2235- midterm 1

functions of bones

support body, protects organs, calcium and phosphorus reservoir, movement, bone marrow- blood cells

periosteum

forms new bone and receives blood supply and nerves/ outer fibrous and inner cellular layer that covers the outer surface of bones.

endosteum

thin cellular layers that lines the medullary cavity, central cancal of osteons

the osteon (haversian system)

basic structural unit of compact bone. resists bending or fracture for the shaft of the long bones

osteogenic / osteoprogenitor cells (stem cells)

found at the cellular layer of the periosteum and endosteum. produce osteoblasts

osteoblasts (immature bone cells)

secrete osteoid to cause bone growth. turns into osteocytes

osteocytes

star shaped to connect to each other via cytoplasmic extensions. maintain protein and mineral content of matrix. help repair damaged bone

osteoclasts

giant, multinucleated cells. secretes acids and proteins, causes bone reabsorption and remodeling by breaking down bone tissue.

orientation of the scaphoid

20-degrees anterior from the dorsal surface

appositional growth

growth of bone thickness. compact bone is formed by the integration of new osteons

interstitial growth

process by which long bones increase in length through the addition of new cartilage between the existing cartilage at the growth plate.

importance of calcium homeostasis

enzymatic and neural function, muscle contraction, coagulation for maintaining bone density and preventing osteoporosis.

calcitonin

secreted in response to high plasma calcium. Builds bone, inhibits osteoblasts, stimulates osteoblasts, inhibits calcium reabsorption

parathyroid hormone (PTH) / parathormone

secreted in response to low calcium in plasma. stimulates osteoclasts, inhibits osteoblasts, stimulates calcium reabsorption, increases calcium absorptions

desmosomes

intercalated discs: hold cardiac myocytes together. ensures syncing of muscle contraction

gap junctions

intercalated discs: permit flow of local current between adjacent cardiac myocytes → facilitates propagation of the cardiac action potential from one cardiac myocytes to the next

skeletal myocyte

contraction dictated by somatic motor neuron innervations (Ach) release- requires neural input. depolarization of the sarcolemma stimulates the sarcoplasmic reticulum to release calcium that stimulates myocyte contraction

cardiac myocyte

dictated by incoming depolarizing local current provided by connected autorhythmic cells or contractile cardiac myocytes. no neural input is required, moves based off the need of contraction. depolarization causes an influx of calcium

hinge joints

moves in one axis. one bone end has a convex surface, fits into concave surface on partner bone end

bicondylar joints

more freely in one axis but have minimal movement in a second axis (biaxial). two rounded condyles of one bone articulate with a flat / concave surface of partner bone

elliposid joints

move freely in two axis

symphyses

joints interconnected separated bones with a fibrocartilage disc between them. bone ends are covered with hyaline cartilage. joint is well supported with surrounding ligaments- allowing for minimal movement (ex, PS, IV disc spaces)

14 phalanges, 5 metacarpals, 8 carpals

the categories of the 27 bones of the hand

ways to locate the ANS

small depression just distal to the radial styloid. can also be found using the distal crease on the anterior surface of the wrist

scaphoid position

this bone lies at a 20-degree angle from the dorsal surface

the distal radial margins are not in the same plane

why does the radiocarpal joint appear closed in the PA wrist projection (hint: the posterior end is more posterior)

radial tuberosity

bony prominence on the medial aspect of the radius directed towards the ulna. it is the insertion site for the tendon of the biceps muscle

ulnar styloid

projects distally from the medial aspect of the ulnar head. located at the level of the proximal and medial crease on the posterior wrist. sits more distal than its counterpart.

trochlear notch

articulates with the trochlea of the distal humerus. Forms a hinge joint for flexion and extension of the elbow. anterior surface of the olecranon and the superior surface of the coronoid participate its formation

distal radius crosses over the distal ulna

what happens to the radius and ulna when the forearm moves from an AP to a PA position

carrying angle

lateral aspect of the arm forms a 170 degree angle. lateral angulation is caused by the medial trochlea which is larger than the lateral. allows a swinging movement of the arms to clear the width of the pelvis. this is called the…

humerus condyles

refers to the entire articular surface of the distal humerus that articulates with the bones of the forearm to form the elbow joint. there are two parts - capitulum and trochlea

humerus anatomical neck

located just distal to the HH. separates the head of the humerus from the shaft medially and the tuberosities laterally. location of the epiphyseal growth plate. rare place for Fx to occur as the oblique line runs through the thickest part of the bone

greater tuberosity

located on the postero-lateral side of the humerus and is best in profile radiographically in true AP. a site for the attachment of the supraspinatus, infraspinatus and teres minor muscles. (these muscles wrap the shoulder and allow for full range of arm motion)

clavicle

first bone to ossify in utero. connects the arm and shoulder girdle to the axial skeleton. lacks a medullar cavity (contains no bone marrow). it is a cancellous bone covered by cortical bone. Has the conoid tubercle on teh inferior and lateral end. the medial 2/3 is convex (towards anterior), lateral 1/3 is concave (from anterior)

glenoid cavity

a fossa that is a pear shaped surface that sits on the upper lateral border of the scapula. it is directed superior, lateral, and anterior to meet the HH = glenohumeral joint. in AP, the surface lies at a 35-degree angle anteriorly