Upper Extremity.docx

34 Pages
Unlock Document

Anatomy and Cell Biology
Anatomy and Cell Biology 3319
Kem Rogers

Upper Extremity Pg. 186-194 & 298-314 Lab Notes: Pectoral Girdle • Shoulder girdle • Consists of clavicle (anteriorly) and scapula (posteriorly) • Paired pectoral girdles and their associated muscles form the shoulders • Girdle implies a belt completely circling the body – but these girdles do not satisfy this description: o Anteriorly –medial end of each clavicle joins to the sternum & first rib o Lateral ends of the clavicles join to the scapulae at the shoulder o Two scapulae fail to complete the ring posteriorly, because their medial borders do not join to each other or the axial skeleton • Attaches upper limb to trunk & provides attachment for many muscles that move the limb • Girdle is light & allows the upper limbs to be quite mobile • Mobility results from two factors o Because only clavicle attaches to axial skeleton, scapula can move quite freely across thorax, allowing the arm to move with it o Socket of shoulder joint – scapula’s glenoid cavity – is shallow so it does not restrict movement of humerus (arm bone) o Although arrangement is good for flexibility, it’s bad for stability: shoulder dislocations are common Clavicles • Collar bones • Slender, S-shaped bones that extend horizontally across the superior thorax on the anterior surface • Cone-shaped sternal end attaches to manubrium medially & flattened acromial end articulates with scapula laterally • Medial 2/3 of clavicle is convex anteriorly; can feel anterior protection when you palpate clavicle • Lateral third is concave anteriorly • Superior surface is almost smooth • Inferior surface is ridged & grooved for ligaments & muscles that attach clavicle to rib cage & scapula • Thick trapezoid line & conoid tubercle near acromial end - attachment for ligament that runs to scapula’s coracoid process • Rough area near sternal end is attachment site of costoclavicular ligament – connects clavicle to 1 rib • Functions: provide attachment for muscles, act as braces that hold scapulae & arms out laterally from thorax • Function becomes obvious when clavicle is fractured: entire shoulder collapses medially • Clavicles also transmit compression forces from upper limbs to axial skeleton (Ex. both arms pushes a car) • Fractures of the clavicle o Clavicles are not very strong and they often fracture o Can occur when person falls on lateral border of shoulder, is hit directly on clavicle in contact spot or uses outstretched arms to break a fall o Fractured clavicle is common injury in automobile accidents where occupants are wearing seat belts o Curves in clavicle ensure that it usually fractures anteriorly (outward) at its middle third o If it were to fracture posteriorly (inward), bone splinters would pierce main blood vessels to arm, subclavian vessels – lie just deep to clavicle Scapulae • Thin, triangular flat bones located on dorsal surface of the rib cage, between ribs 2 & 7 inferiorly • Each scapula has 3 borders: o Superior border  Shortest & sharpest o Medial border or vertebral border  Parallels the vertebral column o Thick lateral border or axillary border  Abuts the axilla (armpit) and ends superiorly in a shallow fossa: glenoid cavity  Cavity articulates with the humerus, forming the shoulder joint • Like all triangles – has three corners or angles o Glenoid cavity lies at lateral angle o Superior angle is where the superior & medial borders meet o Inferior angle is at the junction of the medial & lateral borders • Inferior angle moves as arm is raised & lowered – important landmark for studying scapular movements • Anterior or costal surface of the scapula is slightly concave & relatively featureless • Coracoid process o Projects anteriorly from lateral part of the superior scapular border o Root corac means like crow’s beak – but process looks like a bent finger o Attachment point for biceps of the arm o Strong ligaments also bind it to the clavicle • Just medial to coracoid process lies suprascapular notch (passageway for suprascapular nerve) • Lateral to coracoid process lies the glenoid cavity • Posterior surface bears a prominent spine that is easily felt through skin • Spine ends laterally in flat projection: acromium (apex of shoulder) –articulates with acromial end of clavicle • Several large fossae occur on both surfaces of scapula and are named according to location • Infraspinous fossae (below the spine) • Supraspinous fossae (above the spine) • Subscapular (under scapula) fossa is shallow concavity formed by entire anterior surface of scapula • Lying within Movements of Scapula these fossae are 1) Elevation (shrugging) & Depression muscles: 2) Protraction (punching) & Retraction (standing at attention) 3) Upward & Downward Rotation (moving arms over head & down again) infraspinatus, supraspinatus & subcapularis Posterior Thorax Levator Scapulae Trapezius Rhomboid (Major & Minor) Anterior Thorax Pectoralis Minor Serratus Anterior (Boxer’s Muscle) Subclavius  Stabilize and depress pectoral girdle  Extending from rib 1 to clavicle  O – costal cartilage of rib 1  I – groove on inferior surface of clavicle  Nerve to subclavius (C5 & C6) Rotator Cuff Muscles • 4 muscles that originate on the scapula and cross the shoulder joint to insert on the humerus • All encircle shoulder joint (cuff) & help to anchor head of humerus into glenoid cavity of shoulder joint • Some (3/4) act to rotate humerus (either medially or laterally); one (supraspinatus) acts to abduct arm • Supraspinatus, Teres Minor, Infraspinatus insert into greater tubercle of humerus • Subscapularis, inserts into lesser tubercle The Upper Limb • 30 bones form the skeleton of the upper limb - grouped into bones of the arm, forearm & hand Arm • Arm or brachium to designate part of the upper limb between shoulder & elbow only • Humerus is the only bone of the arm - largest and longest bone in the upper limb • Articulates with the scapula at the shoulder and with radius & ulna (forearm bones) at the elbow • At the proximal end of the humerus is hemispherical head – fits into glenoid cavity of scapula • Just inferior to head is a slight constriction, anatomical neck • Inferior to neck is lateral greater tubercle & more medial lesser tubercle separated by intertubercular sulcus or bicipital groove • Tubercles are sites of attachment for the rotator cuff muscles • Intertubercular sulcus guides at tendon of biceps to its attachment point at rim of glenoid cavity (supraglenoid tubercle) • Surgical neck of the humerus (most frequently fractured) is inferior to tubercles • About midway down the shaft on the lateral side, is the deltoid tuberosity o V-shaped roughened area is an attachment site for the deltoid muscle of the shoulder • Near deltoid tuberosity along posterior surface of shaft, radial groove descends obliquely – radial nerve • At the distal end of humerus are two condyles o Medial trochlea that articulates with the ulna – looks like an hourglass turned on its side o Lateral capitulum that articulates with the radius – looks like a half ball • Condyles are flanked by medial & lateral epicondyles - attachment sites for muscles of the forearm • Directly above epicondyles are medial & lateral supracondylar ridges • On posterior surface of the humerus directly proximal to trochlea is the deep olecranon fossa • Corresponding position on anterior surface is shallower coronoid fossa medially & radial fossa laterally • Fossae receive similarly named projections of the forearm bones during forearm movement Glenohumeral Joint: Shoulder Joint Dislocation of the Shoulder • Due to ill-fitted glenohumeral joint, shoulder is the most common form of dislocation accounting for about 85% of all dislocations • Most dislocations are in the anterior plane, but they can also occur posteriorly, or inferiorly Forearm • Forearm or antebrachium • 2 parallel long bones: radius & ulna • Articulate with humerus proximally and the bones of the wrist distally • Radius & ulna also articulate with each other both proximally and distally at the small radioulnar joints • Radius & ulna are interconnected along their entire length by flat ligament called interosseous membrane (between the bones) • In anatomical position, radius lies laterally (on the thumb side) and ulna medially • However, when palm faces posteriorly, distal end of radius crosses over ulna & two bones form an X Ulna • Slightly longer than the radius • Main bone forming the elbow joint with the humerus • Looks like a money wrench • At its proximal end are 2 prominent projections: olecranon (elbow) & coronoid (crown-shaped) process – separated by a deep concavity: trochlear notch • Together, 2 processes grip trochlea of humerus forming a hinge joint that allows forearm to bend upon arm (flex) and then straighten again (extend) • When forearm is fully extended – olecranon process “locks” into olecranon fossa of the humerus • When forearm is flexed, coronoid process of the ulna fits into the coronoid fossa of the humerus • On lateral side of coronoid process is smooth depression: radial notch – head of radius articulates with ulna • Distally, shaft of ulna narrows & ends in a knoblike head that articulates with the radius • Medial to this is ulnar styloid process – from which ligament runs to the wrist • Head of ulna is separated from wrist bones by disc of fibrocartilage & plays little/no role in hand movements Radius • Thin at its proximal end and widened at tis distal end – opposite of ulna • Proximal head is shaped like the end of a spool of thread • Superior surface is concave – articulates with the capitulum of humerus • Medially, head of radius articulates with radial notch of ulna – forming proximal radioulnar joint • Just distal to head, on anterior surface in anatomical position, is a rough bump: radial tuberosity o Site of attachment of the biceps • On distal end of radius – medial ulnar notch articulates with head of ulna – distal radioulnar joint • Lateral radial styloid process anchors a ligament that runs to the wrist • Distal articular surface is concave and articulates with carpal bones of the wrist • Whereas ulna contributes a lot to elbow joint – radius is primary forearm bone contributing to wrist joint • When the radius rotates – hand moves with it • Distal, knob-like radial & ulnar styloid processes can be palpated by grasping dorsal side of distal forearm adjacent to the wrist with the thumb and index finger of the opposite hand • In this position, thumb palpates radial styloid process & index finger palpates the ulnar styloid process • Radial styloid process lies about 1 cm (0.4 inch) distal to ulnar styloid process Clinical Application - Palpation of Colles’ Fracture • Cause: fallen on outstretched hand & wrist has curves that resemble a fork • Clinician palpates for the position of the styloid processes • If palpation reveals that styloid process of radius has moved proximally from its normal position • Impacted fracture in which the distal end of the radius is forced proximally into shaft of radius Hand • Skeleton of hand includes: bones of carpus (wrist), bones of metacarpus (palm) & phalanges (fingers) Carpus • True wrist or carpus is the proximal region of the heand, just distal to the wrist joint • Contains 8 marble-sized short bones or carpals – closely united by ligaments • Gliding movements occurs between carpals, making wrist rather flexible • Carpals are arranged in two irregular rows of four bones each • In proximal row, from lateral (thumb side) to medial: scaphoid (boat-shaped), lunate (moonlike), triquetrum (triangular), & pisiform (pea-shaped) bones • Only scaphoid and lunate bones articulate with radius to form the wrist joint • In distal row, from lateral to medial: trapezium (little table), trapezoid (four-sided), capitate (head- shaped) & hamate (hooked) bones Some Lovers Try Positions That They Can’t Handle • Scaphoid is the most frequently fractured – often result from falling on an outstretched hand • Impact bends the scaphoid, which then breaks at its narrow midregion Metacarpus • Five metacarpals radiate distally from the wrist to form the metacarpus or palm • Small long bones are not named individually but instead are numbered I to V from thumb to little finger • Bases of metacarpals articulate with carpals proximally & with each other on their lateral & medial sides • Distally, bulbous heads of the metacarpals articulate with the proximal phalanges to form the knuckles • Metacarpal I, associated with the thumb – is the shortest and most mobile Phalanges of the Fingers • Digits or fingers – numbered I to v beginning with the thumb or pollex • Fingers contain miniature long bones called phalanges (singular phalanx) • In post people – third finger is the longest • With the exception of the thumb – each finger has three phalanges: proximal, middle & distal • Thumb has no middle phalanx Clinical Application – Carpal Tunnel Syndrome • Flexor retinaculum (transverse carpal ligament) lies distal to radial joint, spans across carpal bones, forming tunnel through which flexor tendons & median nerve pass (innervates lateral ½ of hand including muscles of thumbs • Functionally, retinaculum prevents “bowstringing” of these tendons during contraction of flexors • Inflammation of anything in tunnel – ex. tendons swollen from overuse, can compress median nerve • Nerve impairment affects workers who repeatedly flex wrists & fingers • High risk: using vibrating tools for long time, assembly worker, workers in food processing & packaging • Nerve impairment causes skin of lateral part of hand to tingle or numb & thumb movements to weaken • Followed by dull pain in affected area – can spread up to shoulders & neck • Condition can be treated by resting hand in splint during sleep, anti-inflammatory drugs & surgery • Carpal tunnel syndrome is just one example of a repetitive stress injuries Muscles of Upper Limb: Shoulder & Arm Anterior Muscles of Arm Pectoralis Major • Origin: o Clavicular head: anterior surface of medial ½ of clavicle o Sternocostal head: anterior surface of sternum, superior 6 costal cartilages, aponeurosis of external oblique • Insertion: lateral lip of intertubercular groove of humerus • Action: flexion, adduction, medial rotation of shoulder • Innervation: lateral and medial pectoral nerves Coracobrachialis • Origin: tip of coracoid process of scapula • Insertion: middle 1/3 of medial humerus • Action: flexes and Adducts arm • Innervation: musculocutaneuos nerve (C5,C6,C7) ________________________________________________________________________________________ Posterior Muscles of Arm Teres Major • Origin: dorsal surface of inferior angle of scapula • Insertion: intertubercular groove of humerus • Action: Extends, adducts and medially rotates arm • Innervation: lower subscapular nerve (C6,C7) Latissimus Dorsi • Origin: spinous processes of inferior 6 thoracic vertebrae; thoracolumbar fascia, iliac crest & inferior 3-4 ribs • Insertion: intertubercular groove of humerus • Action: Extends, adducts and medially rotates shoulder • Innervation: thoracodorsal nerve (C6,C7, C8) ________________________________________________________________________________________ Deltoid • Origin: lateral 1/3 of clavicle, acromium & spine of scapula • Insertion: Deltoid tuberosity of humerus • Action: o Anterior fibers: flexes & medially rotates arm o Middle fibers: abducts arm o Posterior fibers: extends and laterally rotates arm • Innervation: axillary nerve (C5, C6) Compart
More Less

Related notes for Anatomy and Cell Biology 3319

Log In


Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.