13. MUSCULOSKELETAL SYSTEM

Musculoskeletal system: The musculoskeletal system includes the bones, muscles

and joints.

Bones: Bones provide the framework around which the body is constructed and

protect and support internal organs. Bones also assist the body in movement

because they are a point of attachment for muscles.

Joints: Joints are places at which bones come together.

Muscles: Muscles, whether attached to bones or to internal organs and blood

vessels, are responsible for movement.

Orthopedists: Physicians who treat bone and joint disease.

Rheumatologists: Physicians who primarily treat joint diseases.

Chiropractors: They use physical means to manipulate the spinal column, believing

that disease is caused by pressure on nerves.

Osseous tissue: Bones are complete organs composed chiefly of connective tissues

called osseous tissue. Osseous tissue consists of a combination of osteocytes (bone

cells), dense connective tissue strands known as collagen, and intercellular calcium

salts.

Cartilaginous tissue: During fetal development, the bones of the fetus are

composed of cartilaginous tissue, which resembles osseous tissue but is more flexible

and less dense because of a lack of calcium salts in its intercellular spaces.

Ossification: The gradual replacement of cartilage and its intercellular substance by

immature bone cells and calcium deposits is ossification.

Osteoblasts: Osteoblasts are the immature osteocytes that produce the bony tissue

that replaces cartilage during ossification.

Osteoclasts: They are large cells that function to reabsorb, or digest, bony tissue.

Osteoclasts digest bone tissue from the inner sides of bones and thus enlarge the

inner bone cavity so that the bone does not become overly thick and heavy.

Calcium and phosphorus: The formation of bone depends largely on a proper

supply of calcium and phosphorus to the bone tissue. These minerals must be taken

into the body along with a sufficient amount of vitamin D.

Vitamin D: Vitamin D helps calcium to pass through the lining of the small intestine

and into the bloodstream.

Structure: There are 206 bones of various types in the body.

Long bones: Long bones are found in the thigh, lower leg and upper and lower arm.

These bones are very strong, are broad at the ends where they join with other bones

and have large surface areas for muscle attachment.

Short bones: Short bones are found in the wrist and ankle and are small with

irregular shapes.

Flat bones: Flat bones are found covering soft body parts. They are the shoulder

blades, ribs, and pelvic bones.

Sesamoid bones: They are small, rounded bones resembling a sesame seed in

shape. They are found near joints, and they increase the efficiency of muscles near a

particular joint. The kneecap is the largest example of a Sesamoid bone.

Diaphysis: The shaft of middle region of a long bone.

Epiphysis: Each end of a long bone is called an epiphysis.

Epiphyseal plate: They represents an area of cartilage tissue that is constantly

being replaced by new bone tissue as the bone grows, its commonly known as the

growth plate.

Metaphysis: It is the flared portion of the bone; it lies between the epiphysis and

the diaphysis.

Periosteum: The periosteum is a strong, fibrous, vascular membrane that covers

the surface of bones, except at the ends of the epiphyses. It has an extensive nerve

supply.

Articular cartilage: The ends of long bones and the surface of any bone that meets

another bone to form a joint are covered with articular cartilage. It cushions the joint

and allows it to move smoothly and efficiently.

Cortical bone (compact bone): It is a layer of hard, dense bone that lies under

the periosteum in all bones and lies chiefly around the diaphysis of long bones.

Haversian canals: Within the cortical bone is a system of small canals containing

blood vessels that bring oxygen and nutrients to the bone and remove waste

products such as carbon dioxide is called Haversian canals.

Medullary cavity: Cortical bone is tunneled out in the central shaft of the long

bones by a medullary cavity that contains yellow bone marrow.

Cancellous bone: It is called spongy or trabecular bone is much more porous and

less dense than cortical bone.

Trabeculae: The mineral matter in the cancellous bone is laid down in a series of

separated bony fibers that make up a spongy latticework. These interwoven fibers

are called trabeculae.

Red bone marrow: Spaces in cancellous bone contain red bone marrow. This

marrow, as opposed to yellow marrow, which is fatty tissue, is richly supplied with

blood and consists of immature and mature blood cells in various stages of

development.

Bone processes: They are enlarged areas that extend out from bones to serve as

attachment for muscles and tendons.

Bone head: It is the rounded end of a bone separated from the body of the bone by

a neck; usually covered by articular cartilage.

Greater trochanter: It is the large process on the femur for attachment of tendons

and muscle.

Lesser trochanter: It is the smaller process.

Tubercle: It is the rounded process on many bones for attachment of tendons and

muscles.

Tuberosity: It is a small, rounded elevation on a bone.

Condyle: It is the rounded, knuckle-like process at the joint; usually covered by

articular cartilage.

Fossa: It’s a shallow cavity in or on a bone.

Foramen: It’s an opening for blood vessels and nerves.

Fissure: It’s a narrow, deep, slit-like opening.

Sinus: It’s a hollow cavity within a bone.

Cranium: The bones of the cranium protect the brain and structures related to it,

such as the sense organs.

Sutures: The cranial bones join each other at joints called sutures.

Fontanelles: The cranial bones of a newborn child are not completely joined. These

are gaps of unossified tissue in the skull at birth. These soft spots are called

Fontanelles.

Frontal bone: Forms the forehead and the roof of the bony sockets that contain the

eyes.

Parietal bone: The two bones that form the roof and upper part of the sides of the

cranium.

Temporal bone: The bones that form the lower sides and base of the cranium. Each

bone encloses an ear and contains a fossa for joining with the mandible.

Temporomandibular joint: TMJ is the area of connection between the temporal

and mandibular bones.

Mastoid process: It’s a round process of the temporal bone behind the ear.

Styloid process: It projects downward from the temporal bone.

Occipital bone: It forms the back and base of the skull and joins the parietal and

temporal bones, forming a suture.

Foramen magnum: The inferior portion of the occipital bone has an opening called

foramen magnum through which the spinal cord passes.

Sphenoid bone: The bat-shaped bone that extends behind the eyes and forms part

of the base of the skull.

Sella turcica: It is a depression in the sphenoid bone in which the pituitary gland is

located.

Ethmoid bone: The thin, delicate bone that supports the nasal cavity and forms

part of the orbits of the eyes.

Facial bones: All of the facial bones except one are joined together by sutures, so

they are immovable. The mandible is the only facial bone capable of movement. This

ability is necessary for activities such as mastication and speaking.

Nasal bones: The two slender bones that support the bridge of the nose. They join

with the frontal bone superiorly and form part of the nasal septum.

Lacrimal bones: The two, small, thin bones located at the corner of each eye. The

lacrimal bones contain fossae for the lacrimal gland and canals for the passage of the

lacrimal duct.

Maxillary bones: The two large bones that compose the massive upper jawbones.

They are joined by a suture in the median plane.

Cleft palate: If the two maxillary bones do not come together normally before birth,

the condition is known as cleft palate.

Mandibular bone: The lower jawbone. The mandible joins the skull at the region of

the temporal bone, forming the temporomandibular joint on either side of the skull.

Alveoli: Both the maxilla and the mandible contain the sockets called alveoli in

which the teeth are embedded.

Zygomatic bones: The two bones, one on each side of the face, that form the high

portion of the cheek.

Vomer: The thin, single, flat bone that forms the lower portion of the nasal septum.

Vertebral column: The vertebral column is composed of 26 bone segments called

vertebrae that are arranged in five divisions from the base of the skull to the

tailbone.

Intervertebral disks: The vertebrae are separated by pads of cartilage called

intervertebral disks.

Cervical vertebrae: The first seven bones of the vertebral column, forming the

bony aspect of the neck are the cervical vertebrae. These vertebrae do not articulate

with the ribs.

Thoracic vertebrae: The second set of 12 vertebrae is known as the thoracic

vertebrae. These vertebrae articulate with the 12 pairs of ribs.

Lumbar vertebrae: The third set of five vertebral bones is the lumbar vertebrae.

They are the strongest and largest of the backbones. Like the cervical vertebrae,

these bones do not articulate with the ribs.

Sacral vertebrae: The sacral vertebrae are five separate bones that fuse in a young

child. In an adult, the sacrum is a slightly curved, triangularly shaped bone.

Coccyx: The coccyx is the tailbone, and it is a fused bone, having been formed from

4 small coccygeal bones.

Vertebral body: A vertebra is composed of an inner, thick, round anterior portion

called the vertebral body. Between the body of one vertebra and the bodies of the

vertebrae lying beneath and above is an intervertebral disk.

Spinous process: The posterior portion of a vertebra consists of a single spinous

process.

Transverse process: It is present one on either side of the spinous process with a

bar like lamina on either side.

Neural canal: The neural canal is the space between the vertebral body and the

vertebral arch through which the spinal cord passes.

Clavicle: collar bone; a slender bone, ventrally, one on each side, connecting the

breastbone to each shoulder blade.

Scapula: shoulder blade; two flat, triangular bones, one on each dorsal side of the

thorax.

Acromion: The extension of the scapula that joins with the clavicle to form a joint

above the shoulder is called the Acromion. The joint formed by these two bones is

known as acromioclavicular joint.

Sternum: breastbone: a flat bone extending down the midline of the chest. The

uppermost part of the sternum articulates on the sides with the clavicle and ribs, and

the lower, narrower portion is attached to the diaphragm and abdominal muscles.

Xiphoid process: The lower portion of the sternum.

Manubrium: The upper portion of the sternum.

Ribs: There are 12 pairs of ribs.

Costal cartilage: The first 7 pairs join the sternum anteriorly through cartilaginous

attachments called costal cartilages.

True ribs: Ribs 1 to 7 are called true ribs. They join with the sternum anteriorly and

with the vertebral column in the back.

False ribs: Ribs 8 to 10 are called false ribs. They join with the vertebral column in

the back but join the 7th rib anteriorly instead of attaching to the sternum.

Floating ribs: Ribs 11 and 12 are the floating ribs because they are completely free

at their anterior ends.

Humerus: Upper arm bone; the large head of the Humerus is rounded and joins

with the glenoid fossa of the scapula to form the shoulder joint.

Ulna: medial lower arm bone; the proximal bony process of the ulna at the elbow is

called the olecranon. The olecranon is the bony point of the elbow when the elbow is

bent.

Radius: lateral lower arm bone.

Carpals: wrist bones there are two rows of four bones in the wrist.

Metacarpals: the five radiating bones in the fingers. These are the bones of the

palm of the hand.

Phalanges: finger bones. Each finger (except the thumb) has three phalanges; a

proximal, a middle and a distal phalanx. The thumb has only two phalanges: a

proximal and a distal phalanx.

Pelvic girdle: pelvis. This collection of bones supports the trunk of the body and

articulates with the femur to form the hip joint.

Ilium: The ilium is the uppermost and largest portion. Dorsally, the two parts of the

ilium do not meet. Rather, they join the sacrum on either side to form the sacroiliac

joints.

Iliac crest: The superior part of the ilium is the iliac crest. It is filled with red bone

marrow and serves as an attachment for abdominal wall muscles.

Ischium: The Ischium is the posterior part of the pelvis. The Ischium and the

muscles attached to it are what you sit on.

Pubis: The pubis is the anterior part of the pelvis.

Pubic symphysis: The two pubic bones join by way of a cartilaginous disk. This

area is called the pubic symphysis.

Pelvic cavity: The region within the ring of bone formed by the pelvic girdle is the

pelvic cavity. The rectum, sigmoid colon, bladder and female reproductive organs lie

within the pelvic cavity.

Femur: thigh bone; this is the longest bone in the body.

Acetabulum: rounded depression, or socket in the pelvis which joins the femur,

forming the hip joint.

Patella: kneecap; this is a small, flat bone that lies in front of the articulation

between the femur and one of the lower leg bones called the tibia. It is a Sesamoid

bone surrounded by protective tendons and held in place by muscle attachments.

Together with the femur and the tibia, it forms the knee joint.

Tibia: Largest of two bones of the lower leg; the tibia runs under the skin in the

front part of the leg. It joins the femur and patella proximally.

Medial malleolus: At the distal end, the tibia forms a flare that is the bony

prominence at the inside of the ankle.

Fibula: Smaller of two lower leg bones; this thin bone, well hidden under the leg

muscles, runs parallel to the tibia.

Lateral malleolus: At the distal end, the fibula forms a flare which is the bony

prominence on the outside of the ankle.

Ankle joint: The tibia, fibula and the talus come together to form the ankle joint.

Tarsals: bones of the hind part of the foot; these seven short bones resemble the

carpal bones of the wrist but are larger.

Calcaneus: It is the largest of the tarsal bones and also is called the heel bone.

Talus: The talus is one of the three bones that form the ankle joint.

Metatarsals: bones of the midfoot; there are five metatarsal bones, which are

similar to the metacarpals of the hand. Each leads to the phalanges of the toe.

Phalanges of the toes: bones of the forefoot; similar to the hand, there are two

phalanges in the big toe and three in each of the other toes.

Collagen: Dense, connective tissue protein strands found in bone and other tissues.

Kyphosis: The term indicates a hump on the back.

Laminectomy: An operation often performed to relieve the symptoms if

compression of the spinal cord or spinal nerve roots. It involves removal of the

lamina and spinous process.

Lordosis: The normal anterior curvature of the lumbar spine becomes exaggerated.

Osteogenesis imperfecta: It is a genetic disorder involving defective development

of bones; which are brittle and fragile; fractures occur with the slightest trauma.

Scoliosis: The spinal column is bent abnormally to the side.

Spondylosis: Degeneration of the intervertebral disks in the cervical, thoracic and

lumbar regions. Signs and symptoms include pain and restriction of movement.

Spondylolisthesis: The forward slipping of a vertebra over a lower vertebra.

Osteomalacia: A condition in which vitamin D deficiency leads to decalcification of

bones; known as rickets in children.

Osteoporosis: Loss of bony tissue with decreased mass of bone.

Ewing sarcoma: Malignant bone tumor.

Exostosis: Bony growth arising from the surface of bone.

Fracture: Traumatic breaking of a bone.

Closed fracture: A closed fracture means that the bone is broken but there is no

open wound in the skin.

Open fracture: An open fracture means that the bone is broken and a fragment of

bone protrudes through an open wound in the skin.

Pathologic fracture: A pathologic fracture is caused by disease of the bone such as

tumor or infection, making it weak.

Crepitus: Crepitus is the crackling sound produced when ends of bones rub each

other or rub against roughened cartilage.

Colles fracture: occurs near the wrist joint at the lower end of the radius.

Comminuted fracture: bone is splintered or crushed into several pieces.

Simple fracture: A simple fracture means that a bone breaks in only one place and

it therefore not comminuted.

Compression fracture: bone is compressed; often occurs in vertebrae.

Greenstick fracture: bone is partially broken; it breaks on one surface and only

bends on the other, as when a green stick breaks; occurs in children.

Impacted fracture: one fragment is driven firmly into the other.

Reduction: It is the restoration of the bone to its normal position.

Closed reduction: A closed reduction is manipulative reduction without a surgical

incision.

Open reduction: In an open reduction, an incision is made into fracture site.

Cast: A case is applied to fractures to immobilize the injured bone.

ORIF: The abbreviation ORIF means open reduction/internal fixation. Often this

involves insertion of metal plates, screws, rods or pins to stabilize the bone.

Osteogenic sarcoma: Malignant tumor arising from bone.

Osteomyelitis: Inflammation of the bone and bone marrow secondary to infection.

Talipes: Congenital abnormality of the hindfoot (involving the talus).

Synovial joints: Freely movable joints are called synovial joints.

Joint capsule: composed of fibrous tissue.

Ligaments: thickened fibrous bands of connective tissue anchor one bone to

another and thereby add considerable strength to the joint capsule.

Synovial membrane: It lies under the joint capsule and lines the synovial cavity

between the bones.

Synovial cavity: It is filled with a special lubricating fluid produced by the synovial

membrane.

Synovial fluid: It contains water and nutrients that nourish as well as lubricate the

joints so that friction on the articular cartilage is minimal.

Bursae: Bursae are closed sacs of synovial fluid lined with a synovial membrane and

are located near but not within a joint.

Ankylosis: A fusion of bones across a joint space by either bone tissue or growth of

fibrous tissue.

Arthroplasty: Replacement Arthroplasty is a replacement of one or both bone ends

by prosthesis of metal or plastic.

Hydrarthrosis: Synovial fluid collects abnormally in the joint.

Achondroplasia: This is an inherited condition in which the bones of the arms and

legs fail to grow to normal size because of a defect in cartilage and bone formation.

Dwarfism results, with short limbs and a normal-sized head and trunk.

Chondromalacia: A Chondromalacia patella is a softening and roughening of the

articular cartilaginous surface of the kneecap, resulting in pain, a grating sensation

and mechanical catching behind the patella.

Arthrodesis: Bones are fused across the joint space by surgery. This operation is

performed when a joint is very painful, unstable, or chronically infected.

Spinal Stenosis: Narrowing of the neural canal or nerve root canals in the lumbar

spine.

Ankylosing spondylitis: Chronic, progressive arthritis with stiffening of joints,

primarily of the spine.

Gouty arthritis: Inflammation and painful swelling of joints caused by excessive

uric acid in the body.

Osteoarthritis: Progressive degenerative joint disease characterized by loss of

articular cartilage and hypertrophy of bone at articular surfaces.

Rheumatoid arthritis: Chronic disease in which joints become inflamed and painful.

It is believed to be caused by an immune reaction against joint tissues, particularly

against the synovial membrane.

Bunion: Abnormal swelling of the medial aspect of the joint between the big toe and

the first metatarsal.

Carpal tunnel syndrome: Compression of the median nerve as it passes between

the ligament and the bones and tendons of the wrist.

Dislocation: Displacement of a bone from its joint.

Ganglion: A fluid-filled cyst arising from the joint capsule or a tendon in the wrist.

Herniation of intervertebral disk: Abnormal protrusion of a fibrocartilaginous

intervertebral disk into the neural canal or spinal nerves.

Lyme disease: A recurrent disorder marked by severe arthritis, myalgia, malaise

and neurologic and cardiac symptoms.

Sprain: Trauma to a joint with pain, swelling, and injury to ligaments.

Systemic lupus erythematosus: Chronic inflammatory autoimmune disease

involving joints, skin, kidneys, nervous system, heart and lungs.

Striated muscles: Striated muscle makes up the voluntary or skeletal muscles that

move all bones, as well as controlling facial expression and eye movements.

Fascia: Fibrous tissue that envelops and separated muscles is called fascia. It

contains the muscle’s blood, lymph and nerve supply.

Smooth muscles: Smooth muscle makes up the involuntary or visceral muscles

that move internal organs such as digestive tract, blood vessels, and secretory ducts

leading from glands. These muscles are controlled by the autonomic nervous system.

Cardiac muscles: Cardiac muscle is striated in appearance but is like smooth

muscle in its action. It movement cannot be consciously controlled.

Origin: The point of attachment of the muscle to the stationary bone is called the

origin.

Insertion: The point of junction of the muscle to the bone that moves is called the

insertion.

Flexion: Decreasing the angle between two bones; bending a limb.

Extension: Increasing the angle between two bones; straightening out a limb.

Abduction: Movement away from the midline of the body.

Adduction: Movement toward the midline of the body.

Rotation: Circular movement around an axis. Internal rotation is toward the midline

and external rotation is away from the midline.

Dorsiflexion: Decreasing the angle of the ankle joint so that the foot bends

backward. This is the opposite movement of stepping on the gas pedal when driving

a car.

Plantar flexion: Motion that extends the foot downward towards the ground as

when pointing the toes or stepping on the gas pedal.

Supination: As applied to the hand and forearm, the act of turning the palm

forward, or up.

Pronation: As applied to the hand and forearm, the act of turning the palm

backward, or down

Myasthenia gravis: Muscles lose strength because of a failure in transmission of

the nervous impulse from the nerve to the muscle cell.

Muscular dystrophy: A group of inherited disease characterized by progressive

weakness and degeneration of muscle fibers without involvement of the nervous

system.

Antinuclear antibody test: Detects an antibody present in serum of patients with

systemic lupus erythematosus.

Rheumatoid factor: Serum is tested for the presence of an antibody found in

patients with rheumatoid arthritis.

Serum calcium: Measurement of calcium level in serum.

Serum creatine kinase: Measurement of an enzyme in serum.

Arthrocentesis: Surgical puncture to remove fluid from the joint space.

Arthrography: Process of taking x-ray images after injection of contrast material

into the joint.

Arthroscopy: Visual examination of the inside of a joint with an endoscope and

television camera.

Bone density test: Low-energy x-ray absorption in bones of the spinal column,

pelvis, and wrist to measure bone mass.

Bone scan: Uptake of a radioactive substance is measured in bone.

Diskography: X-ray examination of cervical or lumbar intervertebral disk after

injection of contrast into nucleus pulposus.

Electromyography: Process of recording the strength of muscle contraction as a

result of electrical stimulation.

Muscle biopsy: Removal of muscle tissue for microscopic examination.

Polymyalgia rheumatica: It is a syndrome marked by aching and morning stiffness

in the shoulder, hip or neck for more than one month.