BONES OF LOWER LIMB
The skeleton of the lower limb (also known as the inferior appendicular skeleton) is divided
into two functional components: the pelvic girdle and the bones of the free lower limb
The pelvic girdle (also called the bony pelvis) is a bony ring formed by:
● The sacrum
● The right and left hip bones
● These are joined anteriorly at the pubic symphysis
The pelvic girdle functions to:
● Attach the free lower limb to the axial skeleton (with the sacrum acting as a shared
structure between the axial skeleton and pelvic girdle)
● Form the skeletal framework of the lower part of the trunk
The pelvic girdle provides protection and support for the:
● Abdomen
● Pelvis
● Perineum
● Lower limbs
The bones of the free lower limb are contained within the free limb itself and specifically serve
the functional needs of the lower limb
ARRANGEMENT OF LOWER LIMB BONES
Body weight transfer in the lower limb follows this sequence:
● From the vertebral column
● Through the sacroiliac joints
● To the pelvic girdle
● From the pelvic girdle
● Through the hip joints
● To the femurs (Latin: femora)
To support erect bipedal posture:
● The femurs are oblique, directed inferomedially within the thighs
* ● This orientation places the knees adjacent and directly inferior to the trunk when
standing
● This alignment helps return the center of gravity to the vertical lines of the
supporting legs and feet
,In quadrupeds:
● The femurs are vertical
● The knees are positioned apart
● The trunk mass is suspended between the limbs
In human females, the femurs are slightly more oblique than in males this reflects the
greater width of the female pelvis
At the knee joint the distal end of each femur articulates with the patella and the tibia of
the corresponding leg
Weight is transferred from the knee joint to the ankle joint via the tibia
The fibula:
● Does not articulate with the femur
● Does not bear or transfer weight
● Serves as a site for muscle attachment
● Contributes to the formation of the ankle joint
At the ankle:
● The weight borne by the tibia is transferred to the talus
The talus:
● Acts as the keystone of the longitudinal arch of the foot
● The arch is formed by the tarsal and metatarsal bones of each foot
● It distributes weight evenly between the heel and forefoot when standing
● It provides a flexible but stable platform to support the body
, HIP BONE
The mature hip bone (Latin: os coxae) is a large, flat pelvic bone formed by the fusion of
three primary bones:
● Ilium
● Ischium
● Pubis
● Fusion occurs by the end of the teenage years
Development and ossification:
● Each of the three bones originates from its own primary center of ossification
● Five secondary centers of ossification appear later
At birth:
● The three primary bones are joined by hyaline cartilage
● In children, the bones are not fully ossified
At puberty:
● The three bones are still separated by a Y-shaped triradiate cartilage located at the
center of the acetabulum
● The ischiopubic rami fuse by approximately the 9th year of age
Fusion timeline:
● Fusion of the ilium, ischium, and pubis begins between 15 and 17 years of age
● Fusion is typically complete between 20 and 25 years of age
● In older adults, the fusion lines are usually no longer visible
Even though the hip bone is fully fused in adults:
● The terms ilium, ischium, and pubis are still used to describe the anatomical regions
of the hip bone
The medial aspect of the hip bones (bony pelvis):
● Is primarily involved with pelvic and perineal structures and functions
● Is also concerned with articulation with the vertebral column
ILIUM
The ilium:
● Forms the largest part of the hip bone
The skeleton of the lower limb (also known as the inferior appendicular skeleton) is divided
into two functional components: the pelvic girdle and the bones of the free lower limb
The pelvic girdle (also called the bony pelvis) is a bony ring formed by:
● The sacrum
● The right and left hip bones
● These are joined anteriorly at the pubic symphysis
The pelvic girdle functions to:
● Attach the free lower limb to the axial skeleton (with the sacrum acting as a shared
structure between the axial skeleton and pelvic girdle)
● Form the skeletal framework of the lower part of the trunk
The pelvic girdle provides protection and support for the:
● Abdomen
● Pelvis
● Perineum
● Lower limbs
The bones of the free lower limb are contained within the free limb itself and specifically serve
the functional needs of the lower limb
ARRANGEMENT OF LOWER LIMB BONES
Body weight transfer in the lower limb follows this sequence:
● From the vertebral column
● Through the sacroiliac joints
● To the pelvic girdle
● From the pelvic girdle
● Through the hip joints
● To the femurs (Latin: femora)
To support erect bipedal posture:
● The femurs are oblique, directed inferomedially within the thighs
* ● This orientation places the knees adjacent and directly inferior to the trunk when
standing
● This alignment helps return the center of gravity to the vertical lines of the
supporting legs and feet
,In quadrupeds:
● The femurs are vertical
● The knees are positioned apart
● The trunk mass is suspended between the limbs
In human females, the femurs are slightly more oblique than in males this reflects the
greater width of the female pelvis
At the knee joint the distal end of each femur articulates with the patella and the tibia of
the corresponding leg
Weight is transferred from the knee joint to the ankle joint via the tibia
The fibula:
● Does not articulate with the femur
● Does not bear or transfer weight
● Serves as a site for muscle attachment
● Contributes to the formation of the ankle joint
At the ankle:
● The weight borne by the tibia is transferred to the talus
The talus:
● Acts as the keystone of the longitudinal arch of the foot
● The arch is formed by the tarsal and metatarsal bones of each foot
● It distributes weight evenly between the heel and forefoot when standing
● It provides a flexible but stable platform to support the body
, HIP BONE
The mature hip bone (Latin: os coxae) is a large, flat pelvic bone formed by the fusion of
three primary bones:
● Ilium
● Ischium
● Pubis
● Fusion occurs by the end of the teenage years
Development and ossification:
● Each of the three bones originates from its own primary center of ossification
● Five secondary centers of ossification appear later
At birth:
● The three primary bones are joined by hyaline cartilage
● In children, the bones are not fully ossified
At puberty:
● The three bones are still separated by a Y-shaped triradiate cartilage located at the
center of the acetabulum
● The ischiopubic rami fuse by approximately the 9th year of age
Fusion timeline:
● Fusion of the ilium, ischium, and pubis begins between 15 and 17 years of age
● Fusion is typically complete between 20 and 25 years of age
● In older adults, the fusion lines are usually no longer visible
Even though the hip bone is fully fused in adults:
● The terms ilium, ischium, and pubis are still used to describe the anatomical regions
of the hip bone
The medial aspect of the hip bones (bony pelvis):
● Is primarily involved with pelvic and perineal structures and functions
● Is also concerned with articulation with the vertebral column
ILIUM
The ilium:
● Forms the largest part of the hip bone
