Muscles involved in normal respiration Respiratory Block - Lecture 1 Color index: Important In male’s slides only In female’s slides only Extra information, explanation Doctors notes Editing File Objectives: ● Describe the components of the thoracic cage and their articulations. ● Describe in brief the respiratory movements. ● List the muscles involved in inspiration and in expiration. ● Describe the attachments of each muscle to the thoracic cage and its nerve supply. ● Describe the origin, insertion, nerve supply of diaphragm. INSPIRATORY MUSCLES EXPIRATORY MUSCLES !"#$%&'% Main Accessory Rib Depressor ()*'+&"(, -(,, +./0,$/ scalene Internal External muscles Diaphragm intercostal oblique pectoralis major Innermost Internal intercostal oblique external Pectoralis intercostal minor Transversus (Rib elevators) Subcostals abdominis serratus anterior Transversus Rectus Sternocleido-m thoracis abdominis astoid THORACIC CAGE: Has 2 apertures (openings) ● Conical in shape -Sternum -Costal Cartilages Inferior opening Superior opening (Inferior Thoracic (thoracic outlet) aperture) narrow, open, continuous Anteriorly with neck. wide, closed by obliquely placed facing upward and forward diaphragm Formed by Bounded by: Bounded by: 1-Anteriorly, 1-Anteriorly, Superior border of Xiphisternal joint -12 Thoracic -Ribs (12 pairs) the manubrium 2-laterally, Vertebrae -Intercostal sterni Curving costal 2-laterally, margin space Medial borders of 3-posteriorly, first rib Twelfth(12th) Posteriorly Laterally 3-posteriorly, thoracic vertebrae First(1rst) thoracic vertebrae Articulations Main joints found Based on the (details were in types of joints girls slides only) Vertebra (in boys slides) Sternocostal Secondary -Plane synovial joint mainly. Sternocostal cartilaginous: •1st costal cartilage: Costovertebral articulates with manubrium Manubriosternal joint, by a primary cartilaginous Xiphisternal joint and Intervertebral discs. joint Costochondral •2nd to 7th cartilages articulate with sternum by synovial joints interchondral Costovertebral Primary -Plane synovial joint Costovertebral -Between heads of ribs & cartilaginous: thoracic vertebrae. 1st Sternocostal joint, Costochondral joints and Interchondral joints. Costochondral Plane synovial -Cartilaginous joint Costochondral Costovertebral -Between the costal cartilage joints: Sternocostal joints and the rest of and the ribs Sternocostal joints. RESPIRATORY MOVEMENTS MOVEMENTS OF RIBS MOVEMENTS OF DIAPHRAGM (During Normal Inspiration) Inspiration PUMP HANDLE MOVEMENT Contraction (descent) of diaphragm Elevation of ribs Increase in antero-posterior diameter of Increase of vertical diameter of thoracic cavity thoracic cavity MED438 Notes: Both Normal and forced Inspiration are active (needs muscles action) Expiration BUCKET HANDLE MOVEMENT Relaxation (ascent) of Elevation of ribs Increase in diaphragm) lateral (transverse) diameter of MED438 Notes: -Normal Expiration is Passive thoracic cavity 1. Elastic recoil of lung 2.Relaxation of diaphragm & external intercostal (No muscles action) -Forced Expiration is active (needs muscles action) ORIGIN OF DIAPHRAGM: INSPIRATORY MUSCLES ● It has three origins: 1- Costal: lower 6 ribs and their costal cartilages 2-Sternal: xiphoid process of sternum Accessory Main (only during forced 3-Vertebral: upper 3 lumbar vertebrae inspiration) (right & left crus + arcuate ligaments) scalene muscles: Diaphragm Muscles attaching cervical vertebrae to first & second rib (Most important muscle) pectoralis major: attaching thoracic cage to INSERTION OF DIAPHRAGM upper limb external Pectoralis minor : attaching thoracic cage ● The Central Tendon intercostal to upper limb (Rib elevators) ● Lies at: the level of serratus anterior: attaching thoracic cage xiphisternal joint, at 9 th to upper limb thoracic Vertebra Sternocleidomastoid: Muscles attaching the Thoracic cage to the Skull THE DIAPHRAGM What is it? A musculotendinous partition between thoracic & abdominal cavity Structure Convex toward thoracic & concave toward abdominal cavity Attached to: Nerve supply Action Openings (Not in the slides but mentioned by the girls doctor cuz it’s important for the MCQ) -sternum, costal phrenic nerve contraction (descent) Caval aperture cartilages ,12th (C3,4,5), of diaphragm increase the inferior vena cava (the rib & lumbar penetrates the vertical diameter largest vein) passes at vertebrae(origin) diaphragm & of the thoracic cavity approximately vertebra T 8 innervates it (essential for normal -Fibers from abdominal breathing) Esophageal aperture converge to join surface The esophagus passes and inserted through it, at the level of into the central vertebra T 10. tendon(insertion) Aortic aperture The aorta (largest artery) passes posteriorly, at the lower level of vertebra T 12. External intercostal (inspiratory muscle ) Attachment : from lower border of superior (upper) rib to upper border of inferior (lower) rib Direction of fibers : -Downward,forward and medially. Nerve supply: -Intercostal nerves. Action: -Rib elevator (inspiratory) Note: The External intercostal muscle is the most superficial layer . Accessory inspiration muscles Muscle Scalene Pectoralis Muscles Major (Forced inspiration) (In forced inspiration) (In forced inspiration) Origin Transverse process of 1-sternum Pectoralis major Cervical vertebrae 2-costal cartilages 3-clavicle 1st rib Lateral lip of Bicipital Insertion (Scalenus anterior&medius) and groove of humerus 2nd rib(Scalenus posterior) Action Elevate 1st and 2nd Increases ribs antero-posterior diameter of thoracic cavity , when arm is fixed Sternocleidomastoid (Inspiratory muscles) Origin: -Sternal head: front of manubrium sterni -Clavicular head: medial third of clavicle. Insertion: -Mastoid process of the temporal bone and nuchal lines of occipital bone. Action: -Elevation of the manubrium -Elevation of the sternum and assists in forced inspiration. -Assists two muscles flex the neck. -Assists one muscle rotates the head of opposite side. Expiratory muscles -Two groups: 1-Rib depressors . 2- Anterior abdominal wall muscles . -Act only during forced expiration. (-Normal Expiration is Passive) 1-Rib depressors Muscles Internal Innermost Subcostal Transversus intercostal intercostal thoracis Direction Downward,Backward & laterally - - Nerve Intercostal nerves (ventral rami of T1-T11) Action Depression of the ribs . Picture Expiratory muscles Anterior abdominal wall(AAW) -Is formed of 3 layers of muscle of fibers running in different directions (to increase strength of anterior abdominal wall). -The 3 muscles form a sheath in which a fourth muscle lies(Rectus abdominis). -Muscles are attached to: Sternum, costal cartilages, ribs and hip bones. -The aponeurosis of the 3 muscles on both sides fuse in the midline to form linea alba . important note the median arcuate ligament “not related to the slide” attaches the right and left crus -Extra notes : -The AAW forms the anterior limit of the abdominal viscera. -It runs, superiorly from xiphoid process and costal cartilages of 7th,8th,9th and 10th ribs to iliac crest, inguinal ligament, anterior superior iliac spine, pubic tubercle, pubic crest and pubic symphysis inferiorly. Expiratory muscles 2-Anterior abdominal wall muscles -(Compression of abdominal viscera to help in ascent of diaphragm ) Internal External Transversus Rectus Oblique oblique abdominis abdominis Muscle (Middle (Outer layer) (Inner layer) layer) Downward & Upward & Transvers Vertical Direction medially medially lower 5 intercostal nerves (T7 – T11), subcostal nerve (T12) Nerve and first lumbar nerve (L1). (during forced expiration) Compression of abdominal Action viscera to help in ascent of diaphragm MCQ Q1: which one of the following best Q2: Which ONE of the following muscles Q3: Which one of the following muscles describes the Thoracic cage shape: depress the ribs ? used in forced inspiration? A.Conical A.Scalene A.External intercostal B.Cylindrical B.Pectoralis major B.Deltoid C.Triangular C.Internal intercostal C.Pectoralis major D.Irregular D.Transversus abdominis D.Transversus abdominis Q4: Which ONE of the following muscles Q5: What is the nerve supply of rib Q6: What is the action of subcostal is the outer layer of Anterior abdominal depressors muscles ? muscle ? wall muscles ? A. Intercostal nerve A.Rib depression A.External oblique muscle B.Subscapular nerve B.Rib elevation B.Internal oblique muscle C.Femoral nerve C.Compression of abdominal viscera 6:A C.Transversus abdominis muscle D.median nerve D.Increases antero-posterior diameter of 5:A D.Rectus abdominis muscle thoracic cavity 4:A 3:C 2:C 1:A answer key: answer MCQ Q7: which one of the following forms Q8: Which one is an accessory muscle of Q9: Which nerve supplies the Diaphragm? the Thoracic cage anteriorly? inspiration? A.phrenic nerve A.Sternum only A.Tansversus thoracis B.intercostal nerves B.Sternum and costal cartilages B.scalene muscle C.first lumbar nerve C.Ribs & intercostal spaces C.External intercostal muscle D.subcostal nerve D.Thoracic vertebrae D.Internal intercostal muscle Q10: How is the Superior opening Q11: How is the Inferior opening Q12: Which one of the following joints (thoracic outlet) bounded laterally? bounded anteriorly? involved in the thoracic cage articulation is a Plane synovial joints? A.First thoracic vertebrae A.Xiphisternal joint B.Second thoracic vertebrae B.Curving costal margin A.Manubriosternal joint C.Medial borders of first rib C.Twelve thoracic vertebrae B.Costochondral joints 12:D D.Superior border of the manubrium D.Sternocostal joints