Pectoral Region and Proximal Upper Limb - Vocabulary Flashcards

Overview of the Proximal Upper Limb

  • Focus: Proximal upper limb anatomy with emphasis on the pectoral region, bones, joints, muscles, vessels, and nerves.
  • Key bones to know: clavicle, scapula, humerus.
  • Orientation and landmarks are introduced via multiple views (anterior and superior/inferior perspectives, as in clavicle orientation).
  • Recurrent reference points: AC joint, glenohumeral joint, coracoclavicular ligaments, costoclavicular ligament, subclavian groove, triangular sternal end, flat acromial end, smooth superior shaft.
  • Major ligaments/joints mentioned in relation to the clavicle and shoulder girdle include: coracoclavicular ligament, acromioclavicular joint, glenohumeral joint, and costoclavicular ligament.

Bones of the Proximal Upper Limb

  • Clavicle
    • Key features to identify: acromial (lateral) end, sternal (medial) end, superior shaft, inferior surface with subclavian groove (for the subclavian vessels).
    • Inferior view considerations: subclavian groove, coracoclavicular ligament attachment, costoclavicular ligament near the medial aspect.
    • Role in shoulder girdle: transmits forces between upper limb and trunk; acts as a strut to hold the upper limb away from the thorax.
  • Scapula
    • Articulates with the clavicle at the acromioclavicular joint and with the humerus at the glenohumeral joint.
    • Major joints associated: glenohumeral joint; acromioclavicular joint (AC joint).
  • Humerus
    • Proximal articulation with the scapula at the glenohumeral joint.

Clavicle Orientation and Landmarks

  • Superior view: identify the acromial end (lateral) and the sternal end (medial).
  • Anterior vs. posterior surfaces: anterior surface vs. posterior surface markers.
  • Inferior view: subclavian groove (for subclavian vessels) and the costoclavicular ligament attachment.
  • Coracoclavicular ligament and AC joint are important stabilizers of the clavicle.
  • Additional related structures:
    • Clavicle
    • Acromioclavicular joint
    • Coracoclavicular ligament
    • Costoclavicular ligament
    • Glenohumeral joint (humerus–glenoid fossa interaction)
  • Coracoclavicular and AC joint integrity is essential for normal shoulder mechanics and for transmitting loads from the upper limb to the trunk.

Pectoral Region: Muscles, Arteries, Veins, and Innervation

Muscles and Functions

  • Pectoralis major
    • Origins:
    • Clavicular head from the medial half of the clavicle.
    • Sternocostal head from the sternum and costal cartilages 1–7 (and sometimes 8).
    • Insertion: Lateral lip of the intertubercular (bicipital) groove of the humerus.
    • Actions:
    • Adducts the arm.
    • Medially rotates the humerus.
    • Clavicular head contributes to flexion of the arm.
    • Innervation: Lateral pectoral nerve (from the lateral cord of the brachial plexus).
    • Blood supply: Pectoral branches of the Thoracoacromial trunk (primary supply to pectoralis major).
  • Pectoralis minor
    • Origins: Ribs 3–5.
    • Insertion: Coracoid process of the scapula.
    • Actions: Stabilizes the scapula by drawing it anteriorly and inferiorly against the thoracic wall.
    • Innervation: Medial pectoral nerve (C8–T1).
    • Blood supply: Perforating branches of thoracoacromial trunk and/or surrounding vessels; commonly accompanying medial pectoral innervation.
  • Deltoid
    • Origins: Lateral third of the clavicle, acromion, and spine of the scapula.
    • Insertion: Deltoid tuberosity of the humerus.
    • Actions:
    • Abducts the arm from about 15° to 90°.
    • Anterior fibers flex and medially rotate the arm.
    • Posterior fibers extend and laterally rotate the arm.
    • Innervation: Axillary nerve (C5–C6).
    • Blood supply: Posterior circumflex humeral artery; accessory supply from deltoid branches of the thoracoacromial trunk.
  • Serratus anterior
    • Origins: Ribs 1–8 or 9.
    • Insertion: Medial (vertebral) border of the scapula.
    • Actions:
    • Protracts the scapula (serratus pushing the scapula forward).
    • Holds the scapula against the thoracic wall.
    • Upwardly rotates the scapula to enable full arm abduction beyond ~90°.
    • Innervation: Long thoracic nerve (C5–C7).
    • Blood supply: Lateral thoracic artery; thoracodorsal artery (and contributions from intercostal arteries in some individuals).
  • Subclavius
    • Origins: First rib near its costal cartilage.
    • Insertion: Inferior surface of the clavicle (mid-clavicle region).
    • Actions: Stabilizes and depresses the clavicle; protects subclavian vessels during clavicular movement.
    • Innervation: Nerve to subclavius (C5–C6).
    • Blood supply: Branches accompanying subclavius nerve and surrounding vessels.

Arteries and Blood Supply (Axillary Region)

  • Axillary artery: primary arterial supply to the upper limb, with three parts and several branches.
    • Part 1: Superior thoracic artery.
    • Part 2: Thoracoacromial trunk and lateral thoracic artery.
    • Thoracoacromial trunk branches:
      • Pectoral branch
      • Deltoid branch
      • Clavicular branch
      • Acromial branch (less often emphasized in all texts, sometimes included within acromial supply)
    • Lateral thoracic artery supplies the lateral thorax and often the pectoral region.
    • Part 3: Subscapular artery, anterior humeral circumflex (AHCa), posterior humeral circumflex (PHCa).
    • Subscapular artery gives rise to:
      • Thoracodorsal artery
      • Circumflex subscapular artery (which surrounds the scapula)
  • Specific vessel contributions to the pectoral region muscles
    • Pectoralis major: primarily supplied by pectoral branches of the Thoracoacromial trunk.
    • Pectoralis minor: supplied by medial pectoral branches (and possibly perforating branches from nearby arteries).
    • Deltoid: supplied by deltoid branches (from the Thoracoacromial trunk) and the posterior circumflex humeral artery.
    • Serratus anterior: supplied by the lateral thoracic artery and thoracodorsal artery contributions.
    • Subclavius: supplied by branches of the subclavian/axillary region via nerve-to-artery connections.
  • Veins (draining the region)
    • Cephalic vein (lateral aspect of the arm and forearm) commonly drains into the axillary vein.
    • Axillary vein (receives tributaries from the brachial veins and the cephalic vein) as a major venous channel of the axillary region.

Nerves and Innervation (Brachial Plexus Related)

  • Brachial plexus overview (roots, trunks, divisions, cords, branches)
    • Roots: C5, C6, C7, C8, T1.
    • Trunks: Upper, Middle, Lower.
    • Divisions: Anterior and Posterior divisions from each trunk.
    • Cords: Lateral, Posterior, Medial.
    • Terminal nerves (illustrative list):
    • Musculocutaneous nerve
    • Axillary nerve
    • Median nerve
    • Ulnar nerve
    • Radial nerve
    • Major contributing nerves to the pectoral region include:
    • Lateral pectoral nerve (from lateral cord) – innervates pectoralis major.
    • Medial pectoral nerve (from medial cord) – innervates pectoralis minor and pectoralis major.
    • Thoraco-dorsal nerve (also called thoracodorsal nerve) – innervates latissimus dorsi; relation to posterior cord.
    • Long thoracic nerve (arises from roots C5–C7) – innervates serratus anterior.
    • Nerve to subclavius (from upper trunk or fusion near the subclavian region).
    • Cutaneous branches (skin innervation): anterior and lateral cutaneous branches of intercostal nerves (approx. T2–T6 vicinity) provide cutaneous innervation to surrounding chest wall; some interconnect with pectoral muscles via motor fibers in the brachial plexus.
  • Important conceptual note
    • The Long Thoracic Nerve (C5–C7) should not be confused with any named ‘Long Thoracic Artery’; blood supply to serratus anterior primarily involves the Lateral Thoracic Artery and Thoracodorsal artery contributions.
    • Some slides emphasize distinguishing nerves from arteries: e.g., the Long Thoracic Nerve is not an artery and does not provide blood supply. When practicing the axillary artery branches, memorize the arterial branches; when studying innervation, memorize the nerves.

Brachial Plexus Diagram Highlights (from slides)

  • Roots: C5, C6, C7, C8, T1
  • Major nerves near the pectoral region: Lateral pectoral nerve, Medial pectoral nerve, Thoraco-dorsal nerve, Long thoracic nerve, Nerve to subclavius, Axillary nerve, Musculocutaneous nerve, Median nerve, Ulnar nerve, Radial nerve, Medial cutaneous nerve of arm/forearm.
  • Cords and their associated branches (illustrative relationships):
    • Lateral cord: Lateral pectoral nerve; Musculocutaneous nerve; part of Median nerve.
    • Medial cord: Medial pectoral nerve; Median nerve; Medial cutaneous nerves of the forearm.
    • Posterior cord: Axillary nerve; Radial nerve; Thoracodorsal nerve; Upper/Lower subscapular nerves.

Practice and Application

  • Practice exercise (as per slides): Draw and label the branches of the axillary artery and indicate which artery supplies:
    • Pectoralis major: Pectoral branch of the Thoracoacromial trunk.
    • Pectoralis minor: Medial pectoral branches.
    • Deltoid: Deltoid branch of the Thoracoacromial trunk and/or perforating branches along with the posterior circumflex humeral artery.
    • Serratus anterior: Lateral thoracic artery and thoracodorsal artery contributions.
    • Subclavius: Subclavian region branches accompanying nerve to subclavius.
  • Direction of blood flow (conceptual reminder)
    • Arterial flow moves from heart to periphery; venous return moves from periphery toward the heart. In the upper limb, arterial pathways include the axillary artery and its branches; venous return includes the cephalic and axillary veins.
  • Skin vs. muscle innervation question (from slides)
    • Why don’t cutaneous nerves innervate muscles? Cutaneous nerves primarily supply the skin; motor innervation to muscles is via motor branches of the brachial plexus (e.g., musculocutaneous, axillary, suprascapular, dorsal scapular, long thoracic, etc.). Some fibers contributing to skin sensation accompany motor nerves near the same trunks, but cutaneous nerves themselves are for skin innervation.

Review Outline (from slides)

  • Muscles and Functions
    • Pectoralis major, Pectoralis minor, Deltoid, Serratus anterior, Subclavius.
  • Arteries and Blood Supply
    • Axillary artery and its branches: Superior thoracic; Thoracoacromial trunk (Pectoral, Deltoid, Clavicular branches); Lateral thoracic.
    • Pectoral region-specific arterial supply details as above.
  • Veins
    • Cephalic vein; Axillary vein.
  • Nerves and Innervation
    • Lateral pectoral; Medial pectoral; Long thoracic; Axillary; N. to subclavius; Anterior and lateral cutaneous branches of intercostal nerves.
  • Review Questions (typical prompts)
    • What are the functions of the muscles listed?
    • What blood vessels supply the muscles listed?
    • What nerves innervate the muscles listed?

Quick References to Visuals (from slides)

  • Pectoralis major image and labeling (Page 13, 20–21 references)
    • Shows clavicular and sternocostal heads and their relation to the pectoral region.
  • Arm and shoulder vascular/nerve maps
    • Axillary artery branches and relationship to pectoral region muscles.
    • Brachial plexus schematic with roots C5–T1 and major nerves.
  • Additional images (Wikimedia/OpenStax/Copyrights)
    • Used to illustrate the pectoral region, axillary artery branches, and brachial plexus arrangement.

Key Formulas and Notation (LaTeX)

  • Nerve roots: C5, C6, C7, C8, T_1
  • Muscle attachments and innervation summaries can be notated in shorthand, e.g.:
    • Pectoralis major innervation: ext{Nerve} = ext{Lateral pectoral nerve} o ext{C5–C7}
    • Serratus anterior innervation: ext{Nerve} = ext{Long thoracic nerve} o C5–C7
  • Branching patterns (axillary artery; simplified):
    • Part 1: ext{Superior thoracic artery}
    • Part 2: ext{Thoracoacromial trunk}, ext{Lateral thoracic artery}
    • Part 3: ext{Subscapular artery}, ext{Anterior humeral circumflex}, ext{Posterior humeral circumflex}
  • Action descriptors can use standard language; no numeric equations are required beyond the anatomical labeling above.

Note: Some slide text is garbled or abbreviated (e.g., open-source image credits and some labels). Where a term is ambiguous (e.g., “Long Thoracic A.”), the standard anatomical interpretation is used in these notes: the serratus anterior is supplied primarily by the Lateral Thoracic Artery and Thoracodorsal Artery branches, not by a separate “Long Thoracic Artery”.


If you want, I can tailor these notes further for a specific exam format (e.g., more compact flashcards, or a tabular comparison of the muscles with origins, insertions, actions, innervation, and blood supply).