Musculoskeletal System

What are the functions of the skeleton?

Support, protection, movement, storage, blood cell formation

What is the role of the skeleton in support?

The skeleton provides a supporting framework for the soft parts of the body. The bowl of the pelvis supports the abdominal organs and most of the internal organs are attached to the skeleton either directly or by connective tissue

What is the role of the skeleton in protection?

The skeleton protects delicate internal organs. The rib cage protects the heart and lungs, the skull protects the brain, the pelvis protects the bladder and female reproductive organs and the vertebral column protects the spinal cord.

What is the role of the skeleton in movement?

The skeleton serves as a place of attachment of muscles that are used in movement. They also form joints which provide a system of levers which enable all or part of the body to be moved in response to a stimulus.

What is the role of the skeleton in storage?

The skeleton stores the minerals, calcium and phosphorous. These minerals are laid down as calcium phosphate in the matrix of compact bone, making the matrix hard. As these minerals are needed, they are reabsorbed from bone tissue. The skeleton also contains stores of fat found in the yellow bone marrow.

What is the role of the skeleton in blood cell formation?

The flat bones (ribs, sternum, pelvis, vertebrae) produce new red blood cells to replace old and damaged ones.

What are flat bones?

Flat bones contain a layer of spongy bone sandwiched between parallel plates of compact bone. For example, ilium, scapula, ribs and skull. (protects internal organs)

What are long bones?

Long bones consist of a shaft (diaphysis) composed of compact bone which surrounds a central cavity or canal (medullary canal) containing yellow bone marrow. Two ends (epiphysis) which are enlarged contain mostly cancellous bone and red bone marrow. For example, the femur. (supports weight and allows for movement)

What are irregular bones?

Irregular bones have a similar structure to flat bones, but an irregular shape. For example, vertebrae. (variable nature helps to protect different structures)

What are short bones?

Short bones contain spongy bone surrounded by a thin layer of compact bone. They have no shaft, appearing box-like in shape. For example, carpals, tarsals and phalanges. (provide stability and allows movement)

What are sesamoid bones?

Sesamoid bones develop with tendons, where a tendon crosses over boney ridges. For example, the patella. (protects tendons)

What is the axial skeleton?

Principal supportive structure of the body oriented along median longitudinal axis.

What bones are included in the axial skeleton?

Skull, vertebrae (including sacrum and coccyx), sternum, ribs and hyoid bone.

What is the appendicular skeleton?

Provides a movable frame for upper and lower limbs.

What bones are included in the appendicular skeleton?

Pectoral girdle, bones of arms, wrists, hands, pelvic girdle, bones of legs, ankles and feet.

Why does the cranium have multiple bones?

To provide structure and protection.

How are the bones of the cranium prevented from moving in relation to one another?

They are fused together by strong, fibrous, elastic tissues called sutures.

What are the features of the skull that help protect the eyes?

Orbit, 6 extrinsic eye muscles, upper and lower eyelids, lacrimal apparatus, lens, and aqueous humor.

What is the function of the foramen magnum?

It is a passage of the central nervous system through the skull connecting the brain with the spinal cord.

Do the eye sockets face forwards, sideways, upward or downward?

Forwards.

How many cervical vertebrae are there?

7.

How many thoracic vertebrae are there?

12

How many lumbar vertebrae are there?

5

How many bones make up the sacrum?

5 fused together

How many bones make up the coccyx?

4 fused together (can be 3 or 5)

Thinking about movement, why are the atlas and axis vertebrae different to the others?

Allow for movement in head and neck, separated by synovial joint, not an intervertebral disk.

What is the purpose of the hole through each vertebra?

Forms hollow tube for spinal cord and nerve roots

Suggest a reason for the decrease in size of the holes in the vertebrae.

To accommodate the decreasing size of the spinal cord

What is the function of the discs of cartilage between adjacent vertebrae?

Act as shock absorbing system

What are the flat bones which are attached to the thoracic vertebrae?

Ribs

Suggest a reason for the longer projections on the lumbar vertebrae.

Designed to carry most of the body's weight and allow for certain movements, e.g. lifting things, therefore cause for back pain.

What was the coccyx once?

Remnants of a vestigial tail - where the tail was supported

Examine the vertebral column from the side. Describe its curvature. Suggest reasons for this shape. Would you expect a chimpanzee to have the same curves?

S-shaped to absorb and distribute stresses from everyday life. Chimpanzees have different curves.

What is the rib cage?

Bony structure surrounding the thoracic cavity.

How are the ribs attached to the sternum? Why are they attached in this way?

Intercostal cartilages

What organs of the body does the rib cage protect?

The heart and the lungs

At the bottom of the ribcage are "false ribs" and "floating ribs". How are these bones different to "true ribs"?

True ribs - attach to the sternum in the front - first 7 ribs;
False ribs - do not directly connect to the sternum - lower 8, 9, 10 ribs;
Floating ribs - half the size of the others & do not reach to the front of the body - 11, 12

What bones make up the pectoral girdle?

Made up by the scapula and paired clavicles

Why does the upper bone of the arm have the nickname, "the funny bone"?

Because of the funny feeling you get after you hit it

The thumb is described as being opposable. What does this mean?

Capable of facing and touching the other digits on the same hand

What bones make up the pelvic girdle?

Sacrum, coccyx and pelvis

What is the function of the patella?

Improves the effective extension capacity of the quadriceps muscle by increasing the moment arm of the patellar ligament

Which bone is larger - the tibia or the fibula?

Tibia

What are some differences between the pectoral girdle and the pelvic girdle? Why are the limb girdles different?

The pectoral girdle is made up of the clavicle and the scapula, while the pelvic girdle consists of the hip bones. The main difference between these two girdles is their size and shape.

Unlike other primates, the human big toe is non-opposable. Why?

To favour a pronounced arch to enhance our ability to walk and run with an upright posture

What difference would you expect to see in the pelvic girdle of a male and a female human? Why?

The female human's pelvic girdle is wider to allow for easier childbirth.

What is the pelvic girdle made up of?

Consists of the 2 hip bones, sacrum, and coccyx.

What is the function of the pelvic girdle?

The pelvis is strong and rigid and allows for transfer of weight from the upper axial skeleton to the lower appendicular components of the skeleton during movement. The large bones also provide points for attachment of muscles and ligaments used in location and protect the organs in the abdominopelvic area.

What is the pectoral girdle made up of?

Consists of clavicle and scapula.

What is the function of the pectoral girdle?

Attach upper limb to sternum of the axial skeleton.

What does the arrangement of the bones in the pelvic girdle give?

Gives extensive mobility - it allows for abduction, adduction, flexion, extension and rotation. It's mobility comes at the expense of its stability.

What is the vertebral column made up of?

Consists of 33 vertebrae separated by fibrocartilage called intervertebral discs.

What is the function of the vertebral column?

Protect the spinal cord, the delicate bundle of nervous tissue that carries messages between the brain and the rest of the body.

How many subsections is the vertebral column divided into?

5.

What are the subsections of the vertebral column?

Cervical, thoracic, lumbar, sacrum, coccyx.

What is the general structure of a vertebra?

Body, vertebral arch, vertebral foramen, spinuous process, and transverse process.

What are the cervical vertebrae?

Vertebrae in the neck region.

What is the size of each cervical vertebra and why?

Each vertebra has a small body, reflecting the fact that they carry the least amount of body weight

What is the spinous processes in cervical vertebra?

The spinuous processes of the C3-C6 vertebrae are short, but the spine of C7 is much longer. You can find these vertebrae by running your finger down the midline of the posterior neck until you encounter the prominent C7 spine located at the base of the neck.

What is the C1 vertebra called and why?

Atlas who was the god who supported the heavens on his shoulders

How is the C1 vertebra different?

The C1 vertebra does not have a body or spinous process. Instead it is ring-shaped

What is the function of the C1 vertebra?

Supports the skull

What is the C2 vertebra called and why?

Axis, because it serves as the axis for rotation when turning the head toward the right or left

What is the bony projection on the C2 vertebra called?

Dens, it extends upward from the vertebral body

What distinguishes thoracic vertebrae from cervical vertebrae?

Larger body and downward angled spinous process

What do most thoracic vertebra have?

a facet on each side where a rib is attached

What are the floating ribs?

Ribs that do not attach at T11 and T12

What is the relative size of lumbar vertebral bodies and why?

Large as they carry the greatest amount of body weight, and therefore, are characterised by large, thick, vertebral bodies.

What short transverse processes and spinous processes do lumbar vertebrae have?

Short transverse processes and short blunt spinous processes that projects horizontally

Where is the cervical vertebrae located?

Neck

Where is the thoracic vertebrae located?

Chest

Where is the lumbar vertebrae located?

Lower back

What are the relative sizes of vertebral foramen?

Cervical - large
Thoracic - medium
Lumbar - small

What is the relative size of vertebral body?

Cervical - small
Thoracic - medium
Lumbar - large

What are some distinguishing features of the cervical vertebrae?

First 2 are different, atlas has no spinous process, axis has dens

What are the distinguishing features of T11 and T12?

Floating ribs

What are the distinguishing features of the transverse processes and spinous process in the lumbar vertebrae?

Short

What is the sacrum?

Triangular-shaped bone formed by fusion of 5 sacral vertebrae. It is thick and wide across the top where it is weight bearing and then tapers down to a non-weight bearing apex.

What is the coccyx?

Tailbone derived from fusion of 4 small vertebrae. It articulates with the below the sacrum.

When do the fusions of sacrum and coccyx start?

Age 20

When are the fusions of sacrum and coccyx completed?

Middle age

Is the coccyx weight bearing in standing position?

No, but may receive some body weight when sitting

What are spinal curves?

Three curves in the human spine that create an S-shape when viewed from the side.

What are the 3 curves of the spine?

The cervical curve bends slightly inward
The thoracic curve bends outwards
The lumbar curve bends inward

What is the purpose of spinal curves?

Even distribution of weight and flexibility of movement, allowing humans to stand upright and walk on two legs.

What happens to the lumbar curve when wearing high heel shoes?

It flattens as the lower body is forced forwards, causing the upper body to lean back as a counterweight. The poor alignment leads to muscle overuse, and back pain.

What type of bone is the cranium?

Flat bone

What type of bone is the humerus?

Long bone

What type of bone is the patella?

Sesamoid bone

What type of bones are the carpal bones?

Short bones

What type of bones is the pelvis bone?

Flat bone

Suggest why the wrist is composed of short bones

Short bones provide stability but also allow for movement so that the action of flexion and extension of the hand can occur.

What is the Diaphysis?

Hollow shaft of strong compact bone

What is the Medullary cavity?

Cavity in the diaphysis that stores bone marrow. AKA marrow cavity.

What is the Periosteum?

Dense, white, fibrous covering on the outer surface of the diaphysis

What does the periosteum provide?

Provides a good blood supply to the bone and point for muscle attachment

What is the Epiphysis?

Enlarged ends of a long bone

What does the compact bone surround?

Surrounds a central region of spongy or cancellous bones in the epiphysis

What is spongy bone?

Large pores filled with bone marrow in the epiphysis

What is the Articular cartilage?

Smooth cartilage covering each epiphysis