Learning Anatomy - Bones of the Lower Limb

Welcome to the first class on Learning Anatomy (Gross Anatomy )

We would start with the bones of the lower limb.

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Hip Bones

The hip bone (ox coxae) is a large flat pelvic bone formed by the fusion of three important bones which vary in size and thickness. They are

1. Ilium
2. Ischiim
3. Pubis

[credits ](https://commons.m.wikimedia.org/wiki/File:Coxal_bone_(ilium,_ischium_and_pubis)

The three bones are joined together to form acetabulum, the inferior part of the ilium , the antero-inferior part of the ishium and the postero-lateral part of pubis.

Ilium

The largest part of the hip bone and contributes about 2/5 of the acetabulum. Ilium has a thick medial portion. Its a winglike structure called the alae which is a broad surface for attachment of fleshy muscles.

Its iliac crest serve as a protective number and its important site for aponeurotic attachment for thin, sheet-like muscles and deep fascia.

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Ischium

The ishium is a rough bony structure in the hip bone. Its inefromedial boundary forms the Obturator foramen combined with the Pubis.

Ishium has one body and one ramus, the ramus joins with the pubis ramus to form the ischiopubic ramus which is a constituent of the Obturator Foramen.

The Ischium has a large tuberosity called the Ischial Tuberosity. You sit on on your tuberosity combined with fibrofatty tissues. Ischial spine is also present as it's a bony projection which ligaments attach to, to form Greater and lesser sciatic foramen.

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Pubis

Pubis is the anterior bone of of the hip bone. It has a body and two rami. Its inferior ramus forms the ischiopubic ramus and its superior rami forms the acetabulum.

Pubis joins with the pubis of the other hip bone to form the Pubic Symphysis.

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Obturator Foramen

This is a large oval, round or irregular opening in the coxae. Its boundaries are formed by the pubis and Ischium and their rami. Its usually closed by a membrane with a small gap left open for the passage of Obturator Nerve and Vessels.

Its external surface also provides attachment of fleshy muscles.

Acetabulum

This is a large cup-shaped cavity or socket on the lateral aspect of the hip bone that unites and articulates with the head of femur to form the hip joint.

All there bones of the hip combine to form the acetabulum. On its surface, there is a large depression called the Acetabular Fossa filled with fat pads.

Femur

The femur is the largest, strongest and heaviest bone in the human body. It transmits weight from the hip bone to the tibia when an individual is standing. Its length is 1/4 of the human height and it consists of a head and neck (at its proximal end), shaft and condyles (at its distal end which articulates with the tibia).

Landmarks on Femur

• Greater tronchanter

• Lesser trochanter

• Intertrochanteric line

• Head

• Neck

• Linea Aspera

• Epicondyles

• Adductor Tubercles

• Pectineal Line

• Gluteal Tuberosity

• Spiral Line

• Intercondylar Fossa

• Suprocondylar Lines

All these landmarks provide attachment for fleshy muscles

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Tibia

This bony structure is located at the anterior-medial side of the leg nearly parallel to the fibula. Second largest bone in the body and transmit weight from the femur to the foot.

Tibia forms the Shin of the Leg as its Anterior border is quite prominent. It also has its own condyles for articulation with the femur.

Landmarks of Tibia

• The Condyles

• Soleal Line

• Interosseous Membrane that runs from its lateral side

• Tibial Tuberosity

• Gerdys Tubercle

• Fibular Notch ( where it articulates with the fibular)

• Medial Malleolus (Part of the Ankle Joint)

Some of the landmarks provide attachments of fleshy muscles

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Fibular

This bone is firmly attached to the tibia and has no function in weight bearing. It only serves as muscle attachments. Eight muscles originate from it, only one attaches to it. This would be discussed as the class progresses.

Fibular shaft is twisted and marked for muscular attachment with its transverse section triangular.

Landmarks on Fibular

• Lateral Malleolus (Part of the Ankle Joint)

• Head

• Neck

Head, Neck and Shaft all provide attachments for fleshy muscles

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Bones of the Foot

The bones of the foot include the tarsus, metatarsus, and phalanges. We gave 7 tarsal bones, 5 metatarsals and 14 phalanges.

Tarsus

It consists of 7 bones which are the talus, calcaneus, cuboid, navicular, and the three cuneiforms making it 7 bones in total.

Talus is usually the bone in which the Tibial and fibular articulates at their distal ends. It transmit weight from the tibial to the calcaneus

Calcaneus transmits weight from the talus to the floor and to the forefoot. It also provides attachment for fleshy muscles

Navicular and Cuneiforms provide attachment for fleshy muscles and also make up the arch of the foot

Metatarsus

We have 5 metatarsus which articulates the phalanges and the tarsus bones.

The first metatarsal bone is stout and shorter than the rest while the second metatarsal is the longest.

Phalanges

We have 14 phalanges bone, the first digit having just 2 phalanges while the last 4 have 3 phalanges bones each.

The Phalanges of the first toe is called the Hallux

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Clinical Correlates

• Fractures of the Hip bone

• Coxa Vara and Coxa Valga

• Dislocation

• Fractures of the Femur

• Fractures of the Tibia

• Fractures of the Fibular

• Fractures of the Talar

• Calcaneal Fracture

• Metatarsals Fracture

References

Teachmeanatomy

Opentextbc

earthslab

Next Lesson we would talk about the Venous Drainage and the Fascia on the Lower Limb