Human back

Key takeaways

Human back belongs to biology; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Human back to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Human back from memory before moving on to harder problems.

Reference excerpt

The human back, also called the dorsum (pl.: dorsa), is the large posterior area of the human body, rising from the top of the buttocks to the back of the neck. It is the surface of the body opposite from the chest and the abdomen. The vertebral column runs the length of the back and creates a central area of recession. The breadth of the back is created by the shoulders at the top and the pelvis at the bottom. Back pain is a common medical condition, generally benign in origin.

Structure The central feature of the human back is the vertebral column, specifically the length from the top of the thoracic vertebrae to the bottom of the lumbar vertebrae, which houses the spinal cord in its spinal canal, and which generally has some curvature that gives shape to the back. The ribcage extends from the spine at the top of the back (with the top of the ribcage corresponding to the T1 vertebra), more than halfway down the length of the back, leaving an area with less protection between the bottom of the ribcage and the hips. The width of the back at the top is defined by the scapula, the broad, flat bones of the shoulders.

Muscles

The muscles of the back can be divided into three distinct groups; a superficial group, an intermediate group and a deep group.

Superficial group The superficial group, also known as the appendicular group, is primarily associated with movement of the appendicular skeleton. It is composed of trapezius, latissimus dorsi, rhomboid major, rhomboid minor and levator scapulae. It is innervated by anterior rami of spinal nerves, reflecting its embryological origin outside the back.

Intermediate group The intermediate group is also known as respiratory group as it may serve a respiratory function. It is composed of serratus posterior superior and serratus posterior inferior. Like the superficial group, it is innervated by anterior rami of spinal nerves.

Deep group The deep group, also known as the intrinsic group due to its embryological origin in the back, can be further subdivided into four groups:

Spinotransversales – composed of splenius capitis and splenius cervicis. Erector spinae – composed of iliocostalis, longissismus and spinalis Transversospinales – composed of semispinalis, multifidus and rotatores Segmental muscles – composed of levatores costarum, interspinales and intertransversarii The deep group is innervated by the posterior rami of spinal nerves.

Organs near the back The lungs are within the ribcage, and extend to the back of the ribcage making it possible for them to be listened into through the back. The kidneys are situated beneath the muscles in the area below the end of the ribcage, loosely connected to the peritoneum. A strike to the lower back can damage the kidneys of the person being hit.

Surface of the back The skin of the human back is thicker and has fewer nerve endings than the skin on any other part of the torso. With some notable exceptions (see, e.g., George "the Animal" Steele), it tends to have less hair than the chest on men. The upper-middle back is also the one area of the body which a typical human under normal conditions might be unable to physically touch. The skin of the back is innervated by the dorsal cutaneous branches, as well as the lateral abdominal cutaneous branches of intercostal nerves.

Movement The intricate anatomy of the back provides support for the head and trunk of the body, strength in the trunk of the body, as well as a great deal of flexibility and movement. The upper back has the most structural support, with the ribs attached firmly to each level of the thoracic spine and very limited movement. The lower back (lumbar vertebrae) allows for flexibility and movement in back bending (extension) and forward bending (flexion). It does not permit twisting.

Clinical significance

Back pain

The back comprises interconnecting nerves, bones, muscles, ligaments, and tendons, all of which can be a source of pain. Back pain is the second most common type of pain in adults (the most common being headaches). By far the most common cause of back pain is muscle strain. The back muscles can usually heal themselves within a couple of weeks, but the pain can be intense and debilitating. Other common sources of back pain include disc problems, such as degenerative disc disease or a lumbar disc herniation, many types of fractures, such as spondylolisthesis or an osteoporotic fracture, or osteoarthritis.

Society and culture

… excerpt ends here. Continue reading the full article.

Illustrations

Worked examples

Example 1 — a first encounter with Human back

Start with the simplest possible case. Write down what Human back claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In biology, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Human back before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Human back ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Human back

In research: Human back appears in biology research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Human back in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Human back is common in secondary-school and first-year university syllabi. It links to neighbouring topics Human anatomy, Human back, so understanding it makes those chapters shorter.
In everyday life: Look for Human back outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

How to study Human back in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Human back means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Human back out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Human back in simple terms?

The human back, also called the dorsum (pl.: dorsa), is the large posterior area of the human body, rising from the top of the buttocks to the back of the neck. It is the surface of the body opposite from the chest and the abdomen.

Why does Human back matter?

Because it connects several biology ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Human back?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Human back.