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REVIEW OF ANATOMY UNDERLYING PROCEDURES USED IN EMERGENCY MEDICINE ANATOMY OF THORACIC WALL AND THORACOSTOMY Thoracostomy is the insertion of a tube into the pleural cavity. Thoracostomy is performed as a procedure to drain fluid or blood (hemothorax) or to remove air (pneumothorax) from the pleural cavity. Knowledge of the anatomy of the chest is necessary for accurate tube placement. Thoracostomy tube STRUCTURE OF ANTERIOR THORACIC WALL: MOST STRUCTURES ARE PALPABLE Rib 1 not palpable Rib 2 Suprasternal notch Manubrium Sternal angle Body of sternum costal cartilage Xiphoid process Rib 7 The anterior thoracic wall is formed by the ribs and sternum; ribs 1-7 attach to the sternum via costal cartilages; ribs 8-10 attach to the costal cartilages above; ribs 11-12 are floating (cannot be palpated) INTERCOSTAL MUSCLES AND COURSE OF INTERCOSTAL NERVES, ARTERIES AND VEINS Intercostal muscles Intercostal vein, artery, nerve External Intercostal Muscle Internal and Innermost Intercostal Muscles Three layers of intercostal muscles are found between the ribs (External, Internal and Innermost Intercostal Muscles) Intercostal veins, arteries and nerves course in the intercostal spaces. COURSE OF INTERCOSTAL NERVES, ARTERIES AND VEINS The intercostal nerves, arteries and veins course between the Internal and Innermost Intercostal muscles: Order: Superior to Inferior: vein, artery, nerve = VAN The bundles are found along the inferior margins of the ribs, often forming a groove in the rib. SENSORY INNERVATION AND DAMAGE TO INTERCOSTAL NERVE 1. Dermatome (= area of skin innervated by single spinal nerve) - in thorax dermatome map looks like stripes. OVERLAP OF DERMATOMES GREATEST ON TRUNK 2. Overlap - there is some overlap between adjacent dermatomes; overlap is greater on trunk than on extremities 3. Clinical signs of damage to intercostal nerve - damage (pressure) to a single spinal nerve or single dorsal root can produce pain in the skin of its dermatome. (Note: because of overlap of dermatomes in region of trunk, damage to a single intercostal nerve often will not produce loss of sensation (anesthesia); loss of sensation on skin of trunk will occur if two or more adjacent nerves are damaged. ANATOMY OF THE LARYNX AND AIRWAY OBSTRUCTION Obstruction of the upper airway can occur for a variety of reasons, including ingestion of food, anaphylactic shock and trauma. This can often be life threatening. Cricothyrotomy and tracheotomy establish an opening of the lower respiratory system in the neck, below the obstruction. This requires knowledge of the anatomy of the larynx. LARYNX: CARTILAGES Larynx consists of cartilages that are linked by membranes and joints Laryngeal Prominence Thyroid cartilage is shield shaped and sits above Cricoid Cartilage (ring shaped, cricoid = signet ring) Cricoid Cartilage is above trachea trachea Laryngeal Prominence or Notch = Adam’s Apple, more prominent in males LIGAMENTS OF LARYNX - link cartilages and attach it to hyoid bone Median Thyrohyoid Ligament Median Cricothyroid Ligament 1. Thyrohyoid Membrane links larynx to hyoid bone; Median Thyrohyoid Ligament - thickened midline part 2. Cricothyroid Membrane links thyroid to cricoid; Median Cricothyroid Ligament - thickened midline part 3. Cricotracheal ligament links Cricoid to first tracheal cartilage VI. LARYNX - ARTERIAL SUPPLY Sup. Laryngeal A. from Sup. Thyroid artery Inf. Laryngeal A. from Inf. Thyroid artery OBSTRUCTION OF LARYNX: TRACHEOTOMY open airway to lungs below obstructed larynx Tracheotomy - cut between first and second or second and third tracheal cartilages BLEEDING IS PROBLEM: MIDLINE THYROID VEINS 1) Sup. Thyroid vein follows artery 2) Middle Thyroid vein - to Int Jugular 3) Inf. Thyroid vein Both sides join at midline; drain to Left Brachiocephalic Vein CRICOTHYROTOMY - OPENING OF AIRWAY THROUGH CRICOTHYROID MEMBRANE Incision is made in midline through Cricothyroid membrane at Median Cricothyroid Ligament No major veins so bleeding is minimal Arteries and nerves are unaffected as they enter larynx from lateral and posterior sides. ANATOMY OF VENOUS SYSTEM AND CATHETER PLACEMENT The placement of flexible tubes into the circulatory system (catheterization) is now widely used in medicine in treatment and diagnosis. Central venous line Central venous lines are catheters placed into the venous system close to the heart. They can be used to rapidly and reliably administer drugs to the circulatory system and to the heart itself. The can also provide for sampling of blood when other veins are small (infants) Knowledge of anatomy of the venous system is essential in performing catheterization. OVERVIEW OF VENOUS RETURN TO THE HEART Right Brachiocephalic vein Superior Vena Cava Right Atrium Left Brachiocephalic vein All venous blood returns to the heart by entering the Right Atrium Inferior Vena Cava drains venous blood from below the diaphragm Superior Vena Cava drains venous blood from the head, upper extremities and thorax Superior Vena Cava is formed from the Right and Left Brachiocephalic Veins Inferior Vena Cava VESSELS DRAINING TO SUPERIOR VENA CAVA Right Subclavian vein Right Brachiocephalic vein Internal Jugular Veins The BRACHIOCEPHALIC VEINS are symmetrical Left (unlike the arteries from Subclavian the Aorta) vein Left Brachiocephalic vein Each brachiocephalic vein forms at the junction of the Internal Jugular and Subclavian veins at the base of the neck Superior Vena Cava Right Brachiocephalic vein Left Brachiocephalic vein INTERNAL JUGULAR VEIN - VENOUS DRAINAGE OF BRAIN AND DEEP STRUCTURES OF HEAD Superior Sagittal Sinus Cavernous Sinus Common Facial Vein INTERNAL JUGULAR VEIN INTERNAL JUGULAR VEIN - drains venous sinuses of brain - also veins of face and deep structures of head - Int. Jug. Vein forms at Jugular foramen of skull - Drains to Brachiocephalic vein PATTERN OF VENOUS DRAINAGE OF FACE AND HEAD: SUPERFICIAL VEINS Post. Auricular Sup. Temp. PATTERN OF VENOUS DRAINAGE 1. Superficial Temporal & Maxillary veins form Retromandibular Vein (RM) Max RM 2. Retromandibular Vein Divides into Ant. (AD) and Post. (PD) divisions AD EXTERNAL JUGULAR VEIN Common facial 3. Post. Division (PD) joins Post. Auricular V. to form External Jugular V.; drains to Subclavian V. PD Facial 4. Ant. Division (AD) joins Facial V. to form Common Facial V.; drains to Int. jugular V. Anterior jugular Vein External Jugular Vein ANTERIOR JUGULAR VEIN 5. Ant. Jugular V. forms from veins below mandible; drains to Ext. Jugular vein above clavicle LOCATION OF STRUCTURES IN NECK MAJOR LANDMARK: STERNO-CLEIDOMASTOID MUSCLE 0rigin - Two heads 1) Manubrium of sternum 2) Clavicle- medial 1/3 (cleido- means clavicle) STERNOCLEIDOMASTOID Insertion - Mastoid process of temporal bone Action - bilateral - Flex head; unilateral Rotate head, face is directed to opposite side Innervation - CN XI (Accessory n.) STERNOCLEIDOMASTOID Action on one side - rotate head, face is directed to opposite side LOCATION OF VEINS IN NECK: INTERNAL JUGULAR VEIN INTERNAL JUGULAR VEIN INTERNAL JUGULAR VEIN - courses in Carotid Sheath DEEP TO STERNOCLEIDOMASTOID MUSCLE STERNOCLEIDOMASTOID MUSCLE CUT STERNOCLEIDOMASTOID MUSCLE INTERNAL JUGULAR VEIN Carotid sheath contains Internal and Common Carotid Arteries, Internal Jugular Vein, Vagus Nerve COURSE OF VEINS IN NECK: EXTERNAL AND ANTERIOR JUGULAR VEINS ANTERIOR JUGULAR VEINS External Jugular Vein courses on surface of Sternocleidomastoid muscle; drains to Subclavian Vein EXTERNAL JUGULAR VEIN Anterior Jugular Veins course superficially in EXTERNAL anterior neck; drains to JUGULAR External Jugular Vein VEIN SUBCLAVIAN VEIN LOCATION OF VEINS: DEEP BRACHIAL VEINS AXILLARY VEIN clavicle cut DEEP BRACHIAL VEINS two large veins parallel BRACHIAL ARTERY in arm; also called Venae comitantes (accompanying veins) DEEP BRACHIAL VEINS drain to AXILLARY VEIN DEEP BRACHIAL VEINS SUBCLAVIAN VEIN AXILLARY VEIN becomes SUBCLAVIAN VEIN (at lateral border of rib 1) LOCATION OF VEINS: SUBCLAVIAN VEIN SUBCLAVIAN VEIN parallels SUBCLAVIAN ARTERY; clavicle both SUBCLAVIAN ARTERY AND VEIN are named for their course DEEP TO CLAVICLE SUBCLAVIAN ARTERY SUBCLAVIAN VEIN SURFACE RELATIONSHIPS OF INTERNAL JUGULAR AND SUBCLAVIAN VEINS INTERNAL JUGULAR VEIN 1- Courses deep to Sternocleidomastoid muscle INTERNAL JUGULAR VEIN 2- Vein is accessible through Sternal and Clavicular heads of Sternocleidomastoid SUBCLAVIAN VEIN - Courses posterior to clavicle, anterior to Rib 1. Accessible by needle placed 3- Superior to clavicle 4- Inferior to clavicle. SUBCLAVIAN VEIN