CAT SKELETON

Atlas

Atlas

• First vertebrae is differentiated into the atlas; ring-shaped with wide winglike lateral projections which represent ribs and hence are perforated by an opening, the vertebrarterial canal

Neural arch

• basidorsals, the bases of which comprise the atlas

Hypocentrum

• Median ventral region of the atlas

Axis

• arge elongated neural arch having a neural spine which projects forward over the atlas and bears posteriorly a pair of post-zygapophyses

Pleurocentrum (odontoid process)

Median pointed projection of anterior end of the centrum of the axis; fits into the ring of the atlas, allowing the turning of the head; centrum of the atlas

Anterior articular process

• found on each side of the centrum of the axis

Pleurapophyses

transverse processes consisting in part of a fused-on rib

Long ribs

• reaching the ventral side; can be recognized when isolated by the smooth costal half-facets where the ribs were attached

Neural spines

• very tall in majority of thoracic vertebrae

Capitula

• half facets for capitula found at the ends of the centra

Vertebral ribs

• bony; bicipital, with the reduced tuberculum engaging the costal facet on the under side of the transverse process, and the capitulum attached between two centra to the demifacets.

Bicipital

• The tuberculum diminishes posteriorly, so that the last three ribs have only capitular heads

Neck

narrowest part of the rib between the two capitular heads

Shaft

remainder of the rib

Angle

• point of greatest curvature of the shaft

True ribs

• ribs which reach the ventral side and are independently attached to the breastbone

False ribs

• those which join the ribs preceding the true ribs or are unattached below

Floating ribs

unattached false ribs

Neural spines

prominent part of the lumbar vertebrae

Pleurapophyses

• long transverse processes directed forward; probably pleurapophyses, i.e., composed of fused diapophysis and rib.

Spine

sacrum

• composed of a variable number of vertebrae fused together for articulation with the hind limbs

Chevron bones

• of common occurrence in the tails of mammals; very small ones occur in the cat tail but are usually lost in preparing the skeleton

Amphiplatyan

both centrum ends are flat

Intervertebral cartilages

• Between the centrum ends of mammals are found in life cartilaginous disks, the intervertebral cartilages, which are homologous to the hypocentra of reptiles.

Intervetebral foramen

• between successive centra a series of openings; through which the spinal nerves pass out from the spinal cord.

Interclavicle & precoracoid

• Vanished in all placental mammals

Coracoid

Reduced to a projection on the scapula

Clavicles

• Frequently reduced or wanting; small, slender bones imbedded in muscle and as they are not articulated to any other part of the skeleton, they generally fall off in prepared skeletons

Scapulae

• large, flat, triangular bones above the anterior ribs.

Spine

• A prominent ridge on the outer surface of the scapulae

Acromion process

• A pointed projection on the ventral end if the spine; usually serving to receive one end of the clavicle.

Metacromion process

• Above the acromion, a backward projection

Glenoid fossa

• The apex of the scapula is concavely curved, forming the glenoid fossa

Coracoid process

• From the anterior side of the glenoid rim there projects medially a small beaklike coracoid process, the vestige of the coracoid bone, which embryologically forms by a separate center of ossification.

Supraspinous fossa

• the part of the external surface of the scapulae anterior to the spine

Infraspinous fossa

• the part of the scapulae posterior to the spine

Subscapular fossa

the whole internal surface of the scapulae

Anterior border

the anterior margin of the scapulae

Posterior border

the axillary border

Dorsal border

vertebral border

Sternum

consists of a longitudinal series of pieces, the sternebrae

Sternebrae Manubrium

• articulates with the first thoracic rib at its center

Xiphisternum

• Last piece of sternebrae

Xiphoid / ensiform cartilage

• Where the xiphisternum terminates

Humerus

• has a large, rounded head fitting into the glenoid fossa

Greater & lesser tuberosities

• Found at the sides of the rounded head of the humerus

Ridges/crests

• The anterior surface of the humerus below the tuberosities is slightly elevated into ridges or crests, which serve as points of muscle attachment.

capitulum

outer mass of forearm

trochlea

medial mass of humerus

Epicondyles

• situated above the trochlea and a projecting ridge

Supracondyloid foramen

Near the medial epicondyle the bone is pierced by an opening

Olecranon process

• the proximal end of the ulna forms a prominent projection, the olecranon or elbow.

Semilunar notch

• a deep semicircular concavity found distal to the elbow and articulates with the trochlea of the humerus

Coronoid process

• distal border of the notch forms this projection

Scapholunar

Articulating with the distal end of the radius

Radiale

medial navicular in the rabbit’s wrist bone

Greater multangular

First carpale

Lesser multangular

Second carpale

Hamate Metacarpals

fused fourth and fifth carpals

• consists of the usual three bones indistinguishably fused

Ilium

• the most dorsal and largest of the three components of three bones; articulates with the sacrum and terminates anteriorly and dorsally in a curved border (crest)

Ischium

• that part of the dorsal region of the girdle posterior to the acetabulum

Pubis

the anterior ventral part of the pelvic girdle

Pubic symphysis

formed by the rami meeting

Obturator foramen

found between the rami of the ischium and pubis

Greater trochanter

• lateral to the head (in rabbits- continuing to a small posterior projection to, the third trochanter)

Lesser trochanter

below the head of the femur

Condyles

the large articulating surfaces at the distal end of the femur

Epicondyles

additional elevations or roughened areas of the hindlimbs

Patella

found at the knee joint

Shank

• composed of a strout tibia and slender finulat

Tibia

fused in the rabbit with for the greater part of its length

Condyles

proximal articulating surfaces at the anterior face of the tibia

Calcaneus/fibulare

largest and most conspicuous ankle bone that projects backward as a heel

Astragalus/talus

articulates with the malleoli of the tibia and fibula

Scaphoid/navicular

found directly in front of the astragalus

Cuboid

fused fourth and fifth tarsalia found in front of the calcaneus articulating with the fourth and fifth metatarsals

third or lateral cuneiform

articulating with the third metatarsals; found medial to the cuboid

Second or intermediate cuneiform

articulating with the second metatarsal; medial to the lateral cuneiform

first or medial cuneiform in cats

articulating with the small rudimentary first metatarsal; along the medial border of the anterior part of the ankle in front of the navicular

first cuneiform in rabbits

• fused to the proximal end of the second metatarsal

Digtigrade

gait of the cat

Skull

• hard, bony case composed of separate bones, immovably jointed together in dovetail fashion along the sutures

Nose and eyes

• distinguishable from the expanded posterior cranial region enclosing the brain and including the middle and internal ears.

External nares

• At the anterior end of the facial region

Septum of the nose

• cartilaginous partition separating the nares

Orbit

At the side of the facial region, there is a large, nearly circular _________

temporal fossa

Partially separates the orbits by bony projections from the ___________________ behind it, filled in life with muscles

zygomatic arch

• The lower boundary of these fossae is formed by a projecting arch, the _______________, a very characteristic feature of the mammalian skull.

postorbital processes

• In the cat the orbit is bounded posteriorly by two ________________, one projecting dorsally from the middle of the zygomatic arch and the other descending from the roof of the skull.

Supraorbital arch

• Above the orbit is a projecting margin, the _____________, the posterior end of which forms the postorbital process

Foramen magnum

At the posterior end of the cranial portion of the skull

occipital condyle

• on each side of the foramen magnum is a projection, the ___________, which articulates with the atlas

tympanic bulla

• Lateral and slightly anterior to each occipital condyle is a conspicuous hollow expansion, the _______________, which contains the middle ear.

Tympanic cavity

cavity of the middle ear

Mastoid process

anterior process of tympanic bulla