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Lab 11 Fetal Pig Dissection

Domestic Pig

Scientific Name: Sus scrofa
Family: "Suidae"
Order: "artiodactyla" (even-toed mammals)
gestation period - 4 months
fetal pigs in lab are between 80-100 days old with well developed organ systems

External Anatomy of the Fetal Pig

Eyelid, Pinna, External Nares, Vibrissae, Digits, Mammary Papilla, Umbilical Cord, Genital Papilla, Urogenital Opening, Scrotum, and Anus.

Eyelid

Pigs are born with closed lids.

Pinna

External ear flap. Gathers sound and directs it into the external auditory canal.

External Nares

External openings of the nose used for breathing and sense of smell. Pigs have well-developed sense of smell and use smell as their primary sensory modality when foraging.

Vibrissae

Long, stiff hairs on the head, commonly called whiskers. Function is touch.

Digits

Toes and hooves.

Mammary Papilla

5 to 6 pairs of these strucures presents in both sexes, but develop into the mammary glands in only females.

Umbillical Cord

Contains 2 umbillical arteries and 1 unbillical vein. Serves as a connection between fetus and fetal placenta. Vessels within cord are responsible for nutrient, gas, ans waste exchange between fetus and mother.

Genital Papilla

Female's external genitalia.

Urogenital Opening

Terminal end of male urogenital tract.

Scrotum

Sac of skin beneath the tail containing the male's testes.

Anus

Terminal opening of digestive tract.

Glands of the Head and Neck - Fetal Pig

Parotid gland, mandibular gland, sublingual gland, thymus gland, and thyroid gland.

Parotid Gland

Large salivary gland which lies posteriorly and ventrally to the masseter muscle.

Mandibular Gland

Small salivary gland. Has oval shape. Lies partially ventral to parotid gland and between the the parotid and angle of the jaw. Also called the "submaxillary gland".

Sublingual Gland

Salivary gland is narrow and flat. Lies beneath skin, medial to lower jaw, and alongside tongue.

Thymus Gland

Large, elongated endocrine gland. Lies beneath skin on each side of, and over, trachea. Also extends down into thoracic cavity - lies on dorsal surface of heart. Hormones from thymus gland stimulate early development of immune system.

Thyroid Gland

Small endocrine gland-darkly colored, has oval shape. Lies between 2 lobes of thymus gland, posterior to larynx and ventral to trachea. Remove 2 sternohyoid muscles to find.

Anatomy of the Mouth - Fetal Pig

Hard palate, soft palate, tongue, papillae of the tongue, pharynx, epiglottis and glottis.

Hard Palate

Ridged surface which forms the anterior portion of the roof of the mouth.

Soft Palate

Smooth surface which forms posterior portion of roof of mouth.

Tongue

Lies on floor of mouth, between lower jaws. Location of taste buds and aids in food manipulation.

Papillae of the Tongue

Small projections on tongue. Particularily large on anterior margins and base of tongue. Aid in manipulation of food.

Pharynx

Region of throat where oral and nasal cavities join.

Epiglottis

Flap of skin which covers the glottis. Serves to separate esophagus from trachea and prevent food or liquid from entering trachea.

Glottis

Hole that is opening of trachea covered by epiglottis.

Anatomy of Respiratory System - Fetal Pig

Trachea, larynx, lungs, hilus, and diaphragm.

Trachea

Tube commonly called the "windpipe". Extends from larynx in throat to lungs. Lined with cartilage rings which function to keep trachea open.

Larynx

Commonly called "voice box". Connects to glottis anteriorly and trachea posteiorly. Contains vocal cords which can be viewed by making longitudnal mid-dorsal incision, and opening the cartilage.

Lungs

Large organs that function in gas exchange. Lie on lateral sides of heart.

Hilus

Part of lung. Commonly known as "lung root" and is only part of lung attached to the body. Pulmonary vein, artery, and primary bronchi enter lung here.

Diagphragm

Skeletal muscle located between lungs and liver. Primary muscle responsible for breathing.

Digestive System - Fetal Pig

Majority located in abdominal cavity.

Anatomy of Digestive System - Fetal Pig

Esophagus, stomach, lesser omentum, greater omentum, pyloric sphincter muscle, gall bladder, common bile duct, liver, spleen, pancreas, duodenum, small intestine, mesentery, cecum, large intestine, colon, and rectum.

Esophagus

Tube connecting pharynx to stomach. Goes from throat, through diagphragm, into stomach.

Stomach

Digestive organ just posterior to liver.

Lesser Omentum

Sheet of connective tissue which attaches to and anchors inside convex curve of stomach.

Greater Omentum

Sheet of connective tissue which attaches to and anchors outside concave curve of stomach.

Pyloric Spincter Muscle

"Doughnut-like" smooth muscle, found at posterior end of stomach. Separates stomach from the duodenum.

Gall Bladder

Sac containing green bile, located underneath and attached to middle lobe of liver.

Common Bile Duct

Duct which transports bile to duodenum.

Liver

Largest gland in body, located between stomach and diagphragm. Reddish-brown in color.

Spleen

Organ is long, flat, finger-like projection to right of stomach. Functions to store blood. Dark red to purplish in color.

Pancreas

Has right and left lobe. Produces digestive enzymes. Right lobe of pancreas is beside pyloric sphincter, at base of stomach.

Duodenum

Anterior portion of small intestine, just posterior to stomach.

Small Intestine

Portion of digestive system between the stomach and large intestine.

Mesentery

Sheet of connective tissue attached to intestines.

Cecum

Finger-like projection of large intestine at junction of large and small intestines.

Large Intestine

Intestines posterior to cecum. Larger in diameter than the small intestines.

Colon

Most posterior portion of large intestines. Desends along and ventral to vertebral column.

Rectum

Muscular region at base of descending colon just anterior to anus.

Circulatory System - Fetal Pig

Network of blood vessels throughout body.

Veins of Fetal Pigs

Cranial vena cava, brachiocephalic veins, internal jugular vein, external jugular veins, cephalic veins, subclavian veins, axillary veins, subscapular veins, caudal vena cava, hepatic portal vein, umbillical vein, renal veins, common iliac veins, internal iliac veins, external iliac veins, femoral veins, and deep femoral veins.

Cranial Vena Cava

Large vein carrying blood from head, neck and forelimbs to right atrium.

Brachiocephalic Veins

Carry blood from the cephalic, subclavian, and jugular veins to the cranial vena cava.

Internal Jugular Vein

1st set of vessels to emerge from cranial vena cava, medially. Carry blood from head to brachioencephalic veins. Located on either side of trachea.

External Jugular Veins

2nd set of vessels to emerge from cranial vena cava, medially. Carry blood from head to brachioencephalic veins.

Cephalic Veins

3rd vessels to emerge from cranial vena cava, medially. Carry blood from forelimb to brachioencephalic veins.

Subclavian Veins

4th set of vessels to emerge from cranial vena cava, medially. Carry blood from the subscapular veins and axillary veins to brachioencephalic veins.

Axillary Veins

Carry blood from forelimbs and join with subscapular veins to form subclavian vein.

Subscapular Veins

Carry blood from region of armpit and join with axillary vein to form subclavian vein.

Caudal Vena Cava

Large vein carrying blood from posterior portion of body to right atrium.

Hepatic Portal Vein

Large vein (may be yellow). Located between stomach and liver. Carries blood from stomach, spleen, pancreas, and intestines to liver.

Umbillical Vein

Carries blood containing oxygen and nutrients from placenta to fetus.

Renal Veins

Carry blood from kidneys to caudal vena cava.

Common Iliac Veins

Carry blood from external and interal iliac veins to caudal vena cava.

Internal Iliac Veins

Carry blood from pelvis to common iliac veins.

External Iliac Veins

Veins carry blood from femoral and deep femoral veins to common iliac veins.

Femoral Veins

Carry blood from the thigh and lower hind to external iliac veins.

Deep Femoral Veins

Carry blood from thigh to external iliac veins.

Arteries of Fetal Pig

Aortic Arch, Brachiocephalic Trunk, Left Subclavian Artery, Carotid Trunk, Common Carotid Arteries, External Carotid Artery, Internal Carotid Arteries, Right Subclavian Artery, Axillary Arteries, Brachial Artery, Aorta, Celiac Trunk, Cranial Mesenteric Artery, Renal Arteries, Caudal Mesenteric Artery, Umbillical Arteries, External Iliac Arteries, Internal Iliac Arteries, Femoral Arteries, Deep Femoral Ateries.

Aortic Arch

Artery that leaves left ventricle and gives rise to the brachiocephalic trunk, left subclavian artery, and aorta.

Brachioencephalic Trunk

1st large artery arising from aortic arch. Carries oxygenated blood to neck, head, and right forelimb.

Left Subclavian Artery

2nd large artery arisig from aortic arch. Carries blood or left forelimb.

Carotid Trunk

1st vessel to arise from right brachiocephalic trunk, medially. Carries blood anteriorly towards neck and head.

Common Carotid Arteries

Carotid trunk splits into right and left common carotid arteries.

External Carotid Artery

Arteries are medial branches of common carotid arteries. Carry blood to area around masseter muscle and chin.

Internal Caroltid Arteries

Laternal branches of common carotid arteries. Carry blood to brain.

Right Subclavian Artery

2nd arteries to arise from right brachioencephalic trunk. Supplies blood to cervical vertebrae and right forelimb.

Axillary Arteries

Continuation of subclavian arteries. Carry blood to armpit, shoulder, and forelimb.

Brachial Artery

Arise from axillary arteries and carry blood into the forelimbs.

Aorta

Large vessel lying on mid-dorsal wall, length of abdominal cavity. Carries blood to entire posterior portion of body.

Celiac Trunk

1st artery to branch off aorta, posterior to diaphragm. Carries blood to stomach, pancreas, and spleen.

Cranial Mesenteric Artery

2nd artery to branch off aorta, posterior to diaphragm. Carries blood to most of small intestine.

Renal Arteries

2 large arteries branch off aorta and carry blood to kidneys.

Caudal Mesenteric Artery

Branches off ventral surface of aorta before it splits into umbillical arteries. Carries blood to large interstine and colon.

Umbillical Arteries

Terminal end of aorta splits into these 2 arteries. Enter umbillical cord and carry blood to placenta.

External Iliac Arteries

Branch off aorta immediately anterior to umbillical arteries. Carry blood to thighs and hind limbs.

Internal Iliac Arteries

Branch dorsally off aorta, immediately to umbilical arteries. Carry blood to pelvic region.

Femoral Arteries

1 of 2 branches of external iliac arteries. Carry blood to thigh and lower hind limb.

Deep Femoral Arteries

1of 2 branches of external arteries. Carry blood to thigh.

Anatomy of the Urinary System - Fetal Pig

Kidney, ureter, urinary bladder, and urethra.

Kidney

Large, kidney-bean-shaped organs located on posterior dorsal wall of abdominal cavity. Lie beneath layer of connective tissue on either side of dorsal aorta. Produce urine.

Ureter

Paired tubes which join kidneys and urinary bladder. Carry urine to bladder.

Urinary Bladder

Large sac located between 2 umbilical arteries. Temporary storage for urine.

Urethra

Tube transports urine to outside when bladder is emptied. Short in females, just ventral to anus. Longer in males ends at urogenital opening. Also functions to conduct semen in males.

Male Reproductive System - Fetal Pig

Scrotum, Testes, Epididymis, Ductus Deferens (vas deferens), Inguinal Canal, Seimnal Vesicles, Prostate Gland, and Penis.

Scrotum

External pouch or sac located just ventrally to tail and anus. Contains testes.

Testes

Small, bean-shaped male reporductive organs contained in scrotum. Produce sperm and testosterone.

Epididymis

These are located superficially on posterior margin of testes. Long and coiled tubule which coils to use very little space. Functions in sperm storage and maturation.

Ductus Deferens (vas deferens)

Ducts which connect epididymis to urethra. Turn over the uterters to join urethra just anterior to where ureters enter the bladder. Function is to transfer sperm from epididymis to urethra during ejaculation.

Inguinal Canal

Passageways through abdominal wall in groin of males through which ductus deferens and blood vessels pass to testes.

Seminal Vesicles

Small glands located near junction of ductus deferens and urethra. Produce some of seminal fluid.

Prostate Gland

Small gland which surrounds junction of ductus deferens and urethra. Produces some seminal fluid. To find, dissect between seminal vessicles.

Bulbourethral glands

Pair of glands near base of penis in pelvic canal on either side of urethra. Produce some of the seminal fluid. Also called "Cowper's glands".

Penis

Male copulatory organ located ventrally on exterior abdomincal wall, just posterior or umbillical cord.

Female Reproductive System - Fetal Pig

Ovaries, Uterine Tubes (Fallopian Tubes), Uterine Horns, Uterine Body, Vagina, and Genital Papilla.

Ovaries

Female reproductive organs. Small, bean-shaped located in dorsal abdominal wall, just posterior to kidneys. Produce eggs and hormones like estrogen and progesterone.

Uterine Tubes (Fallopian Tubes)

Small ducts found between ovaries and uterine horns. Passageways through which eggs reach uterus. Fertilization occurs in uterine tubes.

Uterine Horns

Wider tubes located at end of uterine tubes and connected to uterine body. Embryos develop within these tubes.

Uterine Body

Single, wider tube formed by union of 2 uterine horns. Cervix is at posterior end.

Vagina

Mosts posterior tube of female reproductive tract. Is female copulatory organ and receives male penis during copulation.

Genital Papilla

Female's external genetalia located directly below the anus.

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