Bones and Joints - Anatomy of Lower Extremity

Bones & Joints of the Bones & Joints of the Lower ExtremitiesLower Extremities

Reynaldo V. Lopez, M.D.Senior LecturerDepartment of AnatomyAngeles University School of Medicine

Pelvic GirdlePelvic Girdle

• Attaches lower limbs to the spine

• Supports visceral organs

• Attaches to the axial skeleton by strong ligaments

• Acetabulum is a deep cup that holds the head of the femur

• Lower limbs have less freedom of movement

•Are more stable than the arm

Pelvic GirdlePelvic Girdle

• Consists of paired hip bones (coxal bones)

• Hip bones unite anteriorly with each other

• Articulates posteriorly with the sacrum

Bony PelvisBony Pelvis

• A deep, basin-like structure

• Formed by coxal bones, sacrum, and coccyx

Bony PelvisBony Pelvis

Coxal BonesCoxal Bones

• Consist of three separate bones in childhood

• Ilium, ischium, and pubis

• Bones fuse – retain separate names to regions of the coxal bones

• Acetabulum – deep hemispherical socket on lateral pelvic surface

IliumIlium

• Large, flaring bone

• Forms the superior region of the coxal bone

• Site of attachment for many muscles

• Articulation with the sacrum forms sacroiliac joint

IschiumIschium

• Forms posteroinferior region of the coxal bone

• Anteriorly – joins the pubis

• Ischial tuberosities – the strongest part of the hip bone

PubisPubis

• Forms the anterior region of the coxal bone

• Lies horizontally in anatomical position

• Pubic symphysis

• The two pubic bones are joined by fibrocartilage at the midline

Lateral and Medial Views of the Hip BoneLateral and Medial Views of the Hip Bone

True and False PelvesTrue and False Pelves

• Bony pelvis is divided into two regions

• False (greater) pelvis – bounded by alae of the iliac bones

• True (lesser) pelvis – inferior to pelvic brim

•Forms a bowl containing the pelvic organs

True and False PelvesTrue and False Pelves

Pelvic Structures and ChildbearingPelvic Structures and Childbearing

• Major differences between male and female pelves

• Female pelvis is adapted for childbearing

•Pelvis is lighter, wider, and shallower than in the male

•Provides more room in the true pelvis

Female and Male PelvesFemale and Male Pelves

Hip JointHip Joint

• The bones of the hip are the femur (the thighbone) and the pelvis.

• The top end of the femur is shaped like a ball called the femoral head.

• The femoral head fits into a round socket on the side of the pelvis called the acetabulum.

Hip JointHip Joint

• A small ligament connects the very tip of the femoral head to the acetabulum.

• This ligament, called the ligamentum teres, doesn't play a role in controlling hip movement like the main hip ligaments.

Hip JointHip Joint

• A special type of ligament forms a unique structure inside the hip called the labrum.

• The labrum is attached almost completely around the edge of the acetabulum.

• The shape and the way the labrum is attached create a deeper cup for the acetabulum socket.

The Lower LimbThe Lower Limb

• Carries the entire weight of the erect body

• Bones of lower limb are thicker and stronger than those of upper limb

• Divided into three segments

• Thigh, leg, and foot

ThighThigh

• The region of the lower limb between the hip and the knee

• Femur – the single bone of the thigh

• Longest and strongest bone of the body

• Ball-shaped head articulates with the acetabulum

Structures of the FemurStructures of the Femur

PatellaPatella

• Triangular sesamoid bone

• Imbedded in the tendon that secures the quadriceps muscles

• Protects the knee anteriorly

• Improves leverage of the thigh muscles across the knee

Knee JointKnee Joint

• The end of the femur joins the top of the tibia to create the knee joint.

• Two round knobs called femoral condyles are found on the end of the femur.

• These condyles rest on the top surface of the tibia.


• This surface is called the tibial plateau.

• The outside half is called the lateral tibial plateau, and the inside half is called the medial tibial plateau.

• The patella glides through a special groove formed by the two femoral condyles called the patellofemoral groove.


• Capsule of knee joint

• Covers posterior and lateral aspects of the knee

• Covers tibial and femoral condyles

• Does not cover the anterior aspect of the knee

•Anteriorly – covered by three ligaments

–Patellar, medial, and lateral retinacula

Anterior View of KneeAnterior View of Knee

Figure 9.12c


• Ligaments of the knee joint

• Become taut when knee is extended

• 4 extracapsular ligaments:

•Fibular and tibial collateral ligament

•Oblique popliteal ligament

•Arcuate popliteal ligament


• Two extracapsular ligaments are found on either side of the knee joint.

• They are the medial collateral ligament (MCL) and the lateral collateral ligament (LCL).

• The MCL and LCL prevent the knee from moving too far in the side-to-side direction.


• Intracapsular ligaments

• Cruciate ligaments – cross each other like an “X”

• Each runs from the proximal tibia to the distal femur

• anterior cruciate ligament (ACL) in front,

• posterior cruciate ligament (PCL) in back.


• The ACL and PCL control the front-to-back motion of the knee joint.


• Two special types of ligaments called menisci sit between the femur and the tibia.

• Functions:

(1) they work like a gasket to spread the force from the weight of the body over a larger area

(2) they help the ligaments with stability of the knee.


• The largest tendon around the knee is the patellar tendon.

• This tendon connects the patella (kneecap) to the tibia.

• This tendon covers the patella and continues up the thigh.


• There it is called the quadriceps tendon since it attaches to the quadriceps muscles in the front of the thigh.


• The hamstring muscles on the back of the leg also have tendons that attach in different places around the knee joint.

LegLeg

• Refers to the region of the lower limb between the knee and the ankle

• Composed of the tibia and fibula

• Tibia – more massive – medial bone of the leg

•Receives weight of the body from the femur

• Fibula – stick-like – lateral bone of the leg

• Interosseous membrane – connects the tibia and fibula

LegLeg

• Tibia articulates with femur at superior end

• Forms the knee joint

• Tibia articulates with talus at the inferior end

• Forms the ankle joint

• Fibula does not contribute to the knee joint

• Stabilizes the ankle joint

Structures of the Tibia and FibulaStructures of the Tibia and Fibula

Ankle JointAnkle Joint

• The ankle joint is formed by the connection of three bones.

• The ankle bone is called the talus.

• The top of the talus fits inside a socket that is formed by the lower end of the tibia and the fibula.

• The bottom of the talus sits on the heelbone, called the calcaneus.


• The talus works like a hinge inside the socket to allow your foot to move up (dorsiflexion) and down (plantarflexion).


• Woodworkers and craftsmen are familiar with the design of the ankle joint.

• They use a similar construction, called a mortise & tenon, to create stable structures.


• 3 ligaments make up the lateral ligament complex on the lateral side of the ankle.

• These include the:

• anterior talofibular ligament (ATFL)

• calcaneofibular ligament(CFL)

• posterior talofibular ligament (PTFL).


• A thick ligament, called the deltoid ligament, supports the medial side of the ankle.


• The large Achilles tendon is the most important tendon for walking, running, and jumping.

• It attaches the calf muscles to the calcaneus and allows us to raise up on our toes.


• The posterior tibial tendon attaches one of the smaller muscles of the calf to the underside of the foot.

• This tendon helps support the arch and allows us to turn the foot inward.

• The anterior tibial tendon allows us to raise the foot.


• Two tendons run behind the lateral malleolus of the ankle.

• These two tendons, called the peroneals, help turn the foot down and out.

The FootThe Foot

• Foot is composed of:

• Tarsus, metatarsus, and the phalanges

• Important functions

• Supports body weight

• Acts as a lever to propel body forward when walking

• Segmentation makes foot pliable and adapted to uneven ground

TarsusTarsus

• Makes up the posterior half of the foot

• Contains seven bones called tarsals

• Body weight is primarily borne by the talus and calcaneus

MetatarsusMetatarsus

• Consists of five small long bones called metatarsals

• Numbered 1–5 beginning with the hallux

(great toe)

• First metatarsal supports body weight

Phalanges of the ToesPhalanges of the Toes

• 14 phalanges of the toes

• Smaller and less nimble than those of the fingers

• Structure and arrangement are similar to phalanges of fingers

• Except for the great toe, each toe has three phalanges

•Proximal, middle, and distal

Bones of the FootBones of the Foot

Arches of the FootArches of the Foot

• Foot has three important arches

• Medial and lateral longitudinal arch

• Transverse arch

• Arches are maintained by:

• Interlocking shapes of tarsals

• Ligaments and tendons

Arches of the FootArches of the Foot

Bones and Joints - Anatomy of Lower Extremity

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