Anatomy Lecture Exam 2

Function of skeletal system

support, protection, movement, hemopoiesis, energy & mineral resevres

Skeleton

206 bones

axial skeleton

skull, hyoid bone, vertebral column, thoracic cage

axial skeleton functions

supports: head, neck, trunk

protects: brain, spinal cord, thoracic organs

appendicular skeleton

pectoral girdle, upper limbs, pelvic girdle, lower limbs

foramen (foramina)

hole in bone (for nerves and blood vessels)

Fossa (fossae)

depression in bone

Process

projection from bone, narrow or wide, protrudes from surrounding bone

Meatus

a hole or tube-like structure

canal

a groove or tube-like structure

cartilage tissue

support soft tissues, model for formation of bone, gliding surface at articulations

Hyaline cartilage

Most common type of cartilage

found: end of long bones, costal cartilages, respiratory structures, fetal skeleton

elastic cartilage

cartilage with abundant elastic fibers

very resilient and flexible

found: pinna (outer ear) and epiglottis

FIbrocartilage

thick, dense collagen fibers, resists strong compression

found: intervertebral discs, knee joint, pubic symphysis

Osteoblasts

build new bone

Osteoclasts

break down bone

osteocytes

mature bone cells

spongy bone

inside bones, better at shock absorption

compact bone

smooth, dense, external portion of bones strong, rigid

Lamellae

Concentric rings made up of groups of hollow tubes of bone matrix

osteon

structural unit of compact bone

haversian canal

one of a network of tubes running through compact bone that contains blood vessels and nerves

structure of long bone

Epiphysis (Ends)

Epiphyseal line (growth plate)

Diaphysis (shaft)

Compact bone (superficial)

Spongy bone (deep)

Periosteum (sheath on outside of bone)

Endosteum (lines internal cavity)

Medullary cavity (bone marrow)

Nutrient arteries (feed bone)

Articular cartilage on ends

Flat, irregular, and short bones

-compact bone with periosteum on outside

-spongy bone with endosteum inside

-contain marrow but don't have a marrow cavity

Bone development and growth

bones form by replacing connective tissues in the fetus; some form within sheet-like layers of connective tissue (intramembranous bones) while others replace masses of cartilage (endochondral bones)

intramembranous ossification

bone develops from a fibrous membrane

forms many flat bones (skull), maxillae, zygomatic, mandible, and center of clavicle

endochondral bone ossification

-Most of the bones of the skeleton form this way

1) Skeleton begins as Hyaline Cartilage model

2) Bone replaces cartilage

3) Epiphyseal (growth) plates ossify eventually

Closure of epiphyseal plate

-cartilage is gradually replaced by bone tissue on both sides of the epiphyseal plate (primary center of ossification at diaphysis, and secondary centers of ossification in epiphyses)

-when centers of ossification meet (at epiphyseal plate), growth stops

pectoral girdle: clavicles and scapulae

includes L & R scapulae and clavicles

scapulae do NOT join to the axial skeleton, articulation with the clavicle is very loose

attached to axial skeleton by way of associated muscles and ligaments

high flexibility, not very stable

Clavicle

collarbone, s-shaped

sternal end attaches to the sternum, acromial end attaches to scapula

function: provides muscle attachment, acts as brace for the scapula and arms

Scapula

posterior surface of rib cage (shoulder blade)

glenoid cavity (glenoid fossa) articulates with the humerus (= forms shoulder joint)

supraspinous and infraspinous fossae of scapula

attachment sites for muscles

Coracoid process of scapula

attachement point of the biceps muscle. located anteriorly

Acromion of scapula

articulates with acromial end of clavicle. located posteriorly

Humerus

The longest bone of the upper arm

head of humerus

articulates with scapula at the glenoid cavity

distal end of humerus

articulates with ulna and radius (elbow)

greater and lesser tubercles of humerus

sites for muscle attachment

deltoid tuberosity is attachment for deltoid muscle

fractures of humerus

Commonly occur in two places:

Surgical neck

Midshaft spiral fractures

nerves pass along both common places, can be damaged due to fractures. MAY lead to permanent upper limb dysfunction

trochlea of humerus

articulates with trochlear notch of ulna. trochlear notch fits over trochlea to create a hinge

Olecranon process of ulna

fits into the olecranon fossa of the humerus when forearm extends

lateral and medial epicondyles on humerus

attachment sites for forearm muscles

capitulum of humerus

articulates with head of radius

Ulna and Radius

lower arm bones, connected by interosseous membrane, allows bone to stay at a fixed distance and allows rotation

proximally, radial head articulates with radial notch on ulna

distally, each has as styloid process

forearm: pronation

radius crossed over ulna

forearm: supination

radius parallel to ulna

radial and ulnar styloid process

connects to the wrist by articulating with a ligament.

wrist fractures

Typically fracture distal radius while catching yourself during a fall

"Dinner-fork " presentation

Can lead to nerve damage and dysfunction

carpals

8 bones, 2 rows, make up wrist

Mnemonic: Straight Line To Pink, Here Comes The Thumb

L > R bottom row: Scaphoid, Lunate, Triquetrum

R < L top row: Hamate, Capitate, Trapezoid, Trapezium

metacarpals and phalanges

-5 digits, #1-5 thumb to pinky

-each digit has one metacarpal

-digits 2-5 have 3 phalangles: proximal, middle, distal

-digit 1 (pollex) has 2 phalanges: proximal and distal

Pelvis

hip bone + sacrum + coccyx

attaches lower limbs to the trunk

less free movement

Ossa coxae

hip bones

3 bones: ilium (elephant ear), ischium (hollow circle), pubis (bone above ischium)

acetabulum of pelvis

A concave surface of the pelvis that articulates with the head of the femur and inserts into the pelvis to form the hip joint.

Ilium

- crest is superior ridge of bone

- greater sciatic notch allows passage of sciatic nerve to lower limb

Ischium

the curved bone forming the base of each half of the pelvis.

ischial tuberosities are the "sit bones"

pubis

along with the ischium contributes to obturator foramen

pelvic inlet

space between pelvic and abdominal cavities

pelvic brim

edge of pelvic inlet

pelvic outlet

Inferior opening defined by ischial tuberosities, etc. (this is the bony feature you sit on).

The size of this outlet is important for a successful birth.

Male pelvis

somewhat narrower

pelvic inlet is more heart shaped

female pelvis

wider and shallower

wider angle of sacrum and coccyx

lower limbs

carries entire body weight

bones are thicker and stronger than the upper limbs

femur

thigh bone, largest and strongest bone in the body

femur head

smooth, rounded proximal end of the femur; articulates with acetabulum

Femur Greater and Lesser Trochanter

sites of muscle attachments

femur lateral and medial condyles

articulate with the tibula

are the more raised parts of these condyles

linea aspera of femur

ridge along the posterior diaphysis of the bone

used for muscle attachement

patellar surface of femur

patella articulates with femur here

patella

sesamoid bone (formed w connective tissue) encolosed in the tendon on the quadriceps femoris muscles

protects knee joint and improves leverage of the quadriceps muscles

kneecap

tibia

shin bone, medial to fibula

receives weight of body and transmits to foot

distal end is flattened for articulation with talus; medial malleolus projects to form ankle bone

medial and lateral condyles of tibia

articulate with the condyles of the femur

diaphysis of tibia

triangular with a sharp anterior border

fibula

thin lateral leg bone

head on superior end, lateral malleolus in inferior end (ankle bone)

DOES NOT BEAR WEIGHT

ankle fractures

- common in sports, skiing, running

- typically the result of rolling or twisting

- ligaments crossing the joint are often so strong that they remain intact but the bones fracture

Foot

function: supports body weight, acts as a lever for moving the body

7 tarsal bones

5 metatarsals

14 phalanges

hallux = big toe

Tarsals

ankle bones, 7

talus articulates with tibia and fibula superiorly and calcaneus inferiorly

calcaneus is the heel. achilles tendon attaches to posterior surface, allows extension of foot

metatarsals and phalanges

bones of the forefoot, 5

1st at base of big toe, largest, helps support weight of body

3 phalanges for each digit 2-5, ordered proximal, middle, distal

hallux (big toe) doesn't have middle phalanx

Arches of foot

medial longitudinal, lateral longitudinal, transverse

joints

support and movement

bones articulate at joints

skeletal muscles CROSS over joints in order to achieve movement

more mobile = less stable

classified by function OR structure

fibrous joints

consists of inflexible layers of dense connective tissue, holds the bones tightly together

immovable

cartilaginous joints

bones held together by cartilage

slightly moveable usually

Synovial joints

connected at a joint cavity within a capsule

freely movable usually

synchondrosis joint

A type of cartilaginous joint

bones joined by hyaline cartilage

symphyses joint

type of cartilaginous joint

fibrocartilage between articulating bones

synovial joints

freely movable joints that contain a fluid-filled joint capsule

typical synovial joints

Articular (fibrous) capsule -2 parts: outer fibrous layer continuous with periosteum, inner synovial membrane that secretes synovial fluid.

Joint (articular) cavity - space filled with synovial fluid

Synovial fluid - liquid in joint cavity and cartilages. Provides lubrication.

Articular (hyaline) cartilage - absorbs forces on the joint, protects bone

Ligaments- Connect bone to bone, strengthen joint. Can be internal or external to articular capsule.

Joints do have a blood supply and they are innervated too!

bursae

saclike structure with synovial fluid, reduce friction

tendon sheaths

wraps around tendon

plane joint

allows only gliding movement of bones

ex: carpal and tarsal bones

hinge joints

allows flexion and extension

ex: elbow joints, interphalangeal joints, knee joints

pivot joints

allows rotation

ex: proximal radioulnar joints, atlantoaxial joint

condylar joints

one bone has a convex surface, the other bone has a concave surface

found in the metacarpophalangel joints

ball and socket joints

very flexible; allows flexion/extension & adduction/abduction & rotation

ex: shoulder joints, hip joints

The knee

largest and most complex joint

usually acts as a hinge, can rotate slightly

condylar joint lateral/medial

acts as hinge joint

both femur and tibia have 2 condylar surfaces

Lateral Collateral Ligament (LCL)

connects femur to fibula

Medial Collateral Ligament (MCL)

connects tibia and femur

Anteior Cranial Fossa

deep within capsule and cross, so called cruciate ligaments

Posterior Cruciate Ligament (PCL)

deep within capsule and cross, so called cruciate ligaments

menisici of the knee

made of fibrocartilage, helps even out the weight distribution and stabilize the joint. prevent side-to side rocking of the femur on the tibia