External IntercostalsOrigin—lower border of superior ribCourse—Inferior and towards sternumInsertion—upper border of rib belowAction—lift rib cage upward and outward by “fixing” upper rib and raising lower rib of pairInhalation (accessory muscles)LevatoresCostarumSerratus Posterior SuperiorPectoralis MajorPectoralis MinorSubclaviusSerratus AnteriorSternocleidomastoideusScalenesLevatoresCostarumAlso referred to as costal elevatorsOn posterior aspect of thoracic cageAppear to be continuation of external intercostalsOrigin—C7, T1-T11Course—inferior and lateralInsertion—posterior surface of rib just below (maybe 2 below)Action—elevate ribsLever: load arm is longSerratus Posterior SuperiorSerrated knife (zig zag)on superior posterior aspect of thoracic cageOrigin – C7, T1‐T3Course – inferior and lateralInsertion – ribs 2 – 5 near angleAction – thought to elevate ribs 2 ‐ 5Lever system? DisadvantageApplying force to 4 parts but has to work on 12 ribsNo significant effect on elevating/expandingPectoralis Majorlarge fan shaped muscle on upper anterior thoracic wallOrigin – humerus bone of upper armCourse – fans out widely across anteriorthoraxInsertion – upper costal cartilages, sternum, clavicleAction – with shoulder fixed, draw sternum & ribs superiorly and laterally (possible)more likely, rotate arm across thoraxPectoralis Minorlarge thin muscle lying deep to pectoralis major on upper thoracic wallOrigin – anterior surface of scapulaCourse – inferior and medialInsertion – anterior medial portion of ribs 3 ‐ 5Action – with scapula fixed, lift ribs 3 ‐ 5 (possible)more likely, shoulder extensorClass III leverSubclaviussmall narrow muscle under clavicleOrigin – underside of clavicle, near scapulaCourse – slightly inferior and medialInsertion – junction of rib 1 and its cartilageAction – with clavicle braced, lift rib 1 (possible)more likely, draw shoulder anteriorlySerratus Anteriorlarge thin muscle on side wall of thoraxOrigin – anterior surface of scapulaCourse – anterior, around side of rib cageInsertion – ribs 1 – 8 or 9, near costal cartilagesAction – with scapula braced, lift ribs 1‐ 8 or 9 (possible)fixate and protract scapulaSternocleidomastoideuslarge muscle on side of neckOrigin – skull, behind ear at mastoid processCourse – inferior and medial, in two divisionsInsertion – superior surface of clavicle and sternumAction – with head fixed, elevate sternumwith sternum fixed, flex skull towards torsoScalenesgroup of three muscles (anterior, medial, posterior) deep in neckOrigin – transverse processes of C2 – C7Course – inferior and slightly lateralInsertion – ribs 1 and 2Action – raise ribs 1 and 2CSD 3112 1st EditionLecture 8Outline of Last Lecture I. Respiratory PassageII. LungsIII. Pleural LinkageIV. MusculatureV. InhalationVI. Diaphragma. Sternal portionb. Costal portionc. Vertebral Portiond. Diaphragm Openingse. Diaphragm ActionOutline of Current Lecture VII. Respiratory System Anatomy cont.a. External Intercostalsb. Inhalationc. LevatoresCostarumd. Serratus Posterior Superiore. Pectoralisf. Subclaviusg. Serratus Anterior h. Sternocleidomastoideusi. ScalenesCurrent LectureThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute. External Intercostals- Origin—lower border of superior rib- Course—Inferior and towards sternum- Insertion—upper border of rib below- Action—lift rib cage upward and outward by “fixing” upper rib and raising lower rib of pair Inhalation (accessory muscles)- LevatoresCostarum- Serratus Posterior Superior- Pectoralis Major- Pectoralis Minor- Subclavius- Serratus Anterior- Sternocleidomastoideus- Scalenes LevatoresCostarum- Also referred to as costal elevators- On posterior aspect of thoracic cage- Appear to be continuation of external intercostals- Origin—C7, T1-T11- Course—inferior and lateral- Insertion—posterior surface of rib just below (maybe 2 below)- Action—elevate ribso Lever: load arm is longSerratus Posterior Superior- Serrated knife (zig zag)- on superior posterior aspect of thoracic cage - Origin – C7, T1‐T3 - Course – inferior and lateral - Insertion – ribs 2 – 5 near angle - Action – thought to elevate ribs 2 ‐ 5 o Lever system? Disadvantageo Applying force to 4 parts but has to work on 12 ribso No significant effect on elevating/expandingPectoralis Major- large fan shaped muscle on upper anterior thoracic wall - Origin – humerus bone of upper arm - Course – fans out widely across anterior - thorax - Insertion – upper costal cartilages, sternum, clavicle - Action – with shoulder fixed, draw sternum & ribs superiorly and laterally (possible) o more likely, rotate arm across thorax Pectoralis Minor- large thin muscle lying deep to pectoralis major on upper thoracic wall - Origin – anterior surface of scapula - Course – inferior and medial- Insertion – anterior medial portion of ribs 3 ‐ 5 - Action – with scapula fixed, lift ribs 3 ‐ 5 (possible) - more likely, shoulder extensor o Class III lever Subclavius- small narrow muscle under clavicle - Origin – underside of clavicle, near scapula - Course – slightly inferior and medial - Insertion – junction of rib 1 and its cartilage - Action – with clavicle braced, lift rib 1 (possible) o more likely, draw shoulder anteriorly  Serratus Anterior- large thin muscle on side wall of thorax - Origin – anterior surface of scapula - Course – anterior, around side of rib cage - Insertion – ribs 1 – 8 or 9, near costal cartilages - Action – with scapula braced, lift ribs 1‐ 8 or 9 (possible) o fixate and protract scapula Sternocleidomastoideus- large muscle on side of neck - Origin – skull, behind ear at mastoid process - Course – inferior and medial, in two divisions - Insertion – superior surface of clavicle and sternum - Action – with head fixed, elevate sternum o with sternum fixed, flex skull towards torso Scalenes- group of three muscles (anterior, medial, posterior) deep in neck - Origin – transverse processes of C2 – C7 - Course – inferior and slightly lateral - Insertion – ribs 1 and 2 - Action – raise ribs 1 and 2