Anatomy Lesson: The Shoulders & Neck, Our Head’s Stability and Support
By Leslie LaPlace
We’ve come to the second-to-last installment of our Anatomy Lesson series. For our final articles I’m separating the upper body into two anatomical groups: the shoulder and neck areas, and the arms.
The shoulders and neck are areas of the body that support and control many key functions such as protecting the connection between our brain and body, and supporting a range of arm and head motions. One of the best ways to keep your neck and shoulder muscles healthy is to maintain good posture. You should also make a habit of breathing from the diaphragm and not the shoulders. In this video, I explain more about these best practices and offer simple exercises to help you keep your shoulders and neck strong and healthy.
Now, let’s take a look at the bones, joints and muscles that make up the shoulders and neck.
Basic Skeletal Structure of the Shoulders and Neck
The shoulder has the widest range of motion of any part of the body and is made up of a complex group of bones and joints.
The scapula is also called the shoulder blade. It’s a triangle-shaped flat bone that’s connected to the body by many muscles. It attaches the arm (from the humerus, which will be discussed in the next Anatomy Lesson) to the torso.
The clavicle is also called the collarbone. Like the scapula, it attaches the arm to the torso. It also helps to distribute force from the upper part of the arm to the rest of the skeleton.
Acromioclavicular joint.The acromion is a bony projection at the end of the scapula. The scapula and the clavicle meet to form the joint.
Glenohumeral joint.This is the ball and socket joint where the scapula and humerus (upper arm bone) meet.
The neck, also called the cervical spine, is composed of bones, nerves, muscles, ligaments and tendons. The cervical spine is delicate — it is home to the spinal cord, which sends messages from the brain and controls all aspects of the body. At the same time, it is incredibly flexible and strong, which allows the neck to move in all directions.
Cervical Spine. This is located between the skull and the thoracic vertebrae in the mid-back. It consists of seven vertebrae, numbered C1 through C7.
Hyoid Bone. The hyoid is located at the front of the neck, between your chin and thyroid cartilage. It’s key to allowing your tongue to move and to the function of swallowing.
Basic Muscles of the Shoulders and Neck
Your shoulder and neck muscles are skeletal muscles. Tendons attach them to bones. They’re voluntary muscles, which means you decide how and when to use them. Some other muscles in your body, such as those in your heart, are involuntary, which means they work on their own, without your direction. You don’t have to think about it for involuntary muscles to do their job.
Several muscles stabilize the three joints that make up the shoulder and give it motion. Your shoulder muscles enable you to perform a wide range of movements such as throwing a ball or reaching for an item. The ball-and-socket joint in your shoulder has more range of motion than any other joint in your body. Eight muscles in your shoulder support this joint, providing strength, shape and stability.
The eight muscles in your shoulder attach to the scapula, humerus and clavicle, forming the outer shape of the shoulder and underarm. These muscles help you perform a wide range of movements and protect and maintain the ball-and-socket or glenohumeral joint.
Rotator Cuff: Maybe the most important group of muscles in the shoulder, the rotator cuff is a collection of muscles – supraspinatus, infraspinatus, teres minor and subscapularis – and tendons that surround the shoulder in a cuff, giving it support and allowing a wide range of motion.
Deltoid: This is the largest of the shoulder muscles, and it is a large triangular muscle (hence the name, which comes from the similarly shaped Greek letter delta) that gives the shoulder its rounded shape. One important function of the deltoid is preventing joint dislocation when a person carries heavy objects, but it also moves the arm and shoulder joint simultaneously. It is comprised of three heads:
Anterior deltoid, which moves the arm forward and rotates the shoulder joint;
Lateral deltoid, which is in the middle of the shoulder and rotates the shoulder joint laterally (to the side), allowing you to lift your arm sideways to form a partial T. The shoulder joint moves down to accommodate as your arm moves out and up.
Posterior deltoid, which is located at the back of the shoulder, also rotates the joint laterally so the arm can move out and backward. When you move your arm backward, the shoulder joint will roll downward and inward.
Other muscles that aid in shoulder movement include:
Infraspinatus: A rotator cuff muscle that helps you raise and lower the upper arm
Pectoralis major: A large fan-shaped muscle connected to the sternum (breastbone) that stretches up from the armpit to the collarbone and down across the region of your lower chest
Pectoralis minor: A smaller pectoralis muscle that fans out from the upper ribs up to the shoulder
Teres major: A muscle that helps to rotate the upper arm
Latissimus dorsi: A flat rectangular back muscle that helps the arms rotate and move away from or closer to the body
Subscapularis: A large triangular-shaped muscle located near the humerus and collarbone that helps rotate the humerus
Supraspinatus: A small muscle located at the top of your shoulder that helps raise the arm away from the body
Rhomboids: Two rhomboid muscles (rhomboid minor and rhomboid major) that stretch from the top of your spine (at the base of your neck) to your scapula and help you lift your shoulder blade
Trapezius: A large triangular muscle at the back of your shoulder that helps you lift and lower your shoulder
These muscles are used for a wide range of motions and often bear heavy loads. As such, it’s common to experience shoulder muscle pain. The most common cause of shoulder pain is overexertion or injury to a muscle. Twisting, pulling or falling can cause injuries or overexertion. Deep muscle injuries can also happen from repetitive use, but it’s more common to experience pain and soreness from heavy lifting or overexertion. This pain usually subsides in a few days.
More than 20 neck muscles extend from the base of your skull and your jaw down to your shoulder blades and collarbone. These muscles support and stabilize your head, neck and upper spine. They also help you move your head in four different directions – side to side (rotation), ear to shoulder (lateral), chin to chest (flexion) and chin up (extension).
The neck muscles also serve these functions:
Keeping your upper ribs elevated so you can inhale.
Helping with swallowing, chewing and speaking.
Helping you make certain facial expressions.
There are three groups of neck muscles: anterior, posterior and lateral. I will keep the focus of this article on just a few of the major muscles from each of these groups:
Anterior (front) neck muscles begin at your jaw and extend to your collarbone. These muscles are responsible for jaw and mouth movements, moving your head, stabilizing the collarbone, helping to swallow and speak and breathing.
Sternocleidomastoid is a muscle that helps you move your head, extend your neck and control your temporomandibular joint (a joint in your jaw that connects your lower jaw to your skull). This muscle runs from just behind your ear to your collarbone and is one of the largest muscles in the neck.
Scalene muscles are three muscles on each side of your neck. They move your first two ribs up and down so you can inhale air when you breathe. They also help move the head and stabilize the cervical spine bones in your neck.
Posterior (back) neck muscles begin just beneath the base of your skull and extend down around your shoulder blades near the middle of your back. These muscles assist in moving your head in different directions.
Transversospinalis muscles are a group of five muscles that help you move your head forward and backward and tilt from side to side. They also help stabilize and move the whole spine.
Lateral (side) neck muscles also control head movements.
Rectus capitis anterior and rectus capitis lateralis control head movements from the base of your skull.
Longus capitis and longus colli allow you to twist your head from side to side and twist and tilt your cervical spine.
The neck and shoulders enable you to literally hold your head up high. Make sure you’re strengthening and supporting them through healthy practices and the strength exercises we shared at the start of this article!
Leslie LaPlace, Fitness Manager at Goodwin House Alexandria, is a self described recovering Software Development Project Manager. Leslie parlayed a lifelong love of and belief in the restorative power of exercise into a satisfying career working with adults ages 55 and older. She believes that staying active can help reduce aches and pains—It’s also a great anti-aging remedy. She has more than eight years’ experience working with seniors at Arlington County, The Jefferson, Goodwin House Bailey’s Crossroads and Goodwin House Alexandria. Leslie is a certified personal trainer and aquatic instructor who loves creating a positive and fun training experience. She believes that it’s never too late to improve your strength and balance!