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The sacral promontory    is the anterior lip of the superior base of the sacrum. Lateral to this is the roughened auricular surface, which joins with the ilium portion of the hipbone to form the immobile sacroiliac joints of the pelvis. Passing inferiorly through the sacrum is a bony tunnel called the sacral canal    , which terminates at the sacral hiatus    near the inferior tip of the sacrum. The anterior and posterior surfaces of the sacrum have a series of paired openings called sacral foramina    (singular = foramen) that connect to the sacral canal. Each of these openings is called a posterior (dorsal) sacral foramen    or anterior (ventral) sacral foramen    . These openings allow for the anterior and posterior branches of the sacral spinal nerves to exit the sacrum. The superior articular process of the sacrum    , one of which is found on either side of the superior opening of the sacral canal, articulates with the inferior articular processes from the L5 vertebra.

The coccyx, or tailbone, is derived from the fusion of four very small coccygeal vertebrae (see [link] ). It articulates with the inferior tip of the sacrum. It is not weight bearing in the standing position, but may receive some body weight when sitting.

Sacrum and coccyx

This figure shows the structure of the sacrum and coccyx. The left panel shows the vertebral column with the sacrum and coccyx highlighted in pink. The middle panel shows the anterior view and the right panel shows the posterior view of the sacrum and coccyx.
The sacrum is formed from the fusion of five sacral vertebrae, whose lines of fusion are indicated by the transverse ridges. The fused spinous processes form the median sacral crest, while the lateral sacral crest arises from the fused transverse processes. The coccyx is formed by the fusion of four small coccygeal vertebrae.

Intervertebral discs and ligaments of the vertebral column

The bodies of adjacent vertebrae are strongly anchored to each other by an intervertebral disc. This structure provides padding between the bones during weight bearing, and because it can change shape, also allows for movement between the vertebrae. Although the total amount of movement available between any two adjacent vertebrae is small, when these movements are summed together along the entire length of the vertebral column, large body movements can be produced. Ligaments that extend along the length of the vertebral column also contribute to its overall support and stability.

Intervertebral disc

An intervertebral disc    is a fibrocartilaginous pad that fills the gap between adjacent vertebral bodies (see [link] ). Each disc is anchored to the bodies of its adjacent vertebrae, thus strongly uniting these. The discs also provide padding between vertebrae during weight bearing. Because of this, intervertebral discs are thin in the cervical region and thickest in the lumbar region, which carries the most body weight. In total, the intervertebral discs account for approximately 25 percent of your body height between the top of the pelvis and the base of the skull. Intervertebral discs are also flexible and can change shape to allow for movements of the vertebral column.

Each intervertebral disc consists of two parts. The anulus fibrosus    is the tough, fibrous outer layer of the disc. It forms a circle (anulus = “ring” or “circle”) and is firmly anchored to the outer margins of the adjacent vertebral bodies. Inside is the nucleus pulposus    , consisting of a softer, more gel-like material. It has a high water content that serves to resist compression and thus is important for weight bearing. With increasing age, the water content of the nucleus pulposus gradually declines. This causes the disc to become thinner, decreasing total body height somewhat, and reduces the flexibility and range of motion of the disc, making bending more difficult.

Questions & Answers

What is red blood cell
HANNAH Reply
A type of blood cell that is made in the bone marrow and found in the blood. Red blood cells contain a protein called hemoglobin, which carries oxygen from the lungs to all parts of the body. Checking the number of red blood cells in the blood is usually part of a complete blood cell (CBC) test. It
Noor
red blood cell are the most numerous blood cells.they comprise about 99% of all blood cells red blood cells are non nucleated it has red colour due to present to hemoglobin.
Vineeta
Thanks for the answers
HANNAH
how will you promote quality of life in ptb patient using the 14 basic needs and 21 nursing problems?
rOx Reply
coronary circulation ?
Juri Reply
Coronary circulation is the circulation of blood in the blood vessels that supply the heart muscle (myocardium). Coronary arteries supply oxygenated blood to the heart muscle, and cardiac veins drain away the blood once it has been deoxygenated. Because the rest of the body.
Riyaz
coronary circulation ,is flow of blood that supplies the heart tissue itself is the coronary circulation. the functional blood supply of the heart,is the shortest circulation in tha body.
Vineeta
what about the easy way to understand action potential
Bright
event of cardiac cycle
Juri Reply
hii
Chandan
whatisanatom
kaso Reply
anatomy is the scientific way of studying the body structure.
cynthia
the branch of science concerned with the bodily structure of humans, animals, and other living organisms, especially as revealed by dissection and the separation of parts.
Noor
what is means by LAPE and HAPE
Noor
guys i've question what occur when homeostasis balance mechanisms lost
cris Reply
Bladder is blank to the small intestine, what is the right directional term for that?
Julaika Reply
When peristaltic movement is correct.
Farid
what tissue that support body organ?
Sabrina Reply
the skeleton
veronica
Skeleton
GEBAH
skeleton
Juwita
skeleton
Farid
skeleton
Priya
skeleton
Emmanuel
skeleton
Noor
skeleton
BILAL
skeleton
hanuman
how many bones are there in the body
hanuman Reply
go uuu
Prasad
206
Prasad
206
Nelago
206
Esmeralda
206
Joey
baby me 360. and human body 206.found bones.....
Sneha
what is a tissue in Anatomy and physiology
Nelago
206 bones
Juwita
what is an example of a molecule that can directly pass through the phospholipid bilayer of the plasma membrane?
Kathy
206
Johara
how many bones are there in the hand and wrist
hanuman
200 tissue
hanuman
answer 206 bones
GEBAH
axial 80 appendicular 126 total bone is 206
Vineeta
wrist bone 8
Vineeta
baby bone 270 he is correct answer
hanuman
Jo carpus wrist bone h
Vineeta
206
Musonda
206 bones in human body.
Farid
What is Heart attack?
Farid
206
Priti
206 all
Sa
All 206
Sa
A heart attack happens when the flow of oxygen-rich blood to a section of heart muscle suddenly becomes blocked and the heart can't get oxygen. If blood flow isn't restored quickly, the section of heart muscle begins to die. Heart attack treatment works best when it's given right after symptoms occu
Riyaz
how can l understand Anatomy quickly?
Agness Reply
you can't!!!! Anatomy is easy but the physiology takes time to understand. Anatomy is simply systems and organs but you must take time to learn physiology to understand how the anatomy works
Rachael
alright.. so how can l at least memorize the information about physiology?
Agness
what name is given to the fluid that is drawn from the villi to the lymphatic vessels
margaret Reply
I think venous
Noor
lymph
Rachael
I also think it's lymph
Akhi
me too I think lymph
Esmeralda
ans Rhythmic contraction
GEBAH
what are the ten (10) rights for drug administration
GEBAH
importance of muscle in the anatomical structures.
Akomeng Reply
it permits the constant level of movement,and gives structure and shape to the body
Priya
what is assimilation
Asiimwe Reply
cellular level organism level chemical level organ system level tissue level organ level
Aleah Reply
, the current topic
Hilya
cellular level
Priya
tissue level
Priya
organ level
Priya
organ systems level
Priya
organism level
Priya
what is anatomy?
Aleah Reply
anatomy is the study of internal parts of body by disecting it.
Shweta
The study of the internal body parts and it's organs are referred as Anatomy.
Adarsh

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Source:  OpenStax, Anatomy & Physiology. OpenStax CNX. Feb 04, 2016 Download for free at http://legacy.cnx.org/content/col11496/1.8
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