Classification of muscles of the

trunk

Figure 4.1

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Section 2 The Muscles of Trunk . The muscles of back trapezius, latissimus, levattor scapulae, rhomboid muscles erector spinae (sacrospinelis) thoracolumbar fascia. The muscles of thorax 1) The extrinsic muscles pectoralis major, pectoralis minor, serratus anterior 2) The intrinsic muscles intercostales extrerni, intercostales interni . The diaphragm . The muscles of abdomen

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Muscles of Thorax

Muscle Origin Insertion Action Innervation

Pectoralis major

Sternum, Ribs 2-6

Inter-tubercular groove of humerus

Adduct, Flex, Med Rotate Arm

M & L pectorals

Pectoralis minor

Ribs 3-5 Coracoid process of scapula

Depress, Rotate scapula

M & L pectorals

Serratus anterior (ventralis)

Ribs 1-9 Scapula Protract, Rotate scapula

Long Thoracic

Page 118, 646

Muscle Origin Insertion Action Innervation

Trapezius Ligamentum nuchae, C7-T12

Clavicle, Spine & acromion of scapula

Elevate, Adduct, Rotate, Depress

Accessory

Levator Scapulae

C1-C4 Medial border of scapula

Elevate scapula

D. Scapular

Rhomboids

C7-T5 Medial border of scapula

Adduct, Elevate, Rotate

D. Scapular

Muscles of Thorax Page 49

Muscles of Thorax

Muscle Origin Insertion Action Innervation

Deltoids Clavicle, Spin & acromion of scapula

Deltoid tuberosity of humerus

Flex, Abduct, Extend, Lat & med. rotate arm

Axillary

Latissimus dorsi

Iliac crest,

Sacrum, T7-12, Lumbar fascia

Inter-tubercular groove of humerus

Extend, Adduct, Med. rotate arm

Thoraco-dorsal

Anterior Surface of Thorax

• Palpate the following– Sternum (3 parts)– Jugular notch– Sternal Angle (= 2nd rib)– Clavicle– Costal margin – Xiphosternal joint

• Midclavicular Line• Midaxillary Line Page 201

Posterior Surface of Thorax

• Palpate the following– Spinous Process of C7– Scapula (ribs 2-7)

• Scapular spine• Acromion Process• Inferior Angle of Spine• Inferior Border

Page 90

Locating Internal Structures

• Pleural Cavities– Inferior margin = adjacent to

T12 in Posterior Midline– To Rib 10 at Midaxillary line– To Rib 8 at Midclavicular line– To Xiphosternal joint medially– Lungs posterior border is 2

ribs superior to pleural cavity (rib 8)

• Heart– Deep to xiphisternal angle Page 206

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Pectoralis Major

Pectoralis Minor

Trapezius

In more primitive species used for opening and closing gills - aBRANCHIAL muscle.

In humans, used to move scapula and keep head up

Trapezius

Origin:Occipital bone,Spines of C7 and T1-12

Insertion:AcromionSpine of scapulaLateral 1/3 of clavicle

Trapezius

Innervation:Accessory Nerve (Cranial Nerve XI)

Action:Extension of the headElevation and depression of scapula

Trapezius

Serratus Anterior

Origin:First 9 ribs

Insertion:Medial edge of scapula’s deep surface

Serratus Anterior

Innervation:Long thoracic nerve

Action:Rotates scapula

Primitively a BODY WALL MUSCLE

SerratusAnterior

Levator Scapulae

Origin:Transverse processes of C1-4

Insertion:Medial edge of scapula

Levator Scapulae

Innervation:Ventral Rami of C3 and C4

Action:Retracts scapula Depresses glenoid

Rhomdoidius Major

Origin:Spines of T2-T5

Insertion:Medial edge of scapula

Rhomdoidius Major

Innervation:Dorsal Scapula

Action:Retracts scapula Depresses glenoid

Rhomdoidius Minor

Origin:Spines of C7 and T1

Insertion:Medial edge of scapula

Note: minor is superior (cranial), but SMALLER

Rhomdoidius Minor

Innervation:Dorsal Scapula

Action:Retracts scapula Depresses glenoid

Levator Scapulae

Rhomboid Minor

Rhomboid Major

Levator ScapulaeRhom-boids

Pecoralis Minor

Depression

Trapezius

Trapezius

SerratusAnterior

Elevation

Latissimus Dorsi

Origin:Spines of T7-T12Thoracolumbar fascia

Insertion:Humerus: Inertubecular grooveAnd lesser tubecular crest

Innervation: Thoracodorsal Nerve

Latissiumus: Extends, adducts and medially rotates humerus

Pectoralis: is large, fan-shaped muscle opposing it ventrally

Pectoralis Major:

Clavicular Head:Origin: inferior margin of clavicleInsertion: Delto-pectoral crest of HUMERUS

Sternal Head:Origin: Ventro-lateral margin of sternumInsertion: Delto-pectoral crest of HUMERUS

Pectoralis Major:

Clavicular Head:

Origin: inferior margin of clavicle

Insertion: Greater tubercular crest of HUMERUS

Innervation: Medial and lateral pectoral nerves

Pectoralis Major:

Sternal Head:DEPRESSOR, ADDUCTOR of humerus

Origin: Ventro-lateral margin of sternum; costal cartilages 1-6

Insertion: Greater tubercular crest of HUMERUS

Innervation: Medial and lateral pectoral nerves

Pectoralis MINOR:Deep to Pec. Major

Origin:Ribs 3-6.

Insertion: Coracoid Process of Scapula

Innervation:

Function: Stabilization of scapula

Positionally important for understanding location of other structures.

Elevators Teres Major

Origin: Lower edge of scapulaInsertion: Lesser tubercular crestAction: Extends, Adducts & Medially rotates humerusInnervation: Lower scapular

ElevatorsSubscapularis

Origin: Deep surface of scapulaInsertion: Lesser tubercleAction: Medially rotates humerusInnervation: Upper and lower scapular

Internal View:

Subscapularis

ElevatorsTeres Minor

Origin: Lower edge of scapulaInsertion: Greater tubercleAction: Laterally rotates humerusInnervation: Axillary

Teres Minor