The C5, C6, and C7 vertebrae sit in the lower portion of your cervical spine, roughly between the base of your throat and the bony bump you can feel at the back of your neck where it meets your upper back. C5 is at about the level of your Adam’s apple (or the equivalent spot in women), C6 sits just below it near the cricoid cartilage (the ring of cartilage you can feel at the bottom of the front of your throat), and C7 is the lowest cervical vertebra, often identifiable as the most prominent bony knob when you tilt your head forward. These three vertebrae form the workhorse section of the neck, bearing more mechanical load and hosting more clinically significant anatomy than their upper cervical neighbors.
How to Find Them on Your Own Body
The easiest starting point is C7. Tilt your chin down toward your chest and run your fingers along the back of your neck. The bump that sticks out most at the base of the neck is commonly called the vertebra prominens, and textbooks have long taught that it corresponds to C7. In practice, that shortcut is less reliable than you might expect. A cadaveric study found that only about half of people actually have C7 as the most prominent spinous process. In men, C7 was the vertebra prominens roughly 69% of the time, but in women it was more often C6, at about 44%, with C7 the most prominent in only about 35% of females studied.
1PubMed Central. Variability in the projection level of the vertebra prominens: a cadaveric studyFrom the front of the neck, clinicians sometimes use the cricoid cartilage as a landmark for C6, since this cartilage ring sits at roughly the C5/C6 disc level. But even that landmark has limited accuracy. One study found the cricoid cartilage correctly predicted the C5/C6 disc space only about 43% of the time.
2PubMed Central. Reliability and Accuracy of Palpable Anterior Neck Landmarks for the Identification of Cervical Spinal LevelsThe takeaway is that surface landmarks give you a rough neighborhood, not a precise address. Surgeons doing procedures in this area rely on imaging, not finger-feel, to confirm which level they are working on.
What Makes Each Vertebra Distinct
All three share the basic cervical vertebra blueprint: a small, oval-shaped body, a triangular spinal canal, and short spinous processes compared to the thoracic and lumbar vertebrae below. But each has identifying features that matter both anatomically and clinically.
C5 is a relatively unremarkable middle cervical vertebra in terms of shape. It sits at a transitional zone where the cervical lordosis (the inward curve of the neck) begins to deepen. Its clinical significance comes less from its bone structure and more from the nerve root that exits alongside it and the disc space above and below it.
C6 is distinguished by a large anterior tubercle on its transverse process, sometimes called the carotid tubercle or Chassaignac’s tubercle. This bony bump sits close to the carotid artery and is a palpable landmark that surgeons use during anterior approaches to the cervical spine. C6 also plays a major vascular role: it is the level where the vertebral artery typically enters the chain of transverse foramina (the small holes on either side of each cervical vertebra) on its way up toward the brain. In a study of over 900 vertebral artery courses, the artery entered at C6 in about 93% of cases.
3PubMed Central. Variations in Entrance of Vertebral Artery in Korean Cervical Spine: MDCT-based AnalysisC7, the vertebra prominens, has the longest spinous process in the cervical spine and lacks the foramen transversarium that the vertebral artery passes through in C3 through C6 (or rather, when the foramen is present at C7, it usually transmits only a small accessory vein, not the main artery). C7 also serves as a transitional vertebra between the mobile cervical spine and the much stiffer thoracic spine, giving it a somewhat hybrid character in terms of loading and movement.
The Vertebral Artery and Why C6 Matters for Surgery
The vertebral arteries are two of the four major arteries supplying your brain. Each one typically enters the transverse foramen at C6 and then threads upward through C5, C4, C3, C2, and C1 before entering the skull. This means any surgery, injection, or trauma involving the lower cervical vertebrae puts the vertebral artery at potential risk.
While C6 is the entry point for the vast majority of people, anatomical variants exist. A large imaging study found abnormal vertebral artery entry in about 8% of specimens, with the artery entering at C5 in roughly 5%, C4 in about 2.5%, and occasionally at C3 or C7.
4Scientific Reports. Entrance and origin of the extracranial vertebral artery found on computed tomography angiographyThese variants are typically harmless on their own, but they can create dangerous surprises during cervical spine surgery if the surgeon is working at a level where the artery is not expected. This is one reason preoperative imaging is standard before any invasive procedure in the neck.
Which Nerves Exit at Each Level
The spinal cord runs through the spinal canal formed by all the cervical vertebrae. At each level, a pair of nerve roots branches off and exits through openings called neural foramina. In the cervical spine, the nerve root is numbered for the vertebra below it: the C5 nerve root exits between C4 and C5, C6 exits between C5 and C6, and C7 exits between C6 and C7.
Each nerve root serves specific muscles and skin areas, which is why a problem at one level produces a recognizable pattern of symptoms. Research comparing clinical exams, imaging, and electrical testing has mapped these relationships in detail. The C5 nerve root primarily supplies the deltoid (shoulder), the infraspinatus (a rotator cuff muscle), the biceps, and the brachioradialis (the forearm muscle you use to flex your elbow with your thumb pointing up). C6 shares some territory with C5 but is the main supply for certain wrist-extensor muscles and the pronator teres, which rotates your forearm. C7 drives the triceps and the muscle that flexes your wrist toward your palm.
5PubMed Central. Determining C5, C6 and C7 myotomes through comparative analyses of clinical, MRI and EMG findings in cervical radiculopathyIn practical terms, if you have a herniated disc at C5-C6 compressing the C6 nerve root, you might notice weakness when extending your wrist or a numb or tingling sensation along the thumb side of your forearm. A disc problem at C6-C7 compressing C7 tends to affect the triceps and can produce numbness along the middle finger.
Why Symptoms from C6 and C7 Problems Often Overlap
Despite the neat maps in textbooks, real-world nerve compression rarely produces a clean, textbook presentation. A study comparing patients with confirmed C6 versus C7 radiculopathy found that arm pain and sensory symptoms were diffuse in both groups and were not reliably different between the two levels. About 41% of patients reported some weakness, but the specific pattern of weakness had limited value for telling C6 and C7 problems apart based on symptoms alone.
6Spine. Comparison of Symptoms From C6 and C7 RadiculopathyThis overlap happens because nerve roots share territory more than the diagrams suggest, and because inflammation from a compressed nerve can irritate neighboring roots. It is also why imaging, and sometimes electrophysiological testing, is often needed to pin down the exact level. Reflex testing can help: studies have found that specialized reflex tests of the upper limb can localize the affected nerve root with sensitivity and specificity comparable to MRI.
7PubMed. Clinical utility of reflex studies in assessing cervical radiculopathyThe Biomechanical Burden on C5, C6, and C7
The lower cervical spine carries a disproportionate share of the neck’s mechanical work, which goes a long way toward explaining why disc herniations, arthritis, and degenerative changes are so common at these levels. During flexion (bending your head forward), the C5/C6 and C6/C7 segments contribute a much larger percentage of the total motion than the upper cervical levels. One study measured the segmental contributions and found that C6/C7 alone accounted for roughly 29% to 37% of total cervical flexion in the middle-to-final range of the movement, with C5/C6 contributing about 23% to 29%.
8Journal of Spinal Disorders & Techniques. Segmental Percentage Contributions of Cervical Spine During Different Motion Ranges of Flexion and ExtensionDuring extension (looking up), the burden shifts upward somewhat, but C5/C6 still contributes heavily, accounting for about 30% of the early phase of extension. This means that every time you look down at your phone or tilt your head back to look at the ceiling, C5-C6 and C6-C7 are doing a large chunk of the bending. Over years and decades, that repetitive mechanical stress explains why the C5-C6 disc is the single most common site for cervical disc herniation, followed closely by C6-C7.
Disc Degeneration and the Cascade Effect
When a disc degenerates at C5-C6, the consequences do not stay confined to that one level. A biomechanical modeling study showed that as the C5-C6 disc progressively degenerates, the range of motion at that segment decreases in all directions. At the same time, the pressure inside the neighboring healthy discs increases, and the forces on the facet joints (the small paired joints behind each disc) rise at both the degenerated level and the adjacent normal levels.
9PubMed. Biomechanical effect of C5-C6 intervertebral disc degeneration on the human lower cervical spine (C3-C7): a finite element studyThis cascade effect means that a stiff, worn-out disc at one level can accelerate wear at the levels above and below it. Clinicians sometimes call this “adjacent segment disease,” and it is a well-known concern after cervical fusion surgery. If the C5-C6 segment is surgically fused, the C4-C5 and C6-C7 discs have to pick up the slack, potentially speeding up their own degeneration.
Whiplash and the Lower Cervical Spine
Rear-end car collisions produce a characteristic injury pattern in the neck, and the C5-C7 region bears the brunt. During a whiplash event, the cervical spine goes through a distinctive two-phase motion. In the first phase, the lower cervical vertebrae snap into extension while the upper cervical spine is still in flexion, forming an S-shaped curve that is not part of any normal movement. In the second phase, the entire neck extends backward.
10Clinical Biomechanics. Mechanism of whiplash injuryThat initial S-shaped phase is where much of the damage occurs, and it concentrates at the bottom of the cervical spine. Simulation studies have shown that the capsular ligaments around the facet joints at C6-C7 experience the largest stretching during whiplash, with strains reaching nearly 40% during an 8-g impact. Those levels also see the greatest sliding at the facet joints.
11Spine. Facet Joint Kinematics and Injury Mechanisms During Simulated WhiplashThis concentrated strain at C6-C7 helps explain why chronic neck pain after a car accident so often localizes to the lower neck and why disc injuries from whiplash tend to involve the C5-C6 and C6-C7 levels specifically.
Forward Head Posture and Your Lower Cervical Spine
If you spend hours hunched over a screen, the lower cervical vertebrae pay a price. Forward head posture shifts the head’s center of gravity in front of the cervical spine, forcing C5, C6, and C7 into more flexion while the upper cervical segments compensate by extending to keep your eyes level with the horizon. A biomechanical analysis found that as forward head posture increases, the lower cervical segments flex more, the suboccipital muscles at the base of the skull shorten considerably, and the cervical extensor muscles along the back of the neck lengthen and work harder.
12PubMed. Cervical sagittal balance: a biomechanical perspective can help clinical practiceInterestingly, the same study noted that forward head posture actually increases the size of the lower cervical neural foramina, the openings where nerve roots exit. This may explain why some people with nerve compression symptoms unconsciously adopt a forward head posture: it opens up space around the compressed nerve and reduces their pain. It is a short-term gain, long-term loss situation, since chronic forward head posture overloads the muscles, ligaments, and discs of the lower cervical spine over time.
Cervical Ribs at C7
A small percentage of people are born with an extra rib growing from the transverse process of C7. These cervical ribs occur in roughly 0.5% to 2.5% of the population, depending on the study and the population examined.
13MOJ Anatomy & Physiology. Cervical rib and thoracic outlet syndromeMost cervical ribs are small and completely harmless, discovered incidentally on an X-ray taken for some other reason. But when a cervical rib is large enough, it can compress the nerves of the brachial plexus or the subclavian artery, producing a condition called thoracic outlet syndrome. Symptoms can include pain, tingling, or weakness in the hand and arm, and in rare cases, vascular complications like blood clots. Although cervical ribs most commonly arise at C7, cases have been documented at C6 and even as high as C4 or C5.
14Global Radiology CME. What is the significance of this anomaly?Up to about 10% of people with a cervical rib eventually develop symptoms, meaning the vast majority live their entire lives without knowing they have one.
Why Almost Every Mammal Has Exactly Seven Cervical Vertebrae
Humans are not unique in having seven cervical vertebrae. Giraffes, mice, whales, and nearly every other mammal share the same count, a consistency that has puzzled biologists for over a century. Whether the neck is two inches long or several feet, the number stays at seven. Only a handful of exceptions exist: sloths and manatees can have six, eight, or even nine cervical vertebrae.
15PubMed Central. Breaking the constraint on the number of cervical vertebrae in mammals: On homeotic transformations in lorises and pottosThe reason appears to be deeply rooted in how mammalian embryos develop. The genes that pattern the body plan during embryonic development, particularly the Hox genes, link cervical vertebra number to many other developmental programs. Changes to cervical count seem to come packaged with increased risk of birth defects and early childhood cancer. One influential hypothesis proposed that mutations changing the number of cervical vertebrae are associated with neural tube defects and a higher susceptibility to embryonal cancers, making natural selection ruthlessly conservative about this trait.
16PubMed. Why do almost all mammals have seven cervical vertebrae? Developmental constraints, Hox genes, and cancerThe evolutionary constraints on the lower cervical vertebrae appear to have developed later than those on the upper cervical spine. Research into neck modularity suggests that C5, C6, and C7 became increasingly specialized as distinct functional units over evolutionary time, with their shape variation becoming more constrained and their role in supporting the head and enabling movement becoming more defined.
17Journal of Mammalian Evolution. Evolution of the Mammalian Neck from Developmental, Morpho-Functional, and Paleontological PerspectivesCervical ribs, mentioned earlier, may actually represent a mild version of what happens when this evolutionary constraint weakens slightly. A cervical rib is essentially C7 starting to behave like a thoracic vertebra, an echo of the homeotic transformations that evolutionary pressure has otherwise been suppressing for hundreds of millions of years.
Surgical Approaches to C5, C6, and C7
When conservative treatment fails for disc herniations, bone spurs, or spinal cord compression in the lower cervical spine, surgery at C5-C7 is among the most frequently performed spinal procedures. The most common approach is anterior cervical discectomy and fusion, where the surgeon reaches the spine through the front of the neck, removes the damaged disc, and replaces it with a graft or cage to fuse the two vertebrae together. Multi-level procedures spanning C4 through C7 are not uncommon when degeneration affects multiple segments, with titanium plates used to stabilize the construct while the fusion heals.
18PubMed Central. Surgical anatomy of microsurgical 3-level anterior cervical discectomy and fusion C4-C7From the back of the neck, posterior approaches target the neural foramina to decompress pinched nerve roots. The anatomical relationship between the nerve roots and the bony landmarks at each level has been carefully mapped for these procedures: cadaveric studies have confirmed that the distance between key bony reference points and the nerve roots increases at lower cervical levels, which has practical implications for how precisely a surgeon must navigate when working at C5-C6 versus C7-T1.
19PubMed Central. The Anatomical Relationship Between the Cervical Nerve Roots, Intervertebral Discs and Bony Cervical Landmark for Posterior Endoscopic Cervical Foraminotomy and Discectomy: A Cadaveric StudyOne well-known surgical complication specific to this region is C5 palsy, a temporary weakness of the deltoid and biceps that can occur after decompression at C4-C5 or C5-C6. The C5 nerve root is shorter and more tethered than the roots below it, making it vulnerable to a traction injury when the spinal cord shifts backward after decompression. The condition usually improves over months, but it is a reminder that the anatomy of each level in this small stretch of spine has its own surgical personality.
The Micro-Architecture of Lower Cervical Bone
The internal structure of C5, C6, and C7 differs from both the upper cervical vertebrae and the thoracic vertebrae below. Micro-CT imaging of lower cervical specimens has revealed that the bone within the vertebral plates transitions from flat, sheet-like trabeculae near the outer cortical bone to rod-shaped trabeculae in the inner marrow space. Near the spinous processes, the trabecular bone is only one or two layers thick before giving way to the rod-shaped internal architecture.
20Nature. Exploring the micromorphological characteristics of adult lower cervical vertebrae based on micro-computed tomographyThis matters clinically because the thinness of the trabecular architecture in the spinous processes and pedicles helps explain why screw fixation in the cervical spine requires different techniques and hardware than fixation in the lumbar spine, where the bone is much denser and thicker. It also means that osteoporosis can affect the lower cervical vertebrae in ways that compromise surgical outcomes, since screws and plates need adequate bone quality to hold.