Thoracic Wall Anatomy PDF

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ThrillingPlatypus

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Menoufia University

Marwa Abdel-Samad Al-Gholam

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thoracic wall anatomy anatomy respiratory system medical education

Summary

This document contains lecture notes on thoracic wall anatomy, including objectives, contents, and detailed descriptions of ribs, intercostal muscles, and related structures. The presentation of the material is well-organized and includes anatomical diagrams, making it suitable for medical students.

Full Transcript

Thoracic wall anatomy by Marwa Abdel-Samad Al-Gholam MD anatomy and embryology Assistant professor of Anatomy and Embryology Menoufia University Objectives of the lecture Define the thoracic cage Identify typical and atypical ribs...

Thoracic wall anatomy by Marwa Abdel-Samad Al-Gholam MD anatomy and embryology Assistant professor of Anatomy and Embryology Menoufia University Objectives of the lecture Define the thoracic cage Identify typical and atypical ribs Describe origin, insertion, nerve supply and action of the intercostal muscle. Label the intercostal muscles Illustrate with a labeled diagram the intercostal muscles Contents: Overview of the thorax Thoracic cage Anatomy of the ribs Anatomy of the Intercostal muscles Thoracic Thoracic wall cavity T1 1st Thoracic rib inlet Thoracic T12 outlet Rib11,12 Xiphoid process Costal margin Anatomy of the ribs Classification according to the relation to the sternum Anatomy of the ribs Classification according to the morphological features Typical:3-9 Atypical: 1,2, 10-12. Features of typical ribs 1- Posterior end 2- Shaft (body) 3- Anterior end Shaft(body) Anterior end Vein Artery Nerve Parts of the sternum The angle of Louis (sternal angle) is the palpable anatomical feature formed from the manubriosternal junction. The sternal angle is an important clinical landmark for identifying many other anatomical points: It marks the point at which the costal cartilages of the second rib articulate with the sternum. This is particularly useful when counting ribs to identify landmarks as rib one is often impalpable. The counting of ribs is essential when one is attempting to make a thoracic incision Identification of the second rib and thus the second intercostal space inferiorly is also useful when auscultating heart sounds. It is at the level of the T4-T5 intervertebral disc. Muscles of the Thoracic Wall External intercostal muscle Origin: Inferior margin of rib above Insertion: Superior margin of rib below Parts: fleshy & membranous Internal intercostal Posterior intercostal membrane muscle Origin: floor of the costal groove of the rib above Insertion: Superior margin of the rib below Parts: fleshy & membranous Direction of fibers: Direction of fibers: downwards, downwards, forwards backwards and medially. and laterally. Sternocostalis muscle Insertion : posterior aspect of 2-6 costal cartilage Costal cartilage “ inner aspect” Direction of fibers: Sternocostalis Origin: body of the sternum, “posterior aspect” upwards and xiphoid process and costal cartilage (4-7) laterally. Innermost intercostal Muscle Origin: From the ridge above the costal groove of the rib above. Insertion: Into the upper margin of the rib below. Direction of fibers: the same as the internal intercostal muscle. Neurovascular bundle of thoracic wall. Notice: The muscle is essentially the deep part of the internal intercostal separated from it by the neurovascular bundle of thoracic wall. Subcostalis muscle Subcostalis Angle of the rib Origin : inner surface of the rib above near the angle Insertion : inner surface of the Direction of muscle fibers 2 nd rib below as internal intercostal Nerve supply: All muscles described are supplied by intercostal nerves of spaces concerned. Actions: 1. The external intercostal muscles elevate the ribs to increase the anteroposterior and transverse diameters of the thorax during inspiration. 2. The internal intercostal muscles have dual actions. i. The intercartilaginous fleshy parts act synergistically with external intercostal muscles and hence assist in inspiration. ii. The interosseous fleshy parts depress the ribs during forced expiration. 3. The sternocostalis muscles assist in pulling the second to sixth ribs inferiorly. 4. Collectively the intercostal muscles support the intercostal spaces. Action of intercostal muscles Increase the transverse Increase the diameter by anteroposterior diameter by the the false ribs true ribs Action of intercostal muscles External intercostal Internal intercostal muscle (interosseous) muscle Internal intercostal muscle (intracartilgenous)

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