1. Unit - 7- Skeleton anatomy by Thiru murugan

The Skeletal System
By Thiru murugan. M
1st Semester Anatomy

• Unit – 7: Anatomy - The Musculoskeletal
system:
• The Skeletal system
• Anatomical positions
• Bones: types, structure, growth and ossification
• Axial and appendicular skeleton
• Joints: classification, major joints and structure
• Application and implications in nursing

• The Muscular system:
• Types and structure of muscles
• Muscle groups: muscles of the head, neck, thorax,
abdomen, pelvis, upper limb and lower limbs
• Principal muscles: deltoid, biceps, triceps,
respiratory, abdominal, pelvic floor muscles,
gluteal muscles and vastus lateralis
• Major muscles involved in nursing procedures

• Skeletal system:
• The human skeletal system consists of all of the bones,
cartilage, tendons, and ligaments in the body
• It Provide framework of the body.
• Altogether, the skeleton makes up about 20% of a
person's body weight. An adult's skeleton contains 206
bones.
• It providing support and protection for the internal
organs
• The skeletal system also provides attachment points for
muscles to allow movements at the joints.

Components of skeletal system:
• Cartilage: This smooth and flexible
substance covers the tips of your bones
where they meet. It enables bones to move
without friction (rubbing against each
other).
• Functions of Cartilage:
• Model for bone growth in embryo & fetus
• Provides a smooth cushion between
adjacent bones
• Provides firm flexible support (nose, ears,
ribs & trachea)
• Excellent shock absorber

• Ligaments: Bands of strong
connective tissue called ligaments
hold bones together.
• Functions of Ligaments:
• Attach bones to bones
• Provide stability
Ligament

• Tendons: Tendons are bands
of tissue that connect the ends
of a muscle to your bone.
• Functions of Tendons:
• Attach muscles to bones
• Anchors muscle to bone for
movement
• Joints: A joint is where two or
more bones in the body come
together.

• Anatomical position:
• Anatomical position, or standard
anatomical position, refers to the
positioning of the body when it is
standing upright and facing
forward with each arm hanging
on either side of the body, and
the palms facing forward. The
legs are parallel, with feet flat on
the floor and facing forward.

• Bones – types, structure, growth and ossification:
• Bones:
• Bone are specialized forms of strong connective tissue that
forms the skeleton of the body.
• It is composed of calcium phosphate and calcium carbonate.
• It also serves as a storage area for calcium, playing a large
role in calcium balance in the blood
• The smallest bone in the human body is called the stirrup or
stapes bone, located deep inside the ear & The longest bone in
the human is called the femur.

• Classification or types of bones:
• Bones are divided into 5 types.
1. Long Bone
2. Short Bone
3. Flat Bone
4. Irregular Bone
5. Sesamoid Bone

1. Long Bone:
• A long bone is one that is cylindrical in shape, being longer than it is
wide.
• Shape of a bone, not its size.
• Long bones are found in: Arms (humerus, ulna, radius) & fingers
(metacarpals, phalanges) and also Legs (femur, tibia, fibula), and toes
(metatarsals, phalanges).
• Long bones function as levers; they move when muscles contract.
2. Short bones:
• cube-like in shape, equal in length, width, and thickness.
• Example: Carpals of the wrists & Tarsals of the ankles.
• Short bones provide stability and support as well as some limited motion.

3. Flat Bones:
• The term “flat bone” is somewhat of a misnomer because, although a
flat bone is typically thin, it is also often curved.
• Examples include the cranial bones, the scapulae, the sternum, and the
ribs.
• Flat bones serve as points of attachment for muscles and often protect
internal organs.
4. Irregular Bones:
• An irregular bone is one that does not have any easily characterized
shape and therefore does not fit any other classification.
• These bones tend to have more complex shapes, like the vertebrae,
Many facial bones, particularly the ones containing sinuses.

5. Sesamoid Bones:
• A sesamoid bone is a small, round bone that, as the name suggests, is
shaped like a sesame seed.
• These bones form in tendons where a great deal of pressure is
generated in a joint.
• The sesamoid bones protect tendons by helping them overcome
compressive forces.
• Sesamoid bones vary in number and placement from person to person
but are typically found in tendons associated with the feet, hands, and
knees.
• The patellae (singular = patella) are the only sesamoid bones found in
common with every person.

• Structure of bone:
• The basic structure of bones is bone matrix, which makes up the
underlying rigid framework of bones, composed of both compact
bone and spongy bone.
• The bone matrix consists of tough protein fibers, mainly collagen,
that become hard and rigid due to mineralization with calcium
crystals.
• Bone matrix is crossed by blood vessels and nerves and also contains
specialized bone cells that are actively involved in metabolic
processes.
• Bone matrix provides bones with their basic structure. Notice the
spongy bone in the middle, and the compact bone towards the outer
region. The osteon is the functional unit of compact bone.

• The microscopic structural unit of compact bone is called
an osteon, or Haversian system.
• Each osteon is composed of concentric rings of calcified
matrix called lamellae (singular = lamella).
• Running down the center of each osteon is the central
canal, or Haversian canal, which contains blood vessels,
nerves, and lymphatic vessels.
• These vessels and nerves branch off at right angles
through a perforating canal, also known as Volkmann’s
canals, to extend to the periosteum and endosteum

• Bone Cells: Bones are made of four main kinds of cells:
1. Osteoblasts
2. Osteocytes
3. Osteoclasts
4. Lining cells.
• Osteoblasts: are responsible for making new bone as your body
grows.
• They also rebuild existing bones when they are broken. To make new
bone, many osteoblasts come together in one spot then begin making a
flexible material called osteoid.
• Minerals are then added to osteoid, making it strong and hard. When
osteoblasts are finished making bone, they become either lining cells or
osteocytes.

• Osteocytes: Mature bone cells are called osteocytes
• Osteoclasts: Bone-destroying cells & Break down bone
matrix for remodelling and release of calcium
• Lining cells: are very flat bone cells.
• These cover the outside surface of all bones and are also
formed from osteoblasts that have finished creating bone
material.
• These cells play an important role in controlling the
movement of molecules in and out of the bone

• Bone Tissues:
• Bones consist of different types of tissue,
including periosteum, compact bone, spongy
bone, and bone marrow.
1.Periosteum.
2.Cortical, or Compact Bone.
3.Cancellous, or Spongy Bone.
4.Bone Marrow.

1.Periosteum: The periosteum is a tough membrane that covers
and protects the outside of the bone.
2.Compact bone: Below the periosteum, compact bone is white,
hard, and smooth. It provides structural support and protection.
3.Spongy bone: The core, inner layer of the bone is softer than
compact bone. It has small holes called pores to store marrow
4. Bone Marrow: The inside bones are filled with a soft tissue
called marrow.
• There are 2 types of bone marrow: red and yellow.
• Red bone marrow is where all new RBC, WBC, and platelets
are produced.

• Red bone marrow is found in the center of flat bones
such as your scapula and ribs.
• Yellow marrow is made mostly of fat and is found in
the hollow centers of long bones, such as the femur
bones.
• Yellow bone marrow does not make blood cells & helps
to store fat.
• Both yellow and red bone marrow have many small and
large blood vessels and veins running through them to
let nutrients and waste in and out of the bone.

• At birth, all the marrow in body
was red marrow, which made
lots and lots of blood cells to
help the body to grow bigger.
• As you got older, more and
more of the red marrow was
replaced with yellow marrow.
• The bone marrow of full grown
adults is about half red and half
yellow.

Structure of a Long Bone:
• Diaphysis: Shaft & Composed of compact bone
• Epiphysis: Ends of the bone & Composed mostly
of spongy bone
• Periosteum: Outside covering of the diaphysis &
Fibrous connective tissue membrane
• Endosteum: inner layer of bone
• Arteries: Supply bone cells with nutrients

• Articular cartilage: Covers
the external surface of the
epiphyses
• Made of hyaline cartilage
• Medullary cavity: Cavity of
the shaft
• Contains yellow marrow
(mostly fat)
• Contains red marrow (for
blood cell formation)

Growth and Ossification of bones:
• Ossification, or osteogenesis, is the process of bone formation.
• Parts of the skeleton form during the first few weeks
after conception.
• By the end of the 8th week after conception, the skeletal pattern is
formed in cartilage and membranes and ossification begins.
• Bone development continues throughout adulthood.
• Even after adult, bone development continues for repair of
fractures and for remodeling to meet changing lifestyles.
• Osteoblasts, osteocytes & osteoclasts are the
3 cells types involved in the development, growth & remodeling
of bones.

• Stages of bone growth:
1. Initial Bone Formation: The formation of bone
during the fetal stage of development occurs by
2 processes: Intramembranous ossification &
endochondral ossification.
2. Intramembranous ossification is the process of
bone development from fibrous membranes. It is
involved in the formation of the flat bones of the
skull, the mandible, and the clavicles.

The steps in Intramembranous ossification are:
• Development of ossification center
• Calcification
• Formation of trabeculae
• Development of periosteum
(At the ends of long bones is full of holes that
are connected to each other by thin rods and
plates of bone tissue known as trabeculae.)

3. Endochondral ossification
• It is the process of bone development from hyaline
cartilage.
• All of the bones of the body (except for the flat bones)
are formed through endochondral ossification
• Endochondral ossification begins with points in the
cartilage called “primary ossification centers.”
• They mostly appear during fetal development, though a
few short bones begin their primary ossification after
birth.

• These cartilage points are responsible for the formation of the
diaphyses of long bones, short bones, and certain parts of
irregular bones.
• Secondary ossification occurs after birth and forms the
epiphyses of long bones and the extremities of irregular and flat
bones.
• The diaphysis and both epiphyses of a long bone are separated
by a growing zone of cartilage (the epiphyseal plate).
• When the child reaches skeletal maturity (18 to 25 years of
age), all cartilage is replaced by bone, fusing the diaphysis and
both epiphyses together (epiphyseal closure).

4. Remodeling:
• Even after skeletal maturity has been attained, bone is constantly being
resorbed and replaced with new bone in a process called bone remodeling, it
occurs throughout a person’s life long beyond the initial development of bone.
• Bone remodeling is carried out through the work of osteoclasts, which are
bone cells that resorb bone and dissolve its minerals.
• Osteoblasts and osteoclasts are referred to as a bone remodeling unit.
• The purpose of remodeling is to regulate calcium homeostasis & repair
micro-damage from everyday stress, as well as to shape the skeleton during
growth.
• Bone repair:
• Bone repair (or healing) is the process in which a bone repairs itself
following a bone fracture
• Minerals involved in ossification include: calcium, vitamin D, potassium,
phosphorus, magnesium, iron, sodium & chlorine

• Axial and appendicular skeleton:
• Skeletal system divided into 2 parts, the axial skeleton & the
appendicular skeleton.
• Bones of the axial skeleton: It’s made up of the bones that form the
vertical axis of the body.
• It protect internal organs that includes skull (22), vertebral
column (26), thoracic cage (25), ear bones (6) & Hyoid (1) =80)
• Bones of the appendicular skeleton consists of the bones that
make up the arms and legs, as well as the bones that attach them to
the axial skeleton.
• It facilitate movement with total 126 (64 in the upper & 62 in the
lower) appendicular skeleton.

Bones of the axial skeleton:
Skull bones:
• The adult skull comprises 22
bones. These bones can be
further classified by location:
• Cranial bones: The
8 cranial bones form the
bulk of your skull.
• Facial bones: There are 14
facial bones. They’re found
on the front of the skull and
make up the face.

• Cranial bones: (8 cranial bones)
• The cranium (also known as the neurocranium) is formed by
the superior aspect of the skull. It encloses and protects the
brain, meninges, and cerebral vasculature.
• Anatomically, the cranium can be subdivided into a roof and
a base:
• Cranial roof - comprised of the frontal, occipital and two
parietal bones. It is also known as the calvarium.
• Cranial base - comprised of six bones: frontal, sphenoid,
ethmoid, occipital, parietal and temporal. These bones articulate
with the 1st cervical vertebra (atlas), the facial bones, and the
mandible (jaw).

• The joint between the skull
bones are called sutures they
are:
• Coronal suture: fuses the
frontal bone with the two
parietal bones.
• Sagittal suture: fuses both
parietal bones to each other.
• Lambdoid suture: fuses the
occipital bone to the two
parietal bones.

• Fontanelle:
• In neonates, the incompletely
fused suture joints give rise to
membranous gaps between the
bones, known as fontanelles. The
2 major fontanelles are:
• Frontal fontanelle (bregma):
located at the junction of the
coronal & sagittal sutures
• Occipital fontanelle (lamnda):
located at the junction of the
sagittal & lambdoid sutures

• Frontal bone: This is the flat bone that makes up forehead. It also
forms the upper portion of eye sockets.
• Parietal bones: This a pair of flat bones located on either side of
head, behind the frontal bone.
• Temporal bones: This is a pair of irregular bones located under
each of the parietal bones.
• Occipital bone: This is a flat bone located in the very back of skull.
It has an opening that allows the spinal cord to connect to brain.
• Sphenoid bone: This is an irregular bone that sits below the frontal
bone. It forms a large part of the base of skull.
• Ethmoid bone: This is an irregular bone located in front of the
sphenoid bone. It makes up part of nasal cavity.

• Facial bones: There are 14 facial bones. The facial
skeleton (also known as the viscerocranium) supports the soft
tissues of the face, which fuse to house the orbits of the eyes,
the nasal and oral cavities, and the sinuses.
• The frontal bone, typically a bone of the calvaria, is sometimes
included as part of the facial skeleton.
• The facial bones are:
• Zygomatic (2): forms the cheek bones of the face and
articulates with the frontal, sphenoid, temporal and maxilla
bones.
• Lacrimal (2): the smallest bones of the face. They form part of
the medial wall of the orbit.

• Nasal (2): slender bones that are located at the bridge of the
nose.
• Inferior nasal conchae (2): located within the nasal cavity,
these bones increase the surface area of the nasal cavity, thus
increasing the amount of inspired air that can come into contact
with the cavity walls.
• Palatine (2): situated at the rear of oral cavity and forms part of
the hard palate.
• Maxilla (2): comprises part of the upper jaw and hard palate.
• Vomer: forms the posterior aspect of the nasal septum.
• Mandible (jaw): articulates with the base of the cranium with
temporal bone called temporomandibular joint (TMJ).

• Function of the skull:
• Along with the surrounded meninges, is to provide
protection and structure.
• Protection to the brain (cerebellum, cerebrum,
brainstem) and orbits of the eyes.
• Structurally it provides an anchor for tendons and
muscular attachments of the muscles of the scalp and
face.
• The skull also protects various nerves and vessels that
feed and innervate the brain, facial muscles & skin.

Vertebral column:
• The vertebral column encloses the spinal cord and the fluid
surrounding the spinal cord. Also called backbone, spinal
column, and spine.
• Each vertebra is separated by a disc called intervertebral disc
• The vertebrae surround and protect the spinal cord. The spinal
cord is divided into segments, each containing a pair of spinal
nerves that send messages between the brain and the rest of the
body.
• Many spinal nerves extend beyond the conus medullaris (the
end of the spinal cord) to form a bundle of nerves called the
cauda equina.

• The vertebral column is made up 26
• Cervical vertebrae: These 7 bones
are found in the head and neck.
• Thoracic vertebrae: These 12 bones
are found in the upper back.
• Lumbar vertebrae: These 5 bones
are found in the lower back.
• The sacrum (5) and coccyx (4) are
both made up of several fused
vertebrae. They help support the
weight of the body while sitting.

• Parts of the vertebrae:
• The vertebrae of the cervical, thoracic, and lumbar
spines are independent bones and generally quite
similar.
• The vertebrae of the sacrum & coccyx are usually fused
and unable to move independently.
• 2 special vertebrae are the atlas (cervical 1) and axis
(cervical 2), on which the head rests.
• A typical vertebra consists of 2 parts: the vertebral
body and the vertebral arch.

• Vertebral body: Vertebral body is the thick oval segment of
bone forming the front of the vertebra also called the
centrum. The cavity of the vertebral body consists of
cancellous bone tissue and is encircled by a protective layer of
compact bone.
• The vertebral arch is posterior, meaning it faces the back of a
person.
• Together, these enclose the vertebral foramen, which contains
the spinal cord.
• Because the spinal cord ends in the lumbar spine, and the
sacrum and coccyx are fused, they do not contain a central
foramen.

• The vertebral arch is formed by a pair of pedicles & a pair of laminae,
and supports 7 processes (4 articular, 2 transverse, and 1 spinous)
• 4 articular process: 2 articular process for above vertebrae & 2 articular
process for ribs.
• 2 transverse processes and 1spinous process are posterior to (behind)
the vertebral body.
• The spinous process comes out the back, The spinous processes of the
cervical and lumbar regions can be felt through the skin.
• 1 transverse process comes out the left, and 1 on the right.
• Above & below each vertebra are joints called facet joints. These
restrict the range of movement possible
• In between each pair of vertebrae are 2 small holes called intervertebral
foramina. The spinal nerves leave the spinal cord through these holes.

• Cervical spine:
• The cervical spine located in the neck area, consists of seven bones
(C1 to C7)
• The first two cervical spine are unique in shape and function.
• first vertebra (C1), also called the atlas, The atlas holds head
upright.
• The second vertebra (C2), also called the axis, allows the atlas to
rotation of head.
• Functions:
• Protecting spinal cord.
• Supporting head and allowing movement.
• Providing a safe passageway for vertebral arteries.

• Nerves in the cervical spine
• Eight pairs of spinal nerves exit through cervical spine.
• Cervical nerves C1, C2 and C3 control forward, backward and side head and neck
movements. The C2 nerve provides sensation to the upper area of head; C3 gives
sensation to the side of face and back of head.
• Cervical nerve 4 controls upward shoulder motion and is one of the nerves that
controls diaphragm. C4 provides sensation for parts of neck, shoulders and upper
arms.
• Cervical nerve 5 controls the deltoid muscles. C5 provides sensation to the upper
part of your upper arm down to your elbow.
• Cervical nerve 6 controls the muscles of wrist and is involved in the control of
biceps. C6 provides sensation to the thumb side of forearm and hand.
• Cervical nerve 7 controls triceps and wrist muscles. C7 provides sensation to the
back of arm into middle finger.
• Cervical nerve 8 controls hands and gives sensation to the pinky side of hand and
forearm

• Thoracic spine
• Thoracic spine is the middle & the longest part of spine.
• It starts at the base of neck and ends at the bottom of ribs.
• It consists of 12 vertebrae - T1 to T12.
• Thoracic spine is especially rigid and stable
• Thoracic spine nerves include:
• T1 and T2 nerves: these nerves go into the top of chest and into arms
and hands.
• T3 through T5 nerves: these nerves go into chest wall. Together, these
nerves help to control rib cage, lungs and diaphragm for breathing.
• T6 through T12 nerves: these nerves go into abdominal and back
muscles. It help with balance and posture

• Function of the thoracic spine:
• Protecting spinal cord and branching spinal nerves
• Providing attachments for ribs
• Supporting chest and abdomen
• Allowing movement of body

• Lumbar spine:
• Lumbar spine consists of the five bones (vertebra) in lower back.
• Lumbar vertebrae, known as L1 to L5, are the largest of entire
spine.
• Lumbar spine is located below 12 chest (thoracic) vertebra and
above the five fused sacrum bone.
• Functions
• Supports upper body, distributes body weight.
• Movements of body.
• Protects spinal cord and cauda equina.
• Controls leg movement.
• Site for lumbar puncture ( for anesthesia & collecting CSF)

• Nerves of the lumbar spine: five pairs of lumbar spinal nerves, one that
branches off from the right and left sides of L1 to L5. these nerves that
control pain signals and the movements of lower limbs.
• L1 spinal nerve provides sensation to groin and genital area and helps
move your hip muscles.
• L2, L3 and L4 spinal nerves provide sensation to the front part of thigh
and inner side of lower leg. These nerves also control hip and knee
muscle movements.
• L5 spinal nerve provides sensation to the outer side of lower leg, the
upper part of foot and the space between first and second toe. This nerve
also controls hip, knee, foot and toe movements.
• The sciatic nerve consists of the L4 and L5 nerves plus other sacral
nerves.

• Sacrum:
• The sacrum - terminal part of the vertebral canal, where it forms the
posterior part of the pelvis.
• It is thick, supporting and transmitting the weight of the body.
• The sacrum is fusion of the 5 sacral vertebrae.
• The bone consists of a base, apex and four surfaces:
• Base: articulates superiorly with the 5th lumbar vertebra
• Apex: attach the coccyx inferiorly.
• Ala or wing: located laterally on the sacrum. Each articulates with the
ilium
• Anterior and posterior surfaces: provide attachment to pelvic
ligaments and muscles.

• Coccyx: The coccyx (also known as the tailbone) is the terminal
part of the vertebral column. It is comprised of 4 vertebrae (fused)
• Parts: The coccyx consists of an apex, base, anterior surface,
posterior surface and two lateral surfaces.
• The base is located most superiorly - articulation with the sacrum.
• The apex is situated inferiorly, at the terminus of the vertebral
column.
• The lateral surfaces of the coccyx are marked by a small transverse
process, which projects from Co1.
• The coccygeal cornua of Co1 are the largest of the small articular
processes of the coccygeal vertebrae.
• They project upwards to articulate with the sacral cornua.

• Thoracic cage:
• The thoracic cage (rib cage) is the skeleton of the thoracic
wall.
• It is formed by the 12 thoracic vertebrae, 12 pairs of ribs
and associated costal cartilages and the sternum.
• The thoracic cage - functions to support thorax and protect the
vital structures within it (e.g. heart, lungs, aorta, etc).
• Its rigid structure allows it to be an attachment point for many
muscles of the upper body and to support the weight of
the upper limbs.
• The thoracic cage also facilitates the act of breathing.

• Ribs:
• The ribs are the bony framework of the thoracic cavity.
• The ribs form the main structure of the thoracic cage protecting the
thoracic organs, however their main function is to aid respiration.
• There are 12 pairs of ribs.
• Each rib articulates posteriorly with thoracic vertebrae by
the costovertebral joint.
• According to their attachment to the sternum, the ribs are classified
into 3 groups: true, false, and floating ribs.
• The true ribs - directly articulate with the sternum with their
costal cartilages - ribs 1-7. They articulate with the sternum by the
sternocostal joints.

• The false ribs (8,9,10) are the ribs that indirectly articulate
with the sternum, as their costal cartilages connect with the
seventh costal cartilage by the costochondral joint.
• The floating ribs (11,12) do not articulate with the sternum at
all (distal two ribs).
• Anatomical components of ribs:
• Head with articular facets
• Neck
• Tubercle
• Shaft
• Costal groove

• Sternum: The sternum (or breastbone) is a flat bone located at
the anterior aspect of the thorax. It lies in the midline of the chest and has a
‘T’ shape.
• Parts of the Sternum: 3 parts: the manubrium , body & & xiphoid
process.
• Manubrium: most upper part of the sternum.
• The superior aspect of the manubrium is concave, producing a depression
known as the jugular notch, Either side of the jugular notch, there is a
large fossa lined with cartilage called Clavicular notch, articulate with the
medial ends of the clavicles, forming the sternoclavicular joints
• On the lateral edges of the manubrium, there is a facet, for articulation
with the costal cartilage of the 1st & 2nd ribs.
• Inferiorly, the manubrium articulates with the body of the sternum,
forming the sternal angle (Angle of louis).

• Body: The body is flat and elongated & largest part of the sternum. It
articulates with the manubrium superiorly (manubriosternal joint) &
the xiphoid process inferiorly (xiphisternal joint).
• The lateral edges of the body are marked by numerous articular facets.
These articular facets articulate with the costal cartilages of ribs 3 - 6.
• There are smaller facets for articulation with parts of the 2nd & 7th
ribs
• Xiphoid Process:
• The xiphoid process is the most inferior and smallest part of the
sternum.
• The xiphoid process is largely cartilaginous in structure.
• In some individuals, the xiphoid process articulates with part of the
costal cartilage of the 7th rib.

• Function of the thoracic cage:
• The main function of the thoracic cage is to support
thorax and protect the vital structures within it
(e.g. heart, lungs, aorta, etc).
• In addition, the rigid structure of the cage allows it
to be an attachment point for many muscles of the
upper body and to support the weight of the upper
limbs.
• The thoracic cage also facilitates the act
of breathing

Ear bones (6):
• Bones of the inner ear (or)
auditory ossicles, Inside the
temporal bone are the 3
smallest bones of the body:
1. Malleus (one in each ear)
2. Incus (one in each ear)
3. Stapes or stirrup (one in
each ear - this is the
smallest bone in the body)
• These three bones articulate with
each other and transfer
vibrations from the tympanic
membrane to the inner ear.

Hyoid (1): (The laryngeal skeleton)
• The hyoid bone is a horseshoe shaped
bone that sits at the front of neck.
• Muscles and ligaments hold it in place
between jaw bone and thyroid. hyoid
bone helps you breathe, speak &
swallow.
• It is located between the trachea & the
root of the tongue.
• The movements of the hyoid both open
and close the glottis
• Regulate the degree of tension of the
vocal folds, when air is forced through
them produce vocal sounds.

• Appendicular skeleton:
• There are a total of 126 bones in the appendicular skeleton.
• It consists of the bones that make up the arms and legs, as well
as the bones that attach them to the axial skeleton.
• Bones of the appendicular skeleton facilitate movements
• It consist of:
• Shoulder girdle (4)
• Upper limb (Right: 30 + left: 30 = 60)
• Pelvic girdle (2)
• Lower limb (Right – 30 + left - 30 = 60)
Total: 126
bones

• Shoulder girdle (or) Pectoral girdle:
• The pectoral girdle or shoulder girdle is where the arms attach to the
axial skeleton. It consist clavicle & scapula
• Clavicle - 2 (collarbone):
• The clavicle is located between the ribcage (sternum) and the
shoulder blade (scapula). It is the bone that connects the arm to the
body.
• Attaches medially to manubrium of sternum & laterally to scapula,
prevents shoulder dislocation.
• The clavicle is a slender bone with an ‘S’ shape. It can be divided into
a sternal end, a shaft and an acromial end.
• Sternal (medial) End: It contains a large facet – for articulation with
the manubrium of the sternum at the sternoclavicular joint.

• Shaft: The shaft of the clavicle acts a point of origin and attachment for
several muscles - deltoid, trapezius, subclavius, pectoralis major,
sternocleidomastoid and sternohyoid.
• Acromial (lateral) End: it has a small facet for articulation with the
acromion of the scapula at the acromioclavicular joint. It also serves as
an attachment point for two ligaments: Conoid tubercle – attachment
point of the conoid ligament & Trapezoid line – attachment point of
the trapezoid ligament.
Clavicle: Shaft

• Clavicle Function:
• Power and stability of arm
• Motion of the shoulder girdle
• Muscle and ligaments attachment.
• Protects neurovascular structures
• Facilitates the placement of the shoulder in a more lateral
position, so the hand can be more effectively positioned
• Connects the axial skeleton with the appendicular.
• Transmission of weight of the upper limb to the axial
skeleton.

• Scapula - 2 (shoulder blade):
• The scapula is also known as the shoulder
blade.
• It is a triangular, flat bone, which serves as a
site for attachment for many muscles.
• It articulates with the humerus at the
glenohumeral joint, and with the clavicle at the
acromioclavicular joint.
• Costal surface: The costal (anterior) surface of
the scapula faces the ribcage.
• It contains a large concave depression over
most of its surface, known as the subscapular
fossa.
• A hook-like projection, which lies just
underneath the clavicle is called is the coracoid
process.

• Lateral Surface:
• The lateral surface of the scapula faces the
humerus. It is the site of the glenohumeral
joint, and of various muscle attachments. Its
important bony landmarks include:
 Glenoid fossa: It articulates with the head of
the humerus to form the glenohumeral
(shoulder) joint.
 Supraglenoid tubercle: a rough, superior to
the glenoid fossa. The place of biceps
attachment.
 Infraglenoid tubercle: inferior to the
glenoid fossa. The place of triceps
attachment.

• Posterior Surface: It faces outwards. It is
a site of origin of the shoulder muscles.
• Spine: the most prominent feature of the
posterior scapula. It runs transversely
across the scapula, dividing the surface
into two.
• Acromion: projection of the spine that
arches over the glenohumeral joint and
articulates with the clavicle at the
acromioclavicular joint.
• Infraspinous fossa: the area below the
spine of the scapula, it displays a convex
shape.
• Supraspinous fossa: the area above the
spine of the scapula, it is much smaller
than the infraspinous fossa.
Spine

• Articulations:
• The scapula has two main
articulations:
• Glenohumeral joint: between the
glenoid fossa of the scapula and the
head of the humerus.
• Acromioclavicular joint: between
the acromion of the scapula and the
clavicle.

• Functions of scapula:
• Gives attachment to muscles.
• It Has a considerable degree of movement on the
thoracic wall to enable the arm to move freely.
• The glenoid cavity forms the socket of the
shoulder joint.
• Connection with axial skeleton by clavicle.
• Important for movement.

Upper limbs:
• Each arm contains 30 bones (R – 30 + L – 30 = 60)
Bones Right Left Total
Humerus 1 1 2
Radius. 1 1 2
Ulna. 1 1 2
Carpal bones 8 8 16
Metacarpal bones 5 5 10
Phalanges 14 14 28
Grand Total 60

• Humerus (1 + 1 = 2)
• The humerus is a long bone of the upper limb, which extends from the
shoulder to the elbow.
• The proximal aspect of the humerus articulates with the glenoid fossa of the
scapula, forming the glenohumeral joint (Shoulder joint).
• Distally, at the elbow joint, the humerus articulates with the head of the
radius and trochlear notch of the ulna.
• Proximal Landmarks:
• It is marked by a head, anatomical neck, surgical neck, greater and lesser
tuberosity and intertubercular sulcus or Bicipital groove.
• Separating the two tuberosities is a deep groove, known as
the intertubercular sulcus or Bicipital groove.
• The surgical neck extends from just distal to the tuberosities to the shaft of
the humerus.

• Shaft:
• The shaft of the humerus is the site
of attachment for various muscles.
• On the lateral side of the humeral
shaft is a roughened surface where
the deltoid muscle attaches. This is
known is as the deltoid tuberosity.
• The radial (or spiral) groove is a
shallow depression that runs
diagonally down the posterior
surface of the humerus, parallel to
the deltoid tuberosity.

• Distal Region
• The lateral & medial borders of the
distal humerus form
lateral & medial epicondyles.
• Both can be palpated at the elbow.
• Posterior aspect of the bone Distally,
the trochlea is located. Lateral to
the trochlea is the capitulum, which
articulates with the radius.
• There are 3 depressions, known
coronoid, radial & olecranon fossa
Posterior Anterior

Its main
function is
to provide
support for
your shoulder
and a wide
variety of
movements
for your arm.
And also
provide
attachment for
muscles.

• Radius and ulna: The radius and ulna are long bones that make up
the forearm, extending from the elbow to the wrist.
• In the anatomical position, the radius is found in the lateral forearm
(thumb side), while the ulna is found in the medial forearm (little
finger side).
• Radius (1+1 = 2) The radius is one of two long bones of the
forearm, found on the thumb side. The radius is the lateral bone of
the forearm.
• It has three main parts:
• Proximal end
• Shaft
• Distal end.

• Proximal radius:
• The proximal end of the radius bears the head, neck and radial tuberosity.
• The head of the radius articulates with the humerus and forms elbow joint.
• Head of the radius articulate with radial notch of the ulna forming
the proximal radioulnar joint.
• Radial shaft
• The shaft of the radius is a long section of bone that continues from the neck.
• It is narrow proximally but enlarges towards the wrist (distal end).
• It has 3 borders: an anterior, posterior & interosseous border.
• The anterior border lies on the medial aspect of the bone. The posterior border
lies on the posterior aspect. The interosseous border faces the ulna &
connected to ulna through interosseous membrane, forming the middle
radioulnar joint.

• Distal radius
• The anterior surface of the distal radius
is smooth & concave.
• The medial surface bears the ulnar
notch, join with the head of the ulna to
form the distal radioulnar joint.
• The lateral surface of the distal radius is
rough and projects inferiorly as the radial
styloid process.
• The inferior surface (carpal articular
surface) bears two facets which articulate
with the scaphoid and lunate bones of
the carpus and form radiocarpal or wrist
joint.

• Ulna(1+1 = 2)
• The ulna is the second long bone of the forearm, found on the
pinky finger side
• Extends from the elbow to the wrist
• At the elbow joint, the radius and ulna articulate with the
humerus bone
• At the wrist, the radius articulates with the carpal bones called
radiocarpal joint (wrist joint) & ulna articulate with the
carpal bones called ulnocarpal joint ( not directly connected).
• Like the radius, the ulna also has three main parts: a proximal
end, shaft and a distal end.

• Proximal ulna
• The proximal ulna is a large hook-
shaped structure which articulates
with the distal humerus and the head
of the radius.
• It bears the olecranon, trochlear
notch, coronoid process, radial notch,
sublime tubercle and ulnar tuberosity.
• On the lateral aspect of the proximal
ulna and just below the trochlear
notch lies the shallow, rounded
depression called the radial notch.
The radial notch articulates with the
circumference of the radial head and
forms the proximal radioulnar
joint.

• Ulnar shaft:
• It has 3 borders (anterior, posterior and interosseous).
• Distally, the anterior border crosses to the posterior aspect of the shaft,
terminating close to the base of the styloid process.
• Similar to the radial shaft, the medially projecting interosseous border of the
ulna is attached to the radius (middle radioulnar joint)
• Distal ulna:
• The distal ulna consists of a head and an ulnar styloid process.
• The lateral surface of the head of the ulna articulates with the ulnar notch of
the distal radius to form the distal radioulnar joint.
• The inferior surface of the head of the ulna articulates with an articular disc
called the triangular fibrocartilage (TFC), which separates the ulna from the
carpal bones. The head of the ulna does not directly contribute to the
formation of the wrist joint.

• Functions of Radius & Ulna:
• Radius:
• The radius' main functions are to articulate with the ulna and
humerus at the elbow to provide supination and pronation.
• Then to articulate with the lunate and scaphoid to provide all the
movements of the wrist.
• Ulna:
• It forms the elbow joint with the humerus and also articulates with
the radius both proximally and distally. It is located in the medial
forearm when the arm is in the anatomical position. It is the larger
of the two forearm bones. Ulna assists in pronation and
supination of the forearm and hand.

• Carpals (R - 8; L - 8 = 16):
• The carpal bones (i.e. carpus) are 8 irregularly-shaped bones located in
the wrist region.
• These bones connect the distal aspects of the radius and ulna to the proximal
aspects of the metacarpal bones.
• Each carpal bone has its own unique shape and is multifaceted, meaning that
they have the ability to articulate with several surrounding bones, muscles and
ligaments of the forearm and hand.
• This way, the carpal bones provide flexibility and various types
of movements to the soft tissues of the hand.
• They also provide the majority of the skeletal framework of the wrist that
allows the passageway for the different neurovascular structures of the hand.
• Joints: radiocarpal joint (wrist joint), carpometacarpal joint, midcarpal joint,
& intercarpal joints.

• The proximal row:
1. Scaphoid
2. Lunate
3. Triquetrum
4. Pisiform
• The distal row:
1. Trapezium
2. Trapezoid
3. Capitate
4. Hamate
• The carpal bones are organized in two rows: proximal and distal.

• Functions of carpals:
• Each carpal bone is vital in forming the carpus or
wrist joint, which is the key to hand movement
• It allowing to do anything from writing, typing,
and eating to holding anything in hand.
• The carpal bones are the connection between the
forearm and hand and are the key to provides grip
strength to humans

• Metacarpal Bones (5+5 = 10):
• The metacarpal bones articulate proximally with the carpals, and distally
with the proximal phalanges.
• The metacarpals together are referred to as the “metacarpus”
• They are numbered, and each associated with a digit:
• Metacarpal 1: Thumb.
• Metacarpal 2: Index finger.
• Metacarpal 3: Middle finger.
• Each metacarpal consists of a base, shaft and a head. The medial and
lateral surfaces of the metacarpals are concave, allowing attachment of
the interossei muscles.
• Joints: metacarpophalangeal joint (MCP joint), or knuckle &
carpometacarpal joint
• Metacarpal 4: Ring finger.
• Metacarpal 5: Little finger.

• Function of the metacarpals:
• The basic function of the metacarpals is to act as the
bridge between the wrist and fingers, forming the
framework of the hand.
• Together as the carpus, it is the vital part of the
skeleton that holds together the small and large bones
in the human hand, stabilizing its dorsal and palmar
sides
• As a result, they play a crucial role in the proper
development, movement, and functioning of the hand.

Phalanges of the hand (14+14 = 28):
• The phalanges of the hand are the group of small bones that
comprise the bony core of the digits (fingers) of the hand.
• Even though the phalanges are small in size, they are classified
as long bones because of their structural characteristics.
• Each phalanx consists of a shaft, distal head and a proximal
base.
• There are 14 phalanges in each hand.
• Each of the medial four digits has 3 phalanges
(proximal, middle and distal), while the thumb has only 2
(proximal and distal).

• They are named thumb (digit 1), index finger (digit 2), middle
finger (digit 3), ring finger (digit 4) and little finger (digit 5).
• Joints:
• Metacarpophalangeal joints connect the metacarpal bones and
proximal phalanges
• Proximal interphalangeal joints connect the proximal and
middle phalanges
• Distal interphalangeal joints connect the middle and distal
phalanges
• Interphalangeal joint of thumb connect the proximal and distal
phalanges of the thumb

• Functions of Phalanges of the hand:
• The proximal phalanges are very mobile at the MCP
joints. They are mainly capable of flexion, extension,
adduction and abduction. Circumduction and rotation
are also possible, especially at the MCP joint of the
thumb.
• The middle phalanges are less mobile compared to the
proximal phalanges. They are only capable of flexion
and extension at the PIP joints.
• The distal phalanges are capable of flexion and
extension at the DIP joints.

Pelvic girdle:
• The pelvic girdle, commonly known as the hips, is where the legs attach
to the axial skeleton. It’s made up of 2 hipbones
• The hip bone (or coxae) is an irregularly shaped, bilateral bone of the
bony pelvis which is also known as the innominate bone, pelvic bone
or coxal bone.
• It consists of 3 bones: the ilium, ischium and pubis.
• The ilium is the largest and most superior part of the bone,
the ischium is located posteroinferiorly, and the pubis forms the
anterior portion of the hip bone
• Together, the ilium, pubis and ischium form a cup-shaped socket
known as the acetabulum. The head of the femur articulates with the
acetabulum to form the hip joint.

• The Ilium:
• The ilium is the widest and largest of the 3 parts of the hip bone, and is
located superiorly. The body of the ilium forms the superior part of the
acetabulum (acetabular roof). Immediately above the acetabulum, the
ilium expands to form the wing (or ala).
• The wing of the ilium has two surfaces:
• Inner surface: has a concave shape, which produces the iliac fossa
• External surface (gluteal surface): has a convex shape and provides
attachments to the gluteal muscles.
• The superior margin of the wing is thickened, forming the iliac
crest. It extends from the anterior superior iliac spine (ASIS) to the
posterior superior iliac spine (PSIS).
• On the posterior aspect of the ilium there is an greater sciatic notch.

• The Ischium:
• The ischium forms the posteroinferior part of the hip bone. It is composed of a
body, an inferior ramus and superior ramus.
• The inferior ischial ramus combines with the inferior pubic ramus forming the
ischiopubic ramus, which encloses part of the obturator foramen. The
posteroinferior aspect of the ischium forms the ischial tuberosities and when sitting,
it is these tuberosities on which our body weight falls.
• Near the junction of the superior ramus and body is a posteromedial projection of
bone; the ischial spine.
• Two important ligaments attach to the ischium:
• Sacrospinous ligament: runs from the ischial spine to the sacrum, thus creating the
greater sciatic foramen through which lower limb neurovasculature (including the
sciatic nerve) transcends.
• Sacro tuberous ligament: runs from the sacrum to the ischial tuberosity, forming the
lesser sciatic foramen.

(Latin - ramus = branch, ramus – singular & rami - plural).
The Ischium

• The Pubis: The pubis is the most anterior portion of the hip bone. It consists of a
body, superior ramus and inferior ramus (ramus = branch).
• Pubic body: located medially, it articulates with the opposite pubic body at the
pubic symphysis. Its superior aspect is marked by a rounded thickening (the pubic
crest), which extends laterally as the pubic tubercle.
• Superior pubic ramus: extends laterally from the body to form part of the
acetabulum.
• Inferior pubic ramus: projects towards the ischium.
• Together, the superior and inferior rami enclose part of the obturator
foramen through which the obturator nerve, artery and vein pass through to reach
the lower limb.
• The hip bones have three main articulations:
• Sacroiliac joint - articulation with the sacrum.
• Pubic symphysis - articulation between the left and right hip bones.
• Hip joint - articulation with the head of femur.

Lower limbs:
• Each leg is composed of 30 bones (R - 30 + L - 30 = 60)
Bones Right Left Total
Femur 1 1 2
Patella 1 1 2
Tibia 1 1 2
Fibula 1 1 2
Tarsal bones 7 7 14
Metatarsal bones 5 5 10
Phalanges 14 14 28
Grand Total 60

• Functions of Pelvic bone:
• The main functions of the pelvic girdle are to support the weight of the
upper body and aid in walking, protect the lower abdominal and pelvic
viscera and facilitate natural childbirth.
• Additionally, there are certain points on the pelvis that can be felt (palpated)
externally that clinicians use as landmarks for different clinical procedures.
• Weight-bearing and ambulation
• The pelvic girdle is a thick, robust structure that is designed to support the
weight of the upper body.
• The weight is transferred from the axial skeleton to the lower appendicular
skeleton via the pelvis while standing and walking.
• Additionally, the thick bones provide points of attachment for some of the
largest muscles within the body that are needed for adequate posture and
locomotion.

• Support
• The bony pelvis also provides anchoring points for the
smaller muscles and ligaments of the pelvic floor and the
perineum.
• Along with these structures, the bony pelvis holds in
place and protects the organs located in the pelvic cavity
including the urinary bladder, pelvic colon, reproductive
organs, and rectum.
• Also, the structures of the pelvic floor are designed to
maintain the continence of the anus and urinary tract.

• Labor and delivery
• After about nine months of growth and development in the uterus, the fetus
is ready to be born. This is an exciting, yet risky, series of events that
require very specific and coordinated actions. The details of the
mechanisms of labor require that the fetal parts are smaller than the pelvic
diameters and that the presenting fetal parts engage (enter) the pelvis
appropriately. If the fetal head is too big, the pelvic diameters are too small,
or the fetal part is not oriented appropriately (long axis of the head should
be in the transverse plane) then it may be impossible for vaginal delivery to
take place.
• Therefore, it is important for managing obstetricians to determine if the
expectant mother’s pelvis is adequate to deliver the fetus. Additionally, the
size of the fetus should also be monitored and compared with the pelvic
diameters to establish the risk of cephalopelvic disproportion at the time of
delivery.

• Femur:
• The femur is the only bone in
the thigh and the longest &
strongest bone in the body.
• It acts as the site of origin and
attachment of many muscles &
ligaments
• It can be divided into three
parts; proximal, shaft and
distal.

• Proximal: The proximal aspect of the femur articulates
with the acetabulum of the pelvis to form the hip joint.
• It consists of a head and neck, and two bony processes –
the greater and lesser trochanters.
• There are also two bony ridges connecting the two
trochanters; the intertrochanteric line anteriorly and
the trochanteric crest posteriorly.
• Head: articulates with the acetabulum of the pelvis to
form the hip joint & Neck: connects the head of the
femur with the shaft.

Anterior surface of the proximal
right femur
Posterior surface of the
right femur

• The Shaft
• On the posterior surface of the femoral shaft, there are
roughened ridges of bone, called the linea
aspera (Latin for rough line). This splits distally to
form the medial and lateral supracondylar lines. The
flat popliteal surface lies between them.
• Proximally, the medial border of the linea aspera
becomes the pectineal line. The lateral border
becomes the gluteal tuberosity, where the gluteus
maximus attaches.
• Distally, the linea aspera widens and forms the floor of
the popliteal fossa, the medial and lateral borders form
the medial and lateral supracondylar lines. The
medial supracondylar line ends at the adductor
tubercle.

• Distal: The distal end of the femur is characterized by the
presence of the medial and lateral condyles, which articulate
with the tibia and patella to form the knee joint.
• Medial and lateral condyles: rounded areas at the end of the
femur.
• The posterior and inferior surfaces articulate with the tibia and
the anterior surface articulates with the patella.
• Medial and lateral epicondyles: bony elevations on the non-
articular areas of the condyles.
• The medial epicondyle is the larger. The space between the two
condyles called Intercondylar fossa.

Anterior surface of the distal
right femur
Posterior surface of the distal
right femur

• Functions of Femur:
• Holding the weight of body when we stand and move.
• Stabilizing during movement.
• Connecting muscles, tendons and ligaments in hips and knees to the rest of your
body.
• The femur maintains the body’s weight on the leg. The bottom of the femur is
where all other leg bones are joined.
• However, the femur serves more than just physical movement. Both red and
yellow bone marrow can be found in the femur’s shaft, essential for generating
blood cells and fat storage.
• It isn’t easy to estimate blood circulation in the femur. The quantity is large
enough that dehydration or shock can be treated by injecting sufficient fluid into
the bloodstream through a needle placed in the spongy bone.
• The sturdy structure of the femur provides the strong hip and knee muscles with
many secure attachment places for walking and other thrusting activities.

• Tibia (Shinbone): The tibia is the main bone of the lower leg.
• It expands at its proximal and distal ends; articulating at
the knee and ankle joints respectively.
• The tibia is the second largest bone in the body and it is a key weight-
bearing structure.
• Proximal: The proximal tibia is widened by the medial and
lateral condyles, which aid in weight-bearing. The condyles form a flat
surface, known as the tibial plateau.
• This structure articulates with the femoral condyles to form the key
articulation of the knee joint.
• Located between the condyles is a region called the intercondylar
eminence - this projects upwards on either side as the medial and lateral
intercondylar tubercles. This area is the main site of attachment for the
ligaments of the knee joint.

• Shaft
• The shaft of the tibia is prism-shaped, with 3 borders and 3
surfaces; anterior, posterior and lateral.
• Anterior border: palpable subcutaneously down the anterior surface
of the leg as the shin. The proximal aspect of the anterior border is
marked by the tibial tuberosity; the attachment site for the patella
ligament.
• Posterior surface: marked by a ridge of bone known as soleal line.
This line is the site of origin for part of the soleus muscle
• Lateral border: also known as the interosseous border. It gives
attachment to the interosseous membrane that binds the tibia and the
fibula together.

• Distal: The distal end of the tibia widens to assist with
weight-bearing.
• The medial malleolus is a bony projection continuing
inferiorly on the medial aspect of the tibia.
• It articulates with the tarsal bones to form part of the
ankle joint.
• On the posterior surface of the tibia, there is
a groove for passage of tendon of tibialis posterior.
• Laterally is the fibular notch, where the fibula is bound
to the tibia - forming the distal tibiofibular joint.

• Fibula (Calf Bone) The fibula is the second bone in the lower leg,
• The fibula is a bone located within the lateral aspect of the leg. Its main
function is to act as an attachment for muscles, and not as a weight-
bearer.
• Articulations:
• Proximal tibiofibular joint: articulates with the lateral condyle of the
tibia.
• Distal tibiofibular joint: articulates with the fibular notch of the tibia.
• Ankle joint: articulates with the talus bone of the foot
• Proximal:
• At the proximal end, the fibula has an enlarged head, which contains a
facet for articulation with the tibia.
• On the posterior and lateral surface of the fibular neck (fibular nerve
located)

• Shaft
• The fibular shaft has 3 surfaces -
anterior, lateral and posterior. The
leg is split into 3 compartments, and
each surface faces its
respective compartment
• Distal
• Distally, the lateral surface is called
the lateral malleolus.
• The lateral malleolus is more
prominent than the medial malleolus,
and can be palpated at the ankle on the
lateral side of the leg.

• Functions of tibia & fibula
• Tibia: the tibia consist of red bone marrow, which assists in the
production of red blood cells. As a person ages, red bone marrow is
replaced with yellow bone marrow made up of fat.
• The tibia provides stability and bears weight for the lower leg. It
provides movement and facilitates walking, running, climbing,
kicking, etc.
• Fibula: Forming the structure of your calf and the outside of your
lower leg.
• Supporting your ankle.
• Supporting muscles and tendons in your leg and ankle.
• Connecting your knee ligaments to the rest of your lower body.

• Patella: The patella (kneecap) is
located at the front of the knee
joint, within the patellofemoral
groove of the femur.
• Its superior aspect is attached to
the quadriceps tendon and
inferior aspect to the patellar
ligament.
• It protects and covers the knee
• It is classified as a sesamoid type
bone & largest sesamoid bone in
the body.

• Bony Landmarks of patella:
• It has a triangular shape, with anterior and
posterior surfaces.
• Anterior surface: The apex of the patella
is situated inferiorly and is connected to the
tibial tuberosity by the patellar ligament.
The base forms the superior aspect of the
bone and provides the attachment area for
the quadriceps tendon.
• The posterior surface of the patella
articulates with the femur, and is marked
by two facets:
• Medial facet: articulates with the medial
condyle of the femur.
• Lateral facet: articulates with the lateral
condyle of the femur.

• Functions of patella:
• The primary function of the patella is during knee
extension.
• The fact that the patella sits atop the anterior surface of
the femoral condyles, increases the angle at which the
quadriceps tendon pulls on the shaft of the tibia.
• The patella also functions to allow for smooth
movement of the knee in flexion and extension, and
also protects the anterior surface of the knee joint.

• Tarsals: The tarsal bones of the foot are organized into 3
rows: proximal, intermediate, and distal. The tarsal
bones are the seven bones of the foot, they are:
1. Proximal Group: Talus & Calcaneus
2. Intermediate group: Navicular
3. Distal group: Medial cuneiform, Intermediate cuneiform,
Lateral cuneiform, Cuboid
1.Proximal Group:
• The proximal tarsal bones are the talus and the
calcaneus. forming the bony framework around the
proximal ankle and heel.

• Talus
• The talus is the most superior of the tarsal bones. It transmits
the weight of the entire body to the foot. It has 3
articulations
• Superiorly - ankle joint: between the talus and the bones of
the leg (the tibia & fibula).
• Inferiorly - subtalar joint: between the talus & calcaneus.
• Anteriorly - talonavicular joint: between the talus and the
navicular.
• The main function of the talus is to transmit forces from the
tibia to the heel bone (known as the calcaneus).

• Calcaneus
• The calcaneus is the largest tarsal bone and lies underneath the
talus where it constitutes the heel. It has 2 articulations:
• Superiorly - subtalar (talocalcaneal) joint - between the
calcaneus and the talus.
• Anteriorly - calcaneocuboid joint - between the calcaneus and
the cuboid.
• It protrudes posteriorly and takes the weight of the body as the
heel hits the ground when walking. The posterior aspect of the
calcaneus is marked by calcaneal tuberosity, to which the
Achilles tendon attaches.

• Intermediate group:
• The intermediate row of tarsal bones contains one bone,
the navicular (given its name because it is shaped like a boat). Positioned
medially, it articulates with the talus posteriorly, all 3 cuneiform bones
anteriorly, and the cuboid bone laterally.
• Distal Group:
• In the distal row, there are 4 tarsal bones – the cuboid and the 3
cuneiforms. These bones articulate with the metatarsals of the foot
• The cuboid is furthest lateral, lying anterior to the calcaneus and behind the
fourth and fifth metatarsals. As its name suggests, it is cuboidal in shape.
• The 3 cuneiforms (lateral, intermediate & medial) are wedge shaped
bones. They articulate with the navicular posteriorly, and the metatarsals
anteriorly. The shape of the bones helps form a transverse arch across the
foot. They are also the attachment point for several muscles.

Tarsal bones
Functions:
These bones provide
mechanical support to the
soft foot tissues, helping the
feet withstand the body’s
weight. They form a
longitudinal arch, combining
with other foot bones to act
as a strong weight-bearing
platform while standing or in
motion.

• Metatarsal: The metatarsals are the 5 bones that
make up the middle area of the foot.
• The metatarsal bones are the long bones in your
foot that connect ankle to your toes.
• They also help you balance when you stand and
walk
• The metatarsal bones are convex on their dorsal
surfaces but concave on their plantar surfaces
• the metatarsals are consist of a proximal base, a
shaft and a distal head.
• Joints
• Tarsometatarsal joints, Metatarsophalangeal
joints & Intermetatarsal joints

• Function of the Metatarsal bones:
• Along with the tarsals, the metatarsals help
form the arches of the foot, which are
essential in both weight bearing and walking.
• Along with the calcaneus, the metatarsals are
involved in supporting the weight of the
body.

• Phalanges:
• The phalanges are the bones of the toes.
• There are 14 bones in each.
• The phalanges (single: phalanx) of the feet are the tubular bones of the toes.
• 2nd to 5th toes each contain a proximal, middle and distal phalanx
• Great toe (hallux) only contains a proximal and distal phalanx
• They are similar in structure to the metatarsals, each phalanx consists of a
base, shaft, and head.
• Joints:
• MetaTarsoPhalangeal
• InterPhalangeal (big toe only has one joint)
Proximal InterPhalangeal
Distal InterPhalangeal

• Function of the phalanges in the foot:
• It support body weight
• Maintain the balance and posture
• Serve as a lever that allow to move the body
forward when we walk or run.

Axial
Skull 08
Face 14
Vertebras 26
Ribs 24
Sternum 01
Hyoid 01
Ear bones 06
Total 80
Shoulder girdle
Scapula 02
clavicle 02
Total 04
Pelvic girdle
Hip bone 02
Appendicular (120)
Upper limb
Humerus 02
Radius & ulna 04
Carpals 16
Meta carpals 10
Phalanges 28
Total 60
Lower limb
Femur 02
Tibia & Fibula 04
Patella 02
Tarsals 14
Metatarsals 10
Phalanges 28
Total 60
Total body bones
Axial 80
Shoulder girdle 04
Pelvic girdle 02
Appendicular 120
Total 206

• Joint:
• A joint or articulation is the connection between bones
in the body which link the skeletal system.
• Most joints are mobile, allowing the bones to move
• Types: 3 types
1.Fibrous joint - immovable joint (synarthrosis),
2.Cartilaginous joint - slightly moveable joint
(amphiarthrosis)
3.Synovial joint - freely movable (diarthrosis )

1. Fibrous joint:
• Immovable joints, also known as synarthrosis
• Theses are fixed & because they do not move.
• Fibrous joints have no joint cavity and are
connected via fibrous connective tissue.
• The skull bones are connected by fibrous joints
called sutures. Example: sutures of the skull
2. Cartilaginous joint:
• Slightly moveable joint, also known as
amphiarthrosis
• Cartilaginous joints are a type of joint where the
bones are entirely joined by cartilage, either
hyaline cartilage or fibrocartilage.
• These joints generally allow for slight movements
• Example: intervertebral joints

3. Synovial joint:
• Freely movable joints, also known as diarthrosis & Bones separated by synovial
cavity
• A synovial joint is characterized by the presence of a fluid-filled joint
cavity contained within a fibrous capsule.
• It is the most common type of joint found in the human body
The 3 main features: (i) articular capsule, (ii) articular cartilage, (iii) synovial
fluid.
i) Articular capsule: It surrounds the joint and is continuous with the Periosteum
• It consists of 2 layers:
 Fibrous layer (outer) - It holds together the connecting bones
 Synovial layer (inner) - It absorbs and secretes synovial fluid, and is
responsible for the nutrient exchange between blood and joint. Also known as
the synovium.

ii) Articular Cartilage:
• The articulating surfaces of a synovial
joint are covered by a thin layer of
hyaline cartilage.
• The articular cartilage has two main
roles:
• (1)minimizing friction upon joint
movement,
• (2) absorbing shock.
iii) Synovial Fluid:
• The synovial fluid is located within the
joint cavity of a synovial joint. It has
three primary functions: Lubrication,
Nutrient distribution & Shock absorption.

Types of synovial joints:
a) Pivot joint
b)Hinge joints
c) Saddle joint
d)Plane joints
e) Condyloid joint
f) The ball & socket
joint

• A) Pivot joint:
• Pivot joint, also called rotary joint,
or trochoid joint, that allows only rotary
movement around a single axis.
• The moving bone rotates within a ring
that is formed from a second bone and
adjoining ligament.
• Ex: joint between the atlas and the axis
(first and second cervical vertebrae),
directly under the skull, which allows for
turning of the head from side to side.
Pivot joints also provide for the twisting
movement of the bones of the forearm
(radius and ulna) against the upper arm,

B) Hinge joints:
• It serves to allow motion primarily in
one plane.
• The hinge joint is made up of two or
more bones with articular surfaces that
are covered by hyaline cartilage and
lubricated by synovial fluid.
• Stabilization of each hinge joint is by
muscles, ligaments, & other connective
tissues, such as the joint capsule.
• The hinge joints of the body include the
elbow, knee, interphalangeal (IP) joints
of the hand and foot and the tibiotalar
(ankle) joint of the ankle.

C) Saddle joint:
• The saddle joint gets its name because
the bone forming one part of the joint
is concave (turned inward) at one end
and looks like a saddle.
• The other bone’s end is convex (turned
outward), and looks like a rider in a
saddle.
• Saddle joints are also known as sellar
joints.
• These highly flexible joints are found
in various places in the body, including
the thumb and inner ear.

D) Plane joints:
• Plane joint, also called gliding
joint or arthrodial joint,
• The surfaces of the bones are flat
or nearly flat, enabling the bones
to slide over each other. Because
the articular surfaces of the bones
are free and move in a sliding
motion
• Examples - intercarpal &
intertarsal joint

E) Condyloid joint:
• Condyloid joints, also known as
ellipsoid joints, are composed of
an egg-shaped bone known as a
condyle that fits into a similarly
shaped cavity.
• Although it sounds similar to a ball
and socket joint, Condyloid joints
only allow for forward-backward
and side to side movement and do
not allow rotation.
• An example of Condyloid joints is
the wrist.

F) The ball-and-socket joint:
• Ball and socket joints are composed of
one bone with a rounded head that fits
into the cup of another bone.
• Since the rounded head can move freely
within the cup, or socket, this allows for
movement in all directions.
• Common ball and socket joints include
the hips and shoulders.

• Major joints and structure:
• Shoulder joint
• The shoulder joint (glenohumeral joint) is a ball and socket joint
between the scapula and the humerus. It is the major joint connecting the
upper limb to the trunk.
• It is one of the most mobile joints in the human body.
• Articulating Surfaces
• The shoulder joint is formed by the articulation of the head of the
humerus with the glenoid cavity (or fossa) of the scapula.
• The articulating surfaces are covered with hyaline cartilage. The head of
the humerus is much larger than the glenoid fossa, giving the joint a wide
range of movement at the cost of inherent instability. To reduce the
disproportion in surfaces, the glenoid fossa is deepened by a fibro cartilage
rim, called the glenoid labrum.

• Joint Capsule and Bursae:
• The joint capsule is a fibrous sheath which encloses the
structures of the joint. It extends from the anatomical neck of
the humerus to the border or ‘rim’ of the glenoid fossa. The
joint capsule is lax, permitting greater mobility (particularly
abduction).
• The synovial membrane lines the inner surface of the joint
capsule, and produces synovial fluid to reduce friction between
the articular surfaces.
• To reduce friction in the shoulder joint, several synovial
bursae are present. A bursa is a synovial fluid filled sac, which
acts as a cushion between tendons and other joint structures.

• The bursae that are important clinically are:
• Subacromial bursa: located deep to the deltoid and acromion,
and superficial to the supraspinatus tendon and joint capsule. It
reduces friction beneath the deltoid, promoting free motion of
the rotator cuff tendons.
• Subscapular bursa: located between the subscapularis tendon
and the scapula. It reduces wear and tear on the tendon during
movement at the shoulder joint.
• Subcoracoid bursa: It is located anterior to the
subscapularis muscle and inferior to the coracoid process.
Its function is to reduce friction & facilitating internal and
external rotation of the shoulder

• Ligaments: In the shoulder joint, the ligaments play a key role in stabilizing the
bony structures.
• Glenohumeral ligaments (superior, middle and inferior): the joint capsule is
formed by this group of ligaments connecting the humerus to the glenoid fossa. They
are the main source of stability for the shoulder, holding it in place and preventing it
from dislocating anteriorly. They act to stabilize the anterior aspect of the joint.
• Coracohumeral ligament: attaches the base of the coracoid process to the greater
tubercle of the humerus. It supports the superior part of the joint capsule.
• Transverse humeral ligament: spans the distance between the two tubercles of the
humerus. It holds the tendon of the long head of the biceps in the intertubercular
groove.
• Coraco–clavicular ligament: composed of the trapezoid and conoid ligaments and
runs from the clavicle to the coracoid process of the scapula. They work is to
maintain the alignment of the clavicle in relation to the scapula.
• The other major ligament is the coracoacromial ligament. Running between the
acromion and coracoid process of the scapula it forms the coraco-acromial arch.

• Muscles Acting on Shoulder
Joint:
• Above - Supraspinatus
• Below - Long head of Triceps
• Front - Subscapularis
• Behind - Infraspinatus and
Teres Minor
• Deltoid is placed most
externally and covers the
articulation from its outer side,
as well as in front and behind.

• Movements: As a ball and socket synovial joint - wide
range of movement permitted: Extension
• Flexion
• Abduction
• Adduction
• Blood Supply: Anterior circumflex humeral vessels,
Posterior circumflex humeral vessels, Suprascapular
vessels
• Nerve supply: Axillary nerve, Musculocutaneous
nerve, Suprascapular Nerve & Lateral pectoral nerve
•Internal rotation.
•External rotation
•Circumduction

• Hip joint:
• The hip joint is the largest
weight-bearing joint in the
human body.
• It is also referred to as a ball &
socket joint and is surrounded
by muscles, ligaments and
tendons.
• The thighbone or femur and
the pelvis join to form the hip
joint.

• The hip joint is made up of the following:
• Bones and joints
• Ligaments of the joint capsule
• Muscles and tendons
• Nerves and blood vessels that supply the bones and muscles of the hip
• Bones and Joints of the Hip:
• The hip joint is the junction where the hip joins the leg to the trunk of the
body. It is comprised of two bones: the thighbone or femur, and the
pelvis (ilium, ischium & pubis)
• The ball of the hip joint is made by the femoral head while the socket is
formed by the acetabulum. The acetabulum is a deep, circular socket
formed on the outer edge of the pelvis by the union of three bones:
ilium, ischium and pubis.

• The stability of the hip is provided by the joint capsule or
acetabulum and the muscles and ligaments that surround and
support the hip joint.
• The head of the femur rotates and glides within the acetabulum. A
fibrocartilaginous lining called the labrum is attached to the
acetabulum and further increases the depth of the socket.
• Next to the femoral neck, there are two protrusions known as
greater and lesser trochanters which serve as sites of muscle
attachment.
• Articular cartilage is the thin, tough, flexible and slippery surface
lubricated by synovial fluid that covers the weight-bearing bones of
the body. It enables smooth movements of the bones and reduces
friction

• Ligaments of the Hip Joint:
• Ligaments are fibrous structures that connect bones to other
bones. The hip joint is encircled with ligaments to provide
stability to the hip by forming a dense and fibrous structure
around the joint capsule.
• The ligaments adjoining the hip joint include:
• Iliofemoral ligament: This is a Y-shaped ligament that
connects the pelvis to the femoral head at the front of the joint.
It helps in limiting over-extension of the hip.
• Pubofemoral ligament: This is a triangular shaped ligament
that extends between the upper portion of the pubis and the
iliofemoral ligament. It attaches the pubis to the femoral head.

• Ischiofemoral ligament: This is a group of strong fibers
that arise from the ischium behind the acetabulum and
merge with the fibers of the joint capsule.
• Ligamentum teres: This is a small ligament that extends
from the tip of the femoral head to the acetabulum.
Although it has no role in hip movement, it does have a
small artery within that supplies blood to a part of the
femoral head.
• Acetabular labrum: The labrum is a fibrous cartilage
ring which lines the acetabular socket. It deepens the
cavity increasing the stability and strength of the hip joint.

• Muscles and Tendons of the Hip Joint: A long tendon called the iliotibial
band runs along the femur from the hip to the knee
• Gluteal: These are the muscles that form the buttocks. There are three
muscles (gluteus minimus, gluteus maximus, and gluteus medius) that
attach to the back of the pelvis and insert into the greater trochanter of the
femur.
• Adductors: These muscles are in the thighs which help in adduction, the
action of pulling the leg back towards the midline.
• Iliopsoas: This muscle is in front of the hip joint and provides flexion.
• Rectus femoris: This is the largest band of muscles located in front of the
thigh. They are also called hip flexors.
• Hamstring muscles: These begin at the bottom of the pelvis and run down
the back of the thigh. Because they cross the back of the hip joint, they help
in extension of the hip by pulling it backwards.

• Hip Movements:
• All the anatomical parts of the hip work together to enable
various movements.
• Hip movements include
• Flexion
• Extension
• Abduction
• Adduction
• Circumduction
• Hip rotation.

• Nerves and Arteries of the Hip Joint
• Nerves of the hip transfer signals from the brain to the muscles
to aid in hip movement. They also carry the sensory signals
such as touch, pain, and temperature back to the brain. The
main nerves in the hip region include the femoral nerve in the
front of the femur and the sciatic nerve at the back.
• The hip is also supplied by a smaller nerve known as the
obturator nerve. In addition to these nerves, there are blood
vessels that supply blood to the lower limbs. The femoral
artery, one of the largest arteries in the body, arises deep in the
pelvis and can be felt in front of the upper thigh.

• Knee joint: The knee joint is a hinge type synovial joint,
which mainly allows for flexion and extension (and a small
degree of medial and lateral rotation). It is formed by
articulations between the patella, femur and tibia.

• Articulating Surfaces
• The knee joint consists of two articulations: tibiofemoral &
patellofemoral. The joint surfaces are lined
with hyaline cartilage and are enclosed within a single joint
cavity.
• Tibiofemoral: medial & lateral condyles of the femur articulate
with the tibial condyles. It is the weight-bearing component of
the knee joint.
• Patellofemoral: anterior aspect of the distal femur articulates
with the patella. It allows the tendon of the quadriceps femoris
(knee extensor) to be inserted directly over the knee –
increasing the efficiency of the muscle.

• As the patella is both formed and resides within the quadriceps
femoris tendon, it provides a central point to increase power of
the knee extensor and serves as a stabilizing structure that
reduces frictional forces placed on femoral condyles.

• Menisci: A meniscus is a piece of cartilage found where two bones meet (joint
space). Menisci (plural of meniscus) protect and cushion the joint surface
and bone ends. In the knee, the crescent-shaped menisci are positioned
between the ends of the upper (femur) and lower (tibia) leg bones.
• The medial and lateral menisci are fibro cartilage structures in the knee that
serve two functions:
1. To deepen the articular surface of the tibia, thus increasing stability of the
joint.
2. To act as shock absorbers by increasing surface area to further dissipate
forces.
• They are C shaped and attached at both ends to the intercondylar area of the
tibia.
• In addition to the intercondylar attachment, the medial meniscus is fixed to
the tibial collateral ligament and the joint capsule. The lateral meniscus is
smaller and does not have any extra attachments, rendering it fairly mobile

• Bursae: A bursa is synovial fluid filled sac, found between moving
structures in a joint – with the aim of reducing wear and tear on
those structures. There are four bursae found in the knee joint:
• Suprapatellar bursa: an extension of the synovial cavity of the
knee, located between the quadriceps femoris and the femur.
• Prepatellar bursa: found between the apex of the patella and the
skin.
• Infrapatellar bursa: split into deep and superficial. The deep bursa
lies between the tibia and the patella ligament. The superficial lies
between the patella ligament and the skin.
• Semimembranosus bursa: located Posteriorly in the knee joint,
between the semimembranosus muscle & the medial head of the
gastrocnemius

• Ligaments: The major ligaments in the knee joint are:
• Patellar ligament: a continuation of the quadriceps femoris tendon
distal to the patella. It attaches to the tibial tuberosity.
• Collateral ligaments: two strap-like ligaments. They act to stabilize the
hinge motion of the knee, preventing excessive medial or lateral
movement
1. Tibial (medial) collateral ligament: wide and flat ligament, found on
the medial side of the joint. Proximally, it attaches to the medial
epicondyle of the femur, distally it attaches to the medial condyle of the
tibia.
2. Fibular (lateral) collateral ligament: thinner and rounder than the
tibial collateral, this attaches proximally to the lateral epicondyle of the
femur, distally it attaches to a depression on the lateral surface of the
fibular head.

• Cruciates Ligaments: these two ligaments connect the femur
and the tibia. In doing so, they cross each other, hence the term
‘cruciate’ (Latin for like a cross)
1. Anterior cruciate ligament: attaches at the anterior
intercondylar region of the tibia where it blends with the
medial meniscus. It ascends posteriorly to attach to the femur
in the intercondylar fossa. It prevents anterior dislocation of
the tibia onto the femur.
2. Posterior cruciate ligament: attaches at the posterior
intercondylar region of the tibia and ascends anteriorly to
attach to the anteromedial femoral condyle. It prevents
posterior dislocation of the tibia onto the femur.

• Movements: There are four main movements that the knee joint
permits:
• Extension
• Flexion
• Lateral rotation
• Medial rotation
• Lateral and medial rotation can only occur when the knee is flexed
(if the knee is not flexed, the medial/lateral rotation occurs at the
hip joint).
• Neurovascular Supply: The blood supply: through the genicular
anastomoses around the knee, which are supplied by the genicular
branches of the femoral & popliteal arteries.
• The nerve supply: femoral, tibial and common fibular nerves.

1. Unit - 7- Skeleton anatomy by Thiru murugan

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1. Unit - 7- Skeleton anatomy by Thiru murugan