Contains macula, identical in structure and function to that of utricle Semicircular ducts a. Within semicircular canals b. Each has ampulla at one end c.
Ampullary crest in each ampulla senses movement of endolymph in plane of duct d. Detect rotational tilting movements of head Cochlear labyrinth Spiral ligament suspends cochlear duct from external wall of spiral canal Cochlear duct a.
Triangular in shape b. Filled with endolymph c. Spans spiral canal, dividing it into two channels, each filled with perilymph d. Two channels: scala tympani and scala vestibule, meet at apex of cochlea helicotrema e. Found on basilar membrane b. Covered by gelatinous tectorial membrane c. Contains hair cells-tips embedded in tectorial membrane d. Drains cerebral veins Confluence of sinuses sagittal sinus 2.
Contains arachnoid villi and granulations for reabsorption CSF Inferior sagittal Lower free margin falx cerebri Joins great cerebral vein sinus forming straight sinus Straight sinus Junction falx cerebri and Formed by union great cerebral vein with inferior sagittal Confluence of sinuses tentorium cerebelli sinus Transverse Lateral margin tentorium 1.
Passes laterally from confluence of sinuses Sigmoid sinus sinus cerebelli 2. Left is usually larger Sigmoid sinus S-shaped course in temporal Continuation transverse sinus Internal jugular vein and occipital bones Cavernous Superior surface of body of 1.
Receives superior and inferior ophthalmic and Superior and inferior sinus sphenoid, lateral to sella superficial middle cerebral veins and sphenoparietal petrosal sinuses turcica sinus 2.
CN V has three divisions: V1 and V2 are sensory, and V3 is both motor to skeletal muscle and sensory. The following table summarizes the types of fibers in each cranial nerve and where each passes through the cranium: Cranial nerves emerge through foramina or fissures in the cranium Twelve pairs Numbered in order of origin from the brain and brain stem, rostral to caudal Contain one or more of six different types of fibers Motor fibers to voluntary muscles Somatic motor fibers to striated muscles 1 a.
Orbit b. Tongue c. Carry sensation from viscera b. Thyrohyoid muscle b. Omohyoid b. Sternohyoid c. Usually one-sided and can affect a division of CN V, usually the mandibular, maxillary nerve. Pain can be triggered by touching a sensitive area "trigger point" The cause is not usually known Treatment is directed to controlling the pain. Ocular Nerve Palsy Alesion of the oculomotor nerve will paralyze all extraocular muscles except the lateral rectus and the superior oblique.
Ascends on pharynx b. Send branches to pharynx, prevertebral muscles, middle ear, and cranial meninges Superior thyroid a. Gives rise to superior laryngeal artery supplying larynx Lingual a.
Passes deep to hypoglossal nerve, stylohyoid muscle, and posterior belly of digastric b. Disappears beneath hyoglossus muscle and becomes deep lingual and sublingual arteries Facial a. Branches to tonsil, palate, and submandibular gland b. Hooks around middle of mandible and enters face Occipital a.
Passes deep to posterior belly of the digastric b. Grooves base of skull c. Supplies posterior scalp Posterior auricular a. Passes posteriorly between external acoustic meatus and mastoid process b.
Supplies muscles of region, parotid gland, facial nerve, auricle, and scalp Maxillary a. Larger of two terminal branches b. Branches supply external acoustic meatus, tympanic membrane, dura mater and calvaria, mandible, gingivae and teeth, temporal pterygoid, masseter, and buccinator muscles Superficial temporal a.
Smaller terminal branch b. Supplies temporal region of scalp Carotid Branch Course and Structures Supplied Superior thyroid Supplies thyroid gland, larynx, and infrahyoid muscles Ascending pharyngeal Supplies pharyngeal region, middle ear, meninges, and prevertebral muscles Lingual Passes deep to hyoglossus muscle to supply the tongue Facial Courses over the mandible and supplies the face Occipital Supplies SCM and anastomoses with costocervical trunk Posterior auricular Supplies region posterior to ear Maxillary Passes into infratemporal fossa described later Superficial temporal Supplies face, temporalis muscle, and lateral scalp page 79 page 80 Subclavian artery Branch of aortic arch on the left From brachiocephalic trunk on the right Enters neck between anterior and posterior scalene muscles Supplies upper limbs, neck and brain Divided for descriptive purposes into 3 parts, in relation to the anterior scalene muscle First part a.
Medial to the anterior scalene b. Has three branches Second part a. Posterior to the anterior scalene b. Has one branch Third part a. Lateral to anterior scalene b. Has one branch Subclavian Branch Course Part 1 Vertebral Ascends through C6-C1 transverse foramina and enters foramen magnum Internal thoracic Descends parasternally to anastomose with superior epigastric artery Thyrocervical trunk Gives rise to inferior thyroid, transverse cervical, and suprascapular arteries Part 2 Costocervical trunk Gives rise to deep cervical and superior intercostal arteries Part 3 Dorsal scapular Is inconstant; may also arise from transverse cervical artery Venous drainage Superficial veins External jugular vein EJV Drains most of scalp and side of face Formed at angle of mandible by union of retromandibular vein with posterior auricular vein Enters posterior triangle and pierces fascia of its roof Descends to terminate in subclavian vein Receives a.
Transverse cervical vein b. Suprascapular vein c. Muscles that are readily visible are trapezius, latissimus dorsi, and teres major.
The patient is placed in the left decubitus position, flexed in the fetal posture with the supracristal line vertical. The secondary curvatures are mainly a result of anterior-posterior differences in IV disc thickness. The cervical curvature is acquired when the infant begins to lift its head, and the lumbar curvature when the infant begins to walk.
Abnormal curvatures: Kyphosis is an increased thoracic curvature, commonly seen in the elderly "Dowager hump". It is usually caused by osteoporosis, resulting in anterior vertebral erosion or a compression fracture.
An excessive lumbar curvature is termed a lordosis and is seen in association with weak trunk muscles, pregnancy, and obesity. Scoliosis is an abnormal lateral curvature of the spine, accompanied by rotation of the vertebrae. Spondylolisthesis: The lumbosacral angle is created between the long axes of the lumbar vertebrae and the sacrum.
It is primarily because of the anterior thickness of the L5 body. As the line of body weight passes anterior to the SI joints, anterior displacement of L5 over S1 may occur spondylolisthesis , applying pressure to the spinal nerves of the cauda equina. They drain into the valveless vertebral venous plexus. The anesthetic solution spreads superiorly to act on spinal nerves S2-Co. The height to which the anesthetic ascends is affected by the amount of solution injected and the position of the patient.
Spinal block: Introduction of an anesthetic directly into the CSF in the subarachnoid space utilizing a lumbar puncture see above. Subsequent leakage of CSF may cause a headache in some individuals. Radiation to back of the thigh and into the leg sciatica or focal neurology suggests radiculopathy. Back strain: Stretching and microscopic tearing of muscle fibres or ligaments, often because of a sport-related injury.
The muscles subsequently go into spasm as a protective response causing pain and interfering with function. This is a common cause of low back pain. Frequently caused by impacts from the rear in motor vehicle accidents. May cause herniation of the IV disc and subsequent radiculopathy. The thoracic cage protects the contents of the thorax, whereas the muscles assist in breathing. It is important to identify and count ribs as they form key landmarks to the positions of the internal organs.
Midaxillary lines are perpendicular lines through the apex of the axilla on both sides Cephalic vein can be seen in some subjects lying in the deltopectoral groove between the deltoid and pectoralis major muscles. This is called a median sternotomy. The middle ribs are most commonly fractured, and multiple rib fractures can manifest as a "flail chest," where the injured region of the chest wall moves paradoxically, that is, in on inspiration and out on expiration.
The glands are rudimentary in males and immature females. Size and shape of the adult female breast varies; the size is determined by the amount of fat surrounding the glandular tissue. The base of the breast is fairly consistent extending from the lateral border of the sternum to the midaxillary line and from the 2nd to the 6th ribs. The majority of the breast overlies the deep pectoral fascia of the pectoralis major muscle, with the remainder overlying the fascia of the serratus anterior.
The breast is separated from the pectoralis major muscle by the retromammary space, a potential space filled with loose connective tissue. The breast is firmly attached to the overlying skin by condensation of connective tissue called the suspensory ligaments of Cooper , which help to support the lobules of the breast.
Asmall part of the mammary gland may extend toward the axilla, called the axillary tail of Spence. Structure of the Breast For descriptive purposes, the breast is divided into four quadrants: upper and lower lateral, and upper and lower medial. The most prominent feature of the breast is the nipple.
The nipple is surrounded by the areola, a circular pigmented area of skin. The areola is pink in Caucasians and brown in African and Asian people. The pigmentation of the areola increases during pregnancy. The areola contains sebaceous glands, following a pregnancy these secrete an oily substance to protect the mother's nipple from irritation during nursing.
The breast is composed of 15 to 20 lobules of glandular tissue, formed by the septa of the suspensory ligaments. The mammary glands are modified sweat glands that are formed from the development of milk-secreting alveoli, arranged in clusters. Each lobule is drained by a lactiferous duct Each lactiferous duct opens on the nipple.
The breast is also supplied by the branches of the thoracoacromial and lateral thoracic arteries from the axillary artery. Venous drainage parallels the arterial supply and is mainly to the axillary artery and internal thoracic vein.
Lymphatic Drainage of the Breast [Plate , Lymph Vessels and Nodes of Mammary Gland] Lymph from the nipple, areola, and lobules of the mammary glands drains to a subareolar lymphatic plexus.
From there, a system of interconnecting lymphatic channels drains lymph to various lymph nodes. The majority of the lymph, especially from the lateral quadrants of the breast, drains to the pectoral nodes, and from there to the axillary nodes.
The remaining amount of lymph, especially from the medial quadrants of the breast, drains into the parasternal lymph nodes along the internal thoracic vessels. Some lymph from the lower quadrants of the breast passes to the inferior phrenic nodes. It is important to note that lymph from the medial quadrants can cross to the opposite breast. Thus secondary metastases of breast carcinoma can spread to the opposite breast in this way.
The palpation should extend into the axilla to palpate the axillary tails. After palpation of one breast, the other should be palpated in the same way. Examine the skin of the breast for a change in texture or dimpling peau d'orange sign and the nipple for retraction, since these signs may indicate an underlying pathology. Pathology of the Breast Fibroadenoma: benign tumor, usually a solid and solitary mass that moves easily under the skin.
Often painless although sometimes tender on palpation. More common in young women but can occur at any age. Intraductal carcinoma or breast cancer: the commonest type of malignancy in women but can also occur in men. This malignancy presents as a palpable mass that is hard, immobile and sometimes painful.
Additional signs can include bloody or watery nipple discharge if the larger ducts are involved. Gynecomastia: enlargement of the breasts in males because of aging, drug treatment, and changes in the metabolism of sex hormones by the liver. External intercostal muscles: Have fibers that slope down and medially. Extend from the posterior tubercle of the rib to the junction of the rib and its costal cartilage anteriorly. Anteriorly, are replaced by external intercostal membranes that extend from the costochondral junctions to the sternum.
Internal intercostal muscles: Lie internal to the external intercostal muscles Their fibers lie at right angles to those of the external intercostal muscles and run inferiorly and laterally. Anteriorly extend to the lateral border of the sternum. Posteriorly extend only to the angles of the ribs; medial to the angles, are replaced by the internal intercostal membranes. Innermost intercostal muscles Lie deep to the internal intercostal muscles Are separated from the internal intercostals by the intercostal vessels and nerves Occupy the middle parts of the intercostal spaces Connect inner surfaces of adjacent ribs All intercostal muscles are supplied by intercostal nerves corresponding in number to their intercostal space.
Main action of the intercostals is to maintain the space between the ribs during inspiration and expiration. Other muscles of the rib cage Subcostal muscles-internal to the internal intercostals, cross from the angle of one rib to internal surface of the rib 1 to 2 spaces below.
Transversus thoracis-4 to 5 slips of muscle that attach to the xiphoid process and inferior sternum and pass superiorly and laterally to attach to the 2nd through 6th costal cartilages. Muscular branches supply the intercostal, levatores costarum, transversus thoracis, and serratus posterior muscles.
The lower five intercostal nerves supply the skin and muscles of the abdominal wall Contain general somatic afferent and efferent fibers, as well as general visceral efferent fibers from the sympathetic trunk via white and grey rami communicantes and general visceral afferent fibers.
Ribs 1 through 7 are vertebrocostal because they attach to the sternum via a costal cartilage. Ribs 8 through 10 are vertebrochondral because their cartilages are joined to the cartilage of the rib above and via that connection to the sternum. Ribs 11 and 12 are free or floating ribs, which do not connect even indirectly with the sternum but which have a costal cartilage on their tips. First rib is broad and sharply curved and has a tubercle of the attachment of scalene muscles. To avoid damage to the intercostal vein, artery, and nerve that run in the costal groove on the inferior surface of each rib, the needle is inserted well below the rib.
The needle also must be placed sufficiently above the rib below to avoid the collateral branches of intercostal nerve and vessels that run along the superior surface of each rib. They articulate with the C7 vertebra, but do not attach to the sternum. They may fuse with the first rib. If a cervical rib is present, however, it may compress the subclavian artery or inferior trunk of the brachial plexus and cause ischemic pain and numbness in the shoulder and upper limb. This condition is called thoracic outlet syndrome.
Bone Marrow Biopsy and Aspiration. Bone marrow aspiration and biopsy help diagnose many blood disorders and can be used to detect if cancer has spread to the bone marrow. Bone marrow biopsy: The removal of bone and marrow for examination under the microscope. The sternum is a site of red marrow, even in adulthood, and is a good site for a bone marrow biopsy.
Another common site is the posterior iliac crest. Abiopsy is usually conducted before performing a bone marrow aspiration. Bone marrow aspiration: The removal of a small amount of bone marrow fluid through a needle inserted into the bone. Fluid is examined to determine if there are any problems with the blood cells made in the bone marrow Mnemonics Memory Aids Vertical order of the contents of the neurovascular bundle in the costal groove on the lower border of each rib: VAN Vein, Artery, Nerve.
The pleural cavity contains a thin layer of serous pleural fluid, which lubricates and allows the pleurae to move smoothly over each other during respiration. Surface tension keeps the lung surface in contact with the thoracic wall. The lung expands and fills with air when the thoracic cavity expands. The sternal line of pleural reflection is the sharp line along which the costal pleura becomes the mediastinal pleura The costal line of pleural reflection is the sharp line along which the costal pleura becomes the diaphragmatic pleura The vertebral line of pleural reflection is a smooth reflection of the costal pleura onto the vertebrae posteriorly.
The lines of pleural reflection on the left side can be remembered as The line of pleural reflection on the left descends in the midline of the sternum to the 4th costal cartilage, where it deviates to the left margin of the sternum at the 6th costal cartilage to accommodate the pericardium and the heart cardiac notch.
This line then deviates to cross the 8th rib at the midclavicular line. It crosses the 10th rib at the midaxillary line It then crosses the 12th rib at approximately the neck. On the right side, the line of pleural reflection descends at the midline of the sternum to the xiphoid process, and then deviates The lungs do not fully occupy the pleural cavities during expiration There are peripheral areas where the diaphragmatic and costal pleura come in contact and these are called the costodiaphragmatic recesses.
There are areas posterior to the sternum where the costal and mediastinal pleura come in contact with each other, and these are called costomediastinal recesses. The costomediastinal recess is larger on the left, because of the cardiac notch. During expiration, the lower limit of the lungs is two costal spaces above the line of pleural reflection: the sixth rib at the midclavicular line, the 8th rib at the midaxillary line, and the 10th rib at the neck.
Thus the costodiaphragmatic recess is approximately two costal spaces deep. The horizontal fissure runs from the oblique fissure at the midaxillary line along the 4th rib to its costal cartilage anteriorly. The anterior margin of the left lung has an indentation-the cardiac notch, which often creates a thin process in the upper lobe called the lingula. Each lung has three surfaces: Costal Mediastinal Diaphragmatic Each lung is connected to the mediastinum by the root of the lung.
Lung root contains: Main stem or lobar bronchi Pulmonary vessels and bronchi. Bronchial vessels, lymphatics, and autonomic nerves.
The lung root is surrounded by a pleural sleeve, from which extends the pulmonary ligament inferiorly. The carina is the keel-like ridge between the two openings of the main stem bronchi. The right main stem bronchus divides into upper and lower lobar bronchi before reaching the substance of the right lung. The main bronchi branch to form the bronchial tree. There are three lobar bronchi on the right: upper, middle, and lower There are two lobar bronchi on the left: upper and lower Each lobar bronchus branches into segmental bronchi that supply a bronchopulmonary segment.
Each pulmonary artery gives rise to lobar and segmental arteries. Intrasegmental veins drain to intersegmental veins in the pulmonary septa, which run a separate course from the pulmonary and segmental arteries and which drain to two pulmonary veins for each lung. Pulmonary veins carry oxygenated blood to the left atrium of the heart. Bronchial arteries from the thoracic aorta carry oxygenated blood to the tissue of the lungs, traveling along the posterior surface of the bronchi.
The left bronchial arteries come from the thoracic aorta; the single right bronchial artery may also arise from the superior posterior intercostal or a left superior bronchial artery. The bronchial arteries anastomose with branches of the pulmonary arteries. Pulmonary veins drain the blood to the lungs supplied by the bronchial veins and empty into the azygos and accessory hemiazygos veins.
The lungs have a rich, freely connecting network of lymphatic vessels. Lymph from the lungs drains to Pulmonary lymph nodes along the lobar bronchi Bronchopulmonary lymph nodes along the main stem bronchi Superior and inferior tracheobronchial lymph nodes superior and inferior to the bifurcation of the trachea Innervation of the lungs Innervation is via the pulmonary plexuses located anterior and posterior to the lung roots.
The plexuses contain postganglionic sympathetic fibers from the sympathetic trunks that innervate the smooth muscle of the bronchial tree, pulmonary vessels, and glands of the bronchial tree.
Sympathetic fibers are bronchodilators, vasoconstrictors, and inhibit glandular secretion. The plexuses contain preganglionic parasympathetic fibers from the vagus nerve CN X , small parasympathetic ganglia, and postganglionic parasympathetic nerves that innervate the smooth muscle of the bronchial tree, pulmonary vessels, and glands of the bronchial tree.
Parasympathetic fibers are bronchoconstrictors, vasodilators, and secretomotor to the glands. Pneumonia: a bacterial or viral infection of the lung that can lead to widespread systemic infection and lung collapse.
Pneumonia is frequently confined to a single lobe of one lung and is called lobar pneumonia. It can be clearly seen circumscribed to one lobe in a chest radiograph. The entry of air into a pleural cavity because of a penetrating wound or a fractured rib is called a pneumothorax and results in partial or total collapse of the lung. The escape of fluid into the pleural cavity pleural effusion is called hydrothorax; if the fluid is blood, the condition is known as a hemothorax, and if it is chyle from the thoracic duct, it is called a chylothorax.
Inflammation of the pleurae is called pleuritis or pleurisy; resulting friction between the two pleurae pleural rub is very painful and can be heard with a stethoscope. The inflamed pleurae may adhere to each other pleural adhesion Squamous cell or oat cell carcinoma is a common cancer of the lung, usually caused by smoking, that may be indicated by a persistent cough or spitting of blood hemoptysis.
The fibrous outer layer of the pericardium the fibrous pericardium consists of dense connective tissue. The fibrous pericardium is attached to the central tendon of the diaphragm by the pericardiacophrenic ligament. It blends with the tunica adventitia of the vessels entering and leaving the heart.
It has ligamentous attachments to the sternum It is thus affected by movements of the heart, the great vessels, the sternum, and the diaphragm. It protects the heart against overfilling because it is fibrous and unyielding The inner layer of the pericardium is a serous membrane that lines the fibrous pericardium: the serous pericardium, also called the parietal pericardium.
The serous pericardium is a mesothelial layer that reflects onto the roots of the great vessels and is continuous over the external surface of the heart, where it is called the epicardium or visceral pericardium. Between the serous pericardium parietal pericardium and the epicardium visceral pericardium is a potential space: the pericardial cavity. The pericardial cavity normally contains a thin film of fluid that allows the two layers to move over each other without friction or rubbing.
There are two sinuses within the pericardial cavity: the transverse sinus and the oblique sinus. The transverse pericardial sinus runs transversely in the pericardial sac between the origins of the great vessels: posterior to the ascending aorta and pulmonary trunk and anterior to the superior vena cava. The oblique pericardial sinus is a wide recess in the posterior wall of the pericardial sac bounded laterally by the entrances of the pulmonary veins and inferiorly by the orifice of the inferior vena cava.
Blood supply to the layers of the pericardium is mainly from the pericardiacophrenic vessels, from the internal thoracic arteries and veins. The nerve supply to the pericardium is from the phrenic nerves, primarily sensory fibers for pain, and the sympathetic trunks vasomotor. The right side of the heart receives poorly oxygenated blood from the superior and inferior vena cava and pumps it to the lungs for oxygenation.
The left side of the heart receives oxygenated blood from the lungs via the pulmonary veins and pumps it to the body via the aorta and its branches. The heart consists of four chambers: the right and left atria and the right and left ventricles. The functions of the fibrous skeleton are: Maintains the patency of the atrioventricular valves Provides a fixed site for the attachment of the leaflets and cusps of the valves Provides a fixed site for the attachments of the cardiac muscle fibers Insulates the atria from the ventricles so that they can contract independently The cardiac cycle consists of Relaxation of the ventricles diastole followed by Contraction of the ventricles diastole Heart sounds heard with a stethoscope: "lub"-blood from the atria fills the ventricles "dub"-ventricles contract and push blood out of the heart Orientation of the Heart: Border and Surfaces [Plate , Heart: Base and Diaphragmatic Surfaces] The heart lies obliquely between the 3rd and the 5th ribs, mainly on the left side of the midline of the thorax, but with roughly a third of it slightly to the right.
The base of the heart is its posterior surface, which is the left atrium. The apex of the heart is formed from the most inferior and lateral part of the left ventricle and lies beneath the left 5th intercostal space at approximately the midclavicular line. The anterior wall is ridged with the pectinate muscles. The smooth and rough parts of the right atrium are separated internally by a smooth ridge, the crista terminalis, which presents externally as shallow groove, the sulcus terminalis.
The superior vena cava opens into the superior aspect of the right atrium. The inferior vena cava opens into the inferior part, in a direct line with the superior vena cava. An interatrial septum separates the right and left atria. An oval depression in the interatrial septum, the fossa ovalis, represents the fetal foramen ovale and its valve. Aright atrioventricular AV orifice opens into the right ventricle Right ventricle The right ventricle is situated in front and to the left of the right AV orifice.
The interior has prominent muscular ridges, the trabeculae carnea. The tricuspid valve or right AV valve usually consists of three leaflets. The bases of the leaflets or cusps are attached to the fibrous ring around the orifice. The free edge of each leaflet is attached to two of the three papillary muscles by tendinous cords chordae tendinea.
The papillary muscles are three in number: septal, anterior and posterior. These muscles contract before the ventricle itself contracts, tightening the chordae tendinea and drawing the cusps of the valve together to prevent backflow of blood into the right atrium. The septomarginal trabecula, or moderator band, is a free band of muscle extending from the interventricular septum to the anterior wall of the ventricle, and it contains Purkinje fibers from the right bundle branch see conducting system.
The outflow tract of the ventricle is separated from the inflow tract by a smooth crest, the supraventricular crest. The outflow tract, or conus arteriosus, is smooth walled and leads to the pulmonary trunk and the valve that guards its orifice, the pulmonary valve.
It has a smooth walled portion from the developmental incorporation of a portion of the pulmonary veins and an auricular appendage which is ridged with pectinate muscles and which was the primitive left atrium. Four pulmonary veins empty into the left atrium. The interatrial septum is nearly transverse, sloping posteriorly and to the right The left atrioventricular orifice leads to the left ventricle.
Left Ventricle page page The left ventricle is nearly twice as thick as the right ventricle, since it performs more work to circulate blood to the body. It has a conical cavity, the apex of which is the apex of the heart. Its walls are lined with trabeculae carnea, which are more numerous and not as massive as the ones in the right ventricle. It contains only two papillary muscles, anterior and posterior, which both attach to the two leaflets of the left atrioventricular, or mitral, valve via chordae tendinea.
These muscles contract before the ventricle itself contracts, tightening the chordae tendinea and drawing the cusps of the valve together to prevent backflow of blood into the left atrium.
The aortic orifice is located posteriorly and superiorly and, like the pulmonary orifice, is surrounded by a fibrous ring to which the three cusps of the aortic valve are attached.
The aortic valve has three cusps, which open like pockets to catch blood that backflows from the aorta during ventricular diastole. There are dilations in the wall of the aorta beneath each cusp: the aortic sinuses. The right coronary artery originates in the right aortic sinus, while the left coronary artery originates in the left aortic sinus.
They arise from the corresponding aortic sinuses, just distal to the origin of the aortic valve. The left coronary artery passes between the left auricle and the pulmonary trunk.
Its main branches are Acircumflex branch, which reaches the posterior surface of the heart by traveling in the atrioventricular groove around the left side of the heart In slightly less than half of all people, a sinoatrial SA nodal branch from the circumflex branch will supply the SAnode.
An anterior interventricular branch left anterior descending artery or LAD , which descends in the anterior interventricular groove to the apex of the heart and then anastomoses with the posterior interventricular artery.
The right coronary artery runs in the atrioventricular groove to the right and around to the posterior surface of the heart. It gives rise to The SAnodal branch near its origin in most people Aright marginal branch to the right margin of the heart An AV nodal branch to the atrioventricular node, as the junction of the septa and four chambers of the heart on the posterior side of the heart Aposterior interventricular branch that runs in the posterior interventricular groove.
It consists of The sinoatrial node SAnode , located at the superior end of the sulcus terminalis of the right atrium, near the entrance of the superior vena cava The SAnode is the so-called pacemaker of the heart, from which impulses for contraction are initiated and spread through the musculature of both atria. Fibers from the cardiac plexus supply the SAnode. Sympathetic innervation accelerates the rate and force of contraction of heart muscle.
Parasympathetic stimulation slows down the rate and force of contraction of heart muscle. Signal from the SAnode is propagated by the cardiac muscle to the AV node. The AV node is located near the inferior end of the interatrial septum posteriorly, near the septal cusp of the tricuspid valve. The AV bundle carries the signal from the AV node through the fibrous skeleton of the heart and the membranous interventricular septum. It divides into right and left bundles that pass on either side of the muscular interventricular septum.
The fibers of the right and left bundles Purkinje fibers spread into the walls and papillary muscles of the ventricles. Purkinje fibers from the right bundle innervate the anterior papillary muscle of the right ventricle via the septomarginal trabecula or moderator band, to coordinate the timing of the contraction of the papillary muscles. Heart Sounds Clinicians need to listen to valve sounds. Blood carries sound in the direction of its flow, so valve sounds are best heard auscultated directly superficial to their location or at the end of a line of blood flow through the valve.
Similarly, stab wounds to the heart can result in the leakage of blood into the pericardial cavity. As excess blood or fluid accumulates in the pericardial cavity, the heart becomes increasingly inhibited from expanding as it beats, and blood flow to the ventricles is impeded. This situation is called cardiac tamponade and is a potentially lethal condition.
Symptoms include distension of neck veins and a collapsing pulse, i. Pericardiocentesis Pericardiocentesis or drainage of fluid from the pericardial cavity is necessary to relieve cardiac tamponade. Awide bore needle is inserted into the 5th or 6th intercostal space adjacent to the sternum but not too close because of the presence of the internal thoracic vessels.
This approach can be made because of the cardiac notch in the left lung and left parietal pleura, leaving the pericardial sac exposed. Aneedle can also be inserted into the infrasternal angle, again being careful of the internal thoracic artery and its branches, and passed superiorly and posteriorly to reach the pericardial sac.
Cardiac Referred Pain While the heart is generally insensitive to various stimuli, ischemia lack of oxygen and the resulting accumulation of metabolic products registers as pain, typically in the left pectoral and substernal regions and over the medial aspect of the left shoulder and upper limb.
The axons of visceral afferent fibers from the heart typically enter spinal cord segments from T1 through T4 or 5 on the left side. General sensory fibers from these areas also enter the same spinal cord segments Cardiac Bypass Graft CABG In this surgery, the patient has a blood vessel grafted into the coronary circulation to bypass an occlusion in one of the coronary arteries or its branches. In the past, the saphenous vein was commonly used in the bypass graft, because it is easily obtained from the lower limb and has lengthy sections without valves or branches.
The internal thoracic artery is more frequently used to shunt blood from the aorta to branches of the coronary arteries beyond the occlusion. This restores normal blood flow to the part of the heart distal to the blockage. It can be a result of any one of several developmental anomalies, such as failure of the embryonic endocardial cushions, which form part of the septum, to fuse.
Aleft to right flow of blood occurs with this defect because of the strength of contraction of the left ventricle. This increases the blood flow through the pulmonary trunk to the lungs and results in pulmonary hypertension increased blood pressure and an enlarged heart. This condition is potentially fatal if not corrected. Pathologies of the Aorta Aneurysms of the ascending aorta An aortic aneurysm is an enlargement of a weakened area of the aorta, in this case in the distal part of the ascending aorta.
Ascending aortic aneurysms frequently cause dilation and leakage of the aortic valve, resulting in shortness of breath or even heart failure. Aortic dissection is a tearing of the internal wall of the aorta, with subsequent bleeding into the wall, as the result of an aneurysm, atherosclerosis, or high blood pressure.
Coarctation of aorta is a birth defect in which the aorta is narrowed somewhere along its length, most commonly just past the point where the subclavian artery arises. This results in low blood pressure in branches of the aorta distal to the narrowing and high blood pressure in branches between the narrowing and the heart. People with this condition often have high blood pressure in the upper body and arms or one arm and low blood pressure in the lower body and legs.
The intercostal arteries can become enlarged, since the anastomoses of the anterior intercostals from the internal thoracic artery with the posterior intercostals can circumvent the narrowing. Aortic coarctation is more common in some genetic conditions such as Turner syndrome but also can be associated with congenital abranditemities of the aortic valve such as a bicuspid aortic valve.
Valvular Insufficiencies The mitral valve is the heart valve most frequently affected by disease. It can be caused by endocarditis, myocarditis, rheumatic heart disease, or lupus erythematosus, or can result from a developmental abranditemity. The diseased mitral valve allows reversal of blood flow from the left ventricle to the left atrium mitral regurgitation. It is characterized by a high pitched murmur, loudest over the apex of the heart. Narrowing of the pulmonary valve stenosis is caused by fusion of the valve cusps.
It can result from a developmental abranditemity or diseases such as rheumatic fever or endocarditis. Stretches from the thoracic inlet to the diaphragm and from the sternum to the bodies of the thoracic vertebrae posteriorly. Its contents include the heart, trachea, esophagus, great vessels of the heart, lymph nodes, nerves, and fat. Superior mediastinum contains the superior vena cava arch of the aorta and its branches trachea phrenic nerves thoracic duct esophagus vagus nerves left recurrent laryngeal nerve thymus Inferior mediastinum is subdivided into anterior mediastinum middle mediastinum posterior mediastinum The anterior mediastinum contains fat and the remnants of the thymus gland The middle mediastinum contains the heart surrounded by the pericardium and the roots of the great vessels.
Thymus gland plays a central role in the development of the immune system lies posterior to the manubrium receives blood from the internal thoracic and anterior intercostal arteries is gradually replace by adipose tissue after puberty b. Heart and pericardial sac Section Thorax-Heart c. Superior vena cava Formed by the union of two brachiocephalic veins Returns blood to the heart from all structures above the diaphragm except the heart and lungs Descends vertically and terminates in the right atrium Lies to the right of the ascending aorta and to the left of the right phrenic nerve Receives azygous veins before piercing fibrous pericardium d.
Brachiocephalic veins Are formed in the root of the neck posterior to the sternoclavicular joints by union of the internal jugular and subclavian veins. Right brachiocephalic vein receives lymph from the right lymph duct. Left brachiocephalic vein is twice as long as the right runs obliquely down and behind the manubrium crosses the roots of the three major branches of the aorta receives lymph from the thoracic duct e.
Aorta Ascending begins at the aortic orifice ascends to the 2nd right sternocostal joint Arch Begins at the 2nd right sternocostal joint and arches superiorly and to the left Anterior to the right pulmonary artery and bifurcation of the trachea Passes over the root of the right lung Ends at the body of the T4 vertebra Descending thoracic begins at the body of T4 vertebra descends on the left side of the bodies of T vertebrae, posterior to the root of the left lung and the pericardium enters the abdomen through the aortic hiatus at the T12 vertebral body has a number of branches: bronchial pericardial twigs superior phrenic 1 pair esophageal 2 posterior intercostal 9 pairs subcostal 1 pair f.
Vascular supply arterial: esophageal branches of the thoracic aorta venous: azygos, hemiazygos and accessory azygos veins h. Azygos venous system Drains blood from the back and thoracoabdominal walls Is highly variable Is composed of an unpaired azygos vein and its main tributary, the hemiazygos vein. Phrenic nerves Supply motor and sensory fibers to the diaphragm Enter the superior mediastinum between the subclavian artery and brachiocephalic vein on either side Pass anterior to the roots of the lungs, unlike the vagus nerve The right phrenic nerve descends on the right side of the inferior vena cava to the diaphragm The left phrenic nerve crosses the arch of the aorta descends anterior to the root of the left lung and along the pericardium over the left atrium and ventricle pierces the diaphragm to the left of the pericardium 1.
Surgery, injury, or disease affecting the contents of superior mediastinum can damage either or both recurrent laryngeal nerves, reducing the voice to a hoarse whisper. The left recurrent laryngeal nerve passes beneath the arch of the aorta and ascends to the neck between the trachea and the esophagus. Bronchogenic or esophageal carcinoma or an aneurysm of the arch of the aorta can thus affect this nerve. Chylothorax Surgical procedures involving the posterior mediastinum can injure the thoracic duct, which is hard to identify because it has a thin wall and is usually colorless.
Injury to the thoracic duct can lead to leakage of lymph into the thoracic cavity at a volume of up to mL per hour. Lymph is called chyle when it is carrying chylomicrons fat droplets from the digestion of food in the gastrointestinal system. If lymph from the thoracic duct enters the pleural cavity, the resulting condition is called a chylothorax and may require removal by thoracocentesis. Mnemonics Memory Aids To remember the spinal nerve contributions to the phrenic nerve: C3,4,5 keeps the diaphragm alive T8-Site at which inferior vena cava pierces the diaphragm TSite at which esophagus pierces the diaphragm TSite at which aorta pierces the diaphragm Memory Aids SAT for major contents of the superior mediastinum : Superior vena cava, Arch of aorta, and Trachea Turkeys Blow Eggs: Trachea lies Behind the Esophagus page page Memory Aids Relationship of Thoracic Duct to Esophagus and Azygos Vein "The duck lies between two gooses.
Is the largest cavity in the body and is continuous with the pelvic cavity. Lined with parietal peritoneum, a serous membrane Bounded superiorly by the diaphragm Has a concave dome Spleen, liver, part of the stomach, and part of the kidneys lies under the dome and are protected by the lower ribs and costal cartilages.
Lower extent lies in the greater pelvis Between the ala or wings of the ilia Ileum, cecum, and sigmoid colon thus partly protected Anterior and lateral walls composed of muscle Viscera in these areas are more likely to be damaged by blunt force and penetrating injuries.
Posterior wall comprised of vertebral column, the lower ribs, and associated muscles Protect the abdominal contents. All the rest of the organs are peritoneal Lie within the peritoneal cavity Covered by a layer of visceral peritoneum Visceral peritoneum is continuous with the parietal peritoneum lining the cavity via a mesentery. These planes create nine abdominal regions: Right and left hypochondriac regions, superiorly on either side Right and left lumbar flank regions, centrally on either side Right and left inguinal groin regions, inferiorly on either side Epigastric region superiorly and centrally Umbilical region, with the umbilicus as its center Hypogastric or suprapubic region, inferiorly and centrally Descriptive quadrants and regions are essential in clinical practice Each area represents certain visceral structures Allow correlation of pain and referred pain from these areas to specific organs.
Appendicitis: inflammation of the appendix. Pain first presents in the epigastric region, moves to the umbilical region and then localizes in the right lower quadrant. Rupture of the appendix leads to peritonitis inflammation of the peritoneum. This presents with severe pain, fever, and abdominal rigidity. Muscle-splitting incision of McBurney : used to access the appendix. Each muscle layer is split in the direction of the fiber orientation.
The incision must not go too far laterally or the ascending branch of the deep circumflex iliac artery may be severed. Clinical Points Grey-Turner's sign Local right flank redness or bruising ecchymosis Indicates a retroperitoneal hemorrhage Usually takes 24 to 48 hours to appear Can be predictive of severe hemorrhagic pancreatitis, abdominal injury, or metastatic cancer page page Clinical Points Cullen's sign Discoloration ecchymosis around the umbilicus Aresult of peritoneal hemorrhage Mnemonics Memory Aids Causes for abdominal expansion protuberance : Remember the five Fs: Fat Feces Fetus Flatus Fluid.
Transversalis fascia endoabdominal fascia Athin membranous sheet lining most of the abdominal wall Lies deep to the transversus muscles and the linea alba Endoabdominal fat separates the transversalis fascia from the parietal peritoneum Muscles Functions Protect the viscera Help maintain posture Can compress the abdominal contents, thus raising intra-abdominal pressure, such as in sneezing, coughing, defecating, micturating, lifting, and childbirth Four paired muscles make up the anterolateral abdominal wall Three flat muscles Asingle vertical muscle.
Three flat muscles include The external abdominal oblique a. Largest and most superficial b. Fibers run inferiorly and medially and end in aponeurosis that contributes to the rectus sheath. Inferior border of its aponeurosis forms the inguinal ligament, where it thickens and folds back on itself d. Innervated segmentally by T6-T12 spinal nerves and subcostal nerve The internal abdominal oblique a. Athin muscular layer b. Fibers run inferiorly and laterally and end in an aponeurosis that contributes to the rectus sheath c.
Innervated segmentally by the ventral rami of T6-T12 spinal nerves The transversus abdominis a. Innermost of the three flat muscles b. Fibers run transversely and medially and end in an aponeurosis that contributes to the rectus sheath.
Innervated segmentally by the ventral rami of T6-T12 spinal nerves Linea alba a. We hope that you people find our blog beneficial! Now before that we move on to sharing the free PDF download of Atlas of Human Anatomy PDF with you, here are a few important details regarding this book which you might be interested. The only anatomy atlas illustrated by physicians, Atlas of Human Anatomy PDF brings you world-renowned, exquisitely clear views of the human body with a clinical perspective.
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