In human anatomy, the head is at the top of the human body. It is maintained by the skull, which itself encloses the brain; the human head consists of a fleshy outer portion. The brain is enclosed within the skull; the head rests on the neck, the seven cervical vertebrae support it. The human head weighs between 5 and 11 pounds The face is the anterior part of the head, containing the eyes and mouth. On either side of the mouth, the cheeks provide a fleshy border to the oral cavity; the ears sit to either side of the head. The head receives blood supply through the external carotid arteries; these supply the area outside of the inside of the skull. The area inside the skull receives blood supply from the vertebral arteries, which travel up through the cervical vertebrae; the twelve pairs of cranial nerves provide the majority of nervous control to the head. The sensation to the face is provided by the branches of the trigeminal nerve, the fifth cranial nerve. Sensation to other portions of the head is provided by the cervical nerves.
Modern texts are in agreement about which areas of the skin are served by which nerves, but there are minor variations in some of the details. The borders designated by diagrams in the 1918 edition of Gray's Anatomy are similar but not identical to those accepted today; the cutaneous innervation of the head is as follows: Ophthalmic nerve Maxillary nerve Mandibular nerve Cervical plexus Dorsal rami of cervical nerves and others are in picture which show following in upper column The head contains sensory organs: two eyes, two ears, a nose and tongue inside of the mouth. It houses the brain. Together, these organs function as a processing center for the body by relaying sensory information to the brain. Humans can process information faster by having this central nerve cluster. For humans, the front of the head is the main distinguishing feature between different people due to its discernible features, such as eye and hair colors, shapes of the sensory organs, the wrinkles. Humans differentiate between faces because of the brain's predisposition toward facial recognition.
When observing a unfamiliar species, all faces seem nearly identical. Human infants are biologically programmed to recognize subtle differences in anthropomorphic facial features. People who have greater than average intelligence are sometimes depicted in cartoons as having bigger heads as a way of notionally indicating that they have a "larger brain". Additionally, in science fiction, an extraterrestrial having a big head is symbolic of high intelligence. Despite this depiction, advances in neurobiology have shown that the functional diversity of the brain means that a difference in overall brain size is only to moderately correlated to differences in overall intelligence between two humans; the head is a source for many metaphors and metonymies in human language, including referring to things near the human head, things physically similar to the way a head is arranged spatially to a body and things that represent some characteristics associated with the head, such as intelligence. Ancient Greeks had a method for evaluating sexual attractiveness based on the Golden ratio, part of which included measurements of the head.
Headpieces can signify status, religious/spiritual beliefs, social grouping, team affiliation, occupation, or fashion choices. In many cultures, covering the head is seen as a sign of respect; some or all of the head must be covered and veiled when entering holy places or places of prayer. For many centuries, women in Europe, the Middle East, South Asia have covered their hair as a sign of modesty; this trend has changed drastically in Europe in the 20th century, although is still observed in other parts of the world. In addition, a number of religions require men to wear specific head clothing—such as the Islamic Taqiyah, Jewish yarmulke, or the Sikh turban; the same goes for Christian nun's habit. A hat is a head covering. Hats may be worn as part of a uniform or used as a protective device, such as a hard hat, a covering for warmth, or a fashion accessory. Hats can be indicative of social status in some areas of the world. While numerous charts detailing head sizes in infants and children exist, most do not measure average head circumference past the age of 21.
Reference charts for adult head circumference generally feature homogeneous samples and fail to take height and weight into account. One study in the United States estimated the average human head circumference to be 55 centimetres in females and 57 centimetres in males. A British study by Newcastle University showed an average size of 55.2 cm for females and 57.2 cm for males with average size varying proportionally with height Macrocephaly can be an indicator of increased risk for some types of cancer in individuals who carry the genetic mutation that causes Cowden syndrome. For adults, this refers to head sizes greater than 58 centimeters in men or greater than 57 centimeters in women. Human body Head and neck anatomy 8. Human head Campbell, Bernard Grant. Human Evolution: An Introduction to Man's Adaptations, 4th edition
In the vertebrate spinal column, each vertebra is an irregular bone with a complex structure composed of bone and some hyaline cartilage, the proportions of which vary according to the segment of the backbone and the species of vertebrate. The basic configuration of a vertebra varies; the upper and lower surfaces of the vertebra body give attachment to the intervertebral discs. The posterior part of a vertebra forms a vertebral arch, in eleven parts, consisting of two pedicles, two laminae, seven processes; the laminae give attachment to the ligamenta flava. There are vertebral notches formed from the shape of the pedicles, which form the intervertebral foramina when the vertebrae articulate; these foramina are the exit conducts for the spinal nerves. The body of the vertebra and the vertebral arch form the vertebral foramen, the larger, central opening that accommodates the spinal canal, which encloses and protects the spinal cord. Vertebrae articulate with each other to give strength and flexibility to the spinal column, the shape at their back and front aspects determines the range of movement.
Structurally, vertebrae are alike across the vertebrate species, with the greatest difference seen between an aquatic animal and other vertebrate animals. As such, vertebrates take their name from the vertebrae; each vertebra is an irregular bone. The size of the vertebrae varies according to placement in the vertebral column, spinal loading and pathology. Along the length of the spine the vertebrae change to accommodate different needs related to stress and mobility; every vertebra has a body, which consists of a large anterior middle portion called the centrum and a posterior vertebral arch called a neural arch. The body is composed of cancellous bone, the spongy type of osseous tissue, whose micro-anatomy has been studied within the pedicle bones; this cancellous bone is in turn, covered by a thin coating of cortical bone, the hard and dense type of osseous tissue. The vertebral arch and processes have thicker coverings of cortical bone; the upper and lower surfaces of the body of the vertebra are flattened and rough in order to give attachment to the intervertebral discs.
These surfaces are the vertebral endplates which are in direct contact with the intervertebral discs and form the joint. The endplates are formed from a thickened layer of the cancellous bone of the vertebral body, the top layer being more dense; the endplates function to contain the adjacent discs, to evenly spread the applied loads, to provide anchorage for the collagen fibers of the disc. They act as a semi-permeable interface for the exchange of water and solutes; the vertebral arch is formed by pedicles and laminae. Two pedicles extend from the sides of the vertebral body to join the body to the arch; the pedicles are short thick processes that extend, one from each side, from the junctions of the posteriolateral surfaces of the centrum, on its upper surface. From each pedicle a broad plate, a lamina, projects backwards and medialwards to join and complete the vertebral arch and form the posterior border of the vertebral foramen, which completes the triangle of the vertebral foramen; the upper surfaces of the laminae are rough to give attachment to the ligamenta flava.
These ligaments connect the laminae of adjacent vertebra along the length of the spine from the level of the second cervical vertebra. Above and below the pedicles are shallow depressions called vertebral notches; when the vertebrae articulate the notches align with those on adjacent vertebrae and these form the openings of the intervertebral foramina. The foramina allow the entry and exit of the spinal nerves from each vertebra, together with associated blood vessels; the articulating vertebrae provide a strong pillar of support for the body. There are seven processes projecting from the vertebra. A major part of a vertebra is a backward extending spinous process; this process points caudally from the junction of the laminae. The spinous process serves to attach ligaments; the two transverse processes, one on each side of the vertebral body, project from either side at the point where the lamina joins the pedicle, between the superior and inferior articular processes. They serve for the attachment of muscles and ligaments, in particular the intertransverse ligaments.
There is a facet on each of the transverse processes of thoracic vertebrae which articulates with the tubercle of the rib. A facet on each side of the thoracic vertebral body articulates with the head of the rib. There are superior and inferior articular facet joints on each side of the vertebra, which serve to restrict the range of movement possible; these facets are joined by a thin portion of the vertebral arch called the pars interarticularis. The transverse process of a lumbar vertebra is sometimes called the costal or costiform process because it corresponds to a rudimentary rib which, as opposed to the thorax, is not developed in the lumbar region. Vertebrae take their names from the regions of the vertebral column. There are thirty-three vertebrae in the human vertebral column—seven cervical vertebrae, twelve thoracic vertebrae, five lumbar vertebrae, five fused sacral vertebrae forming the sacrum and three to five coccygeal vertebrae, forming the coccyx; the regional vertebrae increase in size as they become smaller in the coccyx.
There are seven cervical vertebrae
A Smith's fracture sometimes known as a reverse Colles' fracture or Goyrand-Smith's, is a fracture of the distal radius. It is caused by a direct blow to the dorsal forearm or falling onto flexed wrists, as opposed to a Colles' fracture which occurs as a result of falling onto wrists in extension. Smith's fractures are less common than Colles' fractures; the distal fracture fragment is displaced volarly, as opposed to a Colles' fracture which the fragment is displaced dorsally. Depending on the severity of the impact, there may be one or many fragments and it may or may not involve the articular surface of the wrist joint; this fracture is named after the orthopedic surgeon, Robert William Smith in his book A Treatise on Fractures in the Vicinity of Joints, on certain forms of Accidents and Congenital Dislocations published in 1847. Treatment of this fracture depends on the severity of the fracture. An undisplaced fracture may be treated with a cast alone. A fracture with mild angulation and displacement may require closed reduction.
Significant angulation and deformity may require internal fixation. An open fracture will always require surgical intervention. Radiograph of Smith's fracture
Chalkstick fractures are fractures of long bones, in which the fracture is transverse to the long axis of the bone, like a broken stick of chalk. A healthy long bone breaks like a hard woody stick as the collagen in the matrix adds remarkable flexibility to the mineral and the energy can run up and down the growth rings of bone; the bones of children will follow a greenstick fracture pattern. Chalkstick fractures are common in Paget's disease of bone, osteopetrosis
A greenstick fracture is a fracture in a young, soft bone in which the bone bends and breaks. Greenstick fractures occur most during infancy and childhood when bones are soft; the name is by analogy with green wood which breaks on the outside when bent. It was discovered by British-American orthopedist, John Insall, Polish-American orthopedist, Michael Slupecki; some clinical features of a greenstick fracture are similar to those of a standard long bone fracture - greenstick fractures cause pain at the injured area. As these fractures are a pediatric problem, an older child will be protective of the fractured part and babies may cry inconsolably; as per a standard fracture, the area may be swollen and either bruised. Greenstick fractures are stable fractures as a part of the bone remains intact and unbroken so this type of fracture causes a bend to the injured part, rather than a distinct deformity, problematic. Symptoms can start from overuse in that specific bone; this can be a gradual chronic pain or pain from a specific injury.
The greenstick fracture pattern occurs as a result of bending forces. Activities with a high risk of falling are risk factors. Non-accidental injury more causes spiral fractures but a blow on the forearm or shin could cause a green stick fracture; the fracture occurs in children and teens because their bones are flexible, unlike adults whose more brittle bones break. Pediatric fractures can be classified as complete and incomplete: Incomplete: there are three basic forms of incomplete fractures: The first is the greenstick fracture, a transverse fracture of the cortex which extends into the midportion of the bone and becomes oriented along the longitudinal axis of the bone without disrupting the opposite cortex; the second form is a buckling fracture, caused by impaction. They are the result of a force acting on the longitudinal axis of the bone: they are a consequence of a fall on an outstretched arm, so they involve the distal radial metaphysis; the word torus is derived from the Latin word'torus,' meaning swelling or protuberance.
The third is a bow fracture. Complete fracturesThere are physeal fractures; the Salter-Harris classification is the most used to describe these fractures. Removable splints result in better outcomes than casting in children with torus fractures of the distal radius. If a person is doing better after 4 weeks, repeat X rays are not needed. Evidence for greenstick fractures found in the fossil record is studied by paleopathologists, specialists in ancient disease and injury. Greenstick fractures have been reported in fossils of the large carnivorous dinosaur Allosaurus fragilis. Greenstick fractures are found in the fossil remains of Lucy, the most famous specimen of Australopithecus afarensis, discovered in Ethiopia in 1974. Analysis of bone fracture patterns, which include a large number of greenstick fractures in the forearms, lower limbs, pelvis and skull, suggest that Lucy died from a vertical fall and impact with the ground. Radiology Greenstick vs Torus Fractures
Proximal humerus fracture
A proximal humerus fracture is a break of the upper part of the bone of the arm. Symptoms include pain, a decreased ability to move the shoulder. Complications may include axillary artery injury; the cause is a fall onto the arm or direct trauma to the arm. Risk factors include diabetes. Diagnosis is based on X-rays or CT scan, it is a type of humerus fracture. A number of classification systems exist. Treatment is with an arm sling for a brief period of time followed by specific exercises; this appears appropriate in many cases when the fragments are separated. Less surgery is recommended. Proximal humerus fractures are common. Older people are most affected. In this age group they are the third most common fractures after Colles fractures. Women are more affected than men. Typical signs and symptoms include pain, swelling and limited range of motion at the shoulder. Deformity may be present in severe fractures, musculature may cause absence of deformity on inspection. Numbness over the outside part of the upper arm and deltoid muscle weakness may indicate axillary nerve injury.
Symptoms from poor blood circulation in the arm is uncommon due to collateral circulation in the arm. People with increased risk of falls are more to have a proximal humerus fracture, as this is the most common mechanism of injury. Osteoporosis increases the risk of proximal humerus fractures. Young adults without risk factors require significant trauma, such as in the setting of a motor vehicle collision. Older adults more experience proximal humerus fractures after a fall from standing height; the shoulder joint consists of the head of the humerus. It as an mobile joint, stabilized by surrounding soft tissues such as the joint capsule and ligaments; the greater and lesser tuberosities are bony landmarks of the proximal humerus and serve as attachment sites for musculature. The anterior and posterior humeral circumflex arteries branch off of the axillary artery to provide the majority of the blood supply to the proximal humerus; the axillary nerve courses inferior to the shoulder joint and innervates the deltoid and teres minor muscles.
It provides sensation at the skin overlying the shoulder. This nerve is the most injured nerve in proximal humerus fractures due to its location close to the proximal humerus. Muscles that attach to the proximal humerus and can cause a deforming force on fracture fragments include the pectoralis major, the deltoid, the rotator cuff muscles; the standard x-ray views of the shoulder include a true anterior-posterior view, a lateral view, an axillary view. A Velpeau view can be done as an alternative to the axillary view if an examinee is unable to position the shoulder for an appropriate image; this can be obtained by having the examinee lean backward 45 degrees while an xray beam is aiming towards the floor. A CT scan of the injured shoulder can be done to help further characterize the fracture and determine articular involvement. CT scan is an option if an axillary view is unattainable. MRI is not indicated in the setting of proximal humerus fracture, although it may be useful in assessing injury to soft tissue structures such as the rotator cuff muscles.
The Neer classification of proximal humerus fractures is the most used classification system. It classifies fractures depending on the number of segments, whether or not there is displacement present; this classification has a low amount of agreement between physicians using the classification system, although formal training sessions may improve agreement. The AO/OTA classification system is another used system that groups fractures depending on whether the fracture is unifocal or bifocal, whether or not the fracture goes through the articular surface. There are both surgical options for treatment of proximal humerus fractures; the recommended treatment is decided based on fracture stability as determined with imaging and clinical exam. Most proximal humerus fractures can be treated without surgery. Typical non-operative treatment consists of shoulder immobilization with a sling. Close follow-up and weekly x-rays are recommended in order to ensure that the fracture is healing and maintaining good alignment.
Passive range of motion exercises for the shoulder can be done. This can be done without the assistance of a physical therapist; when properly indicated, non-surgical treatment options for proximal humerus fractures have good outcomes in terms of fracture healing and restoration of arm function. Surgical options for unstable proximal humerus fractures include: Closed reduction with percutaneous pinning Open reduction with internal fixation Intramedullary rod fixation Shoulder arthroplasty Reverse shoulder arthroplasty Proximal humerus fractures account for 4-7% of all fractures in adults, it is the most common fracture of the humerus, as well as the most common fracture at the shoulder girdle. They are more common in women than men, occur more in older adults; the average age of people who sustain a proximal humerus fracture is 63–66 years. A proximal humerus fracture in a young child may be a sign of child abuse. In older children and adolescents proximal humerus fractures occur in the setting of sports or trauma.
Proximal humerus fractures in children can be treated non-operatively due to the large amount of bone growth that occurs at the proximal humerus. In older children where there is less time for bone remodeling, surgery may be indicated more frequently
Flexion teardrop fracture
A flexion teardrop fracture is a fracture of the anteroinferior aspect of a cervical vertebral body due to flexion of the spine along with vertical axial compression. The fracture continues sagittally through the vertebral body, is associated with deformity of the body and subluxation or dislocation of the facet joints at the injured level. A flexion teardrop fracture is associated with a spinal cord injury a result of displacement of the posterior portion of the vertebral body into the spinal canal; the flexion teardrop fracture should not be confused with a similar-looking vertebral fracture called "extension teardrop fracture". Both occur in the cervical spine, but as their names suggest, they result from different mechanisms. Both are associated with a small fragment being broken apart from the anteroinferior corner of the affected vertebra. Flexion teardrop fractures involve instability in all elements of the spine at the injured level occur at the C4-C7 vertebra, have a high association with spinal cord injury.
In comparison, the extension-type fracture occurs more at C2 or C3, causes less if any disruption to the middle and posterior elements, does not result in spinal cord injury