Unit 2 Human Anatomy

Long bones

• longer than they are wide and serve as a lever

• Made up of diaphysis, epiphysis, and epiphyseal plate

Diaphysis

• long shaft of a long bone

• hollow cylinder

Epiphysis

area on the end of a long bone where a joint occurs

Epiphyseal plate

• hyaline cartilage that separates the diaphysis and epiphysis marrow cavities

• new cartilage cells born and old cartilage cells are replaced by bone → epiphyseal line appears when new cartilage cells stop proliferating and growth in length of long bone stops

Epiphyseal line (growth plate)

• when this appears, growth in length of the long bone is done

• dictated by growth hormones

Metaphysis

• area between the diaphysis and epiphysis

• where the growth plate lives

Yellow bone marrow

• hollow cavity in the diaphysis that is occupied with adipose tissue (fat)

• can be an energy reserve

• no longer produces blood

Red bone marrow

• at the epiphysis, and where blood cell production occurs (hemopoiesis)

• most commonly harvested from the pelvis for marrow donation

Periosteum

• connective tissue covering on the outside of long bones

• serves as place for muscle attachment

• only place with sensory nerves

Articular cartilage

• thin layer of hyaline cartilage covering the articular surface of a bone at a synovial joint

• reduces friction and eases joint movement

Compact (cortical) bone

• layer located on the outside of bones

• made up of osteons

Spongy (cancellous) bone

• bone with large spaces

• primarily located within the epiphysis

• where red bone marrow is

• made up of trabeculae

Matrix

• made up of organic (collagen) and inorganic (mineral salt) components

Collagen

• organic component

• makes bones flexible

Mineral salts

• inorganic component

• calcium and phosphates

• provide hardness to bone

Organic > inorganic

• bendy bones

• rickets/osteomalacia - bones bend with any force

Organic < inorganic

• brittle bones

• osteogenesis imperfecta

Osteon

• basic functional unit of compact bone

• made up of a central canal, lamellae, lacunae, and canaliculi

Central canal

contains the neurovasculature (arteries, nerves, and veins)

Lacunae

the canals forming a ring around the central canal where the osteoblasts live

Lamellae

• a ring of connective tissue around the central canal made up of lacunae

• 3 form concentric rings around the central canal

Canaliculi

• tunnels between the processes of neighboring osteoblasts

• gap junctions

Trabeculae

• seemingly random arrangement of spicules (“sticks”) in spongy bone

• arrangement determined by forces placed on the bone

Endochondral ossification

• produces most bones

• development of bone from a cartilage template

  • hyaline cartilage template becomes invaded by a blood supply

  • primary and secondary ossification centers form

  • blood carries osteoblasts and lays down matrix

Intramembranous ossification

• produces the flat bones of the skull, part of the mandible, and the clavicle

• develops within a fibrous sheet

• mesoderm becomes mesenchyme, which is invaded by osteoblasts that lay down osteoid tissue

• compact bone on the outside and spongy on the inside

Bone remodeling

• involves absorption of old bone and deposition of new bone

• reshapes bone in response to use and disuse and repairs microfractures

Fracture

caused when forces are greater than resistance

Fracture repair

1. hematoma formation

2. soft callus formation

3. hard callus formation

4. bone remodeling

Reduction

• realignment of bones

• open - placing screws, braces, or metal plates through surgery

• closed - manually easing bones back into alignment

Osteopenia

• when bone mass decreases from too few forces on the bone

• ex. bed rest

Hyperostosis

bone mass increases (too thick)

Osteoblasts > osteoclasts

• tearing down bone faster than it can be laid down

• osteoporosis

Skull bones

• made up of a layer of spongy bone surrounded by compact bone

• attached at joints called sutures

Sutures

joints that appear as seams on the surface of the skull

Paranasal sinuses

• spaces in four of the skull bones that surround the nasal cavity

• resonate sound

Frontal sinus

an air-filled space in the bone of the forehead

Anterior cranial fossa

where frontal lobe is located

Middle cranial fossa

where temporal lobe is located

Posterior cranial fossa

where cerebellum is located

Parietal bones

• form most of the cranial roof and part of its walls

• bordered by four sutures

Occipital bone

located in the rear of the skull

Occipital condyle

• articulate with the first bone of the spine

• small knob where the skulls rests on the vertebral column

• allows you to nod your head

Foreman magnum

• located in the occipital bone

• allows passage of the spinal cord and vertebral arteries into the cranial cavity

Temporal bone

forms the lower wall and part of the floor of the cranial cavity

Mandibular fossa

condyle where the mandible sits to form the temporomandibular joint

External acoustic meatus

a canal in the temporal bone that conveys sound waves to the eardrum

Mastoid process

• lump behind the ear

• filled with small air sinuses

Petrous

portion of the temporal bone where the inner ear is found

Sphenoid bone

• contacts every other cranial bone

• made up of a median body and greater and lesser wings

Sella turcica

saddlelike surface feature in the median body of the sphenoid bone

Sphenoidal sinuses

Ethmoid bone

• anterior cranial bone located between the eyes

Horizontal cribriform plate

full of pin holes that lead to the roof of the nasal cavity

Crista galli

median crest located on the cribriform plate

Vertical perpendicular plate

thin median plate that forms the superior two-thirds of the nasal septum

Mandible

supports the lower teeth and provides attachment for muscles of mastication and facial expression

Mandibular fossa

condyle where the mandible sits to form the TMJ

Maxilla

form the upper jaw and meet at the intermaxillary suture

Maxillary sinus

Zygomatic bones

form the angles of the cheeks, inferolateral to the eyes, and part of the lateral wall of each orbit

Zygomatic process

extends anteriorly to form part of the zygomatic arch

Vertebral column

made up of 7 cervical, 12 thoracic, 5 lumbar, 1 sacrum, and 1 coccyx

Intervertebral disc

• a cushion between adjacent vertebrae

• two parts: annulus fibrosus and nucleus pulposus

Nucleus pulposus

inner part of the intervertebral disc

Annulus fibrosis

outer part of the intervertebral disc made up of concentric rings of fibrous cartilage

Scoliosis

lateral curvature of the spin

Hyperkyphosis

hunchback

Hyperlordosis

swayback

Vertebra body

weight-bearing portion

Lamina and pedicles

portion that protects the spinal cord

Vertebral arch

composed of the pedicles and lamina that enclose the vertebral foramen

Intervertebral foramen

• between the superior and inferior pedicles

• spinal nerves leave the spinal cord through this

Vertebral foramen

vertebral arch and body enclose this

Spinous process

Transverse process

Superior articular processes

project upward from one vertebra

Inferior articular processes

project downward from one vertebra

Superior/inferior vertebral notches

Cervical vertebrae

• small and oval-shaped

• hole (foramen) in the transverse process for the artery ascending the neck

• fork-shaped spinous process

Thoracic vertebrae

• large and heart-shaped

• long transverse processes that have articular facets for the ribs

• long spinous process that points inferiorly

Lumbar vertebrae

• largest and kidney-shaped

• short transverse processes with no facets or foramina

• thick spinous processes that point posteriorly

Sacrum

• five fused vertebrae

• no intervertebral foramen

• spinal nerves come out through the anterior and posterior sacral foramina

Superior articular facet

articulates with the inferior articular facet and L5

Coccyx

5 fused coccygeal vertebrae, which form the end of the spine

Atlas

• C1

• superior articular facet that articulates with the occipital condyle

• atlantooccipital joint

Axis

• C2

• Inferior articular facet of the atlas articulates with the superior articular facet of the axis at the atlantoaxial joint

• responsible for head rotation

Bifid spinous processes

• spinous process is forked

• only found in cervical vertebrae

Thoracic (rib) cage

composed of 12 pairs of ribs and the sternum

Sternum

made up of the manubrium, body, and xiphoid process

Manubrium

• broad superior portion of the sternum

• suprasternal notch and sternal angle

Body

• longest part of the sternum

• articulates with the manubrium at the sternal angle

Xiphoid process

smaller, inferior end of the sternum

True ribs

ribs 1—7 which each have their own costal cartilage

False ribs

ribs 7—10 where the costal cartilage runs together

Floating ribs

ribs 11 and 12 which don’t have costal cartilage

Costal cartilage

hyaline cartilage that attaches each rib to the sternum

Intercostal space

• space between the ribs

• filled with intercostal muscles

Costal facet

unique to thoracic vertebrae to connect with the head of a rib

Coronal suture

Lambdoid suture