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Flashcards in Rear limb Deck (45):

Species differences in the bony pelvis.

Dorsal views of the ossa coxae of the dog, ox, pig and horse for comparison.

Pelvic inlet - ox, pig, and horse inlet is larger than the outlet. The canal is shaped like a truncated cone.

Roof - In the pig the caudal sacral segment does not fuse for several years and can be displaced dorsally at birth.

Lateral wall - The ischial tuber is small in the horse and pig, but large and dorsally directed in the ox (narrowing the birth canal). The porcine ossification centre of the ischial tuber fuses late - this leads to a risk of fracture because of the strong pull of the hamstring muscles. The ilial wings diverge cranially in the horse to give a 'triangular' birth canal. The ilia are parallel in the pig and ox giving a rounded canal. The angle of the ilial wings to the horzontal is more acute in females so that the inlet is more oblique. The ilial wings are almost horizontal in the pig.

Floor - Level in the horse. Slopes backwards in the pig. Hollowed in the ox. A medial symphyseal swelling is present in the horse and ox - this is obliterated in older females.


The majority of landmarks are present in all species but their sizes and positions vary. What are the major landmarks of the pelvis?

ISCHIAL TUBER - Prominent in the ox. Palpable in the pig. Not palpable in the horse.

SACROSCIATIC NOTCH - Palpable in the ox (softens at birth). Barely palpable in the pig. Not palpable in the horse.

ISCHIORECTAL FOSSA - This is a pyramidal fat-filled space. Prominent in the ox. Hidden in the pig and the horse. In the pig and the horse the semitendinosus and semimembranosus muscles arise more caudally from coccygeal vertebrae, caudal sacrosciatic ligament and ischial tuber, instead of from the ischial tuber alone (as in the ox). This obscures the caudal bony landmarks.


Bony landmarks in the horse and cow are obscured by which two muscles?

Figure 8 - Left lateral views of the horse (left) and cow (right) showing positions of semimembranosus and semitendonosus. Notice that they obscure the palpable bony landmarks in the horse.


What are the The key anatomical differences between male and female pelvic girdles?

There are differences in size and, to a lesser extent, shape of the bones of the pelvic girdle between males and females of the same species:

The female pelvis is broader. This aids the passage of the foetus during parturition.

Female bones, including the female head, are generally more slender than their male counterparts.

The following points are not essential facts, but knowledge of them will assist you in identifying bony specimens:

The greater sciatic notch is closer to being a right angle in the female. It is noticeably less acute in the male.

The female ischiatic spine lies in the plane of the body of the ischium. The male counterpart is inverted towards the pelvic cavity.

The female obturator foramen is triangular, the male obturator is oval in outline.

The distance from the pubic tubercle to the acetabular margin is greater than the diameter of the acetabulum in the female, but not in the male.


What is the comparative anatomy of the pelvic canal? 

The PELVIC CANAL, also called the birth canal, has an inlet (cranially) and an outlet (caudally), the relative diameters of which vary with species and sex. It is defined as the region between the pelvic inlet and outlet. It is formed at its cranial end by the wings of the ilium, dorsally by the sacrum, and ventrally by the pelvic symphysis. More caudally, the ischial tuber forms part of the floor and wall of the canal. The internal dimensions are reduced by soft tissues and tilting of the os coxae.



Name the boarders of the birth canal?

Vertical - from the cranial pelvic symphysis vertically upwards.

Oblique - from sacroiliac joint to iliopectineal eminence.

Transverse - greatest transverse measurement.

Conjugate - from sacral promontory to the cranial pelvic sympysis.

(Figure 11 - Cranial and left lateral views of the pelvis of a mare showing the obstetrical diameters.)

The pelvic dimensions are less important in polytoccous animals than in animals which have a single offspring. However, pelvic dimensions are incompatible with the size of the foetal head in dyschondroplastic dogs eg. chihuahua, bulldog.


What are the The anatomical changes that take place in the pelvic girdle during parturition?

Surprisingly, very few changes actually occur in the pelvic region during parturition. The process is facilitated by:

Rotation of the pelvis at the sacro-iliac joints.

Loosening of connective tissue (initiated by the hormone relaxin - secreted from the corpus luteum).

Relaxation of the pelvic symphysis at parturition probably does not occur except in the guinea pig and small rodents.

After several pregnancies, a permanent change in the shape of the pelvis may occur.


What forms the 

bony pelvic girdle of the dog?

The bony pelvis is formed by the pelvic girdle - os coxae, sacrum and first few coccygeal vertebrae.

The os coxae is made up of TWO symmetrical halves which meet at the pelvic symphysis. Each os coxarum (hip bone) is made up of THREE bones which arise from separate ossification centres. In the young animal the ossification sites are divided by radiolucent lines of cartillage. In the adult the three bones fuse and it is impossible to identify the ILIUM, ISCHIUM, and PUBIS as separate bones. The ilium forms the craniodorsal part of the hip bone. The pubis lies medially and forms the cranial part of the pelvic floor. The ischium is the most caudal part of the bone and forms the rest of the pelvic floor.



What 3 bones make up the acetabulum?



ILIUM - This consists of a cranial wing and a caudal shaft/body. In the dog and cat the wing is oblong in shape and lies in a sagittal direction. Dorsally the wing is thickened to form the cranial and caudal dorsal iliac spines and ventrally the cranial and caudal iliac spines. The dorsal border of the wing is cut away near the shaft to form the GREATER SCIATIC NOTCH, over which the sciatic nerve runs on its way to the hindlimb. The shaft is thick and its ventral border is marked by the ARCUATE line. This line is the boundary between the abdomen and the pelvis.

PUBIS - This is an 'L' shaped bone consisting of a transverse or acetabular part and a sagittal or symphysial part The two parts form approximately half of the circumference of the obturator foramen. The lateral end of the transverse part contributes to the acetabulum and is called the body.

ISCHIUM - This is a horizontal plate of bone extending cranially by symphysial and acetabular branches which complete the obturator foramen. The caudolateral part of the plate forms the ischial tuber. The part of the acetabular branch near the acetabulum is called the body. A crest, the ischial spine, lies over the body and the acetabular branch. Between the spine and the ischial tuber the bone is indented to form the LESSER SCIATIC NOTCH.

All three bones (and the acetabular bone) contribute to the acetabulum.



What are the Joints and ligaments of the pelvic girdle?

The PELVIC SYMPHYSIS join the pubis and ischium of the two hip bones. It is a secondary cartilaginous joint which ossifies with age. Ossification begins at the pubis and moves caudally.

The SACRO-ILIAC JOINTS combine a synovial joint with an adjacent area of fibrous union. This is thought to allow a firm joint with a degree of shock absorption.

The SACROTUBEROUS LIGAMENT in the dog is a stout cord which is attached to the caudal angle of the sacrum and runs to the lateral part of the ischial spine. The ligament is absent in the cat.


A ventrodorsal radiograph of a dog's pelvis


A lateral radiograph of a dog's pelvis.


Dog body references


Name the hip muscles


Pes image


Comparitive tarsus


Name dog pelvis bones


The ________ ______ in the dog is a stout cord which is attached to the caudal angle of the sacrum and runs to the lateral part of the ischial spine. The ligament is absent in the cat.



The majority of landmarks are present in all species but their sizes and positions vary.


What inserts on the pecten pubis?

rectus abdominis and pre pubic tendon


What are the boundaries of the pelvic inlet?

Dorsal border – sacral promontory
Lateral borders – arcuate lines
Ventral border – pecten pubis


Which part of the pelvic bone is palpable?

The tuber sacrale.


(sacraltuberous lig)


What are the two sacroiliac joint articulation types?

The auricular surfaces on the wings of the sacrum and ilium are covered by hyaline cartilage 

Dorsal to the auricular surface, fibrocartilage unites the wings of the sacrum and ilium


What comprises the pelvic symphysis in quadrapeds?

The ischial symphysis and pubic symphysis

The ischium is caudal and forms most of the pelvic floor. The ischial tuberosity is formed by the caudolateral corner of the horizontal plate of the ischium. The pelvic symphysis comprises both the pubis and the ischium .

The Acetabulum provides the socket to the joint of the hip, and is composed of all three bones of the pelvis.


Hip Bones

Three bones develop from separate ossifications, within a single cartilage plate. What are the bones?

1. Ilium

The ilium is craniodorsal and extends obliquely forward from the hip to articulate with the sacrum. The cranial wing varies between species. Dorsally, it forms the sacral tuber, which is more prominent in larger animals than in dogs and cats. Ventrally, it forms thetuber coxae, or the point of the hip. The margin of the wing is known as the iliac crest and the body is deeply excavated for attachment of the gluteus medius. The greater sciatic notch on dorsal border of the wing, is cut away at its junction with the shaft, to allow the sciatic nerve passage en route to the hind limb.

2. Pubis

The pubis extends medially from the joint to form the cranial pelvic floor. It is L-shaped to give two branches; cranial (acetabular) and caudal (symphysial).

3. Ischium

The ischium is caudal and forms most of the pelvic floor. The ischial tuberosity is formed by the caudolateral corner of the horizontal plate of the ischium. The pelvic symphysis comprises both the pubis and the ischium .

The Acetabulum provides the socket to the joint of the hip, and is composed of all three bones of the pelvis.


Pelvic Joints and Ligaments what are they?

Pelvic Symphysis: secondary cartilaginous joint that ossifies with age and may expand in parturition.

Sacroiliac joints: synovial joints combined with fibrous joints. They transmit the weight of the trunk to the hindlimbs.

Sacrotuberous ligament: varies tremendously between species, the caudal edge is palpable.

Species differences[edit]

Larger species have a more vertical ilium, bringing the sacroiliac joint (and with it the weight of the trunk) closer to the hip. Smaller species have an oblique ilium. The dog has a stout cord extending between the sacrum and lateral ischial tuberosity, this is not present in the cat. In ungulates, the sacrosciatic ligament expands to a broad sheet.


Explain the Pelvic Girdle

The pelvic girdle consists of two symmetrical halves. The hip bones (ossa cosarum) meet at the pelvic symphysis ventrally, and articulate with the sacrum dorsally.


Where does the round ligament of the femur course between?

From the acetabular fossa to the fovea capitis femoris


Where does the transverse acetabular ligament course between?

Passes over the acetabular notch


very common in dogs and cats
-90% of all joint legations
-primarily caused by vehicular trauma
-occur in any direction (75% are craniodorsal)

What is it?

hip luxations


-osteoarthritis of the hip joint
-can be initiated by abnormal hip anatomy (shallow or irregularly shaped acetabulum creates joint laxity and abnormal loading)
-can occur in age
-breed predispositions (suggest genetic component)


What is it?

hip dysplasia


Which pelvic limb physes will be closed at 6 months?

Definitely open: Iliac crest (15 mos-5.5 yrs), Tuber ischiadicum (8-14 mos), Minor trochanter (8-13 mos), Tibial crest (8-10 mos)

The rest might be open or closed:
Major trochanter (6-9 mos), Distal femur (6-12 mos), proximal tibia (6-15 mos), proximal fibula (6-12 mos), distal fibula (5-13 mos), distal tibia (5-11 mos), Tuber calcanei (3-8 mos), Distal metatarsals (5-7 mos), Proximal 1st Phalanges (5-7 mos)


What are the seven joints of the pelvic limb?

Sacroiliac jt.,

coxofemoral jt.,

stifle jt.,

tarsal jt.,

metatarsophalangeal jt.,

proximal interphalangeal jt.,

distal interphalangeal jt.


Gluteus Medius Muscle O, I, A

Gives the dogs buttocks its form. 

Origin - On the outer top part of the front of the pelvises ilium. And from the ligament that connects the sacrum to the ilium.

Insertion - On the top end of the femur

Action - Pulls the limb away from the body and extends the dog’s hip joint.


Superficialis Gluteus muscle O, I, A

Origin - It originates from the first tail vertebrae, the front half of the ligament that connects the sacrum to the ischiatic tuberosity and the fascia that covers the gluteus medius. 

Insertion - About an eighth of the way down the outer surface of the femur.

Action - Pulls the limb from body and flexes hip joint.


Gracilis Muscle O, I, A

It lies on the back part of the inner side of the thigh

Origin - The middle bottom of the pelvis

Insertion - inserts into the tibias front edge and into the heel bone.

Action - Pulls limb, extends hip, flexes knee joint, extends ankle joint.


Sartorius Muscle O, I, A

Starts on the front end of the pelvis and ends on the inside of the dog’s knee. This muscle has two long muscle bands that are next to each other. A front (Cranial) part and a rear (caudal) part.

Origin - Front portion – in a line on the pelvis front edge.
Rear portion – in a line on the bottom edge of the front end of the pelvis.

Insertion - Front portion – inserts into the patella and the fascia of the knee along with the vastus medialis and the rectus femoris.
Rear Portion – The front edge of the tibia


Quadriceps muscles O, I, A

There are four muscles that make up this muscle. Vastus Lateralis, Vastus Medius, Deep Vastus Intermedius and the Rectus Femoris.

Origin - Vastus medialis – in small areas. On the inside of the femur near its upper end.
Vastus lateralis – in small areas. On the outside of the femur near its upper end.
Deep vastus intermedius – On the inside of the femur.
Rectus Femoris – in one area on the pelvis.

Insertion - All of the vastus muscles insert into their own areas of the rectus femoris then they all insert together into the patella and so also the tibia.

Action - extend stifle and flex hip


Tensor Fascae Latae Muscle O, I, A

Is a triangular shaped muscle that divides into two on its surface

Origin -The tensor facae late muscle originates on the surface of the gluteus medius at the lower edge of the front of the pelvis.

Insertion - Into the fascia that covers the thighs muscles. Therefore it also attaches indirectly into the patellar and the tibias front edge. 

Action - extends knee joint, flexes hip joint


A hamstring muscle Biceps femoris O, I, A

Big and wide muscle that consists of the superficial head and the deep head.

Origin - Superficial head - onto the ischiatic tuberosity on the outer corner, at the back part of the pelvis. And then the back third of the sacrotuberal ligament.
Deep head - onto the ischiatic tuberosity on the outer corner, at the bottom and deep into the same origin as the superficial head.

Insertion - Into the legs fascia and the patella, the upper part of the tibia, patellar ligament and the end of the heel bone (calcaneus)

Action - Extends hip joint, extends and flexes knee joint and extends ankle joint


A hamstring Muscle. Semitendinosus Muscle

forms a very small part of the thighs rear profile.

Origin - It originates on the Outside corner of the back part of the pelvis.

Insertion - It inserts about one fourth of the way down the tibia on its front edge. And on the calcaneus of the heel bone.

Action - Extends hip and ankle joint, flexes knee joint and rotates leg inwards


A hamstring Muscle. Semimembranosus Muscle O, I, A

fleshy thick muscle that has two heads.

Origin - On the back end of the pelvises bottom edge in a line.

Insertion - Inserts On the inner back corner of the femur in a vertical line and ends In two places, just before the bottom of the bone, and in a small area on the inside of the top end of the tibia.

Action - Pulls the limb towards the middle of the body, extends hip joint


Hind Adductor muscle O, I, A

There are three adductor muscles. Adductor longus, adductor magnus and the brevis muscle. These muscles are found in the deep layer of the muscles. 

Origin - They all originate on the pelvic joint via the symphysial tendon. Also Near the ischiatic arch, the ventral surface of the pubis and ventral surface of the ischium.

Insertion - Inserts into the whole lateral lip of the caudal rough face of the femur.

Action - Adduct limb and extend dogs hip and stabilizes hind leg


What makes up the acetabulum?


What are the bones of the hips and what do they do?


The pelvis is like a box

The front of the pelvis is attached to a portion of the spine called the sacrum (labeled S) by a fairly immoveable sacroiliac joint

The ilium (labeled l) is the largest weight-bearing portion of the pelvis

The hind limbs are attached to pelvis at the acetabulum (hip joint) - labeled A

The ischium (labeled Is) is the nonweight-supporting portion of the pelvis

The sciatic nerve, which is the primary nerve of the back leg, runs along the inner side of the ilium and over the top of the ischium just behind the acetabulum