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UNIT 1. ANATOMY, BRANCHES AND IT APPLICATIONS
Anatomy - branch of science that deals with the form and structure (morphology) of all organisms
- the art of separating the parts of an organism in order to ascertain their position, relations, structure, and function
Divisions: I. Macroscopic or gross anatomy - study of structures of the body (tissues and organs) with the naked eye Comparative anatomy - study of structures of different animal species; focusing on the distinct anatomical differences and correlations between these differences
II. Microscopic anatomy (cytology and histology) - study of cells, and structural organization of tissues, organs and systems with the use of a microscope Ultrastructural cytology - study of ultrastructural feature of cells (very minute structural details cellular components) with the use of an electron microscope Pathologic anatomy – study of organs functionally deviating from the normal
III. Embryology - study of developmental anatomy (ontogenesis); beginning from fertilization to birth of the offspring Teratology – study of abnormal development
Methods of study:
- systemic approach – the body is regarded as consisting of systems of organs which are similar in origin and structure and are associated in the performance of certain functions a. osteology b. syndesmology c. myology d. splanchnology e. angiology and cardiology f. neurology g. esthesiology h. dermatology
- topographic anatomy – relative positions of the various parts of the body are accurately determined
- applied anatomy – anatomical facts in relation to surgery, physical diagnosis and other practical branches
History of the current medical etymology and anatomical nomenclature
1895 Basle Nomina Anatomica 1955 Nomina Anatomica – International Congress of Anatomists in Paris 1989 6 th^ ed of Nomina Anatomica – published by Churchill Livingstone
1968 Nomina Anatomica Veterinaria – published by International Committee on Veterinary Anatomical Nomenclature (appointed by the World Association of Veterinary Anatomists) 1994 4 th^ ed of Nomina anatomica veterinaria
TOPOGRAPHICAL AND DIRECTIONAL TERMS USED IN ANATOMY
Planes
- Median plane - an imaginary plane passing through the body craniocaudally. It divides the body into equal right and left halves
- Sagittal /paramedian plane - any plane parallel to the median plane
- Transverse plane - plane at right angles to the median plane (cross-section of body); dividing the body into cranial and caudal parts
- Dorsal plane - plane at right angles to both median and transverse plane. Dividing the trunk into a dorsal and ventral part
B. Areas/Location
- Cranial and anterior - mean more towards or relatively closer to the head. The term applies to the limbs proximal to the carpus and tarsus.
- Caudal and posterior - mean more towards the tail
- Rostral - means toward or close to the nose (used only when referring to structures of the head)
- Medial - means toward or close to the median plane
- Lateral - means away from the median plane
- Dorsal - means toward or beyond the vertebral column or backbone. Dorsum – the dorsal portion of the back
- Ventral - means away from the vertebral column, towards the mid-abdominal wall. It is used for parts of the body far from the vertebral column
- Deep and internal - refer to closeness to the center of gravity or center of extremity
- Superficial and external - refer to proximity to skin or surface of body or surface of an extremity
- Proximal - means close to a given part usually body, vertebral column or center of gravity. It is usually used in reference to the limbs (parts of limb near the vertebral column)
- Distal – used for parts of the limb far from the vertebral column
- Axial – situated around, in the direction of, on, or along an axis Axis - a straight line about which a body or a geometric figure rotates or may be supposed to rotate; a straight line with respect to which a body region is symmetrical; central line of the body or any of its parts
- Abaxial - situated out of or directed away from the axis
C. Movement/Direction
- Dorsad - movement towards the vertebral column
- Ventrad - movement away from the vertebral column
- Caudad - movement towards the tail
- Craniad - movement towards the head
- Palmar/Volar - flexion or caudal surface of forelimb below the elbow
- Plantar - caudal surface of hindlimb below the hock joint or ankle
- Prone - position in which the dorsal aspect or dorsum of body or extremity is uppermost Pronation - turning toward a prone position
- Supine - position in which the ventral aspect or dorsum of body
- volar (forelimb) or plantar (hindlimb) part is uppermost Supination - turning toward the supine position
- Abduction – movement away drom the median plane
- adduction – movement towards the median plane
- Line - small ridge or mark on a bone
Articular depressions in a bone
- Glenoid cavity - shallow articular depressions or concavity (e.g. of the scapula)
- Cotyloid cavity - deep articular depression (e.g. acetabulum of the hip joint)
- Notch - articular indentation
Non-articular depressions in a bone
- Fossa - large non-articular depression (e.g. infraspinous fossa of scapula)
- Fovea - small non-articular depression (e.g. fovea capitis on head of femur)
- Foramen - hole/perforation in bone (e.g. foramen magnum, nutrient foramen)
- Canal - tunnel through one or more bones (e.g. vertebral canal)
Blood vessels and nerves
- nutrient or medullary artery and vein – serves the marrow passing through the nutrient foramen and canal in long and short bones, these terminate into epiphyseal plates and anastomose with branches from periosteal vessels, in young animals, they end in capillaries
- periosteal artery and vein – supply extremities of long and compact bones
- lymph vessels – found in the periosteum as perivascular sheaths
- nerves are primarily sensory
Bones Comprising the Canine Skeleton
Axial skeleton skull and hyoid 50 vertebral column 50 ribs and sternum 34
Appendicular skeleton pectoral limb 90 pelvic limb 96
Heterotropic skeleton os penis 1
321
Vertebral column
Function: protect the spinal cord and roots of spinal nerves, support of the head, attachment of muscles related to body movements
Basic movements of the vertebral column
- flexion or dorsal arching of the spine
- extension, straightening or ventral arching of the spine
- lateral flexion
- rotation
A typical vertebrae consist of the body, vertebral arch with a right and left pedicle and lamina, and processes for muscular or articular connection.
- Body convex cranial articular surface centrally depressed caudal articular surface intervertebral fibrocartilage or disc is located in between adjacent vertebrae center of the vertebrae has a pulpy nucleus (nucleus pulposus) surrounded by a fibrous ring
- Vertebral arch or neural arch pedicle laminae – dorsal part of vertebral arch composed of a right and left lamina the vertebral arch and body forms the vertebral foramen
all foramina concur to form the vertebral canal cranial vertebral notch is shallow caudal vertebral notch is deep when the vertebrae are articulated, notches on either side of adjacent vertebrae with fibrocartilage form the right and left intervertebral foramina where the spinal nerves, arteries and veins pass
- Processes spine or spinous process – the union of the right and left lamina transverse processes projects laterally in the cervical region, the transverse foramen divides the process into dorsal and ventral parts i. dorsal part is an integral part of the transverse process e.g. the transverse process of the thoracic vertebrae ii. ventral part is homologous to a rib articular processes are present in the cranial and caudal surface at the junction of the root and lamina cranial process (prezygapophysis) faces craniodorsally or medially caudal process (postzygapophysis) faces caudoventrally or laterally
Classification of vertebra based on region:
- cervical
- thoracic
- lumbar
- sacral
- caudal or coccygeal
Vertebral formula of the dog: C 7 T 13 L 7 S 3 Cd 20 A vertebral formula consists of the first letter of the word designating each vertebral group followed by the digit designating the number of vertebrae in a specific group. All vertebrae except the sacral remain separate and articulate with contiguous vertebrae in forming movable joints. The three (3) sacral vertebrae fuse to form the sacrum ( os sacrum ).
SYNDESMOLOGY
Articulation or joint – formed by union of two or more bones or cartilage by other tissues Examples: The mandible forms a synovial joint with the temporal bone, hyoid bone is attached to temporal bone by cartilage, and sutures are immovable joints between bones of the skull.
Classification:
- fibrous joint segments are united by fibrous tissue fixed or immovable joint no joint cavity most are temporary and later ossify with a resulting synostosis a. suture – joints in the skull b. syndesmosis – uniting medium is white fibrous or elastic tissue or a mixture shafts of metacarpals attachment to each other of costal cartilages when opposed ends are untied by fibrous tissue e.g. fusion of radius and ulna in the horse, the original material undergoes ossification with age (synostosis) c. gomphosis – applied to the implantation of teeth into alveoli
- cartilaginous joint united by fibrocartilage or hyaline or a combination of both a. synchondrosis (hyaline cartilage joint) – temporary – cartilage is converted to bone before adult life example: epiphyseal plate, basilar part of occipital bone with body of basisphenoid, petrous temporal bone and stylohyoid, costochondral junction, intermandibular synchondrosis b. symphysis (fibrocartilaginous) – contiguous bones are united by fibrocartilage during some phase of their existence example: pelvic symphysis, sternebrae, joints between bodies of vertebrae
- synovial joint (diarthrodial) a joint cavity with synovial membrane in joint capsule is present a movable joint
MYOLOGY
Muscles have the property of contractility and conductivity. Instead of cells, muscles consist of fibers because of their arrangement.
Classification:
- smooth muscle – spindle-shaped cells in walls of hollow organs and blood vessels, glands, eyeball, hair follicle, produces weak rhythmic but sustained contractions, involuntary
- cardiac muscle – with cross-striations, involuntary
- skeletal muscle – multinucleated fibers that terminate by attaching to connective tissue each fiber is covered by endomysium, a bundle surrounded by perimysium and the entire muscle by epimysium fascia – connective tissue separating muscles from each other and binding them in position; depending on their location, can be superficial or deep fascia
Appearance based on arrangement of fibers
- parallel
- pennate unipennate bipennate multipennate
- fusiform
The thickest part of a muscle is the belly. An intermediate tendon produces two bellies (digastric). To produce skeletal movements, the muscle must traverse at least one joint.
- muscles in association with superficial fascia move the skin
- sphincters surround a natural body orifice
- constrictors are arranged on walls of tubes or cavities origin – attachment of muscles which remain stationary during movement, the opposite is its insertion. In the limbs, the origin is the proximal attachment while the insertion is the distal attachment. Groups of muscles combine their effort to produce a characteristic movement. These muscles are called prime movers or agonists. An antagonistic muscle opposes movements produced by agonists. The action of a muscle or group of muscles on a joint depends on their location relative to a joint. Extensors are on the side of a hinge joint where contraction will align the bones or straighten the limb. Flexors cross the surface where the smaller angle between bones are formed. Tendons are bound to the limb by annular ligaments (retinacula). If there is much movement or change in direction over a joint, the tendon is surrounded by a synovial sheath. If limited movement but pressure exists against a part of the long bone, a bursa occurs between tendons and bone. Aponeuroses are thick sheets of connective tissue that serves as origin or insertion to muscles.
Tendons - join skeletal muscle to bone function: transmit force in one direction, and act as shock-absorbers may pass through groove or sheath Golgi tendon organs: special nerve endings: measure force (stretch?) outer sheaths: white; random collagen; many fibroblasts - epitenon, epiligament insertions: blend with periosteum; some penetrate bone; folding at myotendinous junction
SPLANCHNOLOGY
RESPIRATORY SYSTEM
In general, the system is made up of two portions: the conducting and the respiratory portions. The first portion is involved in the taking and releasing of air and the respiratory portion is involved in exchange of gases, CO 2 to O 2.
Functions of the Conducting Portion :
- allows passage of air
- modify and regulate air – humidify, removes foreign objects etc.
- serves as site of olfactory receptors (smell; ethmoturbinates)
- facilitate heat and water exchange or thermoconduction
- make phonation/sound production possible.
Parts of the conducting portion:
- nose
- pharynx – naso and oropharynx
- larynx and laryngopharynx
- trachea
- bronchi and bronchioles
CIRCULATORY SYSTEM
The whole extent of the circulatory system is composed of tubular organs.
- Heart and related structures
- Pulmonary Circulation
- Coronary Circulation
- Portal Circulation
- Systemic Circulation a. Systemic arteries b. Systemic veins
DIGESTIVE SYSTEM
The digestive system consist of a musculomembranous tube extending from mouth to anus. It functions for ingestion, rendering, digestion and absorption of food, and elimination of solid wastes.
Layers of a tubular organ
- Tunica mucosa
- Tunica submucosa
- Tunica muscularis
- Tunica adventitia or serosa
Alimentary canal
- mouth & oral cavity including the lips, teeth and tongue
- pharynx
- esophagus
- stomach
- small intestines
- large intestines including cecum, rectum and anus
Accessory glands
- salivary glands – mandibular, parotid, sublingual and zygomatic (only in the dog and cat)
- liver including the gall bladder
- pancreas
URINARY SYSTEM
The ultimate function of the urinary system is the filtration of blood and elimination of harmful wastes. It is generally composed of a filtration organ, organ for storage of urine and means to transport and eliminate urine from the body.
UNIT 2. THORACIC LIMB
Bones
Bones of the thoracic limb:
- The pectoral girdle consists of the left and right clavicle and scapula.
- The arm or brachium consists of the humerus,
- the forearm or antebrachium represented by the radius and ulna,
- the forepaw or manus includes the wrist or carpus, with its digits consisting of the metacarpals, phalanges and dorsal and palmar sesamoid bones.
- Shoulder girdle – clavicle and scapula Clavicle – located in the tendinous intersection of the brachiocephalicus muscle, its medial end attached to the sternal fascia by a ligamentous band not articulated with the skeleton The clavicle of the dog does not usually appear on radiographs. There is no articulation of the shoulder with the axial skeleton.
- brachium – humerus
- antebrachium – radius and ulna ulna is well-developed a small amount of movement is possible between these two bones
- manus carpus – 7 (carpal) bones
- proximal row from the radial to the ulnar side (inward to outward): radial, intermediate, ulnar and accessory
- distal row – numerical designation in the same direction as the proximal row: 1st, 2nd, 3rd^ and 4 th metacarpus – 5 long bones, one for each digit
- from radial to ulnar – I, II, III, IV, V
- I is smaller than the rest digits – 5 bones, homologous to fingers of man
- designated numerically from radial to ulnar side in correspondence with the metacarpus
- each digit has 3 phalanges
- 1 st^ phalanx articulates with corresponding metacarpal bone proximally and the 2nd^ phalanx distally
- 3 rd^ phalanx is enclosed in the claw Sesamoid bones are developed along the course of the tendon or in joint capsules Small sesamoid bones are situated on the extensor side of metacarpophalangeal joint and often at the proximal interphalangeal joint.
A. Joints in the Forelimb Synsarcosis - false jt. between scapula and bony thorax (since 2 structures are held in place by muscles and ligaments
- Shoulder jt - scapula + humerus (head)
- Elbow jt - humerus (condyles) + proximal ends of radius and ulna;
- Carpus (knee jt – in horses) - distal end of radius + proximal row of carpal bones; proximal row + distal row of carpal bones; distal row of carpal bones + proximal metacarpal bones
- Metacarpophalangeal jt - distal metacarpus + proximal ends of phalages
- Proximal interphalangeal jt – between 1st + 2nd phalanges
- Distal interphalangeal jt - between 2nd + 3rd phalanges & distal sesamoid bone
EXTRINSIC MUSCLES OF THE THORACIC LIMBS
Pectoral Muscles: A. Superficial pectoral Two parts: a. descending pectorals b. transverse pectorals Origin: first two sternebrae Insertion: whole crest of the greater tubercle of the humerus Action: to adduct the limb Innervation: cranial pectoral nerves
B. Deep Pectoral (ascending pectoral) Origin: ventral part of the sternum
Insertion: lesser tubercle of the humerus, aponeurosis of the greater tubercle and its crest and medial brachial fascia Action: pull trunk cranially when the limb is advanced, extend the shoulder and to draw the limb caudally when it is not supporting weight Innervation: caudal pectoral nerves
Brachiocephalicus Divided into 2 parts: a. distal to the clavicular intersection cleidobrachialis b. muscle that extends from the clavicular tendon to the dorsum of the neck cleidocervicalis cleidomastoideus Origin: clavicular intersection Action: to advance the limb; extend the shoulder and the head and neck from side to side Innervation: accessory nerve and ventral branches of the cervical nerves
Sternocephalicus Divided into two parts: a. sternomastoideus b. sternooccipitalis Origin: manubrium Insertion: mastoid part of the temporal bone and nuchal crest of the occipital bone Action: to draw the neck to the side Innervation: accessory nerve and ventral branches of the cervical nerves
Sternohyoideus Origin: manubrium Insertion: basihyoid Action: to pull the tongue and larynx caudally Innervation: ventral branches of the cervical nerves
Sternothyroideus Origin: first coastal cartilage Insertion: thyroid cartilage Action: to draw the tongue and larynx caudally Innervation: ventral branches of the cervical nerves
Omotransversarius Action: to advance the limb or flex the neck laterally Innervation: accessory nerve
Trapezius Divided into two parts: a. thoracic b. cervical Origin: median raphe of the neck and supraspinous ligament Insertion: spine of the scapula Action: to elevate and abduct the forelimb Innervation: accessory nerve
Rhomboideus Divided into three parts: a. thoracic b. capital c. cervical Origin: nuchal crest of the occipital bone; median fibrous raphe of the neck and the spinous process of the first seven thoracic vertebrae Insertion: dorsal border and adjacent surface of the scapula Action: to elevate the forelimb and draw the scapula against the trunk Innervation: ventral branches of the cervical and thoracic nerves
Latissimus dorsi Origin: thoracolumbar fascia Insertion: teres major tuberosity of the humerus and teres major tendon Action: to draw the limb caudally and flex the shoulder
Triceps brachii Consists of four heads: a. long head Origin: caudal border of the scapula Insertion: the olecranon Action: to extend the elbow and flex the shoulder Innervation: radial nerve b. lateral head Origin: tricipital line of the humerus Insertion: the olecranon Action: to extend the elbow Innervation: radial nerve c. Accessory head Origin: neck of the humerus Insertion: the olecranon Action: to extend the elbow Innervation: radial nerve
d. Medial head Origin: crest of the lesser tubercle Insertion: the olecranon Action: to extend the elbow Innervation: radial nerve
Anconeus Origin: lateral epicondylar crest and the lateral and medial epicondyles of the humerus Insertion: lateral surface of the proximal end of the ulna Action: to extend the elbow Innervation: radial nerve
Cranial Muscle of the Arm Biceps brachii Origin: the supraglenoid tubercle Insertion: the ulnar and radial tuberosity Action: to flex the elbow and extend the shoulder Innervation: musculocutaneous nerve
Brachialis Origin: proximal third of the lateral surface of the humerus Insertion: the ulnar and radial tuberosity Action: to flex the elbow Innervation: musculocutaneous nerve
Cranial and Lateral Muscles of the Forearm Extensor carpi radialis Origin: lateral epicondylar crest Insertion: small tuberosity on the proximal ends and dorsal surfaces of metacarpals II and III Action: to extend the carpus Innervation: radial nerve
Common digital extensor Origin: lateral epicondyle of the humerus Insertion: extensor process of the distal phalanges of digits II, III, IV and V Action: to extend the joints of the four principal digits Innervation: radial nerve Lateral digital extensor Origin: lateral epicondyle of the humerus Insertion: proximal ends of all phalanges of digits III, IV and V, but mainly the extensor processes of the distal phalanges of these digits Action: to extend the digits III, IV and V Innervation: radial nerve
Ulnaris lateralis Origin: lateral epicondyle of the hunerus Insertion: lateral aspect of the proximal end of metacarpal V and the accessory carpal bone Action: to abduct and flex the carpus Innervation: radial nerve
Supinator Origin: lateral epicondyle of the humerus Insertion: cranial surface of the proximal fourth of the radius Action: supination and flex the elbow Innervation: radial nerve Pronator teres Origin: medial epicondyle of the humerus Insertion: medial border of the radius between the proximal and middle thirds Action: pronation and flex the elbow Innervation: median nerve
Abductor pollicis longus Origin: lateral border and cranial surface of the body of the ulna; the interosseous membrane Insertion: the proximal end of metacarpal I Action: to abduct the digit or pollex Innervation: radial nerve
Cranial and Medial Muscles of the Forearm Flexor carpi radialis Origin: the medial epicondyle of the humerus and the medial border of the radius Insertion: the palmar side of the proximal ends of the metacarpals II and III Action: to flex the carpus Innervation: median nerve
Superficial digital flexor Origin: the medial epicondyle of the humerus Insertion: palmar surface of the base (proximal end) of the middle phalanges of digits II, III, IV and V Action: to flex digits II, III, IV and V Innervation: median nerve
Flexor carpi ulnaris Two heads: a. ulnar b. humeral Origin: ulnar head- the caudal border and medial surface of the olecranon; humeral head- medial epicondyle of the humerus Insertion: accessory carpal bone Action: to flex the carpus Innervation: ulnar nerve
Deep digital flexor Three heads: a. humeral b. radial c. ulnar Origin: humeral head- medial epicondyle of the humerus; ulnar head- proximal three-fourths of the caudal border of the ulna; radial head- medial third of the medial border of the radius Insertion: the palmar surface of the base (proximal end) of the distal phalanx of each digit Action: to flex the digits Innervation: median and ulnar nerves
Pronator quadratus Attachments: apposed surfaces of the radius and ulna Action: to pronate the paw Innervation: median plane
Muscles of the Forepaw Interossei
Vessels and Nerves of the Thoracic Limb Primary Vessels of the Thoracic Limb Subclavian artery Vertebral Costocervical Internal thoracic Superficial cervical
Table 1. Vessels and nerves of the Thoracic Limb AREA Arterial supply Nerve supply Lateral muscles of the Scapula and Shoulder Stabilizers, flexors and extensors of shoulder: Supraspinatus, infraspinatus
Superficial cervical Suprascapular
Caudal Muscles of Scapula and Shoulder Flexors of shoulder: Deltoideus, teres major, teres minor
Subscapular Axillary
Cranial Muscles of Arm Flexors of elbow, extensor of shoulder: Biceps brachii (Brachialis)
Superficial cervical, Axillary, Brachial
Musculocutaneous
Caudal Muscles of the Arm Extensor of Elbow: Triceps brachii
Axillary, Brachial Radial
Cranial Muscles of Forearm Carpal extensors Digital extensors
Brachial: cranial interosseous
Radial
Caudal Muscles of the Forearm Carpal flexors Digital flexors
Brachial: common interosseous, deep antebrachial
Median and ulnar
Dorsal Surface of Paw Superficial brachial, Dorsal carpal rete
Radial
Palmar Surface of Paw Median, Caudal interosseous
Median and ulnar
UNIT 3. PELVIC LIMB
Bones of the pelvic limb:
- pelvic girdle – os coxae
- thigh - femur
- leg – tibia and fibula
- pes – tarsus (tarsal bones), metatarsal bones and phalanges
- Pelvic girdle os coxae (hip bone)
- largest of the flat bones
- formed by three bones: ilium, ischium and pubis
- the bodies of the 3 parts meet to form the acetabulum
- the acetabulum articulates with the head of the femur ilium
- ilium – body forms the acetabulum, continuous with pelvic surfaces of the ischium and pubis
- wing – expanded portion presenting a crest and 2 spines gluteal or external surface is smooth, deeply concave bounded by the crest and dorsal and ventral spines pelvic or internal surface – bounded by the crest, arcuate line, dorsal and ventral spine iliac tuberosity – dorsal part for attachment of the sacroiliac ligament crest of the ilium – convex, connects the coxal and sacral tubers separated by a notch into cranial and caudal dorsal iliac spines ischium
- forms the caudal part of the hip bone
- forms the acetabulum, obturator foramen and pelvic symphysis
- tuberosity of ischium serves as area from which muscles arise
pubis
- caudal border bounds the cranial part of obturator foramen
- external surface is rough for origin of muscles e.g. gracilis
- internal surface is smooth, gives origin to internal obturator muscle
- cranial border for attachment of prepubic tendon
pelvic symphysis – joins the left and right os coxae pelvic girdle articulates with the sacrum dorsally bony pelvis is formed by the os coxae, sacrum and first few caudal vertebrae
- floor is formed by pubic and ischial bones
- lateral walls formed by the ilia and acetabular part of ischia sacrotuberal ligament and semimembranosus mm. fill the space between the sacral tuberosity and ischiatic tuber cranial pelvic inlet is bounded by the sacrum dorsally, arcuate or iliopectineal lines laterally and the pectin ossis pubis ventrally acetabulum – cup-shaped cavity which lodges the head of the femur
- acetabular fossa is its non-articular depression
- medial part of the rim is cut into by the acetabular notch knowledge of the normal anatomy of the hip joint is important for proper interpretation of radiographic anatomy because of the prevalence of hip dysplasia
- thigh femur – articulates with the acetabulum proximally and the patella and tibia distally patella – articulates with the trochlea of the distal end of the femur
- a large sesamoid bone intercalated in the tendon of the quadriceps femoris
- leg tibia – supports weight and articulates distally with the talus (tibial tarsal) fibula – located on the lateral border of the tibia separated by interosseus space
- slender than the tibia
- does not articulate with the femur
- pes tarsus
- proximal row: talus (tibial) and calcaneus (fibular) – calcaneal tuber acts as lever for the muscles that extend the hock joint
- distal row: 1st, 2nd, 3rd, 4th^ and central tarsal bone
superficial gluteal Origin: lateral border of the sacrum Insertion: third trochanter Action: extend the hip and abduct the limb Innervation: caudal gluteal nerve
middle gluteal Origin: ileal crest and gluteal surface of ilium Insertion: the greater trochanter Action: to extend and abduct the hip Innervation: Cranial gluteal nerve
deep gluteal Origin: body of lium Insertion: cranial aspect of the greater trochanter Action: to extend and abduct the hip Innervation: cranial gluteal nerve
Caudal Hip muscles
Internal obturator Origin: pelvic symphysis Insertion: trochanteric fossa of the femur Action: to rotate the pelvic limb laterally Innervation: sciatic nerve
gemelli Origin: lateral surface of the ischium Insertion: the trochanteric fossa Action: to rotate the pelvic limb laterally Innervation: sciatic nerve
quadratus femoris Origin: caudo-ventral part of the ischium Insertion: distal to the trochanteric fossa Action: to rotate the pelvic limb laterally Innervation: sciatic nerve
external obturator Origin: ventral surface of pubis and ischium Insertion: trochanteric fossa Action: to rotate the pelvic limb laterally Innervation: obturator nerve
Cranial muscles of the Thigh
quadriceps femoris Has four heads: rectus femoris vastus lateralis vastus medialis vastus intermedius Origin: rectus femoris – ilium; vasti muscles – proximal femur Insertion: tibial tuberosity Action: to extend the stifle and flex the hip (rectus femoris) Innervation: femoral nerve
iliopsoas Composed of two muscles: psoas major iliacus Origin: psoas major – lumbar vertebrae; iliacus – cranioventral ilium Insertion: lesser trochanter Action: to flex the hip Innervation: psoas - ventral branches of lumbar nerves: iliacus – femoral nerve
Craniolateral Muscles of the Crus
cranial tibial Origin: extensor groove of the tibia Insertion: the proximal plantar surface of metatarsals I and II Action: to flex the tarsus and rotate the paw laterally Innervation: peroneal nerve
long digital extensor Origin: extensor fossa of the femur Insertion: distal phalanges of digit II, III, IV and V Action: to extend the digits and flex the tarsus Innervation: peroneal nerve
peroneus longus Origin: lateral condyle of the tibia; proximal end of fibula and lateral epicondyle of femur Insertion: fourth tarsal bone Action: flex the tarsus and rotate the paw medially Innervation: peroneal nerve
Caudal Muscles of the Crus
gastrocnemius – has two head, lateral and medial heads Origin: medial and lateral supracondylar tuberosities of the femur Insertion: tuber calcanei Action: extend the tarsus and flex the stifle Innervation: tibial nerve
superficial digital flexor Origin: lateral supracondylar tuberosity of the femur Insertion: tuber calcanei and middle phalanges of digits II, III, IV and V Action: to flex the digits and stifle; extend the tarsus Innervation: tibial nerve
deep digital flexor Composed of two muscles lateral digital flexor medial digital flexor Origin: proximal tibia and fibula Insertion: plantar surface of the base of each of the distal phalanges Action: to flex the digits and extend the tarsus Innervation: tibial nerve
popliteus Origin: the lateral condyle of the femur Insertion: the proximal third of caudal tibia Action: to flex the stifle and rotate the leg medially Innervation: tibial nerve
