All Answers

• What is the kneecap called?

  The kneecap is called the patella. Gray's Anatomy (1918) describes it as a small, flat, triangular sesamoid bone embedded in the tendon of the quadriceps.

• What is the thigh bone called?

  The thigh bone is called the femur. Gray's Anatomy (1918) describes it as the longest, strongest, and heaviest bone in the human body.

• What is the collarbone called?

  The collarbone is called the clavicle. Gray's Anatomy (1918) describes it as a slender, doubly-curved long bone that lies almost horizontally.

• What is the shoulder blade called?

  The shoulder blade is called the scapula. Gray's Anatomy (1918) describes it as a large, flat, triangular bone.

• What is the breastbone called?

  The breastbone is called the sternum. Gray's Anatomy (1918) describes it as a flat, elongated bone in three parts: manubrium, body, and xiphoid process.

• What is the upper arm bone called?

  The upper arm bone is called the humerus. Gray's Anatomy (1918) describes it as the single long bone of the upper arm.

• What is the shin bone called?

  The shin bone is called the tibia. Gray's Anatomy (1918) describes it as the larger and stronger of the two bones of the leg.

• What is the calf bone called?

  The outer leg bone is called the fibula. Gray's Anatomy (1918) describes it as the slender, non-weight-bearing bone of the leg, lateral to the tibia.

• What is the skull called?

  The skull is called the cranium. Gray's Anatomy (1918) describes it as the bony framework of the head, made up of 22 bones. Older texts sometimes use 'cranium' for the whole skull; modern texts often reserve it for just the braincase.

• What is the lower jaw called?

  The lower jaw is called the mandible. Gray's Anatomy (1918) describes it as the largest and strongest bone of the face.

• What is the upper jaw called?

  The upper jaw is called the maxilla. Gray's Anatomy (1918) describes it as a pair of bones that together form the upper jaw.

• What is the hip bone called?

  The hip bone is called the pelvis (os coxae). Gray's Anatomy (1918) describes it as each hip bone is a large, irregular bone formed by the fusion of three parts: ilium, ischium, and pubis. 'Pelvis' can mean either the whole bony ring or, loosely, the hip bone; modern texts usually call the single bone the 'hip bone' or 'os coxae'.

• What is the tailbone called?

  The tailbone is called the coccyx. Gray's Anatomy (1918) describes it as a small, triangular bone formed by the fusion of the last three to five vertebrae.

• What is the sacrum?

  It is called the sacrum. Gray's Anatomy (1918) describes it as a large, triangular bone made from the fusion of five sacral vertebrae.

• What is the forearm bone on the thumb side called?

  The forearm bone on the thumb side is called the radius. Gray's Anatomy (1918) describes it as one of the two bones of the forearm, on the thumb side.

• What is the forearm bone on the little finger side called?

  The forearm bone on the little finger side is called the ulna. Gray's Anatomy (1918) describes it as the longer of the two forearm bones, on the little-finger side.

• What are the wrist bones called?

  The wrist bones is called the carpals. Gray's Anatomy (1918) describes it as a group of eight small bones arranged in two rows of four.

• What are the hand bones called?

  The long bones of the palm is called the metacarpals. Gray's Anatomy (1918) describes it as five long bones forming the framework of the palm.

• What are finger bones called?

  The finger and toe bones is called the phalanges. Gray's Anatomy (1918) describes it as the bones of the fingers and toes.

• What are the ankle bones called?

  The ankle bones is called the tarsals. Gray's Anatomy (1918) describes it as seven short bones forming the back half of the foot.

• What are the foot bones called?

  The long bones of the foot is called the metatarsals. Gray's Anatomy (1918) describes it as five long bones forming the middle of the foot.

• What is the backbone called?

  The backbone is called the vertebral column (spine). Gray's Anatomy (1918) describes it as a flexible column of 33 bones (vertebrae) stacked one on top of the other.

• What are the ribs called?

  It is called the ribs (costae). Gray's Anatomy (1918) describes it as twelve pairs of flat, curved bones that form the walls of the chest.

• What is the first vertebra called?

  The top vertebra of the neck is called the atlas. Gray's Anatomy (1918) describes it as the top vertebra of the spine, on which the skull rests.

• What is the second vertebra called?

  The second vertebra of the neck is called the axis. Gray's Anatomy (1918) describes it as the second cervical vertebra.

• What is the hyoid bone?

  The hyoid bone is called the hyoid. Gray's Anatomy (1918) describes it as a small, U-shaped bone.

• What is the cheekbone called?

  The cheekbone is called the zygomatic bone. Gray's Anatomy (1918) describes it as a small, roughly quadrangular bone.

• What is the heel bone called?

  The heel bone is called the calcaneus. Gray's Anatomy (1918) describes it as the largest of the tarsal bones.

• What is the ankle bone that meets the leg called?

  The ankle bone that meets the leg is called the talus. Gray's Anatomy (1918) describes it as an irregular tarsal bone with a dome-shaped upper surface.

• What is the occipital bone?

  The occipital bone is called the occipital bone. Gray's Anatomy (1918) describes it as a single trapezoid-shaped bone that forms the back and lower part of the skull.

• What are the parietal bones?

  The parietal bones is called the parietal bones. Gray's Anatomy (1918) describes it as a pair of roughly rectangular, curved bones.

• What is the frontal bone?

  The frontal bone is called the frontal bone. Gray's Anatomy (1918) describes it as a single flat bone that forms the forehead.

• What are the temporal bones?

  The temporal bones is called the temporal bones. Gray's Anatomy (1918) describes it as a pair of irregular bones on each side of the skull.

• What is the ischium?

  The the sit bone is called the ischium. Gray's Anatomy (1918) describes it as the lower and back part of the hip bone.

• What is the ilium?

  The large upper part of the hip bone is called the ilium. Gray's Anatomy (1918) describes it as the largest of the three parts of the hip bone.

• What is the pubis?

  The front part of the hip bone is called the pubis. Gray's Anatomy (1918) describes it as the front part of the hip bone.

• What is the biceps called?

  It is called the biceps brachii. Gray's Anatomy (1918) describes it as a two-headed muscle on the front of the upper arm.

• What is the triceps called?

  It is called the triceps brachii. Gray's Anatomy (1918) describes it as a three-headed muscle on the back of the upper arm.

• What is the deltoid?

  The shoulder cap muscle is called the deltoid. Gray's Anatomy (1918) describes it as a thick, triangular muscle that caps the shoulder.

• What is the chest muscle called?

  The chest muscle is called the pectoralis major. Gray's Anatomy (1918) describes it as a large, fan-shaped muscle covering the front of the upper chest.

• What are the lats called?

  The lats is called the latissimus dorsi. Gray's Anatomy (1918) describes it as a broad, flat, triangular muscle of the back.

• What is the trapezius?

  It is called the trapezius. Gray's Anatomy (1918) describes it as a large, kite-shaped superficial muscle of the upper back and neck.

• What are the quadriceps called?

  The front thigh muscles is called the quadriceps femoris. Gray's Anatomy (1918) describes it as a group of four muscles on the front of the thigh: rectus femoris, vastus lateralis, vastus medialis, and vastus intermedius.

• What are the hamstrings called?

  The back thigh muscles is called the hamstrings (biceps femoris, semitendinosus, semimembranosus). Gray's Anatomy (1918) describes it as a group of three muscles on the back of the thigh.

• What is the calf muscle called?

  The calf muscle is called the gastrocnemius. Gray's Anatomy (1918) describes it as a large, superficial, two-headed muscle that forms the bulk of the calf.

• What is the soleus?

  The deep calf muscle is called the soleus. Gray's Anatomy (1918) describes it as a broad, flat muscle lying beneath the gastrocnemius.

• What is the butt muscle called?

  The butt muscle is called the gluteus maximus. Gray's Anatomy (1918) describes it as the largest and most superficial of the three gluteal muscles.

• What is the six-pack muscle called?

  The the six-pack muscle is called the rectus abdominis. Gray's Anatomy (1918) describes it as a long, flat muscle running down the front of the abdomen.

• What is the sartorius?

  It is called the sartorius. Gray's Anatomy (1918) describes it as a long, strap-like muscle — the longest muscle in the human body.

• What is the jaw muscle called?

  The jaw muscle is called the masseter. Gray's Anatomy (1918) describes it as a thick, short muscle on the side of the face.

• What are the ovaries?

  It is called the ovaries. Gray's Anatomy (1918) describes it as a pair of almond-shaped organs.

• What is the neck muscle called?

  The long neck muscle is called the sternocleidomastoid. Gray's Anatomy (1918) describes it as a long, strap-like muscle on each side of the neck.

• What is the eye muscle that closes the lid called?

  The muscle that closes the eyelid is called the orbicularis oculi. Gray's Anatomy (1918) describes it as a flat, circular sphincter muscle surrounding the eye.

• What is the lip muscle called?

  The muscle around the mouth is called the orbicularis oris. Gray's Anatomy (1918) describes it as a complex sphincter-like muscle surrounding the mouth.

• What are the intercostal muscles?

  The muscles between the ribs is called the intercostal muscles. Gray's Anatomy (1918) describes it as two layers of thin muscles — external and internal intercostals — filling the spaces between adjacent ribs.

• What are the obliques?

  The side abdominal muscles is called the external and internal oblique muscles. Gray's Anatomy (1918) describes it as two broad, flat muscles that make up the sides of the abdominal wall.

• What is the brachialis?

  It is called the brachialis. Gray's Anatomy (1918) describes it as a powerful elbow flexor lying beneath the biceps.

• What is the tongue?

  The the tongue is called the tongue (lingua). Gray's Anatomy (1918) describes it as a muscular organ made of two sets of muscles: intrinsic (which change its shape) and extrinsic (which move it in the mouth).

• What is the brachioradialis?

  It is called the brachioradialis. Gray's Anatomy (1918) describes it as a superficial muscle of the forearm.

• What is the diaphragm?

  The the diaphragm is called the diaphragm. Gray's Anatomy (1918) describes it as a dome-shaped sheet of muscle and tendon.

• What is the tensor fasciae latae?

  The tensor fasciae latae is called the tensor fasciae latae. Gray's Anatomy (1918) describes it as a short muscle on the outer side of the hip.

• What is the main artery called?

  The main artery is called the aorta. Gray's Anatomy (1918) describes it as the largest artery in the body.

• What is the superior vena cava?

  The large upper-body vein is called the superior vena cava. Gray's Anatomy (1918) describes it as a large vein that drains blood from the head, neck, arms, and upper chest.

• What is the inferior vena cava?

  The large lower-body vein is called the inferior vena cava. Gray's Anatomy (1918) describes it as the largest vein in the body.

• What is the pulmonary artery?

  The pulmonary artery is called the pulmonary artery (pulmonary trunk). Gray's Anatomy (1918) describes it as a short, wide artery that carries deoxygenated blood from the heart to the lungs.

• What are the pulmonary veins?

  The pulmonary veins is called the pulmonary veins. Gray's Anatomy (1918) describes it as four veins — two from each lung — that carry oxygenated blood back to the heart.

• What are the coronary arteries?

  The coronary arteries is called the coronary arteries. Gray's Anatomy (1918) describes it as the arteries that supply the heart muscle itself.

• What is the left ventricle?

  The left ventricle is called the left ventricle. Gray's Anatomy (1918) describes it as the lower left chamber of the heart.

• What is the right ventricle?

  The right ventricle is called the right ventricle. Gray's Anatomy (1918) describes it as the lower right chamber of the heart.

• What is the left atrium?

  The left atrium is called the left atrium. Gray's Anatomy (1918) describes it as the upper left chamber of the heart.

• What is the right atrium?

  The right atrium is called the right atrium. Gray's Anatomy (1918) describes it as the upper right chamber of the heart.

• What is the mitral valve?

  The mitral valve is called the mitral valve (bicuspid valve). Gray's Anatomy (1918) describes it as a two-leaflet valve between the left atrium and left ventricle. Also called the bicuspid valve because it has two cusps.

• What is the tricuspid valve?

  The tricuspid valve is called the tricuspid valve. Gray's Anatomy (1918) describes it as a three-leaflet valve between the right atrium and right ventricle.

• What is the aortic valve?

  The aortic valve is called the aortic valve. Gray's Anatomy (1918) describes it as a three-cusp valve at the base of the aorta.

• What is the pulmonary valve?

  The pulmonary valve is called the pulmonary valve. Gray's Anatomy (1918) describes it as a three-cusp valve at the base of the pulmonary trunk.

• What is the carotid artery?

  The carotid artery is called the common carotid artery. Gray's Anatomy (1918) describes it as a large artery on each side of the neck.

• What is the jugular vein?

  The jugular vein is called the internal jugular vein. Gray's Anatomy (1918) describes it as a large vein that drains blood from the brain, face, and neck.

• What is the femoral artery?

  The femoral artery is called the femoral artery. Gray's Anatomy (1918) describes it as the main artery of the thigh.

• What is the brachial artery?

  The brachial artery is called the brachial artery. Gray's Anatomy (1918) describes it as the main artery of the upper arm.

• What are capillaries?

  The the smallest blood vessels is called the capillaries. Gray's Anatomy (1918) describes it as the smallest blood vessels in the body.

• What is the septum of the heart?

  The wall between the heart chambers is called the septum of the heart. Gray's Anatomy (1918) describes it as a muscular wall that divides the heart into left and right sides.

• What is the main part of the brain called?

  The the largest part of the brain is called the cerebrum. Gray's Anatomy (1918) describes it as the largest part of the brain.

• What is the cerebellum?

  The the 'little brain' is called the cerebellum. Gray's Anatomy (1918) describes it as a cauliflower-shaped part of the brain.

• What is the brainstem?

  The the brainstem is called the brainstem. Gray's Anatomy (1918) describes it as the stalk of the brain that connects the cerebrum and cerebellum to the spinal cord.

• What is the medulla oblongata?

  The medulla oblongata is called the medulla oblongata. Gray's Anatomy (1918) describes it as the lowest part of the brainstem.

• What is the pons?

  It is called the pons. Gray's Anatomy (1918) describes it as a rounded bulge on the front of the brainstem.

• What is the thalamus?

  It is called the thalamus. Gray's Anatomy (1918) describes it as a pair of egg-shaped masses of gray matter deep within the cerebrum.

• What is the hypothalamus?

  It is called the hypothalamus. Gray's Anatomy (1918) describes it as a small region of the brain just below the thalamus.

• What is the corpus callosum?

  The corpus callosum is called the corpus callosum. Gray's Anatomy (1918) describes it as a broad band of nerve fibers.

• What is the hippocampus?

  It is called the hippocampus. Gray's Anatomy (1918) describes it as a curved, seahorse-shaped structure of gray matter.

• What is the amygdala?

  It is called the amygdala. Gray's Anatomy (1918) describes it as an almond-shaped cluster of nerve cell bodies.

• What is the spinal cord?

  The the spinal cord is called the spinal cord. Gray's Anatomy (1918) describes it as a long, cylindrical bundle of nerve fibers.

• What is the sciatic nerve?

  The sciatic nerve is called the sciatic nerve. Gray's Anatomy (1918) describes it as the largest nerve in the body.

• What is the vagus nerve?

  The vagus nerve is called the vagus nerve (tenth cranial nerve). Gray's Anatomy (1918) describes it as the tenth cranial nerve.

• What is the optic nerve?

  The optic nerve is called the optic nerve (second cranial nerve). Gray's Anatomy (1918) describes it as the second cranial nerve.

• What is the facial nerve?

  The facial nerve is called the facial nerve (seventh cranial nerve). Gray's Anatomy (1918) describes it as the seventh cranial nerve.

• What is the trigeminal nerve?

  The trigeminal nerve is called the trigeminal nerve (fifth cranial nerve). Gray's Anatomy (1918) describes it as the fifth cranial nerve.

• What are the cranial nerves?

  The the cranial nerves is called the cranial nerves. Gray's Anatomy (1918) describes it as twelve pairs of nerves that emerge directly from the brain and brainstem.

• What are the meninges?

  The the meninges is called the meninges. Gray's Anatomy (1918) describes it as three connective-tissue membranes that surround the brain and spinal cord.

• What is gray matter?

  The gray matter is called the gray matter. Gray's Anatomy (1918) describes it as the nervous tissue made mostly of nerve-cell bodies and their short processes.

• What is white matter?

  The white matter is called the white matter. Gray's Anatomy (1918) describes it as the nervous tissue made mostly of myelinated nerve fibers.

• What is the dura mater?

  The dura mater is called the dura mater. Gray's Anatomy (1918) describes it as the tough, fibrous outermost of the three meninges.

• What is the pituitary gland?

  The master gland is called the pituitary gland (hypophysis). Gray's Anatomy (1918) describes it as a small, pea-sized gland.

• What is the food pipe called?

  The food pipe is called the esophagus. Gray's Anatomy (1918) describes it as a muscular tube about 25 cm long.

• What is the stomach?

  The the stomach is called the stomach. Gray's Anatomy (1918) describes it as a muscular, sac-like organ.

• What is the small intestine?

  The small intestine is called the small intestine. Gray's Anatomy (1918) describes it as the longest part of the digestive tract, about 6 m long.

• What is the large intestine?

  The large intestine is called the large intestine (colon). Gray's Anatomy (1918) describes it as the last major part of the digestive tract, about 1.5 m long.

• What is the colon?

  The the colon is called the colon. Gray's Anatomy (1918) describes it as the main portion of the large intestine.

• What is the duodenum?

  It is called the duodenum. Gray's Anatomy (1918) describes it as the first and shortest part of the small intestine, about 25 cm long.

• What is the jejunum?

  It is called the jejunum. Gray's Anatomy (1918) describes it as the middle segment of the small intestine.

• What is the ileum?

  It is called the ileum. Gray's Anatomy (1918) describes it as the final segment of the small intestine.

• What is the cecum?

  It is called the cecum. Gray's Anatomy (1918) describes it as a blind pouch at the start of the large intestine.

• What is the appendix?

  The appendix is called the vermiform appendix. Gray's Anatomy (1918) describes it as a narrow, worm-shaped tube.

• What is the rectum?

  It is called the rectum. Gray's Anatomy (1918) describes it as the last straight segment of the large intestine, about 12 cm long.

• What is the anus?

  It is called the anus. Gray's Anatomy (1918) describes it as the external opening of the digestive tract.

• What is the liver?

  The the liver is called the liver. Gray's Anatomy (1918) describes it as the largest gland in the body.

• What is the gallbladder?

  The the gallbladder is called the gallbladder. Gray's Anatomy (1918) describes it as a small, pear-shaped sac.

• What is the pancreas?

  The the pancreas is called the pancreas. Gray's Anatomy (1918) describes it as a long, tapered gland with both digestive and endocrine functions.

• What are the salivary glands?

  The salivary glands is called the salivary glands. Gray's Anatomy (1918) describes it as three pairs of large glands — parotid, submandibular, and sublingual — plus many small ones.

• What are the teeth?

  The the teeth is called the teeth (dentes). Gray's Anatomy (1918) describes it as hard, calcified structures embedded in the jaws.

• What is the pharynx?

  The the throat is called the pharynx. Gray's Anatomy (1918) describes it as a muscular tube shared by the digestive and respiratory tracts.

• What is the bile duct?

  The bile duct is called the common bile duct. Gray's Anatomy (1918) describes it as a short tube that carries bile to the duodenum.

• What is peristalsis?

  It is called the peristalsis. Gray's Anatomy (1918) describes it as wave-like muscular contractions.

• What is the windpipe called?

  The windpipe is called the trachea. Gray's Anatomy (1918) describes it as a tube about 10-12 cm long and 2 cm wide.

• What are the testes?

  The testicles is called the testes. Gray's Anatomy (1918) describes it as a pair of oval organs.

• What are the bronchi?

  It is called the bronchi. Gray's Anatomy (1918) describes it as the two main branches of the trachea.

• What are bronchioles?

  It is called the bronchioles. Gray's Anatomy (1918) describes it as the smallest air-conducting tubes of the lung.

• What are alveoli?

  It is called the alveoli. Gray's Anatomy (1918) describes it as tiny air sacs at the end of the smallest airways.

• What are the lungs?

  The the lungs is called the lungs. Gray's Anatomy (1918) describes it as a pair of spongy, cone-shaped organs.

• What is the pleura?

  The the pleura is called the pleura. Gray's Anatomy (1918) describes it as a thin, double-layered membrane surrounding each lung.

• What is the diaphragm (in breathing)?

  The the diaphragm is called the diaphragm. Gray's Anatomy (1918) describes it as a dome-shaped sheet of muscle and tendon.

• What is the voice box called?

  The voice box is called the larynx. Gray's Anatomy (1918) describes it as a short, cartilage-framed tube at the top of the trachea.

• What are vocal cords?

  The vocal cords is called the vocal cords (vocal folds). Gray's Anatomy (1918) describes it as two folds of mucous membrane stretched across the larynx.

• What is the epiglottis?

  It is called the epiglottis. Gray's Anatomy (1918) describes it as a leaf-shaped flap of cartilage.

• What is the nasal cavity?

  The nasal cavity is called the nasal cavity. Gray's Anatomy (1918) describes it as the large air-filled space behind the nose.

• What are the nostrils called?

  The the nostrils is called the external nares. Gray's Anatomy (1918) describes it as the two external openings of the nose.

• What is the knee joint?

  The the knee joint is called the knee joint. Gray's Anatomy (1918) describes it as the largest and one of the most complex joints in the body.

• What is the hip joint?

  The the hip joint is called the hip joint. Gray's Anatomy (1918) describes it as a ball-and-socket synovial joint.

• What is the shoulder joint?

  The the shoulder joint is called the glenohumeral joint. Gray's Anatomy (1918) describes it as a ball-and-socket synovial joint.

• What is the elbow joint?

  The the elbow joint is called the elbow joint. Gray's Anatomy (1918) describes it as a hinge-type synovial joint.

• What is the ankle joint?

  The the ankle joint is called the ankle joint. Gray's Anatomy (1918) describes it as a hinge-type synovial joint.

• What is cartilage?

  It is called the cartilage. Gray's Anatomy (1918) describes it as a firm but flexible connective tissue.

• What is synovial fluid?

  The joint fluid is called the synovial fluid. Gray's Anatomy (1918) describes it as a viscous, egg-white-like fluid.

• What is the ACL?

  The ACL is called the anterior cruciate ligament. Gray's Anatomy (1918) describes it as one of two ligaments that cross inside the knee. Cruciate ligaments were named in older texts by their attachments; modern usage keeps 'anterior' and 'posterior' for the tibial attachment.

• What is the rotator cuff?

  The rotator cuff is called the rotator cuff. Gray's Anatomy (1918) describes it as a group of four muscles and their tendons — supraspinatus, infraspinatus, teres minor, and subscapularis.

• What is the Achilles tendon?

  The Achilles tendon is called the Achilles tendon (tendo calcaneus). Gray's Anatomy (1918) describes it as the thickest and strongest tendon in the body.

• What is the meniscus?

  It is called the meniscus of the knee. Gray's Anatomy (1918) describes it as a pair of C-shaped pads of fibrocartilage in the knee.

• What are the kidneys?

  The the kidneys is called the kidneys. Gray's Anatomy (1918) describes it as a pair of bean-shaped organs.

• What is the bladder?

  The the bladder is called the urinary bladder. Gray's Anatomy (1918) describes it as a hollow, muscular sac.

• What are the ureters?

  It is called the ureters. Gray's Anatomy (1918) describes it as a pair of narrow, muscular tubes about 25-30 cm long.

• What is the urethra?

  It is called the urethra. Gray's Anatomy (1918) describes it as a tube that carries urine from the bladder to outside the body.

• What is the spleen?

  The the spleen is called the spleen. Gray's Anatomy (1918) describes it as a soft, purplish organ about the size of a fist.

• What is the thymus?

  It is called the thymus. Gray's Anatomy (1918) describes it as a soft, lobed lymphoid organ.

• What is the thyroid gland?

  The thyroid gland is called the thyroid gland. Gray's Anatomy (1918) describes it as a butterfly-shaped endocrine gland with two lobes joined by a narrow isthmus.

• What are the adrenal glands?

  The adrenal glands is called the adrenal glands (suprarenal glands). Gray's Anatomy (1918) describes it as a pair of small, roughly triangular endocrine glands.

• What is the prostate?

  The the prostate is called the prostate gland. Gray's Anatomy (1918) describes it as a walnut-sized gland found only in the male.

• What is the uterus?

  The the uterus is called the uterus (womb). Gray's Anatomy (1918) describes it as a hollow, pear-shaped muscular organ.

• What is the largest organ in the body?

  The the skin is called the skin (integument). Gray's Anatomy (1918) describes it as the largest organ in the body.

• What are lymph nodes?

  The lymph nodes is called the lymph nodes. Gray's Anatomy (1918) describes it as small, bean-shaped organs of the immune system.

• What are the tonsils?

  The the tonsils is called the palatine tonsils. Gray's Anatomy (1918) describes it as a pair of oval masses of lymphoid tissue.