Chapter 4: Skeletal & Muscular System

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The skeletal system consists of ____ bones that make up the internal framework of the body, called the skeleton.

The Skeleton

Supports the body, protects internal organs, serves as a point of attachment for skeletal muscles for body movement, produces blood cells, and stores minerals

• Bones

• Joints

The primary structures that compromise the skeletal system:

Bone

Each ____ in the human body is a unique organ that carries its own blood supply, nerves, and lymphatic vessels

Skeleton

Bones forming framework for body; Site for skeletal muscles attachments

Bone Marrow

Soft tissue found inside cavities in bones; Site for producing blood cells

Joints

Point at which two bones meet and are held together by ligaments; Provides flexibility

Ligaments

Very strong bands of connective tissue that bind bones together at a joint

Movement

The skeleton, joints, and muscles work together to produce ______

Osseous Tissue

Another name for bone; bony tissue; One of the hardest materials in the body

Ossification

Process of bone formation

Cartilage

First model of the skeleton formed in the fetus; Strong, flexible connective tissue found in several locations in the body, such as covering ends of bones in synovial joint, nasal septum, external ear, eustachian tube, larynx, trachea, bronchi, and intervertebral disks

Osteoblasts

Immature bone cells; Gradually replace the cartilage with bone

Osteocytes

Mature bone cells; In a fully adult bone, the osteoblasts have matured into _____ that work to maintain the bone

Calcium (Ca) / Phosphorous (P)

The formation of strong bones is greatly dependent on an adequate supply of minerals such as _____ and _____.

Remodeling

Gradual replacement process of old bone with new bone

Osteoclasts

Breaks down old bone as osteocytes continuously make new bone

In a growing child, osteocyte activity, ______ osteoclast activity.

Outpaces

In an adult, the activity of osteocytes and osteoclasts are roughly ______.

Equal

The bones of an adult completely replace themselves every ____ years.

10

• Long Bones

• Short Bones

• Flat Bones

• Irregular Bones

Types of bones:

Long Bones

Type of bone that is longer than it is wide; Examples include femur, humerus, and phalanges

Short Bones

Type of bones that is roughly cubed shaped; Examples include the carpals and tarsals

Flat Bones

Type of bone with a thin flattened, plate-shape; Examples include sternum, scapula, ribs, and pelvic bones

Irregular Bones

Type of bone having an irregular shape; Ex: Vertebrae

Long

The majority of bones in the human body are _____ bones.

End

Long bones have similar structure with a central shaft (diaphysis) that widens at each _____, which is called an epiphysis.

Diaphysis

Central shaft portion of a long bone

Epiphysis

Wide ends of a long bone

Articular Cartilage

Layer of cartilage covering ends of bones; Acts as cushion and prevents bones in joint from rubbing directly on each other

Articular

Each epiphysis is covered by a layer of _____ cartilage.

Periosteum

Thin connective tissue membrane that covers most bones; Contains numerous blood vessels, nerves and lymphatic vessels

Cortical / Compact Bone

Hard exterior surface bone; Pertaining to cortex or outer layer

Cancellous

Bony tissue found inside bone; Contains cavities that hold red bone marrow; Sponge-like appearance; Also called spongy bone

Red Bone Marrow

Tissue that manufactures most blood cells; Found in cancellous bone cavities

Medullary Cavity

Center of the diaphysis contains a large open cavity that extends length of shaft of long bone; Contains yellow bone marrow

Yellow

Early in life, the medullary cavity also contains red bone marrow, but as a person ages, the red bone marrow of the medullary cavity gradually converts to ______ bone marrow.

Yellow Bone Marrow

Located mainly in the center of diaphysis of long bones; Consists primarily of fat cells

Projects / Depressions

Bones have many ______ and ______; some are rounded and smooth in order to articulate with another bone in a joint. Others are rough to provide muscles with attachment points.

Process

General term for any bony projection

Operative

Then there are specific terms to describe the different shapes and locations of various processes. These terms are commonly used on _______ reports and in physicians’ records for clear identification of areas on the individual bones.

• Head

• Condyle

• Epicondyle

• Trochanter

• Tubercle

• Tuberosity

Some of the common bony processes include the following:

Head

Large, smooth, ball-shaped end on a long bone. It may be separated from the body or shaft of the bone by a narrow area called the neck.

Neck

(1) The cervical region of the body; (2) Narrow length of bone that connects ball of ball-and-socket joint to diaphysis of long bone

Condyle

Smooth, rounded portion at the end of a bone

Epicondyle

Projection located above or on a condyle

Trochanter

Refers to a large, rough process for the attachment of a muscle

Tubercle

Small, rough process that provides the attachment for tendons and muscles

Tuberosity

Large, rough process that provides the attachment for tendons and muscles

Sinus

Hollow cavity within a bone

Foramen

Smooth, round opening for nerves and blood vessels

Fossa

Shallow cavity or depression on the surface of a bone

Fissure

Slit-type opening

• Axial

• Appendicular

What are the two divisions of the human skeleton?

Axial Skeleton

These bones form the central axis for the whole body and protect many of the internal organs such as the brain, lungs, and heart; Includes bones in head, spine, chest, and trunk

• Cranium

• Facial Bones

The head or skull is divided into two parts consisting of the ______ and ______ bones

Cranium

Skull; Bones that form a protective covering over the brain

The cranium encases the brain and consists of:

• Frontal Bone

• Parietal Bones

• Occipital Bone

• Temporal Bones

• Sphenoid Bone

• Ethmoid Bone

Facial Bones

Skull bones that surround the mouth, nose, and eyes; Location where muscles for chewing and moving the head are attached to the cranial bones

• Mandible

• Maxilla

• Zygomatic Bones

• Vomer Bone

• Palatine Bone

• Nasal Bones

• Lacrimal Bones

The facial bones surround the mouth, nose, and eyes and include the:

Frontal Bone

Forehead bone of the skull (cranium)

Parietal Bones

Upper sides of cranium and roof of skull

Occipital Bone

Back and base of skull

Temporal Bones

Sides and base of cranium

Sphenoid Bone

Bat-shaped bone that forms part of the base of skull and floor and sides of eye orbit

Ethmoid Bone

Forms part of eye orbit, nose, and floor of cranium

Lacrimal Bones

Inner corner of each eye

Nasal Bones

Form part of nasal septum and support bridge of nose

Maxilla

Upper jaw

Mandible

Lower jawbone; only moveable bone of the skull

Zygomatic Bones

Cheekbones

Vomer Bone

Base of nasal septum

Palatine Bone

Hard palate roof of oral cavity and floor of nasal cavity

Hyoid Bone

Single U-shaped bone suspended in the neck between the mandible and larynx; Point of attachment for swallowing and speech muscles

• Vertebral Column

• Sternum

• Rib Cage

The trunk of the body consists of:

Vertebral Column

Part of axial skeleton; Column of 26 vertebrae that forms backbone and protects spinal cord; Divided into five sections; Also called spinal column

• Cervical Vertebrae

• Thoracic Vertebrae

• Lumbar Vertebrae

• Sacrum

• Coccyx

The Vertebral Column is divided into five (5) sections:

Cervical Vertebrae

(C1, C2, etc.); Seven vertebrae in neck region

Thoracic Vertebrae

(T1, T2, etc.); Twelve vertebrae in chest region with ribs attached

Lumbar Vertebrae

Five vertebrae in the low back region; in the small of back, about waist level

Sacrum

Five fused vertebrae that form large triangular-shaped flat bone in the upper buttock region

Coccyx

Tailbone, three to five very small vertebrae attached to sacrum; often become fused

Intervertebral Disk

Fibrous cartilage cushion between vertebrae; Located between each pair of vertebrae, from the cervical through the lumbar regions

Rib Cage

Formed by curved ribs extending from vertebral column around sides and attaching to sternum; Part of axial skeleton; Serves to provide support for organs, such as the heart and lungs; Also called chest cavity

12

The rib cage has ____ pairs of ribs attached at the back to the vertebral column

10

____ pairs of the ribs are also attached to the sternum in the front.

Floating

The lowest two pairs of the ribs are called ______ ribs and are only attached to the vertebral column.

Appendicular Skeleton

Consists of bones of upper and lower extremities, shoulder, and pelvis; These are the bones for the appendages or limbs and, along with the muscles attached to them, are responsible for body movement

• Pectoral Girdle

• Upper Extremities (UE)

• Pelvic Girdle

• Lower Extremities (LE)

The appendicular skeleton consists of the:

Pectoral Girdle

Consists of clavicle and scapula; Functions to attach upper extremities to axial skeleton

Clavical

Bone of Pectoral Girdle; Also called the collar bone

Scapula

Bone of Pectoral Girdle; Also called the shoulder blade

Upper Extremities (UE)

The arm

What do the bones of the upper extremity consist of?

• Humerus

• Ulna

• Radius

• Carpus

• Metacarpus

• Phalanges

Humerus

Upper arm bone in upper extremity

Ulna

Forearm bone on the thumb side in upper extremity

Radius

Forearm bone on little finger side in upper extremity

Carpus

Collective name for the eight (8) wrist bones in each upper extremity

Metacarpus

Collective name for the five (5) hand bones in each upper extremity

Phalanges

Finger bones in upper extremities; Toe bones in in lower extremities