Chapter 7 Skeletal System (Part 2)

Vertebral Column

- 26 irregular bones form flexible support column
- surrounds and protects the spinal cord
- attachment site for ribs and muscles of back and neck
- fetus : 33 vertebrae > 5 fuse to form sacrum and 4 lowest fuse to form coccyx
- 28 inches in average adult

Vertebral Divisions

7 Cervical = C1 - C7
12 Thoracic = T1 - T12
5 Lumbar = L1 - L5
1 Sacrum = 5 fused
1 Coccyx = 4 fused

Scoliosis

- lateral curvature of the spine; most often in thoracic region
- may be present from birth or develop during growth spurt in adolescence
- more common in girls
- treated with braces (mild cases) and surgery
- idiopathic = no known cause

Kyphosis

hunchback - exaggerated dorsal curvature

Lordosis

swayback - exaggerated lumbar curvature; temporary lordosis in pregnant women

Vertebral Ligaments

- support vertebral column
- run as continuous bands down front and back surfaces of spine
- others : connect vertebrae to each other

Anterior Longitudinal Ligament

broad; prevents hyperextension of spine (bending too far backward)

Posterior Longitudinal Ligaments

weaker; prevents hyperflexion (bending too sharply forward)

Nucleus Pulposus

spherica; gelatinous - acts like a rubber ball

Annulus Fibrosus

strong collar of collagen fibers and fibrocartilage; limits expansion of nucleus pulposus

Intervertebral Discs

- act as shock absorbers
- flatten and bulge out in areas of compression

Herniated Disc

rupture of the annulus fibrosus and protrusion of nucleus pulposus - big

Spinous and Transverse Processes

attachment points for muscles that move vertebral column and ligaments that stabilize

Facets

smooth joint surfaces of articular processes covered with hyaline cartilage

Intervertebral Foramina

notches in superior and inferior articular processes, which allow spinal nerves to exit vertebral column

Shape of Cervical Vertebrae

- oval
- short spinous process, mostly bifid except atlas and C7
- with transverse foramen for vertebral arteries
- the spinous process of C7 is extra large, and can be felt through
the skin = vertebra prominens

Atlas and Axis

- no intervertebral disc between
- highly modified

Atlas

no body, no spinous process; superior articular facets receive occipital condyles of skull > lets you nod "yes"

Axis

typical except it has an odontoid process, has dens; pivot point of skull > lets you shake your head "no"

Dens

really body of atlas that gets fused to axis in embryo

Thoracic Vertebrae

- 12 thoracic vertebrae all articulate with ribs
- increase in size as you go down from T1-T12 to support more weight
- long spinous process that points sharply down

Lumbar Vertebrae

- sturdier structure due to increased weight bearing
- short, thick pedicle and lamina
- spinous process = hatchet - shaped

Sacrum

- triangular, 5 fused vertebrae
- articulates with L5 (top) and coccyx (below)
- articulates laterally (to the side) with hip bones > sacroiliac

Coccyx

- small triangular bone of 4 fused bones
- nearly useless
- slight support to pelvis

Thoracic Cage

- ribs, thoracic vertebrae, sternum, and costal cartilages
- Functions:
- protect thoracic and upper abdominal viscera
- support shoulder girdle and upper limbs
- play role in breathing

Ribs

- usually 12 pairs
- first 7 are true ribs
- last 5 are false ribs
- first 3 false ribs attach to cartilages of 7th rib
- last 2 false ribs are floating ribs

True Ribs

join sternum directly by costal cart

False Ribs

cartilages do not reach sternum directly

Floating Ribs

no attachment to the sternum

Sternum

- 3 parts:
- manubrium, body, and xiphoid process
- may use sternal puncture to aspirate red marrow for diagnosis of disease

Manubrium

articulates with clavicles (collarbones) by facets on superior border

Xiphoid Process

projects down

Pectoral Girdle

- 4 parts: 2 clavicles and 2 scapula
- incomplete ring

Girdle

Incomplete Ring

open in back between scapula and separated in front by sternum

Clavicles

- elongated, s-shaped, slender
- brace scapulae to help hold shoulders in place;provide attachments for muscles of upper limbs, chest and back

Scapulae

- broad, triangular bones
- scapular spine divides into unequal portions
- 2 processes + depression
- acromion, coracoid, and glenoid

Acromion

tip of shoulder, articulates with clavicle; attachment for muscles of upper limb

Coracoid

curves anteriorly; also attachment site for upper limb and chest muscles

Glenoid Cavity

- depression between two processes for head of humerus

Upper Limb

- attachments for muscles
- function as levers that move limb parts
- Bones are: humerus, radius, ulna, carpals, metacarpals, phalanges

Humerus

- head fits into glenoid cavity of scapula
- greater and lesser tubercles for muscle attachment
- anatomical vs. surgical neck
- deltoid tuberosity

Deltoid Tuberosity

attachment site for deltoid muscle to raise arm

Radius and Ulna

- connected to each other via interosseous membrane + articulations at each end
- in an anatomical position, radius is on the thumb side
- bones cross each other when palms are facing the rear > form an "X"

Ulna

- Acronym : over the counter
- longer than the radius; top looks like the letter "U"
- olecranon process, trochlear notch, and coronoid process

Trochlear Notch

wrenchlike opening; articulates with humerus

Olecranon Process and Coronoid Process

muscle attachments

Radius

- the thumb side of the forearm, looks like a circle at top and circles have radiuses
- head articulates with humerus and radial notch
- radial tuberosity and styloid process

Radial Tuberosity

attachment for biceps brachii

Styloid Process

wrist ligament attachment

Hand

- wrist, palm, 5 fingers
- wrist = 8 small carpal bones in a 2x4
- 5 metacarpals, thumb #1-5
- Phalanges = finger bones
- proximal, middle, distal phalanx (except the thumb
does not have a middle phalanx)

Pelvic Girdle

- 2 coxal bones (os coxa) that articulate with each other anteriorly; with sacrum posteriorly
- each os coxa has 3 parts : ilium, ischium, and pubis
- the cartilage between the 2 pelvic bones is there so they don't rub together and so it can stretch when women give

Ilium

top portion, shaped like a fan

Ischium

"L" shaped, ischial tuberosity

Pubis

anterior lower part

Symphysis Pubis

the midline when the 2 pubic bones are fused

Lower Limb

- femur, tibia, fibula, tarsals, metatarsals, and phalanges

Femur

- longest bone in body
- lateral and medial condyles
- patella located on tendon that passes in front of knee

Lateral and Medial Condyles

articulate with tibia

Patella

kneecap

Tibia

- sort of looks like a "T", bigger than fibula
- shinbone
- tibial tuberosity and medial malleolus

Tibial Tuberosity

- attachment for patellar ligament

Medial Malleolus

on inner ankle, attachment for ligaments

Fibula

- lateral side of lower leg
- does not bear body weight
- does not enter into knee joint
- lateral malleolus protrudes on lateral side = outer ankle

Foot

- ankle, instep, 5 toes
- tarsals, metatarsals, and phalanges

Tarsals

7 tarsal bones (includes calcaneous)

Calcaneous

heel bone

Metatarsals

5 elongated metatarsals; heads of these bones form ball of foot; ligament arches from springy base for body

Phalanges

same arrangement as fingers

Fibrous Joints

- resist movement
- no joint cavity
- sutures of skull
- between tibia and fibula - allows "give", but no true
movement
- connect teeth to sockets

Gomphosis

connect teeth to sockets

Cartilaginous Joints

- allow some movement
- no joint cavity
- growth plates in children
- intervertebral discs

Synovial Joints

- fluid filled joint cavity
- allow a range of movement
- the majority of joints in the body
- structure
- movements
- types

Structures of Synovial Joints - Synovial Fluid

reduces friction, ~ egg whites

Structures of Synovial Joints - Cavity

filled with synovial fluid

Structures of Synovial Joints - Articular Cartilage

hyaline, reduce friction

Structures of Synovial Joints - Articular Capsule

membrane surrounding cavity

Structures of Synovial Joints - Reinforcing Ligaments

good nerve supply to help maintain joint stability

Structures of Synovial Joints - Bursae

little bags of synovial fluid that let tendons slide over joint; act like ball bearings

Structures of Synovial Joints - Tendon Sheaths

hot dog bun shaped bursa that wraps around tendon

Structures of Synovial Joints - Meniscus

in some synovial joints (knee), a pad of fibrocartilage that separates 2 articulating bones, cushion between 2 bones, looks like a sideways 8

Movements of Synovial Joints - Flexion

decreases the angle between bones

Movements of Synovial Joints - Extension

increases the angle between bones

Movements of Synovial Joints - Adduction

movement of limb toward body

Movements of Synovial Joints - Abduction

movement of limb away from body

Movements of Synovial Joints - Supination

hand with palm anterior (anatomical position)

Movements of Synovial Joints - Pronation

hand with palm posterior

Movements of Synovial Joints - Planter Flexion

curling foot inferiorly

Movements of Synovial Joints - Dorsoflexion

curling foot superiorly

Movements of Synovial Joints - Rotation

turning of bone around its own long axis; may be lateral or medial

Movements of Synovial Joints - Opposition

movement used to touch thumb to tips of fingers of same hand

Movements of Synovial Joints - Circumduction

drawing a circle with distal end of limb

Types of Synovial Joints - Ball and Socket

- head of one bone articulates with the fossa of a second bone
- allows movement and rotation
- EX: humerus and scapula, femur and acetabulum

Types of Synovial Joints - Condylar

- concave oval fits into a convex oval
- 2 dimensional movement but no rotation
- EX: metacarpals and phalanges

Types of Synovial Joints - Pivot

- allows rotation
- EX: radius and ulna, atlas and axis

Types of Synovial Joints - Hinge

- the cylinder shape of one bone fits into the trough of a second bone
- motion in a single plane
- EX: humerus and ulna

Types of Synovial Joints - Plane

- limited number; short slipping movements
- bones of wrist and ankle

Types of Synovial Joints - Saddle

- like condylar, but greater movement
- used to twiddle thumbs

Joint Disorders - Dislocation

- bone forced out of alignment
- common in shoulder, elbow (nursemaids elbow)

Joint Disorders - Arthritis > Osteoarthritis

- degenerative condition of articular cartilage from wear
- causes pain, stiffness, swelling
- treat with steroids, glucosamine, joint replacement