Anterolateral_trunk_wall_2023.pptx

Session Goals 1. Understand the common structural elements of the thoracic and abdominal walls. 2. Understand how inspiration and exhalation are possible through the coordinated actions of structures making up and supplying the thoracic and abdominal walls and diaphragm. 3. Appreciate how the anter...

Session Goals 1. Understand the common structural elements of the thoracic and abdominal walls. 2. Understand how inspiration and exhalation are possible through the coordinated actions of structures making up and supplying the thoracic and abdominal walls and diaphragm. 3. Appreciate how the antero-lateral abdominal wall functions to produce intra-abdominal pressure changes. Learning Objectives 1. Describe the major functions of the anterolateral thoracic wall and the structural complexes involved in each; name, locate and describe the thoracic skeleton and its components; boundaries of the thoracic cage; and explain how to count ribs. Functions of the Anterolateral Thoracic Wall include: • containment/protection of vital viscera • site of attachment for upper limbs to trunk • participation in respiration • attachment site of mammary gland Thoracic Cage, boundaries Superior aperture boundaries: - First rib - Superior border of manubrium - First thoracic vertebra Inferior aperture boundaries: - Costal margin - Inferior sternum - 12th thoracic vertebra NOTE: the thoracic INLET = the inferior aperture the thoracic OUTLET =the superior Jugular notch Sternal angle Ribs True ribs: 1-7 Each articulates directly with the sternum by way of its costal cartilage False ribs: 8-12 Articulate with the sternum indirectly, by way of the costal cartilage of rib 7, to form the costal margin Floating ribs: 11 and 12 Possess a small costal cartilage at their tips, but do not articulate with the sternum A typical rib has a: Head Tubercle Neck Angle Body (shaft) Costal groove Costal cartilage (not shown) Atypical ribs: 1, 2, 11, and 12 Section through a rib Internal surface External surface Costo-vertebral articulations Facet for tubercle of rib -synovial joints where the rib articulates with its respective thoracic vertebra Facet for head of rib NOTE: each rib articulates with its respective thoracic vertebra at 2 places: 1. the head of the rib 2. the tubercle of the rib (except rib 12, which usually lacks a tubercle) tubercle, articulating with transverse process head, articulating with vertebral body (and) IV disc nteriorly, ribs 1-10 rticulate via costal cartilages First rib articulates with the manubrium via a fibrous joint Ribs 2-7 articulate with sternum via synovial joints ow do you count ribs? Thoracic Vertebrae, lateral view Posteriorly, begin with the vertebra prominens and count the spinous processes from there… ow do you count ribs? Anteriorly, begin at the sternal angle and count ribs inferiorly from there… Sternoclavicular joint Jugular notch From: Moore and Agur, 2007. Learning Objective 1: Application Describe the major functions of the anterolateral thoracic wall and the structural complexes involved in each; name, locate and describe the thoracic skeleton and its components; boundaries of the thoracic cage; and explain how to count ribs. Ask yourself: • What anterior landmark is essential to counting ribs on a patient? • What is the superior boundary of the thoracic cage? • How many articulations join the ribs to the axial skeleton, and what types of movements are possible at each. (HINT: these are not the same for all ribs…) Learning Objectives 2. Name, locate, and describe the layers of the anterolateral thoracic wall from superficial to deep (including the neurovascular plane) and their pattern of innervation and blood supply. Extrinsic Muscles of the Thoracic wall: pectoralis major & minor Extrinsic Muscle of the Thoracic wall: serratus anterior ribs 1-6 Antero-lateral Thoracic Wall, intrinsic muscles Intercostals = ‘between ribs’ Intercostal muscles consist of three layers, from superficial to deep: • external intercostal layer • internal intercostal layer • innermost intercostal layer  Note: each layer consists of muscle and membrane. From Basmajian, 1975 Intercostal muscles Note: the fibers of the external and internal intercostals are oriented perpendicular to each other. Observe that the fibers of the internal intercostal through the thin membrane of the external intercostal. Membrane of External intercostal Intercostal Muscles and NVB Vein Artery Nerve Anterior Thoracic Wall, Internal aspect (most anterior portion of innermost intercostals) Intrinsic Muscles of the Anterolateral Thoracic Wall Endothoracic Fascia -connective tissue lining the entire thoracic cavity, deep to the innermost intercostals -thin, except superiorly, where it thickens to form the supraplural membrane -important surgically, as it separates easily from the parietal pleura, forming a natural plane between the pleural cavities and the thoracic wall NOTE: the endothoracic fascia lies in the plane between the msculoskeletal portion of the thoracic walls and the Learning Objective 2: Application Name, locate, and describe the layers of the anterolateral thoracic wall from superficial to deep (including the neurovascular plane) and their pattern of innervation and blood supply. Ask yourself: • How would you characterize the most superficial muscles of the anterolateral thoracic wall? • What is the fiber direction of each of the intercostal layers? • Between what layers of intrinsic thoracic wall muscles is the neurovascular plane located? Learning Objectives 3. Describe the major functions of the anterolateral abdominal wall and the structural complexes involved in each; name, locate, and describe the layers of the anterior abdominal wall from superficial to deep (including the neurovascular plane) and name their correlates in the anterolateral thoracic wall. Functions of the Anterior Abdominal Wall include: • containment/protection for vital organs • expulsion/movement of GI, reproductive, and urogenital contents • point of exit for testes in males; round ligament of the uterus in females Dissection demonstrating The fatty layer (Camper’s) o subcutaneous fat and the superficial fascia or membranous layer (Scarpa’s fascia) in the anterior abdominal wall. Cross-section through superficial fascias of anterior abdominal wall. The *s mark a layer lacking in adipose known as the membranous layer, or Scarpa’s fascia. Note: the terminology still found in most texts still refers to the SAT of this region as ‘Camper’s Fascia.’ Lancerotto, et al.,2011 Surg Radiol Anat http://www.barralinstitute.com/articles/docs/abdominal_fascia%20stecco.pdf Elastic fibers in membranous layer of superficial fascia SAT=superficial adipose tissue DAT=Superficial fascia (aka: Scarpa’s fascia or membranous layer of superficial fascia). Lancerotto, et al.,2011 Surg Radiol Anat http://www.barralinstitute.com/articles/docs/abdominal_fascia%20stecco.pdf Boundaries and extent of the membranous layer (superficial fascia, aka, Scarpa’s fascia) in the anterior abdominal wall. Note: this fascial layer also covers the external genitalia, not illustrated here. Anterolateral Thoracoabdominal wall muscles Note: The layering and arrangement of the sheet muscles of the abdomen closely resembles that of the intercostals in the thoracic region. These are, after all, derived from a common muscular tunic of the embryonic trunk, which eventually becomes interrupted by ribs in the thoracic region during development. External oblique 1st muscle layer of antero-lateral abdominal wall (external abdominal oblique) The inferior border of the external oblique is the inguinal ligament. Indicates position of the inguinal ligament position of inguinal ligament A B Position of the Inguinal Ligament (seen externally as the thigh crease) A=anterior superior iliac spine; B= pubic tubercle 2nd muscle layer of antero-lateral abdominal wall (internal abdominal oblique) Internal oblique 3rd muscle layer of antero-lateral abdominal wall (transversus abdominis)  Note location of the neurovascular plane Transvers us abdomini s Transverse Section through left Abdominal Wall Note: endoabdominal fascia is given regional names. For example: where it covers the internal aspect of transversus abdominis it is known as transversalis fascia; where it covers psoas major, psoas fascia; where it courses over iliacus, iliacus fascia, etc. Learning Objective 3: Application Describe the major functions of the anterolateral abdominal wall and the structural complexes involved in each; name, locate, and describe the layers of the anterior abdominal wall from superficial to deep (including the neurovascular plane) and name their correlates in the anterolateral thoracic wall. Ask yourself: • What muscles assist in defecation? Micturiction (urination)? Parturition? How? Name them… • What is unique about the superficial fascia of the lower portion of the anterolateral abdominal wall? • Why is surgery through the midline of the anterior abdominal wall undesirable from a healing aspect? • What layers would, an incision placed above the inguinal ligament, a cm. from its lateral attachment, pass through before encountering peritoneum? Learning Objectives 4. Locate and describe the structure, function, innervation, of the rectus abdominis; the composition of the rectus sheath and its structural organization above and below the level of the umbilicus; the origin, course, and structures supplied by the inferior epigastric artery. he flat tendon of the external oblique is an xample of an aponeurosis. Each of the 3 sheet muscles of the anterolateral abdominal wall: external oblique, internal oblique, and transversus abdominis are fleshy laterally, then become aponeurotic anteriorly At the midline, where the aponeuroses from each side meet, their fibers interlace to form a vertical seam, the linea alba Linea alba. Aponeurosis of the external oblique. Rectus abdominis External oblique e the clear demarcation between the fleshy portion of the external oblique and ateral boundary of the rectus abdominis. Left anterior rectus sheath removed to reveal left rectus abdominis muscle Beil, p. 209 Note that the external oblique aponeurosis is more extensive inferiorly, where it forms the Anterior exposure of right rectus abominis muscle tendinous intersections Rectus abdominis Rectus abdominis UMMARY: Muscles of the Antero-lateral Abdominal Wall External Abdominal Oblique Note: all these muscles innervated by Origin: external surfaces of ribs 5-12 T 6/7-T11 intercostal nerves and by Insertion: linea alba; anterior superior iliac spinr, pubic tubercle, the subcostal nerve (T12) & lateral ½ of iliac crest Function: raise intra-abdominal pressure; flex and rotate trunk Internal Abdominal Oblique Origin: thoracolumbar fascia; anterior 2/3 of iliac crest Insertion: inferior border of ribs 10-12; linea alba; pectin pubis Function: raise intra-abdominal pressure Transversus abdominis Origin: internal aspect of costal cartilages of ribs 7-12; thoracolumbar fascia; iliac crest Insertion: linea alba; pectin pubis Function: raise intra-abdominal pressure Rectus abdominis Origin: pubic symphysis and pubic crest Insertion: xiphoid process and costal cartilages 5-7 Function: flex trunk; stabilize pelvis Laminar organization of the aponeurosis of External Oblique Isolated linea alba (all aponeuroses removed except at midline) Beil, p. 211 A B Internal Aspect of Anterior Abdominal Wall • The location where the rectus sheath becomes discontinuous posteriorly is the arcuate • The line.blood supply to the lower portion of the rectus abdominis is through the inferior epigastric artery. Collateral Arterial System of Anterior Abdominal Wall Inguinal ligament marking the boundary between the external iliac and femoral arteries. Note the inferior epigastric arising from the external iliac immediately before the vessel passes underneath the inguinal ligament. Learning Objective 4: Application Locate and describe the structure, function, innervation, of the rectus abdominis; the composition of the rectus sheath and its structural organization above and below the level of the umbilicus; the origin, course, and structures supplied by the inferior epigastric artery. Ask yourself: • What are the attachments of rectus abdominis and what does its contraction do? • How does the architecture of the rectus sheath differ above vs. below the umbilicus? • What two arteries anastomose on the posterior aspect of rectus abdominis? What is each a branch of?