Muscles of the Pectoral Girdle and Upper Limbs _ Anatomy and Physiology I.pdf

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Unformatted text preview: 4/5/2021 Muscles of the Pectoral Girdle and Upper Limbs | Anatomy and Physiology I Anatomy and Physiology I Module 12: The Muscular System Muscles of the Pectoral Girdle and Upper Limbs … 1/22 4/5/2021 Muscles of the Pectoral Girdle and Upper Limbs | Anatomy and Physiology I LEARNING OBJECTIVES Identify the muscles of the pectoral girdle and upper limbs Identify the movement and function of the pectoral girdle and upper limbs Muscles of the shoulder and upper limb can be divided into four groups: muscles that stabilize and position the pectoral girdle, muscles that move the arm, muscles that move the forearm, and muscles that move the wrists, hands, and ngers. The pectoral girdle, or shoulder girdle, consists of the lateral ends of the clavicle and scapula, along with the proximal end of the humerus, and the muscles covering these three bones to stabilize the shoulder joint. The girdle creates a base from which the head of the humerus, in its ball-and-socket joint with the glenoid fossa of the scapula, can move the arm in multiple directions. Muscles That Position the Pectoral Girdle Muscles that position the pectoral girdle are located either on the anterior thorax or on the posterior thorax (Figure 1 and Table 1). Figure 1. Muscles That Position the Pectoral Girdle. The muscles that stabilize the pectoral girdle make it a steady base on which other muscles … 2/22 4/5/2021 Muscles of the Pectoral Girdle and Upper Limbs | Anatomy and Physiology I can move the arm. Note that the pectoralis major and deltoid, which move the humerus, are cut here to show the deeper positioning muscles. The anterior muscles include the subclavius, pectoralis minor, and serratus anterior. The posterior muscles include the trapezius, rhomboid major, and rhomboid minor. When the rhomboids are contracted, your scapula moves medially, which can pull the shoulder and upper limb posteriorly. … 3/22 4/5/2021 Muscles of the Pectoral Girdle and Upper Limbs | Anatomy and Physiology I Table 1. Muscles that Position the Pectoral Girdle Position in the Thorax Movement Target Target motion direction Prime mover Origi Anterior thorax Stabilizes clavicle during movement by depressing it Clavicle Depression Subclavius First Anterior thorax Rotates shoulder anteriorly (throwing motion); assists with inhalation Scapula; ribs Scapula: depresses; ribs: elevates Pectoralis minor Anter surfa of ce ribs ( or 3– Anterior thorax Moves arm from side of body to front of body; assists with inhalation Scapula; ribs Scapula: protracts; ribs: elevates Serratus anterior Musc slips certa ribs (1 or 1–9 Posterior thorax Elevates shoulders (shrugging); pulls shoulder blades together; tilts head backwards Scapula; cervical spine Scapula: rotates inferiorly, retracts, elevates, and depresses; spine: extends Trapezius Skull verte colum Posterior thorax Stabilizes scapula during pectoral girdle movement Scapula Retracts; rotates inferiorly Rhomboid major Thora verte (T2–T Posterior thorax Stabilizes scapula during pectoral girdle movement Rhomboid minor Cervi and thora verte (C7 a T1) Scapula Retracts; rotates inferiorly … 4/22 4/5/2021 Muscles of the Pectoral Girdle and Upper Limbs | Anatomy and Physiology I Muscles That Move the Humerus Similar to the muscles that position the pectoral girdle, muscles that cross the shoulder joint and move the humerus bone of the arm include both axial and scapular muscles (Figure 2, Figure 3, and Table 2). Figure 2. Muscles That Move the Humerus. The muscles that move the humerus anteriorly are generally located on the anterior side of the body and originate from the sternum (e.g., pectoralis major) or the anterior side of the scapula (e.g., subscapularis). Figure 3. Muscles That Move the Humerus. (b) The muscles that move the humerus superiorly generally originate from the superior surfaces of the scapula and/or the clavicle (e.g., deltoids). The muscles that move the humerus inferiorly generally originate from middle or lower back (e.g., latissiumus dorsi). (d) The muscles that move the humerus posteriorly are generally located on the posterior side of the body and insert into the scapula (e.g., infraspinatus). The two axial muscles are the pectoralis major and the latissimus dorsi. The pectoralis major is thick and fan-shaped, covering much of the superior portion of the anterior thorax. The broad, triangular latissimus … 5/22 4/5/2021 Muscles of the Pectoral Girdle and Upper Limbs | Anatomy and Physiology I dorsi is located on the inferior part of the back, where it inserts into a thick connective tissue shealth called an aponeurosis. … 6/22 4/5/2021 Muscles of the Pectoral Girdle and Upper Limbs | Anatomy and Physiology I Table 2. Muscles That Move the Humerus Movement Target Target motion direction Humerus Flexion; adduction; medial rotation Humerus; scapula Humerus: extension, adduction, and medial rotation; scapula: depression Prime mover Origin Pectoralis major Clavicle; sternum; cartilage of ribs (1–6 or 1–7); aponeurosis of external oblique muscle Latissimus dorsi Thoracic vertebrae (T7– T12); lumbar vertebrae; lower ribs (9– 12); iliac crest Deltoid Trapezius; clavicle; acromion; spine of scapula Subscapularis Subscapular fossa of the scapula Axial muscles Brings elbows together; moves elbow up (as during an uppercut punch) Moves elbow back (as in elbowing someone standing behind you); spreads elbows apart Scapular muscles Lifts arms at the shoulder Humerus Abduction; exion; extension; medial and lateral rotation Assists the pectoralis major in bringing the elbows together and stabilizes the shoulder joint during movement of the pectoral girdle Humerus Medial rotation … 7/22 4/5/2021 Muscles of the Pectoral Girdle and Upper Limbs | Anatomy and Physiology I Table 2. Muscles That Move the Humerus Movement Target Target motion direction Prime mover Origin Rotates the elbow outwards, as during a tennis swing Humerus Abduction Supraspinatus Supraspinous fossa of the scapula Rotates the elbow outwards, as during a tennis swing Humerus Extension; adduction Infraspinatus Infraspinous fossa of the scapula Assists the infraspinatus in rotating the elbow outwards Humerus Extension; adduction Teres major Posterior surface of the scapula Assists the infraspinatus in rotating the elbow outwards Humerus Extension; adduction Teres minor Lateral border of the dorsal scapular surface Moves the elbow up and across the body, as when putting a hand on the chest Humerus Flexion; adduction Coracobra chialis Coracoid process of the scapula The rest of the shoulder muscles originate on the scapula. The anatomical and ligamental structure of the shoulder joint and the arrangements of the muscles covering it, allows the arm to carry out di erent types of movements. The deltoid, the thick muscle that creates the rounded lines of the shoulder is the major abductor of the arm, but it also facilitates exing and medial rotation, as well as extension and lateral rotation. The subscapularis originates on the anterior scapula and medially rotates the arm. Named for their locations, the supraspinatus (superior to the spine of the scapula) and the infraspinatus (inferior to the spine of the scapula) abduct the arm, and laterally rotate the arm, respectively. The thick and at teres major is inferior to the teres minor and extends … 8/22 4/5/2021 Muscles of the Pectoral Girdle and Upper Limbs | Anatomy and Physiology I the arm, and assists in adduction and medial rotation of it. The long teres minor laterally rotates and extends the arm. Finally, the coracobrachialis exes and adducts the arm. The tendons of the deep subscapularis, supraspinatus, infraspinatus, and teres minor connect the scapula to the humerus, forming the rotator cu (musculotendinous cu ), the circle of tendons around the shoulder joint. When baseball pitchers undergo shoulder surgery it is usually on the rotator cu , which becomes pinched and in amed, and may tear away from the bone due to the repetitive motion of bring the arm overhead to throw a fast pitch. Muscles That Move the Forearm The forearm, made of the radius and ulna bones, has four main types of action at the hinge of the elbow joint: exion, extension, pronation, and supination. The forearm exors include the biceps brachii, brachialis, and brachioradialis. The extensors are the triceps brachii and anconeus. The pronators are the pronator teres and the pronator quadratus, and the supinator is the only one that turns the forearm anteriorly. When the forearm faces anteriorly, it is supinated. When the forearm faces posteriorly, it is pronated. The biceps brachii, brachialis, and brachioradialis ex the forearm. The two-headed biceps brachii crosses the shoulder and elbow joints to ex the forearm, also taking part in supinating the forearm at the radioulnar joints and exing the arm at the shoulder joint. Deep to the biceps brachii, the brachialis provides additional power in exing the forearm. Finally, the brachioradialis can ex the forearm quickly or help lift a load slowly. These muscles and their associated blood vessels and nerves form the anterior compartment of the arm (anterior exor compartment of the arm) (Figure 4 and Table 3). … 9/22 4/5/2021 Muscles of the Pectoral Girdle and Upper Limbs | Anatomy and Physiology I This multipart gure shows the di erent muscles that move the forearm. The major muscle groups are labeled. Figure 4. Muscles That Move the Forearm. The muscles originating in the upper arm ex, extend, pronate, and supinate the forearm. The muscles originating in the forearm move the wrists, hands, and ngers. … 10/22 4/5/2021 Muscles of the Pectoral Girdle and Upper Limbs | Anatomy and Physiology I Table 3. Muscles That Move the Forearm Movement Target Target motion direction Prime mover Origin Ins Forearm Flexion; supination Biceps brachii Coracoid process; tubercle above glenoid cavity Rad tub Forearm Flexion Brachialis Front of distal humerus Co pro uln Brachioradialis Lateral supracondylar ridge at distal end of humerus Bas sty pro rad Triceps brachii Infraglenoid tubercle of scapula; posterior shaft of humerus; posterior humeral shaft distal to radial groove Ole pro uln Anconeus Lateral epicondyle of humerus Lat asp ole pro uln Anterior muscles ( exion) Performs a bicep curl; also allows palm of hand to point toward body while exing Assists and stabilizes elbow during bicep-curl motion Forearm Flexion Posterior muscles (extension) Extends forearm, as during a punch Assists in extending forearm; also allows forearm to extend away from body Forearm Extension Forearm Extension; abduction Anterior muscles (pronation) … 11/22 4/5/2021 Muscles of the Pectoral Girdle and Upper Limbs | Anatomy and Physiology I Table 3. Muscles That Move the Forearm Movement Target Target motion direction Prime mover Origin Ins Lat rad Turns hand palmdown Forearm Pronation Pronator teres Medial epicondyle of humerus; coronoid process of ulna Assists in turning hand palmdown Forearm Pronation Pronator quadratus Distal portion of anterior ulnar shaft Dis sur ant rad Supinator Lateral epicondyle of humerus; proximal ulna Pro end rad Posterior muscles (supination) Tuns hand palm-up Forearm Supination Muscles That Move the Wrist, Hand, and Fingers Wrist, hand, and nger movements are facilitated by two groups of muscles. The forearm is the origin of the extrinsic muscles of the hand. The palm is the origin of the intrinsic muscles of the hand. Muscles of the Arm That Move the Wrists, Hands, and Fingers The muscles in the anterior compartment of the forearm (anterior exor compartment of the forearm) originate on the humerus and insert onto di erent parts of the hand. These make up the bulk of the forearm. From lateral to medial, the super cial anterior compartment of the forearm includes the exor carpi radialis, palmaris longus, exor carpi ulnaris, and exor digitorum super cialis. The exor digitorum super - cialis exes the hand as well as the digits at the knuckles, which allows for rapid nger movements, as in typing or playing a musical instrument (see Table 4). However, poor ergonomics can irritate the tendons of these muscles as they slide back and forth with the carpal tunnel of the … 12/22 4/5/2021 Muscles of the Pectoral Girdle and Upper Limbs | Anatomy and Physiology I anterior wrist and pinch the median nerve, which also travels through the tunnel, causing Carpal Tunnel Syndrome. The deep anterior compartment produces exion and bends ngers to make a st. These are the exor pollicis longus and the exor digitorum profundus. The muscles in the super cial posterior compartment of the forearm (super cial posterior extensor compartment of the forearm) orig- inate on the humerus. These are the extensor radialis longus, extensor carpi radialis brevis,extensor digitorum, extensor digiti minimi, and the extensor carpi ulnaris. The muscles of the deep posterior compartment of the forearm (deep posterior extensor compartment of the forearm) originate on the radius and ulna. These include the abductor pollicis longus, extensor pollicis brevis,extensor pollicis longus, and extensor indicis (see Table 4). … 13/22 4/5/2021 Muscles of the Pectoral Girdle and Upper Limbs | Anatomy and Physiology I Table 4. Muscles That Move the Wrist, Hands, and Forearm Movement Target Target motion direction Prime mover Origin Insertio Flexor carpi radialis Medial epicondyle of the humerus Base o second third metaca Palmaris longus Medial epicondyle of the humerus Palmar aponeu skin an fascia o palm Flexor carpi ulnaris Medial epicondyle of the humerus, the olecranon process, and the posterior surface of the ulna Pisiform hamate bones, base of metaca Flexor digitorum super cialis Medial epicondyle of the humerus, the coronoid process of the ulna, and the shaft of the radius Middle phalang of nge 5 Super cial anterior compartment of forearm Bends the wrist toward the body; it also tilts the hand to the side away from the body Assists in bending the hand up toward the shoulder Assists in bending the hand up toward the shoulder; it also tilts the hand to the side away from the body and stabilizes the wrist Bends the ngers to make a st Wrist; hand Wrist Wrist; hand Wrist; ngers 2–5 Flexion; abduction Flexion Flexion; abduction Flexion Deep anterior compartment of forearm … 14/22 4/5/2021 Muscles of the Pectoral Girdle and Upper Limbs | Anatomy and Physiology I Table 4. Muscles That Move the Wrist, Hands, and Forearm Movement Bends the tip of the thumb Bends the ngers to make a st; it also bends the wrist toward the body Target Thumb Wrist; ngers Target motion direction Prime mover Origin Insertio Flexion Flexor pollicis longus Anterior surface of the radius and the interosseous membrane Distal phalanx thumb Flexor digitorum profundus Coronoid process, the anteromedial surface of the ulna, and the interosseous membrane Distal phalang of nge 5 Flexion Super cial posterior compartment of forearm Straightens the wrist away from the body; it also tilts the hand to the side away from the body Assists the extensor radialis longus in extending and abducting the wrist; it also stabilizes the hand during nger exion Wrist Extension; abduction Extensor radialis longus Lateral supracondylar ridge of the humerus Base o second metaca Wrist Extension; abduction Extensor carpi radialis brevis Lateral epicondyle of the humerus Base o metaca … 15/22 4/5/2021 Muscles of the Pectoral Girdle and Upper Limbs | Anatomy and Physiology I Table 4. Muscles That Move the Wrist, Hands, and Forearm Movement Target Opens the ngers and moves them sideways away from the body Wrist; ngers Extends the little nger Little nger Straightens the wrist away from the body; it also tilts the hand to the side toward the body Wrist Target motion direction Prime mover Origin Insertio Extension; abduction Extensor digitorum Lateral epicondyle of the humerus Extenso expans distal phalang of nge Extension Extensor digiti minimi Lateral epicondyle of the humerus Extenso expans distal phalanx nger 5 Extension; abduction Extensor carpi ulnaris Lateral epicondyle of the humerus and the posterior of the ulna Base o metaca Abductor pollicis longus Posterior surface of the radius and ulna and in the interosseous membrane Base o metaca trapezi Extensor pollicis brevis Dorsal shaft of the radius and ulna and in the interosseous membrane Base o proxima phalanx thumb Deep posterior compartment of forearm Moves the thumb sideways toward the body; it also extends the thumb and moves the hand sideways toward the body Extends the thumb Wrist; thumb Thumb Thumb: abduction, extension; wrist: abduction Extension … 16/22 4/5/2021 Muscles of the Pectoral Girdle and Upper Limbs | Anatomy and Physiology I Table 4. Muscles That Move the Wrist, Hands, and Forearm Movement Target Extends the thumb Thumb Extends the index nger; it also straightens the wrist away from the body Wrist; index nger Target motion direction Prime mover Origin Insertio Extension Extensor pollicis longus Dorsal shaft of the radius and ulna and in the interosseous membrane Base o distal phalanx thumb Extensor indicis Posterior surface of the distal ulna and in the interosseous membrane Tendon extenso digitoru nger Extension The tendons of the forearm muscles attach to the wrist and extend into the hand. Fibrous bands called retinacula sheath the tendons at the wrist. The exor retinaculum extends over the palmar surface of the hand while the extensor retinaculum extends over the dorsal surface of the hand. Intrinsic Muscles of the Hand The intrinsic muscles of the hand both originate and insert within it (Figure 5). These muscles allow your ngers to also make precise movements for actions, such as typing or writing. These muscles are divided into three groups. The thenar muscles are on the radial aspect of the palm. The hypothenar muscles are on the medial aspect of the palm, and the intermediate muscles are midpalmar. … 17/22 4/5/2021 Muscles of the Pectoral Girdle and Upper Limbs | Anatomy and Physiology I Figure 5. Intrinsic Muscles of the Hand. The intrinsic muscles of the hand both originate and insert within the hand. These muscles provide the ne motor control of the ngers by exing, extending, abducting, and adducting the more distal nger and thumb segments. The thenar muscles include the abductor pollicis brevis, opponens pollicis, exor pollicis brevis, and the adductor pollicis. These muscles form the thenar eminence, the rounded contour of the base of the thumb, and all act on the thumb. The movements of the thumb play an integral role in most precise movements of the hand. The hypothenar muscles include the abductor digiti minimi, exor digiti minimi brevis, and the opponens digiti minimi. These muscles form the hypothenar eminence, the rounded contour of the little nger, and as such, they all act on the little nger. Finally, the intermediate muscles act on all the ngers and include the lumbrical, the palmar interossei, and the dorsal interossei. … 18/22 4/5/2021 Muscles of the Pectoral Girdle and Upper Limbs | Anatomy and Physiology I Table 5. Muscles That Move the Wrist, Hands, and Forearm Target motion direction Prime mover Orig Thumb Abduction Abductor pollicis brevis Flexo retin near carp Moves thumb across palm toward body Thumb Opposition Opponens pollicis Flexo retin trape Thenar muscles Flexes thumb Thumb Flexion Flexor pollicis brevis Felx retin trape Thenar muscles Moves thumb away from body Thumb Adduction Adductor pollicis Cap bone of meta 2–4; meta Hypothenar muscles Moves little nger toward body Little nger Abduction Abductor digiti minimi Pisif bone Hypothenar muscles Flexes little nger Little nger Flexion Flexor digiti minimi brevis Ham bone retin Hypothenar muscles Moves little nger across palm to touch thumb Little nger Opposition Opponens digiti minimi Ham bone retin Intermediate muscles Flexes each nger at metacarpophalangeal joints; extends each nger at interphalangeal joints Lumbricals Palm side tend exo digit prof Muscle Moveme...
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