Anatomy and Bone Strux: Key Terms and Concepts

Lecture 1

What is anatomical position?

Standing upright, facing forward, arms at sides, palms forward.

Why is anatomical position important?

It serves as the reference point for all anatomical terminology.

What does the sagittal plane divide?

Divides the body into left and right portions.

What does the median sagittal plane divide?

Divides the body into equal left and right halves.

What does the transverse (horizontal) plane divide?

Divides the body into top (superior) and bottom portions.

What does the coronal (frontal) plane divide?

Divides the body into front and back portions.

What does mesial mean (dental)?

Toward the midline of the dental arch.

What does distal mean (dental)?

Away from the midline of the dental arch.

What does labial mean?

Toward the lips.

What does lingual mean?

Toward the tongue.

What does buccal mean?

Toward the cheek.

What does palmar mean?

Toward the palm of the hand.

What does dorsal (hand/foot) mean?

Toward the back of the hand or top of the foot.

What does ipsilateral mean?

On the same side of the body.

What does contralateral mean?

On the opposite side of the body.

What is circumduction?

Circular movement combining flexion, extension, abduction, and adduction.

What is supination?

Palm faces anteriorly or upward.

What is pronation?

Palm faces posteriorly or downward.

What is inversion?

Sole of foot turns medially.

What is eversion?

Sole of foot turns laterally.

What is opposition (thumb)?

Combination of flexion, abduction, and medial rotation.

What are the five key functions of bone?

Growth response, fracture healing, blood cell production, calcium homeostasis, and physical stress adaptation.

What is hematopoiesis?

The process of producing red and white blood cells in bone marrow.

What is modeling and remodeling in bone?

Bone's response to physical stress by reshaping and renewing its structure.

Where is compact (cortical) bone found?

On the outer surfaces of long, flat, and irregular bones.

Where is trabecular (spongy) bone found?

Inside long, flat, and irregular bones.

What is the epiphysis?

The rounded end of a long bone, located at both proximal and distal ends.

What is the metaphysis?

The region between the epiphysis and diaphysis; contains the growth plate in developing bones.

What is the diaphysis?

The shaft or central part of a long bone.

What is the medullary cavity?

The hollow interior of the diaphysis that contains bone marrow.

What is the periosteum?

A two-layered membrane covering the outer surface of bone; includes a fibrous outer layer and a cellular inner layer.

What is the endosteum?

A thin membrane lining the inner surfaces of bone, similar in structure to the periosteum.

What is articular cartilage?

Hyaline cartilage covering the ends of long bones where they form joints.

What is the epiphyseal line?

A remnant of the growth plate found in adult bones, marking the former site of bone growth.

What is the nutrient foramen?

A small opening in the bone through which blood vessels enter to nourish bone tissue.

What does an osteoblast do?

Deposits bone matrix.

What does an osteoclast do?

Resorbs bone matrix.

What does an osteocyte do?

Maintains bone matrix.

Where are osteoblasts and osteoclasts located?

On bone surfaces.

Where are osteocytes located?

Within the bony matrix.

What stem cells give rise to osteoblasts?

Mesenchymal stem cells.

What stem cells give rise to osteoclasts?

Hematopoietic stem cells.

What is an osteon?

A structural unit of compact bone containing a central Haversian canal.

What does the Haversian canal contain?

Nerves and blood vessels.

How is trabecular bone organized?

Lamellar structure with osteocytes and canaliculi, but few or no Haversian or Volkmann's canals.

What are short bones?

Cube-shaped bones like carpals and tarsals.

What are sesamoid bones?

Bones found within tendons, such as the patella.

What is primary osteoporosis?

Age-related bone loss: Type I (post-menopausal women), Type II (elderly).

What is secondary osteoporosis?

Bone loss due to lifestyle, medication, or disease.

Why is trabecular bone more affected by osteoporosis?

It has a larger surface area and is more metabolically active.

What is the axial skeleton?

Includes the skull, vertebrae, ribs, and sternum.

What is the appendicular skeleton?

Includes the upper and lower limbs, pelvis, scapulae, and clavicles.

What are the three main types of joints?

Fibrous, cartilaginous, and synovial.

What is a suture joint?

Fibrous joint with very low mobility, found between skull bones. Synarthrosis

What is a gomphosis joint?

Fibrous joint holding teeth in their sockets. Synarthrosis

What is a syndesmosis joint?

Fibrous joint connecting long bones like radius/ulna or tibia/fibula. Synarthrosis

What is a symphysis joint?

Cartilaginous joint made of fibrocartilage, found in pubic bones and intervertebral discs. Functions to allow slight movement between bones.

What is a synchondrosis joint?

Cartilaginous joint made of hyaline cartilage, found in epiphyseal plates and 1st sternocostal joint. Limited movement.

What is a synovial joint?

Highly mobile joint with a fluid-filled cavity, joint capsule, synovial membrane, and articular cartilage. Lots of movement (diarthrosis)

What are the mobility classifications of joints?

Diarthrosis (high), Amphiarthrosis (slight), Synarthrosis (very low/none).

What are the three types of muscle tissue?

Skeletal, cardiac, and smooth.

What are the features of skeletal muscle?

Long, tubular, striated cells; voluntary movement.

What are the features of cardiac muscle?

Y-shaped, striated cells found only in the heart; involuntary.

What are the features of smooth muscle?

Spindle-shaped cells in walls of internal organs; involuntary.

What is a muscle compartment?

A group of muscles with similar function, blood supply, and innervation, separated by fascia.

What is fascia?

Connective tissue that surrounds muscles, nerves, and vessels; composed of fibroblasts, collagen, elastin, and ground substance.

What is the origin of a muscle?

The attachment site on the stationary bone.

What is the insertion of a muscle?

The attachment site on the mobile bone.

What happens during muscle contraction?

The insertion is pulled toward the origin.

What is an agonist muscle?

The prime mover of a joint or structure.

What is a synergist muscle?

A muscle that works with the agonist to produce movement.

What is a fixator muscle?

A muscle that stabilizes the joint so agonists and synergists can act.

What is an antagonist muscle?

A muscle that performs the opposite action of the agonist to control movement speed.

What is the direction of blood flow in arteries?

Away from the heart.

What is the direction of blood flow in veins?

Toward the heart.

Do arteries or veins usually carry oxygenated blood?

Arteries usually carry oxygenated blood; veins usually carry deoxygenated blood (exceptions: pulmonary vessels).

What are the three layers of blood vessels?

Tunica intima, tunica media, tunica externa.

What is the tunica media composed of?

Smooth muscle; affects blood pressure.

What structural feature is unique to veins?

Valves that prevent backflow.

What is the skeletal muscle pump?

A mechanism that helps return venous blood to the heart using muscle contractions and valves.

What are elastic arteries?

Arteries with many elastic fibers; help accommodate pressure changes.

What are muscular arteries?

Arteries with more smooth muscle fibers; regulate blood flow.

What are arterioles?

Small arteries with few smooth muscle layers.

What are venules?

Small veins with thin walls and no valves.

What are capillaries?

Tiny vessels connecting arterioles and venules; composed only of tunica intima.

How does vessel diameter change in circulation?

Arteries decrease in diameter as they branch; veins increase in diameter as they converge.

Fibrous joint

A type of joint where bones are connected by fibrous tissue, restricting movement. Eg: sutures, syndesmos, and gomphoses.

Cartilaginous joint

A type of joint where bones are connected by cartilage, allowing more movement than fibrous joints but less than synovial joints. Eg Synchondrosis and symphysis joints.

Describe osteon organization in compact (cortical) and spongy (medullary/cancellous) bone.

Compact (cortical) bone is organized into dense concentric layers osteons, with a central Haversian canal. Spongy (trabecular) bone is organized into sheets of osteons that lack a Haversian but contain osteocytes in lacunae and are organized along lines of mechanical stress to maximize strength with minimal density

Flat bones vs long bones

Flat bones are broad, thin, often curved bones that protect internal organs and provide large surfaces for muscle attachment, such as the skull, ribs, and scapulae. Long bones are cylinder-shaped, being longer than they are wide, with a long central shaft and two bulky ends (epiphyses) that function as levers for movement

Types of synovial joints

CHiPS-B (condyloid, hinge, plane, pivot, Saddle, Ball and Socket

Plane

Sliding or gliding between flat surfaces. Intercarpal joints (b/t wrist bones)

Hinge

Flexion and extension in one plane (like a door hinge). Elbow

Pivot

Rotation around a single axis. Atlantoaxial joint (between C1 and C2 vertebrae in the neck)

Condyloid

Flexion, extension, abduction, adduction, and circumduction (in two planes: biaxial). Wrist joint (radiocarpal)

Saddle

biaxial (ab/ad, flex/extend/circumduction) but more movement. Base of thumb.

Ball and Socket Joint

multiaxial: flex/extend/rotat/ab/ad: shoulder

Tunica Media vs Tunica Externa: arteries vs veins

tunica media > arteries, tunica externa > veins