Usmle step 1 pearls

Danil Hammoudi.MD

SINOE MEDICAL ASSOCIATION

SURGICAL ANATOMY PART 1

 

 

 

 

 

 

 

 

 

Ø      Lymphatic fluid from the entire body below the respiration diaphragm as well as the left upper quadrant drains into the thoracic ducy.

Ø      The thoracic duct empties into the systemic venous circulation where the left internal jugular and left subclavian veins joiun in the base of the neck on the left.

Ø      Lymph from the right upper quadrant drains into the right lymphatic duct, which joins the junction of the right internal jugular and subclavian veins on the right.

a= esophagus, b= trachea, c= right primary bronchus, d= left primary bronchus, e= pericardial sac, f= line indicating site of adherence of the pericardium to the diaphragm, g= inferior vena cave, h= superior vena cave, i= azygos vein, k= right brachiocephalic vein, l= right internal jugular vein, m= right subclavian vein, n= right external jugular vein, o= left internal jugular vein, p= left subclavian vein, q= left external jugular vein, I= branches of the right pulmonary artery, s= branches of the left pulmonary artery, t,u= right and left pulmonary vein, v= aortic arch at its posterior extremity, x,y= common carotid artery, z= left subclavian artery, &= vertebral artery branch of left subclavian; 1= right subclavian artery, 2= dilated conus at origin of right subclavian artery, 3= descending (thoracic) artery, 4= thoracic duct, 5= arch of thoracic duct, 6= division of duct into two branches, 7= minor branch of thoracic duct, 8= major branch of thoracic duct, small thoracic duct on the left side.

·         Groups of lymph nodes form a ring around the head Submental nodes inferior and posterior to chin Submandibular nodes inferior to mandible, some extend superior into buccal cheek Superficial cervical near angle of mandible Preauricular or Parotid nodes just anterior to ear Postauricular or Mastoid nodes Occipital nodes ·         Upper Deep and Lower Deep Cervical nodes divided by omohyoid muscle subclavian & internal jugular become brachio-cephalic or thoracic duct

 

Lymphatic vessels which ultimately converge as the Thoracic Duct and drain their contents into the right and left subclavian veins in the thorax. In summary the lymphatic system serves as a slow flowing, low pressure drainage system that collects a small portion of the interstitial fluid from throughout the body and returns it to the bloodstream. The Thoracic Duct arises anterior to the second lumbar vertebra as enlarged sac, beginning as the cisterna chyli. This sac like lymphatic mass collects lymph from lower limbs of the body as well as the digestive system.

 

 

 

 

The lymphatic circulation as a drainage system

The lymphatic system has neither a heart nor arteries. Its microscopic dead-end capillaries extend into most tissues, paralleling the blood capillaries.

The lymphatic circulation is a drainage system. Its job in maintaining fluid balance is to:

	collect excess interstitial fluid and return it to the blood (approximately 3 litres daily).
	return plasma proteins to the blood.

Ø      Once interstitial fluid enters a lymph capillary, it is referred to as lymph.

Ø      The three main types of lymphatic vessels are lymph capillaries, lymphatics, and lymph ducts.

Ø      Lymph capillaries are microscopic tubes located between cells. Lymph capillaries resemble blood capillaries somewhat, but differ in important ways. Whereas a blood capillary has an arterial and a venous end, a lymph capillary has no arterial end. Instead, each lymph capillary originates as a closed tube. Lymph capillaries also have a larger and more irregular lumen (inner space) than blood capillaries and are more permeable.

Ø      The wall of a lymph capillary is constructed of endothelial cells that overlap one another.

Ø      When fluid outside the capillary pushes against the overlapping cells, they swing slightly inward--like a swinging door that moves in only one direction. Fluid inside the capillary cannot flow out through these openings

Ø      Note the internal valve which allows the lymph to flow in one direction only.

Ø      Lymph capillaries branch and interconnect freely and extend into almost all tissues of the body except the CNS (Central Nervous System) and the avascular tissues such as the epidermis and the cartilage.

Ø      Lymph capillaries join to form larger vessels called lymphatics or lymph veins. These resemble blood-conducting veins but have thinner walls and relatively larger lumen, and they have more valves. In the skin, lymphatics are located in subcutaneous tissue and follow same paths as veins. In the viscera, lymphatics generally follow arteries and form plexuses (networks) around them.

Ø      At certain locations lymphatics enter lymph nodes. These are structures that consist of lymphatic tissue.

Ø      As the lymph flows slowly through the lymph sinuses within the tissue of the lymph node, it is filtered. Macrophages remove bacteria and other foreign matter as well as debris.

Ø      Lymphocytes are added to the lymph as it flows through the sinuses of a lymph node. Thus the lymph leaving the node is both cleaner of debris and richer in lymphocytes. Lymphatics leaving lymph nodes are called efferent lymph vessels and conduct lymph toward the shoulder region. Large lymphatics that drain groups of lymph nodes are often called lymph trunks.

Ø      Lymphatics from the lower portion of the body converge to form a dilated lymph vessel, the cisterna chyli, in the lumbar region of the abdominal cavity. The cisterna chyli extends for about 6 centimetres just to the right of the abdominal aorta. At the level of the twelfth thoracic vertebra, the cisterna chyli narrows and becomes the thoracic duct.

Ø      Lymphatic vessels from all over the body, except the upper right quadrant, drain into the thoracic duct. This vessel delivers the lymph into the base of the left subcIavian vein at the junction of the left subcIavian and internal jugular veins. In this way lymph is continuously emptied into the blood where it mixes with the plasma. At the junction of the thoracic duct and the venous system, a valve prevents blood from flowing backward into the duct.

Ø      Only about 1 centimetre in length, the right lymphatic duct receives lymph from the lymphatic vessels in the upper right quadrant of the body. The right lymphatic duct empties lymph into the base of the right subclavian vein (at the point where it unites with the internal jugular vein to form the brachiocephalic)

Ø      An example of the pattern of lymph circulation is:

Ø      Lymph capillaries lymphatic  lymph node   lymphatic cisterna chyli thoracic duct

Ø      Lymphatic vessels and lymph nodes can be visualised by the process of lymphangiography. A radiopaque (not transparent to x-rays) contrast material is injected into the a lymphatic vessel. This will show up the vessel and it’s connections to other lymph vessels. The fluid is left in the system for 24 hours and the lymph nodes can then be observed by X-rays. This technique is quite important in the treatment of neoplasms and other disorders of the lymphatic system. The technique is also used to locate lymph nodes for radiation therapy or for surgical removal.

Role of the lymphatic system in fat absorption and transport [SEE LIPID BIOCHEMISTRY AND PHYSIOLOGY]

Ø      Small quantities of very small fatty acids are able to directly enter the intestinal capillaries of the villi of the small intestine and hence enter the blood stream in this way.

Ø      However, the majority of fatty acids are long chained and are absorbed quite differently.

Ø       Within the intestinal lumen, bile salts form aggregates called micelles that are water soluble.

Ø      Fatty acids and monoglycerides are aggregated into the centres of the micelles.

Ø      The micelles transport the fatty acids and monoglycerides to the brush borders of the villi.

Ø      From here, the fatty acids and monoglycerides diffuse into the epithelial cells of the villi.

Ø      The micelles continue their ferrying function in the intestinal lumen.

Ø       Within the epithelial cells, the fatty acids and monoglycerides are resynthesised into triglycerides.

Ø      The triglycerides combine with cholesterol, lipoprotein, and phospholipids to form globules called chylomicrons.

Ø      The chylomicrons leave the epithelial cells and enter into the lacteal of the villus. Lymphatic vessels then carry the chylomicrons to the venous blood of the left subclavian vein via the thoracic duct.

Functions of lymph nodes

Filtering and phagocytosis

Lymph is filtered by the reticular and lymphoid tissue as it passes through lymph nodes. Particulate matter may include microbes, dead and live phagocytes containing ingested microbes, cells from malignant tumours, worn out and damaged tissue cells, and inhaled particles. Organic material is destroyed in the lymph nodes by macrophages and antibodies. Some inorganic inhaled particles cannot be destroyed by phagocytosis. These remain inside the macrophage either causing no damage or destroying it. Material not filtered off and dealt with in one lymph node passes on to the next and so on. Thus by the time the lymph reaches the blood it has usually been cleaned of all impurities such as cell debris and foreign bodies. In some instances where phagocytation is incomplete the node may swell. Swelling of lymph nodes is often an indication of an infection. You may well have experienced swollen cervical lymph nodes. These often accompany a sore throat due to streptoccocal infection. Infections in almost any part of thre body may result in swelling and tenderness of the lymph nodes associated with that part of the body.

Proliferation of lymphocytes

Activated T- and B- lymphocytes multiply in the lymph nodes. T- and B- Lymphocytes are added to the lymph as it flows through the sinuses of a lymph node. Thus the lymph leaving the node is richer in lymphocytes.  Antibodies produced by the B- lymphocytes enter the lymph and the blood draining the node.

 

 

 

 

 

 

       The Face is divided into two parts- the upper and outer lymphotome, and the middle lymphotome. The upper part drains outward and downward into the perotid nodes, then down the cervical chain , to the terminus and into the blood stream.

The center and lower lymphotome drains the lymph into the submandiblular nodes, then down the cervical chain, to the terminus and into the blood stream.

The lateral part of the breast drains out towards the axillary nodes. The upper medial part drains into the sternal nodes, which then drain up to the terminus and into the blood stream. The lower medial portion drains deep into the torso.

 

 

Lymphatics of the Thorax - Listed Alphabetically
Structure	Location	Afferents from	Efferents to	Regions drained	Notes
anterior mediastinal nodes	along the course of the brachiocephalic vessels and aorta	lymphatic vessels from the anterior mediastinum and middle mediastinum	bronchomediastinal trunk	thymus, anterior respiratory diaphragm, pericardium, part of the heart	anterior mediastinal nodes are from 2 to 5 in number
axillary nodes	axilla	cubital nodes; lymphatic vessels from the upper limb, thoracic wall and subscapular region	efferents vessels form the subclavian trunk, some drainage to inferior deep cervical nodes	upper limb, most of the mammary gland, some of the anterolateral chest wall, posterior thoracic wall and scapular region	axillary nodes number from 20 to 30 and are organized in five groups based on their position within the axilla: 1) pectoral nodes, along the lateral border of the pectoralis major m.; 2) lateral nodes, located along the distal axillary v.; 3) central nodes, centrally located along axillary v.; 4) subscapular nodes, located along the subscapular v. and its tributaries; 5) apical nodes, located at the apex of axilla
axillary nodes, apical	apex of the axilla	lateral axillary nodes; central axillary nodes; subscapular axillary nodes; pectoral nodes; accessory lymphatic vessels from the mammary gland; lymphatic vessels accompanying the cephalic v.	subclavian lymphatic trunk; deep cervical lymph nodes	upper limb, most of the mammary gland, some of the anterolateral chest wall, posterior thoracic wall and scapular region	apical axillary nodes are 6- 12 in number; this is the highest node group in the axilla and all other node groups drain through these nodes; a very important group of nodes in cases of metastatic spread of breast cancer; connections to deep cervical nodes may result in spread of breast cancer through the deep neck
axillary nodes, central	in the fat of the axilla	lateral axillary nodes; pectoral nodes; subscapular nodes; lymphatic vessels from the mammary gland and upper limb	apical axillary nodes	upper limb, most of the mammary gland, some of the anterolateral chest wall, posterior thoracic wall and scapular region	central axillary nodes are 4 or 5 in number; they are involved in cancer of the mammary gland
axillary nodes, lateral	along the distal axillary v.	cubital nodes; lymphatic vessels of the arm	central axillary nodes, apical axillary nodes	upper limb	lateral axillary nodes become inflamed during upper limb infections; also known as: brachial nodes
axillary nodes, subscapular	along the course of the subscapular vessels	lymphatic vessels from the skin of the back and back of the neck; lymphatic vessels from the muscles of the scapular region	central axillary nodes	skin of the back and back of the neck; muscles of the scapular and subscapular regions	subscapular axillary nodes are 5 or 6 in number; also known as: posterior axillary nodes
bronchomediastinal trunk	along the course of the brachiocephalic v.	union of efferents from the paratracheal nodes, parasternal nodes and anterior mediastinal nodes	left: thoracic duct; right: right lymphatic duct	thoracic wall and viscera; medial part of the mammary gland	right bronchomediastinal trunk receives lymph from the lower lobe of the left lung; bronchomediastinal trunk may drain directly into the venous system on either side
bronchopulmonary nodes	hilum of the lung	pulmonary nodes	tracheobronchial nodes	lung	bronchopulmonary nodes are also known as: hilar nodes
cisterna chyli	between the abdominal aorta and the inferior vena cava anterior to the body of the L1 or L2 vertebra	right and & left lumbar trunks; possibly the intestinal trunk	thoracic duct	all of the body below the respiratory diaphragm; all of the abdominal and pelvic viscera	cisterna chyli is an enlargement of the lower end of the thoracic duct; it occurs in about 25% of individuals
hilar nodes	at hilum of lung	pulmonary nodes	tracheobronchial nodes	lung	also known as: bronchopulmonary nodes
infraclavicular nodes	along the cephalic v. in the deltopectoral groove	lymphatic vessels from the superficial upper limb	apical axillary nodes	skin and superficial fascia of the upper limb	infraclavicular nodes may become inflamed during infections of the superficial tissues of the upper limb
intercostal nodes	near the heads of the ribs	lymphatic vessels from the intercostal space	cisterna chyli/thoracic duct, jugulosubclavian duct	intercostal space and posterolateral thoracic wall	usually two nodes occur in each intercostal space
mediastinal nodes, anterior	along the course of the brachiocephalic vessels and aorta	lymphatic vessels from the anterior mediastinum and middle mediastinum	bronchomediastinal trunk	thymus, anterior respiratory diaphragm, pericardium, part of the heart	anterior mediastinal nodes are from 2 to 5 in number
mediastinal nodes, posterior	along azygos system of veins and esophagus	viscera of the posterior mediastinum and chest wall	thoracic duct, inferior tracheobronchial nodes, superior tracheobronchial nodes	posterior mediastinum, posterior aspect of the heart and pericardium, posterior part of the respiratory diaphragm	posterior mediastinal nodes drain primarily to the thoracic duct
parasternal nodes	lateral border of sternum, along the course of the internal thoracic vessels	anterior phrenic nodes, lymphatic vessels from the anterior thoracic wall	larger lymphatic vessels in the root of the neck	medial side of the mammary gland; medial part of the anterior chest wall and muscles	parasternal nodes constitute an important drainage pattern in cases of cancer of the mammary gland; one or two parasternal nodes may be found in the anterior end of intercostal spaces 1-6; also known as: sternal nodes
paratracheal nodes	coursing along the lateral surface of the trachea and esophagus	superior tracheobronchial nodes	bronchomediastinal trunk	lungs, trachea, upper esophagus, the part of the larynx below the vocal folds	paratracheal nodes are an important group of nodes in cases of pulmonary infection or lung cancer; also known as: tracheal nodes
pectoral nodes	along the lateral border of the pectoralis major m. along the course of the lateral thoracic vessels	lymphatic vessels from the mammary gland and anterolateral thoracic wall	central axillary nodes	anterolateral thoracic wall and muscles; most of the mammary gland	an important group of nodes to examine during a breast physical exam; also known as: anterior axillary nodes
phrenic nodes	on the thoracic surface of the respiratory diaphragm	lymphatic vessels from the diaphragm, liver and thoracic wall	lumbar nodes, posterior mediastinal nodes	superior surface of the liver, respiratory diaphragm	phrenic nodes drain two structures that are very closely related in developmental origin - the liver and diaphragm (septum transversum); three subgroups of phrenic nodes are recognized: anterior, middle and posterior
posterior mediastinal nodes	along azygos system of veins and esophagus	viscera of the posterior mediastinum and chest wall	thoracic duct, inferior tracheobronchial nodes, superior tracheobronchial nodes	posterior mediastinum, posterior aspect of the heart and pericardium, posterior part of the respiratory diaphragm	posterior mediastinal nodes drain primarily to the thoracic duct
pulmonary nodes	within the lung parenchyma	lymphatic vessels from the parenchyma of the lung	bronchopulmonary (hilar) nodes	lung parenchyma, bronchial tree within the lungs	pulmonary nodes are located along the larger bronchi of the lung
sternal nodes	lateral border of sternum, along the course of the internal thoracic vessels	anterior phrenic nodes, lymphatic vessels from the anterior thoracic wall	larger lymphatic vessels in the root of the neck	medial side of the mammary gland; medial part of the anterior chest wall and muscles	sternal nodes constitute an important drainage pattern in cases of cancer of the mammary gland; one or two sternal nodes may be found in the anterior end of intercostal spaces 1-6; also known as: parasternal nodes
subclavian trunk	along the course of the subclavian v.	apical axillary nodes; infraclavicular nodes	drains into the junction of the internal jugular v. and the subclavian v.	upper limb, most of breast, anterolateral chest wall	subclavian lymphatic trunk occasionally drains into the thoracic duct on the left side; on the right it occasionally drains into the right lymphatic duct
supraclavicular nodes	in and around carotid sheath below level of omohyoid	superior deep cervical nodes, transverse cervical nodes, spinal accessory nodes	efferents form the jugular lymphatic trunk	head and neck	also known as: inferior deep cervical nodes
thoracic duct	between the esophagus anteriorly and the thoracic vertebral bodies posteriorly	formed by the union of the lumbar lymph trunks, sometimes dilated to form a cisterna chyli	junction of the left subclavian v. and the left internal jugular v.	all of the body and limbs below the respiratory diaphragm; the left side of the chest, left upper limb and the left side of the head and neck above the diaphragm	thoracic duct is the largest lymphatic vessel; it passes through the aortic hiatus on the right side of aorta; it swings to the left side of the esophagus at the T4-T5 intervertebral disc (at the level of the sternal angle)
thymus	root of the neck and superior mediastinum posterior to sternum	none	parasternal nodes	essential for normal development of the immune system maturation	thymus involutes at puberty and is mostly replaced by a mass of fat
tracheobronchial nodes	along the trachea, around the tracheal bifurcation and primary bronchi	lymphatic vessels from the lung	bronchomediastinal lymph trunk	lungs, visceral pleura, bronchi, thoracic part of trachea, left side of heart, esophagus, posterior mediastinum	tracheobronchial nodes may be divided into five groups: paratracheal (tracheal), superior tracheobronchial, inferior tracheobronchial, bronchopulmonary (hilar), pulmonary
tracheobronchial nodes, inferior	inferior to tracheal bifurcation	bronchopulmonary nodes, left side inferior tracheobronchial nodes drain into right inferior tracheobronchial nodes	right superior tracheobronchial nodes	lower lobes of the lungs; middle mediastinum; posterior mediastinum	left inferior tracheobronchial nodes drain to the right side
tracheobronchial nodes, superior	superolateral to the tracheal bifurcation	bronchopulmonary (hilar) nodes	paratracheal (tracheal) nodes	lungs, middle mediastinum, posterior mediastinum	inferior tracheobronchial nodes drain lymph from the lower lobe of the left lung to the right superior tracheobronchial nodes

 

 

 

 

 

THE PUDENDAL NERVE AND INTERNAL PUDENDAL VESSELS PASS THROUGH THE PUDENDAL [ ALCOCK’S ] CANAL.

THIS CANAL IS FORMED BY THE FASCIA OF THE OBTURATOR INTERNUS MUSCLE ON THE LATERAL WALL OF THE ISCHIORECTAL FOSSA.

The Pudendal Nerve

This nerve arises from the sacral plexus within the pelvis, it must go around the pelvic floor to reach the ischioanal fossa. In the pelvis it runs on piriformis and then passes laterally through the greater sciatic foramen to enter the gluteal region.

Here it lies inferior to piriformis as does the sciatic nerve, the inferior gluteal neurovascular bundle and the nerve to quadratus femoris.

The pudendal nerve curls around the spine of the ischium lying superficial to the sacrospinous ligament and then passes into the lessor sciatic notch to enter the ischioanal fossa.
This nerve then divides into the inferior rectal, the perineal and the dorsal nerve of the penis (clitoris).

The inferior rectal nerve supplies the external anal sphincter and perianal skin.
The perineal nerve supplies ischiocavernosus, bulbospongiosus, superficial and deep transverse perinei, sphincter urethrae and skin over the posterior two-thirds of the scrotum (labium majorum) and the mucous membrane of the urethra (labia minoria).
The dorsal nerve of the penis (clitoris) supplies most of the skin of the penis (clitoris) a patch of skin on the dorsum of the penis is innervated by the ilioinguinal nerve.    The nerve supply to the perineum originates from three main sources:

1. The Genito-femoral Nerve (L1,L2).

2. The pudendal nerve arises from the anterior rami of the second to fourth sacral roots. These form a trunk before leaving the pelvis via the greater sciatic foramen. It passes immediately behind the ischial spine and swings forward to enter the perineum via the lesser sciatic foramen. The nerve passes through the ischiorectal fossa where it gives off its terminal branches. The inferior rectal nerve innervates the external anal sphincter and the perianal skin. The perineal nerve innervates the sphincter urethrae and other muscles of the anterior compartment via a deep branch, and the skin of the perineum poterior to the clitoris via its superficial branch. The dorsal nerve of the clitoris supplies the skin surrounding this structure.

3. The perineal branch of the posterior femoral nerve.

On the lateral wall of the ischioanal fossa, identify the pudendal (Alcock's) canal and its contents. This compartment is located in the inferior border of the obturator internus fascia. It extends from the ischial spine to the posterior edge of the ischiopubic ramus.

Open the canal and identify the internal pudendal vessels and the three branches of the pudendal nerve:

• inferior rectal nerve
• dorsal nerve of the clitoris
• perineal nerve

The latter divides into superficial and deep branches.

 

   

NERVES OF THE PERINEUM

Pudendal nerve (S2, 3, 4) has 3 main branches:

Inferior rectal nerve is motor to external voluntary anal sphincters and sensory to skin around anus. It also supplies the levator ani.

Perineal nerve has Superficial sensory branches to the scrotum/labia majora (posterior scrotal/labial nerves) and Deep motor branches to muscles in the superficial and deep spaces.

Dorsal nerve of clitoris/penis is sensory to skin on the penis or clitoris.

Perineal branch of posterior cutaneous nerve of the thigh is sensory to labia majora and scrotum laterally.

Ilioinguinal nerve (L1) is sensory to the anterior labia majora or scrotum (Anterior labial/scrotal nerves).

Genitofemoral nerve (L1, 2)

Genital branch is motor to cremaster muscle and sensory to a small part of the scrotum or labia and adjacent thigh. (Femoral branch is sensory to skin superficial to the femoral triangle.)

 

 

VESSELS OF THE PERINEUM

Internal pudendal artery is a branch of the internal iliac artery that enters the gluteal region through the greater sciatic foramen. It then enters the perineum after crossing posterior to the spine of the ischium through the lesser sciatic foramen. It lies in the pudendal (Alcock's) canal, a fascial tunnel on the medial aspect of the obturator internus muscle. Branches of the internal pudendal artery are:

Inferior rectal artery- supplies rectum, anal sphincter, and anus.
Transverse perineal artery.
Perineal artery- supplies structures in deep and superficial spaces. It gives off posterior labial/scrotal branches.
Deep artery to crura and corpora cavernosa.
Artery to bulb and corpus spongiosum.
Dorsal artery of the clitoris/penis.

Deep and superficial external pudendal arteries also supply the perineal region. They are branches of the femoral artery and are accompanied by veins of the same name which drain skin and superficial fascia to femoral or greater saphenous veins.

Venous drainage of the perineum mostly follows the course of the internal pudendal artery. One exception to this is the deep dorsal vein of the penis/clitoris which passes inferior to the pubic arch directly into the pelvis to empty into the prostatic venous plexus (male) or vesicular plexus (female).

Urogenital diaphragm is located in the urogenital triangle, inferior to the pelvic diaphragm. It is attached to the ischiopubic rami. It consists of two muscles and two layers of investing (deep) fascia:

Muscles:
    deep transverse perineus
    sphincter urethrae
Investing Fascia:
    superior fascia of the UG diaphragm
    inferior fascia of the UG diaphragm

There are two spaces in the perineum which are bounded by deep fascia; deep and superficial perineal spaces.

Deep space is the space between the inferior and superior fascia of the urogenital diaphragm. It contains:

• deep transverse perineal muscle (including sphincter urethrae)
• branches of internal pudendal vessels and pudendal nerves
• bulbourethral (Cowper's) glands in the male

Superficial space is the area between the external perineal fascia, which is another deep fascia of the perineum, and the inferior fascia of the urogenital diaphragm. It contains:

• crura and bulbs in both sexes
• ischiocavernosus and bulbospongiosus (also called bulbocavernosus) muscles
• superficial transverse perineus muscle
• branches of internal pudendal vessels and pudendal nerves
• greater vestibular (Bartholin's) glands in female
• ducts of bulbourethral glands (Cowper's) in the male

 

What are the boundaries of the perineum?

1. The boundaries of the perineum are 1) the symphysis pubis, 2) the inferior pubic rami, 3) the ischial rami, 4) the ischial tuberosities, 5) the sacrotuberous ligaments, and 6) the coccyx

What kind of muscle is the external anal sphincter - skeletal or smooth?

2. It is skeletal muscle.

How is the external anal sphincter innervated?

3. It is innervated by the perineal branch of the fourth sacral nerve and by the inferior rectal nerves. The cell bodies of the motoneurons which supply it are located in the ventral gray column of the midsacral spinal cord, especially S4.

From what artery does the inferior rectal artery arise?

4. Internal pudendal artery

What other arteries supply the rectum?

5. The middle and superior rectal arteries.

What is the venous drainage of the rectum?

6. The venous drainage follows the arteries. A plexus of veins surrounds the rectum and drains chiefly into the superior rectal vein, which is a tributary to the inferior mesenteric vein. The paired middle and inferior rectal veins drain into the internal iliac veins.

What are hemorrhoids? Distinguish between internal and external hemorrhoids.

7. Hemorrhoids are varicose dilations of veins in the rectal submucosal venous plexus. Internal hemorrhoids lie above the pectinate line and drain into the superior rectal vein. External hemorrhoids are below the pectinate line and drain into the inferior rectal veins.

What are the boundaries of the ischiorectal (ischioanal) fossa?

8. Medially--levator ani  Laterally--obturator internus   Posteriorly--gluteus maximus  and sacrotuberous ligament   Inferiorly--urogenital diaphragm and skin

How far anteriorly does the anterior recess of the ischiorectal (ischioanal) fossa reach?

9. To the body of the pubis.

What is the pudendal canal?

10. A passageway for the internal pudendal artery and vein and the pudendal nerve in the obturator internus fascia on the lateral wall of the ischiorectal fossa (spine to tuberosity of ischium).

Consider some of the structures that could be damaged by an incision to drain an abscess in the ischiorectal fossa.

11. The pudendal nerve and its branches, especially the inferior rectal, and the internal pudendal vessels pass from the pudendal canal into the fat of the ischiorectal fossa and could be damaged.  The external anal sphincter and the levator ani muscles also could be damaged

What does the inferior rectal nerve supply?

12. External anal sphincter muscle and skin adjacent to anus

What nerve supplies the levator ani?

13. Nerve to the levator ani on its superior surface direct from the sacral plexus (chiefly S4).

What nerves supply the scrotum?

14. Anterior scrotal nerves from the ilioinguinal nerve, posterior scrotal from the pudendal nerve; genital branch of genitofemoral supplies the cremaster muscle as well as the skin, and laterally the perineal branch of the posterior femoral cutaneous

Do the two ischiorectal (ischioanal) fossae communicate?

15. Yes. The two fossae communicate with each other posterior to the anal canal above a part of the external anal sphincter that extends backward to attach to the coccyx.  Here an abscess in one ischiorectal fossa may extend across to the other fossa.

Define each of the following terms:

a. arcuate line (of the rectus sheath)____line in posterior rectus sheath below which the sheath is composed only of transversalis fascia__

b. arcuate line (of the ilium)__the part of the pelvic brim formed by the ilium___________

b. median arcuate ligament___the border of the aortic hiatus between the two crura of the diaphragm__

c. medial arcuate ligament___origin of the diaphragm from the fascia of the psoas major muscle_

d. lateral arcuate ligament___origin of the diaphragm from the fascia of the quadratus lumborum muscle___

e. arcuate eminence__prominence on petrous ridge of temporal bone caused by anterior semicircular canal__

e. arcus tendineus__origin of levator ani muscle from fascia of obturator internus muscle__

f. left crus of the penis___proximal attached part of left corpus cavernosum penis_____

g. right crus of the diaphragm___portion of diaphragm that originates from right side of the bodies of upper lumbar vertebrae___

h. lateral crus of the superficial inguinal ring__lateral or inferior portion of external oblique aponeurosis bordering superficial inguinal ring___

i. deep inguinal ring__opening in anterior abdominal wall bordered by lower edge of transversus abdominis muscle, the inferior epigastric artery, and the inguinal ligament

Ø      The inferior vena cava is normally found on the __right___________side of the
abdominal aorta. The left renal vein is normally __ventral___________ to the aorta and
drains blood from the kidney, the __left suprarenal gland_, and the _left gonad___.

 

Match the adult structures in column A with their embryonic precursors in column B. The structures in column B may be used once, more than once, or not at all.

	A		B
	__C__adrenal medulla __B__Bowman's capsule __B__distal convoluted tubule __A__ductus deferens __G__epithelium of female urethra __G__epithelium of urinary bladder __F__major calyx __F__minor calyx __G__prostate gland __A__seminal vesicle __D__uterine tube		A. mesonephric duct B. metanephric mass C. neural crest D. paramesonephric duct E. pronephros F. ureteric bud G. urogenital sinus
A		B
__G__ligamentum arteriosum __A__ligamentum venosum __L__ligamentum teres hepatis __K__medial umbilical ligament __M__median umbilical ligament __H__internal carotid artery __B__external acoustic meatus __C__tympanic cavity __I__palatine tonsil __J__thymus __D__superior parathyroid gland		ductus venosus first branchial groove (cleft) first branchial pouch fourth branchial pouch left first aortic arch left fourth aortic arch left sixth aortic arch left third aortic arch second branchial pouch third branchial pouch umbilical artery umbilical vein urachus

 

Fat that is located within the renal fascia is called ___perirenal_________________ fat,
while fat that is external to the renal fascia is called ___pararenal___________________ fat.
The cavity within the kidney which contains major and minor calyces and part of the renal pelvis, as well as branches of the renal artery and tributaries to the renal vein is called the
___renal sinus_________________________.

 

The organ which lies directly ventral to the hilus of the right kidney is the
___2nd part of the duodenum____________________________. The organ which is directly
ventral to the hilus of the left kidney is the ___pancreas_________________________.

 

The pelvic brim is the boundary between the ___major pelvis__________________ and the
___minor pelvis________________________. The feature of the sacrum which forms part
of the pelvic brim is the __promontory_____________________. Muscles which line the walls
of the true pelvis are the __piriformis________________ and the __obturator internus____.
Muscles which form the pelvic diaphragm are the ___levator ani___________________
and the ____coccygeus________________________.

 

The three parts of the male urethra are the __prostatic urethra____________________, the
___membranous urethra_______________, and the ___spongy urethra_______________.

 

The three parts of the broad ligament are the ___mesosalpinx_____________________,
the __mesovarium_____________________, and the ____mesometrium_______________.

 

Lymph from the ovary and the testis drains to ___lumbar__________________nodes.
Lymph from the external genitalia drains to ___inguinal________________________nodes.