Pectoral region and breast

Question 1

What is the function of the clavicle?

Answer 1

• Connects the upper limb to the trunk.
• Serves as a moveable, crane-like strut from which the scapula and free limb are suspended, keeping them away from the trunk for maximum freedom of motion.
• Allows the scapula to move on the thoracic wall at the scapulothoracic joint, increasing the range of motion of the limb.
• Forms one of the bony boundaries of the cervico-axillary canal, protecting the neurovascular bundles supplying the upper limb.
• Transmits shocks from the upper limb to the axial skeleton.

Question 2

Describe the shape and structure of the clavicle.

Answer 2

• Shaft of the clavicle has a double curve (S-shaped) in the horizontal plane.
• Medial part of the shaft is convex anteriorly.
• Lateral part of the shaft is concave anteriorly.
• The clavicle is a long bone with no medullary (marrow) cavity, consisting of trabecular (spongy) bone with a shell of compact bone.

Question 3

What are the two ends of the clavicle and where do they articulate?

Answer 3

• Sternal end: Enlarged and triangular, articulates with the manubrium of the sternum at the sternoclavicular (SC) joint.
• Acromial end: Flat, articulates with the acromion of the scapula at the acromioclavicular (AC) joint.

Question 4

What are the key landmarks on the clavicle?

Answer 4

• Conoid tubercle: Near the acromial end, attachment to the conoid ligament (part of the coracoclavicular ligament).
• Trapezoid line: Attachment of the trapezoid ligament (lateral part of the coracoclavicular ligament).
• Subclavian groove: In the medial third of the shaft, attachment of the subclavius muscle.
• Impression for the costoclavicular ligament: Rough, depressed oval area near the medial end, attachment for the ligament binding the first rib to the clavicle.

Question 5

What is the role of the clavicle in terms of movement and joint types?

Answer 5

• The clavicle forms a physiological joint where movement occurs between musculoskeletal structures.
• It forms an anatomical joint at the sternoclavicular (SC) and acromioclavicular (AC) joints, where movement occurs between directly articulating skeletal elements.

Question 6

Describe the superior and inferior surfaces of the clavicle.

Answer 6

• Superior surface: Smooth, lies just deep to the skin and platysma muscle in the subcutaneous tissue.
• Inferior surface: Rough, with strong ligaments binding it to the first rib near its sternal end and suspending the scapula from its acromial end.

Question 7

How does the curvature of the clavicle affect its function?

Answer 7

The curvatures of the clavicle increase its resilience, helping it absorb and transmit forces from the upper limb to the axial skeleton.

Question 8

Describe the scapula’s general structure and location.

Answer 8

• The scapula is a triangular, flat bone.
• It lies in the posterolateral aspect of the thorax, overlying the 2nd to 7th ribs.

Question 9

What are the features of the scapula’s posterior surface?

Answer 9

• The posterior surface is convex.
• It is unevenly divided by a thick projecting ridge called the spine of scapula into:
1. Supraspinous fossa (smaller)
2. Infraspinous fossa (larger)

Question 10

What is found on the costal surface of the scapula?

Answer 10

• The costal surface is concave and forms the subscapular fossa, which is large and serves as a surface for muscle attachment.

Question 11

What are the main landmarks of the scapula?

Answer 11

• Body of scapula: Thin, triangular, translucent superiorly and inferiorly to the spine, with thicker borders (especially the lateral border).
• Acromion: Flat, expanded lateral continuation of the spine, forms the subcutaneous point of the shoulder, and articulates with the acromial end of the clavicle.
• Deltoid tubercle: Medial attachment of the deltoid muscle on the scapular spine.
• Spine of scapula: Acts as a lever for the trapezius muscle, together with the acromion.

Question 12

Describe the glenohumeral (shoulder) joint and its relationship with the scapula.

Answer 12

• The AC joint is lateral to the mass of the scapula and its attached muscles.
• The shoulder joint, where these muscles operate, is almost directly inferior to the AC joint.
• The scapular mass is balanced by the free limb, with the CC ligament acting as the balancing point between the two masses.

Question 13

What is the function and structure of the glenoid cavity?

Answer 13

• Located on the superolateral surface of the scapula.
• It receives and articulates with the head of the humerus at the shoulder joint.
• The glenoid cavity is a shallow, concave, oval fossa, smaller than the head of the humerus, serving as a socket for it.

Question 14

What is the coracoid process and its function?

Answer 14

• The coracoid process is beak-like, located superior to the glenoid cavity.
• It projects anterolaterally, resembling a bent finger towards the shoulder.
• The “knuckle” provides inferior attachment for the passively supporting CC ligament.

Question 15

Describe the scapula’s borders and angles.

Answer 15

• Borders:
o Medial border: Runs parallel to and lateral to the spinous processes of the thoracic vertebrae.
o Lateral border (axillary border): Runs superolaterally from the inferior angle toward the apex of the axilla, composed of a thick bar of bone to prevent buckling.
o Superior border: The thinnest and shortest border, marked by the suprascapular notch where it joins the base of the coracoid process.
• Angles:
o Superior, lateral, and inferior angles.

Question 16

What is the primary function of the scapula?

Answer 16

The scapula allows considerable movement on the thoracic wall at the physiological scapulothoracic joint, providing the base from which the upper limb operates and is able to move freely.

Question 17

What type of joint is the sternoclavicular (SC) joint and what is its function?

Answer 17

• The SC joint is a saddle-type synovial joint that functions like a ball-and-socket joint.
• It serves as the only articulation between the upper limb and the axial skeleton.

Question 18

How is the articular disc in the SC joint structured and what is its function?

Answer 18

• The articular disc divides the joint into two compartments.
• It is attached by the anterior and posterior sternoclavicular ligaments, thickenings of the fibrous layer of the joint capsule, and the interclavicular ligament.
• The disc serves as a shock absorber for forces transmitted from the upper limb.

Question 19

What are the articular surfaces of the SC joint?

Answer 19

• The sternal end of the clavicle articulates with:
o The manubrium of the sternum.
o The 1st costal cartilage.

Question 20

Describe the joint capsule of the SC joint.

Answer 20

• The joint capsule surrounds the SC joint, including the epiphysis at the sternal end of the clavicle.
• It attaches to the margins of the articular surfaces, including the periphery of the articular disc.
• The synovial membrane lines the internal surface of the fibrous layer of the joint capsule, extending to the edges of the articular surfaces.

Question 21

What ligaments reinforce the SC joint and what are their functions?

Answer 21

• Anterior and posterior sternoclavicular ligaments: Reinforce the joint capsule anteriorly and posteriorly.
• Interclavicular ligament: Strengthens the capsule superiorly and is also attached to the superior border of the manubrium.
• Costoclavicular ligament: Anchors the inferior surface of the sternal end of the clavicle to the first rib and its costal cartilage, limiting the elevation of the pectoral girdle.

Question 22

What is the movement range and type of movement at the SC joint?

Answer 22

• The SC joint can be raised to approximately 60° when the limb is fully elevated.
• The clavicle rotates along its longitudinal axis during elevation via flexion.
• Movement anteriorly and posteriorly ranges from 25° to 30°.
• Circumduction is possible through the combination of these movements.

Question 23

What is the blood supply to the SC joint?

Answer 23

• The SC joint is supplied by the internal thoracic and suprascapular arteries.

Question 24

What is the innervation of the SC joint?

Answer 24

• The SC joint is innervated by branches of the medial supraclavicular nerve and the nerve to the subclavius.

Question 25

What type of joint is the acromioclavicular (AC) joint and what is its articulation?

Answer 25

• The AC joint is a plane-type synovial joint. • The acromial end of the clavicle articulates with the acromion of the scapula. • Articular surfaces are covered in fibrocartilage and are separated by an incomplete wedge-shaped articular disc.

Question 26

Describe the joint capsule of the AC joint.

Answer 26

• The joint capsule is sleeve-like with a loose fibrous layer. • It is attached to the margins of the articular surfaces, and the synovial membrane lines the fibrous layer. • Although weak, the capsule is strengthened superiorly by fibers from the trapezius muscle.

Question 27

What ligaments reinforce the AC joint?

Answer 27

• Acromioclavicular ligament: Strengthens the AC joint superiorly, running from the acromion to the clavicle. • Coracoclavicular ligament: A pair of bands uniting the coracoid process of the scapula to the clavicle. o It consists of two ligaments:  Conoid ligament (medially): A vertical cone, with the apex inferiorly where it attaches to the root of the coracoid process, and a wide base attachment to the conoid tubercle on the inferior surface of the clavicle.  Trapezoid ligament (laterally): Nearly horizontal, attached to the superior surface of the coracoid process, extending laterally to the trapezoid line on the inferior surface of the clavicle.

Question 28

What is the blood supply to the AC joint?

Answer 28

• The AC joint is supplied by the suprascapular and thoraco-acromial arteries.

Question 29

What nerves innervate the AC joint?

Answer 29

• The AC joint is innervated by the lateral pectoral and axillary nerves (consistent with Hilton's law). • The cutaneous lateral suprascapular nerve also provides innervation, as no muscles cross the joint.

Question 30

What are the origins, insertions, innervations, and main actions of the pectoralis major (clavicular head)?

Answer 30

• Origin: Anterior surface of the medial half of the clavicle. • Insertion: Lateral lip of the intertubercular sulcus of the humerus. • Innervation: Lateral pectoral nerve (C5, C6). • Main Actions: o Adducts the humerus. o Medially rotates the humerus. o Draws the scapula anteriorly and inferiorly. o Flexes the humerus (when acting alone).

Question 31

What are the origins, insertions, innervations, and main actions of the pectoralis major (sternocostal head)?

Answer 31

• Origin: o Anterior surface of the sternum. o Superior 6 costal cartilages. o Aponeurosis of the external oblique muscle. • Insertion: Lateral lip of the intertubercular sulcus of the humerus. • Innervation: Medial pectoral nerve (C7, C8, T1). • Main Actions: o Adducts the humerus. o Medially rotates the humerus. o Draws the scapula anteriorly and inferiorly. o Extends the humerus from a flexed position (when acting alone).

Question 32

What are the origins, insertions, innervations, and main actions of the pectoralis minor?

Answer 32

• Origin: Upper margins and outer surfaces of the 3rd-5th ribs near their costal cartilages. • Insertion: Medial border and superior surface of the coracoid process of the scapula. • Innervation: Medial pectoral nerve (C8, T1). • Main Action: Stabilizes the scapula by drawing it inferiorly and anteriorly against the thoracic wall.

Question 33

What are the origins, insertions, innervations, and main actions of the subclavius?

Answer 33

• Origin: Junction of the 1st rib and its costal cartilage. • Insertion: Inferior surface of the middle third of the clavicle. • Innervation: Nerve to subclavius (C5, C6). • Main Action: Anchors and depresses the clavicle.

Question 34

What are the origins, insertions, innervations, and main actions of the serratus anterior?

Answer 34

• Origin: External surfaces of lateral parts of the 1st-8th ribs. • Insertion: Anterior surface of the medial border of the scapula. • Innervation: Long thoracic nerve (C5, C6, C7) (SALT). • Main Actions: o Protracts the scapula. o Rotates the scapula.

Question 35

What is the extent, enclosed structures, and piercing structures of the clavipectoral fascia (costocoracoid membrane)?

Answer 35

• Extent: From the clavicle superiorly to the axillary fascia inferiorly. • Enclosed Structures: o Subclavius muscle. o Pectoralis minor muscle. • Piercing Structures: o Medial and lateral pectoral nerves. o Pectoral branch of the thoraco-acromial artery. o Cephalic vein.

Question 36

What is the definition and function of the breast?

Answer 36

• The breast is a modified sweat gland. • Its function is to secrete milk. • It exists in both males and females: o Males: Rudimentary, with no alveoli and minimal adipose tissue. o Females: Underdeveloped before puberty, but grows after puberty and during pregnancy.

Question 37

What is the position, shape, and size of the breast?

Answer 37

• Shape: Variable, but base is fairly constant, typically hemispherical. • Position: o Vertically: 2nd to 6th ribs. o Horizontally: 4th intercostal cartilage from the sternum to near the midaxillary line. o Superolateral: Prolonged upwards and laterally towards the axilla (axillary tail of Spence). o Anatomical relationship:  Lies on pectoralis major.  Lies on serratus anterior and external oblique muscles.

Question 38

What are the components, borders, and surfaces of the breast?

Answer 38

• Mammary Papilla (Nipple): o Conical in shape. o Located at the 4th intercostal space in nulliparous females. o Variable in multiparous females. o Pink or light brown in color. • Areola: o Pigmented area at the base of the nipple. o Size increases and darkens with the 1st pregnancy and never returns to its original color. o Contains sebaceous glands of Montgomery, which are antibacterial and moisturizing. • Structure of the Breast: o Entire gland is located in the superficial fascia (retromammary space). o Lactiferous ducts give rise to buds that develop into 15-20 separate lobes of glandular tissue (tubulo-alveolar type). o Each lobe is separated by fibrous connective tissue. o Suspensory Ligaments of Cooper:  Fibrous processes from deep fascia to the skin and papilla.  These compartmentalize the lobes and support the glandular lobes.  Can become contracted by fibrosis in breast cancer, causing "pitting" (similar to the appearance of an orange). o Lactiferous Ducts: o Each lobule is drained by a lactiferous duct, which converges independently. o Lactiferous Sinus:  Each duct has a dilated portion beneath the areola where a small droplet of milk accumulates. o Terminal ducts are larger near the central end of each lobe and converge towards the nipple.

Question 39

What is the arterial supply to the breast?

Answer 39

• Perforating branches of the internal thoracic artery (from the subclavian artery) at the 2nd to 4th interspaces. • Perforating branches of the 3rd to 5th intercostal arteries. • Pectoral branches of the thoraco-acromial artery (from the 2nd part of the axillary artery). • Branches of the lateral thoracic artery (from the 2nd part of the axillary artery). • Branches of the subscapular artery (from the 3rd part of the axillary artery).

Question 40

What is the venous drainage of the breast?

Answer 40

• Anastomotic circle around the nipples (circulus venosus), draining into the axillary and internal thoracic veins via the intercostal veins.

Question 41

What is the lymphatic drainage of the breast?

Answer 41

• Axillary Group (drains 75%): o Lateral (humeral) nodes: Drain the upper limb, not the breast. o Pectoral (anterior) nodes: Found at the inferior border of pectoralis minor, drain central and lateral breast. o Subscapular (posterior) nodes: Along subscapular vessels and the posterior axillary fold. o Central nodes: Located in axillary fat, drain previous nodes. o Apical nodes (behind clavicle): Drain upper and peripheral breast parts, and the previous four nodes. o Ends in the subclavian lymph trunk, then:  Left side: Thoracic duct.  Right side: Subclavian vein or right jugular trunk. • Parasternal Group (drains 20%): o Located at the anterior ends of intercostal spaces along the internal thoracic artery, drains medial and some lateral breast aspects. o Carries cancer cells from one breast to another. • Intercostal Group (drains 5%): o Located along intercostal vessels. • Sappey's Plexus: o Drains the nipple and areola. • Abdominal Lymph Nodes: o Drain lymph from the skin covering the breast.

Question 42

What is the nerve supply to the breast?

Answer 42

• Anterior and lateral cutaneous branches of the 3rd to 6th intercostal nerves. o Convey sympathetic fibers to blood vessels and smooth muscles. • Nervous plexus around the nipple helps signaling suckling. • Nerves vulnerable during mastectomy include: o Intercostal brachial nerve. o Medial brachial cutaneous nerve. o Long thoracic nerve. o Thoracodorsal nerve. o Medial pectoral nerve.

Question 43

What are some applied anatomy considerations of the breast?

Answer 43

• Lymph Flow: o Important clinically for metastasis of breast cancer and interpreting node biopsy. • Cyst (Galactocele): o May develop due to blockage of lactiferous ducts. • Peau D'orange: o Pitting of hair follicles below the surrounding skin level, caused by blocked lymphatic drainage, leading to lymph stagnation and edema. • Skin Retraction: o Due to invasion of Cooper's ligaments, leading to dimpling. • Nipple Retraction: o Caused by extension of growth along the milk line ducts, leading to fibrosis and an indrawn nipple. • Amastia: o Absence of one or both breasts. • Polymastia: o Presence of extra mammary glands. • Polythelia: o Presence of extra nipples. • Gynecomastia: o Hypertrophy of male breast, often after puberty, due to hormonal imbalance (estrogens and androgens), sometimes with milk secretion.

Question 44

How does the humerus articulate with other bones?

Answer 44

• Proximally, the humerus articulates with the scapula at the glenohumeral joint. • Distally, it articulates with the radius and ulna at the elbow joint.

Question 45

What are the key features of the proximal end of the humerus?

Answer 45

• Head: Spherical, articulates with the glenoid cavity of the scapula. • Anatomical neck: Groove around the head separating it from the greater and lesser tubercles; indicates the attachment line of the glenohumeral joint capsule. • Surgical neck: Narrow part distal to the head and tubercles; common site of fracture.

Question 46

What are the major landmarks at the junction of the head and neck with the shaft of the humerus?

Answer 46

• Greater tubercle: Lateral margin of the humerus. • Lesser tubercle: Projects anteriorly. • Intertubercular sulcus (bicipital groove): Separates the tubercles and provides passage for the tendon of the long head of the biceps muscle.

Question 47

What are the two prominent features of the shaft of the humerus?

Answer 47

• Deltoid tuberosity: Lateral side for attachment of the deltoid muscle. • Oblique radial groove: Posterior side, for the radial nerve; contains the radial nerve and profunda brachii artery.

Question 48

What is the structure of the distal end of the humerus?

Answer 48

• Condyle: o Capitulum (lateral): For articulation with the head of the radius. o Trochlea (medial): Spool-shaped and pulley-like, for articulation with the trochlear notch of the ulna. • Fossae (superior to the trochlea): o Coronoid fossa (anterior): Receives the coronoid process of the ulna during full flexion of the elbow. o Olecranon fossa: Accommodates the olecranon of the ulna during full extension of the elbow. o Radial fossa (superior to the capitulum anteriorly): Accommodates the edge of the head of the radius during full flexion of the forearm.

Question 49

What type of joint is the glenohumeral joint?

Answer 49

• It is a ball and socket type synovial joint. • It is multiaxial and spheroidal.

Question 50

What are the articulating surfaces of the glenohumeral joint?

Answer 50

• The large, round humeral head articulates with the shallow glenoid cavity of the scapula. • The shallow glenoid cavity is slightly deepened by the fibrocartilaginous glenoid labrum. • Both articular surfaces are covered with hyaline cartilage.

Question 51

Describe the joint capsule of the glenohumeral joint.

Answer 51

• The joint capsule has a loose fibrous layer surrounding the glenohumeral joint. • It is attached medially to the margin of the glenoid cavity and laterally to the anatomical neck of the humerus. • The capsule is deficient inferiorly and not reinforced by the rotator cuff muscles. • The capsule is lax when the arm is adducted but taut when the arm is abducted. • Superiorly, the fibrous layer encloses the proximal end of the long head of the biceps brachii to the supraglenoid tubercle of the scapula.

Question 52

What are the two apertures in the capsule of the glenohumeral joint?

Answer 52

1. An opening between the tubercles of the humerus, allowing passage for the tendon of the long head of the biceps brachii. 2. An opening anteriorly and inferiorly to the coracoid process, allowing communication between the Subtendinous bursa of subscapularis and the synovial cavity of the joint.

Question 53

What are the ligaments associated with the glenohumeral joint?

Answer 53

1. Glenohumeral ligaments: o 3 fibrous bands reinforce the anterior aspect of the joint capsule. o They radiate laterally and inferiorly from the glenoid labrum at the supraglenoid tubercle and attach to the anatomical neck of the humerus. 2. Coracohumeral ligament: o A strong broad band passing from the base of the coracoid process to the anterior aspect of the greater tubercle of the humerus. 3. Transverse humeral ligament: o A broad fibrous band that runs obliquely from the greater to the lesser tubercle of the humerus. o It bridges the intertubercular sulcus and holds the synovial sheath and tendon of the biceps brachii in place. 4. Coracoacromial ligament: o Spans between the inferior surface of the acromion and the lateral border of the coracoid process. o Forms a protective arch over the humeral head, preventing superior displacement from the glenoid cavity.

Question 54

What are the bursae associated with the glenohumeral joint?

Answer 54

1. Subtendinous bursa of subscapularis: o Located between the tendon of subscapularis and the neck of the scapula. o Protects the tendon. 2. Subacromial (subdeltoid) bursa: o A large bursa located under the coracoacromial ligament and deltoid muscle.

Question 55

What are the blood supply and innervation of the glenohumeral joint?

Answer 55

• Blood supply: o Anterior and posterior circumflex humeral arteries. o Branches of the suprascapular artery. • Innervation: o Suprascapular, axillary, and lateral pectoral nerves.

Question 56

What is the role of the rotator cuff muscles in the stability of the glenohumeral joint?

Answer 56

• The rotator cuff muscles provide strong lateral stability and stabilize the head of the humerus in the glenoid cavity. • The muscles include: o Supraspinatus o Infraspinatus o Teres minor o Subscapularis

Question 57

What factors contribute to the stability of the glenohumeral joint?

Answer 57

1. Glenoid labrum: Increases concavity. 2. Coracoacromial arch: Prevents upward dislocation. 3. Tendon of the long head of biceps: Provides superior support. 4. Long head of triceps: Provides inferior support during abduction. 5. Ligaments: Contribute to joint stability. 6. Rotator cuff muscles: Provide strong lateral stability.

Question 58

What is the most frequent type of dislocation of the glenohumeral joint?

Answer 58

• The glenohumeral joint is most frequently dislocated inferiorly, as the inferior aspect is devoid of muscles.

Question 59

What nerve is prone to injury in shoulder dislocations?

Answer 59

• The axillary nerve is prone to tear at the surgical neck of the humerus, especially in relation to the inferior aspect of the articular capsule.

Question 60

What is the origin, insertion, innervation, and action of the trapezius muscle?

Answer 60

• Origin: o Medial third of the superior nuchal line o External occipital protuberance o Nuchal ligament o Spinous processes of C7-T12 vertebrae • Insertion: o Lateral third of the clavicle o Acromion and spine of scapula • Innervation: o Spinal accessory nerve (CN XI) (motor fibers) o C3, C4 (pain and proprioceptive fibers) • Action: o Descending part: Elevates the scapula o Ascending part: Depresses the scapula o All parts retract the scapula o Ascending and descending parts: Rotate the glenoid cavity superiorly.

Question 61

Flashcard 61 Q: What is the origin, insertion, innervation, and action of the latissimus dorsi muscle?

Answer 61

* Origin: o Spinous processes of the inferior 6 thoracic vertebrae o Thoracolumbar fascia o Iliac crest o Inferior 3/4 ribs * Insertion: o Floor of the intertubercular sulcus of the humerus * Innervation: o Thoracodorsal nerve (C6, C7, C8) * Action: o Extends, adducts, and medially rotates the humerus o Raises the body towards the arms during climbing

Question 62

Flashcard 62 Q: What is the origin, insertion, innervation, and action of the levator scapulae muscle?

Answer 62

* Origin: o Posterior tubercles of transverse processes of C1-C4 vertebrae * Insertion: o Medial border of scapula superior to the root of the scapular spine * Innervation: o Dorsal scapular nerves (C4, C5) o Cervical nerves (C3, C4) * Action: o Elevates the scapula o Rotates the glenoid cavity inferiorly

Question 63

Flashcard 63 Q: What is the origin, insertion, innervation, and action of the rhomboid minor and major muscles?

Answer 63

* Origin: o Minor: Nuchal ligament, spinous processes of C7 and T1 vertebrae o Major: Spinous processes of T2-T5 vertebrae * Insertion: o Minor: Smooth triangular area at the medial end of scapular spine o Major: Medial border of the scapula from the level of spine to inferior angle * Innervation: o Dorsal scapular nerve (C4, C5) * Action: o Retracts the scapula o Rotates the glenoid cavity inferiorly o Fixes the scapula to the thoracic wall

Question 64

Flashcard 64 Q: What is the origin, insertion, innervation, and action of the deltoid muscle?

Answer 64

* Origin: o Lateral third of clavicle o Acromion and spine of scapula * Insertion: o Deltoid tuberosity of humerus * Innervation: o Axillary nerve (C5, C6) * Action: o Clavicular (anterior) part: Flexes and medially rotates the arm o Acromial (middle) part: Abducts the arm o Spinal (posterior) part: Extends and laterally rotates the arm

Question 65

Flashcard 65 Q: What is the origin, insertion, innervation, and action of the supraspinatus muscle?

Answer 65

* Origin: o Supraspinatus fossa of scapula * Insertion: o Superior facet of greater tubercle of humerus * Innervation: o Suprascapular nerve (C4, C5, C6) * Action: o Initiates and assists deltoid in abduction of the arm o Acts with rotator cuff muscles

Question 66

Flashcard 66 Q: What is the origin, insertion, innervation, and action of the infraspinatus muscle?

Answer 66

* Origin: o Infraspinatus fossa of scapula * Insertion: o Middle facet of greater tubercle of humerus * Innervation: o Suprascapular nerve (C5, C6) * Action: o Laterally rotates the arm o Acts with rotator cuff muscles

Question 67

Flashcard 67 Q: What is the origin, insertion, innervation, and action of the teres minor muscle?

Answer 67

* Origin: o Middle part of lateral border of scapula * Insertion: o Inferior facet of greater tubercle of humerus * Innervation: o Axillary nerve (C5, C6) * Action: o Laterally rotates the arm o Acts with rotator cuff muscles

Question 68

Flashcard 68 Q: What is the origin, insertion, innervation, and action of the teres major muscle?

Answer 68

* Origin: o Posterior surface of inferior angle of scapula * Insertion: o Medial lip of intertubercular sulcus of humerus * Innervation: o Lower subscapular nerve (C5, C6) * Action: o Adducts the arm o Medially rotates the arm

Question 69

Flashcard 69 Q: What is the origin, insertion, innervation, and action of the subscapularis muscle?

Answer 69

* Origin: o Subscapular fossa (most of the anterior surface of scapula) * Insertion: o Lesser tubercle of humerus * Innervation: o Upper and lower subscapular nerves (C5, C6, C7) * Action: o Medially rotates the arm o Helps hold the head of the humerus in the glenoid cavity ________________________________________

Question 70

Flashcard 70 Q: What is the primary function of the rotator cuff muscles (SITS)?

Answer 70

* The primary function of the SITS muscles is to hold the humeral head in the glenoid cavity of the scapula.

Question 71

Flashcard 71 Q: What are the boundaries of the triangle of auscultation? A:

Answer 71

* Superior horizontal border of latissimus dorsi * Medial border of scapula * Inferolateral border of trapezius

Question 72

What arteries contribute to the anastomosis of the scapula?

Answer 72

* Transverse cervical artery (from thyrocervical trunk of subclavian artery) o Gives off the dorsal scapular artery * Suprascapular artery (from thyrocervical trunk) * Subscapular artery (from axillary artery) o Divides into circumflex scapular artery and thoracodorsal artery

Question 73

What is an anastomosis in vascular anatomy?

Answer 73

* An anastomosis is the connection of two or more vessels, usually between multiple branches of an artery, providing numerous potential detours if the pathway is obstructed.

Question 74

What are the boundaries and contents of the quadrangular space?

Answer 74

* Boundaries: o Superior: Teres minor o Inferior: Teres major o Lateral: Surgical neck of humerus o Medial: Long head of triceps * Contents: o Axillary nerve o Posterior circumflex humeral artery

Question 75

: What are the boundaries and contents of the triangular space (upper)?

Answer 75

* Boundaries: o Superior: Teres minor o Inferior: Teres major o Lateral: Long head of triceps * Contents: o Circumflex scapular artery

Question 76

Flashcard 76 Q: What are the boundaries and contents of the triangular interval (lower)?

Answer 76

* Boundaries: o Superior: Subscapularis (anteriorly) and teres major (posteriorly) o Medial: Long head of triceps o Lateral: Humerus * Contents: o Radial nerve o Profunda brachii vessels