Dorsal originates from medial epicondyle, and The ulnar notch of the radius slides anteriorly radiocarpal attaches to the coronoid process and over the head of the ulnar during such movements olecranon of the ulna Ulnar runs from the ulnar styloid process to the collateral triquetrum and pisiform. prevent excessive radial (lateral) deviation of the hand Radial runs from the radial styloid process to the collateral scaphoid and trapezium. prevent excessive ulnar (medial) deviation to the hand Table 12. The four main ligaments of the radiocarpal joint. Figure 31. Articular surfaces of the distal radioulnar and wrist joint. BATCH 2028 1A 8 ANATOMY LC 2: SKELETAL SYSTEM - UPPER LIMB Dr. BOLISLIS, M. 08/12/2024 JOINT CAPSULE Loose fibrous joint capsule - covers each metacarpophalangeal joint where it attaches close to the margins of the articulating surfaces. Collateral ligaments - reinforces the joint capsules since it is thicker on the medial and lateral aspects. LIGAMENTS The metacarpophalangeal joint capsule is reinforced Figure 33. Palmar view of the ligament of the wrist joint. by several ligaments and adjacent musculoskeletal structures. MOVEMENTS The ellipsoidal (condyloid) type synovial joint LIGAMENTS OF THE allows for movement along two axes. METACARPOPHALANGEAL JOINTS All the movements of the wrist are performed by Collateral metacarpo reinforces the medial and muscles of the forearm. phalangeal ligaments lateral aspects of the joint capsule MOVEMENT MUSCLES INVOLVED Palmar ligament reinforces the anterior aspect Flexion Flexor carpi ulnaris, flexor carpi of the joint capsule. radialis, with assistance from the a dense fibrocartilaginous flexor digitorum superficialis thickening that strongly Extension Extensor carpi radialis longus and adheres to the palmar surface brevis and extensor carpi ulnaris of the base of each proximal with assistance from the extensor phalanx digitorum blends on its sides with the Adduction Extensor carpi ulnaris and flexor collateral ligaments. carpi ulnaris Deep transverse connects the palmar Abduction Abductor pollicis longus, flexor metacarpal ligaments ligaments of the 2nd to 5th carpi radialis, extensor carpi metacarpophalangeal joints. radialis longus and brevis links the digits together which Table 13. Possible movements done by the wrist joint. increases its stability Table 14. Important ligaments of the metacarpophalangeal joint. The posterior aspect of the joint capsule receives fibers from the overlying tendons of the extensor muscles of the forearm (extensor pollicis longus, extensor indicis, extensor digitorum and extensor digiti minimi). Figure 34. A demonstration of the movements of the wrist joint. G. METACARPOPHALANGEAL JOINT An articulation between the metacarpal head and the base of the proximal phalanx. There are five joints in each hand - one for each digit. Condyloid synovial joint Figure 36. Ligaments and joint capsule of the metacarpophalangeal joint MOVEMENTS Each metacarpophalangeal joint has two planes of motion. All movements at the joint are produced by muscles of the forearm and hand. Figure 35. The articulating surfaces of the metacarpophalangeal joints of the hand. ARTICULATING SURFACES Metacarpal head - -large articulating surface, convex in shape Base of proximal phalanx - -smaller articulating surface, concave in shape. Both metacarpal & phalangeal articular surfaces are lined by hyaline cartilage. Figure 37. Movements produced by the thumb. BATCH 2028 1A 9 ANATOMY LC 2: SKELETAL SYSTEM - UPPER LIMB Dr. BOLISLIS, M. 08/12/2024 LIGAMENTS MUSCLES INVOLVED The proximal interphalangeal joint (PIPJ) capsule is MOVEMENT THUMB DIGITS 2-5 strengthened by the surrounding ligaments: Flexion Flexor pollicis Flexor digitorum brevis and longus superficialis, flexor LIGAMENTS OF THE digitorum profundus, PROXIMAL INTERPHALANGEAL JOINTS lumbricals, flexor Proper Located on the radial and ulnar digiti minimi (5th digit) collateral aspect of the joint Extension Extensor pollicis Extensor digitorum, ligaments Prevent excessive adduction and brevis and longus extensor indicis (2nd abduction at the PIPJ. digit), extensor digiti Arise from the head of the proximal minimi (5th digit) and pass volarly onto the middle Adduction Adductor pollicis Palmar interossei phalanx, along the lateral aspect of muscles the joint. Abduction Abductor pollicis Dorsal interossei Accessory Accompanies each collateral longus and brevis muscles, abductor digiti minimi (5th digit) collateral ligament, originating from the same Axial rotation Simultaneous None ligament point, and extends anteriorly to contraction of the attach to the volar plate. flexor pollicis brevis Volar plate Thick fibrocartilaginous structure & abductor pollicis which arches across the base of the brevis PIPJ in a “U” shape. Opposition Opponens pollicis None Prevents excessive hyperextension Table 15. The muscles involved in the movement of the of the joint. metacarpophalangeal joints. Attached to the head of the proximal phalanx via the checkrein ligaments and inserts distally into the volar base of the middle phalanx. Table 16. The ligaments surrounding the proximal interphalangeal joint. Figure 38. The flexor digitorum profundus and flexor pollicis longus produce flexion at the MCPJs. H. PROXIMAL INTERPHALANGEAL JOINT The articulation between the proximal and middle phalanx in the hand. Present in all digits except the thumb Synovial hinge joint ○ permits the flexion and extension in center fingers, contributing to fine motor control Figure 39. The ligaments of the proximal interphalangeal joint. MOVEMENTS Given the nature of hinge joints and the stability of the PIPJ, it only moves in one plane: Flexion: ○ Healthy PIPJ: can flex to between 100-110° ○ Primary muscle: flexor digitorum superficialis ○ Secondary driver: flexor digitorum profundus Figure 39. The proximal (primarily flexes the distal interphalangeal interphalangeal joints of the joint). hand. Extension: back to 0 degrees ○ Muscles involved: extensor digitorum, lumbricals, and interossei muscle. ○ Index finger of the PIPJ gets further assistance from extensor indicis. ARTICULATING SURFACES Head of the proximal phalanx - formed by two curved condylar processes which form a shallow Reference(s): Wineski, L. E. (2019). Snell’s Clinical Anatomy By Regions (10th groove in the middle. ed.). Philadelphia (PA): Wolters Kluwer. Base of the middle phalanx - formed by two Bones of the Upper Limb. TeachMeAnatomy. (n.d.). opposing concave sections which form a raised https://teachmeanatomy.info/upper-limb/bones/ ridge. Joints of the Upper Limb. TeachMeAnatomy. (n.d.). https://teachmeanatomy.info/upper-limb/joints/ ○ This ridge fits neatly into the proximal groove and provides great intraarticular stability. BATCH 2028 1A 10