Anatomy of the Pectoral Region
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Questions and Answers

Which of the following structures is NOT pierced by the clavipectoral fascia?

  • Cephalic vein
  • Lateral pectoral nerve
  • Acromiothoracic vessel
  • Superior thoracic artery (correct)

    • What is the primary function of the costocoracoid membrane?

  • To support the axillary fascia during abduction of the arm
  • To provide attachment for the deltoid muscle
  • To allow for the passage of the lateral pectoral nerve to the pectoralis major muscle (correct)
  • To separate the pectoralis major and pectoralis minor muscles

    • Which of these structures is NOT directly involved in creating the osseofibrous compartments?

  • Infraspinous
  • Supraspinous
  • Serratus anterior
  • Clavipectoral fascia (correct)

    • Which of the following is NOT a layer of the pectoral region?

    <p>Periosteum (C)</p> Signup and view all the answers

    The clavicular head of the pectoralis major is responsible for what action, when acting alone?

    <p>Flexion of the humerus (B)</p> Signup and view all the answers

    What is the relationship between the pectoral fascia and the axillary fascia?

    <p>The pectoral fascia is continuous with the axillary fascia. (D)</p> Signup and view all the answers

    What is the main action of the Subclavius muscle?

    <p>Anchors and depresses the clavicle (A)</p> Signup and view all the answers

    Which of the following muscles is enclosed by the clavipectoral fascia?

    <p>Subclavius (A), Pectoralis minor (E)</p> Signup and view all the answers

    Which nerve supplies the Pectoralis Minor muscle?

    <p>Medial pectoral nerve (A)</p> Signup and view all the answers

    What is the attachment point of the Pectoralis Minor muscle?

    <p>Medial border and superior surface of the coracoid process of the scapula (C)</p> Signup and view all the answers

    Which of the following structures contributes to the formation of the axillary fossa during arm abduction?

    <p>The suspensory ligament of the axilla (E)</p> Signup and view all the answers

    Which of the following muscles is responsible for protracting the scapula and rotating it?

    <p>Serratus anterior (C)</p> Signup and view all the answers

    What is the primary function of the deltoid fascia?

    <p>To enclose the deltoid muscle and connect to other fasciae (D)</p> Signup and view all the answers

    From what structures does the Sternocostal head of the Pectoralis Major muscle originate?

    <p>Anterior surface of the sternum, superior six costal cartilages, and aponeurosis of the external oblique muscle (B)</p> Signup and view all the answers

    How does the deep fascia of the scapula contribute to the overall structure of the pectoral region?

    <p>It encloses the muscles that cover the anterior and posterior surfaces of the scapula (A), It separates the muscles of the pectoral region from those of the back. (E)</p> Signup and view all the answers

    The clavipectoral (deltopectoral) triangle is a triangular space bordered by what structures?

    <p>Clavicle, Pectoralis Major, and Deltoid (D)</p> Signup and view all the answers

    Flashcards

    Pectoral Region

    The area connecting the upper limb to the trunk.

    Layers of Pectoral Region

    Includes skin, superficial fascia, deep fascia, muscles, nerves, and vessels.

    Superficial Fascia

    Subcutaneous tissue beneath the skin, containing fat and structures like nerves and vessels.

    Deep Fascia

    A layer that attaches to bone if no structures intervene, encompassing muscles and nerves.

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    Pectoral Fascia

    Invests the pectoralis major and connects to the axillary fascia.

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    Clavipectoral Fascia

    Encloses the subclavius and pectoralis minor, connecting from the clavicle to the axillary fascia.

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    Lateral Pectoral Nerve

    Primarily supplies the pectoralis major and pierces the clavipectoral fascia.

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    Deltoid Fascia

    Envelops the deltoid muscle and is continuous with the pectoral fascia.

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    Pectoral Muscles

    Muscles located in the pectoral region including pectoralis major, minor, subclavius, and serratus anterior.

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    Pectoralis Major

    A large chest muscle that adducts and medially rotates the humerus; it has clavicular and sternocostal heads.

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    Pectoralis Minor

    A smaller muscle that stabilizes the scapula by drawing it inferiorly and anteriorly against the thoracic wall.

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    Subclavius

    A muscle that anchors and depresses the clavicle; it originates at the junction of the 1st rib and costal cartilage.

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    Serratus Anterior

    A muscle that protracts the scapula and holds it against the thoracic wall; innervated by the long thoracic nerve.

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    Pectoralis Major Innervation

    Lateral and medial pectoral nerves supply the pectoralis major; clavicular head (C5, C6) and sternocostal head (C7, C8, T1).

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    Clavipectoral Triangle

    A slightly depressed area below the lateral part of the clavicle, bounded by the clavicle, deltoid, and pectoralis major.

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    Testing Pectoralis Major

    Testing involves keeping the arm abducted and flexing against resistance for the clavicular head and adducting for the sternocostal head.

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    Study Notes

    Pectoral Region Anatomy

    • The pectoral region connects the upper limb to the trunk.

    • Layers of the pectoral region include:

      • Skin
      • Superficial fascia (contains cutaneous nerves and vessels)
      • Deep fascia (includes pectoral fascia and clavipectoral fascia)
      • Muscles
      • Nerves
      • Vessels

    • Deep to the skin is subcutaneous tissue (superficial fascia), containing fat and the mammary gland.

    • Cutaneous nerves include the mammary gland, supraclavicular nerve, and cutaneous branches of intercostal nerves.

    • Cutaneous vessels are also present.

    • If no muscle or tendon intervenes, deep fascia attaches to bone.

    • Pectoral fascia invests the pectoralis major and extends to the fascia of the anterior abdominal wall.

    • Pectoral fascia changes to axillary fascia along the lateral border of the pectoralis major, becoming the floor of the axilla.

    • The clavipectoral fascia is deeper to the pectoral fascia and pectoralis major.

    • The clavipectoral fascia originates from the clavicle and encloses the subclavius and pectoralis minor.

    • It continues to the axillary fascia inferiorly.

    • The costocoracoid membrane is a part of the clavipectoral fascia located between the pectoralis minor and subclavius.

    • The lateral pectoral nerve pierces the costocoracoid membrane, mainly supplying the pectoralis major.

    • The suspensory ligament of the axilla is an inferior part of the clavipectoral fascia, supporting the axillary fascia.

    • It pulls the axillary fascia and surrounding skin upward during arm abduction, forming the axillary fossa.

    • Clavipectoral fascia is pierced by:

      • Lateral pectoral nerve
      • Acromio-thoracic vessel
      • Cephalic vein
      • Lymphatics from the breast (draining into apical lymph nodes)

    • The scapulohumeral muscles are enveloped by deep fascia (deltoid fascia).

    • Deltoid fascia invests the deltoid and runs continuously with the pectoral fascia (anteriorly) and infraspinous fascia (posteriorly).

    • Deep fascia covers the scapula's anterior and posterior surfaces, attached to the scapula's margins.

    • This arrangement forms compartments: subscapular, supraspinous, and infraspinous.

    Pectoral Muscles

    • Pectoral muscles include:
      • Pectoralis major
      • Pectoralis minor
      • Subclavius
      • Serratus anterior

    Pectoralis Major

    • Origin: Clavicular head (medial half of clavicle); sternocostal head (anterior surface of sternum, costal cartilages, external oblique aponeurosis).
    • Attachment: Lateral lip of intertubercular sulcus (humerus).
    • Nerve supply: Lateral and medial pectoral nerves (clavicular head—C5, C6; sternocostal head—C7, C8, T1).
    • Action: Adducts and medially rotates the humerus, draws scapula anteriorly and inferiorly. Clavicular head flexes the humerus; sternocostal head extends it from the flexed position.

    Pectoralis Minor

    • Origin: 3rd to 5th ribs near their costal cartilages.
    • Attachment: Medial border and superior surface of coracoid process of scapula.
    • Nerve supply: Medial pectoral nerve (C8, T1).
    • Action: Stabilizes scapula by drawing it inferiorly and anteriorly against the thoracic wall.

    Subclavius

    • Origin: Junction of 1st rib and its costal cartilage
    • Attachment: Inferior surface of middle third of clavicle.
    • Nerve supply: Subclavian nerve (C5, C6).
    • Action: Anchors and depresses clavicle.

    Serratus Anterior

    • Origin: External surfaces of lateral parts of 1st to 8th ribs.
    • Attachment: Anterior surface of medial border of scapula.
    • Nerve supply: Long thoracic nerve (C5, C6, C7).
    • Action: Protracts scapula, holds it against thoracic wall, rotates scapula.

    Surface Anatomy

    • Large vessels and nerves to the upper limb pass posteriorly to the clavicle's convexity.
    • The slightly depressed area inferior to the lateral clavicle is the clavipectoral (deltopectoral) triangle.
    • It is bordered by the clavicle superiorly, the deltoid laterally, and the clavicular head of the pectoralis major medially.
    • During abduction and adduction movements against resistance, the two heads of the pectoralis major become visible and palpable.

    Testing of Pectoralis Major

    • Clavicular head: Abduct and then ask the individual to flex the arm against resistance.
    • Sternocostal head: Ask the individual to adduct the arm against resistance.

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