The Skeletal System

Introduction -The Basics The skeleton, composed of bones, cartilages, joints, and ligaments, accounts for about 20% of body mass.   There are 206 bones in the human body.

The axial skeleton forms the long axis of the body and includes the bones of the skull, vertebral column, and rib cage. There are 80 bones in the axial skeleton.

The Appendicular skeleton consists of the bones of the upper and lower limbs, and the shoulder bones and hip bones. There are 126 bones in the Appendicular Skeleton.

The Axial Skeleton The skull consists of two sets of bones – the cranium and the facial bones. There are eight cranial bones and fourteen facial bones.  The joints between bones of the skull are immovable and called sutures.

The Cranial Bones of the Skull Occipital bone Parietal bones Frontal bone Temporal bones Sphenoid Ethmoid

The Skull The Adult Skull

The Skull The Adult Skull

The Skull The Adult Skull

The Skull Superficial Facial Bones Maxillae = maxillary bones Lacrimal Nasal Zygomatic Mandible

The Axial Skeleton Only the mandible is attached by a freely movable joint. The hyoid bone is the only bone in the body that does not articulate (match up with) another bone. The hyoid bone acts as an attachment point for several muscles that help with speech and swallowing. The hyoid bone is attached to the skull by ligaments.

The Axial Skeleton The vertebral column consists of vertebrae separated by disks of fibro-cartilage. 7 cervical vertebrae   12 thoracic vertebrae   5 lumbar vertebrae   The bony thorax forms a cage to protect major organs

SPINAL (VERTEBRAL) COLUMN The spinal column (or vertebral column) extends from the skull to the pelvis and is made up of 33 individual bones termed vertebrae.

The Axial Skeleton The bony thorax is made up of three parts: 1)Sternum 2)Ribs 3)Thoracic vertebrae

The Axial Skeleton You have three different types of ribs True ribs are the first seven pairs of ribs. True ribs attach directly to the sternum by costal cartilages. False ribs are the next five pairs. They either attach indirectly to the sternum or not at all. Floating ribs are the last two pairs of false ribs. They lack sternal attachments.  

The Appendicular Skeleton The 3 parts of the appendicular skeleton are: 1)Limbs (appendages) 2)Pectoral girdle (shoulder) 3)Pelvic girdle (pelvis)

The Appendicular Skeleton The pectoral girdle (or shoulder) is composed of two bones 1)Clavicle – collarbone 2)Scapula – Shoulder blade   The clavicle and the scapula allow the upper limbs to have free movement

The Appendicular Skeleton The pelvic girdle is made up of the hip bones.   The “hip bones” are composed of three pair of fused bones – the ilium, ischium, and pubic bone.

The Appendicular Skeleton The total weight of the upper body rests on the pelvis. The pelvic girdle protects several organs – the reproductive organs, the urinary bladder, and part of the large intestine.

The Appendicular Skeleton The hand contains three types of bones: 1)Carpals – wrists 2)Metacarpals – palm 3)Phalanges - fingers

The Appendicular Skeleton The arm is formed from a single bone, the humerus. The forearm has two bones: the ulna and radius

The Appendicular Skeleton The thigh has one bone – the femur.   The lower leg has two bones – the tibia and fibula.

The Appendicular Skeleton The foot has three types of bones: 1)Tarsals – ankle 2)Metatarsals – sole 3)Phalanges - toes

The Axial Skeleton The axial skeleton Forms the longitudinal axis of the body Has 80 bones The skull: 8 cranial bones 14 facial bones Bones associated with the skull: 6 auditory ossicles the hyoid bone

The Axial Skeleton The axial skeleton The vertebral column 24 vertebrae (singular = vertebra) The sacrum The coccyx The thoracic cage 24 ribs The sternum

The Axial Skeleton The Axial Skeleton

The Axial Skeleton Figure 7–1 The Axial Skeleton

The Cranial Bones of the Skull The Occipital Bone Functions of the occipital bone Forms the posterior and inferior surfaces of the cranium Articulations of the occipital bone Parietal bones Temporal bones Sphenoid First cervical vertebra (atlas)

The Axial Skeleton Functions of the Axial Skeleton Supports and protects organs in body cavities Attaches to muscles of Head, neck, and trunk Respiration Appendicular skeleton

The Skull The skull protects The skull contains 22 bones The brain Entrances to respiratory system Entrance to digestive system The skull contains 22 bones 8 cranial bones: Form the braincase or cranium 14 facial bones: Protect and support entrances to digestive and respiratory tracts

The Skull Cranial and Facial Subdivisions of the Skull

The Skull Cranial Bones Facial Bones Enclose the cranial cavity Which contains the brain And its fluids, blood vessels, nerves, and membranes Facial Bones Superficial facial bones For muscle attachment Deep facial bones Separate the oral and nasal cavities Form the nasal septum

The Skull The Adult Skull

The Skull The Adult Skull

The Skull The Sectional Anatomy of the Skull.

The Skull The Sectional Anatomy of the Skull