Bones of the skeleton
Functions of the skeleton are to/form : -
Framework
Cavities
Fossae
Protect
Joints
Muscular attachments
Formation of blood
Classification
skeleton can be broadly classified as : -
Axial skeleton consists of
Skull
Vertebral column
Sternum
Ribs
Appendicular skeleton consists of :
Bones of the upper limb, the two clavicles and the two scapulae
The bones of the lower limbs and the two innominate bones of the pelvis
Axial skeleton
Skull - mandible = Cranium
Cranium = Facial bones + bones of the cranial cavity
Develop separately
Mandible
Temporal bones
Sides of head - join with parietal, occipital, sphenoid and zygomatic bones -
Four parts - squamous part fan shaped
Mastoid process sinuses - communicated with middle ear - squamous epithelium
Petrous portion base organ of hearing, spiral organ of Corti
Zygomatic process articulates with the zygomatic bone to form the zygomatic arch.
Temporomandibular joints - behind is the auditory meatus which passes inwards towards the petrous portion of the bone.
Occipital bone
Back of head - part of base - concave - occipital lobes of cerebrum, cerebellum- two articular condyles hinge joint with C1 - foramen magnum spinal cord passes
Sphenoid bone
Middle portion of the base of the skull
Articulates with the temporal, parietal and frontal bones.
Saddle shaped depression, hypophyseal fossa (sella turcica) pituitary
Body sinuses - lined by ciliated mucous membrane nasal cavity
Ethmoid bone
Anterior - base - part of orbital cavity - nasal septum lateral wall - turbinates upper and middle conchae - sinuses lined with ciliated epithelium. Cribriform plate - horizontal plate - olfactory nerves. Fine vertical plate nasal septum.
Facial bones
13 bones in addition to frontal bone
2 zygomatic or cheek bones
1 maxilla ( originated as 2)
2 nasal bones
2 lacrimal bones
1 vomer
2 palatine
2 inferior concha or turbinate bones
1 mandible originate as 2
zygomatic bone or cheek bone
nose, eye socket floor.
Maxilla or upper jaw bone
Originate as two bones
Alveolar ridges
Teeth
Ciliated mucous membrane
Nasal bones
Lacrimal bones
Posterior and lateral to the nasal bones - laeral wall of the nasal cavity - nasolacrimal ducts - medial canthus to nose
Vomer
Hardpalate to perpendicular plate of the ethmoid bone.
Palatine bones
L shaped - horizontal parts unite to form the posterior part of the hard palate and the perpendicular parts project upwards to form part of the lateral walls of the nasal cvities. Upper orbital cavities.
Turbinate bones Inferior conchae
Lateral wall of the nasal cavity
Mandible
Movable
Develops as 2
Body, alveolar ridge, ramus condyloid process articulates with the temporal bone temporomandibular joint. - coronoid process attachements to m. ligs. Angle
Hyoid bone
Horse shoe shaped bone above larynx below mandible
Attached to the styloid process of the temporal bone by ligaments gives attachment to the base of tongue.
Sinuses
Sphenoid ethmoid maxillary and frontal bones
Communicate with the nose
Ciliated mucous membrane
Resonance
Lighten the bones
Frontanelles of the skull
Sutures incomplete
Ant and post
Moulding
caput
Functions
Cranium protects brain
Eye sockets protect eye balls muscle attachment recti orbicularis
Temporal - ear
Sinuses - resonance open into nose
Maxilla teeth
Mandible teeth chew,
Vertebral Column
24 movable bones + sacrum + coccyx
discs
7 cervical
12 thoracic
5 lumbar
1 sacrum (5 fused bone)
1 coccyx ( 4 fused bones)
Atlas - articulates with the skull
Axis - lends the axis for the pivotal joint between atlas and axis - odantoid process
facilitates rotation movements of the skull
Sacrum - articulates with hip and 5th lumbar vertebra, coccyx
Functions Of The Vertebral Column
protects the spinal cord
Lodges and protects the spinal cord - an extension of nerve tissue from the brain - in the spinal canal
permits issue of peripheral nerves through their foramen - neural canal - spinal nerves 31 pairs
in the thoracic region ribs articulate with the vertebrae forming joints which move during respiration. And forms thoracic cage.
Functions Of The Thoracic Cage
Protect the thoracic oragans heart, lungs, large blood vessels
Joint between upper libms and the axial skeleton
Give attachment to muscles of respiration : intercostal muscles move cage upward and outward expansion - inspiration; diaphragm forms a partition betwee the thoracic and abdominal cavities.
Appendicular Skeleton
The appendages are :
- Shoulder girdle (scapula and clavicle) with the upper limbs
- Pelvic girdle (innominate bones) with the lower limbs
Shoulder girdle and upper limb
1 clavicle
1 scapula
1 humerus
1 radius
1 ulna
8 carpals bones
5 metacarpals
14 phalanges
Clavicle or collar bone
Long
Double curve
Articulates with manubrium sterni - sternoclavicular joint
Articulates with acromion process of the scapula - acromioclavicular joint.
Clavicle the only bony link to axial skeleton for the upper limb
Scapula
The shoulder blade is flat - triangular
On the posterior chest
Superficial to the ribs
Separated from them by muscles
Lateral part glenoid cavity + head of humerus shoulder joint.
Posterior surface - spine of scapula
Acromion process formed by lateral extension of the spine of scapula
Acromion process aritculates with clavicle - Acromioclavicular joint
Coracoid process - a projection from the upper border of the bone
It gives attachments to muscles of the shoulder
Supraspinatus fossa is the shallow pit above the spine of scapula
Infraspinatus fossa is the shallow fossa below the spine of scapula called
The fossae give rise to muscles called infraspinatus muscle and supraspinatus muscle respectively.
Humerus
Upper arm bone
Parts
Head seated in the glenoid cavity of scapula - shoulder joint
Greater and lesser tubercles
Between the tubercle there is a deep groove - bicipital groove
Deltoid tuberosity- on the lateral surface of the humerus where the deltoid muscle is attached
Distal end two surfaces to articulate with the ulna and radius - trochlea and capitulum. Lateral and medial epicondyles
Medial supracondylar ridge -
lateral supracondylar ridge.- coronoid fossa.
Radius
Lateral bone of the forearm
Parts :
Head of radius
Neck of radius
Radial tuberosity
Shaft of radius
At the upper end articulates with the ulna - proximal radioulnar.
At the lower end articulates with the carpal bones to form wrist joint.
Styloid process - a sharp process at the lower end.
Ulna
The medial bone of the forearm
At the upper end articulate with humerus to form elbow joint
At the lower end articulates with radius inferior radioulnar joints
Interosseous membrane holds ulna with the radius and forms a sheet
The other parts are Trochlear notch - coronoid process - shaft of ulna - ulnar styloid
Carpal or Wrist Bones
Closely fitted together by ligaments
In two rows
Proximal row wrist joint with radius
Tendons and muscles lying in the forearm cross the wrist and are held close to the bones by strong fibrous bands called retinacula - flexor and extensor retinacula
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Metacarpal Bones
5 in number - form palm - proximal ends articulate with the carpal bones and the distal ends with the phalanges.
Phalanges or finger bones
14 phalanges - two in the thumb - 3 in the others Metacarpo-phalangeal joints- proximal interphalangeal joints - distal interphalangeal joints.
Pelvic girdle and lower limb
Bones of the pelvic girdle
2 innominate bones and 1 sacrum
the bones of the lower extremity are:-
1 femur
1 tibia
1 fibula
1patella
7 tarsal bones
5 metatarsal bones
14 phalanges
Innominate or hip bones & lower limbs
Three fused bones - the ilium, ischium and pubis
The pit formed by all the three - acetabulum hip joint with head of femur.
Ilium is the upper flattened part of the bone
The parts are - iliac crest - anterior superior iliac spine - pubis anterior part of the bone - articulates with the pubis of the other hip bone - cartilagenous joint, the symphysis pubis.
Ischium is the inferior and posterior part.
The pelvis
Pelvis is formed by two innominate bones.
Anteriorly symphysis pubis
Posteriorly articulates with the sacrum at the sacroiliac joints
Divided into two parts by the brim of the pelvis, promontaory of the sacrum , iliopectineal lines of the innominate bones
Greater or false pelvis above the brim and the lesser or true pelvis below.
Differences between male and female pelves
Shape allows for the passage of the baby during childbirth.
Female pelvis is made of lighter bones
Shallow
Rounded
More roomy
Femur or thigh bone
Longest and strongest
Parts :
Head - spherical - articulates at acetabulum - hip joint
Depression in head for ligament of the head of the femur - contains blood vessel -
Neck - most of the neck within the capsule of the hip joint
- posterior surface called linea aspera - gives attachments to muscles
Popliteal surface
Distally two articular condyles - articulate with tibia and fibula to form the knee joint
Tibia or shin bone
Leg bone
Situated medially
Parts :-
Two condyles at the upper end; lateral and medial condyles - form knee joint with femur
Inferior aspect of the lateral condyle articulates with the head of the fibula, forming the superior tibiofibular joint.
Distal end articulates with the talus - ankle joint
And the fibula - inferior tibiofibular joint
The elongated process called Medial malleolus
Fibula
Long slender Lateral bone of the leg.
Head articulates with the lateral condyle of the tibia - superior tibiofibular joint
Lower extremity articulates with the tibia then projects beyond it to form the lateral malleolus.
The medial aspect of the lower end articulates with the tibia to form the inferior tibiofibular joint
Patella or knee cap
Triangular
Sesamoid bone
In front of knee joint
Posterior surface articulates with the patellar surface of the femur in the knee joint
Its anterior surface is in the patellar tendon - quadriceps femoris muscle - tendon
Tarsal or ankle bones
Seven -
1 talus
1 calcaneus
1 navicular
3 cuneiforms
1 cuboid
The talus articulates with the tibia and fibula at the ankle joint and the other bones articulate with each other and with metatarsal bones.
Metatarsal bones
Five - proximal part articulates with the tarsal bones and at their distal ends, with the phalanges.
Phalanges
14
Arches of the foot
Arrangement of the bones of the foot like a bridge supported by muscles and ligaments - four arches - a medial and lateral longitudinal arch and two transverse arches.
Medial longitudinal arch
Highest arch
Formed by - calcaneus, navicular, three cuneiform and first three metatarsal bones - only the calcaneus and the distal end of the metatarsal bones touch the ground.
Lateral longitudinal arch
Less marked - bony components are the calcaneus, cuboid and the two lateral metatarsal bones.
Transverse arches
Run across the foot and can be more easily seen by examining the skeleton than the live model - most marked at the level of the three cuneiform and cuboid bones.
Muscles and ligaments which support the arches of the foot
Movable joints - hence very strong muscles and ligaments are necessary to maintain the strength, resilience and stability of the foot during walking, running and jumping.
Posterior tibialis muscle
Most important muscular support of the medial longitudinal arch
Originates from the middle third of the tibia and fibula posteriorly
Its tendon passes behind the medial malleolus
Inserted into the navicular, cuneiform, cuboid and metatarssal bones.
Forms a sling or suspension apparatus for the arch.
Short muscles of the foot
This group of muscles is mainly concerned with the maintenance of the lateral longitudinal and transverse arches - they make up the fleshy part of the sole of the foot.
Plantar calcaneonavicular ligament or spring ligament
Very strong thick ligament stretching from the calcaneus to the navicular bone.
It supports the medial longitudinal arch.
Plantar ligaments and interosseous membranes
Support lateral and transverse arches.
Functions of the Appendicular Skeleton
" Voluntary movements. Writing running jumping
" Protection of structures like blood vessels nerves,
Cavities fo the Body
1. Cranial
2. Thoracic
3. Abdominal
4. Pelvic
Cranial Cavity
Contains brain, boundaries
Anteriorly _______________ 1 frontal bone
Laterally _______________ 2 temporal bones
Posteriorly _______________ 1 occipital bone
Superiorly _______________ 2 parietal bones
Inferiorly _______________ 1 sphenoid and 1 ehtmoid bone and parts of the . frontal,temporal and occipital bones
