Anatomy of the Upper Limb PDF

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UM6P

Dr. BOANIMBEK Baudouin

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human anatomy anatomy notes upper limb anatomy biological science

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This document provides an introduction to human anatomy, focusing on the upper limb. It details the organization and structure of the upper limb, including bones, joints, muscles and blood vessels. The document also covers fundamental concepts about the human body and incorporates numerous anatomical diagrams.

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Introduction to Anatomy Dr. BOANIMBEK Baudouin Trauma and Orthopaedic department objectives Fundamentals of Anatomy gives students instruction in the organization and structures of the human body. Learn to describe the structure and function of the major bones, joints, muscles and soft ti...

Introduction to Anatomy Dr. BOANIMBEK Baudouin Trauma and Orthopaedic department objectives Fundamentals of Anatomy gives students instruction in the organization and structures of the human body. Learn to describe the structure and function of the major bones, joints, muscles and soft tissue structures of the upper limb. Be able to describe the basic movements of the body. Cover the name, placement and movement of bones, joints and muscles of the upper limb. A brief introduction Anatomy is the identification and description of the structures of the body. It is a branch of biology and medicine. 2 fundamental sciences: Anatomy and physiology normal functioning and structure; essential to recognize what is normal and then what is not normal in order to give the good cure. Anatomy can be divided into four main parts: microscopic anatomy refers to histology, gross or macroscopic anatomy ( refers to the structures that can be seen with a naked eye without using devices like a microscope), developmental anatomy refers to embryology, genetic New vocabulary, new terminology A brief introduction 11 organ systems The basics Anatomical terms The Anatomical Anatomical Terms Generality Anatomical Planes of movement Position of Location Generality There are a total of 206 bones in the adult human body. They range in size from the tiniest, the the stapes (found in the middle ear), to the largest, the femur that forms our thigh. Bones form the scaffolding that hold the body together and allow it to move. But bones have other key roles, including protecting vital organs, storing minerals, and providing an environment for creating bone marrow. There are more than 600 muscles in the human body. B- Functions of Bones Framework – Supports muscle, fat and skin Protection – Surrounds vital organs like skull, ribs, pelvis Movement – Muscles attach to bones to provide movement Mineral homeostasis – Stores and maintain minerals (Calcium & phosphorus) Production of blood cells – Red bone marrow – produes Red and white blood cells and platelets Storage – Calcium – Yellow bone marrow – has adipocytes – stores fat. I- The Anatomical Position The standard anatomical position is described as follow: Standing upright and facing forward. Arms straight, hands held by the hips with palms facing forward. Feet together and parallel, toes pointing forward. A clear mechanism of describing the location of structures II- Anatomical Planes There are three basic reference planes used in anatomy: the sagittal plane, the coronal plane, and the transverse plane. They are used to describe the location of structures in human anatomy also to describe how the body moves. II- Anatomical Planes Sagittal Plane Coronal Plane Transverse Plane A vertical plane which passes is often referred to as the frontal divides the body into superior and through the body longitudinally. It plane; It divides the body into a inferior portions. It is a horizontal divides the body into a left section front (anterior) section and back plane through the center of the and a right section. (posterior) section. body and is parallel to the ground. III- Anatomical Terms of Location are descriptive terms to help identify relative positions or directions, They help to avoid any ambiguity that can arise when describing the location of structures. Medial and Lateral: Medial means towards the midline, lateral means away from the midline. Anterior and Posterior: Anterior refers to the ‘front’, and posterior refers to the ‘back’ Superior and Inferior: refer to the vertical axis. Superior means ‘higher’, inferior means ‘lower’. Proximal and Distal: are used in structures that are considered to have a beginning and an end. proximal means closer to its origin, distal means further away. IV- Anatomical terms of movement There are general anatomical terms that can be used to describe most movements the body makes. Flexion refers to a movement that decreases the angle between two body parts. Extension refers to a movement that increases the angle between two body parts. Abduction is a movement away from the midline. Adduction is a movement towards the midline. Medial rotation is a rotational movement towards the midline. Lateral rotation is a rotating movement away from the midline. Pronation describes a rotational movement of the forearm that results in the palm facing posteriorly (when in the anatomic position). IV- Anatomical Supination describes the motion of turning the palm anteriorly. terms of movement Inversion involves the movement of the sole towards the median plane – so that the sole faces in a medial direction. Eversion involves the movement of the sole away from the median plane – so that the sole faces in a lateral direction. Anatomy of the upper limb Dr. BOANIMBEK Baudouin Trauma and Orthopaedic department Plan Generality A- Basics B- Osteology and arthrology of the upper limb C- Muscles of the upper limb D- Blood Vessels, Lymphatics and nerves of the Upper Limb F- Anatomical Areas E- Surface anatomy Classification of Bones The bones of the body come in a variety of sizes and shapes. The four principal types of bones are long, short, flat and irregular. Long Bones: They consist of a long shaft with two bulky ends or extremities. They are primarily compact bone but may have a large amount of spongy bone at the ends or extremities. Short Bones: are roughly cube shaped with vertical and horizontal dimensions approximately equal. They consist primarily of spongy bone, which is covered by a thin layer of compact bone. Flat Bones: are thin, flattened, and usually curved. Irregular Bones: Bones that are not in any of the above three categories are classified as irregular bones Gross Anatomy of a Long Bone Diaphysis – Shaft – Composed of compact bone Epiphysis – Ends of the bone – Composed mostly of spongy bone The Skeletal system A- Osteology of the upper limb The scapula Sesamoid The clavicle bones The The phalanges humerus The The ulna metacarpal The carpal The radius bones I- The scapula I- The scapula The scapula is a flat, triangular-shaped bone (also known as the "shoulder blade"). It articulates with the humerus at the glenohumeral joint, and with the clavicle at the acromioclavicular joint. In doing so, the scapula connects the upper limb to the trunk. The scapula has three angles (superior/medial, lateral, inferior), three borders (medial, lateral/axillary, and superior), and two surfaces (ventral and dorsal). The costal (anterior) surface of the scapula faces the ribcage, and has a large concavity called the subscapular fossa where the subscapularis attaches. the coracoid process is a hook-like projection, which lies just underneath the clavicle; it is an attachment point for muscles and ligaments. I- The scapula The dorsal surface divides into two unequal parts via the scapular spine which runs across from the posterior scapula before forming the acromion. Above the spine is the supraspinous fossa and below it is the infraspinous fossa. The acromion is an oblong continuation of the spine that runs laterally then anteriorly above the supraspinous fossa and is the summit of the shoulder on palpation. The lateral angle of the scapula is the location of the glenoid cavity, It is the site of the glenohumeral joint. I- The scapula II-The clavicle II- The clavicle The clavicle extends between the sternum (medial end) and the acromion of the scapula (lateral end). It serves as a connection between the axial and appendicular skeleton. The clavicle is a slender bone with an ‘S’ shape. II-The clavicle III- The humerus III- The humerus The humerus is the longest and largest bone of the upper limb and defines the human brachium (arm). The proximal aspect of the humerus articulates with the glenoid fossa of the scapula, forming the glenohumeral joint. Distally, at the elbow joint, the humerus articulates with the head of the radius and trochlear notch of the ulna. III.1 The proximal humerus The proximal humerus is marked by a head, anatomical neck, surgical neck, greater and lesser tuberosity and intertubercular sulcus. The upper end of the humerus consists of the head; Just inferior to the head of the humerus is the anatomical neck of the humerus, which divides the head of the humerus from the greater and lesser tubercles. The surgical neck extends from just distal to the tuberosities to the shaft of the humerus. The axillary nerve and circumflex humeral vessels lie against the bone here Continuing distally is the cylindrical-shaped shaft of the humerus, III.2 The humerus shaft which contains a deltoid tubercle on its lateral aspect and the radial groove on its posterior aspect, where lies the radial nerve. Wrist drop sign III.3 The distal humerus The distal portion of the humerus ends with an area referred to as the condyle, which is composed of the trochlea, capitulum, olecranon, coronoid and radial fossae. the lateral and medial epicondyles can be palpated at the elbow. The ulnar nerve passes in a groove on the posterior aspect of the medial epicondyle where it is palpable. On the anterior lateral surface of the condyle is the lateral capitulum, which articulates with the head of the radius bone, and on the anterior medial surface of the condyle is the trochlea, which articulates the trochlear notch of the ulna bone the coronoid, radial and olecranon fossae accommodate the forearm bones during flexion or extension at the elbow. The humerus IV- The Ulna IV-The Ulna The ulna is one of the two forearm long bones that, in conjunction with the radius, make up the antebrachium. The bone spans from the elbow to the wrist on the medial side of the forearm when in anatomical position. The ulna acts as the stabilising bone, with the radius pivoting to produce movement. IV.1 The proximal Ulna The proximal end of the ulna articulates with the trochlea of the humerus, it’s sometimes referred to as the head of the ulna. It contains the: Olecranon: is the tip of the ulna and serves as the insertion point for the triceps Coronoid process: this ridge of bone projects outwards anteriorly Trochlear notch: formed by the olecranon and coronoid process Radial notch: located on the lateral surface of the trochlear notch IV.2 The shaft and distal ulna The shaft is the long middle portion of the ulna. It is the site of attachment for the interosseous membrane, which spans the distance between the two forearm bones. The distal end of the ulna ends 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. V- The Radius V- The Radius The radius is one of two long bones that make up the human antebrachium. It lies laterally and parallel to ulna. The radius pivots around the ulna to produce movement at the proximal and distal radio-ulnar joints. V.1 The proximal Radius The proximal end of the radius articulates in both the elbow and proximal radioulnar joints. It contains the: Head of radius: A disk shaped structure, with a concave articulating surface Distal to the radial head is the neck of the radius and radial tuberosity - an oval prominence that is the site of attachment of the biceps brachii muscle. Distal to the radial tuberosity is the shaft, it expands in diameter as it moves distally. V.2 The distal Radius In the distal region, the radial shaft expands to form a rectangular end. The lateral side projects distally as the styloid process; In the medial surface, there is a concavity, called the ulnar notch, which articulates with the head of ulna. The distal radius articulates with the scaphoid and lunate carpal bones. This makes up the wrist joint. Fractures of the distal radius account for some of the most common fractures. Distal radius fractures VI- The Carpal Bones VI- Carpal Bones The carpal bones are bones of the wrist that connect the distal aspects of the radial and ulnar bones to the bases of the five metacarpal bones of the hand. There are eight carpal bones, which divide into two rows: a proximal row and a distal row. Proximal Row (lateral to medial): the scaphoid, lunate, triquetrum, and pisiform Distal Row (lateral to medial): the trapezium, trapezoid, capitate, and hamate. Collectively, the carpal bones form an arch in the coronal plane. Proximally, the scaphoid and lunate articulate with the radius to form the wrist joint. In the distal row, all of the carpal bones articulate with the metacarpals. VII- The metacarpal bones VII- The metacarpal bones The metacarpal bones are five bones that form the middle part of the skeleton of the hand. They are numbered, and each associated with a digit: First metacarpal or metacarpal I - associated with a thumb; Second metacarpal (II) - with an index finger; Third metacarpal (III) - associated with a middle finger; Fourth metacarpal (IV) - with a ring finger; Fifth metacarpal (V) - associated with a little finger. Each metacarpal consists of a base, shaft and a head. The medial and lateral surfaces of the metacarpals are concave, allowing attachment of the interossei muscles. VII- The metacarpal bones VIII-The phalanges The phalanges are the bones of the fingers. VIII- The phalanges The thumb has a proximal and distal phalanx, while the rest of the digits have proximal, middle and distal phalanges. IX-Sesamoid A sesamoid bone is a small bone commonly found embedded within a muscle or tendon near joint surfaces Bones functioning as a pulley to alleviate stress on that particular muscle or tendon. B- Arthrology The shoulder glenohumeral joint The Elbow joint The wrist joint Joints of the hand Carpometacarpal joints acromioclavicular joint Metacarpophalangeal joints of the upper sternoclavicular joint scapulothoracic joint The interphalangeal joints limb Introduction Joints can be classified by the degree of movement: Synarthrosis –immovable joint, Amphiarthrosis –slightly moveable and Diarthrosis –freely moveable. A synovial joint is characterised by the presence of a fluid-filled joint cavity contained within a fibrous capsule. It is the most common type of joint found in the human body. Synovial joints can be sub-classified into several different types, depending on the shape of their articular surfaces and the movements permitted: Introduction Hinge–permits movement in one plane–usually flexion and extension. E.g. elbow joint, ankle joint, knee joint. Saddle–named due to its resemblance to a saddle on a horse’s back. It is characterised by opposing articular surfaces with a reciprocal concave-convex shape. E.g. carpometacarpal joints. Plane–the articular surfaces are relatively flat, allowing the bones to glide over one another.E.g. acromioclavicular joint, subtalar joint. Pivot–allows for rotation only. It is formed by a central bony pivot, which is surrounded by a bony-ligamentous ringE.g. proximal and distal radioulnar joints. Introduction Condyloid–contains a convex surface which articulates with a concave elliptical cavity. They are also known as ellipsoid joints. E.g. wrist joint, metacarpophalangeal joint, metatarsophalangeal joint. Ball and Socket–where the ball-shaped surface of one rounded bone fits into the cup-like depression of another bone. It permits free movement in numerous axes. E.g. hip joint, shoulder joint. The shoulder is extremely mobile and made up of several joints that work together. Four joints are present in the shoulder: the I- The shoulder sternoclavicular (SC), acromioclavicular (AC), and scapulothoracic joints, and glenohumeral joint. I.1 glenohumeral joint The glenohumeral joint is the main joint of the shoulder. Synovial joint, and one of the most mobile joints in the human body. It is formed by an articulation between the head of the humerus and the glenoid cavity (or fossa) of the scapula. It is a shallow articulation, as the fossa accommodates less than one-third of the humeral head. To reduce the disproportion in surfaces, the glenoid fossa is deepened by a fibrocartilage rim – called the glenoid labrum. I.1 glenohumeral joint The joint capsule is a fibrous sheath which encloses the structures of the joint. The synovial membrane lines the inner surface of the joint capsule and produces synovial fluid to reduce friction between the articular surfaces. Ligaments play an important role in stabilising the shoulder joint: Glenohumeral ligaments (superior, middle and inferior), Coracohumeral ligament, Transverse humeral ligament, Coracoacromial ligament. They act to reinforce the joint capsule. I.1 glenohumeral joint The glenohumeral joint is stabilized by the rotator cuff muscles that attach to the joint capsule, as well as the tendons of the biceps and triceps brachii. The rotator cuff contains four muscles: Supraspinatus, Infraspinatus, Teres minor, Subscapularis. I.1 glenohumeral joint Blood Supply: The shoulder joint is supplied by the anterior and posterior circumflex humeral arteries which are both branches of the axillary artery. Shoulder dislocations represent 50 percent of all major joint I.1 glenohumeral joint dislocations, it is the most common dislocation in the human body. I.2 acromioclavicular joint The acromioclavicular (AC) joint articulates the lateral end of the clavicle with the acromion. The AC joint is a plane type synovial joint which allows only gliding movement. The AC joint is surrounded by a capsule and lined by a synovial membrane. Three main ligaments stabilize the joint. The acromioclavicular ligament, it mainly serves to provide horizontal stability. The coracoclavicular ligaments complex consists of the conoid and trapezoid ligaments. They insert on the posteromedial and anterolateral region of the undersurface of the distal clavicle, respectively, It mainly serves to provide vertical stability. I.2 acromioclavicular joint The sternoclavicular joint is a synovial joint between the medial clavicle, the I.3 sternoclavicular joint manubrium and the first costal cartilage that joins the upper limb with the axial skeleton. I.4 scapulothoracic joint The scapulothoracic joint is not a true anatomical joint. It unites Anterior surface of scapula, superolateral surface of posterior thoracic wall. Concerning that it is not a true joint, the scapulothoracic joint doesn’t have specific articular surfaces, ligaments nor the joint capsule. I.5 Range of motion The shoulder joint is an extremely mobile joint, with a wide range of movement possible: Extension (upper limb backwards in sagittal plane): The usual range of motion is 45 to 60 degrees. Flexion (upper limb forwards in sagittal plane): The normal range of motion is 180 degrees. Abduction (upper limb away from midline in coronal plane): The normal range of motion is 150 degrees Adduction (upper limb towards midline in coronal plane): The normal range of motion is 30 to 50 degrees Internal rotation (rotation towards the midline): The normal range of motion is 70 to 90 degrees External rotation (rotation away from the midline) The normal range of motion is 90 degrees Circumduction (moving the upper limb in a circle) – produced by a combination of the movements described above II- The Elbow joint The elbow joint consists of three separate articulations: the humeroulnar joint, the humeroradial joint and the proximal radioulnar joint. II.1 Articulating Surfaces The humeroulnar joint is the main joint of the elbow. It is formed by an articulation between the Trochlear notch of the ulna and the trochlea of the humerus. the humeroradial joint is the joint between the capitulum of the humerus with the head of the radius. the proximal radioulnar joint, It is articulation between the head of the radius and the radial notch of the ulna II.2 Joint capsule and ligaments As a synovial joint, the elbow has a capsule enclosing the joint. The inner layer of the capsule forms a synovial membrane. The joint capsule of the elbow is strengthened by ligaments medially and laterally. The lateral (radial) collateral ligament: extending from the lateral epicondyle, and blending with the annular ligament of the radius The medial (ulnar) collateral ligament: from the medial epicondyle, to the coronoid process and olecranon. The annular ligament stabilizes the proximal radioulnar joint and originates and inserts at the sigmoid notch of the ulna as it wraps around the neck of the radius. II.3 Blood supply The elbow joint receives a rich arterial supply from a surrounding network of vessels, which is formed by branches of the brachial artery. II.4 Range of motion The elbow joint allows us to perform flexion– extension and pronation–supination movement. Extension: normal active elbow extension range of motion is 0o i.e. fully straight Flexion: normal active elbow flexion range of motion is 140o-150o i.e. fully bent Pronation: normal active pronation range of motion is 75o-85o Supination: normal active supination range of motion is 80o-90o III- The wrist joint The wrist joint also referred to as the radiocarpal joint connects and serves as a transition point between the forearm and hand. III.1 Articulating Surfaces The wrist joint is formed by an articulation between: Distal end of the radius and the articular disk (a fibrocartilaginous ligament) Proximal row of the carpal bones (except the pisiform). The proximal articulation forms a concave shape composed of a combination between the distal end of the radius and articular disk. Note that the ulna is not part of the wrist joint itself, as it articulates with the distal radius just proximal to the wrist via the distal radioulnar joint. III.2 Joint capsule and ligaments Surrounding the wrist joint is a dual-layered joint capsule, The outer layer is fibrous and attaches to the radius, ulna, and carpal bones. The inner layer forms a synovial membrane which secretes synovial fluid and lubricates the joint. There are four main ligaments located at the wrist joint: Palmar radiocarpal: connect the radius to both the proximal and distal rows of carpal bones. Dorsal radiocarpal: is similar to the palmar ligament. Ulnar collateral: Runs from the ulnar styloid process to the triquetrum and pisiform. Radial collateral: runs from the radial styloid process to the scaphoid and trapezium bones. III.3 blood supply The wrist joint receives blood from branches of the dorsal and palmar carpal arches, which are derived from the ulnar and radial arteries. III.4 Range of motion The wrist joint is a highly mobile joint to allow the hand to move in several directions. flexion: 80°-90° extension: 70°-90° Radial deviation: 15° Ulnar deviation: 30°-45 Pronation: 90° (occurs in the elbow) Supination: 90° (occurs in the elbow) IV- Joints of the hand Carpometacarpal joints metacarpophalangeal joint (MCP) proximal interphalangeal joint (PIP) distal interphalangeal joint (DIP) – IV.1 Carpometacarpal joints The carpometacarpal (CMC) joints are articulations between the carpal bones and metacarpal bones of the hand. Metacarpals 2 and 3 are almost immobile, metacarpal 4 is capable of a small degree of gliding, while metacarpal 5 can glide to such great extent as to produce flexion and rotation. The four CMC joints are surrounded and stabilized by a common fibrous capsule. This fibrous capsule is lined by a synovial membrane. The CMC joints are stabilized by three sets of ligaments: dorsal carpometacarpal ligaments, palmar carpometacarpal ligaments and interosseous ligaments. IV.1 Carpometacarpal joints The trapeziometacarpal joint is the articulation between the trapezium and the base of the first metacarpal bone, it is the CMC of the thumb. The trapeziometacarpal joint is enclosed by a fibrous capsule that attaches to the margins of the articular surfaces. The inner surface of the capsule is lined by a synovial membrane. The joint is reinforced by the two sets of ligaments: Radial carpometacarpal ligament, Anterior and posterior oblique ligaments. The trapeziometacarpal joint is a multiaxial joint: Flexion-extension (40°-50°), Abduction-adduction (80°), Axial rotation (70° à 110°). IV.1 Carpometacarpal joints IV.2 metacarpophalangeal joints The metacarpophalangeal joint is an articulation between the metacarpal head and the base of the proximal phalanx. Each metacarpophalangeal joint is covered by a fibrous joint capsule. The capsule is reinforced by collateral ligaments and adjacent musculoskeletal structures: collateral metacarpophalangeal ligaments (in the medial and lateral sides), the palmar ligament (anterior aspect), tendons of the extensor muscles (posterior aspect) Each metacarpophalangeal joint has two planes of motion, It allows for flexion, extension, abduction, adduction, and axial rotation (thumb only) IV.2 metacarpophalangeal joints IV.3 The interphalangeal joints The interphalangeal joints of the hand are synovial hinge joints. The proximal interphalangeal joint (PIPJ or PIJ) is located between the proximal and middle phalanges. the distal interphalangeal joint (DIPJ or DIJ) is found between the middle and distal phalanges. Surrounding each interphalangeal joint is a fibrous joint capsule. two collateral ligaments and a palmar ligament, also known as a palmar/volar plate. Dorsally, the joint capsule is strengthened by a broadening of the extensor tendons. C- Muscles of the Upper Limb I- Muscles of the Pectoral Region The pectoral region is located on the anterior chest wall. It contains four muscles that connect the upper extremities to the anterior and lateral thoracic walls: the pectoralis major, pectoralis minor, serratus anterior and subclavius. I.1 Pectoralis Major The pectoralis major is the most superficial muscle in the pectoral region. Origin: Clavicular head –anterior surface of the medial clavicle. Sternocostal head –anterior surface of the sternum, the superior six costal cartilages and the aponeurosis of the external oblique muscle. Insertion: Crest of greater tubercle of humerus. Action: adduction, internal rotation, flexion of the arm, Draws scapula anteroinferiorly Innervation: Lateral and medial pectoral nerves. I.2Pectoralis Minor The pectoralis minor lies underneath the pectoralis major. Origin: the 3rd-5th ribs Insertion: the coracoid process of the scapula. Action: draws scapula anteroinferiorly, stabilizes scapula on thoracic wall Innervation: Medial pectoral nerve. 1.3 Serratus Anterior The serratus anterior muscle is a fan- shaped muscle at the lateral wall of the thorax. Origin: the lateral aspects of ribs 1-8. Insertion: the costal (rib facing) surface of the medial border of the scapula. Action: Rotates the scapula, allowing the arm to be raised over 90 degrees. Innervation: Long thoracic nerve. I.4 Subclavius The subclavius muscle is a short, triangular muscle of the thoracic wall that lies underneath the clavicle. Origin: Costal cartilage, sternal end of rib 1. insertion: Anteroinferior surface of middle third of clavicle Action: Anchors and depresses clavicle Innervation: Nerve to subclavius. The muscles of the shoulder support and produce the movements of the shoulder girdle (The shoulder girdle, consisting of the collar bone (clavicle) and the shoulder II- muscles of the blade (scapula) provides the bony link between the arm and the trunk). They can be classified into extrinsic and intrinsic categories. shoulder region Extrinsic – originate from the torso and attach to the bones of the shoulder. Intrinsic: originate from the bones of the shoulder II- Muscles of the shoulder region II.1 Extrinsic muscles: These muscles are organised into a superficial and a deep layer. The superficial layer contains 2 muscles: the trapezius muscle and the latissimus dorsi The deep layers contains 3 muscles: the levator scapulae and the rhomboids (Major and minor) II.1.1 Trapezius The trapezius muscle is a large, triangular, paired muscle located on the posterior aspect of the neck and thorax. Origin: Originates from the skull, nuchal ligament and the spinous processes of C7-T12. Insertion: The fibres attach to the clavicle, acromion, and the scapula spine Action: the upper fibres elevate an rotate the scapula, The middle fibres retract the scapula and the lower fibres pull the scapula inferiorly. Innervation: Motor innervation is from the accessory nerve. It also receives proprioceptor fibres from C3 and C4 spinal nerves. II.1.2 Latissimus Dorsi The latissimus dorsi muscle is the widest muscle in the human body. Origin: Vertebral part: Spinous processes of vertebrae T7-T12, Thoracolumbar fascia Iliac part: Posterior third of crest of ilium Costal part: Ribs 9-12 Scapular part: Inferior angle of scapula Insertion: The fibres converge into a tendon that attaches to the intertubercular sulcus of the humerus. Action: Arm internal rotation, Arm adduction, Arm extension; Assists in respiration Innervation: Thoracodorsal nerve. II.1.3 Levator Scapulae Levator scapulae is a long and slender muscle, it is considered to be a muscle of scapular motion. Origin: Transverse processes of vertebrae C1-C4 Insertion: medial border of the scapula. Action: Elevates the scapula, rotates glenoid cavity inferiorly. Innervation: Dorsal scapular nerve. II.1.4 Rhomboids The rhomboids are two bilateral, superficial muscles located in the upper back. They consist of two functionally similar muscles called rhomboid minor and rhomboid major. Origin: Rhomboid minor: Nuchal ligament, Spinous processes Rhomboid major: Spinous process of vertebrae T2-T5 Insertion Rhomboid minor: Root (medial end) of spine of scapula Rhomboid major: Medial border of scapula Actions: Retracts and rotates the scapula. Innervation: Dorsal scapular nerve. II- Muscles of the shoulder region II.2 Intrinsic muscle: There are six muscles in this group – the deltoid, teres major, and the four rotator cuff muscles (supraspinatus, infraspinatus, subscapularis and teres minor). II.2.1 Deltoid The deltoid is a thick, triangular shoulder muscle. It can be divided into an anterior, middle and posterior part. It gets its name because of its similar shape to the Greek letter ‘delta’ (Δ). Origin: Lateral 1/3 of Clavicle (clavicular part), Acromion (acromial part), Spine of Scapula. Insertion: the deltoid tuberosity on the lateral aspect of the humerus. Actions: Anterior fibres – flexion and medial rotation. Posterior fibres – extension and lateral rotation. Middle fibres – the major abductor of the arm. Innervation: Axillary nerve II.2.2 Teres Major The teres major is a thick muscle of the shoulder joint. Origin: the posterior surface of the inferior angle of the scapula Insertion: intertubercular sulcus (medial lip) of the humerus. Action: Adducts and extends at the shoulder, and medially rotates the arm Innervation: Lower subscapular nerve II.2.3 Rotator Cuff Muscles The rotator cuff is a group of muscles in the shoulder that allow a wide range of movement while maintaining the stability of the glenohumeral joint. Supraspinatus Attachments: Originates from the supraspinous fossa of the scapula, attaches to the greater tubercle of the humerus. Actions: Abducts the arm 0-15o, and assists deltoid for 15-90o Innervation: Suprascapular nerve. Infraspinatus Attachments: Originates from the infraspinous fossa of the scapula, attaches to the greater tubercle of the humerus. Actions: Laterally rotates the arm. Innervation: Suprascapular nerve II.2.3 Rotator Cuff Muscles Subscapularis Attachments: Originates from the subscapular fossa,. It attaches to the lesser tubercle of the humerus. Actions: Medially rotates the arm. Innervation: Upper and lower subscapular nerves. Teres Minor Attachments: Originates from the posterior surface of the scapula, adjacent to its lateral border. It attaches to the greater tubercle of the humerus. Actions: Laterally rotates the arm. Innervation: Axillary nerve. III- Muscles of the upper arm The (upper) arm muscles are a group of four muscles located in the region between the shoulder and elbow joints. Three muscles are in the anterior compartment (biceps brachii, brachialis, coracobrachialis), and one in the posterior compartment (triceps brachii). III.1 Biceps Brachii It gets its name from its two heads, each of which has a separate origin. Origin: Long head originates from the supraglenoid tubercle of the scapula, and the short head originates from the coracoid process of the scapula. Insertion: Radial tuberosity of the radius, Deep fascia of forearm. Action: Flexion and supination of the forearm at the elbow joint. minimal role in flexion of the shoulder. Innervation: Musculocutaneous nerve III.2 Coracobrachialis The coracobrachialis muscle lies deep to the biceps brachii in the arm. Origin: Coracoid process of the scapula Insertion: Anteromedial surface of the humerual shaft. Action: Flexion of the arm at the shoulder, and weak adduction. Innervation: Musculocutaneous nerve III.3 Brachialis The brachialis muscle lies deep to the biceps brachii and is found more distally than the other muscles of the arm. Origin: Distal half of anterior surface of humerus Insertion: Coronoid process of the ulna; Tuberosity of ulna. Action: Strong flexion of forearm at the elbow joint Innervation: Musculocutaneous nerve, with contributions from the radial nerve. III.4 Triceps Brachii the triceps brachii is the muscle of the posterior compartment of the upper arm. Origin: Long head - infraglenoid tubercle of the scapula, Medial head - posterior surface of the humerus (inferior to radial groove), Lateral head - posterior surface of the humerus (superior to radial groove). Insertion: Olecranon of ulna and fascia of forearm Action: Extension of the arm at the elbow. Innervation: Radial nerve IV-The muscles of the forearm The forearm is the section of the upper limb from the elbow to the wrist. Two muscular compartments - an anterior (flexor) and posterior (extensor) compartment - contain together twenty muscles that act on the elbow and wrist joints, as well as the joints of the hand. IV.1 the Anterior Compartment The flexors of the forearm are located in the anterior compartment of the forearm. Their main functions include flexion of the hand and pronation of the forearm. They are divided into: Superficial: flexor carpi ulnaris, palmaris longus, flexor carpi radialis, pronator teres. Intermediate: flexor digitorum superficialis. Deep: flexor pollicis longus, flexor digitorum profundus and pronator quadratus. IV.1.1 The superficial Compartment Flexor Carpi Ulnaris Flexor carpi ulnaris is a superficial flexor muscle of the forearm that flexes and adducts the hand. It is the most powerful wrist flexor. Origin: Medial epicondyle of humerus, olecranon and posterior border of ulna Insertion: he pisiform bone, hook of hamate, and base of the 5th metacarpal Action: Wrist flexion, wrist adduction Innervation: Ulnar nerve IV.1.2 The superficial Compartment Palmaris Longus The palmaris longus is a small, fusiform-shaped muscle located on the anterior forearm. This muscle is absent in about 15% of the population. Origin: Medial epicondyle of humerus Insertion: Flexor retinaculum, palmar aponeurosis Action: Flexion at the wrist. Innervation: Median nerve IV.1.3 The superficial Compartment Flexor Carpi Radialis Flexor carpi radialis is a fusiform muscle located in the anterior forearm Origin: Medial epicondyle of humerus Insertion: Bases of metacarpal bones 2-3 Action: flexion and abduction of the wrist Innervation: Median nerve. IV.1.4 The superficial Compartment Pronator Teres Pronator teres is the most lateral muscle of the anterior compartment. Origin: Humeral head: medial supracondylar ridge of humerus, Ulnar head: Coronoid process of ulna. Insertion: Lateral surface of radius Action: Pronation of the forearm Innervation: Median nerve IV.1.5 The Intermediate Compartment: flexor digitorum superficialis The flexor digitorum superficialis is the only muscle of the intermediate compartment. Origin: It has two heads – one originates from the medial epicondyle of the humerus, the other from the radius. Insertion: Sides of middle phalanges of digits 2-5. Action: Flexes the metacarpophalangeal joints and proximal interphalangeal joints at the 4 fingers, and flexes at the wrist. Innervation: Median nerve. IV.1.6 Deep Compartment Flexor Digitorum Profundus The Flexor digitorum profundus is situated on the ulnar side of the forearm, immediately beneath the superficial Flexors Origin: Originates from the ulna and associated interosseous membrane Insertion: the distal phalanges of the four fingers 2-5 Action: flexion of the distal and proximal interphalangeal joints of the fingers. It also flexes at metacarpophalangeal joints and at the wrist. Innervation: he medial half: ulnar nerve. The lateral half: median nerve. IV.1.7 Deep Compartment Flexor Pollicis Longus The flexor pollicis longus muscle is one of the three deep flexors of the volar compartment of the forearm. Origin: Anterior surface of radius and interosseous membrane Insertion: Palmar surface of distal phalanx of thumb Action: Flexes the interphalangeal joint and metacarpophalangeal joint of the thumb. Innervation: Median nerve IV.1.8 Deep Compartment Pronator Quadratus The pronator quadratus is a quadrangular, thin, short and flat muscle. Origin: Distal anterior surface of ulna. Insertion: Distal anterior surface of radius. Action: Pronates the forearm. Innervation: Median nerve IV.2 the Posterior Compartment The muscles of the posterior compartment of the forearm produce wrist and/or finger extension and thumb abduction. They are all innervated by the radial nerve. The superficial layer of the posterior forearm contains seven muscles (Brachioradialis, extensor carpi radialis longus, extensor carpi radialis brevis, extensor carpi ulnaris, extensor digitorum, extensor digiti minimi, anconeus) There are five muscles in the deep compartment of the posterior forearm – the supinator, abductor pollicis longus, extensor pollicis brevis, extensor pollicis longus and extensor indicis. IV.2.1 Superficial layer: Brachioradialis The brachioradialis muscle is the most superficial muscle on the radial side of the forearm. Origin: Lateral supracondylar ridge of humerus Insertion: Proximal to styloid process of radius Action: Forearm flexion IV.2.2 Superficial layer: Extensor Carpi Radialis Longus and brevis Extensor carpi radialis longus Origin: Lateral supracondylar ridge of humerus Insertion: Lateral supracondylar ridge of humerus Actions: Extends and abducts the wrist. Extensor carpi radialis brevis Origin: Lateral epicondyle of humerus Insertion: Posterior aspect of base of metacarpal bone 3 Action: Extends and abducts the wrist. IV.2.3 Superficial layer: Extensor Digitorum Communis The extensor digitorum is the main extensor of the fingers. Origin: Lateral epicondyle of humerus. Insertion: the extensor hood of each finger 2-5 Action: Extension of the digits at the interphalangeal and metacarpophalangeal joints. IV.2.4 Superficial layer: Extensor Digiti Minimi The extensor digiti minimi is thought to originate from the extensor digitorum muscle. Origin: Lateral epicondyle of the humerus. Insertion: into the extensor hood of the little finger. Action: Extends the little finger. IV.2.5 Superficial layer: Extensor Carpi Ulnaris The extensor carpi ulnaris is located on the medial aspect of the posterior forearm. Origin: Lateral epicondyle of humerus. Insertion: base of metacarpal V Action: Extension and adduction of wrist. IV.2.6 Superficial layer: Anconeus The anconeus is a small muscle located at the elbow attaching the humerus and ulna. Origin: Lateral epicondyle of humerus Insertion: Lateral surface of olecranon Action: Abducts the ulna during pronation, Extends and stabilises the elbow joint. IV.2.7 Deep compartment: Supinator The supinator has two heads, which the deep branch of the radial nerve passes between. Origin: It has two heads of origin. One originates from the lateral epicondyle of the humerus, the other from the posterior surface of the ulna. Insertion: Lateral, posterior, and anterior surfaces of proximal third of radius Action: Supination of the forearm IV.2.8 Deep compartment: Abductor Pollicis Longus Origin: Posterior surface of proximal half of radius, ulna and interosseus membrane Insertion: Base of metacarpal bone 1 Action: Abducts the thumb. IV.2.9 Deep compartment: Extensor Pollicis Brevis and longus Extensor Pollicis Brevis Origin: Posterior surface of distal third of radius and interosseus membrane Insertion: Base of proximal phalanx of thumb Action: extension of the metacarpophalangeal and carpometacarpal joints of the thumb. Extensor Pollicis longus Origin: Posterior surface of middle third of ulna and interosseus membrane Insertion: distal phalanx of the thumb. Action: Extends all joints of the thumb IV.2.10 Deep compartment: Extensor Indicis Proprius This muscle allows the index finger to be independent of the other fingers during extension Origin: posterior surface of the ulna and interosseous membrane Insertion: the extensor hood of the index finger. Action: Extends the index finger V. The muscles of the hand The skeletal muscles of the hand are responsible for the movement of the hand and fingers. These muscles subdivide into two groups: the extrinsic and intrinsic muscles. Extrinsic muscles located in the forearm Intrinsic muscles – located within the hand itself Four muscle groups comprise the intrinsic hand. These are the thenar, hypothenar, interossei and the lumbrical muscles. V.1 The muscles of the hand: Thenar Muscles The thenar muscles are three short muscles located at the base of the thumb, making a bulge called the thenar eminence. the median nerve innervates all the thenar muscles. Opponens Pollicis: Opposes the thumb. Abductor Pollicis Brevis: Abducts the thumb Flexor Pollicis Brevis: Flexes the metacarpophalangeal joint of the thumb. V.2 The muscles of the hand: Hypothenar Muscles The hypothenar eminence is made up of three muscles; it is located at the base of the fifth digit (little finger). the ulnar nerve innervates all the hypothenar muscles. Opponens Digiti Minimi: finger lateral rotation and opposition Flexor Digiti Minimi Brevis: Flexion of the metacarpophalangeal joint of the little finger. Abductor Digiti Minimi: Abducts the little finger. V.3 The muscles of the hand: Interossei The interossei muscles are located between the metacarpals. They can be divided into two groups: dorsal and palmar. Dorsal Interossei: Abduction of the digits, Assists in flexion at the metacarpophalangeal joints and extension at the interphalangeal joints. Innervation: ulnar nerve Palmar Interossei: Adduction of the digits. Assists in flexion at the metacarpophalangeal joints and extension at the interphalangeal joints. Innervation ulnar nerve. V.4 The muscles of the hand: Lumbricals The lumbrical muscles of the hand are a group of four muscles. All four lumbricals flex their respective metacarpophalangeal joint and extend the proximal interphalangeal and distal interphalangeal joints. The lateral two lumbricals (of the index and middle fingers) are innervated by the median nerve. The medial two lumbricals (of the little and ring fingers) are innervated by the ulnar nerve. There are two other muscles in the palm that are not V.5 The muscles of lumbricals or interossei and do not fit in the hypothenar or thenar compartments: palmaris brevis: Tightens palmar aponeurosis the hand: other Adductor Pollicis: Adductor of the thumb muscles Innervation: Ulnar nerve D- Blood Vessels, Lymphatics and nerves of the Upper Limb The systemic circulation in the human body divides into the arterial blood supply and the venous drainage. These two circulations are linked together by the capillary beds. The arterial blood supply is responsible for perfusing the body with oxygenated and nutrient-rich blood, while the venous blood drainage is responsible for draining the deoxygenated blood and metabolic waste. The lymphatic system functions to drain tissue fluid, plasma proteins and other cellular debris and immune defence.. I- arterial supply to the upper limb The arterial supply to the upper limb is delivered via five main vessels (proximal to distal): Subclavian artery, Axillary artery, Brachial artery, Radial artery, Ulnar artery. The subclavian artery: On the right, the subclavian artery arises from the brachiocephalic trunk. On the left, it branches directly from the arch of aorta. The subclavian artery travels laterally towards the axilla. At the lateral border of the first rib, the subclavian artery enters the axilla – and is renamed the axillary artery. I- arterial supply to the upper limb The axillary artery is a continuation of the subclavian artery that begins at the outer border of the first rib. It then courses through the axilla, and at the lower border of the teres major muscle, the axillary artery is renamed the brachial artery. It has six branches: Superior Thoracic Artery, Thoracoacromial Artery, Lateral Thoracic Artery, Subscapular Artery, Anterior Circumflex Humeral Artery, Posterior Circumflex Humeral Artery I- arterial supply to the upper limb The brachial artery is a continuation of the axillary artery past the lower border of the teres major. it ends at the level of the neck of the radius about 1cm distal to the The cubital fossa. At this point, it divides into the ulnar and radial arteries. The brachial artery runs medial to the humerus proximally, before moving more anteriorly to lie between the epicondyles of the humerus. I- arterial supply to the upper limb The radial artery begins at the inferior portion of the cubital fossa after it has bifurcated from the brachial artery. It supplies the lateral aspect of the forearm. It contributes to anastomotic networks surrounding the elbow joint and carpal bones. At the wrist, the radial artery goes around it laterally and then travels across the floor of the anatomical snuffbox to the palm of the hand. The ulnar artery arises in the cubital fossa and traverses through the medial (ulnar) side of the forearm and ends within the medial portion of the hand as the superficial palmar arch. The ulnar artery gives off the common interosseus artery which then divides to give the anterior and posterior interosseous arteries. I- arterial supply to the upper limb Arterial supply to the hand begins with the ulnar and radial arteries. The ulnar artery enters the hand anteriorly to the flexor retinaculum and laterally to the ulnar nerve. The radial artery enters the hand dorsally, crossing the floor of the anatomical snuffbox. As a result, two arterial arches are formed: Superficial palmar arch – located anteriorly to the flexor tendons in the hand and deep to the palmar aponeurosis. It gives rise to the digital arteries, which supply the four fingers. Deep palmar arch – located deep to the flexor tendons of the hand. It contributes to the blood supply to the digits and to the wrist joint. II- Venous Drainage of the Upper Limb. Veins of the upper limb are divided into superficial and deep veins. Superficial Veins: They are located within the subcutaneous tissue of the upper limb. The cephalic vein arises from the radial aspect of the dorsal venous network. It ascends the antero-lateral aspect of the upper limb, passing anteriorly at the elbow. At the shoulder, the cephalic vein travels between the deltoid and pectoralis major muscles, and enters the axilla region where the cephalic vein empties into axillary vein. the basilic vein arises from the dorsal venous network of the hand and ascends the medial aspect of the upper limb. At the border of the teres major, the vein moves deep into the arm. Here, it combines with the brachial veins from the deep venous system to form the axillary vein. II- Venous Drainage of the Upper Limb Deep Veins The radial and ulnar veins are the main deep veins of the forearm. They are typically made up of two veins each which accompany the radial and ulnar arteries. The brachial veins are the largest in size and are situated either side of the brachial artery. Perforating veins run between the deep and superficial veins. E- Anatomical Areas There are 8 areas covered in the upper limb: The axilla, the quadrangular space, the triangular space, the triangular interval cubital fossa, ulnar (Guyon’s) canal, carpal tunnel and anatomical snuffbox. I- The axilla region The axilla is an anatomical region under the shoulder joint where the arm connects to the shoulder. It contains a variety of neurovascular structures, including the axillary artery, axillary vein, brachial plexus, and lymph nodes Biceps brachii (short head) and coracobrachialis There are five anatomic borders of the axilla: the superior, anterior, posterior, lateral, and medial walls Lateral wall formed by intertubercular groove of the humerus, Medial wall consists of the serratus anterior and the thoracic wall Anterior wall contains the pectoralis major, pectoralis minor and the subclavius muscles. Posterior wall formed by the subscapularis, teres major and latissimus dorsi. The Quadrangular Space The quadrangular space is an anatomical space is the posterior axilla region. It provides a conduit for structures to pass between the axilla and the posterior compartment of the arm. The quadrangular space is rectangular-shaped with four boundaries: Superior – inferior margin of teres minor. Lateral – surgical neck of the humerus. Medial – long head of triceps brachii. Inferior – superior aspect of teres major. It contains the axillary nerve and posterior circumflex humeral artery (and accompanying vein) as they travel into the posterior upper arm. By Triangular Space The triangular space is an anatomical space located in the axilla. It is orientated with the base laterally and apex medially. It has three borders: Lateral – medial margin of the long head of the triceps brachii. Inferior – superior margin of the teres major. Superior – inferior border of the teres minor (or subscapularis). It contains the circumflex scapular artery and vein. The Triangular Interval The triangular interval is an anatomical space located immediately below the axilla region. The triangular interval is orientated with the base superiorly and apex inferiorly. It has three borders: Superior – Inferior border of the teres major. Lateral – Shaft of the humerus and lateral head of the triceps brachii. Medial – Lateral border of the long head of the triceps brachii. It contains the radial nerve and profunda brachii artery (and accompanying vena comitantes) II- The cubital fossa The cubital fossa is a small triangular area located on the anterior surface of the elbow, with the apex of the triangle pointing distally. The cubital fossa contains four structures (from medial to lateral): Median nerve, Brachial artery, Tendon of biceps brachii, Radial nerve. The cubital fossa is triangular and consists of three borders, a roof, and a floor: Lateral border – medial border of the brachioradialis muscle. Medial border – lateral border of the pronator teres muscle. Superior border – horizontal line drawn between the epicondyles of the humerus. Roof – bicipital aponeurosis, fascia, subcutaneous fat and skin. Floor – brachialis (proximally) and supinator (distally). III- Carpal tunnel The carpal tunnel is a narrow osteofibrous canal located on the palmar side of the wrist, it serves as the entrance to the palm for several tendons and the median nerve. The boundaries are the carpal bones forming the floor, and the flexor retinaculum (or transverse carpal ligament) forming the roof. It contains: The tendon of flexor pollicis longus, Four tendons of flexor digitorum profundus, Four tendons of flexor digitorum superficialis and the median nerve. IV- The anatomical snuffbox The anatomical snuffbox is a surface anatomy feature described as a triangular depression on the dorsum of the hand at the base of the thumb. It is located at the level of the carpal bones In the past, this depression was used to hold snuff (ground tobacco) before inhaling via the nose , and best seen when the thumb is extended. Contents: Radial artery, Superficial branch of the radial nerve, Cephalic vein. Borders: Tendon of the extensor pollicis longus (Ulnar border), Tendons of the extensor pollicis brevis and abductor pollicis longus (Radial border), Styloid process of the radius (Proximal border), Carpal bones; scaphoid and trapezium (Floor), Skin (Roof). V- Ulnar (Guyon’s) canal The ulnar (Guyon’s) canal is a fibro- osseous tunnel located at the level of the palm. It transmits the ulnar neurovascular bundle from the forearm into the hand. Contents: Ulnar nerve, Ulnar artery, Venae comitantes of ulnar artery Borders: pisiform, flexor carpi ulnaris tendon, abductor digiti minimi muscle (medial), hook of hamate (lateral), palmar carpal ligament (roof), transverse carpal ligament (floor) F- Surface anatomy Gray's Anatomy for Students REFERENCES Atlas Of Human Anatomy By Frank H. Netter BOOKS

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