The Skeletal System

Axial Skeleton

• The axial skeleton includes the bones of the skull, vertebrae, rib cage
• The axial skeleton forms the central part of the skeleton.

Appendicular Skeleton

• The appendicular skeleton includes the bones of the upper and lower limbs, shoulder girdle, and pelvic girdle
• The appendicular skeleton includes the "appendices" or things that are stuck on.

Skull Bones

• At the front of the skull is the frontal bone.
• The parietal bone forms the wall of the skull.
• The temporal bone is located on the side of the skull.
• The occipital bone is at the back of the head.
• The sphenoid bone is located inside the skull.
• The maxilla and mandible are bones of the face.
• The zygomatic arch is made up of the zygoma, frontal bone, maxilla, and temporal bone.

Hyoid Bone

• The hyoid bone is located in the neck and is U-shaped
• The hyoid bone is a site of attachment for muscles and ligaments.
• These muscles can pull on the hyoid bone to raise and lower the larynx.
• The hyoid bone gives the tongue and larynx more mobility for speaking, eating, and swallowing.
• Forensic context: hyoid bone may be broken if someone's strangled but not necessarily if hung.

Vertebrae

• There are seven cervical vertebrae in the neck.
• There are 12 thoracic vertebrae that match the 12 ribs
• There are five lumbar vertebrae in the lower back.
• The sacrum is a fusion of vertebrae.
• The coccyx is made up of the remaining bones of the vestigial tail.

Thoracic Cage

• The ribs form the thoracic cage with cartilage and the sternum.
• The sternum has three parts: the manubrium, body, and xiphoid process.
• The thoracic cage is involved in breathing and protects the organs.

Shoulder Girdle

• The shoulder girdle comprises the clavicle and scapula.
• The clavicle is a slender bone that runs from the sternum.
• The scapula is a flat bone.
• Together they make a socket for the glenohumeral joint.
• The shoulder girdle is very mobile and allows for a greater range of movement of the upper limb.

Upper Limb

• The humerus is the first long bone of the upper limb.
• The elbow joint connects the humerus to the ulna and radius.
• The ulna forms the hinge joint with the humerus.
• The radius can spin around the ulna, allowing pronation and supination.

Wrist and Hand

• The bones of the wrist are called carpal bones.
• There are eight carpal bones arranged in two rows of four.
• The metacarpals are the long bones in the hand.
• The phalanges are the bones of the fingers.
• The thumb has two phalanges (proximal and distal), while the other fingers have three (proximal, middle, and distal).

Pelvis

• The pelvis is made up of three bones: the ilium, ischium, and pubis.
• These bones fuse together at the acetabulum.
• The ilium is the wing of the pelvis.
• The ischium is the bone you sit on, specifically the ischial tuberosities.
• The pubis is the bone at the front of the pelvis.

Lower Limb

• The femur is the longest bone in the body
• The neck of the femur comes in at an angle.
• The greater trochanter is a large, lumpy part of the femur where muscles attach.
• The patella (kneecap) is a sesamoid bone within the tendon of the quadriceps muscle.
• The patella gives a mechanical advantage to the muscle by pushing it away from the joint.
• The tibia is the large bone of the lower leg that articulates with the femur at the knee joint.
• The fibula is the smaller bone of the lower leg.

Ankle and Foot

• The tarsus is the group of bones forming the ankle.
• There are seven tarsal bones.
• The calcaneus (heel bone) is a large bone that bears a lot of weight.
• The talus is the bone of the ankle joint.
• The navicular, cuboid, and cuneiform are other bones of the tarsus.
• The metatarsals are the long bones of the foot.
• The phalanges are the bones of the toes.
• The big toe has two phalanges (proximal and distal), while the other toes have three (proximal, middle, and distal).