Human Anatomy I (CLI 210) PDF

ANATOMICAL TERMINOLOGY Dr. David O. Adeyemi Anatomy and Cell Biology, Obafemi Awolowo University, Ile Ife National Open University of Nigeria National Open Univers...

ANATOMICAL TERMINOLOGY Dr. David O. Adeyemi Anatomy and Cell Biology, Obafemi Awolowo University, Ile Ife National Open University of Nigeria National Open University Of Nigeria  Objectives By the end of this section, you will be able to: Demonstrate the anatomical position Describe the human body using directional and regional terms Identify three planes most commonly used in the study of anatomy  Introduction language of anatomy Anatomists and health care providers use terminology that can be bewildering to the uninitiated. However, the purpose of this language is not to confuse, but rather to increase precision and reduce medical errors Anatomical Position To avoid ambiguity, all anatomical descriptions are expressed in relation to one consistent anatomical position. The anatomical position is that of a body standing upright and facing forwards, upper limbs by the side with the palms facing forwards, and lower limbs together with the toes directed forwards Anatomical Planes Anatomical descriptions are based on four imaginary planes that intersect the body in the anatomical position. ✓ median, ✓ sagittal, ✓ coronal, and ✓ transverse  Anatomical Planes The median (mid saggital) plane, the vertical plane passing longitudinally through the body, divides the body into right and left halves. Sagittal planes are vertical planes passing through the body parallel to the median plane. Coronal (Frontal) planes are vertical planes passing through the body at right angles to the median plane, dividing the body into anterior (front) and posterior (back) parts Transverse planes are planes passing through the body at right angles to the median and frontal planes, dividing the body into superior (upper) and inferior (lower) parts. Terms of Relationship & Comparison describes the relationship of parts of the body in the anatomical position and compare the position of two structures relative to each other - superior (cranial) & inferior(caudal) - anterior (ventral) & posterior (dosal) - medial & lateral - proximal & distal - superficial & deep - Combined terms such as Terms of Relationship & Comparison  Describe the relationship of the nose relative to eyes Describe the relationship of the knee to relative to the ankle Class Activity I Regional Terms Regional terms describe the different parts of the body by structures and functions of a specific region Basic regional terms are axial and appendicular regions Different parts of these regions can be described by terms such as - cranial, facial, nuchal - cervical - pectoral, sternal, scapular acromial - thoracic - abdominal, lumbar, inguinal - brachial, antebrachial, carpal, - femoral, popliteal, crural, tarsal, - dorsum planta, palmar - gluteal, pubic, pelvic, perineal Terms of Movement Anatomical terms of movement are used to describe the actions of muscles on skeleton. Muscle contract to produce movement at the joint and the subsequent movement can be precisely described using this terminology flexion – extension Adduction – Abduction circumduction medial & lateral rotation plantaflexion and dorsiflexion elevation & depression pronation & supination Inversion and eversion protrusion & retrusion Terms of Movement  What movements are involved in standing from a sitting position What kind of movement is involved in lifting a load onto Class Activity II your head from the floor  HUMAN ANATOMY I (CLI 210) (4 Unit) ‘WALE ADEYEMI ANATOMY AND CELL BIOLOGY FACULTY OF BASIC MEDICAL SCIENCES TOPIC: AXILLA  INTRODUCTION TO CONTENT ▪ Definition ✓ Location ✓Boundaries ✓Function ▪ Features (Apex ,Base, Wall) ▪ Contents ▪ Applied Anatomy  INTRODUCTION ▪ The axilla (arm pit )is a junctional region where nerves and vessels coming from the neck region passes through to the upper limb.  INTRODUCTION ▪ The axilla (arm pit) is described as a truncated 3-sided pyramidal space between the upper most part of the medial side of the arm and the upper part of the lateral wall of the thorax. ▪ It lies inferior to the shoulder (glenohumeral) joint and superior to the axillary fascia at the junction of the arm and the thorax. ▪ The axilla provides a passage way for vessels and nerves coming from the root of the neck to reach the upper limbs.  General description Longitudinal Transverse  Features an apex, The axilla a has 4 base walls.  APEX ▪ The apex of the axilla lies medial to the coracoid process ▪ it continues into the root of the neck (cervicoaxillary canal). ▪ It is triangular in shape and is formed by outer border of the first rib medially, superior border of the scapula posteriorly and the posterior surface of the clavicle anteriorily.  APEX Scapula (posterior border) 1st rib (medial border) Manubrium Clavicle (anterior border)  APEX ▪ The arteries veins, lymphatics and nerves coming from the neck enters the axilla through the apex.  BASE ▪ The base of the axilla faces downwards ▪ It is formed by the skin and a thick layer of axillary (deep) fascia extending from the arm to the thoracic wall (between the inferior borders of pectoralis major in front and latissimus dorsi behind).  WALL ▪ Anterior Wall – is formed by the pectoralis major and minor and the pectoral and clavipectoral fascia associated with them. ▪ Posterior Wall – is chiefly formed above by the scapula and the subscapularis muscle on its anterior surface and below by teres major and latissimus dorsi. WALL  WALL ▪ Medial Wall – this wall is convex laterally and is formed by the first 4 ribs with their intercostal muscles and the upper four digitations of the serratus anterior muscle. ▪ Lateral Wall – is a narrow bony wall formed by the intertubercular groove of the humerus and the conjoint upper part of the coracobrachialis and short head of biceps.  CONTENTS OF THE AXILLA ▪ axillary artery and its branches ▪ axillary vein and its tributaries ▪ the three cords of brachial plexus ▪ axillary lymph nodes and vessels ▪ lateral branches of upper intercostals vessels ▪ loose adipose (areola) tissue CONTENTS OF THE AXILLA  Summary ▪ The axilla is a junctional region in the upper limb ▪ It lies between the upper part of the upper part of the arm and the upper part of the side of the thoracic wall ▪ It allows the passage of the neurovascular bundles supplying the upper limbs from the cervical region.  HUMAN ANATOMY I (CLI 213) (4 Unit) ‘WALE ADEYEMI ANATOMY AND CELL BIOLOGY FACULTY OF BASIC MEDICAL SCIENCES 1 Topic OSTEOLOGY OF THE UPPER LIMBS 2  Introduction ▪ Osteology is the study of bones ▪ Upper limbs can be divided into 4 segments – ✓Pectoral girdle ( scapula & clavicle) ✓Arm (humerus) ✓Fore arm (radius & ulna) ✓Hand (carpals, metacarpals, phalanges) 3 4 5 6 THE HUMERUS 7 INTRODUCTION ▪ The humerus is the largest bone in the upper limb. ▪ It articulate with the glenoid cavity of the scapula at the glenohumeral joint and with the radius and ulna at the elbow joint. ▪ It has ✓a proximal end, ✓shaft (body) and ✓distal end. 8 9 10 The proximal end ▪ The proximal end of the humerus has a head, a neck and greater and lesser tubercules. ▪ The ball shaped head of the humerus articulate with the glenoid cavity of scapula. ▪ The anatomical neck of the humerus is formed by a groove circumscribing the head and separating if from greater and lesser tubercle (tuberocities). 11 The proximal end ▪ The greater tubercle is at the lateral margin of the humerus while the lesser tubercle project anteriorly. ▪ The intertubercular grooves (bicipital groove) separate the tubercles. ▪ The surgical neck of the humerus is the narrow part distal to the tubercles. ▪ The surgical neck is a common fracture site of the humerus. 12 Greater & Lesser tubercles ▪ Greater tubercle ✓ It is the most lateral part of the proximal end of humerus. ✓ Its posterosuperior aspect bears three flattened facet-like impressions: upper, middle and lower which provide ✓ attachment to supraspinatus, infraspinatus and teres minor muscles respectively. ▪ Lesser tubercle ✓ It is small elevation on the front of upper end of humerus, just above the surgical neck. ✓ It provides attachment to subscapularis muscle 13 Intertubercular Sulcus/Bicipital Groove ✓It is a vertical groove between lesser and greater tubercles. ✓It contains: ❖long head of biceps, enclosed in the synovial sheath, and ❖ascending branch of anterior circumflex humeral artery. ✓Three muscles are attached in the region of this groove: ❖Pectoralis major on the outer lip of the groove. ❖Teres major on the inner lip of the groove. ❖Latissimus dorsi in the floor of the groove. 14 15 The Shaft ▪ The body of humerus (shaft) has two prominent features: ✓The deltoid tuberosity laterally for attachment of deltoid muscle, and ✓the oblique radial groove, posteriorly in which the radial nerve and deep artery of the arm lie. 16 The distal end ▪ The inferior (distal) end of the humerus widens as the sharp, medial and lateral supracondylar ridges which ends inferiorly as the medial and lateral epicondlyles. ▪ The inferior end (condyle) of the humerus has 2 articular surfaces: ✓A lateral capitulum for articulation with the head of radius and ✓A medial trochlea for articulation with the trochlea notch of the ulna 17 Distal end 18 The distal end ▪ Superior to the trochlea anteriorly is the coronoid fossa which receives the coronoid process of ulna during full flexion of elbow, and ▪ posteriorly is the olecranon fossa which accommodate the olecranon of the ulna during full extension of the elbow. ▪ Superior to the capitulum anteriorly is a shallow radial fossa which accommodates the edge of the head of radius when the forearm is fully flexed. 19 Applied Anatomy ▪ Fracture of the humerus:– The most common sites of humeral fracture are surgical neck, shaft and supracondylar regions. ▪ The following part of the humerus are in direct contact with the structure indicated below. ▪ Surgical neck – axillary nerve, anterior and posterior circumflex humeral artery. ▪ Radial groove – radial nerve, profunda brachial artery ▪ Distal end of humerus – median nerve ▪ Medial epicondyle – ulnar nerve ▪ These nerves and vessel may be injured when the associated part of the humerus is fractured. 20 THE ULNA 21 INTRODUCTION ▪ The ulna is the medial and longer of the two forearm bones. ▪ It articulate with the trochlea of the humerus at the elbow joint and with the radius at the proximal and distal radioulna joint. ▪ It has ✓a proximal end, ✓shaft (body) and ✓distal end. 22 23 proximal end ▪ Its proximal end has two prominent projections; ✓The olecranon which project proximally from its posterior aspect and ✓the coronoid process which project anteriorly. ▪ On the anterior surface of the olecranon is a notch, trochlea notch which articulate with the trochlea of humerus. 24 proximal end ▪ On the lateral side of coronoid process is the radial notch which articulate with the head of radius. ▪ Inferior to the coronoid process is the tuberosity of ulna for attachment of the tendon of brachialis muscle. 25 Body and inferior end ▪ The body of ulna is thick and cylindrical proximally, but it tapers, diminishing in diameter as it continues distally. ▪ At its narrow distal end is a somewhat abrupt enlargement forming a disc like head and a small conical styloid process. 26 THE RADIUS 27 The radius ▪ The radius is the lateral and shorter of the two forearm bones. ▪ Its proximal end consists of a short cylindrical head, a neck and a medially directed radial tuberosity. ▪ The smooth superior aspect of the head of radius is concave for articulation with the capitulum of humerus. ▪ The body of the radius has a lateral convexity. It gradually and progressively enlarges in girth (width) as it passes distally. 28 The radius ▪ The distal end of the radius is essentially rectangular when sectioned transversely. ▪ Its medial aspect form a concavity, the ulna notch which accommodates the head of ulna. ▪ Extending from its lateral aspect is the radial styloid process 29 BONES OF THE HAND 30 CARPUS ▪ The skeleton of the wrist (carpus) is composed of 8 carpal bones arranged in two rows of four each. These bones give flexibility to the wrist. ▪ From lateral to medial, the 4 bones in the proximal row of carpals are ✓scaphoid (boat shaped), ✓Lunate (moon shaped), ✓triquetrum (pyramidal bone) and ✓pisiform (pea shaped bone lying on the palmer surface of triquetrium). 31 CARPUS ▪ From the lateral to medial, the four bones in the distal row of carpal are ✓trapezium, ✓trapezoid, ✓capitate and ✓hamate. ❖The hamate has a hook-like process called hook of hamate. 32 METACARPALS and PHALANGES ▪ The skeleton of the hand between the carpus and phalanges _ (metacarpus) – is composed of 5 metacarpal bones. Each metacarpal consist of a body and two ends. ▪ Each digit has 3 phalanges except the first digit (thumb) which has only 2. 33  PECTORAL GIRDLE AND ITS ASSOCIATED JOINTS Dr. D.O. Adeyemi Anatomy and Cell Biology 1  INTRODUCTION  The pectoral girdle or shoulder girdle is the set of bones which connects the upper limb to the axial skeleton on each side.  It consists of the clavicle and scapula in humans 2 INTRODUCTION 3  INTRODUCTION  The superior appendicular skeleton articulates with the axial skeleton only at the sternoclavicular joint, allowing great mobility.  The clavicles and scapulae of the pectoral girdle are supported, stabilized, and moved by axioappendicular muscles (AAPM) 4  INTRODUCTION  AAPM attach to the relatively fixed ribs, sternum, and vertebrae of the axial skeleton. 5  CLAVICLE  The clavicle (collar bone) connects the upper limb to the trunk.  The shaft of the clavicle has a double curve in a horizontal plane.  Its medial half is convex anteriorly while Its lateral half is concave anteriorly 6  CLAVICLE  Its sternal end is enlarged and triangular where it articulates with the manubrium of the sternum at the sternoclavicular (SC) joint.  its acromial end is flat where it articulates with the acromion of the scapula at the acromioclavicular (AC) joint 7 CLAVICLE 8  CLAVICLE - functions  The clavicle Serves as a moveable, rigid support (strut) from which the scapula and free limb are suspended,  The clavicle forms one of the bony boundaries of the cervicoaxillary canal  It also transmits shocks from the upper limb to the axial skeleton 9  CLAVICLE - Structure  Although designated as a long bone, the clavicle has no medullary (marrow) cavity. It consists of spongy (trabecular) bone with a shell of compact bone. 10  CLAVICLE - Features  The superior surface of the clavicle is smooth. 11  CLAVICLE - Features  The inferior surface of the clavicle is rough because strong ligaments bind it to the 1st rib near its sternal end and suspend the scapula from its acromial end.  The conoid tubercle gives attachment to the conoid ligament,  The trapezoid line gives attachment to the trapezoid ligament.  The subclavian groove in the medial third of the shaft of the clavicle is the site of attachment of the subclavius muscle.  More medially is the impression for the costoclavicular ligament, 12 CLAVICLE - Features 13  CLAVICLE – Clinical correlates  Fracture of the Clavicle  The clavicle is one of the most frequently fractured bones in children  Most common site of fracture is the junction of its middle and lateral thirds  After fracture, the sternocleidomastoid elevates the medial fragment of bone  The trapezius muscle is unable to hold the lateral fragment up owing to the weight of the upper limb, and thus the shoulder drops 14  The two fragment overlaps and the bone shortens  CLAVICLE – Clinical correlates  Ossification of the Clavicle  The clavicle is the first long bone to ossify via intramembranous ossification  Ossification begin during the 5th and 6th embryonic weeks from medial and lateral primary centers that are close together in the shaft of the clavicle  The ends of the clavicle later pass through a cartilaginous phase (endochondral ossification) 15  CLAVICLE – Clinical correlates  Ossification of the Clavicle A secondary ossification center appears at the sternal end  forms a scale-like epiphysis that begins to fuse with the shaft (diaphysis) between 18 and 25 years of age  is completely fused to it between 25 and 31 years of age.  Making it to be the last of the epiphyses of long bones to fuse. 16 17  SCAPULA  The scapula (shoulder blade) is a triangular flat bone that lies on the posterolateral aspect of the thorax, overlying the 2nd - 7th ribs 18  SCAPULA - features  Two surfaces – anterior (coastal) & posterior  Three borders – medial, lateral and superior  Three angles – superior, lateral & inferior  Three processes- spine, acromion and coracoid 19 SCAPULA - features 20  SCAPULA - features  The convex posterior surface of the scapula is unevenly divided by a thick shelf–like ridge of bone, the spine, into two a small supraspinous fossa and a much larger infraspinous fossa  The concave costal surface forms a large subscapular fossa 21  SCAPULA - featurese  The convex posterior surface of the scapula is unevenly divided by a thick shelf–like ridge of bone, the spine, into two a small supraspinous fossa and a much larger infraspinous fossa  The concave costal surface forms a large subscapular fossa 22  SCAPULA - features  scapula is thin and translucent superior and inferior to the scapular spine; although its borders, especially the lateral one, are somewhat thicker. 23  SCAPULA - features  The spine continues laterally as the flat expanded acromion which forms the subcutaneous point of the shoulder and articulates with the acromial end of the clavicle.  The deltoid tubercle of the scapular spine is the prominence indicating the medial point of attachment of the deltoid.  The spine and acromion serve as levers for the attached muscles, particularly the trapezius. 24  SCAPULA - features  Superolaterally, the lateral border of the scapula has a glenoid cavity which receives and articulates with the head of the humerus at the glenohumeral joint  superior to the glenoid cavity, the coracoid process projects anterolaterally 25  SCAPULA - features  When the scapular body is in the anatomical position, the thin medial border of the scapula runs parallel (lateral) to the spinous processes of the thoracic vertebrae hence name the vertebra border.  From the inferior angle, the lateral border of the scapula runs superolaterally toward the apex of the axilla; hence name the axillary border. 26  SCAPULA - features  The lateral border is the thickest part of the bone that bears the broadened head of the scapula.  The shallow constriction between the head and the body defines the neck of the scapula.  The superior border of the scapula is marked near the junction of its medial two thirds and lateral third by the suprascapular notch, 27  SCAPULA - features  superior border is the thinnest and shortest of the three borders  The scapula is capable of considerable movement on the thoracic wall at the physiological scapulothoracic joint, providing the base from which the upper limb operates. 28 SCAPULA - Muscular attachments 29 SCAPULA – Muscular attachments 30 ASSOCIATED JOINTS OF THE PECTORAL GIRDLE Dr. D.O. Adeyemi Anatomy and Cell Biology 31 Sternoclavicular Joint  The sternoclavicular joint is a saddle type of synovial joint but functions as a ball-and-socket joint.  The SC joint is divided into two compartments by an articular disc.  The disc is firmly attached to the anterior and posterior sternoclavicular ligaments as well as the interclavicular ligament 32 Sternoclavicular Joint  The SC joint is the only articulation between the upper limb and the axial skeleton,  it can be readily palpated because the sternal end of the clavicle lies superior to the manubrium of the sternum. 33 Sternoclavicular Joint  Articulation  The sternal end of the clavicle articulates with the manubrium and the 1st costal cartilage.  The articular surfaces are covered with fibrocartilage 34 Sternoclavicular Joint  Joint Capsule  The joint capsule surrounds the SC joint, including the epiphysis at the sternal end of the clavicle.  It is attached to the margins of the articular surfaces, including the periphery of the articular disc. A synovial membrane lines the internal surface of the fibrous layer of the joint capsule, extending to the edges of the articular surfaces. 35 Sternoclavicular Joint  Ligaments  Anterior and posterior sternoclavicular ligaments reinforce the joint capsule anteriorly and posteriorly  The interclavicular ligament strengthens the capsule superiorly  costoclavicular ligament anchors the inferior surface of the sternal end of the clavicle to the 1st rib and its costal cartilage 36 Sternoclavicular Joint  Movements  Allows elevation and depression movement  Rotation 37 Sternoclavicular Joint  Blood Supply  The SC joint is supplied by internal thoracic and suprascapular arteries  Nerve Supply  Branches of the medial supraclavicular nerve and the nerve to the subclavius supply the SC joint 38 Acromioclavicular Joint  The acromioclavicular joint (AC joint) is a plane type of synovial joint, which is located 2-3 cm from the point of the shoulder formed by the lateral part of the acromion 39 Acromioclavicular Joint  Articulation  The acromial end of the clavicle articulates with the acromion of the scapula.  The articular surfaces, covered with fibrocartilage and are separated by an incomplete wedge-shaped articular disc 40 Acromioclavicular Joint  Joint Capsule  The fibrous layer of the joint capsule is attached to the margins of the articular surfaces  A synovial membrane lines the fibrous layer.  Although relatively weak, the joint capsule is strengthened superiorly by fibers of the trapezius. 41 Acromioclavicular Joint  Ligaments  The acromioclavicular ligament strengthens the AC joint superiorly  The coracoclavicular ligament is an extrinsic ligament that unite the coracoid process of the scapula to the clavicle and augument the strengthening of the joint 42 43 Acromioclavicular Joint  Movements  The acromion of the scapula rotates on the acromial end of the clavicle  These movements are associated with motion at the physiological scapulothoracic joint 44 Acromioclavicular Joint  Blood Supply  The AC joint is supplied by the suprascapular and thoracoacromial arteries  Nerve Supply  the lateral pectoral and axillary nerves supply the AC joint  lateral supraclavicular nerve 45 PECTORAL REGION AND THE SHOULDER JOINT Dr. D.O. Adeyemi Anatomy and Cell Biology INTRODUCTION  Anterior Axioappendicular Muscles of the Upper Limb  The posterior axioappendicular muscles and Scapulohumeral Muscles Anterior Axioappendicular Muscles INTRODUCTION  Four anterior axioappendicular (pectoral or thoracoappendicular) muscles move the pectoral girdle:  pectoralis major,  pectoralis minor,  subclavius, and  serratus anterior. PECTORALIS MAJOR  The pectoralis major is a large, fan-shaped muscle that covers the superior part of the thorax.  It has clavicular and sternocostal heads.  The sternocostal head is much larger and its lateral border forms the anterior wall of the axilla.  Its inferior border forms the anterior axillary fold PECTORALIS MAJOR  The pectoralis major and deltoid form the narrow deltopectoral groove, in which the cephalic vein runs  the muscles, however, diverge slightly from each other superiorly and, along with the clavicle, form the clavipectoral (deltopectoral) triangle PECTORALIS MAJOR  Proximal Attachment –  Clavicular head: anterior surface of medial half of clavicle  Sternocostal head: anterior surface of sternum, superior six costal cartilages, aponeurosis of external oblique muscle  Distal Attachment  Lateral lip of intertubercular groove of humerus  Innervation  Lateral and medial pectoral nerves; clavicular head (C5, C6), sternocostal head (C7, C8, T1) PECTORALIS MAJOR  Actions–  Adducts and medially rotates humerus; draws scapula anteriorly and inferiorly  Acting alone, clavicular head flexes humerus and sternocostal head extends it from the flexed position PECTORALIS MINOR  The pectoralis minor is a triangular shaped muscle  lies in the anterior wall of the axilla where it is almost completely covered by the pectoralis major PECTORALIS MINOR  The pectoralis minor is a useful anatomical and surgical landmark for structures in the axilla (e.g., the axillary artery).  With the coracoid process, the pectoralis minor forms a bridge under which vessels and nerves must pass to the arm PECTORALIS MINOR  Proximal Attachment –  3rd - 5th ribs near their costal cartilages  Distal Attachment  Medial border and superior surface of coracoid process of scapula  Innervation  Medial pectoral nerve (C8, T1)  Action  Stabilizes scapula by drawing it inferiorly and anteriorly against thoracic wall  assists in elevating the ribs for deep inspiration when the pectoral girdle is elevated SUBCLAVIUS  The subclavius is a small, round muscle located inferior to the clavicle and affords some protection to the subclavian vessels and the superior trunk of the brachial plexus if the clavicle fractures.  It lies almost horizontally when the arm is in the anatomical position SUBCLAVIUS  Proximal Attachment –  Junction of 1st rib and its costal cartilage  Distal Attachment  Inferior surface of middle third of clavicle  Innervation  Nerve to sub-clavius (C5, C6)  Action  Anchors and depresses the clavicle, stabilizing it during movements of the upper limb. SERRATUS ANTERIOR  The serratus anterior overlies the lateral part of the thorax and forms the medial wall of the axilla.  This broad sheet of thick muscle was named because of the saw toothed appearance of its fleshy slips or digitations SERRATUS ANTERIOR  Proximal Attachment –  External surfaces of lateral parts of 1st - 8th ribs  Distal Attachment  Anterior surface of medial border of scapula  Innervation  Long thoracic nerve (C5, C6, C7)  Action  Protracts scapula and holds it against thoracic wall;  rotates scapula POSTERIOR AXIOAPPENDICULAR AND SCAPULOHUMERAL MUSCLES INTRODUCTION  The posterior shoulder muscles are divided into three groups  Superficial posterior axioappendicular (extrinsic shoulder) muscles: trapezius and latissimus dorsi.  Deep posterior axioappendicular (extrinsic shoulder) muscles: levator scapulae and rhomboids.  Scapulohumeral (intrinsic shoulder) muscles: deltoid, teres major, and the four rotator cuff muscles (supraspinatus, infraspinatus, teres minor, and subscapularis). SUPERFICIAL POSTERIOR AXIOAPPENDICULAR  TRAPEZIUS  The trapezius provides a direct attachment of the pectoral girdle to the trunk.  This large, triangular muscle covers the posterior aspect of the neck and the superior half of the trunk  trapezius attaches the pectoral girdle to the cranium and vertebral column and assists in suspending the upper limb.  TRAPEZIUS  The fibers of the trapezius are divided into three parts,  superior fibers elevate the scapula  middle fibers retract the scapula  inferior fibers depress the scapula and lower the shoulder.  TRAPEZIUS  Proximal Attachment –  Medial third of superior nuchal line; external occipital protuberance; nuchal ligament; spinous processes of C7 - T12 vertebrae  Distal Attachment  Lateral third of clavicle; acromion and spine of scapula  Innervation  Accessory nerve (CN XI) (motor fibers) and  C3, C4 spinal nerves (pain and proprioceptive fibers)  Action  Descending part elevates; ascending part depresses; and middle part (or all parts together) retracts scapula; descending and ascending parts act together to rotate glenoid cavity superiorly  LATISSIMUS DORSI  latissimus dorsi is a fan shaped muscle which covers a wide area of the back  It passes from the trunk to the humerus and acts directly on the glenohumeral joint and indirectly on the pectoral girdle  LATISSIMUS DORSI  Proximal Attachment –  Spinous processes of inferior 6 thoracic vertebrae, thoracolumbar fascia, iliac crest, and inferior 3 or 4 ribs  Distal Attachment  Floor of intertubercular groove of humerus  Innervation  Thoracodorsal nerve (C6, C7, C8)  Action  Extends, adducts, and medially rotates humerus; raises body toward arms during climbing DEEP POSTERIOR AXIOAPPENDICULAR (EXTRINSIC SHOULDER) MUSCLES  LEVATOR SCAPULAE  This strap-like muscle is so named because it elevates the scapula  Its superior third lies deep to the sternocleidomastoid;  the inferior third is deep to the trapezius  LEVATOR SCAPULAE  Proximal Attachment –  Posterior tubercles of transverse processes of C1 - C4 vertebrae  Distal Attachment  Medial border of scapula superior to root of spine  Innervation  Dorsal scapular (C5) and cervical (C3, C4) nerves  Action  Elevates scapula and tilts its glenoid cavity inferiorly by rotating scapula  RHOMBOID MINOR & MAJOR  The rhomboid major and rhomboid minor have a rhomboid appearance  They lie deep to the trapezius and form broad parallel bands that pass inferolaterally from the vertebrae to the medial border of the scapula.  The thin, flat rhomboid major is approximately two times wider than the thicker rhomboid minor lying superior to it. RHOMBOID MINOR & MAJOR  RHOMBOID MINOR  Proximal Attachment –  nuchal ligament; spinous processes of C7 and T1 vertebrae  Distal Attachment  Smooth triangular area at medial end of scapular spine  Innervation  Dorsal scapular (C4, C5)  Action  Retract scapula and rotate it to depress glenoid cavity; fix scapula to thoracic wall  RHOMBOID MAJOR  Proximal Attachment –  spinous processes of T2 - T5 vertebrae  Distal Attachment  medial border of scapula from level of spine to inferior angle  Innervation  Dorsal scapular (C4, C5)  Action  Retract scapula and rotate it to depress glenoid cavity; fix scapula to thoracic wall SCAPULOHUMERAL (INTRINSIC SHOULDER) MUSCLES  DELTOID  The deltoid is a thick, powerful, coarse-textured muscle covering the shoulder and forming its rounded contour  The muscle is divided into  unipennate anterior and posterior parts and a multipennate middle part;  DELTOID  Proximal Attachment –  Lateral third of clavicle; acromion and spine of scapula  Distal Attachment  Deltoid tuberosity of humerus  Innervation  Axillary nerve (C5, C6)  Action  Anterior part: flexes and medially rotates arm  Middle part: abducts arm  Posterior part: extends and laterally rotates arm  TERES MAJOR  The teres major is a thick, rounded muscle that forms a raised oval area on the inferolateral third of the scapula when the arm is adducted against resistance  The inferior border of the teres major forms the inferior border of the lateral part of the posterior wall of the axilla.  TERES MAJOR  Proximal Attachment –  Posterior surface of lateral border of scapula  Distal Attachment  Medial lip of intertubercular groove of humerus  Innervation  Lower subscapular nerve (C5, C6)  Action  Adducts and medially rotates arm  ROTATOR CUFF MUSCLES  Four of the scapulohumeral muscles - supraspinatus, infraspinatus, teres minor, and subscapularis (SITS) are called rotator cuff muscles because they form a musculotendinous rotator cuff around the glenohumeral joint  All except the supraspinatus are rotators of the humerus  ROTATOR CUFF MUSCLES  The supraspinatus occupies the supraspinous fossa of the scapula.  The infraspinatus occupies the medial three quarters of the infraspinous fossa and is partly covered by the deltoid and trapezius.  ROTATOR CUFF MUSCLES  The teres minor is a narrow, elongate muscle that is completely hidden by the deltoid and is often not clearly delineated from the infraspinatus  The subscapularis is a thick, triangular muscle that lies on the costal surface of the scapula and forms part of the posterior wall of the axilla.  SUPRASPINATUS  Proximal Attachment –  Supraspinous fossa of scapula  Distal Attachment  Superior facet of greater tubercle of humerus  Innervation  Suprascapular nerve (C4, C5, C6)  Action  Initiates and assists deltoid in abduction of arm and acts with rotator cuff muscles  INFRASPINATUS  Proximal Attachment –  Infraspinous fossa of scapula  Distal Attachment  Middle facet of greater tubercle of humerus  Innervation  Suprascapular nerve (C5, C6)  Action  Laterally rotate arm; help hold humeral head in glenoid cavity of scapula  TERES MINOR  Proximal Attachment –  Middle part of lateral border of scapula  Distal Attachment  Inferior facet of greater tubercle of humerus  Innervation  Axillary nerve (C5, C6)  Action  Laterally rotate arm; help hold humeral head in glenoid cavity of scapula  SUBSCAPULARIS  Proximal Attachment –  Subscapular fossa (most of anterior surface of scapula)  Distal Attachment  Lesser tubercle of humerus  Innervation  Upper and lower subscapular nerves (C5, C6, C7)  Action  Medially rotates and adduct arm; helps hold humeral head in glenoid cavity  SUBSCAPULAR SPACES (INTERMUSCULAR SPACES IN THE SCAPULAR REGION) Dr. D.O. Adeyemi Anatomy & Cell Biology Introduction  These are quadrangular (one) and triangular (two) inter-muscular spaces in the scapular region which are clearly seen from behind after reflecting the posterior part of the deltoid.  The knowledge of these spaces is essential during surgery in the shoulder region. QUADRANGULAR SPACE  BOUNDARIES  Superior: – Teres minor posteriorly – Subscapularis anteriorly – Capsule of shoulder joint between the above two muscles  Inferior: Teres major  Medial: Long head of the triceps  Lateral: Surgical neck of the humerus QUADRANGULAR SPACE  Structures passing through this space – Axillary nerve –  Posterior circumflex humeral artery and vein UPPER TRIANGULAR SPACE  BOUNDARIES  Superior: Teres minor  Lateral: Long head of triceps  Inferior: Teres major  Structures passing through this space  Circumflex scapular artery LOWER TRIANGULAR SPACE  BOUNDARIES  Medial: Long head of triceps  Lateral: Shaft of humerus  Superior: Teres major  Structures passing through this space  – Radial nerve  – Profunda brachii artery and vein GLENOHUMERAL JOINT  INTRODUCTION  The glenohumeral (shoulder) joint is a ball-and- socket type of synovial joint that permits a wide range of movement;  its mobility makes the joint relatively unstable.  ARTICULATION  The large, round humeral head articulates with the relatively shallow glenoid cavity of the scapula.  The shallow cavity is deepened slightly but effectively by the ring-like, fibrocartilaginous glenoid labrum  Both articular surfaces are covered with hyaline cartilage  ARTICULATION  The glenoid cavity accepts about a third of the humeral head.  Humeral head is held in the cavity by the tonus of the musculotendinous rotator cuff muscles  JOINT CAPSULE  The loose fibrous layer of the joint capsule surrounds the glenohumeral joint  It is attached medially to the margin of the glenoid cavity and laterally to the anatomical neck of the humerus  Superiorly, this part of the joint capsule ascends to the root of the coracoid process  JOINT CAPSULE  The joint capsule has two apertures:  an opening between the tubercles of the humerus for passage of the tendon of the long head of the biceps brachii  an opening situated anteriorly, inferior to the coracoid process that allows communication between the subscapular bursa and the synovial cavity of the joint. JOINT CAPSULE  JOINT CAPSULE  the inferior part of the capsule is the weakest part  It is the only part not reinforced by the rotator cuff muscles  It appear and lies in folds when the arm is adducted; however, it becomes taut when the arm is abducted.  JOINT CAPSULE  The synovial membrane lines the internal surface of the fibrous layer of the joint capsule and  reflects from it onto the glenoid labrum and the humerus, as far as the articular margin of the head.  JOINT CAPSULE  The synovial membrane also forms a tubular sheath for the tendon of the long head of the biceps brachii.  LIGAMENTS  Intrinsic ligaments:  The glenohumeral ligaments strengthen the anterior aspect of the joint capsule  The coracohumeral ligament strengthens the capsule superiorly,  Extrinsic ligaments:  The transverse humeral ligament runs obliquely from the greater to the lesser tubercle of the humerus, bridging over the intertubercular groove  The coracoacromial ligament spans the coracoacromial arch formed by the smooth inferior aspect of the acromion and the coracoid process  MOVEMENTS  The glenohumeral joint has more freedom of movement than any other joint in the body.  due to the laxity of its joint capsule and  the large size of the humeral head compared with the small size of the glenoid cavity  glenohumeral joint allows movements around three axes  Flexion - extension,  Abduction - adduction,  Medial and lateral rotation  Circumduction MUSCLES MOVING THE GLENOHUMERAL JOINT  Flexors  Clavicular head of pectoralis major  Anterior part of deltoid  Coracobrachialis and biceps brachii acts synergistically with the first two  sternocostal head of pectoralis major acts from a fully extended position to its own coronal plane  Extensors  Posterior part of deltoid  Teres major acts synergistically  Latissimus dorsi, sternocostal head of pectoralis major, and long head of triceps act from fully flexed position to their own (coronal) planes MUSCLES MOVING THE GLENOHUMERAL JOINT  Abductors  Deltoid (as a whole, but especially central fibres)  Supraspinatus acting synergistically (initiates the movement)  Adductors  Pectoralis major;  latissimus dorsi  Subscapularis;  infraspinatus;  teres minor MUSCLES MOVING THE GLENOHUMERAL JOINT  Medial rotators  Subscapularis  Pectoralis major, anterior fibers of deltoid, latissimus dorsi act synergistically  Lateral rotators  Infraspinatus  Teres minor; posterior fibers of deltoid act synergistically  BLOOD SUPPLY  anterior and posterior circumflex humeral arteries and  branches of the suprascapular artery  INNERVATION  suprascapular, axillary, and lateral pectoral nerves BURSAE AROUND THE GLENOHUMERAL JOINT  The subscapular bursa  located between the tendon of the subscapularis and the neck of the scapula  It protects the tendon where it passes inferior to the root of the coracoid process and over the neck of the scapula  BURSAE AROUND THE GLENOHUMERAL JOINT  Subacromial Bursa (subdeltoid bursa)  located between the acromion, coracoacromial ligament and deltoid superiorly and the supraspinatus tendon and joint capsule of the glenohumeral joint inferiorly  it facilitates movement of the supraspinatus tendon under the coracoacromial arch and of the deltoid over the joint capsule of the glenohumeral joint and the greater tubercle of the humerus ANATOMY OF THE BREAST Dr. D.O. Adeyemi  INTRODUCTION  The breasts are paired structures located on the anterior thoracic wall, in the pectoral region.  They are present in both males and females, yet are more prominent in females following puberty.  In females, the breasts contain the mammary glands – an accessory gland of the female reproductive system.  The mammary glands are the key structures involved in lactation.  LOCATION & POSITION  The breast is located on the anterior thoracic wall.  It extends horizontally from the lateral border of the sternum to the mid-axillary line.  Vertically, it spans between the 2nd and 6th costal cartilages.  It lies superficially to the pectoralis major and serratus anterior muscles.  PARTS  The breast can be considered to be composed of two regions:  Circular body – largest and most prominent part of the breast.  Axillary tail – smaller part, runs along the inferior lateral edge of the pectoralis major towards the axillary fossa.  PARTS  At the centre of the breast is the nipple, composed mostly of smooth muscle fibres.  Surrounding the nipple is a pigmented area of skin termed the areolae.  PARTS  There are numerous sebaceous glands within the areolae – these enlarge during pregnancy, secreting an oily substance that acts as a protective lubricant for the nipple. BREAST STRUCTURE  The breast is composed of mammary glands surrounded by a connective tissue stroma.  The mammary glands are modified sweat glands. They consist of a series of ducts and secretory lobules (15-20). BREAST STRUCTURE  Each lobule consists of many alveoli drained by a single lactiferous duct. These ducts converge at the nipple like spokes of a wheel.  The connective tissue stroma is a supporting structure which surrounds the mammary glands. It has a fibrous and a fatty component. BREAST STRUCTURE  The fibrous stroma condenses to form suspensory ligaments (of Cooper).  These ligaments have two main functions:  Attach and secure the breast to the dermis and underlying pectoral fascia.  Separate the secretory lobules of the breast. BREAST STRUCTURE  The base of the breast lies on the pectoral fascia – a flat sheet of connective tissue associated with the pectoralis major muscle. It acts as an attachment point for the suspensory ligaments.  There is a layer of loose connective tissue between the breast and pectoral fascia – known as the retromammary space. This is a potential space, often used in reconstructive plastic surgery.  VASCULATURE  Arterial supply to the medial aspect of the breast is via the internal thoracic artery (also known as internal mammary artery) – a branch of the subclavian artery.  The lateral part of the breast receives blood from four vessels:  Lateral thoracic and thoracoacromial branches – originate from the axillary artery.  Lateral mammary branches – originate from the posterior intercostal arteries (derived from the aorta). They supply the lateral aspect of the breast in the 2nd 3rd and 4th intercostal spaces.  Mammary branch – originates from the anterior intercostal artery.  VENOUS DRAINAGE  The veins of the breast correspond with the arteries, draining into the axillary and internal thoracic veins.  LYMPHATICS  The lymphatic drainage of the breast is of great clinical importance due to its role in the metastasis of breast cancer cells.  There are three groups of lymph nodes that receive lymph from breast tissue – the axillary nodes (75%), parasternal nodes (20%) and posterior intercostal nodes (5%).  The skin of the breast also receives lymphatic drainage: Skin – drains to the axillary, inferior deep cervical and infraclavicular nodes. Nipple and areola – drains to the subareolar lymphatic plexus.  INNERVATION  The breast is innervated by the anterior and lateral cutaneous branches of the 4th to 6th intercostal nerves. These nerves contain both sensory and autonomic nerve fibres (the autonomic fibres regulate smooth muscle and blood vessel tone).  It should be noted that these nerves do not control the production and secretion of milk. This is regulated by the hormones prolactin and oxytocin, which are secreted from the pituitary gland. Clinical Relevance: Breast Cancer  Breast cancer is one of the most common type of cancer. It is more common in women than men.  Common presentations associated with breast cancer are due to blockages of the lymphatic drainage.  Metastasis commonly occurs through the lymph nodes. It is most likely to be the axillary lymph nodes that are involved.  Following this, the cancer can spread to distant places such as the liver, lungs, bones and ovary.  ANTERIOR AND POSTERIOR COMPARTMENTS OF THE ARM Dr. D.O. Adeyemi  INTRODUCTION  The arm extends from the shoulder to the elbow.  Two types of movement occur between the arm and the forearm at the elbow joint:  Flexion - extension and  Pronation - supination.  The muscles performing these movements are clearly divided into anterior and posterior groups.  MUSCLES OF THE ARM  There are four major arm muscles,  three flexors in the anterior (flexor) compartment, innervated by the musculocutaneous nerve  biceps brachii,  brachialis, and  coracobrachialis  one extensor is in the posterior compartment, innervated by the radial nerve  triceps brachii  MUSCLES OF THE ARM  A distally placed assistant to the triceps, the anconeus, also lies within the posterior compartment  BICEPS BRACHII  biceps brachii is a fusiform muscle which usually have two headed proximal attachment  The usual two heads of the biceps arise proximally by tendinous attachments to processes of the scapula, their fleshy bellies uniting just distal to the middle of the arm  From the conjoint belly, a single biceps tendon forms distally and attaches primarily to the radius  BICEPS BRACHII  Proximal Attachment –  Short head: tip of coracoid process of scapula  Long head: supraglenoid tubercle of scapula  Distal Attachment  Tuberosity of radius and fascia of forearm via bicipital aponeurosis  Innervation  Musculocutaneous nerve(C5, C6)  Action  Supinates forearm and, when it is supine, flexes forearm;  short head resists dislocation of shoulder BICEPS BRACHII  BRACHIALIS  The brachialis is a flattened fusiform muscle that lies posterior (deep) to the biceps.  Its distal attachment covers the anterior part of the elbow joint  The brachialis is the main flexor of the forearm  BRACHIALIS  Proximal Attachment –  Distal half of anterior surface of humerus  Distal Attachment  Coronoid process and tuberosity of ulna  Innervation  Musculocutaneous nerve(C5, C6)  Action  Flexes forearm in all positions  CORACOBRACHIALIS  The coracobrachialis is an elongated muscle in the superomedial part of the arm.  It is a useful landmark for locating other structures in the arm  CORACOBRACHIALIS  Proximal Attachment –  Tip of coracoid process of scapula  Distal Attachment  Middle third of medial surface of humerus  Innervation  Musculocutaneous nerve(C5, C6, C7)  Action  flex and adduct arm;  resists dislocation of shoulder  TRICEPS BRACHII  The triceps brachii is a large fusiform muscle in the posterior compartment of the arm  the triceps has three heads: long, lateral, and medial.  The triceps is the main extensor of the forearm.  TRICEPS BRACHII  Proximal Attachment –  Long head: infra-glenoid tubercle of scapula  Lateral head: posterior surface of humerus, superior to radial groove  Medial head: posterior surface of humerus, inferior to radial groove  Distal Attachment  Proximal end of olecranon of ulna and fascia of forearm  Innervation  Radial nerve (C6, C7, C8)  Action  Chief extensor of forearm; long head resists dislocation of humerus; especially important during abduction  ANCONEUS  The anconeus is a small, relatively unimportant triangular muscle on the posterolateral aspect of the elbow;  it is usually partially blended with the triceps  The anconeus helps the triceps extend the forearm and tenses of the capsule of the elbow joint,  ANCONEUS  Proximal Attachment –  Lateral epicondyle of humerus  Distal Attachment  Lateral surface of olecranon and  superior part of posterior surface of ulna  Innervation  Radial nerve (C7, C8, T1)  Action  Assists triceps in extending forearm;  stabilizes elbow joint;  may abduct ulna during pronation  HUMAN ANATOMY I (CLI 213) (4 Unit) ‘WALE ADEYEMI ANATOMY AND CELL BIOLOGY FACULTY OF BASIC MEDICAL SCIENCES  TOPIC: BRACHIAL PLEXUS  RATIONALE The brachial plexus is the source of innervation of all musculoskeletal structures of the upper limb. Injury to any of the parts of the brachial plexus would lead to paralysis of the muscles being innervated by that part of the brachial plexus  LEARNING OBJECTIVES ▪ By the end of the lesson, the students should be able to: ✓Define brachial plexus ✓Explain the formation of brachial plexus ✓Enumerate the branches of the brachial plexus, their courses and function ✓List common causes and manifestation of brachial plexus injury ✓Apply the knowledge of brachial plexus to clinical practice  INTRODUCTION TO CONTENT ▪ Definition ▪ Formation [ Root, Trunk, Division, Cord] ▪ Branches ✓Supraclavicular ✓Infraclavicular (medial, lateral and posterior cord branches) ▪ Applied Anatomy  Definition Brachial plexus is a major nerve network which supply the upper limbs and some part of the thoracic wall. It begins in the neck and extends into the axillla. Almost all the branches of the brachial plexus arise in the axilla.  FORMATION Brachial plexus is formed by the union of ventral rami of the lower four cervical spinal nerve and the ventral ramus of first thoracic spinal nerve. (i.e. C5 – C8 and T1). The normal formation of brachial plexus can be divided into 4 parts: Root Trunk Division Cords FORMATION FORMATION  FORMATION Root:- ventral ramii of C5 – C8 and T1 Trunk:– there are three trunks (upper, middle and lower) formed from 5 roots. Upper trunk:– is formed by the union of C5 and C6 Middle trunk: – is a continuation of C7 Lower trunk:– is formed by the union of C8 and T1 FORMATION  FORMATION Division: – Each trunk of the brachial plexus divides into two Anterior division Posterior division The division unites to form the cord. Generally anterior division ultimately gives rise to nerve supplying upper limb flexor compartment while the posterior division give rise to nerves supplying the upper limbs extensor compartment FORMATION  FORMATION Cords: - There are 3 cords formed from the division and are named based on their relative position with the 2nd part of the axiliary artery. Lateral Cord:- is formed by the union of the anterior division of the upper and middle trunk. Medial cord:- is the continuation of the anterior division of the lower trunk. Posterior cord:- is formed by the union of the posterior division of the three of the 3 trunks. BRANCHES OF THE BRACHIAL PLEXUS supraclavicular branches infraclavicular branches. Supraclavicular branches arise superior to the clavicle from the roots and trunk of the brachial plexus. The infraclavicular branches arise inferior to the clavicle from the cord of the brachial plexus. SUPRACLAVICULAR BRANCHES BRANCHES FROM THE ROOTS Branch to phrenic nerve (C5) - supplies the central part of the diaphragm. Dorsal scapular nerve (C5) - supply the rhomboid (major and minor) muscles Long thoracic nerve (C5 C6 and C7) - supplying serratus anterior muscle. BRANCHES FROM THE TRUNK (superior trunk) Suprascapular nerve (C5, C6) – supply the supraspinatus and infraspinatus. Nerve to subclavius (C5 –C6) FORMATION  INFRACLAVICULAR BRANCHES LATERAL CORD BRANCHES Lateral pectoral nerve (C5, C6, C7) – Primarily innervates the pectoralis major Musculocutaneus nerve (C7, C6, C7) – supplies coracobrachialis, biceps brachi and brachialis muscle. becomes the lateral cutanous nerve of the forearm. It also supply the elbow joint. Lateral root of median nerve (C5, C6 and C7) – it joints the medial root of the median nerve from the medial cord and continue as the median nerve.  INFRACLAVICULAR BRANCHES Medial Cord Branches Medial pectoral nerve (C8, T1) – supplies pectoralis minor and the sternocostal part of p. major Medial cutanous nerve of the arm (C8, T1) – the smallest and most medial of all branches. supplies the skin over the anterior and medial part of the arm Medial cutanous nerve of the fore arm. (C8, T1) – it supplies the skin of the medial side of the forearm.  INFRACLAVICULAR BRANCHES Medial Cord Branches (contd) Ulnar nerve:- (C7, C8, T1) – It supplies the flexor carpi ulnaris and medial half of flexor digitorum profundus. It continues distally to the hand and supplies Palmaris brevis, medial 1½ of palmar skin and the skin overlying medial 1½ of both surfaces of the finger.  INFRACLAVICULAR BRANCHES Medial Cord Branches (contd) Medial root of median nerve (C8, T1) It supplies all the muscles on the flexor compartment of the forearm except those supplied by ulnar nerve. It descends to the hand and supply the thenar muscle of the hand and becomes cutanous to supply the lateral 3 ½ of the palmar skin and and skin overlying the lateral 3 ½ of the anterior surface of the digits.  INFRACLAVICULAR BRANCHES Posterior Cord Branches Upper subscapular nerve (C6) – supplies upper part of the subscapularis Lower subscapularis nerve (C5, C6) – supplies the lower part of subscapularis and teres major. Thoracodorsal nerve (C6, C7, C8) – runs along the posterior axillary wall, crosses the inferior border of teres major and enters the latissimus dorsi to supply it.  INFRACLAVICULAR BRANCHES Axillary (circumflex humeral) Nerve (C5, C6) – it courses round to the surgical neck of the humerus and supplies the posterior fibres of deltoid muscle, teres minor. It also sends cutanous branch to supply the skin overlying deltoid. It sends branch to the shoulder joint and becomes the posterior cutanous nerve of the arm which supply the skin on the posterior surface of the arm.  INFRACLAVICULAR BRANCHES Radial Nerve (C5, 6, 7, 8 & T1) – It is the largest branch of the brachial plexus. It supply all the muscles of the extensor or compartment of the arm and forearm. It supplies the skin of the posterior surface of the arm and forearm and also send branch that supply the skin overlying the lateral 3½ of the dorsum of the hand and skin overlying the lateral 3 ½ of the posterior surface of the digit.  Applied Anatomy Erb-Duchenne palsy Injuries to superior part of the brachial plexus (C5 and C6) – result from an excessive increase in the angle between the neck and the shoulder. causes Obstetrics practices A fall on the shoulder  Applied Anatomy muscles of the shoulder and arm supplied by the C5 and C6 (deltoid, biceps, brachialis, and brachioradialis) are paralysed. The usual clinical appearance is an upper limb with an adducted shoulder, medially rotated arm, and extended elbow.  Applied Anatomy Klumpke paralysis Injuries to inferior parts of the brachial plexus Causes The short muscles of the hand are affected, and a claw hand results