Introduction to Anatomy

• The Skeletal system is formed of bones, cartilages and joints

Human Anatomy

• Anatomy is derived from Greek, meaning to cut
• Anatomy is derived from Latin, meaning to dissect
• Levels of studying anatomy include Macroscopic or Gross, Microscopic and Radiological.
• Macroscopic or gross anatomy looks at anatomy
• Microscopic anatomy studies histology

Anatomical Positions

• Supine position: lying horizontally with the face and torso facing up
• Prone position: lying horizontally with the face and torso facing down
• Right lateral position: lying on your right side.
• Left lateral position: lying on your left side.

Anatomical Planes

• Sagittal (Longitudinal) Plane: Divides the body into right and left halves
• Median plane: Divides body into right and left halves
• Coronal (Frontal) Plane: Divides body into anterior and posterior parts
• Transverse (Axial) Plane: Divides body into upper and lower parts

Anatomical Terms of Position

• Superior means above
• Inferior means below
• Anterior (Ventral) means towards the front
• Posterior (Dorsal) means towards the back
• Medial means towards the midline of the body
• Lateral means away from the midline of the body
• Proximal means closer to the trunk of the body
• Distal means farther from the trunk of the body
• External (Outer) means outside
• Internal (Inner) means inside
• Superficial means closer to the surface
• Deep means farther from the surface

The Skeleton

• The skeleton represents 20% of body weight
• It has two subdivisions: axial and appendicular
• The axial skeleton has 80 bones
• The appendicular skeleton has 126 bones

Skeletal System

• Axial skeleton lies along the central axis of the body
• Axial skeleton is formed of the skull, vertebral column, and bones of the thoracic cage
• Appendicular skeleton consists of the bones of the upper and lower limbs, shoulder girdle, and pelvic girdle

The Skull

• The skull consisting of a cranial and a facial portion
• 8 bones comprise the Cranial portion
• 14 bones comprise the Facial portion

Cranial Portion of the Skull

• The cranial portion comprises of 8 flat bones
• They are articulated together by non-mobile strong fibrous joints called sutures
• Bones include one frontal, one occipital, one sphenoid, one ethmoid, two parietal, and two temporal bones

Facial Portion of the Skull

• The facial portion is made of 14 flat irregular bones joined by sutures
• These bones are two nasal, two zygomatic, two maxillary, two lacrimal, two palatine, two inferior nasal conchae, one vomer and one mandible

Skull Openings and Cavities

• The base contains a large opening called the foramen magnum for passage of the spinal cord
• The base also contains multiple small foramina for passage of nerves and blood vessels
• The anterior view contains openings and cavities for the orbit, the nose, and the mouth
• Fetal skull bones are not completely united but have membranes called fontanels
• Fontanels allow growth with age

Skull Sinuses

• The skull contains the paranasal air sinuses
• Bone contains air cavities that decrease the weight of the skull
• Clinical anatomy example is sinusitis

The Vertebral Column

• It is the central part of the skeleton responsible for supporting the head
• It encloses the spinal cord and transmitting the body weight
• The vertebral column consists of separate bones called vertebrae
• Some of the Vertebrae are fused

Vertebral Groups

• The number of vertebrae totals 33, divided into 5 groups: cervical, thoracic, lumbar, sacral, coccygeal
• There are seven cervical vertebrae
• There are twelve thoracic vertebrae
• There are five lumbar vertebrae
• There are five sacral fused into a single bone called SACRUM
• There are four coccygeal fused in single bone called COCCYX

Vertebrae Features

• Each vertebra is formed of the body located anteriorly, and the vertebral (neural) arch located posteriorly.
• The vertebral arch is formed of two pedicles, two laminae, one spine, two transverse and two inferior articular processes.
• Each vertebra has a vertebral foramen to allow the passage of the spinal cord
• The vertebrae are articulated with each other by the inter-vertebral discs

Vertebral Characteristics

• Cervical vertebra has bifid spinous process
• The first cervical vertebra is called atlas while C2 is axis
• Thoracic vertebra is characterized by the presence of articular surfaces
• Articular surfaces are on its body and transverse processes for articulation with ribs
• Lumbar vertebra is the largest
• Lumbar vertebra has kidney shaped body

Thoracic Cage

• The thoracic cage is formed of sternum anteriorly, 12 thoracic vertebrae posteriorly, and 12 pairs of ribs

Sternum

• The sternum anteriorly is a flat bone with three parts
• Three parts: manubruim, body, and xiphoid process

Ribs

• Ribs are classified into three groups
• True ribs (1st-7th) articulate to the sternum anteriorly and thoracic vertebrae posteriorly
• False ribs (8th, 9th and 10th) attached to each other anteriorly
• They are articulated posteriorlly to the thoracic vertebrae
• Floating ribs: (11th, 12th) articulated posteriorly to the thoracic vertebrae, are free anteriorly

Appendicular Skeleton Components

• Appendicular Skeleton components include the shoulder girdle, pelvic girdle, bones of the free upper limb, bones of the free lower limb

Shoulder Girdle

• The shoulder girdle comprised of two bones with the clavicle anteriorly and the scapula posteriorlly.

Pelvic Girdle

• The pelvic girdle is formed of the right and left hip bones
• Each hip bone is formed of three fused bones: ilium, pubis, and ischium

Upper Limbs

• The bones of the free upper limb include the humerus in the arm
• The bones of the free upper limb include the Radius and ulna in the forearm.
• The bones of the free upper limb include the Carpal bones (8 small irregular bones) in the wrist
• The bones of the free upper limb include the Metacarpal bones in the hand
• The bones of the free upper limb include the Phalanges, or 14 short irregular bones, in the finger

Lower Limbs

• The bones of the free lower limb include the femur in the thigh
• The bones of the free lower limb include the tibia and fibula in the leg
• The bones of the free lower limb include the tarsal bones (seven irregular bones) in heel and ankle
• The bones of the free lower limb include the metatarsal bones (5 bones in the heel), phalanges (14 bones in the toes (digits)).

Bone Classification By Shape

• Long bones: humerus, femur, tibia, fibula, radius, ulna
• Short bones: carpals and tarsals
• Irregular bones: vertebrae
• Flat bones: scapula, sternum, hip and bones of skull
• Sesamoid bones: the largest one is the patella

Function of Bones

• Functions of bones include support of the body and protection of soft organs.
• Functions of bones include movement due to attached skeletal muscles
• Functions of bones include storage of minerals and fats, as well as blood cell formation

Anatomy is the study of the structure of the human body, derived from Greek and Latin terms for 'to cut' and 'to dissect'. It explores the skeletal system, anatomical positions (supine, prone, lateral), and anatomical planes (sagittal, coronal, transverse). The levels of studying anatomy include macroscopic, Microscopic and radiological.