Gross Anatomy: Pectoral & Axilla I Notes PDF

Gross Anatomy: Pectoral & Axilla I Page 1 of 17 Dr. Mark Ireland SESSION LEARNING OBJECTIVES By the end of this session, students should be able to accurately: 1. Describe the basic movements of the upper limb. 2. Identify and describe the ana...

Gross Anatomy: Pectoral & Axilla I Page 1 of 17 Dr. Mark Ireland SESSION LEARNING OBJECTIVES By the end of this session, students should be able to accurately: 1. Describe the basic movements of the upper limb. 2. Identify and describe the anatomical features of the bones of the pectoral (shoulder) girdle and proximal arm. 3. Describe the muscles that act on the pectoral girdle and proximal arm including attachments, innervations, and actions, & apply knowledge to evaluate clinical problems. 4. List the structural boundaries of the axilla. SESSION OUTLINE I. General Description of the Limbs and Their Movements II. Bones of the Pectoral Girdle 1. Clavicle 2. Scapula 3. Proximal Humerus III. Muscles Moving the Upper Limb 1. Superficial Back Muscles Connecting Vertebral Column to Arm 2. Scapular Muscles Connecting to Arm 3. Pectoral Muscles Connecting to Arm IV. Axilla 1. Definition 2. Boundaries a. Inlet or Apex b. Anterior Wall c. Posterior Wall d. Lateral Wall e. Medial Wall f. Floor Supplemental Reading Gray’s Anatomy for Students, 4th Ed (2020) Drake, Vogl, Mitchell (Elsevier) Chapter 7. Atlas of Human Anatomy, 7th Ed (2019) Netter (Elsevier) Gross Anatomy: Pectoral & Axilla I Page 2 of 17 Dr. Mark Ireland I. General Description of the Limbs (Fig 1 Gray’s 1.1) Regions of the limbs. Your upper and lower limbs are sometimes called upper and lower extremities or upper and lower members. The upper limb is divided into the arm (or brachium) located between the shoulder and elbow joints; the forearm (or antebrachium) located between the elbow and wrist joints; and the hand. The function of the upper limb is to position the hand in order to manipulate the environment. The lower limb is divided into the thigh located between the hip and knee joints; the leg located between the knee and ankle joints; and the foot. The function of the lower limb is to move the body as a unit in order to interact with the environment. Through muscle actions, these portions of the limbs are moved. It is not proper anatomy-speak to say a joint is moved (as in “I flexed my elbow joint” but rather “I flexed my Fig 11 Fig forearm” or “forearm flexion occurs at 2 the elbow joint”). General Movements of the Limbs. Body part movements are described as listed below. Additional, specialized terms and movements will be presented when necessary. Flexion: decreasing the angle between body parts, in general Extension: increasing the angle between body parts, in general Abduction: movement away from the median plane Adduction: movement toward the median plane Rotation: movement around a long axis spinning - Circumduction: circular movement combining flexion, extension, abduction and adduction ↳ moving body part in a circular motion through Gross Anatomy: Pectoral & Axilla I Page 3 of 17 Dr. Mark Ireland II. BONES OF THE PECTORAL GIRDLE 1. Clavicle (Fig 2 Gray’s 7.20) - S-shaped bone which is convex anteriorly in its medial two thirds and concave posteriorly in lateral one third. Its medial end is expanded to form an articulation with the sternum while its lateral end is flattened and presents an articular surface for the acromion of the scapula. Roughened areas are located on the inferior surface for ligament and muscle attachments. Fig 2  Gross Anatomy: Pectoral & Axilla I Page 4 of 17 Dr. Mark Ireland 2. Scapula (Fig 3 Gray’s 7.21) – Roughly triangular shaped bone with three borders, three fossae, two prominent protuberances and the glenoid cavity (considered as a fourth fossa) for articulation with the humerus. a accompan Fig 3 espirated ma considered a 4th headoumenes fossa subscapularis muscle Gross Anatomy: Pectoral & Axilla I Page 5 of 17 Dr. Mark Ireland 3. Proximal Humerus (Fig 4 Gray’s 7.22) - Long shaft with expanded ends for the shoulder and elbow joints. The proximal end presents a head for articulation with the glenoid cavity and a greater and lesser tubercle separated by an intertubercular groove or sulcus. Fig 4 Deltoid & musce attaches Gross Anatomy: Pectoral & Axilla I Page 6 of 17 Dr. Mark Ireland III. MUSCLES MOVING THE UPPER LIMB 1. Muscles Connecting Upper Limb to Vertebral Column (Fig 5 Gray’s 7.12)- these are classified as Superficial Muscles of the Back in Grant’s Dissector. Fig 5 & Free Muscle Origin Insertion Innervation Action trapezius sup. nuchal line, ext. lateral 1/3 clavicle, CN XI rotates, elevates, occipital acromion, spine of retracts and protuberance, scapula depresses scapula ligamentum nuchae, spinous processes of CV VII to TV XII latissimus dorsi spinous processes of intertubercular thoracodorsal n. extends, adducts TV VI to LV V and groove (also called and medially rotates sacrum, iliac crest intertubercular humerus and ribs X to XII sulcus) levator scapulae transverse superior angle of dorsal scapular n. elevates and rotates processes of CV I-IV scapula scapula rhomboid major and spinous processes of medial border of dorsal scapular n. retracts,elevates and minor CV VII to TV V scapula rotates scapula Gross Anatomy: Pectoral & Axilla I Page 7 of 17 Dr. Mark Ireland 2. Scapular Muscles (Fig 6 Gray’s 7.35) Scapular Muscles - Connecting Scapula to Arm (Lateral View) Fig 6 Muscle Origin Insertion Innervation Action deltoid spine of scapula, deltoid tuberosity axillary n. abduct, flex and acromion, lateral extend arm, 1/3 of clavicle medial and lateral rotation Gross Anatomy: Pectoral & Axilla I Page 8 of 17 Dr. Mark Ireland 2. Scapular Muscles (Fig 7 Gray’s 7.37) Connecting Scapula to Arm (Posterior View) 2 Fig 7 Muscle Origin Insertion Innervation Action supraspinatus supraspinous fossa superior facet of suprascapular n. arm abduction greater tubercle infraspinatus infraspinous fossa middle facet of suprascapular n. lateral rotation of greater tubercle arm teres major lateral scapular medial lip of lower subscapular n. medial rotation and border superior to intertubercular adduction of arm, inferior angle sulcus (also called extends a flexed arm crest of the lesser tubercle) teres minor lateral scapular inferior facet of axillary n. lateral rotation of border superior to greater tubercle arm teres major long head triceps infraglenoid tubercle olecranon process radial n. extends forearm of scapula via common tendon Gross Anatomy: Pectoral & Axilla I Page 9 of 17 Dr. Mark Ireland 2. Scapular Muscles (Fig 8 Gray’s 7.45) Connecting Scapula to Arm (Anterior View) Fig 8 Muscle Origin Insertion Innervation Action subscapularis subscapular lesser tubercle of upper and lower medial rotation of fossa humerus subscapular nn. arm Gross Anatomy: Pectoral & Axilla I Page 10 of 17 Dr. Mark Ireland 3. Pectoral Muscles (Fig 9 Gray’s 7.41) Pectoral Muscles - Connecting Thoracic Wall to Arm or Scapula (Anterior View) Fig 9 Muscle Origin Insertion Innervation Action pectoralis major medial ½ of lateral lip of medial and flexion, clavicle, anterior intertubercular lateral pectoral adduction and surface of sulcus (also nn. medial rotation of sternum called crest of arm (note: p. the greater major does not tubercle) extend the flexed arm as in T. 7.3 of Gray’s) Gross Anatomy: Pectoral & Axilla I Page 11 of 17 Dr. Mark Ireland Pectoral Muscles (Fig 10 Gray’s 7.42) Connecting Thoracic Wall to Arm or Scapula (Anterior View Deep to P. Major) Fig 10 Muscle Origin Insertion Innervation Action pectoralis minor ribs 3-5 coracoid process medial pectoral pulls tip of n. shoulder down and protracts scapula subclavius first rib inferior surface n. to subclavius pulls tip of of clavicle shoulder down, pulls clavicle medially to stabilize sternoclavicular joint Gross Anatomy: Pectoral & Axilla I Page 12 of 17 Dr. Mark Ireland Pectoral Muscles (Fig 11 Netter 417) Connecting Thoracic Wall to Arm or Scapula (Anteromedial View) Fig 11 Muscle Origin Insertion Innervation Action serratus anterior lateral surface of costal surface of long thoracic n. protraction, upper 8-9 ribs medial scapular rotation and border depression of scapula Gross Anatomy: Pectoral & Axilla I Page 13 of 17 Dr. Mark Ireland IV. AXILLA – PART I 1. Definition - The axilla is a pyramidal shaped region located between the upper thorax and the proximal humerus. The axilla contains a neurovascular bundle composed of the axillary artery and veins (and their branches), the brachial plexus, lymph nodes, and fat. 2. Boundaries of the Axilla Fig 12 a. Axillary inlet or apex (Fig 12 Gray’s 7.40) – The inlet is bounded by the first rib, coracoid process and adjacent area of the anterior surface of the scapula, and the posterior edge of clavicle. Axillary vessels and the brachial plexus enter the axilla through the apex. Gross Anatomy: Pectoral & Axilla I Page 14 of 17 Dr. Mark Ireland Fig 13 b. Anterior wall (Fig 13 and 14 Gray’s 7.41 and 7.42) - pectoralis major and minor, subclavius and clavipectoral fascia Fig 14 Gross Anatomy: Pectoral & Axilla I Page 15 of 17 Dr. Mark Ireland Fig 15 c. Posterior wall (Fig 15 Gray’s 7.45) - subscapularis, teres major, and latissimus dorsi entear se d. Lateral wall (Fig 16 Gray’s 7.44) – The anterior and posterior walls converge on the intertubercular groove of the Fig 16 humerus. Associated with the intertubercular groove are portions of the biceps brachii and coracobrachialis muscles Gross Anatomy: Pectoral & Axilla I Page 16 of 17 Dr. Mark Ireland e. Medial wall (Fig 17 Fig 17 Netter 417) - first four ribs with their external intercostal muscles and the superior portion of the serratus anterior muscle Fig 18 f. Floor (Fig 18 Gray’s 7.47) – Composed of skin and axillary fascia. The base is convex superiorly (corresponds to the concavity of the armpit) due to the attachment of the clavipectoral fascia; anterior and posterior axillary folds Gross Anatomy: Pectoral & Axilla I Page 17 of 17 Dr. Mark Ireland Fig 20 WALLS OF THE AXILLA Fig 19 ANTERIOR WALL OF AXILLA