Human Anatomy 1 PDF

HUMAN ANATOMY 1 BY OLUSEYI FABIYI  COURSE CONTENT Osteology Axilla and its contents Breast Shoulder region Upper arm, cubital fossa, forearm and Hand Joints of Upper limb Thoracic walls; Mediastinum; pericardium and Heart; Pleura and Lung...

HUMAN ANATOMY 1 BY OLUSEYI FABIYI  COURSE CONTENT Osteology Axilla and its contents Breast Shoulder region Upper arm, cubital fossa, forearm and Hand Joints of Upper limb Thoracic walls; Mediastinum; pericardium and Heart; Pleura and Lung Abdominal wall and External hernias External genital organs; Peritoneum Gastrointestinal tract and associated glands Diaphragm; Pelvis and Perineum Axial skeleton… The skeleton can be divided into two main parts. The axial skeleton consists of 80 bones. The primary bones of the axial skeleton are the skull, spine, ribs and sternum (thorax). Anterior means front; posterior means back. This is an anterior view of the skeleton. Appendicular skeleton… The appendicular skeleton consists of 126 bones. The primary bones of this skeleton are the shoulder or pectoral girdle, arms, hands, pelvic girdle, legs, and feet. Functions of Bones are composed of about 50% water and 50% a bones… solid, calcified, rigid substance known as osseous (AH see us) tissue. 1. Bones provide shape, support, and the framework of the body. 2. Bones protect internal organs. 3. Bones serve as a storage place for minerals such as salts, calcium, and phosphorus. Functions of bones… 4. Bones play an important role in hematopoiesis (hee MAT ah poh EE siss)… the formation of blood cells that takes place in bone marrow. 5. Bones provide a place to attach muscles. 6. Bones make movement possible through articulation (manner in which the parts come together at a joint). Classifications of bones by shape… Bones can be classified by shape. 4 of those classifications are: LONG bones include the femur (thigh), tibia (larger shin), fibula (smaller shin bone), humerus (upper arm), radius (larger forearm), and ulna (smaller forearm). Classifications of bones by shape… Bones can be classified by shape. 4 of those classifications are: SHORT bones include the carpals of the wrist and tarsals of the ankle. Classifications of bones by shape… Bones can be classified by shape. 4 of those classifications are: FLAT bones include the skull, sternum (breastbone), and scapula (shoulder bone). Classifications of bones by shape… Bones can be classified by shape. 4 of those classifications are: IRREGULAR bones include the vertebrae (spine), and pelvic. Bone growth and resorption… Bone is continually remodeled. It is broken down by osteoclasts in a process called resorption, and formed again by osteoblasts. Bone formation and healing slow down as part of the aging process. Osteoporosis is an age-related loss of bone mass or density.  Bone The features in this long bone illustrate those found in all bones. structure… Epiphysis (ĭ PIF ah siss) - growing end Diaphysis (dye AF ah siss) - shaft Periosteum (peri OSS tee um) - outside covering Medullary (MED ul air ee)- inner space containing bone marrow Endosteum (en DOS tee um)- lining of medullary cavity Joints… A joint is a place where two or more bones connect. The manner in which they connect determines the type of movement allowed at that joint. A synarthrosis (sĭn ahrTHROW siss) is a joint that allows no movement. An example would be a cranial suture. A amphiarthrosis (am fee ahr THROW siss) is Joints… a joint that allows slight movement. An example would be a vertebra. A diarthrosis (dye ahr THROW siss) is a joint that allows free movement in a variety of directions, such as knee, hip, elbow, wrist, and foot. Types of body movements at diarthrotic joints… Flexion: Abduction: moving a body bending a limb part away from the middle. Extension: Adduction: moving a body straightening a part toward the middle. flexed limb Types of body movements at diarthrotic joints… Supination: lying supine or face upward; or turning the Circumduction: palm or foot upward. moving a body Pronation: lying prone or face part in a circular downward; or turning the motion palm downward. Types of body movements at diarthrotic joints… Dorsiflexion: Protraction: moving a body bending a body forward. part backwards. Retraction: moving a body part backward. Types of body movements at diarthrotic joints… Rotation: Inversion: turning inward. moving a body Eversion: turning outward. part around a central axis  SHOULDER REGION: SCAPULA The scapula is 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. It is a triangular, flat bone, which serves as a site for attachment for many (17) muscles. Its has three borders, three angles and three surfaces (Superior, lateral and medial borders. Superior, inferior and lateral angles. Coastal or anterior, posterior and lateral Coastal or Anterior Surface The costal (anterior) surface of the scapula faces the ribcage It contains a large concave depression over most of its surface, known as the subscapular fossa. The subscapularis (rotator cuff muscle) originates from this fossa. Originating from the superolateral surface of the costal scapula is the coracoid process Three muscles attach to the coracoid process: the pectoralis minor, coracobrachialis, and the short head of the biceps brachii. LATERAL SURFACE The lateral surface of the scapula faces the humerus. It is the site of the glenohumeral joint, and of various muscle attachments. Its important bony landmarks include: Glenoid fossa – a shallow cavity, located superiorly on the lateral border. – It articulates with the head of the humerus to form the glenohumeral (shoulder) joint. Supraglenoid tubercle – a roughening immediately superior to the glenoid fossa. – The place of attachment of the long head of the biceps brachii. Infraglenoid tubercle – a roughening immediately inferior to the glenoid fossa. – POSTERIOR SURFACE The posterior surface of the scapula faces outwards. It is a site of origin for the majority of the rotator cuff muscles of the shoulder. It is marked by: Spine Acromion Infraspinous fossa Supraspinous fossa- The supraspinatus muscle originates from this area. Articulations The scapula has two main articulations: Glenohumeral joint – between the glenoid fossa of the scapula and the head of the humerus. Acromioclavicular joint – between the acromion of the scapula and the clavicle. Muscle Direction Region Pectoralis Minor insertion coracoid process Coracobrachialis origin coracoid process Serratus Anterior insertion medial border Triceps Brachii (long head) origin infraglenoid tubercle Biceps Brachii (short head) origin coracoid process Biceps Brachii (long head) origin supraglenoid tubercle Subscapularis origin subscapular fossa Rhomboid Major insertion medial border Rhomboid Minor insertion medial border Levator Scapulae insertion medial border Trapezius insertion spine of scapula Deltoid origin spine of scapula Supraspinatus origin supraspinous fossa Infraspinatus origin infraspinous fossa Teres Minor origin lateral border Teres Major origin lateral border Latissimus Dorsi (a few fibers, origin inferior angle attachment may be absent) Omohyoid origin superior border  CLAVICLE The clavicle (collarbone) extends between the manubrium of the sternum and the acromion of the scapula It is classed as a long bone and can be palpated along its length. In thin individuals, it is visible under the skin. The clavicle has three main functions: Attaches the upper limb to the trunk as part of the ‘shoulder girdle’. Protects the underlying neurovascular structures supplying the upper limb. Transmits force from the upper limb to the axial skeleton. The clavicle is a slender bone with an ‘S’ shape. Facing forward, the medial aspect is convex, and the lateral aspect concave. It can be divided into a sternal end, a shaft and an acromial end. Sternal (medial) End The sternal end contains a large facet – for articulation with the manubrium of the sternum at the sternoclavicular joint. The inferior surface of the sternal end is marked by a rough oval depression for the costoclavicular ligament (a ligament of the SC joint). Shaft The shaft of the clavicle acts a point of origin and attachment for several muscles – deltoid, trapezius, subclavius, pectoralis major, sternocleidomastoid and sternohyoid.  Acromial (lateral) End The acromial end houses a small facet for articulation with the acromion of the scapula at the acromioclavicular joint. It also serves as an attachment point for two ligaments: Conoid tubercle – attachment point of the conoid ligament, the medial part of the coracoclavicular ligament. Trapezoid line – attachment point of the trapezoid ligament, the lateral part of the coracoclavicular ligament. The coracoclavicular ligament is a very strong structure, effectively suspending the weight of the upper limb from the clavicle.  HUMERUS The humerus is a long bone of the upper limb, which extends from the shoulder to the elbow. 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. Proximal Landmarks The proximal humerus is marked by a head, anatomical neck, surgical neck, greater and lesser tuberosity and intertubercular sulcus. The greater tuberosity It serves as an attachment site for three of the rotator cuff muscles– supraspinatus, infraspinatus and teres minor.  The lesser tuberosity is much smaller, and more medially located on the bone. It only has an anterior surface. It provides attachment for the last rotator cuff muscle – the subscapularis. Separating the two tuberosities is a deep groove, known as the intertubercular sulcus. The tendon of the long head of the biceps brachii emerges from the shoulder joint and runs through this groove. The edges of the intertubercular sulcus are known as lips. Pectoralis major, teres major and latissimus dorsi insert on the lips of the intertubercular sulcus. CLINICAL RELEVANCE: Surgical Neck Fracture- The key neurovascular structures at risk here are the axillary( leading to paralysis of Deltoid and Tere minor muscles-abduction problem) nerve and posterior circumflex SHAFT The shaft of the humerus is the site of attachment for various muscles. Cross section views reveal it to be circular proximally and flattened distally. On the lateral side of the humeral shaft is a roughened surface where the deltoid muscle attaches. This is known is as the deltoid tuberosity. The radial (or spiral) groove: The radial nerve and profunda brachii artery lie in this groove. The following muscles attach to the humerus along its shaft: Anteriorly – coracobrachialis, deltoid, brachialis, brachioradialis. Posteriorly – medial and lateral heads of the triceps Distal Region The lateral and medial borders of the distal humerus form medial and lateral supraepicondylar ridges. The lateral supraepicondylar ridge is more roughened, providing the site of common origin of the forearm extensor muscles. Immediately distal to the supraepicondylar ridges are extracapsular projections of bone, the lateral and medial epicondyles. Also located on the distal portion of the humerus are three depressions, known as the coronoid, radial and olecranon fossae. They accommodate the forearm bones during flexion or extension at the elbow. Articulations The proximal region of the humerus articulates with the glenoid fossa of the scapula to form the glenohumeral joint (shoulder joint). Distally, at the elbow joint, the capitulum of the humerus articulates with the head of the radius and the trochlea of the humerus articulates with the trochlear notch of the ulna. CLINICAL RELEVANCE: Supracondylar fracture: This can damage Brachial artery as well as anterior interosseous nerve. Mid-Shaft fracture: This may cause fracture of the humerus risk damage to the radial nerve and profunda brachii artery.  ULNA The ulna is a long bone in the forearm. It lies medially and parallel to the radius, the second of the forearm bones. The ulna acts as the stabilising bone, with the radius pivoting to produce movement. Proximally, the ulna articulates with the humerus at the elbow joint. Distally, the ulna articulates with the radius, forming the distal radio-ulnar joint. The proximal end of the ulna articulates with the trochlea of the humerus. To enable movement at the elbow joint, the ulna has a specialised structure, with bony prominences for muscle attachment. Shaft of the Ulna The ulnar shaft is triangular in shape, with three borders and three surfaces. As it moves distally, it decreases in width. The three surfaces: Anterior – site of attachment for the pronator quadratus muscle distally. Posterior – site of attachment for many muscles. Medial – unremarkable. The three borders: Posterior – palpable along the entire length of the forearm posteriorly Interosseous – site of attachment for the interosseous membrane, which spans the distance between the two forearm bones. Anterior – unremarkable.  RADIUS The radius is a long bone in the forearm. It lies laterally and parallel to ulna, the second of the forearm bones. The radius articulates in four places: Elbow joint – Partly formed by an articulation between the head of the radius, and the capitulum of the humerus. Proximal radioulnar joint – An articulation between the radial head, and the radial notch of the ulna. Wrist joint – An articulation between the distal end of the radius and the carpal bones. Distal radioulnar joint – An articulation between the ulnar notch and the head of the ulna.  Forearm Muscles in the Anterior Compartment of the The muscles in the anterior Forearmof the forearm are compartment organised into three layers: 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. This muscle group is associated with pronation of the forearm, flexion of the wrist and flexion of the fingers. They are mostly innervated by the median nerve (except for the flexor carpi ulnaris and medial half of flexor digitorum profundus, which are innervated by the ulnar nerve), and they receive arterial supply from the ulnar artery and radial artery  Muscles in the Posterior Compartment of the Forearm The muscles in the posterior compartment of the forearm are commonly known as the extensor muscles. The general function of these muscles is to produce extension at the wrist and fingers. They are all innervated by the radial nerve. The muscles in this compartment are organised into two layers; deep and superficial. These two layers are separated by a layer of fascia. Superficial Muscles The superficial layer of the posterior forearm contains seven muscles. Four of these muscles (extensor carpi radialis brevis, extensor digitorum, extensor carpi ulnaris and extensor digiti minimi) share a common tendinous origin at the lateral epicondyle Brachioradialis The brachioradialis is a paradoxical muscle. Its origin and innervation are characteristic of an extensor muscle, but it is actually a flexor at the elbow. Extensor Carpi Radialis Longus and Brevis The extensor carpi radialis muscles are situated on the lateral aspect of the posterior forearm. Due to their position, they are able to produce abduction as well as extension at the wrist.  BONES OF THE HAND The bones of the hand provide support and flexibility to the soft tissues. They can be divided into three categories: Carpal bones (Proximal) – A set of eight irregularly shaped bones. These are located in the wrist area. Metacarpals – There are five metacarpals, each one related to a digit Phalanges (Distal) – The bones of the fingers. Each finger has three phalanges, except for the thumb, which has two. Carpal Bones The carpal bones are a group of eight, irregularly shaped bones. They are organised into two rows: proximal and distal. Proximal Row (lateral to medial) Distal Row (lateral to medial) Scaphoid Trapezium Lunate Trapezoid Triquetrum Capitate Pisiform (a sesamoid bone, formed within Hamate (has a projection on its palmar the tendon of the flexor carpi ulnaris) surface, known as the ‘hook of hamate’  Collectively, the carpal bones form an arch in the coronal plane. A membranous band, the flexor retinaculum, spans between the medial and lateral edges of the arch, forming the carpal tunnel. Proximally, the scaphoid and lunate articulate with the radius to form the wrist joint(also known as the ‘radio- carpal joint’). In the distal row, all of the carpal bones articulate with the metacarpals. Metacarpal Bones The metacarpal bones articulate proximally with the carpals, and distally with the proximal phalanges. They are numbered, and each associated with a digit: Metacarpal I – Thumb. Metacarpal II – Index finger. Metacarpal III – Middle finger. Metacarpal IV – Ring finger. Metacarpal V – 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. Clinical Relevance: Fractures of the Metacarpals There are two common fractures of the metacarpals: Boxer’s fracture – A fracture of the 5th metacarpal neck. It is usually caused by a clenched fist striking a hard object. The distal part of the fracture is displaced anteriorly, producing shortening of the affected finger. Bennett’s fracture – A fracture of the 1st metacarpal base, caused by forced hyperabduction of the thumb. This fracture extends into the first carpometacarpal joint leading to instability and subluxation of the joint. As a result, it often needs surgical repair. Phalanges The phalanges are the bones of the fingers. The thumb has a proximal and distal phalanx, while the rest of the digits have proximal, middle and distal phalanges  Muscles of the Hand Muscles acting on the hand can be divided into two groups: extrinsic and intrinsic muscles. The extrinsic muscles are located in the anterior and posterior compartments of the forearm. They control crude movements and produce a forceful grip. The intrinsic muscles of the hand are located within the hand itself. They are responsible for the fine motor functions of the hand. They are arranged in group of five muscular compartments.  Intrinsic muscles Thenar Muscles The thenar muscles are three short muscles located at the base of the thumb. The muscle bellies produce a bulge, known as the thenar eminence. They are responsible for the fine movements of the thumb. The median nerve innervates all the thenar muscles. Opponens Pollicis The opponens pollicis is the largest of the thenar muscles, and lies underneath the other two. Abductor Pollicis Brevis This muscle is found anteriorly to the opponens pollicis and proximal to the flexor pollicis brevis. Flexor Pollicis Brevis The most distal of the thenar muscles.  Intrinsic Muscles of the Hand Hypothenar Muscles The hypothenar muscles produce the hypothenar eminence – a muscular protrusion on the medial side of the palm, at the base of the little finger. These muscles are similar to the thenar muscles in both name and organisation. The ulnar nerve innervates the muscles of the hypothenar eminence. Opponens Digiti Minimi The opponens digit minimi lies deep to the other hypothenar muscles. Abductor Digiti Minimi The most superficial of the hypothenar muscles. Flexor Digiti Minimi Brevis This muscle lies laterally to the abductor digiti minimi. Lumbricals These are four lumbricals in the hand, each associated with a finger. They are very crucial to finger movement, linking the extensor tendons to the flexor tendons. Denervation of these muscles is the basis for the ulnar claw and hand of benediction. Attachments: Each lumbrical originates from a tendon of the flexor digitorum profundus. They pass dorsally and laterally around each finger, and inserts into the extensor hood. Actions: Flexion at the MCP joint and extension at the interphalangeal (IP) joints of each digit. Innervation: 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. Interossei The interossei muscles are located between the metacarpals. They can be divided into two groups: the dorsal and palmar interossei. In addition to their actions of abduction (dorsal interossei) and adduction (palmar interossei) of the fingers, the interossei also assist the lumbricals in flexion at the MCP joints and extension at the IP joints. Dorsal Interossei The most superficial of all dorsal muscles, these can be palpated on the dorsum of the hand. There are four dorsal interossei muscles. Palmar Interossei These are located anteriorly on the hand. There are three palmar interossei muscles – although some texts report a fourth muscle at the base of the proximal phalanx of the thumb. Other Muscles in the Palm There are two other muscles in the palm that are not lumbricals or interossei and do not fit in the hypothenar or thenar compartments: Palmaris Brevis This is a small, thin muscle, found very superficially in the subcutaneous tissue of the hypothenar eminence. Innervation: Ulnar nerve Adductor Pollicis This is large triangular muscle with two heads. The radial artery passes anteriorly through the space between the two heads, forming the deep palmar arch. Innervation: Ulnar nerve. The Extensor Tendon Compartments of the Wrist The extensor tendon compartments of the wrist are six tunnels which transmit the long extensor tendons from the forearm into the hand They are located on the posterior aspect of the wrist. Each tunnel is lined internally by a synovial sheath and separated from one another by fibrous septa. Compartment 1 The first extensor compartment is located on the lateral (radial) aspect of the wrist. It transmits two tendons: Extensor pollicis brevis Abductor pollicis longus These tendons form the lateral border of the anatomical snuffbox. Compartment 2 The second extensor compartment contains the tendons of the extensor carpi radialislongus and extensor carpi radialis brevis. This compartment is separated from compartment 3 by Lister’s tubercle – a bony prominence of the distal aspect of the radius. Compartment 3 Compartment three conducts the extensor pollicis longus tendon – this forms the medial border of the anatomical snuffbox. Compartment 4 The 4th extensor compartment of the wrist transmits the tendons of the extensor digitorum and extensor indicis. Compartment 5 Compartment five contains the extensor digiti minimi tendon, which travels into the little finger. Compartment 6 The sixth compartment is the located on the medial (ulnar) aspect of the wrist. It conducts the tendon of the extensor carpi ulnaris.  The Brachial Plexus The brachial plexus is a network of nerve fibres that supplies the skin and musculature of the upper limb. It begins in the root of the neck, passes through the axilla, and runs through the entire upper extremity. The plexus is formed by the anterior rami (divisions) of cervical spinal nerves C5, C6, C7 and C8, and the first thoracic spinal nerve, T1. The brachial plexus is divided into five parts; roots, trunks, divisions, cords and branches (a good mnemonic for this is Read That Damn Cadaver Book). There are no functional differences between these divisions – they are simply used to aid explanation of the brachial plexus.  Roots The ‘roots’ refer the anterior rami of the spinal nerves that comprise the brachial plexus. These are the anterior rami of spinal nerves C5, C6, C7, C8, and T1. At each vertebral level, paired spinal nerves arise. They leave the spinal cord via the intervertebral foramina of the vertebral column. Each spinal nerve then divides into an anterior and a posterior ramus. The roots of the brachial plexus are formed by the anterior rami of spinal nerves C5-T1 (the posterior divisions innervate the skin and musculature of the intrinsic back muscles). After their formation, these nerves pass between the anterior and medial scalene muscles to Trunks At the base of the neck, the roots of the brachial plexus converge to form three trunks. These structures are named by their relative anatomical location: Superior trunk – a combination of C5 and C6 roots. Middle trunk – continuation of C7. Inferior trunk – combination of C8 and T1 roots. The trunks traverse laterally, crossing the posterior triangle of the neck. Divisions Each trunk divides into two branches within the posterior triangle of the neck. One division moves anteriorly (toward the front of the body) and the other posteriorly (towards the back of the body). Thus, they are known as the anterior and posterior divisions. We now have three anterior and three posterior nerve fibres. These divisions leave the posterior triangle and pass into the axilla. Cords Once the anterior and posterior divisions have entered the axilla, they combine together to form three cords, named by their position relative to the axillary artery. The lateral cord is formed by: 1. The anterior division of the superior trunk 2. The anterior division of the middle trunk The posterior cord is formed by: 1. The posterior division of the superior trunk 2. The posterior division of the middle trunk 3. The posterior division of the inferior trunk The medial cord is formed by: 1. The anterior division of the inferior trunk. 2. The cords give rise to the major branches of the brachial plexus. Major Branches In the axilla and the proximal aspect of the upper limb, the three cords give rise to five major branches. These nerves continue into the upper limb to provide innervation to the muscles and skin present. In this section, we shall concentrate on these five nerves. Musculocutaneous Nerve Roots: C5, C6, C7. Motor Functions: Innervates the brachialis, biceps brachii and coracobrachialis muscles. Sensory Functions: Gives off the lateral cutaneous branch of the forearm, which innervates the lateral half of the anterior forearm, and a small lateral portion of the posterior forearm. Axillary Nerve Roots: C5 and C6. Motor Functions: Innervates the teres minor and deltoid muscles. Sensory Functions: Gives off the superior lateral cutaneous nerve of arm, which innervates the inferior region of the deltoid Median Nerve Roots: C6 – T1. (Also contains fibres from C5 in some individuals). Motor Functions: Innervates most of the flexor muscles in the forearm, the thenar muscles, and the two lateral lumbricals associated with the index and middle fingers. Sensory Functions: Gives off the palmar cutaneous branch, which innervates the lateral part of the palm, and the digital cutaneous branch, which innervates the lateral three and a half fingers on the anterior (palmar) surface of the hand. Radial Nerve Roots: C5 – T1. Motor Functions: Innervates the triceps brachii, and the muscles in the posterior compartment of the forearm (which are primarily, but not exclusively, extensors of the wrist and fingers). Sensory Functions: Innervates the posterior aspect of the arm and forearm, and the posterolateral aspect of the hand. Ulnar Nerve Roots: C8 and T1. Motor Functions: Innervates the muscles of the hand (apart from the thenar muscles and two lateral lumbricals), flexor carpi ulnaris and medial half of flexor digitorum profundus. Sensory Functions: Innervates the anterior and posterior surfaces of the medial one and half fingers, and associated palm area. Upper Brachial Plexus Injury (Erb’s Palsy) Erb’s palsy refers to an injury to the upper roots of the brachial plexus (typically C5-6). It most commonly occurs as a result of a stretching injury during a difficult vaginal delivery. Nerves affected – the peripheral nerves derived from C5-6 roots are most affected. This includes the musculocutaneous, axillary, suprascapular, and nerve to subclavius. Muscles affected – supraspinatus, infraspinatus, subclavius, biceps brachii, brachialis, coracobrachialis, deltoid and teres minor.  Motor functions affected – abduction at shoulder, lateral rotation of arm, supination of forearm, and flexion at shoulder. Sensory functions affected – sensation over the lateral aspect of upper limb (C5-6 dermatomes). The affected limb hangs limply, medially rotated by the unopposed action of pectoralis major. The forearm is pronated due to the loss of biceps brachii. The wrist is weakly flexed due to the normal tone of the wrist flexors relative to the weakened wrist extensors. This is position is known as ‘waiter’s tip’ and is characteristic of Erb’s palsy. Lower Brachial Plexus Injury (Klumpke’s Palsy) Klumpke’s palsy is an injury of the lower roots of the brachial plexus (C8-T1). It is also most commonly associated with a difficult vaginal delivery but has a much lower incidence than Erb’s palsy.  Nerves affected – the peripheral nerves derived from T1 root are most affected; the ulnar and median nerves Muscles affected – the intrinsic hand muscles Sensory functions affected – sensation along medial side of upper limb (C8-T1 dermatomes). The primary feature of Klumpke’s palsy is a clawed hand. This occurs due to paralysis of the lumbrical muscles, which normally act to flex the metacarpophalangeal joints (MCPJs) and extend the interphalangeal joints (IPJs). When paralysed, the fingers subsequently become extended at the MCPJs and flexed at the IPJs, producing a clawed appearance.  The 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. Borders The ulnar canal is approximately 4cm in length. It extends from the proximal aspect of the pisiform bone to the origin of the hypothenar muscles at the hook of hamate. Its borders consist of: Medial (ulnar) – pisiform, flexor carpi ulnaris tendon, abductor digiti minimi muscle. Lateral (radial) – hook of hamate. Roof – palmar carpal ligament. Floor – flexor retinaculum, pisohamate ligament, and hypothenar muscles. Contents The ulnar canal conveys the ulnar neurovascular bundle into the hand: Ulnar nerve – bifurcates within the canal into superficial (sensory) and deep (motor) branches. Ulnar artery – located on the radial aspect of the ulnar nerve. It gives rise to a deep palmar branch and continues laterally across the palm as the superficial palmar arch. Venae comitantes of ulnar artery Lymphatic vessels  The Carpal Tunnel The carpal tunnel is a narrow passageway found on the anterior portion of the wrist. It serves as the entrance to the palm for several tendons and the median nerve. Borders The carpal tunnel is formed by two layers: a deep carpal arch and a superficial flexor retinaculum. The deep carpal arch forms a concave surface, which is converted into a tunnel by the overlying flexor retinaculum (transverse carpal ligament). Carpal Arch Concave on the palmar side, forming the base and sides of the carpal tunnel. Formed laterally by the scaphoid and trapezium tubercles Formed medially by the hook of the hamate and the pisiform Flexor Retinaculum Thick connective tissue which forms the roof of the carpal tunnel. Turns the carpal arch into the carpal tunnel by bridging the space between the medial and lateral parts of the arch. Spans between the hook of hamate and pisiform (medially) to the scaphoid and trapezium (laterally). Contents The carpal tunnel contains a total of 9 tendons, surrounded by synovial sheaths, and the median nerve. The palmar cutaneous branch of the median nerve is given off prior to the carpal tunnel, travelling superficially to the flexor retinaculum. Tendons The tendon of flexor pollicis longus Four tendons of flexor digitorum profundus Four tendons of flexor digitorum superficialis The 8 tendons of the flexor digitorum profundus and flexor digitorum superficialis are surrounded by a single synovial sheath. The tendon of flexor pollicis longus is surrounded by its own synovial sheath. These sheaths allow free movement of the tendons. Median Nerve Once it passes through the carpal tunnel, the median nerve divides into 2 branches: the recurrent branch and palmar digital nerves. The palmar digital nerves give sensory innervation to the palmar skin and dorsal nail beds of the lateral three and a half digits. They also provide motor innervation to the lateral two lumbricals. The recurrent branch supplies the thenar muscle group.  The Anatomical Snuffbox The anatomical snuffbox (also known as the radial fossa), is a triangular depression found on the lateral aspect of the dorsum of the hand. It is located at the level of the carpal bones, and best seen when the thumb is extended. Borders As the snuffbox is triangularly shaped, it has three borders, a floor, and a roof: Ulnar (medial) border: Tendon of the extensor pollicis longus. Radial (lateral) border: Tendons of the extensor pollicis brevis and abductor pollicis longus. Proximal border: Styloid process of the radius. Floor: Carpal bones; scaphoid and trapezium. Roof: Skin. Contents The main contents of the anatomical snuffbox are the radial artery, a branch of the radial nerve, and the cephalic vein: Radial artery – crosses the floor of the anatomical snuffbox, then turns medially and travels between the heads of the adductor pollicis muscle. – The radial pulse can be palpated in some individuals by placing two fingers on the proximal portion of the anatomical snuffbox. Superficial branch of the radial nerve – found in the skin and subcutaneous tissue of the anatomical snuffbox. It innervates the dorsal surface of the lateral three and half digits, and the associated area on the back of the hand. Cephalic vein – arises from the dorsal venous network of the hand and crosses the anatomical snuffbox to travel up the anterolateral aspect of the forearm.  THE AXILLA REGION Description: The axilla is the name given to an area that lies underneath the glenohumeral joint, at the junction of the upper limb and the thorax. It is a passageway by which neurovascular and muscular structures can enter and leave the upper limb It consists of four sides, an open apex and base  AXILLA CONT… Borders: Apex – also known as the axillary inlet, it is formed by lateral border of the first rib, superior border of scapula, and the posterior border of the clavicle. Lateral wall – formed by intertubercular groove of the humerus. Medial wall – consists of the serratus anterior and the thoracic wall (ribs and intercostal muscles). Anterior wall – contains the pectoralis major and the underlying pectoralis minor and the subclavius muscles. Posterior wall – formed by the subscapularis, teres major and latissimus dorsi. N.B: The size and shape of the axilla region varies with arm abduction. The apex decreases in size most markedly when the arm is fully abducted – leaving the contents of the axilla at risk of compression.  CONTENT OF AXILLA Axillary artery (and branches) – the main artery supplying the upper limb. Axillary vein (and tributaries) – the main vein draining the upper limb, its two largest tributaries are the cephalic and basilic veins. Brachial plexus (and branches) – a collection of spinal nerves that form the peripheral nerves of the upper limb. Axillary lymph nodes – they filter lymphatic fluid that has drained from the upper limb and pectoral region. Axillary lymph node enlargement is a non-specific indicator of breast cancer. Biceps brachii (short head) and coracobrachialis – these muscle tendons move through the axilla, where they attach to the coracoid process of the scapula. PASSAGEWAYS OF EXISTING AXILLA; Quadrangular space: This is a gap in the posterior wall of the axilla, allowing access to the posterior arm and shoulder area. Structures passing through include the axillary nerve and posterior circumflex humeral artery (a branch of the axillary artery). Clavipectoral triangle: Is an opening in the anterior wall of the axilla. It is bounded by the pectoralis major, deltoid, and clavicle. The cephalic vein enters the axilla via this triangle, while the medial and lateral pectoral nerves leave CLINICAL IMPORTANCE OF AXILLA Thoracic outlet syndrome Lymph node biopsy  BREAST DESCRIPTION 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. BREAST SURFACE ANATOMY 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. At the center of the breast is the nipple, composed mostly of smooth muscle fibres. Surrounding the nipple is a pigmented area of skin termed the areolae. There are numerous sebaceous glands within the areolae.  ANATOMY OF BREAST The breast is composed of mammary glands surrounded by a connective tissue stroma. Mammary Glands The mammary glands are modified sweat glands. They consist of a series of ducts and secretory lobules (15-20). Each lobule consists of many alveoli drained by a single lactiferous duct. These ducts converge at the nipple like spokes of a wheel. Connective Tissue Stroma The connective tissue stroma is a supporting structure which surrounds the mammary glands. It has a fibrous and a fatty component.  ANATOMY OF BREAST Pectoral Fascia 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 OF THE BREAST 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- originate from axillary artery Thoracoacromial branch – 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. The veins of the breast correspond with the arteries, draining into the axillary and internal thoracic veins.  LYMPHATIC DRAINAGE OF THE BREAST 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.  BREAST NERVE SUPPLY 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 fibers CLINICAL RELEVANCE BREAST CANCER: Common presentations associated with breast cancer are due to blockages of the lymphatic drainage. Excess lymph builds up in the subcutaneous tissue, resulting in clinical features such as nipple deviation and retraction, and prominent skin between small dimpled pores