The muscular system encompasses all the skeletal muscles in the body. These muscles are attached to the skeleton and are under voluntary control, meaning we can consciously control their movement.
Skeletal muscle, the most prominent type, is responsible for moving and stabilising the skeleton. It consists of elongated cells or fibres arranged parallel to each other. Remarkably, each cell has multiple nuclei and appears striped or striated under a microscope, earning it the name “striated muscle.” Each cell contains countless microscopic fibres, and the stripes are formed by two types of proteins that slide over each other, allowing the cell to contract.
In addition to skeletal muscle, there are two other muscle types: smooth muscle and cardiac muscle. These types are not under voluntary control and are not part of the muscular system.
Smooth muscle, also known as involuntary muscle, performs unconscious routine tasks in the body. These include activities like moving food through the digestive system, adjusting blood vessel diameter, and focusing the eyes. Smooth muscle cells are spindle-shaped, with a fatter middle and tapered ends, housing a nucleus in the center. They often form sheets and are stimulated by the autonomic nervous system and hormones.
Cardiac muscle is unique to the heart’s walls and consists of branching fibres forming a three-dimensional network. Under a microscope, cardiac muscle cells reveal a central nucleus and faint stripes or striations. These cells can contract spontaneously and rhythmically, and the heartbeat is coordinated by the sinoatrial node (natural pacemaker), with nerve and hormone influence modifying this rhythm.
The primary function of muscles is to enable movement in the dog’s body, either for the whole body or specific body parts. Muscles also play a crucial role in stabilising joints, preventing them from collapsing under a load. Smooth muscles help maintain bladder continence and facilitate the movement of food through the bowel. Additionally, muscles generate heat, particularly through shivering.
Voluntary muscles can contract and pull, but they lack the ability to push. As a result, they work in pairs to flex and extend. Extensor muscles straighten the limbs and attach to the bones, effectively acting as levers. On the other hand, flexor muscles bend the joints to lift the limb, and their counterpart, the extensor muscles, contract to lower the limb. The abductor muscles move the limbs away from the midline, while the adductor muscles draw the limbs toward the midline. These muscle actions coordinate complex movements and allow dogs to perform a wide range of activities with precision and agility.
A solid grasp of anatomy and physiology is crucial for hydrotherapists to provide optimal patient care and establish themselves as respected professionals within the multi-disciplinary team.
In hydrotherapy, patients are frequently referred with orthopaedic conditions, making it vital for hydrotherapists to understand the specific surgery or condition and its location within the body.
Knowing how the patient’s body will physiologically respond to hydrotherapy treatment is essential for delivering effective care.
Without the knowledge acquired in this chapter, hydrotherapists may face challenges in providing comprehensive and effective treatment to their patients.
Forelimb Muscles
The canine forelimb is composed of a complex network of muscles that work together to provide stability, strength, and movement to the front limbs. These muscles can be categorised based on their functions and locations. Here is an outline of the major muscle groups in the canine forelimb:
Shoulder Muscles
Supraspinatus: Located above the scapula spine, it assists in shoulder joint stability and abduction of the limb.
Infraspinatus: Found below the spine of the scapula, it aids in shoulder joint stability and lateral rotation of the limb.
Subscapularis: Situated beneath the scapula, it contributes to shoulder joint stability and medial rotation of the limb.
Teres Major and Teres Minor: These muscles are located on the side of the scapula and assist in shoulder joint stability and adduction of the limb.
Brachial Muscles
Biceps Brachii: Located on the front of the upper arm, it is responsible for elbow joint flexion and shoulder joint extension.
Brachialis: Situated deep to the biceps brachii, it aids in elbow joint flexion.
Brachioradialis: Found on the outer side of the forearm, it contributes to elbow joint flexion and stability.
Antebrachial Muscles
Extensor Carpi Radialis: Located on the top of the forearm, it aids in extending the carpal joint.
Flexor Carpi Radialis and Flexor Carpi Ulnaris: These muscles are positioned on the inner side of the forearm and assist in flexing the carpal joint.
Extensor Digitorum Communis: Situated on the top of the forearm, it helps extend the digits.
Flexor Digitorum Superficialis and Flexor Digitorum Profundus: These muscles are found on the inner side of the forearm and aid in flexing the digits.
Carpal and Digital Muscles
These muscles are smaller and are involved in the movement and stability of the carpal and digital (toe) joints.
Each of these muscle groups works in coordination with one another to allow dogs to perform various activities, including walking, running, jumping, and grasping objects with their front paws. Proper strength and flexibility in these muscles are essential for maintaining the overall health and mobility of the canine forelimb.
Hindlimb Muscles
The canine hindlimb is a powerful and complex system of muscles that play a vital role in providing support, stability, and propulsion during various activities. The muscles of the hindlimb can be categorised based on their functions and locations. Here is an outline of the major muscle groups in the canine hindlimb:
Hip Muscles
Gluteal Muscles: The gluteal muscles include the gluteus medius, gluteus minimus, and gluteus maximus. They are located on the rear of the pelvis and are responsible for hip joint extension, abduction, and stabilisation.
Deep Hip Muscles: These muscles lie beneath the gluteal muscles and aid in hip joint stabilisation and extension.
Thigh Muscles
Quadriceps Femoris: The quadriceps femoris is a group of four muscles, including the rectus femoris, vastus lateralis, vastus medialis, and vastus intermedius. They are located on the front of the thigh and are responsible for knee joint extension.
Hamstrings: The hamstrings consist of the biceps femoris, semitendinosus, and semimembranosus. They are located on the back of the thigh and aid in hip joint extension and knee joint flexion.
Stifle (Knee) Muscles
Popliteus: The popliteus is a small muscle located at the back of the stifle joint. It aids in stabilising and flexing the stifle joint.
Gastrocnemius: The gastrocnemius, also known as the calf muscle, is located on the back of the lower leg. It is responsible for flexing the tarsal joint and extending the digits.
Crus (Shank) Muscles
Tibialis Anterior: The tibialis anterior is located on the front of the lower leg and aids in flexing the tarsal joint.
Extensor Digitorum Longus: This muscle runs along the front of the lower leg and is responsible for extending the digits.
Fibularis (Peroneal) Muscles: The fibularis muscles consist of the fibularis longus and fibularis brevis. They are located on the outer side of the lower leg and aid in tarsal joint flexion and support of the foot during locomotion.
Tarsal and Digital Muscles
These muscles are smaller and play a role in the movement and stability of the tarsal and digital (toe) joints.
The hindlimb muscles work in harmony to allow dogs to perform essential activities, such as walking, running, jumping, and maintaining balance during various movements. Proper strength, coordination, and flexibility in these muscles are crucial for maintaining the overall health and mobility of the canine hindlimb.
Spinal Column Muscles
The spinal column, also known as the vertebral column or backbone, is a vital part of the skeletal system that provides support, stability, and protection to the spinal cord and nerves. The muscles associated with the spinal column can be categorised based on their locations and functions. Here is an outline of the major muscle groups that support and move the spinal column:
Erector Spinae Muscles
Iliocostalis: This muscle group consists of the iliocostalis lumborum, iliocostalis thoracis, and iliocostalis cervicis. They are located on the lateral aspect of the vertebral column and function to extend and laterally flex the spine.
Longissimus: The longissimus muscle group includes the longissimus thoracis, longissimus cervicis, and longissimus capitis. They are located on the back of the vertebral column and aid in extension and lateral flexion of the spine.
Spinalis: The spinalis muscle group consists of the spinalis thoracis, spinalis cervicis, and spinalis capitis. They are located closer to the midline of the vertebral column and assist in extension and lateral flexion.
Transversospinalis Muscles
Semispinalis: The semispinalis muscle group consists of the semispinalis thoracis, semispinalis cervicis, and semispinalis capitis. They are located deeper than the erector spinae muscles and function to extend and rotate the spine.
Multifidus: The multifidus muscles run along the vertebral column and play a crucial role in providing stability and proprioception to the spine.
Rotatores: The rotatores muscles are a group of short muscles that aid in rotation and stabilisation of the vertebral column.
Interspinales and Intertransversarii Muscles
These smaller muscles are located between adjacent vertebrae and assist in stabilising and controlling movement in the spine.
The muscles of the spinal column work together to maintain posture, support the weight of the body, and facilitate movements such as flexion, extension, lateral flexion, and rotation of the spine. Proper strength and coordination of these muscles are essential for maintaining the integrity and functionality of the spinal column, helping dogs to perform various activities with ease and stability.
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