THE SKELETAL THE SKELETAL SYSTEMSYSTEM

CH 6CH 6

PART 2 – THE AXIAL PART 2 – THE AXIAL SKELETONSKELETON

AXIAL SKELETONAXIAL SKELETON

SKULLSKULL HYOID BONEHYOID BONE VERTEBRAEVERTEBRAE RIBSRIBS STERNUMSTERNUM

SKULLSKULL

2 major segments: 2 major segments: – Cranium & Facial bonesCranium & Facial bones

PURPOSEPURPOSE: protects the brain and : protects the brain and the sensory organsthe sensory organs

The ONLY mobile bone is the The ONLY mobile bone is the MANDIBLE (lower jaw)MANDIBLE (lower jaw)

The location that the skull bones The location that the skull bones unite is at the unite is at the SUTURESSUTURES or or seams seams

sutures

*SINUSES are located within the dense portion of the skull and are air- filled cavities

* They lessen bone weight, provide resonating chambers for vocalization, moisten/warm air, and are a site of mucous secretion

* Sinuses are usually named for the skull bone that contains the sinus

SKULLSKULL The nostrils open into 2 major air passages The nostrils open into 2 major air passages

that end in the throat. The nasal passages that end in the throat. The nasal passages are filled with very are filled with very fine scrolls of bonefine scrolls of bone called called TURBINATESTURBINATES. The turbinates are . The turbinates are covered in pink tissue (mucosa)covered in pink tissue (mucosa) similar similar to the lining of the mouth. to the lining of the mouth. Air is warmed, Air is warmed, moistened, and filtered as it passes moistened, and filtered as it passes through the turbinates in the nose on through the turbinates in the nose on the way to the lungs.the way to the lungs.   

turbinates

SKULLSKULL CRANIAL BONESCRANIAL BONES

– FRONTAL BONES (#6) – FRONTAL BONES (#6) – form the form the forehead, the orbitsforehead, the orbits, and the front , and the front portion of the cranial floor.portion of the cranial floor. HornsHorns are an extension of the frontal bone are an extension of the frontal bone

– PARIETAL BONES (#7) – form the PARIETAL BONES (#7) – form the roof roof and upper part of each side of the and upper part of each side of the skullskull

– OCCIPITAL BONE (#8) – forms the OCCIPITAL BONE (#8) – forms the back of back of the skullthe skull

SKULLSKULL

– FORAMEN MAGNUM– FORAMEN MAGNUM– openingopening at the at the base of the occipital bone that base of the occipital bone that allows allows the spinal cord to pass from the the spinal cord to pass from the skull to the spineskull to the spine

– TEMPORAL BONES (#9) – form part of TEMPORAL BONES (#9) – form part of the the cranial floorcranial floor and the lower part of and the lower part of the the sidessides. Contains middle and inner . Contains middle and inner ear structuresear structures

SKULLSKULL

FACIAL BONESFACIAL BONES– MAXILLA (#3) – bones that form the MAXILLA (#3) – bones that form the

upper jaw, nose, orbits, and roof of upper jaw, nose, orbits, and roof of the mouththe mouth

– MANDIBLE – forms the MANDIBLE – forms the lower jaw. Only lower jaw. Only movable bone in the skullmovable bone in the skull

maxilla

mandible

SKULLSKULL

– HYOID APPARATUSHYOID APPARATUS – U shaped – U shaped structure made up of both structure made up of both bone and bone and cartilagecartilage. . Located above the larynx, Located above the larynx, below the mandiblebelow the mandible, and is suspended , and is suspended from the temporal bones via ligaments. from the temporal bones via ligaments. Suspends the tongue, larynx, and Suspends the tongue, larynx, and floor of the mouthfloor of the mouth

VERTEBRAL COLUMNVERTEBRAL COLUMN

BACKBONEBACKBONE PURPOSE: PURPOSE: protects the spinal protects the spinal

cord, supports the skull and cord, supports the skull and thorax, stiffens the trunk, thorax, stiffens the trunk, anchors the pelvis, provides anchors the pelvis, provides muscle attachmentmuscle attachment

There are 5 types of vertebrae: There are 5 types of vertebrae: cervical (C), thoracic (T), lumbar cervical (C), thoracic (T), lumbar (L), sacral (S), coccygeal (Cy)(L), sacral (S), coccygeal (Cy)

Each vertebrae has a body Each vertebrae has a body and an arch. and an arch. – BodyBody – bears the weight – bears the weight– ArchArch – forms the canal that – forms the canal that

houses the spinal cordhouses the spinal cord

• Intervertebral discsIntervertebral discs are are between the bodiesbetween the bodies

-Made of -Made of cartilage and cartilage and

serve as serve as shock shock absorbersabsorbers

• Processes extend out Processes extend out from dorsal and lateral from dorsal and lateral vertebral surfacesvertebral surfaces

FORMULASFORMULAS

– DOG/CAT: C(7), T(13), DOG/CAT: C(7), T(13), L(7), S(3), Cy(6-23)L(7), S(3), Cy(6-23)

– HORSE: C(7), T(18), HORSE: C(7), T(18), L(7), S(5), Cy(15-21)L(7), S(5), Cy(15-21)

– COW: C(7), T(13), COW: C(7), T(13), L(6), S(5), Cy(18-21)L(6), S(5), Cy(18-21)

– PIG: C(7), T(14-15), PIG: C(7), T(14-15), L(6-7), S(4), Cy(20-23)L(6-7), S(4), Cy(20-23)

– SHEEP: C(7), T(13), SHEEP: C(7), T(13), L(6-7), S(4), Cy(16-18)L(6-7), S(4), Cy(16-18)

CERVICAL CERVICAL VERTEBRAEVERTEBRAE

– 11stst vertebrae: vertebrae: ATLAS:ATLAS: supports the skullsupports the skull

– 22ndnd vertebrae: vertebrae: AXIS:AXIS:

what the atlas rotates onwhat the atlas rotates on

THORACIC THORACIC VERTEBRAEVERTEBRAE

Attach to ribsAttach to ribs

THORACIC CAGETHORACIC CAGE

Composed of the Composed of the thoracic thoracic vertebrae, ribs, costal vertebrae, ribs, costal cartilages, and sternumcartilages, and sternum

Thoracic cage Thoracic cage protects the vital protects the vital organs of the chestorgans of the chest and allows and allows the the lungs to expand and lungs to expand and contractcontract during respiration during respiration

RIBSRIBS

RIBSRIBS– PURPOSEPURPOSE: form the thoracic wall and : form the thoracic wall and

protect the heart and lungsprotect the heart and lungs

– Flat, curvedFlat, curved– Each rib has Each rib has bony and bony and

cartilagenous componentscartilagenous components The cartilagenous component is located The cartilagenous component is located

ventrallyventrally They unite at the They unite at the costochondral costochondral

junctionjunction

RIBSRIBS

– AllAll attach to the thoracic vertebrae attach to the thoracic vertebrae dorsally (the dorsally (the number of thoracic number of thoracic vertebrae = the number of ribsvertebrae = the number of ribs))

– Differ in the attachment to the Differ in the attachment to the sternumsternum 11stst 7-9 join directly with the sternum 7-9 join directly with the sternum

“TRUE RIBS”“TRUE RIBS” The caudal ribs unite with the The caudal ribs unite with the

cartilagenous portion of the true ribs. cartilagenous portion of the true ribs. They are called They are called “FALSE RIBS”“FALSE RIBS”

The most caudal ribs due not unite with The most caudal ribs due not unite with anything ventrally and appear to be anything ventrally and appear to be “floating”, so they are called “floating”, so they are called “FLOATING “FLOATING RIBS”RIBS”

RIBSRIBS

STERNUMSTERNUM

BREASTBONEBREASTBONE Located on ventral midline of chestLocated on ventral midline of chest Flat bones called Flat bones called STERNEBRAESTERNEBRAE

that connect to each other via that connect to each other via cartilagecartilage

Most cranial aspect is the Most cranial aspect is the manubriummanubrium

Most caudal aspect is the Most caudal aspect is the xiphoid xiphoid processprocess

LUMBAR VERTEBRAELUMBAR VERTEBRAE

Support the abdomenSupport the abdomen

SACRAL VERTEBRAESACRAL VERTEBRAE

One bone that results from the fusion One bone that results from the fusion of 3-5 vertebraeof 3-5 vertebrae

Attaches to pelvisAttaches to pelvis

COCCYGEAL COCCYGEAL VERTEBRAEVERTEBRAE

– Also called caudal or tail vertebraeAlso called caudal or tail vertebrae

– Can be docked- spinal cord ends Can be docked- spinal cord ends near the lumbosacral junctionnear the lumbosacral junction