Anterior Thoracic Wall Anatomy PDF

TOTAL PAGES: (9) TOPIC 13: ANTERIOR THORACIC WALL seen traversing the area of the nipple all ANTERIOR THORACIC WALL LONGITUDINAL LINES...

TOTAL PAGES: (9) TOPIC 13: ANTERIOR THORACIC WALL seen traversing the area of the nipple all ANTERIOR THORACIC WALL LONGITUDINAL LINES the way down to the pelvis 4. Parasternal line (blue) ANTERIOR THORACIC WALL POSTERIOR CHEST SIDE LATERAL CHEST SIDE 8. Scapular line (blue) ANTERIOR CHEST SIDE equal to your midclavicular line 5. Anterior Axillary Line 1. Midsternal Line divides the posterior chest wall into two seen dividing the anterior chest into two 6. Posterior axillary line unequal halves equal sides 7. Midaxillary line 9. Paravertebral line (yellow) 2. Lateral sternal line (red) Point of reference: axilla 10. Spinal line (red) 3. Mammary line (Midclavicular line) From the axilla all the way down to the pelvis both on the left and right side; divides reference when we are doing surgery in the chest wall into two unequal halves axillary area point of reference: midpoint of clavicle 1 DAVID LOPEZ  ANTERIOR THORACIC WALL ANTERIOR THORACIC WALL ANTERIOR THORACIC WALL STERNUM Jugular notch Manubrium ○ broadest part ○ 3 Notches: 2 clavicular notch 1 suprasternal (jugular notch) BONY THORAX Sternal Angle ○ a.k.a. Angle of Louis of Ludwig Thorax ○ attachment of 2nd rib RIBS ○ region of the body between the neck ○ where manubrium and body meet Body of Sternum Ribs (Costae) and the abdomen ○ consists of 4 sternebrae True Ribs Jugular notch Xiphoid Process ○ Vertebrosternal ribs ○ is in the same horizontal plane as the ○ smallest, diamond shaped ○ 1st 7 pairs of ribs lower border of the body of the second ○ directly connect to sternum via your thoracic vertebra (T2) cartilages False Ribs The sternal angle corresponding to the second costal Vertebrochondral cartilage is at the level opposite the intervertebral disc ○ 8th-10th ribs between the fourth and fifth thoracic vertebrae is so ○ cartilages will join the cartilage of rib 7 readily found that is used as a starting-point from which before attaching tothe sternum to count the ribs Vertebral Ribs ○ 11th-12th ribs = Floating ribs The 7th & 8th ribs are the longest 2 DAVID LOPEZ  ANTERIOR THORACIC WALL ANTERIOR THORACIC WALL SUPERIOR THORACIC APERTURE TYPICAL RIBS 1. Head ATYPICAL RIBS SUPERIOR THORACIC APERTURE 2. Neck 1st, 2nd, 10th, 11th & 12th ribs Boundaries 3. Tubercle First Rib highest, shortest, broadest, and most Posteriorly T1 vertebral body and costovertebral 4. Costal Angle sharply curved rib. joints (RED) 3rd to 9th ribs Angle coincides with its tubercle Laterally First ribs and their costal cartilages has head, neck, tubercle and shaft Articulates with one vertebra (BLUE) head has 2 facets connects to two adjacent Has Lisfranc tubercle attachment of Anteriorly Superior border of the manubrium vertebra scalenus anterior (BLACK) Tubercle connects to transverse processHas rounded shaft superiorly and sharp edge Second rib Tubercle is lateral to its angle inferiorly - has costal groove Has an attachment to posterior scalene 3 DAVID LOPEZ  SUPERIOR THORACIC APERTURE SUPERIOR THORACIC APERTURE INFERIOR THORACIC APERTURE STRUCTURES THAT PASS THROUGH S.T.A Trachea Esophagus Thoracic duct Apices of Lungs Nerves Phrenic Nerve SIBSON’S FASCIA Vagus Nerve a.k.a the Sibson fascia, cervicothoracic fascia Recurrent laryngeal nerves or costovertebral fascia Sympathetic trunks suprapleural membrane Arteries dense fascial layer that is attached to the inner L/R Arteries border of the first rib and costal cartilage Common carotid Arteries anteriorly Left Subclavian Arteries C7 transverse process posteriorly Veins Internal jugular veins DIAPHRAGM the mediastinal pleura medially Diaphragm of Thoracic Inlet brachiocephalic veins Origin Sternal (xiphoid process) ○ Plane of Inlet - 45’ subclavian veins Costal (lower 6 costal cartilages) Lymph nodes and Lymphatic Vessels Crura (right and left) Ligaments (lumbocostal arches) 4 DAVID LOPEZ  ○ Lateral arcuate (quadrat lumborum) These are called atypical ribs, because similar to the first There are 11 intercostal spaces. The upper 9 intercostal ○ Medial arcuate (psoas muscles) rib, The head of these ribs only articulate with one spaces are closed. Because anteriorly, they are closed vertebra. by the costal cartilages of the ribs. Insertion Central tendon Nerve Phrenic nerve (C3,C4,C5) The 11th and 12th rib have no neck and no tubercle. The widest intercostal space occurs in the 3rd intercostal Arterial Supply Meaning these ribs do not articulate with the transverse area. The intercostal space is wider during inspiration Pericardiophrenic artery (superior phrenic artery) process of the 11th and 12th thoracic vertebra Inferior phrenic artery INTERCOSTAL SPACES Musculophrenic artery Intercostal arteries INTERCOSTAL SPACES Foramina Aortic Hiatus (T12) ○ Aorta ○ Thoracic Duct ○ Azygos Vein Esophageal Hiatus (T10) ○ R & L vagus nerve ○ Esophageal branches of left gastric artery Inferior Vena Cava Hiatus (T8) ○ IVC ○ Right phrenic nerve ○ Lymphatic vessel EXTERNAL INTERCOSTAL MUSCLE Represented by the blue arrow. Attachment: Thoracic Vertebra. Once it reaches BONY THORAX the junction between the junction between the RIBS (COSTAE) ribs and costal cartilage (broken red line), the ATYPICAL RIBS muscle now becomes the Anterior intercostal a. 10th Ribs membrane (white arrow) One facet in its head Anterior intercostal membrane- touches the Uncertain rib: It may be a floating rib or lateral side of the sternum. This membrane is attached with the 9th rib with a cartilage. transparent and you can see the fiber of the b. 11th Ribs internal intercostal muscle. Its direction is Single facet in its head forward, but upward WHAT IS IT? Have no neck nor tubercle It is the space in between the ribs and the costal To remember: Costal Groove not distinct cartilages. External Intercostal muscle fibers: are directed anteriorly c. 12th Ribs It is here where the intercostal muscles are located: the and downward. One facet in its head Has no tubercle, angle and costal groove. external and internal intercostal muscles. 5 DAVID LOPEZ Internal Intercostal muscle fibers: are directed anteriorly, As you can see in the intercostal spaces, the and upward. muscle fibers are directed forward (anteriorly) and downward. Meaning these muscles are external intercostal muscles. INTERCOSTAL SPACES Origin: Inferior surface of the rib, above. Insertion: Upper surface of the rib, below Action: Elevate the rib in order to increase the diameter, anterior-posteriorly and vertically. It will now increase the volume of the thoracic cavity creating a lower thoracic pressure to favor inspiration. INTERNAL INTERCOSTAL MUSCLE Top Photo: The muscle fibers are directed forward and INTERCOSTAL SPACES upward. Anteriorly this muscle is attached to Lateral surface of the sternum. Posteriorly, once it reaches the angle of the rib, the muscle now becomes the Posterior Intercostal Membrane Origin: Upper surface of the rib (see blue line in second photo) Inserted: Lower surface of the rib (see blue line in second photo) Action: Pull the rib down. Doing so decreases the diameter, anterior-posteriorly and vertically. It will now decrease the volume of the thoracic cavity creating a higher thoracic pressure to favor expiration Take note of the difference of External and Intercostal muscle in regards to action. EXTERNAL INTERCOSTAL MUSCLE (CONT.) 6 DAVID LOPEZ  INTERCOSTAL SPACES B. Subcostalis- The second most constant muscle in this area (red arrow). Located at the postero-lateral surface of the thoracic wall. It arises from the rib, inserts at the rib above it. C. Innermost intercostal- Between these above mention muscles In regards to the innermost muscle of the thorax, as a group, we call the transverse thoracis. The sternocostalis and the subcostalis are located deeper than the neurovasculature of the thorax. The internal thoracic vessels (first photo) are anterior to this muscle. The intercostal neurovascular (second photo) structure is located more superficial to the subcostalis muscle. INTERCOSTAL SPACES INNERMOST INTERCOSTAL MUSCLE See yellow arrow in pictures Incomplete and variable Passes from ribs to ribs It is separated from the internal intercostal muscle by the intercostal nerve and vessels This is not present in all human beings. If it is present, it is sometimes incomplete. It passes through ribs to ribs and it is separated from internal intercostal muscle by the inner intercostal nerves and vessels. Once you open the thorax of the cadaver, and you look at the inner surface of the thoracic wall, you can appreciate the intercostal arteries, veins and nerves, that means that the cadaver has no innermost intercostal TRANSVERSE THORACIC MUSCLE muscle. A. Sternocostalis- Most constant muscle in this area (blue arrows). It is located at the inner This muscle covers these vessels, internally. surface of the anterior thoracic wall. It arises from the sternum, and inserts at the rib above it. 7 DAVID LOPEZ If you cannot see these vessels, that means that the cadaver has an innermost intercostal muscle. BLOOD VESSELS BLOOD VESSELS VENOUS DRAINAGE ANTERIOR INTERCOSTAL ARTERIES First artery that supplies the thoracic wall (See red arrow at right photo), These arteries are branches of the internal thoracic artery, which is a direct branch of the subclavian artery (black arrow at left photo). IN THE ANTERIOR THORACIC WALL Once the subclavian artery reaches the It will be draining to anterior intercostal vein that seventh rib, it now divides into the superior will eventually drain to the internal thoracic vein epigastric artery (light blue arrow) and POSTERIOR INTERCOSTAL ARTERIES or the upper 6th anterior intercostal vein musculophrenic artery (yellow arrow) Second artery that supplies the thoracic wall. The 8th, 9th, 10th, and 11th anterior intercostal From the 3rd posterior intercostal artery up to But for the lower 7 intercostal veins, it will drain artery, will no longer be a branch of the internal the 11th posterior intercostal artery and to the musculophrenic vein, which will thoracic artery but now becomes a branch of subcostal artery are direct branches of the eventually drain to the internal thoracic vein the musculophrenic artery Thoracic Aorta. (seen in the red arrow) (light blue arrow) and will drain to the The 1st and 2nd posterior intercostal artery are innominate veins branches of the Superior Intercostal Artery, which is a branch of the costocervical trunk of the subclavian artery 8 DAVID LOPEZ  IN THE POSTERIOR THORACIC WALL INTERCOSTAL NERVE INTERCOSTAL NERVE (CONT.) Hence, the muscles supplied by the intercostal and subcostal nerve are as follow: Supplies/innervates the external and internal intercostal muscle, transversus thoracis, sternocostalis, subcostalis, and innermost intercostal, levatores costarum; and for the abdomen: internal and transverse abdominis, rectus abdominis, and pyramidalis For the right posterior intercostal vein, it will drain to the azygos vein There are 12 pairs. The first 11 are called For the left posterior intercostal vein, it will drain to the intercostal nerves while the 12th one is called hemiazygos vein the subcostal nerve. Upper posterior intercostal vein, it will drain to the The typical nerve supplies the muscles and skin accessory hemiazygos vein, which will eventually drain of the intercostal spaces. into the azygos vein, and then will drain in the upper half Some of these nerves will have additional of the superior vena cava function. For example: The 1st intercostal nerve participates in the function of the brachial plexus forming the lower trunk The 2nd intercostal nerve crosses the axilla and supplies the posteromedial aspect of the arm as what you call the intercostobrachial nerve. The 3rd to 6th intercostal nerve are purely supplying the thoracic wall The 7th up to the 11th intercostal nerve does not only supply the intercostal structures but the anterior abdominal wall 9 DAVID LOPEZ