07 Appendicular Skeleton Pelvic Girdle And Lower Limbs

The lower portion of the appendicular skeleton consists of the pelvic girdle and the lower extremities.

According to your text, the term “pelvic girdle” refers only to the left and right ossa coxae (each of which is composed of the ilium, ischium, and pubis). However, some texts also include the sacrum.

Ilium

Iliac crest

Acetabulum

The pelvis consists of the two ossa coxae (singular = os coxae), the sacrum, and the coccyx.

The pelvic girdle protects and supports several abdominal organs

Each os coxae consist of three bones fused together

Acetabulum

Each os coxae (hip bone) consists of the ilium, ischium, and pubis. These three bones fuse between 13-15 years of age.

Acetabulum

The ilium is the largest and uppermost of the pelvic bones

The auricular surface is the portion of the ilium that articulates with the sacrum

The iliac crest terminates anteriorly at the anterior superior iliac spine.

This person is actually pressing on the anterior superior iliac spine.

The iliac crest terminates posteriorly at the posterior superior iliac spine

Bone marrow biopsy in posterior portion of the iliac crest

The ischium is the posterior-inferior component of the os coxae. It is the portion of the pelvis we sit on.

Note the ischial tuberosity of the ischium on which we sit.

The pubis is the anterior component of the os coxae.

WHAT PORTION OF YOUR PELVIS IS MOST PROXIMAL TO YOUR BELT?

A COCCYX

B SACRUM

C ILIUM

D ISCHIUM

E PUBIS

The false pelvis (shown in green) is the upper portion of the pelvic basin and is enclosed by the wing-like sides of the flared iliac bones.

The true pelvis (shown in pink) is the lower portion of the pelvic basin and it encloses the pelvic cavity and forms a deep narrower region that contains the pelvic organs.

During birth (parturition) the fetus passes through the true pelvis during a normal vaginal delivery

Pelvimetry is the measurement of the size/shape of the pelvic outlet

Inferior view

Fetus’ head ready to pass through the true pelvis and pelvic outlet during birth

The squatting position can increase the diameter of the true pelvis

• In our society we are not used to squatting, and it can be a difficult position to assume.

• You can practice!

Birth (parturition) in the squatting position with support from partner.

Supported squatting position for childbirth

During pregnancy there is a special hormone called relaxin that is released by the corpus luteum of the ovary

Relaxin loosens the symphysis pubis and the sacroiliac joint to increase the diameter of the true pelvis and pelvic outlet to facilitate parturition.

Male

Female

Note the female pelvis has wider flair of iliac crests, has a more spherical true pelvis, and the pubic arch is wider than the male

Articular surface of pubic bones at symphysis pubis

Articular surface of pubic bones at symphysis pubis

The femur is the only bone of the thigh. However, we will also discuss the patella. The femur is the strongest bone in the body.

It is a useful study technique to compare and contrast the bones of the lower extremity with their counterparts in the upper extremity.

The proximal rounded head of the femur articulates with the acetabulum of the os coxae. Below the head is a constricted neck that is a common site for fractures of the femur in elderly persons.

A tiny ligament connects the acetabulum to the fovea in the proximal head of the femur

shaft

The constricted neck joins the shaft of the femur..

The shaft of the femur has a slight medial bow to bring the knee joints more in line with the body’s plane of gravity. This degree of convergence is more pronounced in females.

Because of a female’s wider hips the medial bow of the femur is more noticeable and the knees are in closer proximity to each other.

It is technically incorrect to say that an elderly person, usually a female, has broken her “hip”. It is more accurate to state that they broke the neck of their femur.

The greater trochanter, which develops because of pulling stress on the periosteum, is found on the proximal lateral portion of the femur.

Features of the femur

The patella is a sesamoid bone positioned on the anterior surface of the femur. It does NOT articulate with the tibia.

Patella on femur

Note largest facet is lateral when apex is inferior.

WHICH OF THE FOLLOWING DOES NOT ARTICULATE WITH THE FEMUR?

A TIBIAL TUBEROSITY

B PUBIS

C SESAMOID BONE

D ILIUM

E ISCHIUM

The lower leg, or crural region, contains two bones: the tibia, which is a weight-bearing bone, and the fibula, which not a weight-bearing bone but is important for muscle attachment.

posterioranterior

Interosseous membrane

The tibia is the larger and more medial of the two bones of the crural region. At its proximal end the tibia articulates with the femur. At its distal end the tibia articulates with the talus.

The intercondylar eminence of the tibia is just a small stabilizing bump in the center of the tibial plateau.

The medial and lateral condyles of the tibia articulate with the medial and lateral condyles of the distal femur.

Anterior Posterior

Anterior view

The fibula and the tibia at their proximal ends form the superior tibiofibular joint

The tibial tuberosity of the tibia is the distal attachment site of the patellar ligament.

About one finger’s width below the tibial tuberosity, and just medial, is a flat surface on the anterior proximal portion of the tibia where interosseous infusions of life-saving fluids can be administered by punching a large needle through the bone into the medullary cavity. This is easiest in children under five years of age.

An interosseous infusion needle used for punching through bone

Interosseous infusion

Interosseous infusion of life-saving fluid works best in children under five years of age. Unlike veins, which may collapse when blood pressure falls, the medullary cavity of the tibia ALWAYS stays open.

The anterior crest of the tibia can be easily palpated. The medial malleolus is at the distal end of the tibia and forms a medial knob that is also easily palpated. It is erroneously referred to as an ankle bone.

Anterior Posterior

A child receiving life-saving fluid via interosseous infusion into the medial malleolus of the tibia. As was stated previously, such I.O. infusions work best in children under five years of age.

for interosseous (I.O.) infusion of life-saving fluids

So both the proximal AND distal ends of the tibia can be used for I.O. infusions.

The inferior portions of the tibia and fibula articulate to form the inferior tibiofibular joint

The fibula does not articulate with the femur but it does with the talus. The distal end of the fibula forms the lateral malleolus, which is easily palpated on the lateral side of the ankle. It is erroneously referred to as an ankle bone.

There are seven tarsal bones that contribute to the ankle. We will only discuss two of these. The talus is the most superior of the tarsal bones and it articulates with the malleoli of the tibia and fibula. The calcaneus forms the prominence of the heel.

The calcaneus forms the prominence of the heel. It also serves as an attachment site for large calf muscles.

The foot contains five metatarsal bones, with #1 leading to the great toe. All of the toes (digits) contain three bones, except for the great toe (digit #1), that only contains two. These bones in the toes are called phalanges.

There are three arches that support the weight of the body and provide leverage when walking: transverse arch, medial longitudinal arch, and lateral longitudinal arch.

The ligamentous medial and lateral longitudinal arches and the transverse arch of the foot are maintained primarily by the foot bones themselves.

Talipes or clubfoot is a congenital malformation in which the sole of the foot is twisted medially. Read about other foot pathologies in the clinical view in the text.

ACCORDING TO THE CLINICAL VIEW IN YOUR TEXT ON PATHOLOGIES OF THE FOOT, WHICH OF THE FOLLOWING CONDITIONS IS OFTEN SEEN IN PERSONS WITH POLIOMYELITIS?

A PES PLANUS

B TALIPES EQUINOVARUS

C PES CAVUS

D METATARSAL STRESS FRACTURE

E CLUBFOOT

Fracture of the pelvis in a child caused by blunt trauma. Open or closed fractures of the pelvis are associated with the risk of life-threatening blood loss.

Indirect forces can fracture the pelvis

Closed fractures of the pelvis may occur in elderly persons who suffer from osteoporosis.

Since it is a complete circle, stress to the pelvis usually results in fractures in two places when stress is applied.

Fractures of the pelvis can be associated with life-threatening blood loss.

Umbilicus Bleeding into tissues

Rapidly restoration of normal anatomy to control pelvic fracture bleeding is essential.

What many persons refer to as a “hip fracture” is actually a fracture of the neck of the femur.

Fractures of the neck of the femur most commonly occur in elderly post-menopausal females with osteoporosis.

Risk-taking young adults can also fracture the neck of the femur in traumatic accidents.

Teenage male slipped on ice and suffered break in neck of femur

Repair of the teenage male’s femoral neck fracture with stabilizing screws.

Risk-taking male snowboarder’s chest X-ray after fracture of his femoral neck.

Diaphragm

Heart

?

Fracture of the neck of the femur in risk-taking male snowboarder.

This has to be painful!

His repair with a screwed on plate to the femoral shaft with an attached screw into the femoral neck.

Close-up of screw into femoral neck and head

Severe trauma is needed to fracture the femoral shaft in young adults.

Since severe trauma is needed to fracture the massive femur in young adults, such fractures are often open.

Open or closed femoral fractures can be associated with life-threatening blood loss.

Excessive internal bleeding in femoral shaft fracture

knee

Thigh

Femoral shaft fractures are of special concern because the large elastic muscles which span the femur can pull jagged ends of the fractured bone through the muscles, blood vessels, and nerves causing on-going damage after the original fracture!

A Hare Traction Splint can stop this on-going trauma by pulling on the leg.

The Hare Traction Splint can be removed in the Operating Room after the femoral fracture is repaired with a metal plate and screws. These plates and screws can be left in place for the patient’s lifetime, or removed after about a year.

X-ray of comminuted patellar fracture

Repair of comminuted patellar fracture with pins and wire.

Note runner (see his helmet) coming in leading with his knee

The baseman is experiencing a tibia/fibula fracture and doesn’t know it yet. He is still trying to make the play.

Close-up of collusion of knee with baseman’s tibia/fibula.

A former student of mine, who was playing as a baseman in a coed softball game behind the HYPER building while wearing cleats, suffered a similar tibia/ fibula fracture.

The tibial nail or rod was inserted into his medullary cavity just below his tibial tuberosity so it extended through the fracture site and was screwed in place.

The nail or rod was inserted into the tibial medullary cavity through a hole drilled just below the tibial tuberosity.

Tibial rod or nail in place, inserted past the site of fracture, and screwed in place. Note that the fibula is left as is as it is not a weight-bearing bone.

Fixation of the tibial rod or nail in place with screws.

View of the healed tibia and fibula of the male softball player mentioned earlier who sustained a tibia/fibula fracture behind the HYPER building. This is one year after the injury. He opted to have the rod (nail) removed the next week. The rod is removed by screwing a device into the proximal end of the rod and they using a slap hammer to pull it out. It is essential that all the screws are removed before the hammering begins!

Long jumper experiencing right tibial fracture on takeoff.

Close-up of right tibial fracture that occurred on takeoff

Open fracture of tibia upon landing

WHICH OF THE FOLLOWING IS TYPICALLY ASSOCIATED WITH POTENTIALLY FATAL HYPOVOLEMIC SHOCK?

A ILIAC FRACTURE

B POTTS FRACTURE

C CRURAL FRACTURE

D COLLES FRACTURE

E CRUCIFIXION

Fractures in the ankle region were common before better boots were designed. Now skiers are more likely to suffer boot-top fractures of the tibia/fibula or dislocate the knee.

A Pott’s fracture occurs when a side-ways force causes both malleoli to fracture.

Pott’s fracture

Calcaneal fracture

Repair of calcaneal fracture

All gangrenous (dead) tissue must be surgically amputated. However, a surgeon can do it with style.

Note that at the end of the surgery the foot has retained its symmetry and aesthetics.