David A. Tate, MD

• Associate Professor of Medicine
• Division of Cardiology
• University of North Carolina School of Medicine
• Chapel Hill, North Carolina

Lymph from all these nodes ultimately reaches the coeliac nodes (around coeliac trunk) muscle relaxant migraine purchase 250mg ponstel visa. S:Superiorpart;D:Descendingpart; H:Horizontalpart;A:Ascendingpart 542 want to know more Chapter 27 Oesophagus knee spasms causes purchase ponstel 250mg visa, Stomach and Intestines Ascending (Fourth) Part Anteriorly a muscle relaxant football commercial order cheap ponstel on line. The mucous membrane of the jejunum is marked by the presence of numerous spasms near kidney generic 250 mg ponstel otc, large muscle relaxant abuse best order ponstel, transverse muscle relaxer zoloft order discount ponstel on-line, folds. Thesearethecaecum,theascending colon,thetransverse colon,thedescending colon,thesigmoid (or pelvic)colon,therectum andtheanal canal. The veins from the colon drain through the superior and inferior mesenteric veins. The preganglionic neurons concerned are located in segments S2, S3 and S4 of the spinal cord. It is included amongst the accessory organs of the alimentary system because it produces a secretion, the bile, which is poured into the duodenum (through the bile duct) and assists in the digestive process. All the blood circulating through the capillary bed of the abdominal part of the alimentary canal (excepting the lower part of the anal canal) reaches the liver through the portal vein and its tributaries. In this way, all substances absorbed into the blood from the stomach and intestines are filtered through the liver, where some of them are stored and some toxic substances may be destroyed. Numerous other functions essential to the well being of the individual are performed in the liver that is, therefore, regarded as one of the vital organs. It lies mainly in the right hypochondrium and in the epigastrium, but part of it extends into the left hypochondrium and part of it into the right lateral region. To the right of the midline, the upper border follows the upward convexity of the right dome of the diaphragm reaching to a level just below the right nipple. To the left of the midline, the upper border follows the curve of the medial part of the left dome of the diaphragm, and ends a little below and medial to the left nipple. The right border runs vertically, with an outward convexity and ends at the level of the tip of the tenth costal cartilage. A liver extending below the level of the lateral part of the right costal margin is considered to be enlarged. Above it has a convex diaphragmatic surface, and below it has an inferior or visceral surface. These parts are sometimes referred to as anterior, superior and posterior surfaces but there are no features that demarcate them from one another. Before proceeding to study the features to be seen on individual surfaces of the liver, it is necessary to briefly consider the basic peritoneal relationships of the organ. At an early stage in development, the stomach has a ventral mesogastrium that passes from its ventral border (future lesser curvature) to the developing diaphragm and anterior abdominal wall (28. After the formation of the liver the peritoneum of the ventral mesogastrium passes from the stomach to the liver, covers the greater part of the liver, and is then reflected from the liver to the diaphragm and anterior abdominal wall (28. The part of the ventral mesogastrium between the stomach and the liver becomes the lesser omentum. The lesser omentum gains attachment (partly) to an area on the visceral surface of the liver called the porta hepatis (28. Here, the two layers of the peritoneum forming it separate to cover the greater part of the liver surface. The peritoneum from the surface of the liver is reflected on to the diaphragm (and anterior abdominal wall) in the form of a number of ligaments that are identified in the paragraphs that follow. In both these figures, we see the anterior and superior parts of the diaphragmatic surface. The anterior part of the diaphragmatic surface is lined by peritoneum except along a line near the median plane. Along this line, the peritoneum is reflected off from the liver to the diaphragm, and to the upper part of the anterior abdominal wall as the falciform ligament. The line of attachment of the falciform ligament has traditionally been used to divide the liver into a larger right lobe and a much smaller left lobe. However, most authorities agree that the division of the liver into right and left lobes should be based on the areas drained by the right and left hepatic ducts. Apart from the falciform ligament, peritoneum from the superior part of the diaphragmatic surface is reflected on to the diaphragm in the form of: a. The posterior aspect of the liver is marked by a deep notch for the vertebral column (28. The upper part of this figure shows the posterior part (and adjoining superior part) of the diaphragmatic surface. These are the attachments of the left triangular ligament, the upper layer of the coronary ligament, the right triangular ligament, and the groove for the inferior vena cava. A considerable area on the posterior part of the diaphragmatic surface of the liver is not covered by peritoneum and is, therefore, called the bare area. It includes the groove for the inferior vena cava and a large triangular area on the right of it. The triangle is bounded above by the attachment of the superior layer of the coronary ligament and below by the attachment of the inferior layer of the same ligament. These two layers meet towards the right side to form the right triangular ligament. To the left of the groove for the inferior vena cava there is a circumscribed part of the posterior surface that is called the caudate lobe. The caudate lobe is bounded on its left side by a deep groove called the fissure for the ligamentum venosum. Inferiorly, the caudate lobe is separated from the visceral surface by the porta hepatis (which is in the form of a transverse groove). The hepatic artery and portal vein enter the liver here, while the right and left hepatic ducts leave it. The porta hepatis and the fissure for the ligamentum venosum give attachment to the two layers of the lesser omentum. The structures entering or leaving the liver at the porta hepatis (portal vein, hepatic artery, bile duct) are enclosed between the two layers of peritoneum forming the lesser omentum. A narrow strip of liver tissue intervenes between the posterior aspect of the porta hepatis and the groove for the inferior vena cava. It connects the caudate lobe (on the left) to the visceral surface of the right lobe (on the right). The most conspicuous feature on the visceral surface of the liver is the gall bladder. It lies in a depression on the liver surface called the fossa for the gall bladder. This fossa is not usually exposed to view as the gall gladder is fixed to the liver by peritoneum as shown in 28. Starting near the right end of the porta hepatis the gall bladder runs downwards and forwards across the visceral surface of the liver. Another conspicuous feature to be seen on the visceral surface is the fissure for the ligamentum teres. This fissure runs from the left end of the porta hepatis to the inferior margin 28. The part of the visceral surface between the fissure for the ligamentum teres and the fossa for the gall bladder is called the quadrate lobe (because of its quadrangular shape). It is bounded posteriorly and above by the porta hepatis, and anteriorly and below by the inferior margin of the liver. In relation to the diaphragmatic surface, it has been mentioned that the attachment of the falciform ligament is used to divide the liver into right and left lobes. On the visceral surface, the line of division runs along the fissure for the ligamentum venosum and the fissure for the ligamentum teres. The visceral surface of the liver comes into contact with several viscera that are as follows (28. A strip along the inferior margin of the liver comes in contact with the transverse colon. The oesophagus comes in contact with a depression to the left of the upper end of the fissure for the ligamentum venosum. The part of the visceral surface to the left of the fissure for the ligamentum venosum and the ligamentum teres comes in contact with the stomach, and with the lesser omentum. The area for the stomach is in the form of a shallow depression called the gastric impression. The first part of the duodenum crosses the upper part of the gall bladder, while the superior duodenal flexure comes into contact with an area immediately to the right of the upper part of the gall bladder. To the right of the area for the superior duodenal flexure, and above the area for the transverse colon, the visceral surface bears a large impression for the right kidney. The liver comes in contact with the right suprarenal gland above and medial to the impression for the kidney. The suprarenal produces a depression on the bare area immediately to the right of the lower part of the inferior vena cava. The liver has been traditionally divided into right and left lobes using certain surface features. On the anterior and superior parts of the diaphragmatic surface, the line of demarcation is the attachment of the falciform ligament. On the posterior part of the diaphragmatic surface, the line of demarcation is the fissure for the ligamentum venosum. On the visceral surface, the demarcation is by the fissure for the ligamentum teres. According to this plan of division, the caudate and quadrate lobes form part of the right lobe. The liver is drained by two hepatic ducts, right and left which join to form the common hepatic duct. It is rational to regard the territory drained by the right hepatic duct as the true right lobe and that drained by the left hepatic duct as the true left lobe. On the visceral surface, the line of demarcation between these territories lies roughly along the fossa for the gall bladder. On the posterior part of the liver, the line lies along the groove for the inferior vena cava. On the anterosuperior part of the diaphragmatic surface, the line is not marked by any surface feature. It can be represented roughly by a line joining the fundus of the gall bladder and the upper end of the inferior vena cava (red lines in 28. Note that the caudate and quadrate lobes lie in the territory drained by the left hepatic duct. Each lobe, thus defined is divisible into a number of segments based on the branching pattern of the hepatic ducts within the liver. On the visceral surface it corresponds to the quadrate lobe, and the caudate lobe. The medial and lateral parts of the left lobe are each divided into superior and inferior segments. It is important to remember, however, that there are no surface features to outline the segments, and that there is considerable individual variation in the size and relationship of individual segments to the surface of the liver. The subdivision is, therefore, not very useful to a surgeon wanting to remove a part of the liver. Further Consideration of Peritoneal Folds Attached to the Liver the Lesser Omentum 1. The lesser omentum consists of two layers of peritoneum that are continuous with the peritoneum lining the anterior and posterior surfaces of the stomach (28. It is attached by its lower edge to the lesser curvature of the stomach and to the proximal portion of the first part of the duodenum. This attachment is to the fissure for the ligamentum venosum and to the lips of the porta hepatis (28. Extending between the duodenum and the right extremity of the porta hepatis the lesser omentum has a free edge formed by continuity of the anterior and posterior layers. The structures that lie between the two layers of the omentum near its free edge are: i. Along the lesser curvature of the stomach, the right and left gastric arteries and veins lie within the omentum. The right margin of the omentum forms the anterior boundary of the aditus to the lesser sac. The anterior layer of peritoneum forming the omentum can be traced down to the front of the pylorus and the commencement of the duodenum. The caudate lobe is bounded on the left side by the fissure for the ligamentum venosum. The lesser omentum extends to the bottom of the fissure where its layers are reflected on to the walls of the fissure. In this way, a narrow recess of the cavity of the lesser sac comes to lie behind the caudate lobe. The peritoneum lining the posterior surface of the caudate lobe is reflected on to the diaphragm along the upper border of the lobe thus forming the upper limit of the superior recess of the lesser sac. The falciform ligament is attached on the anterior and superior parts of the diaphragmatic surface of the liver. Its lower part is attached anteriorly to the anterior abdominal wall, the attachment extending up to the level of the umbilicus and posteriorly it has a free edge formed by continuity of the two layers of peritoneum (right and left) that form it. The upper part of the ligament is a short fold passing from the diaphragm to the liver. The ligamentum teres is enclosed within the falciform ligament (near its free edge). It passes from the umbilicus to the inferior border of the liver within the ligament. The superior and inferior layers form the upper and lower boundaries of the bare area of the liver. Towards the right side the superior and inferior layers meet at an acute angle to form the right triangular ligament.

The anterior and posterior compartments are separated from each other by the interosseous membrane (that stretches between the interosseous borders of the tibia and fibula) muscle relaxant definition purchase ponstel once a day. The posterior compartment of the leg is divided into superficial infantile spasms 4 year old order ponstel visa, middle and deep parts by superficial and deep transverse septa spasms in 6 month old baby order cheap ponstel. In the living person the tendon of the tibialis anterior can be felt just lateral to the anterior border of the tibia spasms translation order line ponstel. CliniCal Correlation Excessive strain on the tibialis anterior muscle (in atheletes) produces small tears near its attachments spasms in your stomach cheap ponstel 250mg without prescription. Helps to maintain arches of foot Extensor hallucis longus Base of distal phalanx of 1 spasms in neck order ponstel overnight delivery. Extends phalanges of Deep peroneal nerve (L5, S1) great toe (dorsal aspect) great toe 2. Uppermost part from digit) divides into three lateral condyle of tibia slips, one intermediate and two collateral 3. The collateral slips reunite and are inserted into the base of the distal phalanx Contd. Muscle Extensor digitorum brevis 265 Origin Insertion Action Nerve supply Anterior part of cal- 1. Helps extensor digito- Deep peroneal nerve caneus (on superior and dons (for first, second, rum longus in exten- (S1, 2) lateral aspect) third and fourth digits) sion of 2nd, 3rd, and 4th toes 2. Extension of proximal responding tendon of phalanx of great toe extensor digitorum longus 3. The tendon for the first digit is inserted into the dorsal surface of the base of the proximal phalanx of the great toe 1. Eversion of foot of base) Deep peroneal nerve (L5, S1) Peroneus tertius note on extensor Digitorum longus 1. In the middle two-fourths of the fibula, the area of origin of this muscle is lateral to that of the extensor hallucis longus. Over the proximal phalanx, the tendon for each digit is expanded into a triangular dorsal digital expansion, which receives the insertions of interosseous and lumbrical muscles (12. This muscle may be regarded as the lower separated part of the extensor digitorum longus. Around the ankle, the deep fascia forms a number of thickened bands that hold underlying tendons in place. On the lateral side there are (much less prominent) superior and inferior peroneal retinacula. The tendons passing under cover of the extensor retinacula are (from medial to lateral side in 12. The relationship of the inferior extensor retinaculum to the tendons is as follows: a. The stem is in the form of a loop through which the tendons of the extensor digitorum and peroneus tertius pass. The superior limb has two layers one passing superficial to the extensor hallucis and the tibialis anterior, and the other deep to them. The inferior limb is superficial to these tendons; it may sometimes have an additional layer deep to the tendons. As they pass under the retinacula, the extensor tendons are surrounded by synovial sheaths (12. There is a gap between the areas of origin of this muscle from the head of the fibula and from the shaft. The muscle ends in a tendon that passes along a groove behind the lateral malleolus; here it is covered by the superior peroneal retinaculum. It passes just below the peroneal trochlea, where the tendon is covered by the inferior peroneal retinaculum. Thereafter, the tendon winds round the lateral side of the cuboid bone to reach its plantar aspect (12. This aspect of the cuboid bone bears a groove for the tendon (which is converted into a canal by the long plantar ligament). The muscle helps to maintain the arches of the foot (both longitudinal and transverse). Medial cuneiform bone (lateral side) Superficial peroneal Shaft of fibula (lower 1. Steadies the leg on the nerve (L5, S1, S2) surface) ing anterior to that of foot peroneus longus) 2. Tendon gets inserted into fifth metatarsal bone (lateral side of base) Peroneus brevis (Fibularis brevis) Chapter 12 Front and Lateral Side of Leg and the Dorsum of Foot 269 12. Because of the fact that the posterior border of the fibula turns medially in its lower part, the area of origin of the peroneus brevis (on the lateral surface) extends onto the posterior aspect of the bone. At the ankle the tendon passes behind the lateral malleolus: here it lies anterior to the tendon of the peroneus longus. It then runs forwards on the lateral surface of the calcaneus; here it lies above the longus tendon, the two being separated by the peroneal trochlea. The superior peroneal retinaculum is attached above to the lateral malleolus and below to the lateral surface of the calcaneus. The inferior peroneal retinaculum is attached below to the lateral surface of the calcaneus. As the tendons of the peroneus longus and brevis run downwards and forwards on the lateral side of the ankle, they are held in place by the superior and inferior peroneal retinacula. They are enclosed in a synovial sheath that is common to the two tendons above, but bifurcates below (12. The synovial tendon sheaths around the tendons of the peroneus longus and peroneus brevis may be inflamed. Occasionally, these tendons can be dislocated from their position behind the lateral malleolus. The anterior tibial artery begins as a terminal branch of the popliteal artery near the lower border of the popliteus muscle (12. Almost immediately, the artery turns forwards through the upper part of the interosseous membrane to enter the anterior compartment of the leg. It gradually passes medially so that in the lower part of the leg it comes to lie in front of the tibia. It terminates in front of the ankle joint, midway between the medial and lateral malleoli, by becoming continuous with the dorsalis pedis artery. In the upper part of the leg, the artery lies deep in the interval between the tibialis anterior (medially) and the extensor digitorum longus (laterally). In the middle of the leg, it is related laterally to the extensor hallucis longus. The tendon of this muscle crosses the artery from lateral to medial side above the ankle. For a short distance above the ankle the artery is covered only by skin, superficial fascia and deep fascia including the retinacula. Here it lies between the tendons of the extensor hallucis longus (medially) and the extensor digitorum longus (laterally). The artery is accompanied by the deep peroneal (anterior tibial) nerve which lies lateral to the artery. The anterior tibial recurrent artery ascends to take part in the anastomoses around the knee. The posterior tibial recurrent artery arises from the uppermost part of the anterior tibial artery in the back of the leg. Numerous muscular branches (m) supply muscles of the anterior compartment of the leg. The anterior lateral malleolar artery arises near the ankle and runs to the lateral malleolus. The anterior medial malleolar artery arises near the ankle and runs to the medial malleolus. Beginning in front of the ankle it runs forwards, downwards and medially on the dorsum of the foot to reach the space between the first and second metatarsal bones (12. Here it turns downwards through the space (between the two heads of the first dorsal interosseous muscle) to enter the sole of the foot. Medial to the artery there is the tendon of the extensor digitorum longus, and the medial terminal branch of the deep peroneal nerve. The medial tarsal branch goes to the medial side of the foot and ankle (Also see 12. The dorsal metatarsal arteries are connected to the arteries of the sole by two sets of perforating arteries: proximal and distal. The distal perforating arteries connect them to the plantar metatarsal branches of the plantar arch. The dorsalis pedis artery lies in front of the ankle where it can be palpated and pressed upon to stop bleeding. Veins of the Front of the Leg Superficial veins over the dorsum of the foot and the front of the leg have been described in Chapter 10. The anterior tibial artery is accompanied by venae comitantes that end in the popliteal vein. The fibres of this nerve are derived from ventral rami of spinal nerves: L4 to S3. Separating from the common peroneal at the junction of the middle and lower-thirds of the thigh it descends through the popliteal fossa, and passes into the back of the leg. The relations and branches of the tibial nerve in the leg will be described in Chapter 13. In the upper part of the popliteal fossa the nerve lies lateral to the popliteal artery and vein. At the upper angle of the popliteal fossa the nerve is covered by the semimembranosus medially, and by the biceps femoris (laterally). At the lower end of the fossa the nerve is covered by the overlapping margins of the medial and lateral heads of the gastrocnemius. Muscular branches given off in the lower part of the popliteal fossa supply the two heads of the gastrocnemius, the plantaris, the soleus and the popliteus (12. After running down superficial (posterior) to this muscle the nerve turns round its lower border to reach its anterior surface that it enters. The upper part of the tibial nerve gives three branches to the knee joint: They accompany the superior medial genicular, the middle genicular, and the inferior medial genicular arteries. Starting at the bifurcation of the sciatic nerve, it runs downwards and laterally along the lower part of the biceps femoris muscle to reach the head of the fibula. It winds round the lateral side of the neck of the fibula: as it does so it lies deep to the peroneus longus. Apart from these terminal branches the common peroneal nerve gives off the following branches: a. The lateral cutaneous nerve of the calf supplies the skin over the upper two-thirds of the lateral side of the leg. The area of supply also extends onto the anterior and posterior aspects of the leg. It runs downwards and medially across the lateral head of the gastrocnemius muscle to join the sural nerve along with which it is distributed. The foot is plantar flexed (as the dorsi flexors are paralysed, but the plantar flexors are not). Because of paralysis of the peronei (which are evertors) the foot may be inverted. There is loss of sensation in the areas of skin supplied by the deep peroneal and superficial peroneal nerves. It begins on the lateral side of the neck of the fibula, deep to the peroneus longus. It passes downwards and medially, enters the anterior compartment of the leg and descends in front of the interosseous membrane, and lower down on the anterior aspect of the shaft of the tibia. Accompanied by the anterior tibial artery it reaches the front of the ankle joint. In the leg the nerve gives branches to muscles of the anterior compartment: these are the tibialis anterior, the extensor hallucis longus, the extensor digitorum longus, and the peroneus tertius. This branch runs forwards on the dorsum of the foot along with the dorsalis pedis artery. It divides into two dorsal digital nerves that supply the adjacent sides of the great toe and the second toe. The metatarsophalangeal joint of the great toe receives a branch from the medial terminal branch. Excessive (or unaccustomed) use of muscles of the anterior compartment can lead to oedema in the compartment and pressure on the deep peroneal nerve. This nerve can also be compressed as it passes under the inferior extensor retinaculum in persons wearing tight boots. It is the nerve to muscles of the lateral compartment of the leg: these are the peroneus longus and the peroneus brevis. Reaching the lower part of the leg the nerve becomes superficial and supplies the skin on its lateral side. The medial branch gives one dorsal digital nerve to the medial side of the great toe; and another to the adjacent sides of the second and third toes. The lateral branch gives one dorsal digital nerve to the contiguous sides of the third and fourth toes and another to the adjacent sides of the fourth and fifth toes. CliniCal Correlation Superficial Peroneal Nerve the nerve can be stretched in atheletes.

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These fibres run through the pelvic splanchnic nerves to innervate pelvic viscera muscle relaxant used in dentistry buy 250 mg ponstel with visa. The spinal pathways carrying afferent impulses from the viscera are not fully established spasms brain best ponstel 500mg. These afferent fibres are peripheral process of pseudounipolar neurons located in the dorsal root ganglia of spinal nerves T1 to L2 or L3 (34 spasms from alcohol cheap 500 mg ponstel with amex. Some important points that may be noted about autonomic afferent are as follows: a quick spasms in lower abdomen discount ponstel 500mg with mastercard. Some normal visceral sensations that reach consciousness include those of hunger spasms pelvic floor purchase ponstel on line amex, nausea spasms from alcohol generic ponstel 500mg with mastercard, rectal distension and sexual sensations. Sensory impulses from the same organ may travel along both sympathetic and parasympathetic nerves. The nerve supply of individual organs has been described while describing the organs. To mark the deep inguinal ring draw a roughly circular area 1 cm above the midinguinal point. The third part of the duodenum lies transversely at the level of the subcostal plane. It is marked by two lines running upwards and to the left from the end of the third part. Sigmoid Colon the sigmoid colon is in the form of coils that lie predominantly in the true pelvis. This end lies just below the left nipple, in the left fifth intercostal space 9 cm from the median plane. Carry the line to the rightofthemiddleline(withaslightupwardconvexity)tillitreaches the place where the upper border of the right fifth costal cartilage is crossed by the right lateral line. To mark the lower border of the liver return to the front of the trunk and go back to the left end of the superior border(i. Fromheredrawalinerunning downwards and to the right so that it cuts the left costal margin over the tip of the left eighth costal cartilage. Carry the line downwards and to the right to the intersection of the transpyloric plane with the median plane. Crossing the median plane carry the line to the right costal margin which it should cut at the level of the tip of the ninth costal cartilage. Continue the two lines upwards and to the left till they reach the subcostal plane. The position of the kidneys relative to the anterior abdominal wall is shown in 35. Like the marking of the kidney the abdominal part of the ureter can also be marked from the front or from the back. Remember that the abdominal aorta lies more or less in the median plane and is about 2 cm broad. The lower end lies over a point about 1 cm below and to the left of the umbilicus. We have seen that the upper end of the abdominal aorta lies in the middle line about 2. The coeliac trunk can be represented as a small circle drawn in front of the aorta 1 cm below its upper end. Draw a broad line starting at the position of the coeliac trunk and passing upwards and to the left for about 10cm. The artery arises from the abdominal aorta a short distance below the origin of the coeliac trunk. The lower end lies at the point where the right lateral line cuts the transtubercular plane. This artery takes origin from the abdominal aorta and runs downwards and to the left. Its left edge should be about 1 cm to the right of the median plane and its right edge 2. It begins just below the transtubercular plane and ends opposite the sternal end of the right sixth costal cartilage. Draw a line from the lower end of the inferior vena cava to a point a little medial to the midinguinal point. The colon is outlined Chapter 35 Surface and Radiological Anatomy of the Abdomen 709 35. Asuitablecontrastmedium,administeredorally,hasbeen absorbed by the gut, and excreted by the liverinbile. Asthebileisconcentratedinthe gall bladder the organ is outlined Chapter 35 Surface and Radiological Anatomy of the Abdomen 711 35. Bones and Joints of the Head and Neck Vertebral Column Atypical Cervical Vertebrae the Skull the Mandible the Hyoid Bone Joints of Head and Neck the Atlanto-Axial Joints the Atlanto-Occipital Joints 37. Scalp, Face, Parotid Region and Lacrimal Apparatus the Scalp the Face Muscles of the Face Parotid Gland Vessels of the Face and Parotid Region Lymph Nodes of Head and Neck Nerves of the Face 38. Temporal and Infratemporal Regions Temporal Region Infratemporal Fossa Muscles of Mastication the Temporomandibular Joint 39. Submandibular Region and Tongue the Submandibular Gland the Sublingual Gland Suprahyoid Muscles the Tongue Muscles of the Tongue Blood Vessels, Lymphatics, and Nerves of the Tongue 40. Cranial Cavity and Vertebral Canal the Cranial Cavity the Meninges Nerves and Arteries in the Cranial Cavity the Spinal Cord 41. Muscles of the Neck, Triangles of the Neck, Deep Cervical Fascia and Lymph Nodes Muscles of the Neck the Platysma the Sternomastoid and Trapezius Infrahyoid Muscles 715 715 716 719 738 741 743 744 745 748 748 751 757 760 765 766 766 768 768 769 772 776 779 779 781 783 784 787 787 795 795 796 803 807 813 813 813 813 813 the Lateral Vertebral Muscles Anterior Vertebral Muscles (Prevertebral Muscles) Deep Muscles of the Back Triangles of the Neck the Posterior Triangle Subdivisions of the Anterior Triangle Suboccipital Triangle Deep Cervical Fascia Investing layer Pretracheal fascia Prevertebral fascia Carotid sheath Lymph Nodes of Head and Neck 42. Blood Vessels of Head and Neck Arteries the Common Carotid Arteries Internal Carotid Artery the External Carotid Arteries the Subclavian Arteries Veins the Internal Jugular Veins the Subclavian Veins the Intracranial Venous Sinuses Tributaries of Internal Jugular Veins in the Neck Other Veins of the Head and Neck 43. Nerves of the Head and Neck Cervical Nerves the Cervical Plexus and its Branches the Cranial Nerves Types of Fibres in Peripheral Nerves Cranial Nerve Nuclei the Olfactory Nerves the Optic Nerve the Oculomotor Nerve the Trochlear Nerve the Abducent Nerve the Trigeminal Nerve the Ophthalmic Nerve the Maxillary Nerve the Facial Nerve the Vestibulocochlear Nerve the Glossopharyngeal Nerve the Vagus Nerve the Accessory Nerve the Hypoglossal Nerve Cervical Part of Sympathetic Trunk 44. Orbit, Eye and Ear the Orbit 814 815 815 821 823 824 826 827 827 828 828 828 829 833 833 833 834 838 847 854 854 855 855 860 861 868 868 870 874 875 879 883 884 887 891 891 893 895 898 908 916 918 923 927 929 931 935 935 Contents of the Orbit Muscles of the Orbit the Lacrimal Gland Nerves and Vessels of Orbit the Eyeball the Ear and Some Related Structures the Auricle External Acoustic Meatus the Middle Ear the Internal Ear 45. Oral Cavity, Nasal Cavity, Pharynx, Larynx, Trachea and Oesophagus the Oral Cavity and Some Related Structures the Oral Cavity the Palate Muscles of the Soft Palate the Teeth the Nasal Cavities and Paranasal Sinuses the Paranasal Sinuses the Pharynx Muscles of the Pharynx the Palatine Tonsils the Larynx Interior of the Larynx Muscles of the Larynx the Trachea the Oesophagus 46. Endocrine Glands of the Head and Neck, Carotid Sinus and Carotid Body the Hypophysis Cerebri the Pineal Body the Thyroid Gland the Parathyroid Glands the Carotid Sinus the Carotid Bodies and Paraganglia 47. Introduction to Central Nervous System and Internal Structure of Spinal Cord Introduction to the Central Nervous System Internal Structure of Spinal Cord 935 935 939 940 943 953 955 956 957 969 976 976 976 978 978 981 984 988 991 994 996 998 1000 1002 1005 1006 1007 1007 1013 1014 1019 1020 1021 1022 1022 1022 1023 1023 1025 1025 1026 1028 1033 1033 1037 49. Gross Anatomy of Brain Gross Anatomy of the Brainstem Preliminary Review of the Internal Structure of the Brainstem Gross Anatomy of the Cerebellum Gross Anatomy of the Cerebral Hemispheres An Introduction to Some Structures Within the Cerebral Hemispheres Important Functional areas of the Cerebral Cortex White Matter of Cerebral Hemispheres 50. Tracts of Spinal Cord and Brainstem; and Cerebellar Connections Tracts of Spinal Cord and Brainstem Descending Tracts Ending in the Spinal Cord Descending Tracts Ending in the Brainstem Ascending Tracts Connections of the Cerebellum Cerebellar Peduncles 51. Diencephalon, Basal Ganglia, Olfactory Region and Limbic System the Diencephalon the Thalamus the Hypothalamus the Metathalamus the Epithalamus the Subthalamic Region the Basal Ganglia the Olfactory Region and Limbic System the Olfactory Region the Olfactory Pathway the Limbic System 53. Pathways for Special Senses Visual Pathway Pathway for Hearing Pathways for Taste Pathways for Smell 55. Ventricles of the Brain and Cerebrospinal Fluid the Lateral Ventricles the Third Ventricle the Fourth Ventricle the Cerebrospinal Fluid 56. Here we will consider some additional features of typical cervical vertebrae, and also some atypical cervical vertebrae. Each transverse process of a typical cervical vertebra is pierced by a foramen transversarium (36. The part of the process in front of the foramen is called the anterior root; and the part behind it is called the posterior root (36. The part lateral to the foramen is usually called the costotransverse bar, but it is more correct to call it the intertubercular bar. The anterior and posterior roots end in thickenings called the anterior and posterior tubercles respectively. One cervical nerve lies in this groove after it passes out of the intervertebral foramen. In the cervical region the costal element forms the anterior root, the costotransverse bar, and both the anterior and posterior tubercles. The laminae of cervical vertebrae are long (transversely) and narrow (vertically). The superior and inferior articular processes form a solid articular pillar that helps to transmit some weight from one vertebra to the next lower one. It looks very different from a typical cervical vertebra as it has no body, and no spine (36. It consists of two lateral masses joined, anteriorly, by a short anterior arch; and, posteriorly, by a much longer posterior arch. A large transverse process, pierced by a foramen transversarium, projects laterally from the lateral mass. The superior aspect of each lateral mass shows an elongated concave facet that articulates with the corresponding condyle of the occipital bone (to form an atlanto-occipital joint). Nodding and lateral movements of the head take place at the two (right and left) atlanto-occipital joints. The medial side of the lateral mass shows a tubercle that gives attachment to the transverse ligament of the atlas (shown in dotted line in 36. This ligament divides the large foramen (bounded by the lateral masses and the arches) into anterior and posterior parts. The anterior part is occupied by the dens (which is an upward projection from the body of the axis). The dens articulates with the posterior aspect of the anterior arch, that bears a circular facet for it. The dens also articulates with the transverse ligament, these two articulations collectively forming the median atlanto-occipital joint. In side-to-side movements of the head the atlas moves with the skull around the pivot formed by the dens. The posterior arch bears a similar projection, the posterior tubercle, which may be regarded as a rudimentary spine. The vertebral artery passes upwards through the foramen transversarium and then runs medially on the groove over the posterior arch. The first cervical nerve crosses the posterior arch deep to the vertebral artery and divides here into anterior and posterior primary rami. The most conspicuous feature of the axis, that distinguishes it from all other vertebrae, is the presence of a thick finger-like projection arising from the upper part of the body. The dens fits into the space between the anterior arch of the atlas and its transverse ligament to form the median atlanto-occipital joint. The anterior aspect of the dens bears a convex oval facet for articulation with the anterior arch. On either side of the dens, the axis vertebra bears a large oval facet for articulation with the corresponding facet on the inferior aspect of the atlas. It is small and ends in a single tubercle corresponding to the posterior tubercle of a typical cervical vertebra. The seventh cervical vertebra differs from a typical vertebra in having a long thick spinous process that ends in a single tubercle (36. Note that the vertebral artery and vein do not traverse the foramen transversarium of this vertebra. If the gap between the neural arches is small no obvious deformity may be apparent on the surface (spina bifida occulta: occult = hidden). Two or more cervical vertebrae may be fused to one another resulting in a short neck (Klippel-Feil syndrome). The atlas vertebra may be fused to the occipital bone (occipitalisation of atlas). In the condition called infantile torticolis, the mastoid process of one side is pulled towards the sternoclavicular joint of the same side. The condition (previously regarded as congenital) is now believed to be a result of injury to the sternocleidomastoid muscle during birth, and its gradual fibrosis. The altered position of the neck leads to deformity of cervical vertebrae that may become wedge shaped. The torticolis is often preceeded by a swelling (tumour) on the sternocleidomastoid. Degenerative changes taking place in the cervical spine, with age, often lead to stiffness and pain in the neck (cervical spondylosis). The intervertebral joints undergo inflammation that is associated with the formation of bony outgrowths (osteophytes). The outgrowths can encroach on intervertebral foramina narrowing them so that cervical nerves may be pressed upon. Such pressure (accentuated by the presence of oedema) can lead to pain that often radiates into the upper limb. In the thoracic and lumbar regions of the vertebral column adjoining vertebrae are maintained in position by close interlocking of the articular processes. Dislocation of the vertebral column can take place only after fracture of the articular processes. However, in the cervical region the articular surfaces are flat and almost horizontal, so that dislocation is possible without fracture. Dislocation and fracture of the vertebral column are very serious because of damage to the spinal cord. In death by hanging, the dens (of the axis) dislocates backwards (by tearing through the transverse ligament of the atlas), and crushes the lower medulla and the spinal cord. A cervical vertebra (usually the atlas) may slip forwards over the next vertebra even in the absence of injury (cervical spondylolisthesis). It is a difficult part of the skeleton to study as there is a very large number of named features on it, and many of these are difficult to identify. The other bones of the skull are firmly united to one another at joints called sutures. Its upper and posterior part contains a large cranial cavity in which the brain lies. Anteriorly, and inferiorly, the cranium forms the skeleton of the face including the walls of the orbits (in which the eyeballs lie), the cavity of the nose, and the upper part of the cavity of the mouth.

The lower ridge is the wall of a canal through which the facial nerve runs backwards muscle relaxant tinnitus discount 500 mg ponstel. Occasionally muscle relaxant eperisone order discount ponstel on line, this bone may be missing and the nerve may lie just under the mucosa muscle relaxant klonopin buy ponstel 250 mg low price. Running backwards across the medial wall of the middle ear muscle relaxant natural generic 500mg ponstel with amex, the facial canal reaches the aditus to the mastoid antrum quadricep spasms discount ponstel 250mg on line. Here spasms jerks cheap ponstel online mastercard, it bends downwards and runs through bone just behind the angle between the medial and posterior walls of the middle ear to reach the stylomastoid foramen (See 43. The stapedius is a small muscle lying in a bony canal that is related to the posterior wall of the middle ear. Posteriorly and below, this canal is continuous with the vertical part of the canal for the facial nerve. They end in a tendon that enters the middle ear through the pyramid and runs forwards to be inserted into the posterior surface of the neck of the stapes. The tensor tympani lies in a canal that opens into the anterior wall of the middle ear. The muscle ends in a tendon that reaches the middle ear cavity near its medial wall. Here, it bends sharply to the lateral side by passing around the processus trochleariformis. Both the tensor tympani and the stapedius protect the ear against very loud sounds by restricting the vibrations of the tympanic membrane and the ossicles. Paralysis of the muscles (specially of the stapedius) gives rise to a condition called hyperacusis in which even normal sounds appear too loud. Furthermore, infection may spread from it to neighbouring structures with serious consequences. Superiorly, the roof of the antrum is formed by the tegmen tympani that separates it from the middle cranial fossa; and from the temporal lobe of the cerebral hemisphere. Inferiorly, the mastoid antrum is continuous with the mastoid air cells (see below). Anteriorly, below the aditus, the antrum is related to the facial nerve as it descends within its bony canal. Medially, behind the aditus, the antrum is related to the posterior semicircular canal. The lateral wall of the mastoid antrum is related to the suprameatal triangle (44. Anteroinferiorly by the posterosuperior margin of the (bony) external acoustic meatus. Posteriorly by a vertical line drawn as a tangent to the posterior margin of the meatus. The thickness of bone separating the mastoid antrum from the surface of the skull is only about 2 mm at birth, but it increases by about 1 mm for every year of age until it is about 13 to 14 mm thick. These are a series of intercommunicating spaces of variable size present within the mastoid process. Occasionally, they may extend beyond the mastoid process into the squamous or petrous parts of the temporal bone. In the medial part of the petrous temporal bone in relation to the internal ear, the carotid canal, the auditory tube, and the abducent nerve. Infection can reach the mastoid air cells though the tympanic cavity and the mastoid antrum, and can spread to any of the structures related to them. Because of this communication air passes into the tympanic cavity (and into the mastoid antrum and air cells). When we suddenly ascend to a higher altitude (as in going up a hill in a car) the air pressure on the outside of the tympanic membrane falls, but that on its inner side remains the same as before. This inequality in pressure gives rise to a change in the quality of sound perceived. However, on swallowing of saliva, and the consequent equalisation of pressure, the sound suddenly returns to normal. The same phenomenon takes place much more acutely during the take off of an aircraft, and can give rise to distress in the ear; more so in persons who have a mild infection. The communication between the pharynx and the middle ear is a path along which infection frequently reaches the middle ear. This occurs more commonly in children, in whom the auditory tube is shorter and wider than in the adult. When this happens air within the tympanic cavity is gradually absorbed and pressure on the outside of the tympanic membrane becomes greater than on the inside. This can give rise to discomfort that can be relieved by introducing air into the auditory tube through a catheter. If obstruction to the auditory tube is prolonged pus can accumulate in middle ear resulting in severe pain. The pus may burst through the tympanic membrane leading to discharge from the ear, and to the formation of a perforation in the membrane. It is for these reasons that the anatomy of the auditory tube is of much practical importance. The lateral end of the bony part opens on the anterior wall of the middle ear (44. The medial end of the bony part opens on the base of the skull (at the lateral end of the groove between the anterior margin of the petrous temporal bone and the posterior margin of the greater wing of the sphenoid bone). The cartilaginous part extends from the medial end of the bony part to the lateral wall of the nasopharynx. The auditory tube is narrowest at the junction of the bony and cartilaginous parts: this part is called the isthmus. The cartilage forming the wall of the auditory tube is not tubular, but consists of a triangular plate that is bent on itself. Its medial end is broad and lies just under the mucous membrane of the lateral wall of the nasopharynx where it forms the tubal elevation. The cartilage consists of a larger medial lamina (facing backwards and medially) and of a smaller lateral lamina (facing forwards and laterally). The cartilaginous part of the auditory tube lies in close relation to the base of the skull in the groove between the anterior margin of the petrous temporal bone and the posterior margin of the greater wing of the sphenoid bone. The interior of the auditory tube is lined by mucous membrane continuous with that of the nasopharynx and of the middle ear. The cartilaginous part of the auditory tube lies in close relationship to the roof of the infratemporal fossa (44. The tensor palati muscle lies immediately to its lateral side, and the levator palati lies immediately medial to it. The part of the tensor palati arising from the tube is believed to be responsible for opening the auditory tube during swallowing. The tensor palati separates the tube from several structures in the infratemporal fossa including the mandibular nerve, the chorda tympani, the middle meningeal artery and the otic ganglion. The middle ear receives several small branches that arise from arteries that lie in its neighbourhood. The veins of the middle ear drain downward (along the auditory tube) towards the infratemporal fossa where they end in the pterygoid plexus. Some veins drain through apertures in the petrous temporal bone to end in the superior petrosal sinus. The lymphatics from the middle ear and the mastoid air cells end in the parotid lymph nodes while those from the auditory tube reach the deep cervical nodes (44. The nerves supplying the mucous membrane of the middle ear, the mastoid antrum and air cells and the auditory tube are derived from the tympanic plexus that lies over the promontory. The tympanic plexus is formed mainly by branches from the tympanic branch of the glossopharyngeal nerve. The tympanic plexus gives off the lesser petrosal nerve, which ends in the otic ganglion. The internal ear is in the form of a complex system of cavities within the petrous temporal bone. Because of the complex shape of these intercommunicating cavities the internal ear is referred to as the labyrinth. The basic arrangement of the labyrinth is best understood by looking at a transverse section through a relatively simple part of it like a semicircular canal (44. Lying within the bony labyrinth, there is a system of ducts which constitute the membranous labyrinth. In the central part of the bony labyrinth, there is a cavity called the vestibule. Posteriorly, the cavity of the vestibule is continuous with the three semicircular canals (44. The part of the membranous labyrinth within each semicircular canal is called a semicircular duct [It is important to distinguish carefully between the terms semicircular canal, and semicircular duct]. The part of the membranous labyrinth lying in the vestibule is represented by two distinct membranous sacs called the saccule and the utricle. The utricle and the saccule communicate with each other through the utriculosaccular duct. The utriculosaccular duct is also connected to a diverticulum called the saccus endolymphaticus. Its lateral wall is formed by the part of the same plate of bone that forms the medial wall of the middle ear. In this wall, there is an aperture, the fenestra vestibuli, through which the vestibule and middle ear communicate. The plate of bone that forms the medial wall of the vestibule closes the inner end of the internal acoustic meatus. There are three semicircular canals, anterior (or superior), posterior, and lateral (44. The non-ampullated ends of the anterior and posterior canals join to form a common channel, the crus commune. The anterior and posterior canals are both vertical, while the lateral canal is horizontal. The plane of the posterior canal is parallel to the long axis of the petrous temporal bone. The anterior canal of one side lies in the same plane as the posterior canal of the opposite side. The diameter of the tube is greatest at its junction with the vestibule, and this part is called the basal turn of the cochlea. The tube becomes progressively narrower towards the centre or apex of the cochlea. The basal turn of the cochlea produces an elevation, the promontory, on the medial wall of the middle ear. The apex of the cochlea is related to this wall of the middle ear just in front of the promontory. The scala vestibuli and the scala tympani are partially separated from each other by a shelf of bone. The shelf follows the coiling of the cochlea and is, therefore, called the spiral lamina. Further details of the cochlea can be appreciated if we study a transverse section through one turn of the cochlea (44. The spiral lamina ends just short of the apex of the cochlea so that the scala vestibuli becomes continuous with the scala tympani at the apex (44. The part of the membranous labyrinth in the cochlea is called the duct of the cochlea. Fibres arising from the ganglion pass through the spiral lamina to supply the spiral organ (See below). The membranous labyrinth lying within each semicircular canal forms a semicircular duct [It is important to distinguish carefully between the terms semicircular canal, and semicircular duct]. The part of the membranous labyrinth lying within the vestibule is represented by two distinct membranous sacs called the saccule and the utricle. This sac lies outside the bony labyrinth on the posterior surface of the petrous temporal bone. Traversing the entire length of the scala tympani, it reaches the secondary tympanic membrane (which closes the fenestra cochleae) causing it to bulge into the middle ear. Distortions produced in these cells as a result of vibrations generate nervous impulses. Central processes arising from neurons of the spiral ganglion constitute the cochlear nerve. Information about changes in the position of the head is provided by end organs called maculae (singular = macula) present in the utricle and saccule. With changes in the position of the head, the otoliths are displaced leading to distortion of hair cells. Information about angular movements (acceleration) of the head is provided by end organs called the ampullary crests (or cristae ampullae) one of which is present in the ampulla of each semicircular duct. Each crista consists of hair cells (and supporting cells) that are surmounted by a gelatinous covering that forms a partition (cupola) within the ampulla. Movements of the head produce currents in the endolymph within the semicircular ducts. These cause the cupolae to move resulting in deformation of hair cells and production of nerve impulses. The internal ear is supplied by the labyrinthine artery which usually arises from the anterior inferior cerebellar artery. The internal ear also receives some twigs from the stylomastoid artery that supplies the middle ear. The internal ear drains into veins that end in the superior petrosal sinus or in the transverse sinus. The anatomy of the external acoustic meatus, of the middle ear, and of the mastoid antrum is of great clinical importance as these are frequent sites of infection.