A&P Axial and Appendicular Skeleton

General Terms: Body

main part

General Terms: Head

enlarged end

General Terms: Neck

constriction between head and body

General Terms: Margin or Border

edge

General Terms: Angle

bend

General Terms: Ramus

branch off the body (beyond the angle)

General Terms: Condyle

smooth, rounded articular surface

General Terms: Facet

small, flattened articular surface

Ridges: Line or linea

low ridge

Ridges: Crest or crista

prominent ridge

Ridges: Spine

very high ridge

Projections: Process

Prominent projection

Projections: Tubercle

Small, rounded bump

Projections: Tuberosity or tuber

knob; larger than a tubercle

Projections: Trochanter

tuberosities on the proximal femur

Projections: Epicondyle

Upon a condyle (smooth, rounded articular surface)

Projections: Lingula

Flat, tongue-shaped process

Projections: Hamulus

Hook-shaped process

Projections: Cornu

Horn-shaped process

Openings: Foramen

Hole

Openings: Canal or meatus

Tunnel

Openings: Fissure

Cleft

Openings: Sinus or labyrinth

cavity

Depressions: Fossa

general term for a depression

Depressions: Notch

depression in the margin of a bone

Depressions: Fovea

little pit

Depressions: Groove or sulcus

deeper, narrow depression

Axial skeleton

Divided into three parts:

• Skull

• Vertebral Column

• Body Thorax

The skull

Made of two sets of bone: the cranium and facial bones

• the function of the cranium is to enclose and protect the fragile brain tissue

• the facial bones hold the eyes in an anterior position and allow the facial muscles to show our feelings

• the bones of the skull are held together by sutures (immovable joints)

• The mandible (jawbone) is the only skull bone that is attached with a moveable joint

sutures

immovable joints

Cranium

Consists of the following eight bones: frontal bone, left and right parietal bones, left and right temporal bone, occipital bone, sphenoid bone, ethmoid bone

Cranium Bones: Frontal bone

The frontal bone forms the forehead, the body projections under the eyebrows and the superior part of each eye’s orbit

Cranium Bones: Left and right parietal bones

• The parietal bones form most of the superior and lateral walls of the cranium

• they meet in the midline of the skull at the sagittal suture

• they form the coronal suture where they meet at the frontal bone

Cranium Bones: left and right temporal bone

• the temporal bones join the parietal bones at the squamous sutures

• the six important features of the temporal bone are

  • external auditory meatus

  • styloid process

  • zygomatic process

  • mastoid process

  • jugular foramen

  • carotid canal

Cranium Bones: Temporal Bone: External Auditory Meatus

A canal that leads to the eardrum and the middle ear

Cranium Bones: Temporal Bone: Styloid Process:

A sharp, needlelike projection that serves as an attachment point

Cranium Bones: Temporal Bone: Zygomatic Process

A thin bridge of bone that joins with the cheek bone (zygomatic bone) anteriorly

Cranium Bones: Temporal Bone: Mastoid Process

A rough projection full of air cavities that provides an attachment site for some muscles of the neck

Cranium Bones: Temporal Bones: Jugular Foramen

Allows passage of the large jugular vein, with drains the brain

Cranium Bones: Temporal Bone: Carotid Canal

Anterior to the jugular foramen; allows passage of the internal carotid artery, which supplies blood to most of the brain

Cranium Bones: Occipital Bone

• The bone forms the floor and back wall of the skull

• the bone joins the parietal bones at the lambdoid suture

• the large hole at the base of the skull is the foramen magnum

  • the function of this hole is to allow the spinal cord to connect with the brain

• Located lateral to the foramen magnum are the occipital condyles, whose function are to the rest on the first vertebra of the spinal column

Cranium Bones: Sphenoid bone

This butterfly shape bone forms part of the floor of the cranial cavity

Cranium Bones: Ethmoid bone

• forms the roof of the nasal cavity

• projecting from the superior surface of the bone is the crista galli

  • the outermost covering of the brain attaches to this projection

Facial Bones

• Fourteen bones compose the face (we will examine 13)

  • The bones: Maxillae(paired), Palatine bones (paired), Zygomatic bones(paired), Lacrimal bones (paired), Nasal Bones (paired), Vomer (single), Ethmoid bone (single),Mandible (single)

Facial Bones: Maxillae

• All facial bones except the mandible join the maxillae

• Forms the anterior portion of the hard palate

Facial Bones: Palatine bones

• These form the posterior portion of the hard palate

• Failure of these bones to fuse medially will result in cleft palate

Facial Bones: Zygomatic Bones

• These bones form the cheeks

• They also form the lateral walls of the orbits, or eye sockets

Facial Bones: Lacrimal bones

These have grooves in them that serves as a passageway for tears

Facial Bones: Nasal Bones

Describes as small rectangular bones forming the bridge of the nose

Facial Bones: Vomer

This bone’s name means “plow” and forms most of the nasal septum

Facial Bones: Ethmoid Bone

• Anterior to the sphenoid bone and forms the roof of the nasal cavity and medial walls of the orbit

• Involved with attachment of the brain and sense of smell

Facial Bones: Mandible

• also known as the jawbone

• this is the only freely movable joint in the skull

Vertebral column

• Made up of 26 irregular bones

  • at brith we have 33 bones, 9 of which fuse to form the sacrum and coccyx

  • Supports the skull

  • meets with the pelvis to transfer weight to the lower limbs

  • flexible

  • reinforced by ligaments

  • divided into five regions

    • cervical or c-spine

    • thoracic spine

    • lumbar spine

    • sacrum

    • coccygeal spine

Vertebral Column: Cervical Spine

• 7 vertebrae

• Numbered from superior to inferior; C1 - C7

Vertebral Column: Thoracic Spine

• 12 vertebrae

• T1 -T12

Vertebral Column: Lumbar Spine

• 5 vertebrae

• L1-L5

Vertebral Column: Sacrum

• 1 sacral bone

• Five bones fused together

Vertebral Column: Coccyx

• 1 bone

• 3-5 bones fused together

Secondary Curvature Number 1

Develops when babies start to hold up its head

Secondary Curvature Number 2

Develops when babies start walking

Primary Curvature (1 and 2)

Present at birth

More about curvature

The S-shaped curvature prevents shock to the head with motion. But various conditions exist that deviate from that shape.

• Lordosis - exaggeration of the concave curve of the lower spine

• Kyphosis - “hump back";” exaggeration of the convex curve in the thoracic spine

• Scoliosis - abnormal lateral and/or rotational curve of the spine

Vertebrae

General functions of the vertebrae:

• support the weight of the head and trunk

• protect the spinal cord

• spaces for the nerves to exit the spinal cord sites for muscle attachment

• movement of the head and trunk

Each vertebrae has a

Body: a body disk that bears weight

Arch: two parts that extend laterally and attached to the body

Processes: structures that project from the body

More about vertebrae

• Where the transverse processes extend out, muscles attach

• the spinous processes are the bumps you feel down your back

• the body and arch form a vertebral foramen

• the vertebral foramen of many vertebrae form the vertebral canal

• the vertebral canal holds the spine’

• the intervertebral foramen allow the nerve bundles to come out

Intervertebral disks

• located between the vertebra

• made of fibrocartilage

• provide support, cushioning, and precent vertebral bodies from rubbing together

• 90% water in young people

• Dehydrate and compress with afe

• Made of

  • Annulus fibrosis - fibrous ring on the external portion of the disk

    • weakens with age and can allow herniations

  • Nucleus pulposus - the internal gelatinous pulp of the disk

Intervertebral disks: herniated or ruptured disks

• result from the breakage or ballooning of the annulus fibrosis

• can have a partial or complete release of the nucleus pulposus

• can compress or push on spinal cord or nerve bundles

  • can negatively impact function of nerve

  • can cause pain

• most common in the lumbar region, but also prevalent in the cervical spine

Cervical Vertebrae

• C1-C7

• Small bodies

• Spinous process is split

  • Transverse foramen present to allow major arteries to go the head

Cervical Vertebrae: C1 - Atlas

• Holds up the head

• No body

• No spinous process

• Large superior articular processes that join the occipital condyle of the skull

• allows the yes head motion

Cervical Vertebrae: C2- Axis

• allows the head to rotate

• allows the no motion at the articulation of C1 and C2

• Dens acts as the pivot point

Cervical Vertebrae: C3-C7

• Smallest and lightest vertebrae

• Shirt spinous processes

Thoracic Vertebrae

• T1-T12

• the “typical” vertebrae

• have long, thin spinous processes and hook down

  • have articulations with the ribs of the rib cage

• Long transverse processes

• body is heart-shaped

• larger than cervical vertebrae

Lumbar Vertebrae

• L1-L5

• Large thick bodies; block-like

• Heavy rectangular transverse and spinous processes

• Limited rotation

• Sturdiest vertebrae due to heavy stress

Sacrum

• The sacrum is formed by the fusion of five bones

• The sacrum forms the posterior wall of the pelvis and it articulates laterally with the hip bones to form the sacroiliac joints

• fused spinous processes make the median sacral crest

Coccyx

• The tailbone

• is formed from the fusion of three to five small vertebrae

• no foramen or processes

Thorax (thoracic cage)

• Also called the rib cage

• protects the vital organs underneath

• forms a semi-rigid chamber than can increase and decrease in volume for respiration

• It is made up of three parts

  • Sternum

  • Ribs (with associated cartilage)

  • Thoracic vertebrae

Sternum

• also called the breastbone

• The sternum is attached to the first seven pairs of ribs

• consists of three bones that look like a sword

• Manubrium - the sword handle

  • the jugular notch on the superior margin go the manubrium can be felt at the base of the neck

  • the first rib and collarbones articulate to the manubrium

  • The sternal angle is where the manubrium and body come together and where the 2nd rib’s cartilage attaches

• Body (gladiolus) - the sword blade

• Xiphoid process - the sword tip

  • No ribs connect here

The ribs

• There are 12 pairs of ribs

• The first seven are the true ribs

  • because they attach directly to the sternum via their cartilage

  • ribs #1 -7, superior to inferior

• The remaining ribs (#8-12) are referred to as false ribs

  • because they either attach indirectly to the sternum or are not attached to the sternum at all

  • the last two pairs of false ribs are called the floating ribs (do not connect to the sternum at all)

• The intercostal spaces (spaces between the ribs) are filled with the intercostal muscles that aid in breathing

Appendicular Skeleton

The appendicular skeleton is divided into three parts:

• the upper limbs

• the Lower limbs

• the girdles ( belt or cone where limbs attach)

  • pectoral

  • pelvic

Pectoral girdle

• the upper limbs are very mobile and can perform many functions and movements

• the limbs are loosely attached by muscles to the girdle to allow for freedom and variety of movement

• Also called the shoulder girdle

• made up of two bones that attach to the upper limb

  • Scapula (shoulder blade)

  • Clavicle (collar bone)

Pectoral Girdle: Scapula

• Thin, flat bone with a triangular shape

• The acromion process is the tip of the shoulder

  • it protects the shoulder joint

  • it is an attachment site for the clavicle

  • it is also an attachment site for the shoulder muscles

• The scapular spine extends from the acromion process along the back of the scapula

• The glenoid cavity articulates with the upper arm bone

Pectoral Girdle: Clavicle

• A long bone

• S-shaped curve

• Lateral end articulates with the acromoin process

• medial end articulates with the manubrium

• this is how the axial skeleton connects with the pectoral girdle

• holds the limb away from the body so it can have a large range of motion

Upper Limb: Arm

• from the shoulder to the elbow

• comprised of only one bone - the humerus

  • Proximally

    • head articulates with the glenoid process of scapula

    • no true neck, so a “surgical neck” is defined

    • the various tubercles are sites fir biceps and deltoid muscles attachment

  • Distally

    • where humerus meets with forearm bones

    • Capitulum - anterior, rounded, articulates with radius of the forearm

    • Trochlea - distal, medial, articulates with forearm bones

    • Medial and lateral epicondyles are where forearm muscles attach

Upper Limb: forearm

• Made up of two bones

  • Ulna - medial (little finger side; for anatomical position

  • Radius - lateral (thumb side; from anatomical position

Upper Limb: Forearm: Ulna

• Medial from anatomic position

  • Proximally

    • Trochlear notch - a c-shpaed articulation of the trochlea of the humerus

    • held to the humerus by the olecranon (the elbow-posterior) and coronoid processes (anterior)

  • Distally

    • Small head that articulates with radius and the wrist

    • Styloid process where the wrist ligaments attach

Upper Limb: Forearm: Radius

• lateral from anatomical position

• Proximally

  • head is concave and articulates with the capitulum of the humerus

  • articulates with the ulna at the radial notch of the ulna and allows for forearm rotation

• Distally

  • articulates with the carpals and the ulna

Upper Limb - Wrist and Hand

the wrist and hand are made up of three parts

• The carpals or wrist bones

• the metacarpals or hand bones

• the phalanges/digits/finger bones

Upper Limb: Wrist

• the wrist is the short portion between the forearm and hand

• There are 8 carpal bones

  • 2 rows

  • 4 bones each

• Proximal Row

  • Lateral (thumb) to medial (little finger)

  • Scaphoid → Lunate → Triquetrum → Pisiform

• Distal row

  • Medial to lateral

  • Hamate → Capitate → Trapezoid → Trapezium

So Long Top Part Here Comes The Thumb

Upper Limb: Hand

• 5 metacarpal bones

• attach to the carpals of the wrist

• numbered laterally (from the thumb) 1-5

• The distal ends of the metacarpals make the knuckles

Upper Limb: Digits

• 1 thumb + 4 fingers

• Phalanges - the small bones that make up the digits

  • all the finger have three phalanges - proximal, middle and distal

  • the thumb only has two phalanges - proximal and distal

Pelvic Girdle and lower limb

• the longer limb support the body and allow for movement

• the pattern of the pelvic girdle and lower limb is similar to that pectoral girdle and upper lumbar

• the pelvic girdle and lower limb are attached more firmly than the pectoral girdle and upper limb. this results in less mobility in the lower limbs compared to the upper limbs

• bones of the lower limbs are thicker and heavier than the upper limbs

Pelvic girdle

• a place for attachment for the lower limbs

• supports the body weight

• protects the internal organs

• provides a birthing pathway for females

• Made of…

  • coxal bones or hip bones

    • coxal bones join anteriorly at the pubic symphysis

    • join posteriorly with the sacrum

  • Coxal bones + sacrum = pelvic girdle

  • Pelvic girdle + coccyx = pelvis

Pelvic Girdle

• Coxal bone has 3 parts:

  • llium

  • Ischium

  • Public Bone/ pubis

• these join at the center of the acetabulum

Lower limb

• the lower limb is made up of of the

  • thigh

  • leg

  • foot

Lower Limb: Thigh

• proximal, long bone

• made of a single bone - femur

• has a prominent, well-rounded head

• articulates with the acetabulum of the coxal bones

• lateral and medial condyles articulate with the tibia

• epicondyles are important for ligament attachment and trochanters are important for muscle attachment

Lower Limb: Leg

• Knee to ankle

• 2 bones: tibia and fibula

Lower Limb: Leg: Tibia

medial, shin bine, larger and weight-bearing bone

• has a tibial tuberosity that can be felt on the front of the shin

• has a tibial crest you can feel on the top of the shin

• the medial malleolus at its distal end makes the inner ankle bone

Lower Limb: Leg: Fibula

lateral, smaller bone, non-weight-bearing bone

• does not articulate to the femur

• head articulates with the tibia

• the lateral malleolus on the distal end makes the lateral wall of the ankle

• weakest leg bone

Lower Limb: Foot

• Made of:

  • 7 tarsal bones

  • 5 metatarsals (top of foot)

  • 5 phalanges (toes)

• 7 tarsal bones are in 2 rows

  • Proximal “row”

    • 3 bones - Navicular, Talus, Calcaneous

    • “No Thanks Cow” (distal → proximal → superior view)

    • The calcareous, or HEEl, is the largest and strongest bone in the foot; it is inferior to the talus and supports it

    • the talus, or ankle bone, articulates with the tibia and fibula

  • Distal Row

    • four bones - medial cuneiform, intermediate cuneiform, lateral cuneiform, and the cuboid

    • “MILC” (medial → lateral; superior view)

Lower Limb: Foot: Metatarsals and Phalanges

• Are like the metacarpals and phalanges of the hand

• the “big toe” (hallux) is the thumb (pollen)

• the ball of the foot is the junction of the metatarsals and phalanges

• the metatarsals are numbered 1-5 from the medial big toe to the lateral little toe (like the metacarpals)

• the phalanges all have a proximal, intermediate/middle and distal bone, except the big toe that only has a proximal and distal bone