In summary, the muscles that move the forearm can be categorized based on general action. The biceps brachii is a forearm flexor along with the brachialis and the brachioradialis. The triceps brachii extends the forearm. The pronator teres muscle pronates the forearm, while the supinator supinates the forearm.
Push-ups require extension of the forearm at the elbow, thus utilizing this triceps brachii muscle. Now, let's move on to our pronators and supinators. Pronation and supination refer to rotation of the forearm at the elbow.
The brachioradialis is one of my favorite forearm flexor muscles because it's easy to remember based on its name. You see, the name helps us to remember where it's attached. It originates from the humerus and inserts on the radius of the forearm. The term brachium refers to that part of the upper appendage containing the humerus.
Most of us can recognize the biceps brachii as a forearm flexor muscle - and it certainly is. This is the muscle that bulges when we show our guns. When I worked out in school, we always did curls for the girls, as we were trying to get big biceps brachii, or guns, so to speak.
As the name suggests, this muscle has two heads - that is, two points of origin. Both the long head and the short head of the biceps brachii origina te from the scapula and insert on the forearm. In addition to flexing the forearm, the biceps brachii helps to stabilize the shoulder joint.
Most of the muscles that move the forearm originate from the humerus and insert on the forearm itself. However, the biceps brachii and triceps brachii are two noteworthy exceptions, as they originate from the scapula and insert on the forearm. This lesson will identify and describe the various muscles that move the forearm. We will discuss them in groups based on their general action.
Using anatomical terminology, the arm specifically refers to the upper appendage from the shoulder down to the elbow, and the forearm specifically refers to the lower appendage from the elbow down to the wrist. Muscles in the shoulder are responsible for moving the arm, and muscles in the arm are responsible for moving the forearm.
Muscles that help push are the following: pectorals, triceps, quadriceps, and calves. Yes, you have noticed well. Shoulders are not classified in this category despite the fact that you push the weight away from your body when you do barbell or shoulder presses. Pushing exercises include push-ups, bench presses, back squats, triceps overhead presses, forward lunges, calf raises, and countless other exercises.
Swinging muscles. These muscles assist and support in moving your torso through various planes of motion. For example, bending your body from side to side, twisting right and left, lowering and rising your torso, etc.
Your quads – the muscles that rest along the fronts of your thighs – divide into four separate heads: the vastus intermedius, the rectus femoris, the vastus lateralis, and the vastus medialis . The vastus intermedius attaches to and covers much of the front and sides of your femur (your thighbone) but is not visible, as it lies below the rectus femoris. The rectus femoris starts at your pelvis and runs down your thigh in front of the vastus intermedius. The vastus lateralis and medialis begin at the back of your femur laterally and medially, respectively. All four quadricep muscles run down your thigh and converge at the patellar tendon, which attaches along the upper part of your tibia (shinbone).
HOW THEY WORK: Together, both muscles are responsible for moving your upper arms toward the center of your body and assist with drawing your shoulders forward. Whenever you either push a weight above your chest or push your body away from a stationary object (like the floor, when performing a pushup), your pectorals shorten in order to pull your arms across your chest and bring them together.
HOW THEY WORK: All three heads work together to extend your elbows. This is what you’re doing every time you straighten your arm from a bent position. This happens whenever you push a weight over your head or above your chest, for example. However, your triceps brachii also help out with other jobs. Foe example, they are stabilizing your shoulder joints during certain pushing movements and aiding your upper back muscles with arm adduction (which happens when you bring your arms down and back toward your body).
HOW THEY WORK: The gastrocnemius’s job is to flex your foot, which is what you do whenever you elevate your heels. The soleus does the exact same thing, but only when your knees are bent.
HOW THEY WORK: Your quadriceps are mainly responsible for extending your knees (straightening your legs). However, they also help to support and stabilize your knee joints, particularly the inner and outer sides. Because many of the pushing exercises that target your quadriceps also involve your lower legs. your quads often work in unison with your calves.
Triceps brachii. Wrist flexion. Bend your palm toward your forearm. Wrist flexors. Wrist extension. Bend the back of your hand toward your forearm. Wrist extensors. A helpful way to learn anatomy is to move and mimic the actions for the muscles you are learning that week.
This action at the shoulder can occur when your arm is in different positions (flexion, abduction, etc.). Infraspinatus and teres minor. Horizontal abduction. For the start postion, lift your arms in front of you. The action occurs as you then move your arms out to the side.
The two main actions of the wrist are flexion and extension. A helpful way to learn anatomy is to move and mimic the actions for the muscles you are learning that week. Look at the picture of the muscle, find it on your body, and picture how it is contracting as it produces its associated movement or movements.
The glenohumeral joint—commonly referred to as the shoulder joint—consists of the attachment of the humerus bone to the scapula. Many actions occur at this ball-and-socket joint. Action of the Shoulder. What the Action Looks Like (Try It Yourself!)
Return (lower) your arms from shoulder flexion or lift your arms behind you. Latissimus dorsi, teres major (“little lat”) Internal shoulder rotation. From the anatomical position, rotate your arm so that the elbow faces forward. This action at the shoulder can occur when your arm is in different positions (flexion, abduction, etc.).
External shoulder rotation. From a position of internal shoulder rotation, rotate your arm so that the elbow faces backward. Also, anatomical position requires the shoulders to be in external rotation.
As a fitness professional and an exam candidate, there is no way of getting around the fact that you need to know your anatomy! Understanding how the body moves and creates movement with the muscles is a huge part of the job. In an earlier blog, we looked at how to study anatomy. We then started breaking down each body part, with the last blog looking at the muscles that move the scapulae.
Muscles acting on the arm insert at the humerus, the long upper arm bone, from the shoulder or humeroscapular joint. Pectoralis major and latissimus dorsi are axial muscles that play primary roles in attaching the arm to the trunk. Pectoralis major is a large, fleshy muscle that runs across the upper chest from the sternum, clavicle, and upper costal cartilages. It assists in throwing, climbing, and pushing. The latissimus dorsi extends across the back from the lower vertebrae and ribs. It controls downward stroking movements as in swimming or hammering. The two muscles work as antagonists: pectoralis major flexes the shoulder forward and latissimus dorsi flexes it backward. The other seven muscles inserting at the humerus originate at the scapula. Most are innervated by the suprascapular nerve. The thick deltoid is the prime mover when the arm is abducted, or pulled away from the body. The deltoid is like a cap of muscle over the shoulder, and it flexes, rotates, and extends the shoulder by moving the humerus. However, the deltoid works as an antagonist to the pectoralis major and latissimus dorsi when adducting the arm (moving the arm toward the body). An antagonist muscle is a muscle that works by opposing the movement of the prime mover, slowing it down. An abductor is any muscle whose contraction moves a body part, such as a limb, away from the body's midline or away from another body part. The teres major and coracobrachialis muscles, as well as the pectoralis major and latissimus dorsi, adduct the humerus. An adductor is any muscle whose contraction moves a body part, such as a limb, toward the body's midline or toward another body part.
Hand motions are controlled by extrinsic muscles in the forearm connected to the hand by tendons and by muscles intrinsic to, or inside, the hand. The extrinsic muscles also act on the wrist. Muscles in the forearm are divided by connective tissue into anterior and posterior groups. Anterior group muscles are innervated by the median and ulnar nerves. The radial nerve innervates muscles in the forearm's posterior group. Wrist flexion is achieved by three anterior group muscles, the flexor carpi radialis, flexor carpi ulnaris, and the flexor digitorum superficialis. These each originate fully or in part at the humerus. The flexor carpi radialis inserts at the hand's second and third metacarpal bones and the flexor carpi ulnaris at the wrist bone called the pisiform. The flexor digitorum superficialis inserts at the middle phalange, or finger bone. Wrist extension is accomplished by posterior group muscles: primarily the extensor digitorum, plus the extensor carpi radialis longus, the extensor carpi radialis brevis, and the extensor carpi ulnaris. All originate at the humerus. The extensor digitorum inserts at bases of fingers 2 to 5; the other three insert at the bases of specific metacarpal bones 2 to 5. Wrist abduction is determined by the flexor carpi radialis, the extensor carpi radialis longus, the extensor carpi radialis brevis, and the abductor pollicis longus. The abductor pollicis longus is a posterior group muscle attached from the posterior ulna and radius in the forearm to the base of the first metacarpal. Wrist adduction is accomplished by two anterior forearm muscles, the flexor carpi ulnaris and the extensor carpi ulnaris.
Intrinsic hand muscles allow for delicate and precise finger movements. These muscles are divided into three groups. The hypothenar group (opponens digiti minimi, flexor digiti minimi brevis, abductor digiti minimi) lies at the base of the little finger, the fleshy thenar group (opponens pollicis, adductor pollicis, flexor pollicis brevis, abductor pollicis brevis) lies at the base of the thumb, and the midpalmar group (interosseous and lumbrical muscles) is located between the two. Thumb opposition is achieved by the opponens pollicis muscle. The adductor pollicis adducts the thumb, pulling it toward the other fingers. The flexor pollicis brevis flexes the thumb, while the abductor pollicis brevis abducts it. In the hypothenar group, the opponens digiti minimi pulls the little finger forward and rotates it to oppose the thumb. The abductor digiti minimi abducts the little finger, pulling it away from the other fingers. The flexor digiti minimi flexes the little finger at the metacarpophalangeal joint, which is the knuckle joint just below the base of the little finger. Eleven midpalmar group muscles are further divided by function into three subgroups. Four dorsal interosseous muscles attach to the metacarpal bones and abduct or spread the fingers. Three palmar interosseous muscles arising from the metacarpal bones adduct the fingers (move them together). Four lumbrical muscles flex the metacarpophalangeal joints—the proximal knuckles—and extend the distal knuckles, the interphalangeal joints.
In the hand, finger flexion or bending is accomplished by three anterior forearm muscles: the flexor digitorum superficialis, which also flexes the wrist, the flexor digitorum profundus, and the flexor pollicis longus. The flexor digitorum profundus originates at the ulna and inserts at the distal finger bones of digits 2 to 5. The flexor pollicis longus attaches from the radius to the distal portion of the thumb. Four posterior forearm muscles control finger extension, including the extensor digitorum, which also extends the wrist. The extensor pollicis longus originates at the ulna and inserts at the distal thumb phalanx. The extensor pollicis brevis attaches from the radius to the thumb's proximal phalanx. The extensor indicis originates at the ulna and inserts at the second digit.
Muscles acting on the pectoral girdle direct all movements of the scapula (shoulder) that enable motions of the upper limbs. The pectoralis major aids in pushing or throwing activities; the latissimus dorsi allows for downward strokes.
The biceps brachii, brachialis, and brachioradialis muscles flex the forearm. The biceps brachii is a prominent two-headed muscle visible on the front of the upper arm. Its heads have separate points of origin, the upper glenoid cavity and the scapula's coracoid process. It inserts at a tuberosity of the forearm's radius bone. The deeper brachialis muscle originates at the humerus and inserts at the forearm's ulna bone. The brachioradialis bulges in the forearm, attaching from the humerus to the styloid process of the radius. The triceps brachii and anconeus muscles extend the forearm. The triceps brachii originates at three points, one at the scapula and two at different spots of the humerus. It inserts at the ulna's olecranon process. The anconeus is in the forearm, from the lateral epicondyle of the humerus to the posterior ulna.
The biceps brachii, brachialis, and brachioradialis muscles flex the forearm. The triceps brachii and anconeus muscles provide extension. Supinator and pronator muscles permit conversion from a supine (palm-up) to a prone (palm-down) position.