THE MUSCULAR SYSTEM (ANATOMY)

Copyright © 2010 Pearson Education, Inc.

THE MUSCULAR SYSTEM(ANATOMY)

CHAPTER # 10(c)


Muscles Crossing the Shoulder Joint

• Nine muscles cross the shoulder joint to insert on and move the humerus



• Some originate off the scapula; others originate off the axial skeleton

• Three are prime movers of the arm

• Pectoralis major

• Latissimus dorsi

• Deltoid

• Actions include flexion, extension, adduction, abduction, and rotation of humerus



PLAYPLAY A&P Flix™: Deltoid

PLAYPLAY A&P Flix™: Latissimus dorsi

PLAYPLAY A&P Flix™: Pectoralis major



• Four muscles are rotator cuff muscles

• Supraspinatus

• Infraspinatus

• Teres minor

• Subscapularis

• Reinforce the capsule of the shoulder

• Act as synergists and fixators

• Two additional muscles are synergists: coracobrachialis and teres major



PLAYPLAY A&P Flix™: Movement from the rotator cuff muscles (a)

PLAYPLAY A&P Flix™: Muscles that cross the glenohumeral joint

PLAYPLAY A&P Flix™: Movement from the rotator cuff muscles (b)

PLAYPLAY A&P Flix™: Teres Major


Rotator Cuff Anatomy and Function

PLAYPLAY A&P Flix™: Supraspinatus

PLAYPLAY A&P Flix™: Subscapularis

PLAYPLAY A&P Flix™: Infraspinatus

PLAYPLAY A&P Flix™: Teres minor

PLAYPLAY A&P Flix™: Rotator cuff muscles

Copyright © 2010 Pearson Education, Inc. Figure 10.14a

Clavicle

Deltoid

Sternum

Pectoralis major

Lateral headLong headMedial head

CoracobrachialisTriceps brachii:

Biceps brachiiBrachialisBrachioradialis

(a) Anterior view



PLAYPLAY A&P Flix™: Axial muscles of the glenohumeral joint (a)

PLAYPLAY A&P Flix™: Scapular muscles of the glenohumeral joint (a)

Copyright © 2010 Pearson Education, Inc. Figure 10.14b

Supraspinatus*Spine of scapula

(b) Posterior view

Deltoid (cut)Greater tubercleof humerusInfraspinatus*

Teres minor*

Teres major

Triceps brachii:

Latissimus dorsi

HumerusOlecranon processof ulna

Lateral head Long head

Anconeus

* Rotator cuff muscles



PLAYPLAY A&P Flix™: Scapular muscles of the glenohumeral joint (b)

PLAYPLAY A&P Flix™: Axial muscles of the glenohumeral joint (b)


PLAYPLAY A&P Flix™: Movement at the glenohumeral joint (a)

PLAYPLAY A&P Flix™: Movement at the glenohumeral joint: An overview

PLAYPLAY A&P Flix™: Movement at the glenohumeral joint (b)

Movement at the Glenohumeral Joint


PLAYPLAY A&P Flix™: Muscles of the elbow joint (a)

PLAYPLAY A&P Flix™: The elbow joint and forearm: An overview

Muscles Crossing the Elbow Joint

• Anterior flexor muscles

• Brachialis and biceps brachii—chief forearm flexors

• Brachioradialis—synergist and stabilizer


Clavicle

Deltoid

Sternum

Pectoralis major

Lateral headLong headMedial head

CoracobrachialisTriceps brachii:

Biceps brachiiBrachialisBrachioradialis

(a) Anterior view



PLAYPLAY A&P Flix™: Biceps brachii

PLAYPLAY A&P Flix™: Muscles of the elbow joint (b)

PLAYPLAY A&P Flix™: Brachialis

PLAYPLAY A&P Flix™: Brachioradialis



• Posterior extensor muscles

• Triceps brachii—prime mover of forearm extension

• Anconeus—weak synergist


Supraspinatus*Spine of scapula

(b) Posterior view

Deltoid (cut)Greater tubercleof humerusInfraspinatus*

Teres minor*

Teres major

Triceps brachii:

Latissimus dorsi

HumerusOlecranon processof ulna

Lateral head Long head

Anconeus

* Rotator cuff muscles



PLAYPLAY A&P Flix™: Triceps brachii

PLAYPLAY A&P Flix™: Muscles of the elbow joint (c)


PLAYPLAY A&P Flix™: Movement at the elbow joint

Tricepsbrachii

Lateralhead

Humerus

LongheadMedialhead

(a)

Brachialis

Short headLong head

(a) Muscles of the arm

Extensors

Flexors

Others

Posteriorcompartment

of arm (extendselbow); innervation:

radial nerve

Biceps brachii

Anterior compartment of arm (flexes elbow); innervation:musculocutaneous nerve


Muscles of the Forearm

• Actions: movements of the wrist, hand, and fingers

• Most anterior muscles are flexors and insert via the flexor retinaculum

• Most posterior muscles are extensors and insert via the extensor retinaculum

PLAYPLAY A&P Flix™: Muscles that act on the wrist and fingers: An overview


PLAYPLAY A&P Flix™: Muscles of the forearm (a)


• Some forearm muscles act to produce pronation and supination of the forearm



• Pronators: pronator teres and pronator quadratus

• Supinator: a synergist with the biceps brachii

PLAYPLAY A&P Flix™: Pronator teres

PLAYPLAY A&P Flix™: Muscles of the forearm (c)

PLAYPLAY A&P Flix™: Muscles of the forearm (b)

PLAYPLAY A&P Flix™: Supinator


Muscles of the Forearm: Anterior Compartment

• Flexors

• Flexor carpi radialis

• Palmaris longus

• Flexor carpi ulnaris

• Flexor digitorum muscles (superficialis and profundus)

• Flexor pollicis longus

PLAYPLAY A&P Flix™: Carpal tunnel


Biceps brachii

Tendon of biceps brachii

Pronator teres

Brachioradialis

Extensor carpi radialis longus

Flexor pollicis longus

Pronator quadratus

Flexor retinaculum

Medial head oftriceps brachii

Medial epicondyleof humerus

Flexor carpi radialis

Palmar aponeurosis

Superficial transverseligament of palm

Palmaris longus

Flexor carpi ulnaris

Flexor digitorumsuperficialis

(a)



PLAYPLAY A&P Flix™: Flexor carpi ulnaris

PLAYPLAY A&P Flix™: Flexor carpi radialis

PLAYPLAY A&P Flix™: Anterior Muscles of the wrist and fingers (b)

PLAYPLAY A&P Flix™: Flexor digitorum superificalis

Copyright © 2010 Pearson Education, Inc. Figure 10.15c

Supinator

Tendon of flexorcarpi ulnaris (cut)

Tendon of flexordigitorum profundus

Flexor pollicis longus

Thenar muscles of thumb

Tendon of flexorpollicis longus

Lumbricals

Tendon of flexor digitorumsuperficialis (cut)

Pronator quadratus

Flexor digitorumprofundus

(c)



PLAYPLAY A&P Flix™: Anterior Muscles of the wrist and fingers (a)


Muscles of the Forearm: Posterior Compartment

• Extensors

• Extensor carpi radialis longus and brevis

• Extensor digitorum

• Extensor carpi ulnaris

• Extensor pollicis brevis and longus

• Extensor indicis

• Abductor pollicis longus


Insertion oftriceps brachii

Anconeus

Flexor carpiulnaris

Extensor carpiulnaris

Extensor digitiminimi

Extensor indicis

Tendons of extensor carpiradialis brevis and longus

Extensorexpansion

(a)

Extensor pollicislongusExtensor pollicisbrevisAbductorpollicis longusExtensor digitorum

Extensor carpiradialis brevis

Extensor carpiradialis longus

Brachioradialis

Tendons ofextensordigitorum



PLAYPLAY A&P Flix™: Extensor carpi radialis longus

PLAYPLAY A&P Flix™: Posterior Muscles of the wrist and fingers (b)

PLAYPLAY A&P Flix™: Extensor carpi radialis brevis

PLAYPLAY A&P Flix™: Extensor digitorum

PLAYPLAY A&P Flix™: Extensor carpi ulnaris(c)


Olecranon process of ulna

Interossei

Anconeus

Supinator

Abductor pollicis longus

Extensor pollicis longus

Extensor pollicis brevis

Extensor indicis

(b)



PLAYPLAY A&P Flix™: Posterior Muscles of the wrist and fingers (a)


Movements of the Wrist and Fingers

• Flexion and extension

• Abduction and adduction

PLAYPLAY A&P Flix™: Movements of the wrist and fingers (b)

PLAYPLAY A&P Flix™: Movements of the wrist and fingers (a)


Extensors

Flexors

Others

(b)

Flexors

Extensors

Ulna

Posterior compartment of forearm(extends wrist and fingers);innervation: radial nerve

Others

Radius

Pronatorteres Brachioradialis(elbow flexor)

Abductorpollicis longus

(b) Muscles of the forearm

Anterior compartment of forearm (flexes wrist and fingers); innervation: median or ulnar nerve


Intrinsic Muscles of the Hand

• Small weak muscles

• Lie entirely within the palm of the hand

• Control precise movements of metacarpals and fingers (e.g., threading a needle)

• Abductors and adductors of the fingers

• Produce opposition—move the thumb toward the little finger


Finger and Thumb Movements

• Flexion

• Thumb—bends medially along the palm

• Fingers—bend anteriorly

• Extension

• Thumb—points laterally

• Fingers—move posteriorly



• Three groups

• Thenar eminence (ball of the thumb)

• Hypothenar eminence (ball of the little finger)

• Each of the above groups has a flexor, an abductor, and an opponens muscle

• Midpalmar muscles: lumbricals and palmar and dorsal interossei extend the fingers

• Interossei muscles also abduct and adduct the fingers


Flexor digitorumprofundus

Tendons of:

Flexor digitorumsuperficialis

Thirdlumbrical

Fourthlumbrical

Opponensdigiti minimi

Flexor digitiminimi brevis

Abductordigiti minimi

Pisiform bone

Flexor carpiulnaris tendon

Flexor digitorumsuperficialistendons Flexor pollicis longus

Flexor carpi radialisPalmaris longus

Flexor retinaculum

Abductor pollicislongus

Opponens pollicis

Abductor pollicisbrevis

Flexor pollicisbrevis

Adductor pollicis

Dorsal interossei

First lumbrical

Second lumbrical

Fibrous sheath

(a) First superficial layer

Tendons of:


Flexor digitorumprofundus tendon

Flexor digitorumsuperficialis tendon

Palmar interossei

Opponens digitiminimi

Flexor digiti minimibrevis (cut)

Abductor digiti minimi(cut)

Flexor pollicis longustendon

Opponens pollicis

Abductor pollicisbrevis

Flexor pollicisbrevis

Adductor pollicis

Dorsal interossei

(b) Second layer



PLAYPLAY Animation: Rotatable hand

THE MUSCULAR SYSTEM (ANATOMY)

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