Anatomical Terms and Positions

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Anatomical Position

• The arms are near the sides with palms facing forward; there is a need for an anatomical position.

Proximal and Distal

• These terms relate to the head within the limbs.
• Used to describe which tibiofibular joint is closer to the head.
• Proximal means closer to the head.
• Distal means further away from the head.

Lateral and Medial

• These terms relate to the midline.
• Medial refers to closer to the midline.
• Lateral means further away from the midline.

Superior and Inferior

• Apply to the head, neck, and trunk.
• Supra (above) means higher.
• Infra or sub (below) means lower.

Deep and Superficial

• Deep structures are closer to the interior of the body.
• Superficial structures are closer to the exterior surface of the body.
• Deep is closer to the internal body, while superficial is closer to the surface.

Anterior and Posterior

• Anterior is the front; posterior is the back.
• Indicates in front of or behind.

Transverse/Horizontal Plane

• Divides the body into superior (upper) and inferior (lower) sections.

Frontal/Coronal Plane

• Divides the body into anterior (front) and posterior (back) sections.

Sagittal Plane

• Divides the body into left and right sections.

Bones

• Living, growing tissue made of collagen (protein) and calcium (mineral).
• Provide support, store minerals and lipids, offer protection, produce blood cells, and provide leverage.

Bone Marrow

• Made up of fats and cells.

Structure

• Periosteum: outer membrane.
• Cortical bone: dense outer layer.
• Trabecular (spongy) bone: struts and plates.
• Medullary cavity.

Lumps and Bumps

• Include spine, crest, line, foramen, ramus, and fossa.
• Not all bones are smooth, increasing the surface area for attachment.

Articular Surfaces

• These include facet, tubercle, and condyle.
• Bones communicate with each other using articular surfaces of different shapes.
• Cartilage exists between bones where they meet.
• These surfaces can be rounded or flat.

Depressions

• Fossa represents a pit-like depression.
• Sulcus is a smaller groove or fissure.
• Muscles and organs can be located in these areas.
• Intertubercular areas exist, and long bones have a head, neck, and sulcus.

Openings

• Foramen: opening.
• Canals: passage.

Structures

• Air filled with chambers.

Classification of Joints

• Based on motion available:
  • Synarthrosis: no motion.
  • Amphiarthrosis: a little motion.
  • Diarthrosis: most motion.
• Based on structure:
  • Bony.
  • Fibrous.
  • Cartilaginous.
  • Synovial.
• Some joints are met with fibers or cartilage.
• Most joints studied are synovial joints that move.

Synovial Joints

• Joint capsule encloses the two ends of the bone.
• Synovial membrane has a good blood supply, producing synovial fluid to lubricate the bone ends.
• Articular surface is covered in cartilage.
• Hyaline cartilage is white, strong, and fit to support weight.
• Synovial fluid pushes into joint cavities, acting as a lubricant.

Muscles

• Cardiac muscle is regulated by the heart's pacemaker and is involuntary.
• Smooth muscle is in arteries, digestive, and urinary tracts, and is involuntary.
• Skeletal muscles produce skeletal movement.

Muscle Features

• Origin: muscle fibers on a bone cross a joint and form a tendon.
• Insertion: where it attaches to skeletal muscles to bones.
• Action: contraction of muscle pulls insertion towards origin.
• Innervation: the nerve gives the muscle its message via a motor neuron.

Muscle Contractions

• Muscles performing intended motions are prime movers/agonists.
• Muscles performing opposite motions are antagonists and relax while the prime mover contracts.
• Concentric contraction: muscle gets shorter as it moves the body part.
• Eccentric contraction: muscle allows itself to get longer.
• Isometric contraction: muscle stays the same length.

Nervous System

• CNS: brain and spinal cord.
• PNS: nerves outside the CNS.
• Afferent neurons (sensory): neurons send impulses to the CNS.
• Efferent neurons: motor signals from the CNS to the peripheral system.
• SAME (sensory = afferent, motor = efferent).

Peripheral Nervous System (PNS)

• Has both somatic and autonomic components.
• Somatic: muscles are being told what to do, and is voluntary.
• Autonomic: sensory nerve connects to receptors without conscious knowledge.
• Motor nerve helps the body return to normal.
• Both sensory and motor neurons are used in both systems.
• Spinal nerve: a mixed motor and sensory nerve.
• Carries signals between the spinal cord and body.
• Most mingle and share axons to form a nerve plexus.
• Goes to the muscles and organelles.

Spinal Nerves

• Named by letter + number:
  • Letter indicates the region of the spine: cervical (neck), thoracic (chest), lumbar (low back), sacral (behind pelvis). Number: the number of the vertebrae adjacent to where the nerve leaves the spinal cord.
• Transverse plane, superior and inferior.
• Vertical canal is protected by bone.
• The spinal cord is located in the canal and protected.
• Motor nerve leaving spinal nerve joins spinal nerve, creating a peripheral nerve.
• Sensory fibers travel into the spinal curve.
• Nerves receive sympathetic nerve innervation as they leave.

Function of the Pelvis

• Withstands weight bearing and locomotion.
• Provides strength and stability over mobility.
• Protects organs of reproduction, digestion, and urination.
• Links the trunk to the lower limbs.

Structure

• Os coxae.
• Fused after puberty.
• The ilium is on the superior lateral side.
• The sacrum is on the superior medial side.
• The pubis is on the inferior medial side.
• The ischium is on the inferior lateral side.

Pelvic Structure

• Sacrum: 5 sacral vertebra.
• The ilium, ischium, and pubis fuse after puberty.
• Underneath the sacrum is the coccyx, consisting of coccygeal vertebrae.

Landmarks

• The ilium is superior, featuring a large iliac crest and an iliac fossa (a slightly large flat surface).
• The ilium has two spines: the anterior superior iliac spine (top) and the anterior inferior iliac spine (low).
• The acetabulum, where the head of the femur fits, is a fossa located at the hip joint.
• Formed by a combination of the ilium (posterior), pubis (anterior), and ischium (posterior).
• The obturator foramen is the large opening between the pubis and ischium.
• The sacrum is the triangular bone below the lumbar vertebrae.
• The coccyx is located below the sacrum.

Joints

• The sacroiliac joint is a synovial joint, located between the sacrum and ilium.
• It is not a very mobile joint but has strong ligaments posteriorly and anteriorly to reinforce it.

Pubic Symphysis

• Allows little movement.
• Made of fibrocartilaginous disc.
• Reinforced by the superior and inferior pubic ligaments.
• Helps hold the front of the pelvis together.

Male and Female Pelvis

• Male: the ilium bone is taller and narrower; and has a subpubic angle of 90 degrees or less.
• Female: wider, with a subpubic angle of 100 degrees or more.

Arteries and Veins of the Pelvis

• Arteries and veins often travel together.

Blood Supply to the Urinary System

• Vena cava (blue) returns deoxygenated blood to the heart.
• Each vena cava has a renal vein to the kidney.
• Blood returns from the kidney to the heart via renal veins.
• Arteries (red) come from the abdominal part of the aorta.
• Aorta arteries have two renal arteries into the kidneys.
• The ureter transports urine from the kidneys to the bladder.
• The bladder gets its blood supply from the aorta, which divides into two in the pelvis (common iliac). This divides again into internal iliac veins and arteries supplying the bladder.

Kidneys

• Bean-shaped, approximately 12 cm.
• Retroperitoneal (behind the peritoneum), located behind the abdominal cavity.
• Located between T12 and L3.
• Renal pelvis: area at the center of the kidney; urine collects here and is channeled to the ureter.
• Ureter starts at the renal hilum, which is the entry and exit point for the renal artery, renal vein, ureter, and nerves.
• The renal vein and renal artery can filter 1.4 cardiac output every minute.

Kidney Functions

• Regulate blood pressure via salt water.
• Excrete wastes (e.g., urea).
• Reabsorb water.
• Adrenal glands produce hormones to regulate water.

Ureters

• Hollow muscular tube.
• Transports urine from the renal pelvis to the urinary bladder.
• Backflow is discouraged as the bladder fills.

Urinary Bladder and Innervation

• The small muscle walls consist of the detrusor.
• Sympathetic T12 to L2: relaxation of the detrusor (urine retention).
• Parasympathetic S2-S4: contraction of the detrusor muscle (micturition).
• Hollow and muscular, made of smooth muscle.
• Somatic external urethral sphincter.
• The detrusor muscle contracts to urinate.
• The lower spinal cord controls it.

Urethra

• Passage of urine and semen in males; involved in urinary and reproductive functions.
• The female urethra is 4 cm long, anterior to the vagina, and solely urinary.
• The male urethra is 20 cm long.

Female Reproductive System

• Ovaries (2) connect to the uterus, cervix, and vagina.
• External genitalia.
• Mammary glands.

Uterus

• Thick-walled muscular organ between the urinary bladder and the rectum.
• Ligaments hold it in place.
• Hollow cavity.

Ovaries and Fallopian Tubes

• First-degree reproductive organs, in size of an organ.
• Form ova (gonads) and hormones (glands).
• Supported by ligaments and inner lining tissues.
• Fallopian tubes are narrow tunnels where ova (egg cells) pass from the ovaries to the uterus.
• Conception normally occurs here.
• Communicated laterally and is endocrine.

Vagina

• Fibromuscular tube from the uterus to the outside.
• Allows sperm but protects against other items entering.
• Not the passage for urine and is supported by pelvic floor muscles.

External Genitalia (Perineum - Female)

• Mons pubis is fatty tissue covering the pubic bone; glands there release pheromones.
• Labia majora enclose and protect, with sweat and sebaceous glands, which produce lubricating secretions.
• Labia minora are inside the labia major and surround openings of the vagina and urethra.
• The clitoris is a protrusion of erectile tissue.
• Bartholin glands secrete lubricant near the opening of the vagina.

Male Reproductive System

• Testes produce hormones and sperm.
• Ductus is for transport, storage, and maturation of sperm.
• Nerves, arteries, and veins run through the pelvis.
• Seminal vesicle contributes fluid to sperm, making semen.
• Glands: prostate, seminal vesicle.
• Ductus moves sperm away from its storage site in the testicle, transporting mature sperm to the urethra for ejaculation.
• The ductus carries sperm to drain into the prostate.
• Fluid drains through the urethra and can be ejaculated.
• Sperm collects from the testicles and fluid from the seminal vesicle and prostate make semen for ejaculation.
• The prostate can enlarge and interrupt urinary flow.
• The shared urethra functions for both urinary and reproductive systems.

Scrotum

• It supports testes.
• The dartos and cremaster muscles are in the scrotal wall.
• It is smooth muscle.
• Testes are able to move for temperature control.

Testes (Primary Reproductive Organ)

• The epididymis continues as the vas deferens.
• Sperm is produced here.
• The epididymus stores sperm, allows them to mature, and then they can pass through the ductus.

Passage of Semen

• 2 testicles.
• 2 epididymus
• 2 vas deferens
• (via 2 seminal vesicles)
• Into one prostate
• Into one urethra.

Penis

• The glans (head of the penis) is covered with pink, moist mucosa.
• Foreskin is mobile skin over the glans.
• Corpus cavernosa: two columns of tissue on the sides that fill with blood during erection.
• Corpus spongiosum: column of spongy tissue along the front of the penis to the glans, keeps the urethra open.
• The urethra runs through the corpus spongiosum, carrying ejaculatory fluid.

Perineum

• Interior to the pelvic floor.
• Between the thighs.
• Diamond shaped.
• Women have three outlets, men have two.
• Skin, fascia, external genitalia, glands, and muscle.

Pelvic Floor

• Resists increases in intra-abdominal pressure.
• Creates external sphincters.
• Supports organs.
• Anterior ramus of S4 and branches of the pudendal nerve.
• Bowl-shaped bone which is under voluntary control.
• Innervation is by the anterior ramus and branches of the pudendal nerve
• Reproductive and urinary organs above, perineal muscles, and external genitalia below.
• Consists of Coccygeus and Levator Ani.
• Voluntary Sphincters.
• From Pubic bone to coccyx.
• Holes pass through it.

Hip Joint

• It is a synovial joint.
• it is a type of joint that is a ball-and-socket joint.
• Consists of the acetabulum and the femur.

Acetabulum

• Consists of a deep fossa.
• Has a horseshoe-shaped fibrocartilaginous lining (fibrocartilage pad).
• Consists of a fat pad in the center of the fossa with a fibrocartilaginous pad on top, along with the transverse acetabular ligament spanning the acetabular notch at the bottom.
• Includes a ligament attached to the femoral head and acetabulum.
• Acetabular labrum is a lip that deepens the socket.

Proximal Femur

• Consists of a head and neck and is the proximal part of the femur.
• The head sits within the acetabulum.
• Has articular cartilage on the ends, as it is a synovial joint.
• Features a greater trochanter protruding at the top and a lesser trochanter inside on the medial.
• The intertrochanteric line runs on the anterior between the greater and lesser trochanters.

Ligaments

• The capsule is dense and strong.
• Encloses the head and neck of the femur.
• Become taut when the leg is extended.
• Run from the rim of the acetabulum to the intertrochanteric line on the anterior to the intertrochanteric crest on the posterior.
• Woven into the fibers on the joint capsule, there are 3 ligaments.
  • The iliofemoral ligament runs from the ilium to the femur on the anterior.
  • The pubofemoral ligament runs from the pubic bone to the femur on the anterior.
  • The ischiofemoral ligament runs from the ischium to the femur on the posterior.

Angle of Inclination

• Occurs between the neck and shaft of the femur.
• In adults, the angle is about 115 to 140 degrees.
• Females have a smaller angle due to their wider pelvis compared to males; the femurs are set further apart.
• With a wider angle, the knees are further apart; if the angle is smaller, the knees are closer together.

Stability

• Provides good stability due to lots of articular surface that make contact.
• The head of the femur is enclosed in the socket where the cartilage, fat, and ligaments are.
• Thick intracapsular ligaments also contribute to hip stability: iliofemoral, pubofemoral, and ischiofemoral.

Blood Supply

• The aorta runs through the abdominal cavity, dividing into the two common iliac arteries in the pelvis.
• The common iliac artery then divides again into the internal and external iliac arteries.
• The external iliac artery travels from the front of the pelvis to the thigh, under the muscles of the abdomen.
• It passes through the transitional zone where the inguinal ligament is, and where there are nerves, tendons, arteries, and veins.
• This external iliac artery then turns into the femoral artery.
• The same happens with the inferior vena cava, but the external iliac vein turns into the femoral vein.

Motions

• The sagittal plane has two movements: flexion (forward) and extension (exit) of the hip.
• Front has two movements: abduction (away from midline) and adduction (toward midline).
• The transverse plane has two movements: internal rotation and external rotation.

Hip Motions

• Muscles can be grouped by their actions and compartments.
• Grouping muscles by compartments helps in remembering innervation.

Extensors

• Gluteus maximus.
  • Originates at the ilium, sacrum, coccyx, and lumbar fascia.
  • Ends at the iliotibial tract and the gluteal tuberosity.
  • Action: extends the hip.
• Innervation: inferior gluteal (from L5 to S2).

Hip Innervation

• The innervation is the nerves that supply that structure.
• The superior and inferior gluteal nerves innervate the gluteals.
• The nerves travel with their corresponding arteries and veins through the greater sciatic foramen; the superior nerve passes above the piriformis, while the inferior nerve passes below the piriformis.

Abductors and Rotators

• Gluteus medius and minimus.
  • Originates at the iliac crest between the posterior and anterior gluteal lines.
  • Inserts at the greater trochanter on the femur.
  • Action: abduct the hip and internally rotate the leg.
  • Innervation: from the superior gluteal nerve.
• The gluteus medius and minimus support the pelvis when standing on one leg.

Flexors and Abductors

• Tensor Fascia Latae (TFL).
  • Originates at the iliac crest and the anterior superior iliac spine.
  • Inserts at the iliotibial tract, which inserts into the lateral tibial condyle.
  • Action: flexion of the hip and abduction.
  • Innervation: from the superior gluteal nerve.

Rotators

• Lateral rotator group PGOGOQ.
• Learn where to find them and their action.
• Consists of:
  • Piriformis
  • Gemelli (superior and inferior)
  • Obturators (externus and internus)
  • Quadratus femoris
• This small group of muscles is deep to the gluteals.
• It inserts onto the posterior of the femur and can pull it back, which allows for external rotations.

Flexors

• Iliacus.
  • Originates on the iliac fossa.
  • Inserts on the lesser trochanter.
  • Action: flexion of the hip.
  • N: innervation occurs from the femoral.
• Located on the anterior side of the body to contract and flex the hip.
• Psoas Major.
  • Originates on T12 to L5 vertebrae, lumbar region of the spine.
  • Inserts on the lesser trochanter.
  • Action: flex the hip.
  • Innervation: from the lumbar plexus, L2 to L3.

Muscles of the Hip and Knee

• Contains muscles that cross over the hip and knee joint.
• Contain muscles that act on the hip and muscles that act on the knee.
• Quadriceps refers to the anterior compartment.
• Hamstrings refers to the posterior compartment.
• Adductors refers to the medial compartment.

Hip Flexors and Knee Extensors (Nerves of the Thigh)

• Femoral nerve:
  • Made of spinal nerve roots from L2 to L4.
  • Passes through the femoral triangle.
  • Enters the anterior compartment of the thigh.
  • Runs with the femoral artery and vein on the anterior of the femur.
• Hip Flexor and Knee Extensor:
  • Quadriceps, Rectus Femoris (Superficial):
    • Originates at the anterior inferior iliac spine and the upper acetabulum.
    • Inserts onto the tibial tuberosity.
    • Action: flexion of the hip and extension of the knee.
    • Innervation: from the femoral nerve.
• Knee Extensor:
  • Quadriceps (Vasti):
    • Vastus intermedius, Vastus lateralis, Vastus medialis.
    • Inserts itself at the tibial tuberosity.
    • Action: extension of the knee.
    • Innervation: at the femoral nerve.

Hip Flexors

• Sartorius:
  • Originates from the anterior superior iliac spine.
  • Inserts at the medial tibia near the tibial tuberosity.
  • Action: knee flexion, hip flexion, abduction, and lateral rotation.
  • Innervation: femoral nerve.

Hip Adductors

• Obturator nerve:
  • Made of spinal nerves from L2 to L4.
  • Passes through the obturator foramen.
  • Enters the medial compartment of the thigh.
• Learn As a Group: 5 muscles: gracilis, obturator externus, adductor brevis, adductor longus, and adductor magnus.
  • Has different origins and different insertion points.
  • Action: adduction of the hip.
  • Innervation: by the obturator nerve.
• The abductor nerve adducts the hip
• Supports the pelvis when standing.
• The adductor magnus can extend the hip, and the pectineus can flex the hip.
• All compartments of the medial thigh adduct the hip.

Hip Extensors and Knee Flexors

• Posterior thigh: knee flexors.
• Known as the hamstrings.
• Consists of the biceps femoris, semimembranosus, and semitendinosus.
• Sciatic nerve - branches.

Hip Extensors and Knee Flexors

Sciatic Nerve

• Spinal nerves L4 to L5 and S1 to S3 make it up.
• It passes through the sciatic foramen and the sciatic notch; ligaments close it up, making it a foramen.
• Enters the posterior compartments of the thigh.
• The superior and inferior gluteal nerves also run through it, with their respective veins and arteries.
• Hip Extensor and Knee Flexor
• Bicep Femoris:
  • Originates near the Ischial.
  • Inserts head of the fibula.
  • Action includes extension of the hip and flexion of the knee.
  • Innervated by the tibial nerve.
• Semimembranosus and Semitendinosus:
  • Originates near the Ischial tuberosity.
  • Inserts on the medial condyle and the tibia.
  • Action is Hip extension and Knee flexion.
  • Innervated by the sciatic nerve.