Skeletal muscles are a part of the muscular system. They are attached to the bones by tendons. Each of these muscles is surrounded by the epimysium, which is a sheath of connective tissue. Surrounding the epimysium and separating muscles from each other and from the...
The muscles of the face are the only muscle group in the human body that insert directly into the skin. They originate from bone or fascia and sit in the subcutaneous tissue. When these muscles contract, they pull on the skin resulting in facial expressions...
The muscles of the human body can be categorized into two groups: axial and appendicular muscles. Axial muscles are attached to the axial skeleton, which includes the bones located in the head, neck, and trunk. The function of the axial muscles is to support and...
The carotid sheath contains a few different structures. It contains the common carotid artery, the vagus nerve, the internal jugular vein, parts of the external and internal carotid arteries, the vagus nerve, portions of other nerves, and cervical lymph nodes. The common carotid and its...
The ear is the organ that enables hearing and balance. It can be divided into three parts: The outer ear The middle ear The inner ear The auricle or pinna and the ear canal belong to the outer ear. This is the only visible part...
The retina contains special neurons that are able to detect light and convert it into electrical signals that can be sent to the brain. These neurons are called photoreceptors. There are two types of photoreceptor cells: Rods Cones Rods are photoreceptor cells that are very...