Zoology (Translated Book) Locomotion and Body Movement PDF

# Zoology (Translated Book) ## Locomotion and Body Movement Locomotion and movement are the important properties of living beings. For these two actions, 3 organ systems play active roles: skeletal system, muscular system, and nervous system. Movement, searching for food, self-defense, reproduction,...

# Zoology (Translated Book) ## Locomotion and Body Movement Locomotion and movement are the important properties of living beings. For these two actions, 3 organ systems play active roles: skeletal system, muscular system, and nervous system. Movement, searching for food, self-defense, reproduction, etc. every work is related to the musculo-skeletal system. By the contraction and expansion of the musculo-skeleton, organs or parts of the body move. The hard framework, which bears the body weight, is the skeletal system, and the part covering the skeletal system is the muscular system. In this chapter, the combined action of bones, cartilages, and muscles forming the skeletal system and fracture of bones and injuries of joints are described. ## Human Skeletal System The system formed by connective tissues like bones and cartilages originating from the embryonic mesoderm, which gives a definite shape to the body, carries its weight, provides surface for muscle attachment, and protects fragile organs by forming the framework of the body, is called the skeletal system. ## Classification of the Skeletal System Human skeleton is divided into the following three types: 1. **Exoskeletal system**: These can be seen from outside the body. These originate from the epidermis of the skin. That is why they are called epidermis-derived organs. Nails, teeth, hair, etc. are examples. 2. **Endoskeletal system**: By skeleton we usually understand the endoskeleton. It is formed of bones, cartilages and ligaments. These are not visible from outside of the body. It is of mainly 2 types - * Axial skeleton * Appendicular skeleton 3. **Splanchnic skeletal system**: Though it is considered part of the endoskeleton, it can be classified separately. Cartilage of larynx, trachea, bronchi, etc. are examples. ## Functions of the skeletal system ### Mechanical functions 1. **Formation of body structure**: skeletal system forms the structure of human body and provides definite shape. 2. **Protection**: Important organs of the human body, like brain, lungs, heart, spinal cord, etc. are protected within the specially formed skeleton. 3. **Providing surface for muscle attachment**: Most of the muscle, ligament and tendon of the body attaches to the skeleton and helps in organ movement. 4. **Locomotion**: Plays the main role in forming joint and attachment to muscles that helps in locomotion. 5. **Weight transmission**: Carries the weight of the body by keeping the muscles attached with skeletons. ### Physiological functions 6. **Production of blood corpuscles**: in a grown human body, the main tissue for producing blood is red bone marrow. Bone marrow present in sternum, ribs, vertebrae, skull and in the head of femur and humerus produce red blood corpuscles. About 26 lac RBC are produced from the bone marrow at every second. Other than continuously producing RBC, red bone marrow also produces platelets and holds macrophages. 7. **Respiration & Hearing**: Thoracic cage helps in inspiration-expiration, and ossicles of the middle ear help in hearing. 8. **Prevention of disease**: Reticulo-endothelial system of the bone takes part in preventing diseases. 9. **Store minerals**: Calcium, phosphorus and magnesium are stored in the bones and are released in the blood if needed. ## Components of skeletal system Skeletal system is formed of 5 types of fibrous and mineral rich components. 1. **Bone**: Bone is a rigid connective tissue present in the skeletal system that is mainly formed of calcium salt. 2. **Cartilage**: Cartilage is a strong but elastic type of connective tissue in the skeletal system. It contains a semi-translucent elastic matrix called condrin in which cartilage cells are scattered. 3. **Ligament**: Ligament is a dense, white colored fibrous and elastic band that joins one bone with another. These help to hold different organs in the correct position. 4. **Tendon**: Tendon is dense, tough, white colored, flexible and nonelastic fibrous connective tissue that are positioned at the ends of muscles and creates the connection between bones and cartilages. 5. **Joint**: The place of junction that a bone forms while attaching with another bone is called joint. Due to joints, it becomes easy to move different organs of the body to different levels that results in locomotion, movement, weight bearing and different actions. ## Main parts of the skeletal system A human child has **300 bones** in its body when it is born. But the adult skeleton is formed of **206 bones**. Cartilage is present at different places of the bone. Human skeleton can mainly be divided into *two parts*. They are: 1. **Axial skeleton**: The parts of the skeleton system that are located in the longitudinal axis, are called *axial skeleton*. Total **80 bones** form the axial skeleton. Skull, vertebral column and thoracic cage form the axial skeleton of the body. 2. **Appendicular skeleton**: The parts of the skeletal system that are present symmetrically on two sides of the axial skeleton, are called *appendicular skeleton*. Total **126 bones** are present in the appendicular skeleton. Pectoral girdle, forelimb, pelvic girdle and hind limbs form appendicular skeleton. The different parts of the skeletal system formed by 206 bones are shown in the chart below: ### Human skeletal system | Axial skeleton (80 bones) | Appendicular skeleton (126 bones) | | -------------------------- | ------------------------------ | | Skull (29) | Upper Limb (60) | | Spine (26) | Lower limb (60) | | Thoracic cage (25) | | | | Pectoral Girdle (4) | | | Pelvic Girdle (2) | | | | **Skull (29)** * Cranial bones (8) * Facial Bones (14) * Ear Ossicles (6) * Hyoid (1) **Spine (26)** * Cervical (7) * Thoracic (12) * Lumber (5) * Sacrum (1) * Coccyx (1) **Thoracic cage (25)** * Ribs (24) * Sternum (1) **Pectoral Girdle (4)** * Scapula (2) * Clavicle (2) **Upper Limb (60)** * Humerus (2) * Radius (2) * Ulna (2) * Carpal (16) * Metacarpal (10) * Phalanges (28) **Pelvic Girdle (2)** * Innominate or hip bone (2) **Lower limb (60)** * Femur (2) * Patella (2) * Tibia (2) * Fibula (2) * Tarsal (14) * Metatarsal (10) * Phalanges (28) ## Function of the Facial bones The facial bones provide the structure of the face by being well decorated and form cavity for eyes, ears, nose, and mouth. Eyes, ears, nose, and teeth are well-arranged in these cavities which actively participate in vital organ formation and protection. ## B. Vertebral Column A flexible and bony part which gives the structural framework and support to the body axis, extends from atlas to coccyx and is formed of a number of vertebrae enclosing the spinal cord is called the *vertebral column*. It is also called *spine*, *spinal column*, *back bone*, etc. **33 irregular bone fragments** form the *vertebral column*. Each bone fragment of the column is called *vertebra* (plural-*vertebrae*). ## Structure of a Typical Vertebra Vertebrae of different regions or even of the same regions may vary from one another. Yet, all the vertebrae are formed on the basis of some fundamental structures. An ideal vertebra (mid-thoracic vertebra) is described below. 1. **Centrum or Vertebral Body**: It is the largest and the thickened anterior part of a vertebra, which looks like a segment of oval rod. Centrums of the adjacent vertebrae are attached by symphysis (formed of cartilage) or intervertebral disc. Centrum is formed of hard, thick, and spongy bone. 2. **Arch**: It is a ring-like structure situated in the dorsal surface of the vertebral body. It contains the following parts. * **Pedicle**: It is a short and stout projected part from either side of the postero-lateral part of the vertebral body. * **Transverse process**: It is the lateral projections from the junction of the lamina and pedicle on both sides. * **Lamina**: It is a wide, flat, oblique and sloping part in between the transverse and spinous process present on both sides. * **Articular process**: From the junction of the lamina and pedicle of both sides, a superior and an inferior articular process is formed. Superior articular process of one vertebra articulates with inferior articular process of the other. * **Spinous process**: It is a mid-line projection pointing downwards, formed from the junction of attachment of the lamina of two sides. This process of 2nd to 6th cervical vertebra is bifid. **Cervical Vertebra (7)** **Thoracic Vertebra (12)** **Lumber Vertebra (5)** **Sacrum (5)** **Coccyx (4)** ## Vertebral Foramen and Canal The notches present in the upper and lower aspect of the pedicle together form the *intervertebral foramen* or *neural foramen*. Blood vessels and spinal nerves pass through this foramen. The large foramen of the vertebra which contains centrum/body in front, arch at behind, and pedicles on both sides is called *the vertebral foramen*. The vertebral foramen of all the vertebrae together forms the *vertebral canal*. Inside the vertebral canal spinal cord with the membrane or meninges and blood vessels remains protected. ## Types of vertebrae According to the position, vertebra is divided into 5 regions: 1. **Cervical vertebrae - 7** 2. **Thoracic vertebrae - 12** 3. **Lumbar vertebrae - 5** 4. **Sacral vertebrae - 1** (5 bones are fused) 5. **Coccygeal vertebrae - 1** (4 bones are fused) **TOTAL................ .........26** In adult life, sacral bones fuse to form one sacrum and coccygeal bones fuse to form a coccyx. So, the total number of vertebral bones becomes 26. ## Functions of Vertebral Column * Acts as a flexible and strong support of the body trunk for proper movement of the body trunk. * Encloses and protects the spinal cord and spinal nerve roots. * Supports the head and acts like a pivot. * Acts as the axis of the body by forming articular surface for the ribs. * Builds the structure of the body and plays important role in the movement. ## C. Thoracic Cage: The ribs of the body form a cage like structure by connecting to the thoracic vertebra by one end and to sternum by another end. This structure is called the *thoracic cage*, The thoracic cage is formed of one sternum, 12 pairs of ribs, and 12 thoracic vertebrae. 1. **Sternum**: The flattened bone in front of the thoracic cage is *Sternum*. Ribs are connected to the lateral portion of it. It consists of 3 parts. They are as follows: * **Manubrium**: This is the triangular portion at the top. Clavicle and 1 rib forms a joint with it. * **Body**: It is the long, flattened, and hard middle portion. 2nd to 7th rib are connected to it. * **Xiphoid process**: It is the small and narrow portion situated at the bottom. Initially it is formed of cartilage, but later it converts into bone at adult age. 2. **Ribs**: These are flattened, long and curved bones. These are connected to the side of thoracic vertebra. Following parts are seen in rib: * **Capitulum**: It forms the head of the rib. Ribs are connected to centrum of thoracic vertebra by it. * **Tubercle**: Tubercle is located just after the head. It is a small projected dorsal part. Ribs are connected to the transverse process of the same thoracic vertebra by it. * **Angle**: The part of the rib which expands anteriorly by curving, it is called angle. * **Shaft**: The long portion after the angle which is situated in front of the body is called shaft. * **Costal cartilage**: The connecting part between the ribs and sternum is *costal cartilage*. It is cartilaginous. The ribs are categorized into 3 categories. They are: * **True ribs**: These are 7 pairs in number. These are 1st to 7th ribs. Originates from thoracic vertebra and later connects with the sternum. Cartilage is found between the junction of rib and sternum; these are called costal cartilage. * **False rib**: These are 3 pairs in number. These are 8th, 9th, and 10th rib. These originates from 8th, 9th, and 10th thoracic vertebra respectively, and they attach with 10th pair of ribs instead of the sternum. * **Floating ribs**: These are 2 pairs in number and originates from 11th and 12th thoracic vertebra and remain floating. 3. **Thoracic Vertebra**: The vertebra which are situated in the thorax region are called *thoracic vertebra*. Structure of these are almost same. There is centrum, vertebral arch, spinal process, transverse process, vertebral foramen and 3 facets for articulating with ribs in each vertebra. ## Function of the Thoracic Cage It protects the important organs of respiration and blood circulation. It participates in inspiration-expiration (respiration) by contracting during inspiration and relaxing during expiration. ## Appendicular Skeleton The bones of superior extremity/upper limb (two arms and pectoral girdle) and inferior extremity/lower limb (two legs and pelvic girdle) together are called *appendicular skeleton*. ## Bones of Superior Extremity It is formed of *pectoral girdle* and *two forelimbs*. There are 32 bones on each side in the superior extremity, that is, in total 64 bones. ### A. Pectoral Girdle 2 pairs of bones form the pectoral girdle of human, they are a pair of clavicles and a pair of scapulae. * **Clavicle**: It looks like the italic letter f and is a curved bone. It has a body and 2 ends, *sternal* (which articulates with the manubrium) and *acromial process* (articulates with the scapula). * **Scapula**: Scapula looks flat and is a triangular bone. It has an anterior or costal surface, one posterior surface or coracoid process, one acromial process, and one concave articular surface named glenoid cavity. Anterior surface remains facing towards the ribs. It contains a concave surface named subscapular fossa. Head of the humerus articulates with the glenoid cavity. Spine of scapula is present on the posterior surface which divides the posterior surface into supraspinous and infraspinous fossa. ### B. Bones of forelimb or upper limb Two limbs hang from the shoulder region on each side of human body. They are called *forelimb*. Each forelimb consists of 30 small and large bones. Following bones are found in upper limb: 1. **Humerus**: The first bone of forelimb is called *humerus*. It is an elongated tubular bone. Its upper end has a smooth and circular head which articulates with the glenoid cavity of the scapula. Besides there are greater and lesser tubercles, and between them there is a groove called anatomical neck. The narrow part from which the shaft (body) of the humerus starts is called *surgical neck* (because this area is most prone to fracture during accident). There is a rough area in the middle region of shaft for the muscle attachment which is called the *deltoid ridge*. The ends of the shaft form epicondyle at the lower end. Below the epicondyles, there lies condyle which is divided into capitulum and trochlea. 2. **Radius-Ulna**: Middle part of the forelimb is formed of two tubular, elongated and closely placed bones, they are - radius and ulna. The inner bone is the ulna. Its upper end contains a coronoid process, and an olecranon process, a trochlear notch and a tuberosity. Lower end is divided into head and styloid process. Upper end of the radius contains a head with a groove, neck & tuberosity, and lower end contains articular surface for the carpel bones and a styloid process. Upper ends of radius and ulna are attached by annular muscles and rest of the part is connected by ante-brachial membrane. 3. **Carpal bones**: Wrist is formed of 8 variable shaped small carpal bones arranged in two rows, having 4 in each row. The row at proximal end (towards the base) contains scaphoid (navicular), lunate, triquetral, and pisiform and the distal end contains trapezium, trapezoid, capitate, and hamate bone. 4. **Metacarpal bones**: 5 bones forming the palm are called *metacarpals*. A metacarpal bones is a long and tubular bone, and contains a base, shaft, and a head. 5. **Phalanges**: The bones of the fingers are called *phalanges*. These are short and tubular. Thumb contains 2 phalanges and other fingers contain 3 phalanges each. ## Bones of Inferior Extremity It is formed of pelvic girdle and 2 legs. Lower limb of each side contains 31 bones; so, there are in total 62 bones. These are described below. ### A. Pelvic Girdle It is formed of *ilium*, *ischium* and *pubis*. These bones combine and form the *hip bone* in an adult human. 2 hip bones together form pelvic girdle. * **Ilium**: Ilium is divided into body and wing/ala. The edge of the wing is called *iliac crest*. The two-crest end into two elevated parts in the two ends which are called anterior superior iliac spine, and posterior superior iliac spine. Below these two, there are anterior inferior iliac spine and posterior inferior iliac spine. Besides, ilium also contains arcuate line, iliac fossa, gluteal line and an auricular surface (for sacral attachment). * **Pubis**: Pubis is divided into a body and two branches. These two branches are called superior and inferior rami (singular-ramus). Superior ramus contains a pubic tuberosity and a pubic crest. * **Ischium**: Ischium is formed of body, superior and inferior rami, ischial tuberosity, and ischial spine. The spine separates the large ischial groove from the smaller one. The pubic and ischial rami enclose the obturator foramen. The foramen is almost entirely covered by connective tissue membrane. There is a shallow part named acetabulum which is present at the junction of *ilium, ischium*, and *pubis*. Head of the femur is articulated here. ## Functions of Pelvic Girdle Giving support to the pelvis, urinary bladder, lower part of the intestine and pelvic organs, bearing weight and protecting them is its function. Head of the femur articulates with the acetabulum. ## Differences between Pelvic Girdle of Male and Female | Features | Male pelvic girdle | Female pelvic girdle | | -------------------- | ---------------------------------------------------------- | --------------------------------------------------- | | 1. Structure of bone | Heavy and larger | Light and smaller | | 2. Foramen of pelvis | Comparatively smaller | Mostly larger | | 3. Sacrum | Thin | Short, wide, and flat | | 4. Pubic symphysis | Shallow | Deep | | 5. Acetabulum | Large, laterally facing | Small, anteriorly facing | ## Differences between Ilium and Ileum | Ilium | Ileum | | ------------------------------------------ | ------------------------------------------------------------ | | 1. A special bone in the pelvic girdle of vertebrates. | 1. A part of the alimentary tract in all vertebrates and invertebrates. | | 2. Wing like shape | 2. Thin tubular structure | | 3. Formed of bone. | 3. Formed of different muscle layer | | 4. Keeps the femur attached with vertebral column. | 4. Helps in food digestion and absorption. | ## B. Bones of Hindlimb or Lower limb 1. **Femur**: First bone of hind limb is called *femur*. It is the longest bone of human body. Its upper end contains a circular head, neck, and greater & lesser trochanters. Body (shaft) is hard and tubular. Its posterior surface contains a rough spine. Lower end contains 2 condyles. Between the 2 condyles there is *intercondylar foramen*, articular surface for patella and there are two little elevated parts called *epicondyles*, one on each side of the lower end. In the lower end of the femur there is a triangular bone named *patella*. Patella is a sesamoid bone as it originates from the tendon of a muscle. The upper part of the posterior surface of Patella is articulated with femur and the lower part is articulated with tibia. 2. **Tibia-Fibula**: There are 2 bones in the leg at the middle region of the hindlimbs, they are - *tibia* and *fibula*. * **Tibia**: Tibia is thicker. It has two condyles in the upper part, an intercondylar eminence, and two articular surfaces for the articulation of femur and a tuberosity for the muscular attachment. Shaft/body of the tibia has 3 edges or borders. Its anterior border known as crest. There is a malleolus in the lower end of both the tibia which has an articular surface for the attachment of the talus (tarsal bone). * **Fibula**: Fibula looks like a long slender stick. Its head is pointed. Upper end has an articular surface for the attachment of tibia. Lower end contains a malleolus. 3. **Tarsal bones**: The bones which form the heel and posterior half of the sole are called *tarsus*. 5 different types of 7 *tarsus bones* are arranged in 3 rows. The tarsus are - one talus, calcaneus, cuboid, navicular and 3 cuneiforms. 4. **Metatarsal bones**: 5 small shaped *metatarsal bones* arranged in a row which forms the anterior portion of sole are called metatarsus. 5. **Phalanges**: Bones of the toes of the foot are called *phalanges*. There are in total 14 phalanges; 2 phalanges in each great toe and 3 phalanges in each other toe of both legs.