Anatomy of Felis catus. Differences in comparison to the dog. In the cat, but not in the dog: The dorsal border of the scapula normally projects above the spinous processes of the thoracic vertebrae. The coracoid process is a well developed projection. The acromion has a hamate process and a suprahamate process. The clavicle is well developed and palpable. The humerus contains the supracondylar foramen, through which the brachial artery and median nerve pass. The supratrochlear foramen is absent. The coronoid fossa of the humerus accommodates the medial coronoid process of the ulna. It is located medial to the radial fossa. The cat has greater supintion ability of the paw. The long bones of the limbs are straighter in the cat. There are 8 mammary glands in the cat. (dogs usually average 10) The superficial pectoral m. extends beyond the elbow and inserts on the ulna. The cleidobrachialis m. also extends beyond the elbow and inserts on the ulna. The triceps brachii m has an additional short part of the medial head. The biceps brachii m terminates on the radius only. The brachialis m. terminates on the ulna only. The brachioradialis m. is very well developed. It originates on the lateral epidcondylar crest of the humerus, crosses flexor surface of elbow, and terminates on the medial surface of the distal radius. Its action is supination. It is innervated by the radial n. The extensor carpi radialis m. has two heads. The lateral digital extensor m inserts on digits 2,3,4,and 5. (in dogs, just 3,4,5.) The radial and ulnar heads of the deep digital flexor muscle are much larger in the cat than the dog. Short digital flexor mm are present. The claw is retracted by dorsal elastic ligaments between the middle and distal phalanges. In the retracted position, the distal phalanx is lateral to the middle phalanx. The same arrangement is present in the pelvic limb. The common interosseus artery is absent. The cranial and caudal interosseus aa. arise separately from the brachial a. the ulnar a. arises from the caudal inerosseous a. The radial a. is the main source of blood to the manus. The PMCAs are the largest vessels in the manus. The omobrachial v. is absent. The radial n. crosses the superficial surface of the supinator m. Specialized tactile elevations and vibrissae are present on the caudal surface of the antebrachium (carpal organ) and on the base of the tail (subcaudal organ). Pelvic bones are near parallel with little curving - radiographic "box pelvis" Femoral shaft is straight. Sacrotuberous ligament is absent. Metatarsal bones are much longer than metacarpal bones. Caudofemoralis m. (cranial crural abductor) is present. It originates on caudal vertebrae 2-4. Its muscle belly is situated between the biceps femoris m and the superficial gluteal m. It terminates via an aponeurosis into the fascia lata. A thin tendon can be traced to the lateral side of the patella. Innervation is via caudal gluteal n. It abducts the hip joint. Pectineus m. is very small and closely applied to cranial surface of adductor longus m. Sartorius m. is undivided. Soleus m. is present. It originates from the head of the fibula and its tendon contributes to the tendon of the lateral head of the gastrocnemius m. Innervation is via the tibial n. Short digital flexor mm are present as muscle bellies in the tendon of the superficial digital flexor m., distal to the tarsus. superficial circumflex iliac artery usually arises from lateral circumflex femoral artery. Medial saphenous vein is larger than lateral saphenous and is used for venipuncture (reverse in dog.) Vertebral bodies are longer and more rectangular. Nuchal ligament is absent. Cat skull has no alar canal. Round foramen opens directly onto the external surface of the skull. Tympanic bulla has prominent septum subdividing it into typanic and endotympanic parts. Zygomatic process of frontal bone longer in cat. Orbital ligament may completely ossify in older cats. Very short nasal cavity. Spenoidal sinus is present. Frontal sinus is undivided. Maxillary recess is very small. Cat has fewest teeth of any common domestic animal. Roots of P4 extend to the wall of the orbit. Laryngeal ventricles and vestibular ligament are absent. Corniculate and cuneiform processes of arytenoid cartilage are absent. divisions of thyroarytenoideus m are not distinct. Thire is a circumoral organ around the mouth that produces pheromones. Lyssa is absent or poorly developed. Dorsal surface of tongue is roughened by cornified, caudally directed filiform papillae. Foliate papillae on tongue do not contain taste buds. Parotid duct enters vestibule opposite 2nd or 3rd superior cheek tooth. pupil can be narrowed to vertical slit Third eyelid can be actively protruded by slips of the levator palpebrae superioris m. and lateral rectus m. - often seen in tranquilized or depressed cats. In adult, extracranial portion of internal carotid a. becomes a nonpatent fibrous cord. rete mirabile of maxillary a. formed near foramen ovale. This plexus extends to the apex of the periorbital region and gives rise to vessels supplying the bulb and adnexa. Caudal end of spinal cord is at the level of L7-S1. Contrast radiograph of esophagus caudal to heart shows transverse folds. Tunica muscularis of esophagus is striated muscle in cranial 2/3 and smooth in caudal 1/3. Esophageal wall is thinner in middle than cranially or caudally. Esophageal lumen narrowest cranially and caudally. Heart more caudal. Male cat lacks cremaster muscle. Cecum only short, comma shaped diverticulum. Pancreatic duct only one present. Accessory pancreatic duct present in only 20% of cats. (accessory duct largest in dog.) Large capsular veins present on external surface of kidney. Cortex of kidney is yellowish. R kidney is opposite L2-L4, L kidney opposite L3-L4 Feline kidneys more pendulous Urinary bladder has long thin neck often mistaken for urethra Bladder has abdominal location Long broad ligaments of female have less fat Ovaries are only partly enclosed by ovarian bursa. Ovarian pedicle is longer scrotum is ventral to anus, covered with dense hair, and not pendulous. testes are vertical, w/tail of epididymis located dorsally. bulbourethral glands are present. prostate gland covers only dorsal and lateral aspects of urethra (dog also covers ventral) Penis is short and directed caudoventrally. there are cornified spines on the free part of the penis in mature intact animal. penile urethra is very narrow glans penis is undivided and conical.