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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
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
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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
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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
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
Serratus Anterior
Innervation:Long thoracic nerve
Action:Rotates scapula
Primitively a BODY WALL MUSCLE
Rhomdoidius Minor
Origin:Spines of C7 and T1
Insertion:Medial edge of scapula
Note: minor is superior (cranial), but SMALLER
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
ElevatorsTeres Minor
Origin: Lower edge of scapulaInsertion: Greater tubercleAction: Laterally rotates humerusInnervation: Axillary