Source: Chapter 7 Bones Worksheet, University of Florida A&P
Difficulty: Introductory–Intermediate | Prerequisites: Basic body orientation terms (anterior, posterior, superior, inferior, medial, lateral)
Tags: axial skeleton, skull, cranium, vertebral column, vertebrae, cervical, thoracic, lumbar, sacrum, coccyx, ribs, sternum, thoracic cage, skeletal system, bone identification, anatomy and physiology, Chapter 7
The skeletal system has two major divisions: the axial skeleton and the appendicular skeleton. This set of notes covers the axial skeleton, which forms the central longitudinal axis of the body. It includes the skull, the vertebral column, and the thoracic cage (ribs and sternum). If you are coming into this cold, know that the axial skeleton is essentially the "core frame" of the body, everything that is not a limb or limb girdle. Mastering these bones is foundational for every subsequent chapter on joints, muscles, and the nervous system.
The axial skeleton consists of 80 bones forming the body's central axis: the skull (cranial and facial bones), the vertebral column (cervical, thoracic, lumbar vertebrae plus the sacrum and coccyx), and the thoracic cage (ribs and sternum). Knowing where each bone sits, from both the anterior and posterior views, is the core task of this chapter.
Axial skeleton
The 80 bones forming the longitudinal axis of the body: skull, vertebral column, and thoracic cage. Think of it as the central scaffolding that protects the brain, spinal cord, and thoracic organs.
Orbital cavity
The bony socket that houses and protects the eye. In simple terms, it is the eye socket, formed by contributions from several skull bones.
Nasal cavity
The air-filled space behind the nose, bounded by bone and cartilage. It warms, humidifies, and filters inhaled air before it reaches the lungs.
Cranium
The portion of the skull that encloses and protects the brain, composed of eight flat bones fused at sutures. Think of it as the helmet part of the skull.
Vertebral column (spine)
A flexible, curved column of 26 bones (in the adult) that protects the spinal cord and supports the head and trunk. Often called the spine or backbone.
Cervical vertebrae
The seven vertebrae of the neck region (C1–C7), the most superior segment of the vertebral column. These are the smallest, most mobile vertebrae.
Thoracic vertebrae
The twelve vertebrae of the mid-back (T1–T12), each articulating with one or more pairs of ribs. In simple terms, these are the vertebrae that connect to your ribs.
Lumbar vertebrae
The five large vertebrae of the lower back (L1–L5), bearing the most body weight of any vertebral segment. These are the thickest, sturdiest vertebrae.
Sacrum
A triangular bone formed by the fusion of five sacral vertebrae, wedged between the two hip bones. It transmits the weight of the upper body to the pelvis.
Coccyx (tailbone)
A small, triangular bone at the inferior end of the vertebral column, formed from 3–5 fused vertebrae. In simple terms, this is the vestigial tailbone.
Sternum (breastbone)
The flat bone at the anterior midline of the thorax, composed of three parts: the manubrium (superior), the body (middle), and the xiphoid process (inferior). It anchors the ribs at the front of the chest.
Ribs
Twelve pairs of curved, flat bones forming the lateral walls of the thoracic cage. The first seven pairs are "true ribs" (attached directly to the sternum via costal cartilage), pairs 8–10 are "false ribs" (indirect sternal attachment), and pairs 11–12 are "floating ribs" (no sternal attachment at all).
Thoracic cage (rib cage)
The bony enclosure formed by the thoracic vertebrae posteriorly, the ribs laterally, and the sternum anteriorly. It protects the heart and lungs and assists with breathing mechanics.
The orbital cavities are the paired bony sockets visible on the anterior skull; each is formed by parts of seven different bones.
The nasal cavity sits between and below the orbits. It is divided by the nasal septum.
On an anterior skeleton diagram, the skull sits atop the cervical vertebrae. The lower jaw (mandible) is the only movable bone of the skull.
Cervical region (C1–C7): located in the neck. C1 (atlas) supports the skull; C2 (axis) allows head rotation. These are visible from both the anterior and posterior views at the very top of the vertebral column.
Thoracic region (T1–T12): located in the mid-back, posterior to the sternum and ribs. Each thoracic vertebra has facets for rib articulation.
Lumbar region (L1–L5): located in the lower back. These are the largest vertebral bodies because they bear the greatest load.
Sacrum: inferior to L5, wedged between the hip bones.
Coccyx: the terminal segment, inferior to the sacrum.
The vertebral column is labelled as a whole structure on the anterior diagram and can also be seen running the full length of the posterior view.
The sternum is the midline bone on the anterior view, sitting between the clavicles superiorly and extending down the front of the chest.
The ribs curve laterally and posteriorly from the sternum, attaching to the thoracic vertebrae at the back. On the anterior diagram, the ribs are labelled on the left side of the body.
From the posterior view, the ribs are visible wrapping around from the vertebral column.
From the anterior view, you can directly see the orbital cavities, nasal cavity, sternum, and the full front of the rib cage.
From the posterior view, the vertebral column is fully exposed. You can see the spinous processes of each vertebra, the posterior surfaces of the ribs, and the scapulae (covered in the appendicular notes).
A common exam task is being given an unlabelled diagram from one view and needing to identify structures. Practise both views.
No mathematical formulas for this section. The key diagram is the full anterior and posterior skeleton labelling exercise from your worksheet. Practise labelling from memory on a blank diagram.
Vertebral count to memorise: 7 cervical, 12 thoracic, 5 lumbar, 1 sacrum (5 fused), 1 coccyx (3–5 fused).
A useful mnemonic for the vertebral counts: "Breakfast at 7, lunch at 12, dinner at 5" (cervical, thoracic, lumbar).
The cervical vertebrae are the reason whiplash injuries from car accidents are so dangerous: the neck is the most mobile and least protected segment of the spine. Understanding rib anatomy matters in clinical settings because rib fractures can puncture the lungs (pneumothorax), so knowing which ribs are where is essential for emergency assessment.
Students often confuse the sacrum and the coccyx. The sacrum is the larger, triangular, superior bone; the coccyx is the small terminal piece below it.
The terms "true ribs," "false ribs," and "floating ribs" do not describe different types of bone. All 24 ribs are structurally similar. The labels refer only to how (or whether) each pair connects to the sternum.
Students sometimes think the vertebral column is a single rigid bone. It is a flexible chain of 26 individual bones (plus intervertebral discs), which is why you can bend and twist.
The sternum is often drawn or imagined as a single flat slab, but it has three distinct parts (manubrium, body, xiphoid process) that examiners like to test.
⚠️ Be able to label every axial bone from both the anterior and posterior views without a word bank. Labelling exercises are a staple of practical exams.
⚠️ Know the vertebral formula: 7C, 12T, 5L, sacrum, coccyx. This comes up in multiple-choice questions constantly.
⚠️ Distinguish the three rib categories (true, false, floating) and know which rib pairs belong to each.
⚠️ The sternum's three parts (manubrium, body, xiphoid process) are frequently tested, especially the xiphoid process, which is a landmark for CPR hand placement.
True or false: The axial skeleton includes the bones of the arms and legs. ___
How many cervical vertebrae are there? ___
Fill in the blank: Ribs 11 and 12 are called ___ ribs because they have no attachment to the sternum.
True or false: The coccyx is superior to the sacrum. ___
The three parts of the sternum, from superior to inferior, are: ___, ___, ___.
Answers: 1. False (those are appendicular). 2. Seven. 3. Floating. 4. False (the coccyx is inferior). 5. Manubrium, body, xiphoid process.
Q: Name the five regions of the vertebral column from superior to inferior.
A: Cervical (7), thoracic (12), lumbar (5), sacral (sacrum, 5 fused), coccygeal (coccyx, 3–5 fused).
Q: Which bones form the thoracic cage?
A: The twelve pairs of ribs, the thoracic vertebrae (posteriorly), and the sternum (anteriorly).
Q: A patient fractures rib 11. Would this affect any costal cartilage connection to the sternum?
A: No. Ribs 11 and 12 are floating ribs with no sternal attachment at all, so the fracture would not involve a sternum connection.
Q: On an anterior view of the skeleton, where would you find the lumbar vertebrae relative to the ribs?
A: Inferior to the ribs. The lumbar vertebrae sit below the thoracic cage, in the lower back region.
Q: What is the clinical significance of the xiphoid process?
A: It serves as a landmark for CPR hand placement (hands go on the body of the sternum, above the xiphoid). Applying pressure directly to the xiphoid process can fracture it and damage underlying organs.
This material connects directly to Chapter 8 (joints and articulations), because every point where two bones meet is a joint, and axial joints (e.g., intervertebral joints, costovertebral joints) have unique movement ranges. It also underpins the study of axial muscles (deep back muscles, intercostals, abdominals), which attach to and move these bones. Understanding the vertebral column is essential for neuroscience topics as well, since the spinal cord runs through the vertebral foramen of each vertebra.
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