Pectoral region

Lecture 2

Muscle Action

Each muscle has:

Origin Beginning.

Insertion End.

Body (belly).

Law:

When a muscle

performs its action,

its insertion, moves

towards its origin.

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Pectoral Region

Spring 2016

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Pectoral Region

Breast region.

Contents:

1. Skin. 2. Superficial fascia. 3. Breast. 4. Deep fascia. 5. 3 Muscles:

a. Pectoralis major. b. Pectoralis minor. c. Subclavius.

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Pectoralis major

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Origin: Clavicle (M ½) , Sternum and upper 6 ribs. Insertion: humerus, lateral lip of intertubercular groove.

Nerve Supply: Medial & lateral pectoral nerves.

Action: Adducts and medially rotate the arm.

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Pectoralis Minor

O: 3rd, 4th, 5th ribs.

Ins: Coracoid process.

NS: Medial pectoral N.

Action: Depress scapula downward and forward.

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Subclavius

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Origin: 1st rib. Ins: Clavicle inferior surface.

NS: N. to Subclavius.

Action: Protects the underlying structures.

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Muscles connecting UL to vertebral col.

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Deltoid

O: Clavicle, acromion and

spine of scapula. Ins:

Deltoid tuberosity. Action:

Its fibers runs in 3

directions

• Ant. flex shoulder.

• Post. extend should. Dr. Maher Hadidi

• Middle Abduct arm 15-900.

NS: Axillary N.

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Trapezius

O: Skull, spines of C1-T12

v. Ins: Its fibers runs in 3 directions

• Down Clavicle. • Horizontal Acromion. • Up Spine of scapula.

Action: ▪Upper F. Elevate arm.

▪Middle F. adduct medial Dr. Maher Hadidi

▪ Lower F. pull downward

▪ Assist the serratus anterior muscle in abducting the arm 1800 above the head.

NS: Spinal accessory (IX) N.

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Latissmus dorsi

O: T7-T12, L1- L5, Sacrum & Iliac crest.

Ins: Floor of biceptal

groove

Action: extends, adducts

and medially rotate

humerus like in canoeing.

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NS: Thoracodorsal N.

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Scapular

muscles

Lecture 3

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Muscles connecting UL to scapula

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Supraspinatus

O: Supraspinous fossa.

Ins: Greater tubercle of

humerus.

Action: Abducts arm S

i

0-150. T

NS: Suprascapular N.

Infraspinatus

O: Infraspinous fossa.

Ins: Greater tubercle.

Action: Lateral rotation

of arm. Dr. Maher Hadidi

NS: Suprascapular N.

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Teres Minor

(L. Rounded)

O: Lat. border of Scapula.

Ins: Greater tubercle.

Action: Lateral rotation of arm. Dr. Maher Hadidi

NS: Axillary n.

Teres Major

O: Lat. border of Scapula.

Ins: Medial lip of i.t groove

Action: Adduction & Medial

rotation and of arm. NS: Lower subscapular n.

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Subscapularis

Origin: Subscapular

fossa.

Ins: Lesser tubercle.

Action: Medial rotation

of the arm.

NS: Upper and lower

subscapular Ns.

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Serratus anterior

Origin: upper 8 ribs.

Ins: Medial border of

scapula.

Act: Protraction of

scapula (pulls scapula forward over thoracic wall).

It assists trapezius to elevate arm 1800 above shoulder.

NS: Long thoracic N.

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Rotator cuff muscles of shoulder

➢ Form of 4 muscles:

Supraspinatus

Infraspinatus Teres minor i

S

Subscapularis T

➢Their tendons flatten at

their insertion and blend Dr. Maher Hadidi

with the capsule of the

shoulder joint. They act as

a handcuff that strengthen shoulder joint (superior,

posterior & anterior).

➢ But NOT inferior?

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Spaces between scapular muscles

Quadrangular space Borders:

• Sup. T. minor • Inf. T. major • Med. Triceps, long h. • Lat. humerus

Contents:• Axillary N. • Post. circ. hum. A,V.

Triangular space Dr. Maher Hadidi

Borders:

• Sup, T. minor • Inf, T. major

• Lat. Triceps, long head

Contents:• Circumflex scapular A & V.

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