Sections
Key Terms
Key Terms
- abduction
- when a bone moves away from the midline of the body
- acetylcholinesterase
- (AChE) enzyme that breaks down ACh into acetyl and choline
- actin
- globular contractile protein that interacts with myosin for muscle contraction
- adduction
- movement of the limbs inward after abduction
- amphiarthrosis
- joint that allows slight movement; includes syndesmoses and symphyses
- angular movement
- produced when the angle between the bones of a joint changes
- appendicular skeleton
- composed of the bones of the upper limbs, which function to grasp and manipulate objects, and the lower limbs, which permit locomotion
- appositional growth
- increase in the diameter of bones by the addition of bone tissue at the surface of bones
- articulation
- any place where two bones are joined
- auditory ossicle
- also, middle ear, transduces sounds from the air into vibrations in the fluid-filled cochlea
- axial skeleton
- forms the central axis of the body and includes the bones of the skull, the ossicles of the middle ear, the hyoid bone of the throat, the vertebral column, and the thoracic cage, or ribcage
- ball-and-socket joint
- joint with a rounded, ball-like end of one bone fitting into a cuplike socket of another bone
- bone
- also, osseous tissue, connective tissue that constitutes the endoskeleton
- bone remodeling
- replacement of old bone tissue by new bone tissue
- calcification
- process of deposition of mineral salts in the collagen fiber matrix that crystallizes and hardens the tissue
- cardiac muscle
- tissue muscle tissue found only in the heart; cardiac contractions pump blood throughout the body and maintain blood pressure
- carpus
- eight bones that comprise the wrist
- cartilaginous joint
- joint in which the bones are connected by cartilage
- circumduction
- movement of a limb in a circular motion.
- clavicle
- S-shaped bone that positions the arms laterally
- compact bone
- forms the hard external layer of all bones
- condyloid joint
- oval-shaped end of one bone fitting into a similarly oval-shaped hollow of another bone
- coxal bone
- hip bone
- cranial bone
- one of eight bones that form the cranial cavity that encloses the brain and serves as an attachment site for the muscles of the head and neck
- depression
- movement downward of a bone, such as after the shoulders are shrugged and the scapulae return to their normal position from an elevated position; opposite of elevation
- diaphysis
- central shaft of bone, contains bone marrow in a marrow cavity
- diarthrosis
- joint that allows for free movement of the joint; found in synovial joints
- dorsiflexion
- bending at the ankle such that the toes are lifted toward the knee
- elevation
- movement of a bone upward, such as when the shoulders are shrugged, lifting the scapulae
- endochondral ossification
- process of bone development from hyaline cartilage
- endoskeleton
- skeleton of living cells that produce a hard, mineralized tissue located within the soft tissue of organisms
- epiphyseal plate
- region between the diaphysis and epiphysis that is responsible for the lengthwise growth of long bones
- epiphysis
- rounded end of bone, covered with articular cartilage and filled with red bone marrow, which produces blood cells
- eversion
- movement of the sole of the foot outward, away from the midline of the body; opposite of inversion
- exoskeleton
- secreted cellular product external skeleton that consists of a hard encasement on the surface of an organism
- extension
- movement in which the angle between the bones of a joint increases; opposite of flexion
- facial bone
- one of the 14 bones that form the face; provides cavities for the sense organseyes, mouth, and noseand attachment points for facial muscles
- femur
- also, thighbone, longest, heaviest, and strongest bone in the body
- fibrous joint
- joint held together by fibrous connective tissue
- fibula
- also, calf bone, parallels and articulates with the tibia
- flat bone
- thin and relatively broad bone found where extensive protection of organs is required or where broad surfaces of muscle attachment are required
- flexion
- movement in which the angle between the bones decreases; opposite of extension
- forearm
- extends from the elbow to the wrist and consists of two bones: the ulna and the radius
- gliding movement
- when relatively flat bone surfaces move past each other
- gomphosis
- joint in which the tooth fits into the socket like a peg
- Haversian canal
- contains the bone’s blood vessels and nerve fibers
- hinge joint
- slightly rounded end of one bone fits into the slightly hollow end of the other bone
- humerus
- only bone of the arm
- hydrostatic skeleton
- skeleton that consists of aqueous fluid held under pressure in a closed body compartment
- hyoid bone
- lies below the mandible in the front of the neck
- hyperextension
- extension past the regular anatomical position
- intervertebral disc
- composed of fibrous cartilage; lies between adjacent vertebrae from the second cervical vertebra to the sacrum
- intramembranous ossification
- process of bone development from fibrous membranes
- inversion
- soles of the feet moving inward, toward the midline of the body
- irregular bone
- bone with complex shapes; examples include vertebrae and hip bones
- joint
- point at which two or more bones meet
- lamella
- layer of compact tissue that surrounds a central canal called the Haversian canal
- lateral rotation
- rotation away from the midline of the body
- long bone
- bone that is longer than wide, and has a shaft and two ends
- lower limb
- consists of the thigh, the leg, and the foot
- medial rotation
- rotation toward the midline of the body
- metacarpus
- five bones that comprise the palm
- metatarsal
- one of the five bones of the foot
- motor end plate
- sarcolemma of the muscle fiber that interacts with the neuron
- myofibril
- long cylindrical structures that lie parallel to the muscle fiber
- myofilament
- small structures that make up myofibrils
- myosin
- contractile protein that interacts with actin for muscle contraction
- opposition
- movement of the thumb toward the fingers of the same hand, making it possible to grasp and hold objects
- osseous tissue
- connective tissue that constitutes the endoskeleton
- ossification
- also, osteogenesis, process of bone formation by osteoblasts
- osteoblast
- bone cell responsible for bone formation
- osteoclast
- large bone cells with up to 50 nuclei, responsible for bone remodeling
- osteocyte
- mature bone cells and the main cell in bone tissue
- osteon
- cylindrical structure aligned parallel to the long axis of the bone
- patella
- also, kneecap, triangular bone that lies anterior to the knee joint
- pectoral girdle
- bones that transmit the force generated by the upper limbs to the axial skeleton
- pelvic girdle
- bones that transmit the force generated by the lower limbs to the axial skeleton
- phalange
- one of the bones of the fingers or toes
- pivot joint
- joint with the rounded end of one bone fitting into a ring formed by the other bone
- planar joint
- joint with bones whose articulating surfaces are flat
- plantar flexion
- bending at the ankle such that the heel is lifted, such as when standing on the toes
- pronation
- movement in which the palm faces backward
- protraction
- anterior movement of a bone in the horizontal plane
- radius
- bone located along the lateral, or thumb, side of the forearm; articulates with the humerus at the elbow
- resorption
- process by which osteoclasts release minerals stored in bones
- retraction
- movement in which a joint moves back into position after protraction
- rib
- one of 12 pairs of long, curved bones that attach to the thoracic vertebrae and curve toward the front of the body to form the ribcage
- rotational movement
- movement of a bone as it rotates around its own longitudinal axis
- saddle joint
- joint with concave and convex portions that fit together; named because the ends of each bone resemble a saddle
- sarcolemma
- plasma membrane of a skeletal muscle fiber
- sarcomere
- functional unit of skeletal muscle
- scapula
- flat, triangular bone located at the posterior pectoral girdle
- sesamoid bone
- small, flat bone shaped like a sesame seed; develops inside tendons
- short bone
- bone that has the same width and length, giving it a cube-like shape
- skeletal muscle tissue
- forms skeletal muscles, which attach to bones and control locomotion and any movement that can be consciously controlled
- skull
- bone that supports the structures of the face and protects the brain
- smooth muscle
- tissue occurs in the walls of hollow organs such as the intestines, stomach, and urinary bladder, and around passages such as the respiratory tract and blood vessels
- spongy bone tissue
- forms the inner layer of all bones
- sternum
- also, breastbone, long, flat bone located at the front of the chest
- supination
- movement of the radius and ulna bones of the forearm so that the palm faces forward
- suture
- short fiber of connective tissue that holds the skull bones tightly in place; found only in the skull
- suture bone
- small, flat, irregularly shaped bone that forms between the flat bones of the cranium
- symphysis
- hyaline cartilage covers the end of the bone, but the connection between bones occurs through fibrocartilage; symphyses are found at the joints between vertebrae
- synarthrosis
- joint that is immovable
- synchondrosis
- bones joined by hyaline cartilage; synchondroses are found in the epiphyseal plates of growing bones in children
- syndesmosis
- joint in which the bones are connected by a band of connective tissue, allowing for more movement than in a suture
- synovial joint
- only joint that has a space between the adjoining bones
- tarsal
- one of the seven bones of the ankle
- thick filament
- group of myosin molecules
- thin filament
- two polymers of actin wound together along with tropomyosin and troponin
- thoracic cage
- also, ribcage, skeleton of the chest, which consists of the ribs, thoracic vertebrae, sternum, and costal cartilages
- tibia
- also, shinbone, large bone of the leg that is located directly below the knee
- trabeculae
- lamellae that are arranged as rods or plates
- tropomyosin
- acts to block myosin binding sites on actin molecules, preventing cross-bridge formation and preventing contraction until a muscle receives a neuron signal
- troponin
- binds to tropomyosin and helps to position it on the actin molecule, and also binds calcium ions
- ulna
- bone located on the medial aspect, pinky-finger side, of the forearm
- vertebral column
- also, spine, surrounds and protects the spinal cord, supports the head, and acts as an attachment point for ribs and muscles of the back and neck