Veterinary Dog Anatomy

Note: All the notes provided us from gcvs 

recomended book Guide To The Dissection Of Dog By Howard E. Evans, PhD 

Lecture no 5

BONES OF THE PELVIC LIMB

Veterinary Anatomy  GCVS 1st semester

BONES OF THE PELVIC LIMB

The pelvic girdle,or pelvis, of the dog consists

of two hip bones, which are united at the sym-physis pelvismidventrally and join the sacrum

dorsally. Each hip bone, or os coxae,is formed

by the  fusion of three primary bones and the

addition of a fourth in early life The

largest and most cranial of these is the ilium,

which articulates with the sacrum. The ischium

is the most caudal, whereas the pubisis located

ventromedial to the ilium and cranial to the large

obturator foramen. The acetabulum,a socket, is

formed where the three bones meet. It receives

the head of the femur in the formation of the hip

joint. The small  acetabular bone,which helps

form the acetabulum, is incorporated with the

ilium, ischium, and pubis when they fuse (about

the third month).

The pelvic canalis short ventrally but long

dorsally. Its lateral wall is composed of the ilium,

ischium, and pubis. Dorsolateral to the skeletal

part of the wall, the pelvic canal is bounded by

soft tissues. The pelvic inletis limited laterally

and ventrally by the arcuate line of the ilium.

Its dorsal boundary is the promontory of the sa-crum. The pelvic outletis bounded ventrally by

the ischiatic arch(the ischiatic arch is formed

by the concave caudal border of the two ischii);

mid-dorsally by the first caudal vertebra; and lat-erally by the superficial gluteal muscle, muscles

of the pelvic diaphragm, and the sacrotuberous

ligament.

Os Coxae

1. The iliuma flat

bone presenting two surfaces and three borders,

forms the cranial one half to three fifths of the

os coxae. It can be divided into a wide cranial

part, which is concave laterally and known as

the wing,and a narrow, laterally compressed

caudal part, the body.

The cranial border is arciform and usually

roughened and is more commonly known as the

iliac crest.It is thin but gradually increases in

thickness dorsally. The angle of junction of the

iliac crest with the ventral border is known as

the cranial ventral iliac spine, which provides a

place of origin for both bellies of the sartorius

and a part of the tensor fasciae latae. The tuber

coxaeis composed of the cranial ventral iliac

spine and the adjacent part of the ventral border

of the wing of the ilium. The rest of the ventral

border is concave. It ends in the lateral area for

the rectusfemoris just cranial to the

acetabulum.

The dorsal border of the ilium is broad and mas-sive. The junction of the dorsal border with the

iliac crest forms an obtuse angle that is a rounded

prominence, the cranial dorsal iliac spine.Cau-dal to the cranial dorsal iliac spine is the wide but

blunt caudal dorsal iliac spine.The two spines

and intervening bone make up the tuber sacrale,

which occupies nearly half the length of the dor-sal border of the ilium. The caudal half of the dor-sal border is gently concave. It forms the greater

ischiatic notchand also helps form the ischiatic

spine, which is dorsal to the acetabulum.

The external or gluteal surface(Fig. 2-33) of the

wing of the ilium is nearly flat caudally and con-cave cranially, where it is limited by the iliac crest.

The dorsal part of this concave area is bounded by

a heavy ridge, the tuber sacrale. The gluteal sur-face is rough ventrocranially. The middle gluteal

and a portion of the deep gluteal attach here.

The internal or sacropelvic surface(Fig. 2-34) of

the wing of the ilium presents a smooth, nearly flat

area that provides attachment for the iliocostalis, longissimus, and the quadratus  lumborum

muscles. The auricular surfaceis rough and ar-ticulates with a similar surface of the sacrum,

forming the sacroiliac joint. The arcuate lineis

located along the ventromedial edge of the sacro-pelvic surface of the body of the ilium and runs from

the auricular surface to the iliopubic eminence of

the pubis. The tendon of the psoas minor attaches

along the medial aspect of this line.

2. The ischium consists

of tuberosity, body, table, and ramus. It forms

the caudal part of the os coxae and enters into

the formation of the acetabulum, obturator fo-ramen, and symphysis pelvis. Its caudal border

consists of the ischiatic tuberosity laterally and

one half of the ischiatic arch medially. The ischi-atic tuberosityis the thick caudolateral margin

of the bone. The lateral angle of the tuber is en-larged and hooked; it furnishes attachment for

the sacrotuberous ligament. The medial angle

is rounded. The ventral surface is the place of

origin for the biceps femoris, semitendinosus,

and semimembranosus. The crus of the penis

and the muscle that surrounds it also attach to

the ischiatic tuberosity medially.

The body of the ischiumis the part lateral to the

obturator foramen. The ischiatic spineis a rounded

crest dorsal to the acetabulum, where the body of

ILIUM, ISCHIUM,

PUBIS

Hip

Coxa

FEMUR

Thigh

TIBIA, FIBULA

Leg

Crus

PES

Tarsus

Metatarsus

Digits

Flexor

surface

Flexor

surface

Flexor

surface

Flexor

surface

Sacroiliac joint

Hip joint

Stifle joint

Tarsal joints

Digital joints

of left pelvic limb.

the ischium meets the ilium. The coccygeus at-taches here. Caudal to this spine the border of the

ischium is depressed and marked by a series of low

ridges produced by the tendon of the internal ob-turator. This area is known as the lesser ischiatic

notch The gemelli arise from the

lateral surface adjacent to the lesser ischiatic notch.

The ramusof the ischium is the thin and wide

medial part of the ischium. It is bounded laterally

by the obturator foramen and blends caudally

with the body of the ischium. The ramus meets

its fellow at the symphysis and is fused with the

pubis cranially. The ischiatic tableis the flat por-tion where the ramus meets the body (Fig. 2-34). It

faces dorsally and is the site of origin of the inter-nal obturator muscle. The quadratus femoris and

the external obturator arise from its ventral sur-face. The ischiatic archis formed by the medial

portion of the caudal border of each ischium.

3. The pubis extends from

the ilium and ischium laterally to the symphysis

medially and consists of a body and two rami.

The bodyis located cranial to the obturator fora-men. The cranial ramusextends from the body to

the ilium and enters into the formation of the ace-tabulum. The caudal ramusfuses with the ischial

ramus at the middle of the pelvic symphysis. The

ventral surface of the pubis and adjacent ischial

ramus serve as origin for the gracilis, the adduc-tor, and the external obturator. The dorsal surface

gives rise to a small part of the internal obturator

and the levator ani. The obturator sulcus,a groove

for the obturator nerve, is located at the cranial

end of the obturator foramen and passes dorsally

over the pelvic surface of the body of the bone.

The iliopubic eminenceprojects from the cranial

border of the cranial ramus of the pubic bone. The

pectineus attaches to it. The pubic tubercleproj-ects cranially from the pubis on the midline. The

roughened cranial border of the pubis between

the iliopubic eminence and the pubic tubercle is

the pecten,to which the abdominal muscles at-tach by means of a prepubic tendon to be dissected

later. The prepubic tendon is composed primarily

of the tendons of the paired rectus abdominis and

pectineus muscles.

The acetabulum  is a cavity

that receives the head of the femur. Its articular

surface is semilunar and is composed of parts

of the ilium, ischium, and, in young animals,

the acetabular bone In the adult the

acetabular bone is fused imperceptibly with the

pubis, ischium, and ilium. The circumference of

the articular surface is broken at the caudomedial

part by the acetabular notch.The acetabular

fossais formed by the ischium and the acetabular

bone. The ligament of the head of the femur at-taches in this fossa. The fossa and the notch are the

nonarticular parts of the acetabulum. The two

sides of the notch are connected by the transverse

acetabular ligament.

The obturator foramenis closed in life by the

obturator membrane and the external and internal

obturator muscles that the membrane separates.

Posted in: 1st semester