Skeletal System

Skeletal SystemIntroduction to Veterinary Science

The Musculoskeletal System

•The musculoskeletal system consists of two systems that work together to support the body and allow for movement of the animal:▫the skeletal system = bones, joints,

cartilage, and various connective tissues▫the muscular system = muscles and

various connective tissues

What is the function of bone?•Bone helps with:

▫Movement

▫Support

▫Protection

▫Blood cell formation

Bones• Bones start as cartilage and fibrous

membranes that harden into bone before birth.▫The formation of bone from fibrous tissue is

known as ossification. Osteoblasts produce bone

tissue Osteocytes maintain

bone tissue Osteoclasts break

or phagocytize bone tissue

Bones build up and break down throughout life and has ability to repair and heal.

Important Terms Related to the Skeleton

The skeleton can be divided into two parts

• Axial Skeleton

• Appendicular skeleton

Other Important Terms, Con't.• Joints—points where two or

more bones meet. Cartilage

protects the ends of bones provides a cushion

Other Important Terms, Con't.• Ligament—Tough band of connective

tissue connecting one bone to another.

• Tendon—Thick band of connective tissue that attaches muscle to bone.

Types of Bone

• Bone is one of the hardest tissues of the body

▫ Connective tissue▫ Only thing harder-tooth enamel

• Compact Bone—layer of protective hard bone tissue surrounding every bone

• Cancellous Bone—soft bone filled with many holes and spaces surrounded by hard bone.

Combining forms for Bone

•Oste/o•Oss/e•Oss/i

•Osteoarthritis•Ossification

Classification of bones

•Long bones•Short bones•Flat bones•Irregular Bones

Long Bone

•Long bones consist of a shaft, two ends, and a marrow cavity.▫Femur▫Humerus▫Tibia▫Radius

•Red bone marrow is hematopoietic and is found at the ends of long bones and in flat bones(hemato-blood/ -poietic pertaining to formation)▫Red bone marrow produces red blood cells,

white blood cells, platelets▫Yellow bone marrow replaces red bone marrow

(mostly fat cells)

•Flat bones - thin flat bones: pelvis, ribs, scapula, bones of the skull▫Flat bones are made up of a layer of spongy

bone between two thin layers of compact bone

•Short bone- cube shaped, no marrow▫Carpal bones▫Tarsal Bones

•Pneumatic bones- sinus containing bones (frontal)

Irregular Bones

•Vertebrae-make up the spine

•Sesamoid bones- small, embedded in a tendon:▫Dog: patella, fabellae (2)▫Horse: proximal sesamoids (2) and

navicular bone

FACT:

•The average dog has about 320 bones…134 in the axial skeleton-the skull has 50 flat bones!186 in the appendicular skeleton

The average horse has about 205 bones

Bones of the Axial Skeleton

The axial skeleton protects the major organs of the nervous, respiratory, and circulatory systems.

•Skull•Vertebrae•Ribs •Sternum

Cranium Bones and Face Bones

•Occipital•Parietal•Frontal•Temporal•Zygomatic Arch•Nasal•Incisive

parietal

frontal

Zyg

om

atic a

rch

Occipital bone

incisive

nasal

Short, Average, Long

Vertebral Column• The vertebral column supports the head and body and

provides protection for the spinal cord.• The vertebral column is comprised of individual bones

called vertebra.▫The combining forms for vertebra are spondyl/o and

vertebr/o.▫Vertebrae is the plural form.

Horse C7 T18 L6 S5 Cd 15-21Dog C7 T13 L7 S3 Cd 20Cat C7 T13 L7 S3 Cd 14-23

Parts of a Vertebra

•Vertebrae are divided into parts:▫ body▫ arch▫ lamina▫ vertebral foramen▫ processes

spinous process transverse process articular process

Other Axial Skeleton Parts

•Ribs▫ Combining form is cost/o.▫ Are flat bones▫ Attached by cartilage▫ Purpose to protect

•Sternum▫ Manubrium, body, xiphoid▫ sternebrae▫ xiphoid process (caudal-most sternebra)▫ Flat bones and cartiligenous

Make up the boundaries of the thoracic cavity (protects heart and lungs)

Bones of the Appendicular Skeleton

• The appendicular skeleton includes the bones of the front and hind limbs•Front Limb

• Scapula• Humerus• Radius• Ulna• Carpal bones• Metacarpal bones• Phalanges

•Hind Limb▫Pelvis▫Femur▫Tibia▫Fibula▫Tarsal bones▫Metatarsal bones▫Phalanges

The Appendicular Skeleton

•Front limb▫scapula▫clavicle▫humerus▫radius▫ulna▫carpal bones▫metacarpal bones

cannon bone in livestock▫Phalanges

Differ in dog, horse, ungulates (cloven hoof)

Forelimb

•Scapula(Ball and socket joint)

•Humerus•Radius and Ulna•Carpal Bones

▫Metacarpals▫Phalanges

Ball and Socket joint Scapula and Humerus – Point of Shoulder

“Elbow” joint

Hinge joint between Humerus and the Radius/ Ulna ANDPivot Joint

The Appendicular Skeleton

• Phalanx names:▫ Proximal = long pastern

bone in livestock▫ Medial = short pastern

bone in livestock▫ Distal = coffin bone in

livestock ▫ Distal in small animals

may be called the claw or nail. In cats the claw cannot be separated from the phalanx bone. Combining form

for claw or nail is onych/o.

Phalanges•Dog:

▫3 phalanges proximal, middle, distal

▫5 digits I-V Start medial to lateral Medial digit is digit I

(the dewclaw in dogs)

Phalanx

•Horse▫One digit (III)▫3 phalanx bones

Fetlock joint

Cloven hoof

•Cloven hoofed animals• Two digits (III-IV)• Three phalanx bones• Digits II and V are

vestiges• Distal phalanx is

encased in a hoof.

The Hind Limb

•Hind limb▫ pelvis▫ femur▫ patella▫ tibia▫ fibula▫ tarsal bones▫ metatarsal bones

cannon bone in livestock

▫ phalanges

Pelvic Bones

•The bones of the pelvis:▫ilium▫ischium▫pubis▫acetabulum—

bony part of the socket joint

Cat skeleton: Where is the Clavicle

Owl Skeleton

Horse Skeleton

Unlabeled Horse Skeleton

Veterinary Medicine of Bones

Bone problems – Pathological conditions

• Hip dysplasia• Invertebral disc disease

▫Herniated disc▫Ruptured disc▫ IVDD

• Osteochondrosis dissecans▫OCD

• OsteoarthritisDegenerative Joint Disease / DJD

• Spondylosis• Luxation and Subluxation (complete vs partial)

IVD – invertebral disc disease

•Can happen suddenly or slowly

•Can cause paralysis

•CT junction•TL junction•Breed

propensity•Treatment

Spondylosis

Osteochonditis Dissecans - OCD

Luxating Patella

Normal hip joint

Hip Joint = Coxofemoral jointSubluxation = femoral head slips in and out of acetabulum

Hip Dysplasia

FHO –Femoral Head Ostectomy

Fracture terminology

•Closed Fracture/ Simple•Open Fracture/ Compound•Manipulation/ Reduction-realignment of bone

• Immobilization-holding in a fixed position

•Crepitation-cracking sensation (felt and heard)

•Surgical Procedure:▫Osteotomy-cutting into a bone▫Ostectomy-removal of a bone –FHO

(Femoral Head Ostectomy)

Fractures

Comminuted fracture-cat radius and ulna

Femur Fracture and Repair

Femur- Pinned

Structures

• Bones are not smooth and have bumps, ridges, grooves,etc▫ Foramen-hole (Infraorbital foramen, magnum foramen,

obturator foramen)▫ Condyle-rounded projection ▫ Process-projection (spinous process, xiphoid process)▫ Aperture-opening▫ Canal – tunnel (Haversian Canal)▫ Crest - high projection or border projection (sagittal crest)▫ Fossa-trench or hollow depressed area (trochanteric

fossa of femur, supraspinatous fossa)▫ Head- major protrusion, round, spherical (femoral

head)▫ Lamina-thin, flat plate

More bumps, ridges and grooves▫ Sinus-space or cavity▫ Spine-sharp projection (spine of the scapula)▫ Sulcus-groove (gingival sulcus, radial sulcus on

humerus for radial nerve)▫ Suture-seam (skull)▫ Trochanter-broad flat projection (greater

trochanter/lesser trochanter on the femur)▫ Trochlea-pulley shaped structure in which other

structures pass or articulate (patella sits in a trochlea)▫ Tuberosity-projecting part (iliac tuberosity, ishiatic

tuberosity)▫ Facet-smooth area▫ Fovea-small pit (fovea capitus…head of the femur)

Femur

The Muscular System

•Muscles are tissues that contract to produce movement.

•Muscles are responsible for the following:▫ambulation▫control of organs and tissues▫pumping of blood▫generation of heat

Muscles

•Muscles are made up of long, slender cells called muscle fibers.

•Each muscle consists of a group of muscle fibers in a fibrous sheath.▫My/o is the combining form for muscle.▫Fibr/o and fibros/o are combining forms

for fibrous tissue.

Types of Muscle Tissue

SKELETAL MUSCLE TISSUEVoluntary = conscious thoughtStriated = stripedMuscle cell = many nuclei and mitochondria

Types of Muscle Tissue

CARDIAC MUSCLEInvoluntary = unconscious thoughtStriated = stripedIntercalated Discs

Types of Muscle Tissue

SMOOTH MUSCLEInvoluntaryNot striated

Examples: Urinary bladder, walls of the stomach, blood vessels

Structures Associatedwith Muscles

• Fascia is a sheet of fibrous connective tissue that covers, supports, and separates muscles.▫Fasci/o and fasc/i are combining forms for

fascia.▫Plural is fasiae

Structures Associatedwith Muscles

• Tendons are fibrous connective tissues that connect muscle to bone (or other structures).▫Tend/o, tendin/o, and ten/o are combining forms for

tendon.

▫Linea Albaapponeuroses that connects abdominal muscles to the abdominal wall

Nuchal Ligament•Ligament: Connects bone to bone

The nuchal ligament Origin: cervical vertebrae and the skullInsertion: dorsal spinous process of the fourth thoracic vertebra

Origin and Insertion•Muscle Origin- place where a muscle begins

attached / the part (or end) of the muscle closest to midline. (Tends to be relatively fixed)

•Muscle Insertion- place where a muscle endsis more moveable, is portion of the muscle farthest from midline

Muscles may be named according to where they originate and end.

Brachioradialis muscles are connected to the brachium (humerus) and to the radius.

Muscle Terms Kinesiology is the study of movement.

▫Kinesio/o and -kinesis mean movement.

• Antagonistic muscles work against or opposite other muscles. ▫anti- = against▫agon = struggle

Synergist muscles work with other muscles to produce movement.▫syn = together▫erg = work

Superficial muscles of the dog

•Head and Neck▫Masseter, Brachiocephalicus, Trapezius,

•Thoracic Limb (front limb)▫Deltoid, Biceps Brachii, Triceps Brachii,

Latissimus Dorsi, Pectoral•Abdominal muscles

▫External Abdominal Oblique, Intercostal•Pelvic Limb (back limb)

▫Gluteal, Biceps femoris, semitendinus, gastrocnemius

Anatomy & Physiology TM

86

MasseterBrachiocephalicus

Biceps femoris

Gastrocnemius

Semitendinous

Intercostal

Triceps brachii

Deltoid

Gluteals

Trapezius

Latissimus dorsi

External abdominal oblique

Pectorals

Naming Muscles

•Muscle movement terms:▫Abductor-muscle that moves a part away from

midline Adductor-

▫Flexor-muscle that bends a limb at its joint or decreases the joint angle. Extensor-

▫Levator-raises or elevates a part Depressor-

▫Rotator-muscle that turns a body part on its axis▫Supinator-muscle that rotates the palmer or

plantar surface upward Pronator-

Naming Muscles

•Muscle location terms:▫Pectoral-chest▫Epaxial-above the pelvic axis▫Intercostal-between ribs▫Infraspinatus-beneath the spine of the scapula▫Supraspinatus-above the spine of the scapula

▫Inferior-below or deep, Medius-middle, Superior-above

▫Externus-outer vs internus- inner▫Orbicularis-surrounding another structure

Naming Muscles

• Muscle fiber directional terms:▫ Rectus-straight/ align with the vertical axis (rectus abdominus)▫ Oblique-slanted-slant outward away from midline (external abdominal oblique muscles)▫ Transverse- crosswise- crosswise to the midline (transversus abdominus muscle)▫ Sphincter- tight band-ringlike and constrict (Urinary sphincter)

• Number of muscle division terms:▫ biceps▫ triceps▫ quadriceps

Naming Muscles

•Muscle size terms:▫Minimus▫Maximus (Vastus)▫Major ▫Minor ▫Latissimus ▫Longissimus (Gracilis)

Naming Muscles

•Muscle shape terms:▫Deltoid – delta ▫Quadratus – square/ four sided▫Rhomboideus- diamond shape▫Scalenus- unequal three sided▫Serratus – sawtoothed/notched▫Teres - cylindrical

deltoid

Latissimus dorsi

pectorals

Abdominal obliques

triceps biceps

Pathological conditions for the Musculoskeletal System•Ataxia - lack of voluntary control of muscle

movement•Atonic - lacking muscle control•Dystrophy - defective growth•Fibroma - tumor composed of fibrous

connective tissue•Hernia - protrusion of an organ or fascia

through the wall of the cavity that normally contains it

•Myopathy- abnormal condition of disease of muscle

•Tetany – muscle spasms or twitching

Ataxia-lack of voluntary control of muscle movement “wobbliness”

Tetany-muscle spasms or twitiching