Lab 7 Upper Limb PDF

Lab 7: Upper Limb Skeleton Resources: Articulated skeletons, disarticulated bones, skeletal chart Atlas plates: 276-283, 304-306, 310, 322-323 Pectoral Girdle Clavicle Scapula Sternal end Me...

Lab 7: Upper Limb Skeleton Resources: Articulated skeletons, disarticulated bones, skeletal chart Atlas plates: 276-283, 304-306, 310, 322-323 Pectoral Girdle Clavicle Scapula Sternal end Medial border Acromial end Lateral border Spine Supraspinous fossa Infraspinous fossa Acromion process Coracoid process Glenoid fossa Arm (Brachium) Forearm (Antebrachium) Wrist/Hand Humerus Ulna Carpals Head Coronoid process Scaphoid Greater tubercle Olecranon process Lunate Crest of greater tubercle Ulnar tuberosity Triquetrum Lesser tubercle Styloid process Pisiform Crest of lesser tubercle Trochlear notch Trapezium Intertubercular groove Radial notch Trapezoid Deltoid tuberosity Capitate Medial supracondylar Radius Hamate crest Head Lateral supracondylar Neck Metacarpals crest Radial tuberosity Medial epicondyle Styloid process Phalanges Lateral epicondyle Proximal Trochlea Middle Coronoid fossa Distal Capitulum Radial fossa Olecranon fossa Upper Limb Articulations/Joints Resources: Your body, articulated skeletons, skeleton chart Atlas Plates: 282-285 57 The synovial, ball-and-socket glenohumeral (shoulder) joint is highly mobile and relatively unstable because the glenoid fossa of the scapula, the “socket” with which the head of the humerus articulates, is very shallow and thus provides little structural stability. The head of the humerus is held in the shallow glenoid fossa by the contraction of the rotator cuff muscles, i.e., subscapularis, supraspinatus, infraspinatus and teres minor. The shoulder joint is most commonly dislocated anteriorly. The contraction of multiple additional muscles, e.g., the coracobrachialis, short head of the biceps brachii, long head of the triceps brachii and the deltoid, all help to resist inferior dislocation. The elbow is a synovial hinge joint. The articular capsule of this joint is strengthened medially and laterally by fan-like ligaments. The wrist joint is a condyloid synovial joint. A condyloid joint is biaxial, allowing movement in two planes, sagittal and coronal. Thus, the wrist joint can be flexed/extended and adducted/abducted. The distal ends of the radius and ulna articulate with the proximal carpal bones except for the pisiform. The fibrous capsule is strengthed by numerous palmar (ventral) and dorsal ligaments. Upper Limb Muscle Actions Resources: Your body, articulated skeletons Atlas Plates: None Muscle Action Description Flexion movement that decreases the angle between body parts at a joint(s) Extension movement that increases the angle between body parts at a joint(s) Lateral flexion lateral movement of trunk in coronal plane Abduction lateral movement of a body part away from the midline Adduction medial movement of a body part toward the midline Rotation limb segment pivots around the longitudinal axis of the limb Medial rotation rotation of the anterior surface of a limb medially Lateral rotation rotation of the anterior surface of a limb laterally Supination rotation of forearm and hand laterally so the palm faces anteriorly Pronation rotation of forearm and hand medially so the palm faces posteriorly Elevation movement of a body part superiorly (e.g. scapula) Depression movement of a body part inferiorly (e.g. scapula) Protraction movement of body part anteriorly (e.g. scapula) Retraction movement of a body part posteriorly (e.g. scapula) 58  Thumb abduction movement of the thumb anteriorly in a direction perpendicular to the palm Thumb adduction movement of the thumb posteriorly Thumb opposition touching the pad of the thumb to the pad of another finger Upper Limb Muscles Resources: upper limb models, mini-man model, muscle chart, cadavers, display images Phayrngeal Group Note: pharyngeal muscles are voluntary, skeletal muscles that are derived from the pharyngeal arches of the neck (not from somites). We will be studying the pharyngeal arch muscles in the third unit of the course. We take up two pharyngeal arch muscles here because they have upper limb actions. Atlas Plates: 288, 292, 300 Muscle Origin Insertion Action Innervation Sternocleidomastoid Manubrium of Mastoid process of Bilateral action: flex sternum & skull head & neck medial clavicle Unilateral action: laterally flex head & neck Trapezius Occipital bone Spine & acromion Superior fibers: Accessory n. & spinous process of scapula, elevate scapula (as processes of lateral clavicle in shrugging) cervical & thoracic Middle fibers: vertebrae retract scapula Inferior fibers: depress scapula Serratus Group Atlas Plates: 293, 295, 299-300 Muscle Origin Insertion Action Innervation Serratus anterior Outer surfaces of Medial border of protract and ribs scapula depress scapula Rhomboideus Spinous Medial border of Elevate & processes of scapula (dorsal retract scapula Brachial plexus vertebrae C7 – T5 to serratus anterior) Levator scapulae Transverse Medial border of Elevate scapula processes of scapula (superior Extend neck vertebrae C1 – C4 to rhomboideus when scapula muscle fixed 59 Latissimus Group Atlas Plates: 290-295, 297, 301, Muscle Origin Insertion Action Innervation Latissimus dorsi Spinous processes Intertubercular of inferior 6 groove Extend, thoracic adduct & vertebrae, medially rotate Brachial Plexus thoracolumbar humerus fascia, iliac crest, inferior 3 ribs Teres major Lateral border of Crest of lesser scapula tubercle Subscapularis Ventral surface of Lesser tubercle Adduct, (rotator cuff m.) scapula medially rotate humerus Deltoid Group Atlas Plates: 288, 291-297 Muscle Origin Insertion Action Innervation Deltoideus Acromion Deltoid Anterior fibers: process, spine of tuberosity flex, adduct & scapula, lateral medially rotate clavicle humerus Middle fibers abduct humerus Axillary n Posterior fibers extend, adduct & laterally rotate humerus Teres minor Lateral border of Posterior greater Adduct & (rotator cuff m.) scapula tubercle laterally rotate humerus Pectoral Group Atlas Plates: 288-289, 298-299 Muscle Origin Insertion Action Innervation Pectoralis major Sternum, costal Crest of greater Adduct, flex & cartilages, and tubercle medially rotate medial clavicle humerus Brachial plexus Pectoralis minor Ribs 3-5 Coracoid process Depress & protract scapula 60 Spinatus Group Atlas Plates: 293-295, 297 Muscle Origin Insertion Action Innervation Supraspinatus Supraspinous Superior greater Abduct humerus (rotator cuff m.) fossa tubercle Brachial plexus Infraspinatus Infraspinous fossa Posterior greater Adduct & (rotator cuff m.) tubercle laterally rotate humerus Triceps Group Atlas Plates: 292-295, 298, 303, Muscle Origin Insertion Action Innervation Triceps brachii Long head: Olecranon Extend forearm inferior glenoid process Extend humerus tubercle Medial & Lateral Extend forearm Radial n heads: posterior surface of humerus Brachial Group Atlas Plates: 288-291, 302 Muscle Origin Insertion Action Innervation Coracobrachialis Coracoid Medial surface of Adduct, flex & process humerus medially rotate humerus Brachialis Anterior surface Coronoid Flex forearm of humerus process & ulnar tuberosity Musculocutaneous n Biceps brachii Long head: Radial Flex and superior glenoid tuberosity Supinate forearm tubercle Flex humerus Short head: Flex and coracoid supinate process forearm 61 Flexor Forearm Muscles Atlas Plates: 312-313, 316-317 Muscle Origin Insertion Action Innervation Superficial Layer Pronator teres Lateral radius Pronate forearm Flexor carpi Base of Flex hand radialis Medial epicondyle metacarpals 2 & 3 Abduct hand Median n Palmaris longus of humerus Palmar Flex hand aponeurosis Flexor carpi Base of Flex hand Ulnar n ulnaris metacarpal 5, Adduct hand hamate, & pisiform Intermediate Layer Flexor digitorum Medial epicondyle Middle phalanges Flex hand Median nerve superficialis of humerus & of fingers 2-5 Flex fingers superior half of anterior radius Deep Layer Flexor digitorum Anterior ulna and Distal phalanges Flex hand Median & Ulnar profundus interosseous of fingers 2-5 Flex fingers nn membrane Flexor pollicis Anterior radius Distal phalanx of Flex hand longus and interosseous thumb Flex thumb membrane Median n Pronator Distal ulna Distal radius Pronate forearm quadratus 62 Extensor Forearm Muscles Atlas Plates: 314-315, 318-321 Muscle Origin Insertion Action Innervation Superficial Layer Brachioradialis Lateral Styloid process Flex forearm supracondylar of radius crest of humerus Extensor carpi Lateral Base of Extend hand radialis longus supracondylar metacarpal 2 Abduct hand crest & lateral epicondyle of humerus Extensor carpi Base of Extend hand radialis brevis metacarpal 3 Abduct hand Extensor Lateral epicondyle Distal phalanges Extend hand digitorum of humerus of fingers 2-5 Extend fingers Extensor digiti Distal phalanx of Extend hand Radial n minimi finger 5 Extend digit 5 Extensor carpi Lateral epicondyle Base of Extend hand ulnaris of humerus & metacarpal 5 Adduct hand posterior ulna Deep Layer Supinator Lateral epicondyle Posterior, lateral Supinate of humerus & and anterior forearm olecranon one-third of radius Abductor pollicis Posterior radius, Base of Abduct thumb longus ulna, & metacarpal 1 Abduct hand interosseus membrane Extensor pollicis Posterior radius & Proximal phalanx Extend proximal brevis interosseus of thumb phalanx of membrane (distal thumb to APL) Abduct hand Extensor pollicis Posterior ulna & Distal phalanx of Extend distal longus interosseus thumb phalanx of membrane thumb Extend hand Extensor indicis Posterior ulna & Posterior surface Extend index interosseus of index finger finger membrane (distal Extend hand to EPL) Intrinsic Hand Muscles You will recall that the big toe of the foot is in line with the other toes and therefore is non opposable. Now notice that the thumb, the upper limb homolog of the big toe, is rotated out of the plane of fingers 2-5 and therefore is opposable, i.e., adapted for grasping. Our evolutionary cousins, the great apes, also have opposable thumbs. However, the human thumb is much larger, more 63 mobile and therefore fully opposable. In addition, the human fingers and palm are shorter than in other great apes. As a result, we can touch the thumb to each of the other fingers and to the palm of the hand. The great apes have a much shorter, less mobile thumb and longer fingers and palm. Therefore, the great ape thumb can touch the lateral surface of the index finger when digits 2-5 are flexed around an object but cannot be brought into opposition with the tips of the fingers and the palm. Human thumb opposition is important for gripping and effectively manipulating both spheres (baseballs) and cylinders (baseball bats). The act of opposition is complex and requires multiple thumb actions, which, in sequence, are extension, abduction, flexion, medial rotation and finally adduction. We ask you to be able to identify and know the actions and innervations of the four intrinsic hand muscles in the Thenar group. Along with the three deep forearm muscles that act on the thumb, these muscles collectively produce opposition. Note that three of these muscles are innervated by the median nerve so when that nerve is inoperable, thumb opposition isn’t possible. Thenar Muscle Group Atlas Plates: 334-337 Muscle Action Innervation Abductor pollicis brevis Abducts thumb Median n. Flexor pollicis brevis Flexes thumb Opponens pollicis Medially rotates thumb bringing it into opposition with center of palm Adductor pollicis Adducts thumb toward middle digit Ulnar n. Superior Limb Blood Supply & Nerves Blood Vessels Resources: Nervous and circulatory chart, upper limb models, display images, cadavers Arteries Atlas plates: 344-345, 349, 363, 366-369 The lateral continuation of the subclavian artery is the axillary artery and its borders are the first rib and the teres major muscle. It passes deep to the pectoralis minor muscle as it runs through the axilla. Branches of the axillary artery supply blood to the skin of the shoulder and axilla, the mammary gland, and shoulder muscles. The continuation of the axillary artery is the brachial artery. It runs through the arm (brachium) on the medial side of the humerus. Branches of the brachial artery supply the muscles and skin of the upper arm, or brachium. Just proximal to the elbow, in the cubital fossa, the brachial artery divides into the radial and ulnar arteries. 64  The radial artery travels to the forearm deep to the brachioradialis muscle. It supplies skin and muscles of the anterolateral forearm, lateral wrist, thumb, and index finger. The ulnar artery descends along the medial side of the anterior forearm between the superficial and deep flexor muscles. It supplies the skin and muscles of the anteromedial forearm, medial wrist, and digits 3-5. Both arteries join in the palm to form palmar arches. Digital arteries extend to the fingers from these palmar arches. Veins Atlas plates: 346, 358, 362-365 The upper limb is drained by deep and superficial veins. The deep veins include the radial, ulnar, brachial, and axillary veins. They follow the paths of the arteries of the same name. The superficial veins form complex vascular networks just beneath the skin. The primary veins of this network are the basilic and cephalic veins. The basilic vein ascends along the medial forearm and the medial arm to drain into the brachial vein. The cephalic vein ascends laterally along the forearm and arm to drain into the axillary vein just inferior to the clavicle. Nerves: The Brachial Plexus Resources: Nervous and circulatory chart, upper limb models, display images, cadavers Atlas plates: 348-349, 352-357, 361, 363-366, 368-369 Innervation of the muscles and skin of the shoulder, arm, forearm and hand is provided by branches of the brachial plexus. The brachial plexus is formed from ventral rami of spinal nerves C5-8 and T1. From proximal to distal, the components of the brachial plexus include: 5 roots (please don't confuse brachial plexus roots [= ventral rami] with spinal dorsal roots!), 3 trunks, 3 anterior and 3 posterior divisions, 3 cords, and 5 terminal nerves. The roots of the brachial plexus (ventral rami of spinal segments C5-8 and T1) lie deep to the sternocleidomastoid. The roots of the plexus unite at the lateral border of the sternocleidomastoid muscle to form superior, middle, and inferior trunks. The superior trunk is formed from a union of ventral rami C5 and C6. The middle trunk is a continuation of ventral ramus C7. The inferior trunk is a fusion of C8 and T1 ventral rami. Each trunk subsequently divides into an anterior and posterior division whose fibers will ultimately innervate upper limb anterior and posterior muscle groups respectively. 65 After passing deep to the clavicle and entering the axilla, the anterior and posterior divisions unite to form the lateral, medial, and posterior cords. Nerve fibers of the lateral and medial cords are composed of anterior divisions and therefore will innervate anterior muscle groups. The posterior cord is made up of all the posterior divisions and will therefore supply posterior muscle groups. In the axilla, the lateral cord lies lateral to the axillary artery; the medial cord lies medial to it. The posterior cord lies posterior to the axillary artery. These three cords give rise to 5 primary nerves, all of which you are asked to identify on laboratory resources. The lateral cord contributes to two of the 5 nerves: the musculocutaneous nerve and the median nerve. The musculocutaneous nerve branches laterally and leaves the axilla by passing through the coracobrachialis muscle to the anterior brachium where it descends between, and innervates, the biceps brachii and brachialis muscles. Distally, the nerve emerges lateral to the biceps tendon as the lateral cutaneous nerve, which then courses down the forearm to provide anterolateral cutaneous innervation. The median nerve is formed by branches from the lateral and medial cords. o It descends anterolaterally along the axillary artery and brachial arteries, gradually crossing the brachial artery to lie medial to it at the elbow. o The median nerve enters the forearm on the anterior surface of the brachialis muscle. o It then descends deep to the flexor digitorum superficialis muscle. o Proximal to the wrist, the median nerve is located medially and passes deep to the tendons of the flexor digitorum superficialis muscle. It remains in this position as it runs out to the hand. o The median nerve supplies motor innervation to most muscles of the anterior (flexor) forearm and a few hand muscles. In addition to its contribution to the median nerve, the medial cord also gives rise to the ulnar nerve. The ulnar nerve descends into the arm posteromedial to the axillary artery. Near the middle of the arm, the ulnar nerve passes medial to the triceps brachii muscle and then passes posterior to the medial epicondyle into the forearm where it is just skin deep! (The “funny bone” sensation you get when banging your elbow is from the ulnar nerve.) The ulnar nerve then descends between, and innervates, the flexor carpi ulnaris and one-half of the flexor digitorum profundus muscle.. It passes onto the hand in the company of the ulnar artery close to the pisiform bone. The ulnar nerve innervates most of the intrinsic hand muscles. The posterior cord gives rise to the axillary and radial nerves. 66  The axillary nerve branches off laterally and travels towards the neck of the humerus where it innervates the deltoid group. The radial nerve is the continuation of the posterior cord. o It runs through the axilla posterior to the axillary artery. o After leaving the axilla, the radial nerve spirals posteriorly around the humerus in the radial groove, supplying motor innervation to the triceps group. o As the radial nerve passes onto the forearm between the lateral epicondyle and the brachioradialis muscle, it divides into superficial and deep branches. ▪ The deep branch passes to the posterior aspect of the forearm where it innervates the extensor muscles of the wrist and fingers. ▪ The superficial branch descends under the brachioradialis muscle (and lateral to the radius). It emerges on the back of the hand to supply cutaneous innervation to the dorsolateral surface of the hand. The following table summarizes the motor innervation provided by the nerves discussed above. Nerve Origin Motor Innervation Musculocutaneous Lateral Cord Brachial group muscles Median Lateral and Forearm flexor muscles (except for flexorum carpi ulnaris Medial Cords and medial half of flexor digitorum profundus) and 5 intrinsic hand muscles Ulnar Medial Cord Flexor carpi ulnaris, Medial half flexor digitorum profundus, Most intrinsic hand muscles except thenar muscles Axillary Posterior Cord Deltoid group muscles Radial Posterior Cord Triceps group muscles, Extensor forearm muscles These nerves, and others branching from the brachial plexus, also provide sensory innervation to the upper limb but we ask you to know only the motor innervation. 67