Understanding mammal anatomy is essential for fast and accurate field sketching. You do not need to memorize every muscle in the book but there are 6 muscles that a mammal artist should have under their belt. These make distinct lumps and contours on the body. On long-haired mammals such as a bear, you do not need to be that exact. The fur hides a lot of detail. Still, these six muscles will come into play again and again as you draw other mammals. Time spent learning them now will pay off immeasurably as you continue to draw.
Muscles originate across a broad area of a bone or the skeleton and insert into a small point on another bone, crossing over at least one joint. As the muscle contracts, it opens or closes the joint. Muscles tend to be broader where they originate close to the core of the body and have the smaller insertion point out the limbs.
Print out the mammal anatomy worksheet and follow the In the step by step guide below, adding one muscle at a time. Then envision how these muscles show through skin and fur. This will help you memorize the shapes and locations of the muscles better than just reading this post. Click on the first image to initiate a sideshow with step by step details.
The bear has a plantigrade stance with the entire sole of the foot on the ground. The limbs are relatively short.
The gastrocnemius or calf muscle originates at the back of the femur and inserts into the tip of the heel bone. The space between the tendon near the heel and the leg bone makes a prominent divot in the back of the leg and can be seen in many mammals.
The crural triceps originate on the pelvis and femur and insert into the top of the knee cap. This is the equivalent of the quadriceps in the human. This bulky muscle makes a prominent bump at the front of the thigh.
The biceps femoris is an exception to the generality that muscles become smaller as they move away from the core of the body. This muscle originates from the end of the pelvis and fans out in a big triangle to the base of the knee and across the gastrocnemius. The rear edge of this muscle makes a ridge along the back of the leg in short haired animals.
The triceps brachialis is the large muscle at the back of the upper arm. It originates along the base of the shoulder blade and the humerus and inserts into the tip of the ulna at the elbow.
The extensor carpi radialis is a ropey muscle in the front of the forearm. It originates near the base of the humerus and inserts into the wrist. This muscle gives some thickness to the forearm but not as much as you see in the upper arm.
The brachiocephalicus is a thick muscle that sits on either side of the neck and turns the head side to side. The lower edge of this muscle often makes a prominent grove called the jugular grove. The muscle originates at the back of the skull and inserts into the humerus (upper arm).