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Showing posts with label AnatomyPhysiology. Show all posts
Showing posts with label AnatomyPhysiology. Show all posts

Wednesday, May 5, 2021

Gluteal Compartment Anatomy

Gluteal Compartment Anatomy


Gluteal Compartment Anatomy
The gluteal region or buttock forms part of the root of the limb. It overlies the dorsum of the ilium, ischium and sacrum and is continuous proximally with the lower trunk and distally with the posterior compartment of the thigh. Three substantial muscles (gluteus maximus, medius and minimus), covered by deep fascia and a thick layer of subcutaneous fat, form the bulk of the buttock and account for its surface contour. The gluteal fold, a prominent surface feature, lies at the junction of the buttock and thigh.


Gluteus maximus
This very large trapezoidal muscle is the most superficial in the buttock. Its fibres slope downwards and laterally (Fig. 6.28) and its lower edge passes obliquely across the gluteal fold. Some of the sensory nerves to the skin of the buttock penetrate the medial part of the muscle, while others emerge around its upper and lower borders. Proximally, the muscle has an extensive attachment: to the ilium behind the posterior gluteal line, to the lower part of the sacrum, to the coccyx, to the sacrotuberous ligament and to the thoracolumbar (lumbar) and gluteal fasciae. A synovial bursa is usually present where it crosses the ischial tuberosity. Distally, some of the deeper fibres are attached to the gluteal tuberosity of the femur (Fig. 6.29), but most of the muscle is attached through the iliotibial tract (Fig. 6.30) to the anterior surface of the lateral tibial condyle. The nerve supply is from the inferior gluteal nerve (L5, S1 & S2).
Pterygopalatine Fossa Anatomy

Pterygopalatine Fossa Anatomy


Pterygopalatine Fossa Anatomy
The pterygopalatine fossa lies between the pterygoid process of the sphenoid bone posteriorly, the palatine bone medially and the maxilla anteriorly (Fig. 7.43). It is slit-like and opens laterally through the pterygomaxillary fissure into the infratemporal fossa. 
It contains part of the maxillary (V2) division of the trigeminal nerve, the pterygopalatine ganglion and its branches and the termination of the maxillary artery, together with accompanying veins and lymphatics. The pterygopalatine fossa communicates with the middle cranial fossa through the foramen rotundum, with the foramen lacerum through the pterygoid canal, with the orbit through the inferior orbital fissure, with the walls of the nasal cavity through the sphenopalatine foramen and with the palate via the greater and lesser palatine canals.

Maxillary (V2) division of the trigeminal nerve
The maxillary division (Fig. 7.44) leaves the cranial cavity through the foramen rotun- dum, crosses the pterygopalatine fossa and continues forwards through the inferior orbital fissure into the orbit. It terminates as the infraorbital nerve, which traverses the infraorbital canal to reach the face. The maxillary division has several branches arising in the pterygopalatine fossa and the floor of the orbit. In the pterygopalatine fossa (Fig. 7.45), two branches suspend the pterygopalatine ganglion from the parent nerve. Also arising in the fossa are the posterior superior alveolar nerves (Figs 7.44 & 7.45), which descend in the posterior wall of the maxillary air sinus to reach the upper molar teeth. In the floor of the orbit, the middle and anterior superior alveolar nerves (Fig. 7.44) arise and descend in the lateral and anterior walls of the maxilla. Collectively, the superior alveolar nerves supply the maxilla and its air sinus, the alveolar ridge and all the upper teeth. The zygomatic nerve (Fig. 7.44) also arises in the floor of the orbit and ascends on the lateral wall, dividing into zygomaticotemporal and zygomaticofacial nerves. These branches pierce the zygomatic bone to supply the overlying facial skin. A branch from the zygomaticotemporal nerve conveys postganglionic parasympathetic fibres from the pterygopalatine ganglion to the lacrimal gland. The infraorbital nerve (Fig. 7.44) emerges onto the face through the infraorbital foramen and supplies the skin of the cheek, lower eyelid, upper lip and lateral surface of the external nose.
Nasal Cavities and Paranasal Air Sinuses Anatomy

Nasal Cavities and Paranasal Air Sinuses Anatomy

Nasal cavities
The paired nasal cavities lie centrally within the facial skeleton, medial to the orbits and the maxillary air sinuses (Fig. 7.47). They are separated from the oral cavity by the palate, from the anterior cranial fossa by the cribriform plates and from each other by the midline nasal septum. Anteriorly, the cavities lead into the vestibules, which are surrounded by the cartilaginous external nose and open onto the face at the nostrils. 
Posteriorly, the nasal cavities are limited by the free edge of the nasal septum at the choanae (posterior nasal apertures), which open into the nasopharynx. Each cavity is partially subdivided by three shelf-like projections from the lateral wall, the superior, middle and inferior conchae (turbinates Fig. 7.48). The parts of the nasal cavity beneath each of these are called correspondingly the superior, middle and inferior meatuses, while above the superior concha is the sphenoeth-moidal recess. Into this recess and the meatuses drain the paranasal air sinuses and the nasolacrimal duct. Respiratory epithelium lines the cavity and paranasal air sinuses while the vestibule has a stratified squamous epithelium bearing nasal vibrissae (hairs).
Coronal section showing the orbits and nasal cavities. Posterior aspect.

Fig. 7.47 Coronal section showing the orbits and nasal cavities. Posterior aspect. (Compare Figs 7.84 & 7.92.)

Bony walls
The medial wall is the nasal septum (Fig. 7.49), common to both cavities and formed superiorly by the perpendicular plate of the ethmoid. This plate continues upwards as the crista galli, which projects into the anterior cranial fossa. The bony septum is completed posteroinferiorly by the vomer. Anteriorly, the septum is composed of hyaline cartilage which extends into the external nose.
Palate Anatomy

Palate Anatomy


Palate Anatomy
The palate consists of hard and soft parts covered by mucous membrane (Fig. 7.55). The hard palate separates the oral and nasal cavities while posteriorly the soft palate separates the nasopharynx from the oropharynx.

Hard palate
The bones that comprise the hard palate are the palatine processes of the maxillae anteriorly and the horizontal plates of the palatine bones posteriorly (Fig. 7.82). The hard palate is bounded in front and laterally by the superior alveolar ridge. The soft palate is attached to the free posterior border of the hard palate. Sensory fibres reach the palate in branches of the maxillary (V2) division of the trigeminal nerve. The nasopalatine nerve emerges from the incisive foramen and supplies the anterior part of the hard palate. The greater palatine nerve gains the hard palate via the greater palatine foramen and innervates its posterior portion.

Monday, May 3, 2021

Vertebrae and Joints Anatomy

Vertebrae and Joints Anatomy


Vertebrae and Joints Anatomy
Cervical vertebrae
The seven cervical vertebrae are relatively small and enclose a wide vertebral canal with adequate space for the cervical part of the spinal cord. Each transverse process is perforated by a foramen transversarium transmitting the vertebral vessels. The spinous processes all give attachment to a strong midline elastic ligament, the ligamentum nuchae.
Four of the cervical vertebrae (numbers 3–6) have a typical appearance whereas the first, second and seventh are modified. The typical vertebrae (Fig. 8.11) possess short bifid spines and their transverse processes have anterior and posterior tubercles. Often the upper and lower surfaces of the vertebral bodies are not flat but curve upwards at their lateral edges. The facets on the superior articular processes face obliquely backwards and upwards and therefore rotation and lateral flexion always occur together.

The first cervical vertebra, the atlas (Fig. 8.12), has anterior and posterior arches, relatively large transverse processes and two lateral masses. The atlas has no body and its spinous process is represented by a tubercle. On the superior surface of each lateral mass is a concave facet, which articulates with the convex occipital condyle of the skull. The atlantooccipital joints permit flexion and extension (nodding movements).
Muscles Anatomy

Muscles Anatomy


Muscles Anatomy
The muscles of the erector spinae group are covered in the lumbar region by the thoracolumbar fascia, in the lumbar and thoracic regions by the serratus posterior muscles and in the neck by the splenius muscles.
In the lumbar region, the thoracolumbar fascia is trilaminar and encloses erector spinae posteriorly and quadratus lumborum anteriorly (Fig. 8.28). At the lateral margins of both muscles, the laminae of the fascia fuse and give attachment to the transversus abdominis (Fig. 8.28).
Serratus posterior superior and inferior (Figs 8.29 & 8.30) are weak respiratory muscles, which connect lower cervical and upper thoracic spines with upper ribs, and lower thoracic and upper lumbar spines with lower ribs, respectively. They are supplied by branches of anterior rami of thoracic spinal nerves (intercostal nerves).


Splenius muscles
Splenius (Fig. 8.31) attaches medially to the lower part of the ligamentum nuchae and to the upper thoracic spinous processes. The superior part, splenius capitis, attaches laterally to the mastoid process and superior nuchal line. The inferior part, splenius cervicis, attaches laterally to the transverse processes of the upper cervical vertebrae.
Spinal Cord Anatomy

Spinal Cord Anatomy


Spinal Cord Anatomy
Surface features
At the level of the upper border of the atlas, the spinal cord is directly continuous with the medulla oblongata. Inferiorly, the cord usually extends as far as the first lumbar intervertebral disc, where it terminates as the conus medullaris. In transverse section, the spinal cord is oval, with its smaller diameter anteroposteriorly. The cord is especially wide at the cervical and lumbar enlargements due to increased numbers of nerve cell bodies within the spinal cord, which innervate the upper and lower limbs.
On the anterior aspect of the cord lies the anterior median fissure, whereas posteriorly, there is a relatively shallow posterior median sulcus. On each side, a posterolateral sulcus marks the site of attachment of the posterior nerve roots.

The spinal nerves are attached to the spinal cord by anterior and posterior nerve roots

Spinal nerve roots
The spinal nerves are attached to the spinal cord by anterior and posterior nerve roots (Fig. 8.36). The region of the spinal cord to which one pair of anterior and posterior nerve roots attaches is called a spinal segment (Table 8.3).

Monday, April 19, 2021

Palm and Digits Anatomy

Palm and Digits Anatomy


Palm and Digits Anatomy
The hand comprises the wrist (carpus), the palm (metacarpus) and the digits (Figs 3.37 & 3.38). The palm of the hand (Fig. 3.39) contains the palmar aponeurosis, intrinsic muscles, tendons originating from muscles in the anterior compartment of the forearm, and palmar vessels and nerves. The intrinsic muscles comprise the thenar and hypothenar groups, the lumbricals and interossei, and adductor pollicis. The tendons enter the palm through the carpal tunnel (Fig. 3.98) deep to the flexor retinaculum. The skin of the anterior surface of the hand is thick, devoid of hair and contains many sweat glands. It is firmly bound to the underlying deep fascia, producing characteristic creases. Skin over the palmar surface of each distal phalanx is firmly tethered to the periosteum by fibrous septa, which enclose fat-filled spaces. Infection causing increased pressure in the pulp space may result in thrombosis of vessels supplying the distal phalanx causing bone necrosis.


Deep fascia of the palm
The deep fascia of the palm is thickened centrally to form the triangular palmar aponeurosis (Fig. 3.39) and is thinner at each side where it covers the thenar and hypothenar muscles. Proximally, the palmar aponeurosis attaches to the flexor retinaculum and is continuous with the tendon of palmaris longus. Distally, the aponeurosis gives rise to four pairs of digital slips, which cross the metacar- pophalangeal joints and attach to the proximal phalanges of the fingers via the fibrous flexor sheaths. The aponeurosis covers the superficial palmar arch, the median nerve and the tendons of the long flexors of the digits. Thickening and shortening of the aponeurosis in Dupuytren’s contracture produces fixed flexion of the metacarpophalangeal and proximal interphalangeal joints.

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